bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of stimulus level and background noise on vowel representations in the auditory brain stem of cats
Authors: May Bradford J. , Sachs Murray B.
Published: July 2002

Effects of stimulus level and background noise on vowel representations in the ventral cochlear nucleus (VCN) were investigated by recording single-unit discharge rates in anesthetized cats. The quality of vowel encoding by populations of neurons can be evaluated by plotting vowel-driven rates as a function of each unit’s best frequency (BF, the most sensitive frequency); the resulting rate profiles are assumed to show good representations of formant structure if there are high driven rates at BFs near formant frequencies and low rates at BFs near spectral troughs. Among the VCN unit types recorded in the present study, chopper units exhibited the most detectable formant-to-trough rate differences across vowel levels and in background noise. By contrast, primarylike units produced vowel representations that reflected the limited dynamic range of auditory-nerve fibers [May et al., Aud. Neurosci. 3, 135–162 (1996)]. Primarylike units with low spontaneous rates (SR<18 sp/s) showed better representations than high SR primarylike units, but failed to respond at low vowel levels. These results suggest that peripheral representations of speech sounds are sharpened by patterns of auditory nerve convergence in the cochlear nucleus. [Work supported by NIDCD Grant No. DC00109.]
The effect of fast-acting compression on psychoacoustic jnd’s
Authors: Edwards Brent W.
Published: July 2002

Fast-acting compression is used in hearing aids to compensate for loudness recruitment in patients with sensorineural hearing loss. Intensity difference limens are independent of the slope of the loudness function and it has been argued that compression normalizes loudness perception in hearing-impaired individuals at the expense of their intensity discrimination performance. Similar arguments have been made with regard to the effect of fast-acting compression on envelopes: Compression reduces the magnitude of envelope fluctuations and thus impairs the near-normal temporal processing capabilities of hearing-impaired individuals. The exact consequences of compression on these perceptual abilities are not clear, however, due to the level- and depth-dependent thresholds of intensity and modulation discrimination tasks, respectively. The effect of fast-acting compression will be quantified in terms of these psychophysical tasks and the results will be related to the speech recognition performance of hearing-impaired individuals.
Spectro-temporal modulation transfer and speech intelligibility for multiband amplitude compression
Authors: Festen Joost M.
Published: July 2002

For ears with sensorineural hearing loss the growth of loudness with stimulus level is often larger than in normal ears. This phenomenon is called recruitment. To restore normal loudness perception and to fit speech in the limited dynamic range of an impaired ear many modern hearing aids apply some form of multiband amplitude compression. However, within the cochlea nonlinearity and frequency selectivity are closely linked and therefore recruitment often goes together with reduced frequency selectivity. While compression may correct the recruitment, it does not improve the frequency selectivity. The opposite is even more correct; multichannel compression reduces the spectro-temporal variations in speech. Therefore in terms of speech intelligibility, the net effect of compression is difficult to predict. In an experiment speech intelligibility after multiband compression in quiet and in noise for 16 hearing-impaired listeners was measured. For each individual listener the speech spectrum was shaped and presented monaurally halfway in the ear’s dynamic range in all conditions. Results show a decrease in intelligibility with both increasing compression ratio and increasing number of channels. These results can be fitted with a single curve when intelligibility is plotted as a function of the transfer of phase-locked modulations in time and frequenc.
Selection of a tonotopic scale for vowels
Authors: Nearey Terrance M.
Published: July 2002

Various distinct tonotopic scales (e.g., log frequency, ERB, Bark) have been used for the representation of fundamental and formant frequency data for vowels. In previous work in our laboratories [T. Nearey, Proc. ICSLP92, 583–586 (1992)], generalized linear modeling was used to assess the relative appropriateness of these scales on both production measurement and vowel categorization data on each scale using several alternative vowel normalization schemes. That work focused on F0 and F1 and used the classic data of Peterson and Barney [G. Peterson and H. Barney, J. Acoust. Soc. Am. 24, 175–184 (1952)]. Analysis of that data suggested that the log scale as provided somewhat better fits to the data with less evidence of violations of modeling assumptions. However, results in modeling perceptual data (from Canadian English listeners) were less clear. The present study will extend the scope of the earlier work by examining more data and expanding the statistical modeling framework. The production analyses will be augmented using an additional large production data set for another dialect of American English [J. Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099–3111 (1995)]. The perceptual analyses will be augmented using additional perceptual data sets collected in our laboratories.
Syllable as the segmentation unit in perceiving spoken Chinese
Authors: Tseng Chin-Hsing
Published: July 2002

