ISMA 2019

Organization:

J. Angster, Fraunhofer-Institut für Bauphysik, Stuttgart T. Grothe, Hochschule für Musik Detmold, Detmold

25 Years Applied Pipe Organ Research at Fraunhofer IBP in Stuttgart Judit Angster, Péter Rucz, András Miklós [Abstract] Throughout the world, musical instruments are deeply rooted in cultural traditions. They are part of our cultural heritage, and their preservation and further development deserves our utmost attention. For many years, the Fraunhofer Institute for Building Physics IBP has been engaged in the research of European musical instruments, the organ in particular. To preserve its sound, to give support in building instruments as well as to contribute to the further development by integrating modern technologies are the focus of the joint research with other research institutions and a multitude of European organ building enterprises. In 25 years, 9 common European and several other research projects were carried out. Some examples of the topics will be mentioned like development of 1) different kinds of new wind systems, methods and software for the design, 2) design methods, tools and software with applying computer simulations for flue and reed organ pipes 3) innovative swell shutters, 4) design methods and comprehensive tools for matching the instrument on the acoustics of the room. The procedure of research, way of communication with instrument builders, the method of demonstration and dissemination of the research results will be discussed.

Session chair(s):

J. Angster, Fraunhofer-Institut für Bauphysik, Stuttgart T. Grothe, Hochschule für Musik Detmold, Detmold

	Numerical study on the function of the register hole of the Clarinet Kin'Ya Takahashi, Kana Goya, Saya Goya, Genki Tsutsumi, Taizo Kobayashi [Abstract] The function of the register hole of the Clarinet can be basically explained from the common property of two delay systems (J. Phys. Soc. Jpn, Vol.83, 124003 (2014)). Namely, if the strength of a short time delay is sufficiently small but non-negligible, the third harmonic is well sustained over a wide range of the short delay time. This fact indicates that the register hole with a small radius raise the pitch of the first register notes in a wide range more than an octave to the second register notes by a twelfth (19 semitones). However, the reflection function has many delay peaks even when only the register hole is opened. That is, the clarinet should be characterized as a multi-delay system. In this paper, we focus on the effect of a very short time delay, which characterizes the reflection from the discontinuity in the mouthpiece. We numerically found that the function of register hole survives even for such a three delay system including the reflection from the mouthpiece.
	Numerical study on unsteady fluid flow and acoustic field in the clarinet mouthpiece with the compressible LES Toshiaki Koiwaya, Sho Iwagami, Taizo Kobayashi, Kin'Ya Takahashi [Abstract] The sound generation in the clarinet mouthpiece is still an unsolved problem from the view point of aeroacoustic and has been studied theoretically, experimentally and numerically by many authors. Numerical simulations on the unsteady flow in the clarinet mouthpiece using LBM have been reported by several authors. In this paper, we numerically study unsteady fluid flow and acoustic field in the clarinet mouthpiece with compressible LES. We adopt 2D and 3D models and the 3D model has numerical grids more than one hundred and 50 million to reproduce detail behavior of air-jet motion, vortices and acoustic filed. In our models, the reed is fixed and an uniform flow is injected from the reed slit to study the behavior in the attack transient. The 2D and 3D models behave in different ways. For the 2D model, the injected jet is rolled up making long-lived rotors in the mouthpiece, while for the 3D model it is destabilized in a certain distance is broken into a lamp of turbulence. We also study the station that an alternating current is injected from the slit to reproduce the acoustic resonance.
	Computational Aeroacoustic Modeling of Single-Reed Mouthpiece Using Palabos Song Wang, Gary Scavone [Abstract] The sound generation behavior of a single-reed instrument can be determined from its aeroacoustic characteristics. Computational aeroacoustics (CAA) modeling offers a mean to analyze the aeroacoustics behavior of such a system. The lattice Boltzmann method (LBM) models fluid on a mesoscopic level and has certain advantages over traditional Navier-Stokes approaches in solving CAA problems. In this study, we present results from an aeroacoustic analysis of a 2D single-reed mouthpiece system using an open- source, parallelized lattice Boltzmann solver called Palabos. A variety of functionalities and components are investigated, including the parallelization, the grid refinement, the moving boundary, and the non-reflecting boundary condition, which demonstrates the versatility of Palabos. Different mouthpiece geometries are tested with both static and moving reeds. The nonlinear characteristics of the mouthpiece-reed system derived from this study are then compared with the theoretical quasi-static flow model.

Session chair(s):

J. Angster, Fraunhofer-Institut für Bauphysik, Stuttgart T. Grothe, Hochschule für Musik Detmold, Detmold

	How do flute players adapt their control parameters to modifications of the flute bore? Benoit Fabre, Patricio De La Cuadra, Augustin Ernoult [Abstract] Skilled players can adapt their control parameters according to the response of the instrument they are playing. In the case of the flute, lips and face position relative to the mouthpiece are the main adjustments used for a fine control of the pitch, while the detailed geometry of the flute bore determines the intonation profile of the instrument along its tessiture. In this paper we introduce and explain the idea of a negative bore in which we control subtle modifications of the intonation profile of the flute. Skilled players are then invited to play on different profiles of the same instrument while the geometrical and hydrodynamical control parameters are monitored. The paper will discuss the adjustments observed in the control strategy of the players, as function of the intonation profiles measured.
	Experimental study on the temporal fluctuation of harmonics in flute sounds Keita Arimoto [Abstract] There are some studies on the temporal fluctuation of harmonics in flute sounds. However, it is still unclear whether it is due to the fluctuation coming from human player or the nature of the sounding mechanism. In this study, an experiment was conducted to investigate temporal fluctuations purely due to the sounding mechanism of the flute. For this purpose, an artificial blowing system was built in order to yield flute sounds by a constant air flow as well as by adjusting the angle, offset, length and velocity of the jet. The temporal fluctuation for a harmonic component was computed by a standard deviation for a series of instantaneous harmonic amplitudes obtained from short-time audio analysis. The result shows that the temporal fluctuation increases as the average harmonic amplitude decreases, and vice versa. The effect of the temporal fluctuation on perceptual impression was finally confirmed by a synthesis experiment where flute sounds were re-synthesized with controlling the amount of the temporal fluctuation.
	Experimental Investigation for Effects of Jet Angle on the Harmonic Structure in the Flute Onogi Kimie, Ai Natsubori, Hiroshi Yokoyama, Akiyoshi Iida, Keita Arimoto [Abstract] To clarify the effects of jet angle on the radiated sound from the flute, the radiated sound and jet fluctuations were experimentally investigated. An artificial blowing device with an artificial oral cavity was used to change the jet angle and the geometric jet offset (the relative height of the vertical line of the cavity exit center from the edge) independently. The actual jet offset (the relative height of the jet fluctuation center from the edge) was estimated based on the velocity profile measured by a hot-wire anemometer. Under the condition that the geometric jet offset is zero, the actual jet offset changed with the jet angle. Also, the sound of the second/third mode radiated more/less intensely with larger actual jet offset, while the radiated sound of the first mode remained almost the same level. These results indicate that the variation of the jet angle affects the actual jet offset, which affects the harmonic structure.

Session chair(s):

J. Angster, Fraunhofer-Institut für Bauphysik, Stuttgart T. Grothe, Hochschule für Musik Detmold, Detmold

	Finite element simulation of radiation impedances with applications for musical instrument design Péter Rucz, Judit Angster, András Miklós [Abstract] Creating a musical instrument often involves designing acoustical resonators. The natural frequency and the quality factor of the resonator are affected by the radiation impedance to a significant extent. Therefore attaining as much a priori knowledge as possible on the radiation characteristics is desirable. On the other hand, for the sake of efficiency, radiation characteristics are most often reduced to a sole frequency dependent radiation impedance function. A finite element approach for the calculation of self and mutual radiation impedances was introduced recently [Rucz, JASA 143(4) 2449-2459], which is suitable for these purposes. In this contribution, the methodology is applied and extended with different applications in musical instrument design. In particular, the radiation from the mouth regions of organ pipes and recorders are examined. The geometrical parameters having the most significant effect on the radiation characteristics are analyzed and the results are compared to previously published data. As another example, finite element simulations of Helmholtz resonators of a mallet percussion instrument are introduced. In this case, the length correction effect of the sound bars partially covering the opening of the resonators is studied. Finally, the effect of viscous losses on the quality of the natural resonance is investigated.
	Numerical study of Synchronization Phenomena of an Air-Jet Instrument using Finite-Difference Lattice Boltzmann Method Ryoya Tabata, Taizo Kobayashi, Kin'Ya Takahashi [Abstract] Coupled Van der Pol oscillators are often used for the studying of synchronization mechanism among flue organ pipes. However, recent studies have suggested that the effect of near-field interaction between the air-jet motion and the acoustic field plays an important role in the mechanism of synchronization. In this study, we focus on the synchronization between an air-jet instrument and external sound source. We numerically explore the synchronization mechanism using a finite-difference lattice Boltzmann method (FDLBM) as a direct aeroacoustic simulation scheme in two dimensions. We succeed in reproducing the frequency-locking phenomenon between the monopole sound source and air-jet instrument in the stationary state. Numerical simulations are conducted on a GPU cluster to explore the large parameter space. Transient behavior towards the frequency-locking phenomenon was observed, and the results demonstrate that the external sound source strongly affects the air-jet oscillation and the phase relationship of the sound pressure inside the resonator.
	From the bifurcation diagrams to the ease of playing of reed musical instruments. A theoretical illustration of the Bouasse-Benade prescription? Joël Gilbert, Sylvain Maugeais, Christophe Vergez [Abstract] Reed musical instruments can be described in terms of conceptually separate linear and nonlinear mechanisms: a localized nonlinear element (the valve effect due to the reed) excites a linear, passive acoustical multimode element (the musical instrument usually represented in the frequency domain by its input impedance). The linear element in turn influences the operation of the nonlinear element. The reed musical instruments are self-sustained oscillators. They generate an oscillating acoustical pressure (the note played) from a static overpressure in the player’s mouth (the blowing pressure). A reed instrument having N acoustical modes can be described as a 2N dimensional autonomous nonlinear dynamical system. A reed-like instrument having two quasi-harmonic resonances, represented by a 4 dimensional dynamical system, is studied using the continuation and bifurcation software AUTO. Bifurcation diagrams are explored with respect to the blowing pressure, with focus on amplitude and frequency evolutions along the different solution branches. Some of the results are interpreted in terms of the ease of playing of the reed instrument. They can be interpreted as a theoretical illustration of the Bouasse-Benade prescription.

