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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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