How spoken Chinese is segmented by native speakers has been addressed by the author in recent years. Evidence has accumulated to support the view that the syllable is the level at which speakers segment their spoken language. Earlier studies found that Mandarin–Chinese phonemes were detected faster in real syllables than in nonexistent syllables, that they were faster for level-tone and falling-tone syllables than for rising-tone or dipping-tone syllables, and that structural complexity had no effect on phoneme detection. These effects have preempted phoneme and word as the segmentation unit in real-time processing. This study was designed to investigate the role of stress foot in segmentation, to discover the locus of the tone effect, and to replicate the tone and complexity effects with Taiwanese speech materials. Stress assignment and phoneme detection tasks were employed as the experimental paradigms. The results indicated that stress assignment in Mandarin is not consistent enough to warrant a stress-foot segmentation procedure, that the tone effect originates from syllable duration variations, and that earlier effects were replicated with Taiwanese.
Evidence of independent verbal processors for the same stimulus: Insights from dichotic verbal transformations
Authors: Bashford James A. , Warren Richard M.
Published: July 2002

A clearly enunciated word heard repeating without change undergoes illusory verbal transformations (VTs) to different words or syllables. Surprisingly, when a repeating word is delivered dichotically with an interaural asynchrony of half its duration, the separate lateralized images of the word are heard to undergo independent VTs (e.g., ‘‘commence’’ heard at one ear while ‘‘tress’’ is heard at the other) [see Warren and Ackroff, Nature 259, 475–477 (1976)]. The present study eliminates a peripheral explanation attributing such independent changes to lateral asymmetries in repetition effects upon the lower auditory pathways, which might provide conflicting acoustic-phonetic information to a single verbal processor. A dichotic alternation paradigm, in which successive statements of a repeating word were presented to opposite ears (e.g., ‘‘flame’’ presented left, then ‘‘flame’’ presented right...) was also found to produce independent VTs. However, when higher amplitude noise was presented to the ear opposite the alternating speech signal, contralateral induction [Warren and Bashford, Percept. Psychophys. 20, 380–386 (1976)] produced diffuse medial localization of the otherwise lateralized signals, and despite monaural verbal stimulation, VTs were linked across ears. This and other evidence to be discussed demonstrate independent preattentive verbal processors for spatially distinct sources. [Work supported by NIH.]
Inducing a ‘‘perceptual magnet’’-like effect in a nonspeech modality
Authors: Husain Fatima , Guenther Frank H.
Published: July 2002

Kuhl and colleagues have described a ‘‘perceptual magnet effect’’ in which subjects show a decreased ability to discriminate between vowel-like stimuli when these stimuli fall near a prototypical vowel from their native language. Guenther and Gjaja [J. Acoust. Soc. Am. 100, 1111–1121 (1996)] proposed that the effect results from experience-based map formation in auditory brain regions. Because this model attributes the effect to neural mechanisms that have been identified in cortical areas subserving different sensory modalities, it predicts that it should be possible to induce magnet effects in nonspeech modalities. To test this, adult subjects’ discrimination sensitivities to narrow-band noise stimuli were tested before and after training sessions meant to approximate an infant’s exposure to speech sounds. Training consisted of a categorization task that preferentially exposed subjects to stimuli from a small frequency range meant to correspond to a prototypical vowel. Sensitivity tests after training revealed that subjects had become worse at discriminating sounds within this ‘‘prototype’’ range as compared to a ‘‘nonprototype’’ range that was absent during training. This suggests that the magnet effect may not depend on phonetic processing and may reflect neural mechanisms common to different sensory modalities. [Supported by NIDCD and the Sloan Foundation.]
The effect of speaking style alterations on locus equation stability
Authors: Sussman Harvey M. , Dalston Eileen , Gumpert Sam
Published: July 2002