Session chair(s):

J. Angster, Fraunhofer-Institut für Bauphysik, Stuttgart T. Grothe, Hochschule für Musik Detmold, Detmold

	The Khaen as a Miniature Pipe Organ James Cottingham [Abstract] The khaen is a Southeast Asian mouth organ consisting of a number of free-reed pipes (commonly sixteen) mounted in a wooden wind chamber. From one point of view, it is possible to think of this instrument as an extremely small pipe organ: one with one rank of sixteen free-reed pipes. There have been a number of studies of the khaen in recent decades, often focusing on the coupling between a single reed and the pipe in which it is mounted. Yet music for the khaen, both traditional music and new music by current composers and players, almost always involves multiple notes sounding simultaneously. This paper summarizes some investigations involving the instrument as a whole, sometimes observing similarities and differences between the khaen and the pipe organ. A significant difference is the wind supply, which in the khaen is continually reversing direction. This certainly affects the musical playing style of the instrument, but may have other acoustical complications. Another area recently explored experimentally involves possible musical consequences of mode locking between pipes.
	The air jet development in organ pipe tone attack caused by voicing adjustments Zdenek Otcenasek, Pavel Dlask, Jan Otcenasek [Abstract] The contribution presents the results of a research on differences in development of air jet fluxes in labium of a rectangular organ flue pipe caused by different voicing adjustments. Air jets of tone starting transients were observed by laser PIV (particle image velocimetry) on a single transparent pipe with varied combinations of the upper lip height (cut-up), the flue slit area (breadth) and the windchest air pressure. Visualizations of the air jet velocity vectors will be linked to a development of sound pressure and descriptions of sound quality from a listening test.
	Distortion of acoustic shockwaves by U-shaped tube portions Sebastien Ollivier, Thomas Lechat, Didier Dragna, Arnaud Gluck [Abstract] Nonlinear propagation models for wave propagation in the resonator of brass instruments are generally based on a one-dimensional description. This description is made under the hypothesis that sound wave propagation does not depend on bends, and is the same for straight or curved resonators. However, brass instruments resonators are not straight, and the effects of bends have to be considered. Modal approaches have shown that the pressure field has no symmetry in curved ducts, both in linear and weakly nonlinear propagation. The present study addresses the question of the behavior of shockwaves in U-shaped tubes with geometries close to some parts of brass instruments resonators, For this purpose, both experiments and numerical simulations in time domain have been performed. The experiments are based on optical measurements requiring a square section of the U-shaped portion of the duct. The corresponding numerical simulations have been performed by solving the 2D Euler equations in curvilinear coordinates using a finite-difference time-domain approach. Results reveal the dynamics of shock propagation, the nonlinear interaction of shocks, and the distortion of the waveform.

	Kora-Som: an interface that converts a player's beating heart into a real-time metronome Leonardo Fuks, Gabriel Moura, Frederico Jandre [Abstract] The heart beat is a central timing reference in life and in music. Several composers and players along history have mentioned the heart rate as a measure for the musical pulse. On the other hand, it is known that listening and playing music affects the heart beat frequency. besides other physiological signals. The purpose of this project consists of building a device that detects, measures and replicates a subject’s heart beat and makes it available for musical research and performance. The Kora-Som system employs a commercial heart rate sensor, widely used in sports. The data from this meter are received and decoded by a remote sensor, connected to an arduino and a portable computer. A piece of software generates and plays sounds from wavetables, melodic sequences, midi files and other formats and protocols. A player may litterally play with his/her own heart, what opens a large range of composing and improvising fields. A whole musical group is able to play to/with a certain listener, such as a health patient, in a very touching and stimulating situation. All timing and performing data is recorded and made available for eventual processing and evaluation.
	A Liquid Sloshing Vibrato Mechanism for the Symbaline; an Active Wine Glass Instrument Lior Arbel, Yoav Y. Schechner, Noam Amir [Abstract] The Symbaline is an active instrument consisting of water tuned wine glasses excited by electromagnets. Its timbre is characterized by steady overtones and a smooth attack-decay envelope. In this presentation we describe an electromechanical system for adding vibrato to the Symbaline’s sound. The system consists of a pendulum with a magnetic bob, submerged inside the liquid in the wine glass. Infra-sound signals are sent to an electromagnet external to the glass, generating a magnetic field which puts the pendulum into oscillation. As a result of the pendulum’s movement the liquid in the glass sloshes and the water level fluctuates in a periodic manner. Audio frequency signals are sent to the same electromagnet, in parallel, inducing vibrations in the wine glass itself, by exciting a small magnet on the glass’s surface. While the glass is radiating sound, its resonance frequencies are altered by the changing water levels, resulting in frequency and intensity modulation.
	A real-time feedback system for vocal tract tuning Marie Jeanneteau, Noel Hanna, John Smith, Joe Wolfe [Abstract] The first resonance of the vocal tract (an impedance minimum when measured at the lips) is tuned by some singers: all of the sopranos we have studied, whether trained or not, tune R1 to fo over the range roughly C5 to C6; altos and tenors sometimes tune it to one of the lower harmonics in their upper range. Sopranos who practise the range substantially above about C6 tune the second resonance R2 to fo. The first purely acoustic impedance maximum is tuned by saxophonists and clarinettists under some conditions. This paper introduces a public version of software that can be used in a system to teach vocal tract tuning using a nearly real-time display and a graphical user interface. Our first use of it was to teach R2:fo tuning to sopranos. In a one-hour session, some subjects learned tuning over a limited range, but only with the interface running, while others did not learn tuning. One of the authors (MJ) spent several hours with the system and learned to extend her range of R2 variation and could use R2:fo tuning over from F5 to E6, with and without the visual feedback. Training resonance tuning on saxophone is also proposed.
	Experimental setup for real-time control of a single-reed woodwind instrument model Alex Hofmann, Sebastian Schmutzhard, Vasileios Chatziioannou [Abstract] This paper demonstrates an experimental setup for music acoustic experiments and contemporary music performance following a hybrid physical modelling approach. In this setup, a clarinet mouthpiece with a sensor-equipped reed is coupled to a virtual tube. A C++ implementation of a tube model is presented in the form of a Csound opcode which runs on the ultra low-latency audio platform Bela. The coupling is realised with an actuator that acts on the sensor-reed. The actuator is driven by the virtual pressure at the closed end of the tube model, whereas the sensor-reed signal is fed back to the model as volume flow. The experimenter can modify the parameters for length, radius, conicity, end-reflection and air density of the tube model, and is also given control over the coupling between reed and actuator in real time. This setup allows to explore acoustic phenomena that are usually either enclosed (reed-resonator coupling) or static (e.g. resonator shape) in conventional acoustic instruments and may also be useful for music acoustics training.

	Physical principle of pitch bent by cross-fingering Seiji Adachi [Abstract] Cross-fingering is a technique of playing woodwind instruments in which one or more tone holes are closed below the first open hole. It usually yields a pitch lower than that played with normal fingering. However, pitch is raised in exceptional cases. Pitch flattening has been traditionally understood using the lattice tone hole theory. On the other hand, pitch sharpening has been scarcely explained except for pointing out the possibility for the open hole to act as a register hole. This talk proposes understanding these pitch bending phenomena in a unified manner with a model of two coupled mechanical oscillators. Bores above and below the open hole interact with each other by sharing the air in the open hole oscillating as a lumped mass. This mechanism is known in physics as avoided crossing or frequency repulsion. With an extended model having three degrees of freedom, pitch bending of the recorder played with cross-fingering in the second register can also be explained.
	A parametric study of finger motions when playing the clavichord: towards characterization of expressive control Jean-Théo Jiolat, Jean-Loïc Le Carrou, Christophe D'Alessandro [Abstract] The clavichord is considered to be the most demanding keyboard instrument in terms of finger control. This is because of its direct mechanisms: the key works as a lever. When the finger presses the key, the tangent (metal rod) on the key’s extremity goes up and strike the string. And as long as the finger remains pressed on the key, the tangent remains in contact with the string, leading to string’s tone variation. The loudness of the sound is proportional to the velocity of the key’s displacement. Then there is a duality between loudness and pitch accuracy. This is the paradox of the clavichord. The objective of the study is to analyze experimentally the sounding consequences of the instrument with respect to the gestural strategies of the finger. To proceed, we use a robotic finger that can simulate different trajectories, either ideal trajectories (e.g. vertical or sliding motions) or actual trajectories performed by clavichord players. Players’ trajectories are extracted by image processing of films made by a high-speed camera. Vibratory and acoustical measurements are performed, upon which relevant indicators are used to compare different configurations. The finger performing a circular motion reaches a good compromise between tone and loudness.
	Factors affecting transients in rapid articulation on a bass crumhorn Alan Woolley, Murray Campbell, Simon Carlyle [Abstract] The generation of a pitched note on a reed instrument involves a nonlinear acoustic coupling between the mechanical reed and the air column of the instrument. Once a stable regime of oscillation has been achieved the reed vibrates at the playing frequency, which is much lower than the reed natural frequency. On windcapped instruments like the crumhorn a change in the playing frequency is initiated by opening or closing toneholes. This modifies the acoustic resonances frequencies of the air column, and the pressure feedback to the reed causes its vibration frequency to change. Factors affecting the transients during rapid pitch changes on a bass crumhorn have been investigated using high speed video recording of reed motion, laser-based position tracking of the reed tip vibration, and measurements of pressure upstream and downstream of the reed.

Music Practice Rooms: Ambitions, Limitations and Practical Acoustic Design Claudiu Pop, Riduan Osman, Julia Knight [Abstract] The acoustic design of music practice rooms is a well-researched and investigated topic. This study reviews critically the acoustic parameters generally accepted as desirable for these rooms and provides insight from a practitioners perspective. A series of music practice rooms are discussed and a holistic discussion is provided on the design challenges and successes as part of a multidisciplinary team of acousticians, architects, building services and structural engineers.

Acoustical evaluation of differences in Sanshin’s tone depending on shapes of SAO Kojiro Nishimiya, Mao Tokuda, Yuki Yokota, Hideo Cho [Abstract] Sanshin is an OKINAWA’s traditional musical string instrument. Generally, the sound board is one of the main factors on the string instrument’s tone from the acoustical points of view. Nevertheless, about Sanshin, the player and artisan have thought that Sao (Neck) has been the most important. Sanshin has many types of Sao and there have many arguments of the relationship between ”Sao” and ”Tone”. However, the sound mechanism is still not clarified. Therefore, the purpose of this research is to elucidate the sound mechanism of Sanshin which include the influence of Sao. We measured the Sanshin’s tone using different types of SAO with the same body, string, and bridge. As a result, we found the several differences in the tones. Especially the differences were confirmed in the frequency distributions and the attenuation rates. For the understanding of these behaviors, we focused about the change of the thickness and length of SAO, and the mass damping of the head of SAO. By the cutting works of one wood-Sanshin, we found that the thickness and length of SAO influence the frequency distributions and the mass damping influences the attenuation rate.

