Volume 110, Issue 1, July 2001
- acoustical news—usa
- book reviews
- reviews of acoustical patents
- advanced-degree dissertation abstracts
- general linear acoustics 
- nonlinear acoustics 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- transduction 
- structural acoustics and vibration 
- noise: its effects and control 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- music and musical instruments 
- bioacoustics 
- letters to the editor
Index of content:
- ACOUSTICAL NEWS—USA
- BOOK REVIEWS
- REVIEWS OF ACOUSTICAL PATENTS
110(2001); http://dx.doi.org/10.1121/1.4736960View Description Hide Description
The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet at http://www.uspto.gov.
- ADVANCED-DEGREE DISSERTATION ABSTRACTS
On the subjective responses based on the auditory-brain model in relation to the factors extracted from the interaural cross-correlation mechanism and the auto-correlation mechanism of sound fields110(2001); http://dx.doi.org/10.1121/1.4776783View Description Hide Description
Based on the auditory-brain model for subjective responses, the author investigated the relationship between several important subjective attributes of the sound field and the orthogonal factors that are extracted from both of the interaural cross-correlation function and the autocorrelation function. There are three significant findings. (1) The apparent source width (ASW) is described by two orthogonal spatial factors: the IACC and the width of the interaural cross-correlation function (). The scale value of ASW is formulated by superpositioning two terms: the 3/2 power of the IACC and the 1/2 power of the . (2) The most preferred delay time of a single reflection for a cello soloist can be calculated by the amplitude of the reflection and the minimum value of the effective duration of the running autocorrelation function of the music motifs played by the cellist. (3) From subjective preference tests by paired-comparison method, for different source locations on the stage in an actual concert hall, the subjective preference can be calculated using four orthogonal factors and the interaural time delay of the IACC ( ). When the IACC is not obtained at = 0, the preference scores decrease rapidly due to an image shift or an unbalanced sound field. Results agree well with the subjective preference obtained by use of simulated sound fields when = 0.
Thesis advisor: Yoichi Ando
Copies of this thesis written in English can be obtained from Shin-ichi Sato, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada, Kobe 657-8501 Japan. E-mail address: email@example.com.
110(2001); http://dx.doi.org/10.1121/1.4776784View Description Hide Description
Computational systems for design and diagnosis of sound field were developed. The concept of these systems are based on the model of human auditory-brain system [Y. Ando, Architectural Acoustics -Blending Sound Sources, Sound Fields, and Listeners (AIP/Springer-Verlag, New York, 1998)], including the autocorrelation mechanisms, interaural cross-correlation mechanism, and the specialization of the human cerebral hemispheres. Thesis consists of following four parts: (1) Computer simulation system for calculating the four orthogonal factors (, , and IACC) at each seat using architectural drawings were developed. The accuracy of this system were examined by comparing the calculated factors with the measured ones at Kirishima International Concert Hall. (2) The diagnostic system to measure the four orthogonal factors and additional factors (, and A-value) was developed. This system can be used for the measurement in the scalemodel. The effect of the reflectors' array above stage which can not calculate at the design stage was evaluated at the scalemodel measurement of Tsuyama music cultural hall. (3) As an application of the subjective preference theory, seat selection system to maximize the preference of each individual was developed. This system, which is installed in Kirishima International Concert Hall, can find the seat where the preference is maximized by the paired comparison test with respect to the four orthogonal factors. (4) Noise measurement system to measure and identify the environment noise using the factors extracted from the autocorrelation function ( (0), , and ) and the factors extracted from the interaural crosscorrelation function (IACC, , and ) was developed. As an example, noises from different car engines were characterized by these factors measured by this system.
Thesis advisor: Yoichi Ando
Copies of this thesis written in English can be obtained from Masatsugu Sakurai, Yoshimasa Electronic Inc., Daiichi-Nishiwaki Bldg., 1-58-10 Yoyogi, Shibuya, Tokyo, 151-0053 Japan. E-mail address: firstname.lastname@example.org.
