Papers by Shigeru Yoshikawa
The prediction of changes in the perceived sound of a blown pipe due to wall vibrations is made d... more The prediction of changes in the perceived sound of a blown pipe due to wall vibrations is made difficult by the multitude of interactions. Excitation, shape, and sound radiation of structural modes depend on a number of parameters like material, voicing technique, geometry and fixing of the pipe. This article presents experimental work on comparison of vibrations and sound radiation from a tin-rich pipe in two cases: with damped and undamped wall vibrations. It was found out that changes in sound pressure level at certain frequencies in the spectrogram coincide with eigenfrequencies of both air modes and structural modes and thus support the assumption of mode coupling being responsible for sound changes.
Kashika Jōhō Gakkaishi, 2007
Proceedings of Meetings on Acoustics, 2013
ABSTRACT
IPSJ SIG Notes, Feb 21, 2003
Journal of the Acoustical Society of America, Jul 1, 2007
Two basic types of wood are used to make stringed musical instruments: woods for soundboards (top... more Two basic types of wood are used to make stringed musical instruments: woods for soundboards (top plates) and those for frame boards (back and side plates). A new way to classify the acoustical properties of woods and clearly separate these two groups is proposed in this paper. The transmission parameter (product of propagation speed and Q value of the longitudinal wave along the wood grain) and the antivibration parameter (wood density divided by the propagation speed along the wood grain) are introduced in the proposed classification scheme. Two regression lines, drawn for traditional woods, show the distinctly different functions required by soundboards and frame boards. These regression lines can serve as a reference to select the best substitute woods when traditional woods are not available. Moreover, some peculiarities of Japanese string instruments, which are made clear by comparing woods used for them with woods used for Western and Chinese instruments, are briefly discussed.
The radiation-directivity patterns of clarinets are measured using an artificial blowing system w... more The radiation-directivity patterns of clarinets are measured using an artificial blowing system which can ensure stable and reproducible tones. A reed is set in a box-shaped mouth and driven by the high-pressured air from an air compressor after adequately adjusting the embouchure formed by artificial lips made of silicone rubber. Our measurement in an anechoic chamber is carried out on three kinds of clarinets whose wall materials are grenadilla and ceramic by applying a common reed-mouthpiece setup. Lateral and circumferential directivity patterns are measured when all keys are untouched. A characteristic conical radiation is commonly indicated in lateral directivity patterns of three clarinets. Also, the effect of tone holes appreciably appears in circumferential directivity patterns measured near the clarinet center or in far field. However, that effect may be almost negligible in circumferential directivity measured near the barrel and bell. Proper improvements of the blowing system as well as careful applications of directivity measurement and near-field measurement will draw some correlations between the wall material and the radiated sound of the clarinet with tone holes closed.
Journal of the Acoustical Society of America, Feb 1, 1999
Three types of transient jet behaviors are demonstrated using slow-motion pictures (2 to 30 pictu... more Three types of transient jet behaviors are demonstrated using slow-motion pictures (2 to 30 pictures per second) taken by a high-speed digital video camera (1297 or 1440 pps). (1) The jet issuing from the flue almost always deviates toward the pipe outside and results in a large vortexlike trajectory. When the lower surface of this outwardly curved jet just touches the edge tip, a tiny vortex is likely to be formed beneath the edge. This vortex introduces the first stimulus from the jet to the pipe inside, and in turn significant disturbances are created along the jet. As communicated to the pipe, these disturbances gradually become periodic and well-organized to build a jet wave. This tiny vortex beneath the edge yields a smooth and fast build-up. (2) A much faster build-up is realized when the jet impinges the edge straightforwardly and divides into the two from the jet center. However, this case is rare. (3) A much slower build-up is caused when the blowing pressure is relatively low and a small vortex tends to stand between the flue and the edge. This stagnant vortex may yield a ‘‘two-crest’’ jet wave prior to the formation of an ordinal ‘‘one-crest’’ jet wave.
Journal of the Acoustical Society of America, Sep 1, 1993
Journal of the Acoustical Society of America, Apr 1, 1992
The jet works as not only an energy generator to drive the resonant pipe but also an energy colle... more The jet works as not only an energy generator to drive the resonant pipe but also an energy collector to maintain its wavelike vibration over the mouth. The jet may act virtually as a flexible thin diaphragm whether it bears the jet instability or not. Its overall lateral vibration then produces the acoustic mouth current, which must correspond to the feedback current collected by the jet in the jet-drive model [J. Acoust. Soc. Jpn. (E) 1, 175–191 (1980)]. Calculation of the acoustic impedance Z j′ of the jet as a vibrating diaphragm will help one understand how the jet vibration is sustained. Although the energy dissipation that occurred in the jet is much smaller than that in the pipe, the jet as well as the pipe should maintain its own oscillation according to the proper phase relation. In other words, the velocity of the jet diaphragm should be directed out of the mouth when the acoustic pressure is positive at the mouth. The question of whether the organ pipe sounds in water as well as in air was considered theoretically from the above viewpoint and was solved experimentally [J. Acoust. Soc. Jpn. (E) 5, 211–221 (1984)]. In spite of the great difference in fluid dynamical and acoustical properties between water and air, a small underwater organ pipe made of aluminum and driven by the water jet sounded at about 155 dB re: 1 μPa near 1 kHz. Similarities and differences between aerial and underwater organ pipes will also be discussed.