Session chair(s):

M. Kob, Detmold University of Music, Detmold

	External sound field simulations and measurements of woodwind resonators Erik Alan Petersen, Romane Rosser [Abstract] The input impedance is a useful quantity to characterize the acoustic response of woodwind instruments and is efficiently simulated using the Transfer Matrix Method (TMM). However, the TMM does not calculate intermediate variables that are convenient for simulating the external sound field. Recent work by Lefebvre et al proposes the Transfer Matrix Method with external Interactions (TMMI) which accounts for the mutual radiation impedance of toneholes radiating into the same space and uses the acoustic flow through each aperture as the reference variable. Treating the flow through each tonehole as a source in a linear array, it is possible to calculate the external sound field such as the waveforms at a given receiver location and directivity patterns. Additionally, the efficiency of a resonator can be calculated as the ratio of the power at the input of the resonator and the sum of the power radiating from each aperture. This is a useful step towards understanding the competition between the energy that is retained within a resonator and facilitates the auto-oscillation of the reed, and that which radiates from the resonator. This topic is explored through simulation and measurements using simplified cylindrical resonators.
	Impact of free field inhomogenity on directivity measurements due to the measurement set-up Malte Kob, Alexis Baskind [Abstract] Measurements in anechoic conditions are affected by the measurement set-up itself. The presence of grids, stands, turntables and the human body introduces reflections, diffraction, absorption and more changes to the ideally free field conditions. The impact of such equipment on directivity measurements is often neglected, and artefacts are are easily mis-interpreted as features of the source directivity. In an anechoic chamber several setups are compared with respect to changes in the measured directivity of a simplified musical instrument. The differences of the 1/r amplitude decay as well as the resulting directivities are presented and discussed.
	Piano strings with reduced inharmonicity Jean-Pierre Dalmont, Sylvain Maugeais [Abstract] The inharmonicity of the lower strings of straight pianos is still rather large especially for the first octave. Consequently, the timber of these strings can be sometimes awful and chords on the first octave highly dissonant. The idea of the present study is to show how this defect can be rectified by using an inhomogeneous winding on the whole string in order to minimize inharmonicity. The problem is solved by using an optimization procedure considering a non uniform linear density. Result show that the inharmonicity can be highly reduced. First results on a real string will be presented and discussed.

Session chair(s):

M. Kob, Detmold University of Music, Detmold

	ODESSA - Orchestral Distribution Effects in Sound, Space and Acoustics: an interdisciplinary symphonic recording for the study of orchestral sound blending Martha De Francisco, Malte Kob, Jean-François Rivest, Caroline Traube [Abstract] ODESSA is a collaborative project between the Université de Montréal, McGill University and Detmold University of Music aiming to study orchestral blending effects, examining how instrumental sounds are sculpted by the conductor, the musicians and the hall acoustics and how the sound changes when heard and recorded from different perspectives. This project is realized in context of the ACTOR (Analysis, Creation, and Teaching of Orchestration) partnership, which involves a diverse international team of composers, music theorists, musicologists, computer and signal processing scientists, psychologists, acousticians, sound recordists and conductors. ACTOR’s main goals are to develop a perceptually based theory of orchestration and to create new tools for music analysis, composition, teaching and mediation. Under the combined leadership of four researchers, the ODESSA project consists of a complex multitrack recording of the Orchestre de l’Université de Montréal performing excerpts from Tchaikovsky’s Sixth Symphony, ”Pathétique”. More than 50 microphones are used in a combination of close microphone pick-up and ambient recording. Concurrently, the acoustical balance of the instruments is examined employing techniques such as 3D intensity probes and an acoustic camera. Excerpts of the recording of varying instrumental combinations are used as listening test stimuli with the purpose of investigating timbral blending effects.
	Investigation of the Blending of Sound in a String Ensemble Stefanos Ioannou, Malte Kob [Abstract] Ensemble sound is a topic where, to date, only little research has been conducted. A fundamental question that still needs to be answered is how many instruments of the same section are required for a group to blend together as an ensemble. As part of the ACTOR project, a violin phrase from Tchaikowsky’s 6th Symphony has been recorded with one, two, three, four, six and ten violins using piezo microphones, spot microphones, a decca tree, room microphones, and a dummy head. Based upon these recordings a listening test was designed, in which participants had to (1) guess the number of violins and (2) state whether the recording sounds like an ensemble. Results reveal that a majority of listeners perceive an ensemble sound for a relatively low number of instruments whereas the number guess task fails for lagern numbers. The microphone location relative to the instruments is of major importance.
	Sounds Like Melted Chocolate: How Musicians Conceptualize Violin Sound Richness Charalampos Saitis, Claudia Fritz, Gary Scavone [Abstract] Results from a previous study on the perceptual evaluation of violins that involved playing-based semantic ratings showed that preference for a violin was strongly associated with its perceived sound richness. However, both preference and richness ratings varied widely between individual violinists, likely because musicians conceptualize the same attribute in different ways. To better understand how richness is conceptualized by violinists and how it contributes to the perceived quality of a violin, we analyzed free verbal descriptions collected during a carefully controlled playing task (involving 16 violinists) and in an online survey where no sound examples or other contextual information was present (involving 34 violinists). The analysis was based on a psycholinguistic method, whereby semantic categories are inferred from the verbal data itself through syntactic context and linguistic markers. The main sensory property related to violin sound richness was expressed through words such as full, round, and dense versus thin, weak, and small, referring to the perceived number of partials present in the sound. Another sensory property was expressed through words such as warm, velvety, and smooth versus strident, harsh, and tinny, alluding to spectral energy distribution cues. Haptic cues were also implicated in the conceptualization of violin sound richness.

Session chair(s):

J. Smith, Center for Computer Research in Music and Acoustics (CCRMA), Stanford University, Stanford, Ca

	Influence of tonewood parameters on the perceived sound quality of a steel-string acoustic guitar Sebastian Merchel, David Olson, M. Ercan Altinsoy [Abstract] Wood is one of the preferred materials for building stringed music instruments. Because wood is a naturally grown resource, there is large variability regarding material properties. Therefore, luthiers select their tonewoods carefully. In this project, listening tests were performed to investigate whether the objective testing of physical parameters of the tonewood help to make an appreciable impact on the sonic quality of the resulting instrument. Nine steel string guitars of the same model were produced by the Taylor Guitar Company, with strict control of all production parameters. The guitars varied only in two parameters: the density and the modulus of elasticity of the soundboard and bracewood, both made of Sitka spruce. The variability was representative of the range of the spruce wood currently produced by Pacific Rim Tonewoods, a supplier of tonewood to the acoustic guitar market. A short music sequence was used for pairwise preference evaluation in a double-blind listening test. The results suggest that, for this particular model (the Taylor 814ce Grand Auditorium), low density and stiffness of the guitar top have a positive impact on the overall preference. More generally, the results underscore the importance of integrating the design with physical characteristics of the component wood.
	The Bilbao project : How makers match backs and tops to produce particular sorts of violins Claudia Fritz, George Stoppani, Unai Igartua, Roberto Jardón Rico, Ander Arroitajauregi, Luis Artola [Abstract] The Bilbao project aims at answering this question by relating intrinsic characteristics of the materials (wood density and stiffness) and some geometric characteristics of the violin’s constituent parts (thicknesses of the plates) with the tonal qualities of the complete violins. To this end, six instruments were carefully built : three instruments with normal backs, each paired with a pliant (thin), normal, or resistant (thick) top ; similarly, three with normal tops, each paired with a pliant, normal, or resistant back. The two examples of normal top paired with normal back serve as a control. Wood for tops and backs were closely matched in density and sound speeds - all tops and backs from the same trees. Greater control was achieved by having all plates and scrolls cut by CNC routers. The outside surface was not changed during the experiment, as the graduation was performed entirely on the inside surface. In addition, structural measurements were taken at many steps during the building process and the instruments were then assessed during playing and listening tests. These six instruments constitute therefore an unprecedented set of carefully controlled and documented violins, and offer an incredible opportunity for conducting various analyses and correlations.
	Metamaterials in Musical Instruments Rolf Bader, Jost Fischer, Malte Münster, Patrick Kontopidis [Abstract] Acoustic metamaterials are complex geometries leading to acoustic behavior not found in natural material, like negative stiffness or refraction, cloaking or spectral bandgaps. Indeed musical instruments are complex structures and some may already qualify as metamaterials. Still altering the instrument geometries and adding metamaterial behavior can increase the instruments sound variability and articulatory possibilities or lead to sounds not expected from mechanical instruments at all. The paper presents such examples. When modifying a frame drum by adding additional point masses forming a ring, the frame drum shows cloaking behavior when struck in the middle of the ring, where frequencies within a certain frequency band cannot leave the ring. This leads to a bandgap in the spectrum in the mid frequency range. Still when striking the drum outside the ring a normal drum sound is achieved. Therefore a drummer can produce sounds not known from drums before while with the same instrument can also play regular sounds. Other examples are modified guitar top plates with added point masses or waveguide structures.

Clarinet tonguing: the mechanism for transient production André Almeida, Weicong Li, Lauren Inwood, John Smith, Joe Wolfe [Abstract] Players coordinate tongue release and variation in blowing pressure to produce a range of desired initial transients, e.g. for accents and sforzando, players use higher pressures at release to give higher rise rates in the exponential phase. The mechanisms were studied with high-speed video and acoustic measurements on human and artificial players of clarinets and simpler models. The initial mechanical energy of the reed due to deformation and release by the tongue is quickly lost in damping by the lip. The varying aperture as the reed moves towards equilibrium produces proportional variations in flow and pressure via a mechanism resembling the water hammer in hydraulics. Superposition of this signal with returning reflections from the bore give complicated wave shapes with variable harmonic content. When the reed gain more than compensates for losses, a nearly exponential phase follows until the last few oscillations before saturation. Maximal exponential decay rates (in tongue-stopped staccato notes) agree with losses measured in the bore impedance spectrum. Including estimates of the negative reed resistance explains semi- quantitatively the rise rates for initial transients. Different rates for higher harmonics contribute to different wave shapes and spectral envelopes, which are illustrated and modelled here.