110(2001); http://dx.doi.org/10.1121/1.4776785View Description Hide Description
Based on the theory of subjective preference, the author investigated the effects of the set of four orthogonal physical factors (listening level, initial time delay gap between the direct sound and the first reflection, subsequent reverberation time, and IACC) on the reverberance of sound fields. The study clarifies how much both temporal and spatial factors contribute to reverberance. Experiments were conducted to determine the effects of the physical factors on reverberance in simulated sound fields and in actual halls. Scale values of reverberance for both music and speech signals were obtained by the paired-comparison method. The results of these experiments show that these four factors affect the scale values of reverberance independently, and that the scale values of a sound field at any seat in a room can be calculated by the linear combinations of these factors. On the basis of the results from this and previous studies, some methods for controlling the reverberance of sound fields in an actual hall are proposed. The results of this study will allow the design of various reverberances for sound fields that are optimal for various source signals with its effective duration of autocorrelation function, .
Thesis advisor: Yoichi Ando
Copies of this thesis written in English can be obtained from Shigeo Hase, Theater Design Laboratory Co., 2-13-26 Makinohonmachi, Hirakata, Osaka, 573-1144 Japan. E-mail address: email@example.com
110(2001); http://dx.doi.org/10.1121/1.4776786View Description Hide Description
In order to synthesize both architectural design and acoustic design consisting of temporal and spatial design, a design process in which these elements are all considered is proposed in this study. Using this design process, a multi-purpose event hall, which is part of a larger architectural complex, was designed. This hall was measured for both temporal and spatial orthogonal factors after construction, with favorable results. One goal of this study was to solve the acoustic problems caused by the rounded shape of the event hall, where the architectural design had already been determined by the theme and concept of the complex. In a worst-case scenario, had the acoustic problems been solved without unduly affecting the architecture of the hall, the process would have been considered to be successful. Remarkably, some knowledge about methods to solve acoustic problems caused by the round shaped architecture was obtained through the design process blending architectural and acoustic factors.
Thesis advisor: Yoichi Ando
Copies of this thesis written in English can be obtained Akio Takatsu, Showa Sekkei Co., 1-2-1-800 Benten, Minato-ku, Osaka 552-0007, Japan.
110(2001); http://dx.doi.org/10.1121/1.4776787View Description Hide Description
Acoustical measurements and individual subjective evaluations for sound fields were performed based on a model of the human auditory-brain system and subjective preference theory. In the acoustic measurement section, orthogonal factors in historical opera houses and outdoor sound fields in forests are discussed. In the subjective evaluation section, individual differences and intra-individual changes of subjective preference are described in terms of the orthogonal factors. The main conclusions are as follows: (1) In acoustic measurements in a forest and in a bamboo forest, it is found that multiple scatteringeffects between trees or bamboo improve IACC; (2) Results of a preference test in an existing opera house show that subjective preference theory can be applied to opera houses, including the orchestra pit and the box seats; (3) Coefficient is introduced for individual preference in a sound field; and (4) The investigations of preference tests in relation to listening level () and subsequent reverberation time () for a simulated sound field show that subjects with a large value of α have small intra-individual changes, so the range of its preferred value is small. On the other hand, subjects with small value have minor preference as its parameter is changed.
Thesis advisor: Yoichi Ando
Copies of this thesis written in English can be obtained from Hiroyuki Sakai, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada, Kobe 657-8501 Japan. E-mail address: firstname.lastname@example.org.
110(2001); http://dx.doi.org/10.1121/1.4776788View Description Hide Description
The bandwidth-duration product, WT, is a fundamental parameter in most theories of aural amplitude discrimination of Gaussian noise. These theories predict that detectability is dependent on WT, but not on the individual values of bandwidth and duration. Due to the acoustical uncertainty principle, it is impossible to completely specify an acoustic waveform with both finite duration and finite bandwidth. An observer must decide how best to trade-off information in the time domain with information in the frequency domain. As Licklider (1963) states, “The nature of [the ear's] solution to the time-frequency problem is, in fact, one of the central problems in the psychology of hearing.” This problem is still unresolved, primarily due to observer inconsistency in experiments, which degrades performance making it difficult to compare models. The aim was to compare human observers' ability to trade bandwidth and duration, with simulated and theoretical observers. Human observers participated in a parametric study here the bandwidth and duration of 500 Hz noise waveforms was systematically varied for the same bandwidth-duration products (WT = 1, 2, and 4, where W varied over 2.5–160 Hz, and T varied over 400–6.25 ms, in octave steps). If observers can trade bandwidth and duration, detectability should be constant for the same WT. The observers replicated the experiments six times so that group operating characteristic (GOC) analysis could be used to reduce the effects of their inconsistent decision making. Asymptotic errorless performance was estimated by extrapolating results from the GOC analysis, as a function of replications added.