IntechOpen eBooks, Dec 9, 2020
Musical flue instruments such as the pipe organ and flute mainly consist of the acoustic pipe res... more Musical flue instruments such as the pipe organ and flute mainly consist of the acoustic pipe resonance and the jet impinging against the pipe edge. The edge tone is used to be considered as the energy source coupling to the pipe resonance. However, jet-drive models describing the complex jet/pipe interaction were proposed in the late 1960s. Such models were more developed and then improved to the discrete-vortex model and vortex-layer model by introducing fluid-dynamical viewpoint, particularly vortex sound theory on acoustic energy generation and dissipation. Generally, the discrete-vortex model is well applied to thick jets, while the jet-drive model and the vortex-layer model are valid to thin jets used in most flue instruments. The acoustically induced vortex (acoustic vortex) is observed near the amplitude saturation with the aid of flow visualization and is regarded as the final sound dissipation agent. On the other hand, vortex layers consisting of very small vortices along both sides of the jet are visualized by the phase-locked PIV and considered to generate the acceleration unbalance between both vortex layers that induces the jet wavy motion coupled with the pipe resonance. Vortices from the jet visualized by direct numerical simulations are briefly discussed.
Technical report of IEICE. EA, Nov 8, 2003
IPSJ SIG Notes, Feb 21, 2003
Journal of the Acoustical Society of America, Nov 1, 1988
This work investigates the performance of high-resolution beamforming techniques as used with aco... more This work investigates the performance of high-resolution beamforming techniques as used with acoustic arrays in shallow water. The maximum likelihood method (MLM) is the high-resolution technique of principal interest and the maximum entropy method (MEM) is addressed briefly. The topics dealt with are the
Journal of the Acoustical Society of America, Oct 1, 1996
Ab initio transfiguration of the jet disturbance at the sound initiation in organ flue pipes is c... more Ab initio transfiguration of the jet disturbance at the sound initiation in organ flue pipes is captured by visualizing a smoked jet with a digital high-speed video camera. The greatest interest centers on the ‘‘two-crest’’ mode of the jet wave disturbance appearing prior to the ‘‘one-crest’’ mode, which corresponds to the steady-state oscillation. This two-crest mode may be sustained by a ‘‘simultaneous double feedback’’: The lowest dominant frequency, which is lower than the first mode of the pipe resonance, is determined by the overall separation–reformation process of the two-crest jet; the second mode of th epipe resonance is simultaneously excited by the rear-crest jet after the two-crest jet is separated and a stagnant vorticity is formed at the mouth. Mode locking is not established between the harmonics until the two-crest mode has been transfigured into the one-crest mode. Moreover, a pictorial analysis of the steaady-state jet wave reveals that these experimental results of the phase speed and the amplification factor show excellent agreement with the theoretical results obtained from a spatial analysis of the jet instability.
Journal of the Acoustical Society of Japan. E, 1993
Journal of the Acoustical Society of America, May 1, 2013
It is well known that wave steepening and shock-wave formation due to nonlinear propagation throu... more It is well known that wave steepening and shock-wave formation due to nonlinear propagation through the bore are responsible for tonal brassiness of brass instruments. On the other hand, penetrating metallic tones are produced by hand-stopping the French horn. The present study demonstrates that the mechanism account for tonal metallicness of the French horn is nonlinear wall vibration of the bell. The measured waveforms of radiated pressure of the stopped tones indicate rapidly corrugating changes, which are not observed in brassy tones. Also, their spectra show much larger amplitudes of higher harmonics than those in normal mezzo-forte playing. The measurement of the wall vibration at the bell in hand stopping demonstrates similar characteristics. These results suggest that the bell wall vibration is responsible for the radiated tone color. Excitation experiments on the bell are carried out to elucidate the mechanism how the higher harmonic vibration is generated in hand stopping. They indicate that wall vibrations over 3 kHz are excited by the superharmonic generation derived from the geometrical nonlinearity of the bell. Moreover, for a direct support to our inference above, sound pressure of the stopped tone radiated when the horn bell is heavily damped will be examined.
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Papers by Shigeru Yoshikawa