Perception of violin soundpost height differences Lei Fu, Claudia Fritz, Gary Scavone [Abstract] This experiment explores how changes in soundpost height affect the perceptual qualities of the violin and whether there is a threshold of change below which players do not perceive differences. A violin installed with a height-adjustable carbon soundpost was employed. The experiment was designed as a sequence of playing tests. An experimenter was present to change the soundpost height. Thirteen professional violinists and six luthiers participated. The experiment involved two phases. During the first phase, subjects played and described their feelings about the violin with different soundpost settings in order to find their optimal soundpost height. During the second phase, the experimenter randomly increased, decreased or did not change the soundpost height in ten trials within a range of approximately ±0.1 mm around their optimal height. Subjects were asked to play the violin for each trial and compare it with the previous setting, to decide whether they were the same or different. Initial results indicate that each subject’s optimal soundpost height varies within an interquartile range of 0.3mm and the smallest height variation that could be recognized above chance level is about 0.04mm.

Session chair(s):

R. Bader, Institute of Systematic Musicology, Hamburg J. Gilbert, Laboratoire d'Acoustique de l'Université du Mans - UMR 6613 CNRS, Le Mans Cedex 9

	Acoustics of Bifacial Indian Musical Drums with Composite Membranes Anurag Gupta, Vishal Sharma, Shakti Singh Gupta [Abstract] We are interested in a certain class of bifacial Indian drums, such as dholak, pakhawaj, and mrdangam, which consist of composite circular membranes stretched over an enclosed air cavity on both sides of an axisymmetric wooden shell. There is a large variety of such drums in Indian music which differ from each other in shapes and sizes of the shell and in the nature of the composite membranes. These drums produce sounds which have a definite pitch and hence can be qualified as musical in nature. Whereas, the effect of the composite nature of the membrane is well studied in the context of the monofacial Indian drum tabla, the acoustical implications of the coupling between two composite membranes (of different material and geometric properties) through an air cavity remains unexplored. The purpose of this work is to study this acoustical problem using a finite element method based numerical methodology. The aim is to solve the coupled structural acoustic boundary-value-problem for the enclosed air pressure and the membrane vibration. In our detailed investigation, we will study the effect of cavity size and shape, as well as the properties of the composite membranes, on the acoustics of the bifacial drums.
	Acoustic measurement of Marimba, Xylophone and Xylorimba Masanobu Miura, Nozomiko Yasui [Abstract] A set of wooden-keyboard percussion instruments, namely xylophone, marimba and xylorimba are acoustically compared. Since the size of xylophone and marimba has not had a standard size, their size and tone have a variety among them. More concretely, an American company Deagan produced the xylorimba between 1920- 1930, which was played by a xylophone player Yoichi Hiraoka, and then conveyed to Japan. The timber of xylophone is felt as to have the features of both marimba and xylophone. The acoustic feature is, however, not measured until now. A professional marimba player cooperated in our experiment. She is asked to play a single note C4 with a consistent hard mallet. The power spectrum of recorded acoustic signal is evaluated in terms of salient peaks on the recorded sound. Although the salient peaks on marimba and xylophone are almost well-known shapse, the one on the xylorimba has a distinct feature, which has 1) consonant peaks to F0, such as 2oct and 3oct+perfect 5th and 2) dissonant peaks to F0, such as 3oct major 2 degree (detuned to +1 and +22 cents). Therefore, the xylorimba is acoustically confirmed as to have both xylophone and marimba’s features.
	Relating tone height and perceived pleasantness in the didgeridoo and bass trombone Noam Amir, Yasmin Bachar-Yakobi [Abstract] The motivation for this study came from the informal observation that didgeridoo tones seem to sound pleasant only over a span of less than an octave, while brass wind instruments of various types are found to be useful and pleasant over a much wider range. We therefore set out to explore the relationship between tone height and its perceived pleasantness and compare these evaluations both on a set of didgeridoos and on a bass trombone playing identical notes over a range slightly larger than one octave. Twenty listeners compared recordings of short tones from G1 to B2, played both on a bass trombone and a set of tubular didgeridoos, by proficient players. The listeners were asked to rate each note on a sliding scale from ”very pleasant” to ”very unpleasant”. Results showed that overall, the didgeridoo tones were found to be significantly more pleasant than the trombone tones. Surpisingly, the trombone tones were found to be more pleasant as tone height increased, while no correlation between tone height and pleasantness was found for the didgeridoo.

	Experimental and Simulative Examination of the String-Soundboard Coupling in an Acoustic Guitar Alexander Brauchler, Pascal Ziegler, Sabina Benatti Camargo, Peter Eberhard [Abstract] The acoustic guitar is a popular string instrument in which the sound results from a coupled mechanical process. The oscillation of the plucked strings is transferred through the bridge to the body which acts as an amplifier to radiate the sound of the guitar. In this contribution, the vibration of a guitar and the coupling between the strings and the guitar body is examined experimentally and by means of numerical simulation. An experimental setup not only capable of determining eigenmodes and eigenfrequencies but also demonstrating the transient coupling between the strings and the body is presented. This capability is achieved with a plucking mechanism that allows realistic and reproducible plucks of a single string and synchronized measurements of multiple plucks at different positions of the guitar body using a scanning laser Doppler vibrometer. Besides the experimental setup, a finite element model of the guitar is developed. The numerical model consists of the strings, the body, and the neck of the guitar. Furthermore, the struts reinforcing the soundboard and the back of the guitar are included. A comparison between the numerical model and the experimental measurements is conducted with particular focus on the transient coupling between the strings and the soundboard.
	Thai Fiddle Saw-u Modeled as a Helmholtz Resonator with Circular Membrane Kajornpop Toboonchuay, Munhum Park, Bhanupol Klongratog [Abstract] Saw-u is a Thai low-pitched vertical fiddle, of which two strings are bowed to vibrate, via a bridge, a sheet of goatskin or cowhide stretched over a cavity with sound holes. This instrument is similar to Cambodian Tro-u, but distinguished from Chinese Yehu or Korean Haegeum in that animal skin is used for the interface to the bridge (rather than wood in the latter two). In the current study, the unique structure of the instrument body was investigated by establishing a mathematical model where the cavity was assumed to behave as a Helmholtz resonator interacting with a circular membrane. Two coupled equations governing the motions of the membrane and that of the air mass in the soundhole were solved based on simple assumptions. The results showed that the resonance frequencies associated with the circular modes of the membrane were shifted under the influence of the Helmholtz resonator, whereas that of the resonator would remain unchanged. Moreover, it was found that an additional circular mode may be observed near the Helmholtz resonance frequency, which may significantly influence the sound quality by reinforcing the resonance. The application of the current findings to the analysis of similar structures will also be discussed.
	Finite Element Modelling of Japanese Koto Strings Kimi Coaldrake [Abstract] The development of a high resolution finite element model of the Japanese koto has been previously reported. The koto is a plucked zither made of paulownia wood and 1.83m in length. Its 13 strings are made of polyester fibre and supported by 13 moveable bridges approximately 6cm high. A functional representation of each string was included in the high resolution model by using a wave form that entered the koto sounding body at a signal point where the bridge would be located for the standard (hirajōshi) tuning. Correlation between spectra generated in the model and spectra of an actual instrument as played provided initial observations of string behavior. This study aims to improve the fidelity of the spectral response by directly coupling the string to the resonating body. A beam model and a truss model with the dimensions of a professional string that is pre-tensioned to yield a close approximation of strings on an actual instrument are studied. The nature of the boundary conditions at either end of the string is discussed. Simulation results from the two models as compared to notes played on the koto used as the basis of the finite element modeling are reported.

	The Impulse Pattern Formulation (IPF) as a nonlinear model of musical instruments Simon Linke, Rolf Bader, Robert Mores [Abstract] The Impulse Pattern Formulation (IPF) is a top-down method proposed previously (Bader, R.: Nonlinearities and Synchronization in Musical Acoustics and Music Psychology, 2013) which assumes musical instruments to work with impulses which are produced at a generator, travel through the instrument, are reflected at various positions, are exponentially damped and finally trigger or at least interact with succeeding impulses produced by the generator. The underlying recursive equation relates every new system state to previous values and their logarithm. Adding more system components increases the number of reflection points, thus the number of terms in the argument of the logarithmic function increases. Like other nonlinear equations, the IPF can produce stable states but also bifurcation and divergency and fully captures transitions between regular periodicity at nominal pitch, bifurcation scenarios, and noise. Applying the IPF on musical Instruments, the nonlinear behavior like transients or multiphonics can be described, which would be very complicated or impossible using well-established methods such as modal analysis or finite element models. Furthermore, the IPF is used for sound synthesis which follows the fundamental principles of real musical instruments and, due to the simple mathematical description of the IPF, needs a very limited amount of input parameters.
	MAESSTRO: a sound synthesis framework for Computer-Aided Design of piano soundboards Benjamin Elie, Xavier Boutillon, Juliette Chabassier, Kerem Ege, Bernard Laulagnet, Benjamin Trévisan, Benjamin Cotté, Nicolas Chauvat [Abstract] The design of pianos is mainly based on empirical knowledge due to the lack of a tool that could predict sound changes induced by changes of the geometry and/or the mechanical properties of the soundboard. We present the framework of a program for the Computer-Aided Design of piano soundboards that is intended to bridge that gap by giving piano makers a tool to synthesize tones of virtual pianos. The sound synthesis is solely based on physical models of the instrument in playing situation. The calculation of the sound is split in several modules: computation of the modal basis of the stiffened soundboard, computation of the string dynamics, simulation of the soundboard dynamics in reaction to the string excitation, and calculation of the sound radiation. Reference tests of sound synthesis of real pianos as well as sound synthesis of modified pianos are used to assess our main objective, namely to reflect faithfully structural modifications in the produced sound, and thus to make this tool helpful for both piano makers and researchers of the musical acoustics community.
	Navier-Stokes-Based Physical Modeling of the Clarinet Nicholas J. Giordano, Jared W. Thacker [Abstract] Direct numerical solutions of the Navier-Stokes equations have been used to model the recorder, trumpet, and clarinet. This first-principles approach to calculating the air flow through a wind instrument allows the investigation of a number issues that are difficult or impossible to address with more approximate modeling. The power of this kind of model is illustrated in studies of (1) how the labium position in a recorder affects the tonal properties, (2) qualitative failure of the Bernoulli equation in calculations of the pressure near the lips of a trumpet player, and (3) the dynamics of a clarinet reed. Work supported by NSF grant PHY1513273.