Three simulated ideal observers: the energy, envelope, and full-linear (band-pass filter, full-wave rectifier, and true integrator) detectors were compared with each other, with mathematical theory and with human observers. Asymptotic detectability relative to the full-linear detector indicates that human observers best detect signals with a bandwidth of 40-80 Hz and a duration of 50–100 ms, and that other values are traded off in approximately concentric ellipses of equal detectability. Human detectability of Gaussian noise was best modelled by the full-linear detector using a non-optimal filter. Comparing psychometric functions for this detector with human data shows many striking similarities, indicating that human observers can sometimes perform as well as an ideal observer, once their inconsistency is minimised. These results indicate that the human hearing system can trade bandwidth and duration of signals, but not optimally. This accounts for many of the disparate estimates of the critical band, rectifier, and temporal integrator, found in the literature, because (a) the critical band is adjustable, but has a minimum of 40-50 Hz, (b) the rectifier is linear, rather than square-law, and (c) the temporal integrator is either true or leaky with a very long time constant.
Thesis advisor: Dr. John K. Whitmore
Copies of this thesis can be obtained from Judi Lapsley Miller, NSMRL, Subase NLON Box 900, Groton, CT 06349-5000, E-mail: email@example.com or by downloading from 〈www.psychophysics.org〉.
- GENERAL LINEAR ACOUSTICS 
110(2001); http://dx.doi.org/10.1121/1.1379728View Description Hide Description
A detailed analysis is given of the energy and power measures associated with point sources which proceed along a rectilinear path in a prescribed and continuous manner that involves a limited period of acceleration. Attention is focused on monopole source types either singly or in pairs. The consideration of a single monopole precedes that of a “colliding” pair of such sources that have either equal or opposite source strengths. In all cases the angular and the joint angular and frequency distribution of the radiated energy, as well as the total radiated energy, are found at subsonic Mach numbers, and, for the paired sources, estimates are contingent on small Mach numbers. Numerical plots of the angular distributions are given, and applications of the analysis include the elementary modeling of the sound fields radiated by new aircrafts capable of completely reversing their course in minute distances.
110(2001); http://dx.doi.org/10.1121/1.1377051View Description Hide Description
A focusing technique based on the inversion of the propagation operator relating an array of transducers to a set of control points inside a medium was proposed in previous work [Tanter et al., J. Acoust. Soc. Am. 108, 223–234 (2000)] and is extended here to the time domain. As the inversion of the propagation operator is achieved both in space and time, this technique allows calculation of the set of temporal signals to be emitted by each element of the array in order to optimally focus on a chosen control point. This broadband inversion process takes advantage of the singular-value decomposition of the propagation operator in the Fourier domain. The physical meaning of this decomposition is explained in a homogeneous medium. In particular, a definition of the number of degrees of freedom necessary to define the acoustic field generated by an array of limited aperture in a focal plane of limited extent is given. This number corresponds to the number of independent signals that can be created in the focal area both in space and time. In this paper, this broadband inverse-focusing technique is compared in homogeneous media with the classical focusing achieved by simple geometrical considerations but also with time-reversal focusing. It is shown that, even in a simple medium, slight differences appear between these three focusing strategies. In the companion paper [Aubry et al., J. Acoust. Soc. Am. 110, 48–58 (2001)] the three focusing techniques are compared in heterogeneous, absorbing, or complex media where classical focusing is strongly degraded. The strong improvement achieved by the spatio-temporal inverse-filter technique emphasizes the great potential of multiple-channel systems having the ability to apply completely different signal waveforms on each transducer of the array. The application of this focusing technique could be of great interest in various ultrasonic fields such as medical imaging, nondestructive testing, and underwater acoustics.