	Non-destructive measurement of the pressure waveform and the reflection coefficient in a flue organ pipe Viktor Hruska, Pavel Dlask, Milan Gustar [Abstract] A multiple-microphone method employed for in-duct acoustics applications is adapted for a flue organ pipe geometry. In order to make the measurement non-destructive the microphones are replaced by a pressure probe synchronized with a reference signal. Limits of the method regarding the pipe geometry are verified by the numerical calculations employing the linearized Euler equations. Results based on the lossless model, the visco-thermal lossess and models regarding the convection and turbulence are compared and discussed. A framework for the reflection coefficient calculation is designed and tested.
	Temporal Acuity - Flamenco Guitar versus Classical Spanish Guitar Robert Mores [Abstract] Other than classical Spanish guitars, flamenco guitars are capable of projecting rapid beat sequences in pronounced clarity. This relates to what musicians call a fast guitar. This ask for fast attack but also for some kind of damping in between beats, which may follow each other densely by some ten milliseconds in a rasgueado. Temporal features are investigated across guitars of both types to understand whether the flamenco guitar differs from the classical guitar in these aspects. The full data set contains impulse responses for more than 60 valuable reference guitars. Attack and decay are extracted from bridge impulse responses and from playing open strings. Additionally, a simple measure represents the speed of sound development across the soundboard. This measure is derived from multi-point impulse responses taken along the soundboard. Populations of both types of guitars strongly overlap in these temporal maps and the physics seem to provide only part of the answer. Flamenco guitars tend to be faster in the treble range when monitored by means of specific temporal loudness. While there is only little done on modeling phase-dependent sound perception, auditory physiology may provide the other part of the answer.
	Measurement-Based Comparison of Marimba Bar Modal Behaviour Douglas Beaton, Gary Scavone [Abstract] A marimba bar’s modal behaviour is governed by the shape of its ëundercut’. Manufacturers typically shape these undercuts to tune up to three modes for specified frequencies. With only three or fewer partials to tune, numerous bar geometries may yield the desired results. Different manufacturers will employ different techniques to arrive at suitable bar geometries. This diversity in tuning approaches, coupled with the natural variability of wood, results in a multitude of undercut shapes. Two bars may produce the same musical note despite plainly visible differences in undercut geometry. This work uses experimental modal analysis to investigate the variability of marimba bar modal behaviour. Measurements are performed on numerous bars of the same note. Geometric data, including overall dimensions and mass, are recorded for each bar. Several manufacturers are represented in the resulting data set, including Yamaha, Musser and Marimba One. Variability of the tuned and untuned modal frequencies are of primary interest. Untuned torsional modes may compromise bar performance if their frequencies are near those of the tuned modes. The proximity of these untuned mode frequencies to those of the tuned modes is therefore also investigated. Results are presented comparing bar performance both between brands and within a brand.
	Analysis of reed vibrations and mouthpiece pressure in contemporary bass clarinet playing techniques Peter Mallinger, Montserrat Pàmies-Vilà, Vasileios Chatziioannou, Alex Hofmann [Abstract] While articulation on the B♭ clarinet has already been a subject of various studies, articulation on the bass clarinet has received less attention. Because of the increasing interest for using the bass clarinet, especially in contemporary music, this instrument is emerging from the shadow of the B♭ clarinet. In order to investigate articulation on the bass clarinet an experiment was carried out in an anechoic chamber at the University of Music and Performing Arts Vienna. A professional clarinetist was recorded performing different articulation techniques on a German bass clarinet under controlled performance conditions. Results show that the attack transients on the bass clarinet were about 0.085 s long in staccato articulation. In comparison, attack transients on the B♭ clarinet are 2 to 3 times shorter. This study especially focuses on the slap tonguing technique. Of particular interest is the reed displacement signal, which shows the movement of the reed. It has been observed that tones articulated with slap tonguing have a significantly shorter attack transient and are immediately entering the decay phase. Such measurements allow an in-depth analysis of player-instrument interactions with contemporary playing techniques and may support the refinement of physical model parameters but may also support music education.
	Relation between subjective evaluation for proficiency, expression or technique and acoustic feature on violin performance Madoka Okemoto, Masanobu Miura [Abstract] Studies of proficiency estimation for musical performance have been intensively conducted in the field of performance science.In most of the studies, feature parameters are calculated from sound of performance to estimate performance proficiency. However, most cases in such studies estimated only proficiency score, not for expressiveness or technique, that are considered as important for proficiency estimation. Therefore, this report tries to clarify a relation between effective acoustic parameters and scores of proficiency, expression or technique on violin performance. Moreover, most important parameters of each scores are discussed. Firstly, five professional violin players gave scores for proficiency, expressiveness and technique to 100 performances for simple major scale starting from 261Hz or C3 with vibrato. Then, a set of 98 parameters are calculated from the 100 performances. By using the parameters, scores for proficiency, expressiveness, and technique are estimated using liner regression with relative weights for each parameter, so that we confirmed the most effective parameters. As a result, most important parameters on each score are: FM vibrato parameters on proficiency, strength on attack for each note on expressiveness, and smoothness on consecutive two notes on technique. At the conference, authors will explain this result in detail on their presentation.
	Acoustical analysis of stringed instruments without touch Heidi Von Rüden, Anton Schlesinger [Abstract] At an abstracted level, the stringed instrument consists of a box with a neck and fastened strings. The parameter of the resonator, the material and construction features determine the sound. Therefore the acoustic measurement of instruments plays a prime role in conservation, for functional analysis and digital archiving. In this contribution an acoustical, contact-free measurement method for quantifying the transfer function of stringed instruments is presented. The method assesses the sounding body and its periphery by means of a standard acoustical impulse response measurement (AIR) in an anechoic room. As a test signal a logarithmic sweep is employed that offers a high signal to noise ratio and the ability to separate potential harmonic distortion of the electronic signal chain from the impulse response of the instrument. The measurement is compared to the hammer probe, which is the current gold standard method. AIR is an ideal tool for functional analysis, long term monitoring of instruments as well as quality control. Instruments are not subjected to mechanical stress and do not have to be prepared for play. The sonification of the impulse response allows for aural assessment and may complement as well as standardize the description of digital objects in archives.
	Evaluating the role of the cutoff frequency on sound production of clarinet-like resonators using digital synthesis Erik Alan Petersen, Philippe Guillemain, Jean Kergomard [Abstract] The impedance cutoff frequency due to the network of open toneholes is a well-known characteristic of woodwind instruments. Benade remarks that the frequency at which cutoff occurs is strongly related to the sound of an instrument and that it correlates to the adjectives musicians use to describe the character of a given instrument. However, it is not known how the cutoff frequency impacts the competition between the energy that facilitates the auto-oscillation of the reed and the energy that is radiated from the resonator. To evaluate the effects on sound production and radiation, simplified resonators with the same first impedance peak frequency, but different cutoff frequencies, are conceived and experimentally verified. It is found that both a rigorous geometrical and acoustic regularity result in a very strong cutoff behavior. Next, digital synthesis is used to simulate the pressure and velocity waveforms within the mouthpiece of resonators with different cutoff frequencies. Spectral characteristics of the resulting waveforms can be used to quantify how the cutoff frequency affects sound production.
	On the use of reed-to-room transfer function in bassoon auralizations -  a listening test Timo Grothe, Stefanos Ioannou, Sebastià V. Amengual Garí [Abstract] The sound of a bassoon in a room can be convincingly synthesized from a reed mouthpiece pressure measurement, if the transfer function between the reed and a room position is known. We present an experimental setup which allows to measure such ”reed-to-room” transfer functions, with a bassoon fixed in playing position on stage and a binaural microphone on a seat in a concert hall. With measured mouthpiece pressure signals from a musician playing the fixed bassoon on stage, the synthesis results from convolving source signals with transfer functions can be compared to the corresponding measurements. We demonstrate results in the form of a listening test to investigate the auditory quality of these auralizations.
	Substitution of spruce tonewood with composite materials tailored using numerical models: an application to archtop guitars Romain Viala, Claudia Fritz, Vincent Placet, Emmanuel Foltete, Scott Cogan [Abstract] Stringed instrument making traditionally requires selected wooden materials, called tonewood. Numerous species are used, especially spruce and maple for domestic species and rosewood, ebony, mahogany and pernambuco for tropical ones. Nowadays, the shortage of sufficiently large trees as well as the impact of climate change has led to current and future supply issues. Multilateral treaties to protect endangered wood species are now including several of the above mentioned species, and may include more in the future. In parallel, during the last decade, composite materials made with natural fibres have increasingly been studied and used. The bio-based composites associate fibres from annually renewable sources and bulk wood cores with epoxy resin to create materials that exhibit adjustable mechanical properties. The long-term objective of this work is to demonstrate that such materials can be tailored to mimic the vibro-acoustical behaviour of tonewoods and seen as a sustainable solution. In this study, numerical models of stringed instruments are used to optimize the architecture of bio-based composites to copy the dynamic behaviour of a spruce archtop guitar soundboard. The dynamic response of the manufactured composite parts are measured and compared to the model predictions in order to validate the model-based recipes of composites.
	Proposal of a human-instrument interaction model and its basic examination using electromyogram Ryo Itoigawa [Abstract] In the production of musical instruments, prototypes are evaluated by professional performers. It is empirically known that evaluation of musical instruments differs depending on the evaluator. However, the mechanism how human evaluates a musical instrument is not revealed. In this research, we newly proposed a human-instrument interaction model when a person evaluates a musical instrument to reveal its mechanism. For a basic study of the model, we measured human muscle activity and verified its trend when controlling the plucking parameters for the guitar. In the experiment, 5 subjects were asked to play a simple task with a plectrum under control the plucking position and dynamics. Subjects consist 4 experienced amateurs and 1 beginner. EMG of four muscles considered to be involved in the plucking motion using a plectrum and audio from the front magnetic pickup were measured simultaneously. As a result, the muscle activity due to the difference in the position has a large difference for each subject, and no specific trend was observed. The muscle activity due to the difference in the dynamics was found to have a certain tendency among subjects, such as muscle activity also increases and decreases with the increase and decrease of plucking dynamics.
	The ObieAlto project: looking for correlations between perceptual properties and constructional data Claudia Fritz, Valérian Fraisse, Danièle Dubois [Abstract] While the outline geometry differs slightly between violins, it can vary considerably between violas, which are less standardised. During the 2016 Oberlin workshop (organised by the Violin Society of America), a group of instrument makers have collectively designed the so-called ObieAlto outline. 25 violas were then built following this model, but without any other constraint. They were gathered and mounted with the same set of strings at the 2017 workshop. Two short excerpts (respectively in the low and high registers) were recorded by a professional player in a recording studio. The recordings were used in two listening tests, based on a free categorisation task : participants (20 makers and 10 violists) had to evaluate the similarities and differences between the instruments. Statistical and linguistic analyses showed a large variability between the participants but groups of instruments sharing relatively consensual features could be identified. Very few direct relationships between these perceptual features and physical parameters (constructional data but as well audio descriptors calculated on the recordings and vibro- acoustical measurements) could be observed, showing that the multiplicity of the parameters available during the building process allow instrument makers to obtain a certain set of perceptual properties with very different strategies.
	Tuning of membranophone based on visualization of membrane vibration mode Eri Zempo, Naoto Wakatsuki, Koichi Mizutani, Yuka Maeda [Abstract] Tuning of membranophones is important to design timbre, while it is difficult for inexperienced players, due to the insufficient ability for judgment of pitch difference. In this paper, we propose tuning scheme for membranophones, substituting visual information for auditory information. First, vibration modes shape of the head membrane are visualized, based on the measurement of sound pressure on the head membrane by a circular microphone array, and we estimate the tension distribution of the head membrane, especially unbalance in tightness of the pair of rods on oppositional position, make the nodal line of the (1,1) vibration mode change. Second, we propose a tuning scheme for membranophones based on information on the state of the nodal lines of the mode shapes, visualized based on the microphone measurements, and the difference of eigenfrequencies between the orthogonal modes. We show that the proposed scheme is helpful to make the head tension uniform, as the results of experiments using the vibration of tom-tom with only one side head stretched as an example of actual membranophones. We expect this scheme to train the tuning ability for inexperienced players.
	Non-contact measurement of bow force and friction force in bowed string instruments using a camera Ryodai Izaki, Naoto Wakatsuki, Koichi Mizutani, Keiichi Zempo [Abstract] Visualizing the mechanical parameters given by the player to the instrument may help to improve the performance technique. Thus, the methods to measure parameters that have less influence on musical performance are required. In this research, we proposed a non-contact measurement method of bow force and friction force using an ordinary camera (not high speed). By using an ordinary camera instead of a high-speed camera, we can obtain the average position of the strings from the blurred image. The process consists of the following 3 steps: (1) Taking the video of illuminated strings with a camera. (2) The position of the strings is calculated from the center of gravity illuminated part. (3) String displacement from a neutral position is converted into bow force and friction force using the relation between position and force in a string. In addition, this method is possible to visualize the bow force and frictional force with real-time, so a player can check it there. We confirmed the validity of the proposed method by a verification experiment.
	Time-domain response measurement of the trumpet, and the room Timo Grothe [Abstract] The bell of a trumpet is a flaring horn which has two functions: on the one hand, it terminates the resonating bore and therefore controls the sound reflections traveling back to the mouthpiece. On the other hand, the bell controls the impedance match between the narrow downstream bore and the surrounding air in a room, and the radiation directivity. The cylindrical bore downstream of the mouthpiece can favor non- linear wave steepening: The ”brassiness” of the sound perceived in the room depends on the amplitude of the pressure peaks inside the mouthpiece. To investigate these phenomena sound pressure measurements have been performed on a trumpet, with sensors inside the mouthpiece, and at different distances from the bell using ”musical” excitation signals (generated by a trumpeter) and pulselike technical excitation signals, at various levels.
	Timbre and Duration of Attack Depend on the Amount of Reverberation Tor Halmrast [Abstract] The attack of a signal is of course best preserved if we hear the direct sound only, but that is not the case even in a small room. Musicians know how long reverberation masks the next onset, but more astonishing is the prolongation of the attack, also for a first note in a phrase. The paper will present theory regarding how diffuse field reverberation influences the attack. The early response of a concert hall, is, however, seldom ”diffuse”, and it is shown that introducing early reflection can reduce the smoothening from the reverberation. The paper shows measurements of attack from the Integrated Squared Step Response, for both real halls and simulations, and for signals of different lengths and for different musical instruments. Very short notes/clicks/xylophone gets almost no prolongation of the attack due to reverberation. Medium long notes get prolonged attack, which makes them sound somewhat less brilliant. For double bass arco etc. with long note on-set, the attack is also prolonged, but the timbre might be even smoother and more pleasant. Preserving the attack is important because listeners nowadays are used to recordings where any wanted amount of direct sound is mixed with a late, long smooth, non-correlated reverberation.
	High resolution 3D radiation measurements on the bassoon Timo Grothe, Malte Kob [Abstract] Musical wind instruments with tone-holes have complex radiation patterns. Since openings act as sound sources, depending on their relative distance and phase soundwave superposition can lead to boosts or cancellations at different observation points. These phenomena are particularly prominent in the bassoon, as a multitude of differently sized tone-holes are distributed irregularly across a long, bent corpus. To extend our knowledge on pitch-related directivity patterns of such complex instruments the bassoon was chosen as a test case measurement object for a high resolution radiation measurement in 3D, using a repeatable, artificial excitation and a 2 axis turntable. We compare the radiation patterns of three different tonehole configurations, and discuss implications for simultaneous measurements with a microphone array.
	Study of the effect of acoustic sound bridges on wind instruments: Perceptual study with a panel of trumpet players Jean-François Petiot [Abstract] The study of the quality of a musical instrument, as perceived by the musician, is a complex problem. Many subtle phenomena are involved and several devices, or materials, are proposed to musicians, with a noticeable commercial success for some of them. We are interested in a particular device: sound bridges for wind instruments (made of two plates, clipped at a joint of a wind instrument with a rubber band). The objective of the work is to study if audible differences, due to the presence of the sound bridges, can be highlighted during trumpet playing. An ABX test was carried out with a panel of 5 trumpet players with various levels (from professional to advanced amateur) and various use degrees of the bridges in their practice (from always to not user). After a training phase, musicians were blinded and asked to answer to several repetitions of the ABX test in free playing conditions. Results were analyzed with the binomial distribution and the Signal Detection Theory (SDT). In addition, several repetitions of different notes were recorded with and without the bridges. A spectral analysis was carried out to test whether or not a significant effect of the acoustic bridges can be highlighted.
	How the Directivity of Bundengan Affects Its Musical Performance Indraswari Kusumaningtyas, Raymond Christianto, Gea O. F. Parikesit, Rosie H. Cook, Muhammad S. Abdulloh, Luqmanul Chakim, Mulyani Moelya, Nicole A. Tse, Margaret J. Kartomi, G. R. Lono Lastoro Simatupang [Abstract] The bundengan is a traditional musical instrument from Indonesia that has a half-dome structure, and uses clipped strings and long, thin bamboo plates to generate metal-like and drum-like sounds, respectively. In our previous study, we have unraveled the physics of the clipped strings. However, the interaction between the strings and the half-dome resonator has been largely unknown. In this study, we investigate this interaction, particularly by measuring the directivity of the bundengan as the string vibrations are amplified by the resonator. We performed two sets of measurements, where the instrument was played by traditional and contemporary artists, respectively. This quantitative data complement our interviews with, and qualitative observations on, the artists to provide a comprehensive insight on how the directivity affects the musical performance of the bundengan. Our results open new possibilities for the sustainability of this endangered instrument, as the quantitative analysis allows the makers and players to further enhance the instrument’s musical performance.
	Feasibility Study of Computational Environment for Assisting Musical Instrument Manufacturing Guilherme Orelli Paiva, Rodolfo Thomazelli, Guilherme Nishino Fontebasso, Lucas Neves Egidio [Abstract] The musical instruments manufacturing requires several project demands related to the instrument structural capacity and to the desired aesthetic and sound attributes. Although technologies to support these projects have been available for at least two decades, most of what has been done is the empirical reproduction of consolidated models, which hinders innovations since it is often based on trial and error methods. Computational tools, therefore, are useful because they may provide a certain prediction level of the instrument structural behavior and its sound, leading to time and costs reduction in the instrument project. In this context, the Urutau project is emerging as a computational enviroment for assisting musical instrument manufacturers. This work presents a preliminary architecture of the Urutau enviroment as well as an objective validation study of its simulation tools. Initially, a simplified monochord is built and its corresponding CAD model is obtained. A finite element modal analysis is then performed and results are compared with experimental data. A physical modelling based on a modal approach associated with a finite-difference solution is used to generate a set of monochord synthesized sounds which are compared objectively to real sounds.
	Damping of waves at the walls of a conical tube Cornelis Johannes Nederveen, Timo Grothe, Johannes Baumgart [Abstract] Resonators of reed wind instruments are tubular ducts with one open and one closed end. The ratio of pressure response to flow excitation at the closed end is the input impedance. Resonance frequencies of the duct are near to peaks in the impedance spectrum. Damping due to visco-thermal effects at the walls influences the frequency and the magnitude of the impedance-spectrum peaks, which influence intonation, playing behaviour and timbre. For cylindrical instruments theory to account for wall losses is available and experimentally confirmed. The wave equation in a conical tube while accounting for dissipative effects at the walls appears to be complicated. Four approximative solutions are compared: (1) Nederveen (1969) presented an approximate analytical solution while neglecting some higher order terms. (2) a transmission line method mimicking the conical pipe as a series of short conical (or cylindrical) pipes, (3) directly solving the equation with a Runge-Kutta procedure, (4) applying a finite difference method. For a ”simplified bassoon” (a perfect cone of 3000 mm length, input diameter 4.2 mm, output diameter 46.9 mm) the four methods give different results. Measurements are planned, but the narrow tube entrance and smoothness requirements make a high accuracy difficult. Suggestions are welcome.
	Non-Linearities of the mechano-electrical tonegenerator of the Hammond Organ Malte Münster, Florian Pfeifle [Abstract] The Hammond Organ with its electro-magnetic generator, still a standard instrument in the western music world. This organ still fullfills the musicians’ demand for assertiveness and a distinctive sonic identity with intuitive control of some arbitrary parameters. Bequeathed a heritage of some hundreds of thousands of tonewheel organs to the world, most of them still in service since the original manufacturer went out of business. The worldwide organ scene is still vivid. A description of the tone production mechanism is presented based on measurements taken on different instruments, like Model A and T-Models and includes high-speed camera measurement and tracking of the generator and key mechanisms as well as oscilloscope recordings of the amplifier chain. Some properties emerge due to the interaction of the mechanical motion of interaction with the magnetic H-field. Some non-linear effects like leakage between wheels, changes in the complexion of harmonics and at least amplifier distortion areexamined. A FEM model of the respective geometry showing good accordance with the proposed effects. A simplified FDM-model is written and a more complex physical model having a special regard to the geometry and electronic parts of the sound production mechanism.