Optimal focusing by spatio-temporal inverse filter. II. Experiments. Application to focusing through absorbing and reverberating media110(2001); http://dx.doi.org/10.1121/1.1377052View Description Hide Description
To focus ultrasonic waves in an unknown heterogeneous medium using a phased array, one has to calculate the optimal set of signals to be applied on the transducers of the array. (In most applications of ultrasound,medical imaging,medical therapy, nondestructive testing, the first step consists of focusing a broadband ultrasound beam deeply inside the medium to be investigated.) Focusing in a homogeneous medium simply requires to compensate for the varying focus–array elements geometrical distances. Nevertheless, heterogeneities in the medium, in terms of speed of sound, density, or absorption, may strongly degrade the focusing. Different techniques have been developed in order to correct such aberrations induced by heterogeneous media (time reversal, speckle brightness, for example). In the companion to this paper, a new broadband focusing technique was investigated: the spatio-temporal inverse filter. Experimental results obtained in various media, such as reverberating and absorbing media, are presented here. In particular, intraplate echoes suppression and high-quality focusing through a human skull, as well as hyper-resolution in a reverberating medium, will be shown. It is important to notice that all these experiments were performed with fully programmable multichannel electronics whose use is required to fully exploit the spatio-temporal technique.
110(2001); http://dx.doi.org/10.1121/1.1378347View Description Hide Description
It is shown that the secular equation for Rayleigh waves propagating on a viscoelastic half-space always admits only one complex root corresponding to a surface wave. This result is proved in those cases in which the displacement field can be obtained analytically, including the isotropic case. The root is obtained in terms of complex integrals extending to the viscoelastic case, a result by Nkemzi [Wave Motion 26, 199–205 (1997)]. The wave solution is shown to represent an admissible surface wave for any viscoelastic relaxation kernel compatible with thermodynamics. A correspondence is then established between elastic and viscoelasticRayleigh waves and their propagation properties are pointed out by an approximated analysis of the solution. Illustrative results are given by a numerical evaluation of the complex root for anisotropicviscoelastic half-spaces.
110(2001); http://dx.doi.org/10.1121/1.1380440View Description Hide Description
Three-dimensional elastic wave-field calculation is addressed for the case of orthotropic materials with arbitrary spatial orientation. Based on a mathematical formulation involving Green’s dyadic displacement tensor function, appropriate evaluation yields a representation of the displacement vector of transducer wave fields in anisotropic media which is convenient for effective numerical computation. With respect to bulk wave propagation, the numerical evaluation of Green’s dyadic function is circumvented by applying a reciprocity-based approach, which is valid in the (point source) far field. The presented formulation involves characteristic quantities obtained from plane-wave theory and appears as a point-source superposition representation including the respective point-source directivities. Thus, it is in the same form as a corresponding formulation for scattered elastic wave fields presented previously [M. Spies, J. Acoust. Soc. Am. 107, 2755–2759 (2000)]. Focusing on orthotropic composite materials, numerical evaluation examples are presented for ultrasonic tranducer field patterns and time-dependent radio frequency (rf)-pulse propagation.
110(2001); http://dx.doi.org/10.1121/1.1373447View Description Hide Description
Previous investigations have used Hankel transforms to establish the amplitudes of the wave fields resulting from arbitrary angle impingement on a circular orifice in a baffle. Investigations have also been undertaken on the effects of model coupling between the higher modes in the orifice. In particular, these studies concentrated on establishing the contributions at the cut-on wave number for a particular mode. This work is extended to introduce a method of simply approximating the complex amplitude of the forward and backward waves in the duct at the cut-on wave number, based only on the modal wave number. The interest focuses on the cut-on wave number because the forcing functions for the various fields will be at a maximum at cut-on. This technique is established by observing the relationships between the peak values of the driving functions and the modal wave number. If simple approximations are established for the in-duct field, it is also possible to approximate the maximum amplitude of the scattered field.
110(2001); http://dx.doi.org/10.1121/1.1378348View Description Hide Description
Although there have been many investigations employing the continuous wavelet transform for the analysis of dispersive waves, they seem to lack theoretical justifications for the effectiveness of the continuous wavelet transform (CWT) over other time–frequency analysis tools such as the short-time Fourier transform(STFT). The goal in this paper is to offer theoretical and experimental justifications for its effectiveness by comparing the performance of CWT and STFT in terms of their time–frequency analysis capabilities of certain dispersive elastic waves. The waves in consideration are elastic flexural waves generated by an impact in a solid circular cylinder. The ridge analysis procedure is employed to estimate instantaneous frequencies by CWT and STFT. Although in the present investigation we are focused on a limited class of dispersive waves, it gives an insight into the effectiveness of CWT for the analysis of other types of dispersive wave systems.
- NONLINEAR ACOUSTICS 
Numerical modeling of finite-amplitude sound beams: Shock formation in the near field of a cw plane piston source110(2001); http://dx.doi.org/10.1121/1.1369097View Description Hide Description
Two theoretical models and the corresponding numerical codes for the description of nonlinear acoustic beams radiated from intense cw sources in water are presented. In the first model, diffraction effects are included using the Rayleigh integral, whereas nonlinearity and thermoviscous absorption are accounted for in a quasi-plane approximation. The simulations are performed in the time domain using the code previously developed for single-pulse propagation in medium having arbitrary frequency-dependent absorption. The second model is based on the Khokhlov–Zabolotskaya–Kuznetsov equation, which, contrary to the first model, accounts for diffraction in the parabolic approximation. The simulations are performed in the frequency domain using a novel algorithm that has been developed. A variable number of harmonics, which follows the nonlinear broadening of the wave spectrum are employed in the algorithm to speed up calculations. In order to prove the validity and the accuracy of the two codes developed, the simulation of diffraction and nonlinear effects in the near field of an intense ultrasound circular piston source in water is performed. The results of modeling obtained by both codes are compared with each other and with known experimental data, and are found to be in a good agreement. Frequency-domain code is then used for detailed study of the strongly nonlinear regime of propagation, when shocks are developed in the waveform close to the source. It is demonstrated that diffraction plays a major role in shock formation. Development of two shocks in each cycle and their further collision is predicted. It is also shown that nonlinear propagation and shock formation result at some distance in the two times excess of peak positive pressure in comparison with the maximum value obtained in the case of linear propagation. The beam total power decay due to formation of shocks as a function of the propagation distance is compared with the intensity in a plane wave propagation without diffraction. It is shown that nonlinear energy decay starts earlier for the beam, but decreases slower over longer distances.
110(2001); http://dx.doi.org/10.1121/1.1379080View Description Hide Description
The frequency response of a nonlinear acoustical resonator is investigated analytically and numerically. The cross-sectional area is assumed to vary slowly but otherwise arbitrarily along the axis of the resonator, such that the Webster horn equation provides a reasonable one-dimensional model in the linear approximation. First, perturbation theory is used to derive an asymptotic formula for the natural frequencies as a function of resonator shape. The solution shows that each natural frequency can be shifted independently via appropriate spatial modulation of the resonator wall. Numerical calculations for resonators of different shapes establish the limits of the asymptotic formula. Second, the nonlinear interactions of modes in the resonator are investigated with Lagrangian mechanics. An analytical result is obtained for the amplitude-frequency response curve and nonlinear resonance frequency shift for the fundamental mode. For a resonator driven at its lowest natural frequency, it is found that whether hardening or softening behavior occurs depends primarily on whether the nonlinearly generated second-harmonic frequency is greater or less than the second natural frequency of the resonator. A fully nonlinear one-dimensional numerical code is used to verify the analytical result.
110(2001); http://dx.doi.org/10.1121/1.1379086View Description Hide Description
Nonlinear interaction of two plane acoustic waves in the (0,0) mode of a square duct is investigated from the viewpoint of chaotic dynamics. Phase-space portraits are reconstructed from time series obtained in an experiment. It is demonstrated that limit sets formed by the phase space trajectories are “attractors.” The largest Lyapunov exponent and correlation dimension of these attractors are calculated, and the results indicate that these attractors are chaotic.
110(2001); http://dx.doi.org/10.1121/1.1375844View Description Hide Description
The nonlinear mechanical properies of an electrolytic, electroacoustic cell have been analyzed. Three main nonlinear mechanisms are present. (1) The nonlinear electric current in a circuit with a time-varying capacitance of the electrical double layer, modulated by the applied electric voltage. (2) The nonlinear time dependencies of the ion charges and of the local conductance at the interface membrane solution, governed by a Boltzmann distribution of the ion concentration. (3) The quadratic electrostatic forces of attraction, exciting a second acoustic harmonic. The interplay of these mechanisms is complicated. An analytical expression for the time dependence of the membrane displacements of the electroacoustic cell is obtained and the harmonics amplitudes are analyzed by numerical evaluations.