Design of a mechanical player system for fatigue-life evaluation of woodwind reeds Connor Kemp, Song Wang, Gary Scavone [Abstract] Research into the vibrational properties of woodwind reeds, and potential synthetic replacements, requires the consideration of several factors. To date, analysis of pertinent properties of natural cane reeds has mostly been limited to reeds in their initial ”unplayed” state. One important mechanical aspect of reed-life and durability that should be considered is fatigue behaviour. Fatigue is concerned with the degradation of mechanical stiffness over the lifespan of a reed and is important for understanding changing vibrational behaviour. It is also likely that reed properties reach a steady-state after initial playing, but before they begin to significantly degrade, with mechanical properties (elastic, damping) during this period being most important for synthetic material development. Here an artificial player system is developed and used to evaluate the long-term mechanical behaviour of cane reeds. Reeds are ”played” on the system with control over playing time, input pressure and playing frequency. In this way, the dependency of mechanical fatigue on frequency is evaluated. During the study, reeds are also tested under static bending conditions to characterise mechanical degradation rates. Results will aid in understanding the importance of playing time and frequency on reed lifespan, properties, degradation and potentially lead to comparisons with current synthetic reeds.

The player-reed interaction during note transitions in the clarinet Montserrat Pàmies-Vilà, Alex Hofmann, Vasileios Chatziioannou [Abstract] When playing woodwind instruments, most of the player’s control over the instrument takes place inside the player’s mouth. Blowing pressure, tonguing strategies, embouchure and vocal tract configuration are modified during playing to perform expressively. Aiming at analysing the player’s actions at the note transitions, an experiment with eleven clarinet players was carried out. The mouth pressure, the mouthpiece pressure and the reed oscillation were recorded in order to track blowing and tonguing actions and to identify vocal tract adjustments. The influence of the player’s actions on the sound was quantified by considering the note attack and release transients. The results showed in which manner the players adapt tonguing and blowing actions according to the articulation style (legato, portato, staccato), the tempo and the dynamics of the music. The tonguing technique in portato articulation was consistent among players, whereas different techniques were observed for staccato articulation. The influence of the vocal tract on the attack transients was proven to be non-negligible and it was dependent on the clarinet register. Particularly at high pitches, some players showed vocal tract adjustments that supported shorter attack transients.

Measurement and Modeling of a Resonator Guitar Mark Rau, Julius Smith [Abstract] Resonator guitars are acoustic instruments which have one or more spun metal cones embedded in the top plate, with the strings driving the cone directly through a bridge. They were originally designed to be louder than traditional acoustic guitars and are often played with a metal slide. The vibrational characteristics of resonator guitars having a single inverted-cone are studied as the basis for a synthesis model. The small-signal input admittance is obtained using an impact hammer and laser Doppler vibrometer. As well, sinusoidal sweeps are made using a modal shaker at various driving amplitude levels. The shaker measurements show that some of the modes exhibit nonlinear characteristics which can be modeled using the Duffing equation. These measurements can serve as a basis for a digital waveguide model of the resonator guitar.

Modelling of Gabonese harps Antoine Caillon, Jean-Loïc Le Carrou, Baptiste Chomette, Sylvie Le Bomin [Abstract] Traditional instruments handed down from generation to generation, Gabonese harps have various shapes, often anthropomorphic, that depending on the population and the region concerned. Nevertheless, harps are all composed of eight strings, each wrapped up on one side to a tuning peg fixed on the neck and at the other side linked to a wooden tailpiece. It is often nailed to both ends of the resonance box, under the soundboard made of animal skin. In order to study the evolution of these instruments within the framework of a multidisciplinary project, an acoustic modelling of the instrument is undertaken. The main objective of this modelling is to understand and highlight maker’s elements that predominate in their sound. For this purpose, the Udwadia- Kalaba formulation is used to model vibrating systems coupled together by mechanical constraints. In particular, this formulation can take into account geometrical non-linearities of strings induced by their high-amplitude excitation. Model parameters were first extracted from an instrument at our disposal. Then, time-domain simulations were confronted to experimental data. Finally, a parametrical study showed that the low string tension and modal behaviour of the tailpiece are of great importance in the characteristic sound of the instrument.

	Design, Construction, and Material of an Ancient Indian String Instrument Anurag Gupta, Chaitali Dangarikar [Abstract] Ekatantri Vina is a one-stringed fretless tubular zither from ancient India whose descriptions and representations are variously found in musicological texts and sculptures, respectively, between 10th and 15th century AD. The present work is a first of its kind attempt to study these sources to understand the precise structural and material nature of the Vina. In particular, we use the five Sanskrit texts where Ekatantri Vina is unambiguously described, and prepare accurate computed aided models of various parts of the Vina as well as describe their assembly. We also compare how the construction and the material of the Vina differed between various texts which span five centuries. Our work is motivated, on one hand, from an aim to establish historicity of certain unique design features of the present day Indian stringed instruments and, on the other hand, to initiate a systematic study towards reconstruction of ancient Indian instruments. Our investigations also provide grounds for further study in acoustics, mechanics, and materials, all in the context of ancient Indian science.
	Vibration Characteristics of Oud Soundboard Sinan Inanli, M. Ercan Altinsoy [Abstract] Oud is a plucked musical instrument played in many countries. This historical musical instrument involves many structural parts effecting its acoustics and sound quality. This study aims at investigating the vibration characteristics of an oud soundboard for free-free and fixed (at its edges and no back cavity) boundary conditions. Also as a final step, the soundboard-air cavity coupled modes were measured by assembling the soundboard and body together. Frequency response function (FRF) measurements were carried out by experimental modal analysis technique to reveal the dynamic behaviour (mode frequencies, mode shapes and damping coefficients) of the soundboard which has a conventional seven parallel strutting configuration.
	Numerical Simulation of Aerodynamics Sound in an Ocarina Model Hiroaki Okada, Sho Iwagami, Taizo Kobayashi, Kin'Ya Takahashi [Abstract] The body of an ocarina is regarded as a Helmholtz resonator. Thus, we can expect differences in sounding mechanism between ocarinas and other air-jet instruments with a resonance pipe. Furthermore, ocarinas are driven by cross blowing like transverse flutes so that the driving mechanism with an air-jet should be different from that for vertical flues like a recorder. In this paper, we numerically explore the sounding mechanism of an ocarina from the view point of aeroacoustics with compressible fluid simulation. We adopt compressible LES as a numerical scheme of compressible fluid, which simultaneously reproduces fluid and acoustic fields and with which we can investigate the interaction between the fluid and acoustic fields near the mouth opening. Our 3D model has numerical grids more than one hundred and 50 million to reproduce detail behavior of air-jet motion, vortices and acoustic filed near the mouth opening. We numerically observed an acoustic oscillation with the Helmholtz resonance frequency in the body together with the detail structure of fluid field.

Influence of Long-Term Playing on the Tonal Characteristics of a Concert Piano - an Observational Study Niko Plath [Abstract] Well-maintained pianos are said to ”mature” and to ”change to the better” over the first years. When auditioning concert pianos for purchase, technicians do often not choose the best sounding instrument but the one with the greatest potential for future development. The present work addresses the following questions: Are structural changes measurable on a piano after one year of operation in a concert house? Are these changes perceivable by listeners? Measurements are performed on two occasions: First, on a brand new instrument prepared for sale. Second, on the same piano after having been played for one year in a concert hall. Single notes are recorded with dummy-head-microphones in player position in an anechoic chamber. An extended ABX listening test engaging approx. 100 players, tuners, and builders, addresses the questions whether a variation in tonal quality is audible and if so, what sound properties could lead to a perceived difference. Semantic sub-grouping allows for indication on the vocabulary listeners of varying expertise use to verbalize their sensation. The statements give hints on what could have changed over the year and are used as a basis for the analysis of corresponding physical properties and psychoacoustic parameters related to the described sensations.

Perception-based classification of Expressive Musical Terms: Toward a parametrization of musical expressiveness Aviel Sulem, Ehud Bodner, Noam Amir [Abstract] Expressive Musical Terms (EMTs) are commonly used by composers as verbal descriptions of musical expressiveness that performers are requested to convey. In order to classify 55 EMTs covering a wide range of characters on the basis of their perception by performers, we conducted two experiments with the participation of 11 professional string players. They were asked (i) to organize the considered EMTs in a two- dimensional plane in such a way that proximity reflects similarity; (ii) to rate these EMTs in terms of valence, arousal, extraversion and neuroticism, on 7-level Likert scales. Using a minimization procedure, we found that a satisfactory partition requires these EMTs to be organized in four clusters (whose centers are associated with tenderness, happiness, anger and sadness) located in the four quarters of the valence-arousal plane of the Russell’s circumplex model of affect. An alternative representation is provided by the positive-negative activation parameters, introduced by Watson & Tellegen and corresponding to the coordinates along the diagonal directions of the valence-arousal plane. We obtained for these EMTs a significant correlation between positive activation and extraversion and between negative activation and neuroticism. This demonstrates that the expressed emotion is strongly related to the musical character of the performance.

Session chair(s):

V. Fréour, YAMAHA, Marseille M. Jousserand, Buffet Crampon, Mantes-La-Ville

	Exploring dependency between instrument design and musician's control Patricio De La Cuadra, Augustin Ernoult, Benoit Fabre [Abstract] In flute-like instruments the pitch of the notes produced depend on the instrument geometry as well as on the control the musician exerts on it. Thus, a particular flute design requires from the musician a specific strategy to obtain a set of notes ”in tune” with a certain cultural intonation agreement. The control parameters available in most flutes include the jet speed and the opening of one end of the flute, normally adjusted by the proximity from the lips to the labium. In this paper we explore the relationship between the design of the instrument and the control exerted by the musician, proposing algorithms to automatically design the bore geometry and position and size of the toneholes for different musicians control strategies.
	A Real-Time Physical Model to Simulate Player Control in Woodwind Instruments Vasileios Chatziioannou, Alex Hofmann, Sebastian Schmutzhard [Abstract] The interaction between woodwind players and their instruments is a key aspect of expressive music performance. Therefore, recent studies have focused on understanding how the actions of the players affect sound generation. Based on experimental results obtained using both human performers and an artificial blowing machine, this paper presents a numerical model that, taking the players’ actions into account, may synthesise expressive woodwind instrument sounds. Implemented in C++ the model allows real-time performance on a standard desktop computer, thus enabling the user to modify the model parameters in a live performance scenario. Apart from varying parameters related to the embouchure of the player and the effective length of the resonator (i.e. mimicking modifications that could take place in real playing) this model also allows virtual modifications that would not be possible to realize in the physical world, such as a cone gradually morphing into a cylinder and vice versa. Besides parameters related to the excitation mechanism and the geometry of the instrument, the user is able to modify the properties of the air inside the instrument and the magnitude of the viscothermal losses.
	The virtual workshop OpenWInD: towards an optimal design tool of wind instruments for makers Guillaume Castera, Juliette Chabassier, Augustin Ernoult, Alexis Thibault, Robin Tournemenne [Abstract] Our project develops an optimisation software (OpenWind) for wind instrument making. The approach is based on a strong interaction with makers and musicians, aiming at defining interesting criteria that should be optimized, from their point of view. After a quantitative transcription of these criteria, under the form of a cost function and a design parameter space, we implement state-of-the-art numerical techniques (finite elements method (FEM), full waveform inversion (FWI), various optimisation techniques) with a flexible framework (in terms of models, formulations, coupling terms...) in order to solve the optimisation problem. More precisely, we exploit the fact that the sound waves inside the instruments are solution to acoustic equations in pipes, which gives us access to the full waveform inversion technique, that can be used in both time and frequency domains. The chosen methodologies weekly depend on the criterion and can be adapted to multiple physical situations (non constant temperature, multimodal decomposition in the pipe, coupling with an embouchure, ...), which can therefore be modified a posteriori. The goal is to proceed iteratively between the instrument makers and the numerical optimisation tool (openwind) in order to achieve, finally, criteria that are representative in terms of instrument tone and ease of playing.

Session chair(s):

V. Fréour, YAMAHA, Marseille M. Jousserand, Buffet Crampon, Mantes-La-Ville

	Optimization of Marimba Bar Geometry by 3D Finite Element Analysis Douglas Beaton, Gary Scavone [Abstract] The natural frequencies of marimba bars are tuned by removing material from the bottom of the bar. Three partials are typically tuned, though less are tuned for higher notes. With only three or fewer partials to tune, many different bar geometries may produce the desired frequencies. As a result, bar geometries can show significant variation between brands, with each manufacturer employing their own tuning approach, honed over many years of experience. This work uses 3D finite element analysis to investigate tuning marimba bar geometry, with an aim to inform manufacturing methods. Optimization techniques, including genetic algorithms, are employed to evaluate and improve bar geometries. The preferred geometries tune the desired frequencies, while also scoring well on secondary evaluation criteria. These secondary criteria include: separating the frequencies of torsional modes from those of the tuned modes, prioritizing symmetry, and producing shapes similar to professional marimba bars. Models are developed using the open-source finite element program Calculix. Optimization routines are written in Python. The programs are interfaced to coordinate model execution. Functions are created to identify mode shapes based on displaced geometry. These functions provide resilience against any modal reordering, allowing the optimization routines to run unsupervised over significant changes in geometry.
	How to include several acoustic characteristics in the design of woodwind instruments? Augustin Ernoult, Samy Missoum, Philippe Guillemain, Christophe Vergez, Michael Jousserand [Abstract] When manufacturers design woodwind instruments, they must simultaneously adjust multiple aspects of the resonator response. The same resonator is used to play several notes by opening or closing tone-holes, and, for some instruments, the same fingering is used to play several registers. From an acoustic point of view, it means that several characteristics of the input impedance must be simultaneously adjusted: at least the first two resonance frequencies of each fingering. The acoustic models can predict the input impedance from the geometry of an instrument with good confidence. This suggests the possibility to solve the inverse problem through optimization algorithm: obtain the geometry having the desired input impedance. However, this inverse problem necessitates the optimization of several acoustic characteristics by modifying dozens geometric parameters (radius and position of the tone holes, chimney height, etc). A specific strategy is therefore necessary to solve this problem. A collaboration between manufacturers from Buffet Crampon and acousticians led to the development of an optimization tool to aid in the design of new woodwind instruments. The strategy adopted in this tool will be presented and applied to an illustrative problem: the construction of a pentatonic clarinet.
	Model-based quantification of the effect of wood modifications on the dynamics of the violin Romain Viala, Sarah Lämmlein, Vincent Placet, Scott Cogan [Abstract] The building of musical instruments is traditionally based on craftsmanship and selection of materials. Instrument makers generally attribute a dominant role to the material properties in regard with the acoustics of the musical instruments. Numerous methods are studied by both researchers and instrument makers to modify the physical and mechanical properties of tonewoods. The density, elastic and damping parameters are of particular interest. Wood properties can be modified through chemical treatments, fungi attacks, or climatic artificial aging and results can already be found for spruce, maple and ebony woods. Meanwhile, these methods increase the cost of wood preparation and the objective assessment of the impact of these wood modifications on the perception of musical instruments and especially the improvement of their ”quality” remains a subject to discussion. Physics-based models of musical instruments are now able to simulate their complex vibroacoustical behaviour. A numerical model is used to investigate the impact of wood property modifications on the dynamics of a violin while taking into account irreducible uncertainties in the material properties. The aim is to establish a threshold for wood treatments that will insure an observable impact on the dynamic behaviors of interest above and beyond the irreducible material variability.

Session chair(s):

V. Fréour, YAMAHA, Marseille M. Jousserand, Buffet Crampon, Mantes-La-Ville

	Numerical analysis and comparison of brass instruments by continuation Vincent Fréour, Hideyuki Masuda, Satoshi Usa, Eiji Tominaga, Yutaka Tohgi, Bruno Cochelin, Christophe Vergez [Abstract] Brass instrument design has long been relying on empirical know-how, build up over the years by the craftsmen. Some relationships between the air-column geometry, the intonation and some attributes of sound color have been formalized through this process by the makers. However, many properties of the instrument, related to timbre, dynamic range, playability, etc. are still very difficult to correlate to the design. Alongside these issues and important questions for the craftsmen, the knowledge in the acoustics of musical instruments has extensively improved in the last decades, benefiting especially from cutting edge engineering methods for the analysis of dynamic systems. In this presentation, we will detail some applications of stability analysis and continuation (Asymptotic Numerical Method), to physical models of trumpets. This approach aims to clarify differences between instruments on the basis of calculated performance descriptors. On a longer term, our goal is to include these technologies in the development of new instruments, by providing some virtual performance analyzers for the design of brass instruments.
	Numerical synthesis applied to reed instruments: influence of the control parameter transients on the steady-state oscillation regime Tom Colinot, Philippe Guillemain, Jean-Baptiste Doc, Christophe Vergez [Abstract] Physical models of self-oscillating musical instruments include strongly nonlinear elements and delayed terms, leading to a great variety of produced sounds. For example, the same fingering on a wind instrument can produce oscillating regimes at several different fundamental frequencies as well as quasi-periodic regimes. The emergence of these regimes is conditioned mostly by the value of control parameters, representing the action of the musician, such as blowing pressure or lip force on the reed. As a strongly non-linear delayed system, a wind instrument model may converge to different stable regimes depending on the initial conditions and the transient of the control parameters. For the second point, an example would be the speed with which the blowing pressure reaches its final value. In this work, we show that depending on the way the blowing pressure increases to its final value, the steady regime may be oscillating or non oscillating, or correspond to the first or second register. Such considerations are useful when trying to predict the playability of an instrument using numerical simulations.
	Simulation of the nonlinear characteristic of the clarinet exciter and of the side holes Pierre-André Taillard, Jean-Pierre Dalmont [Abstract] At the last ISMA, a method for measuring the nonlinear characteristic and the static mechanical behaviour of the clarinet exciter (reed + mouthpiece + lip of the player) was presented. Here, we show how this measured behaviour can be integrated in a real time simulation using a waveguide clarinet model, including nonlinear losses at the toneholes. The clear separation of the aeraulic (nonlinear characteristic) and mechanical (static bending of the reed against the mouthpiece lay, like a stiffening spring) aspects allows a straightforward, piecewise simulation of the dynamic behaviour, apparently without any numerical stability problem. For the simulation of the instrument, at a low sound level, the proposed empirical tonehole model tends towards the linear radiation impedance, whereas at high level, nonlinear losses dominate. They are modelled by Bernoulli’s law with turbulent flow (as for the exciter). Taking nonlinear losses into account is crucial for a credible simulation of the instrument, especially in the second regime. The model allows to realistically predict the playing frequency and the timbre of the instrument according to the two main objective factors characterizing clarinet reeds: stiffness and opening at rest (without lip pressure). This allows a virtual prototyping of the clarinet exciter and resonator.

Session chair(s):

V. Fréour, YAMAHA, Marseille M. Jousserand, Buffet Crampon, Mantes-La-Ville

	Numerical simulation of the acoustic guitar for virtual prototyping Henna Tahvanainen, Hideto Matsuda, Ryo Shinoda [Abstract] This research presents numerical simulation tools used in the research of acoustic guitars in the industrial context. The focus is on describing a virtual prototyping environment that has been successfully used in product development. The main challenge is achieving an acceptable agreement between simulation and measurement of a random guitar taken in the production line. To this end, detailed geometrical modeling and averaged materials parameters values measured from the production line are used. Simulation and measurement results are compared in terms of mode frequencies, frequency responses, and radiation efficiency.
	Creating Virtual Acoustic Replicas of Real Violins Esteban Maestre, Gary Scavone [Abstract] In the context of preserving historical musical instruments as interactive digital acoustic artifacts that can be played and heard in real time, we provide an overview of our recent progress on measuring, modeling, and virtually recreating the sound radiation characteristics of real acoustic violins. Our approach is based on measuring the directivity of an acoustic violin and constructing an efficient digital filter model that can be used for real-time processing of a whitened version of the electrical signal coming from a silent violin as played by a musician. In a low reverberation chamber, we use a microphone array to characterize the radiativity transfer function of a real violin by exciting the bridge with an impact hammer and measuring the acoustic pressure at 4320 points on a sphere surrounding the instrument. From the real violin measurements, we design a mutable state-space digital filter that allows to obtain the sound pressure radiated in any direction. We characterize the silent violin transfer function by exciting the bridge with an impact hammer and measuring the electrical signal at its output. From the silent violin measurement, we design a recursive parallel filter that allows to whiten the electrical signal and digitally recover the force signal.
	Generation and Analysis of a Database of Geometrical and Acoustic Properties for the Modern Almenräder-Heckel System Bassoons Vincent Houde-Turcotte [Abstract] The bassoon is one of the orchestral instruments that still requires further research in the field of musical acoustics and data on the instrument’s design is scarce. The main objective of this project is to provide a database of geometrical and acoustical properties measured on a large number of bassoons. Different types of data are included such as bore measurements obtained with a new automated measuring tool, tone hole positions/sizes/heights, impedance and sound pressure measurement with an artificial mouth and verbal description of the instrument’s timbral qualities and playability by the owners. Measurements are entered on the PAFI (Plateforme d’aide à la facture instrumentale), which will be available to all users. The theoretical digital model proposed by the platform can be refined on the basis of the comparison with the measurements. The long-term goals is to trace the evolution of the Almenräder-Heckel bassoon over the last century and also to propose a new design to instrument makers corresponding of an optimal middle ground between the different versions of this instrument, such as the long tone holes of the wing joint, which cause many acoustical issues while being essential to obtain the timbre desired nowadays by players worldwide.