Locus equations, as a phonetic descriptor of stop place of production, have been systematically investigated across speakers, gender, languages, perturbation conditions, syllable position, and manner class. As locus equation slope is thought to directly reflect the extent of anticipatory coarticulation of the vowel on the prevocalic consonant, changes in coarticulation as brought about by altered speaking styles can effectively alter locus equation descriptors of stop place. This study attempted to assess the stability of locus equations within each speaker as citation-style hyperarticulation was compared relative to spontaneous, hypoarticulated output. Twenty speakers, ten male and ten female served as subjects. Traditional citation-style locus equations were generated from productions of CV /t/ words printed on lists with initial /bdg/ followed by ten medial vowel contexts. Locus equations were also derived from spontaneous speech output which was generated by rapid reading of discourse-like passages constructed to resemble normal conversational speech, but with numerous lexical items beginning with /bdg/ in many vowel contexts. Spectral analysis was performed with the Kay Elemetrics CSL system. Comparisons of slopes, y intercepts, R2, and standard error of estimates across the two speaking conditions will be presented and discussed.
Three-dimensional Doppler ultrasound: A tool for the 21st century
Authors: Martin Roy W. , Leotta Dan , Li Xiang-Ning , Hausken Trygve
Published: July 2002

Three-dimensional (3-D) ultrasound now offers a method to overcome former limitations of two-dimensional (2-D) Doppler. Important 3-D areas include the spatial delineation of the patency and pathways of blood vessels as well as the measurement of flow in them. In our laboratory a variety of 3-D uses has been investigated: detection and mapping of coronary arteries (3-D power Doppler, in vitro), mitral valve regurgitation (3-D color Doppler, in vitro and in vivo), and gastric flow (3-D color Doppler, in vivo). Several different 3-D approaches have been applied and results will be presented. However, in the future, it is believed that direct flow measurement can be achieved. Flow is equal to the integral of the velocities normal to a surface that cuts through a flow field. An arc of constant radius in a 2-D-sector scanner will inscribe an arc of a spherical surface, if rotated around the origin of the sector (e.g., multiplane transesophageal echocardiogram). The pulsed Doppler signals along the circumference of the inscribed arc represent the velocities normal to that surface. Integration of these velocities should provide direct measurement of the flow field cutting this inscribed surface. Algorithms for testing this strategy are under development.
Low-frequency calibration in water-filled pipes
Authors: Luker L. D. , Zalesak J. F.
Published: July 2002

For many years the Underwater Sound Reference Division has developed ever more powerful means for creating desired sound fields inside water-filled pipes in order to calibrate transducers. Early efforts resulted in manually controlled calibration chambers approximately 2 m long, creating standing-wave fields or traveling-wave fields propagating along the axis of the pipe at frequencies from 0.1 to 4000 Hz. These calibrators have been modified in recent years to measure also the acoustic properties of material samples and the wave fields are now computer controlled. These systems were followed by pipe-shaped calibrators that are submerged in troughs of water for checking towed-array sensor elements. The latest calibrator to be developed is the Long-Line Hydrophone Calibrator (LLHC). This calibrator has a chamber length of 57 m and is capable of calibrating hydrophone line arrays up to 49 m long at temperatures from 2 to 35°C and hydrostatic pressures up to 6.9 MPa. The LLHC uses transducers distributed along its length to provide wave fields equivalent to plane waves arriving from any angle of incidence at frequencies from 5 to 700 Hz. Research is currently underway to increase the frequency range of the LLHC to above 200 Hz. [Work supported by ONR.]
A flexible analysis/synthesis tool for transient signals
Authors: Verma Tony S. , Meng Teresa H. Y.
Published: July 2002

An overview of a flexible analysis/synthesis tool for transient signals that effectively extends the spectral modeling synthesis (SMS) parametrization of signals from sinusoids+noise to sinusoids+transients+noise is given. The extended model, by explicitly handling transients, provides a more realistic and robust signal analysis/transformation/synthesis tool. Although others have pointed out the need for partitioning SMS into sinusoids+transients+noise, they have not provided a flexible model for transients. The need for an explicit transient model arises because SMS analyzes a signal by first modeling the sinusoidal components of the signal. SMS then subtracts these sinusoidal components from the original signal leaving a residual signal that contains transients+noise. One drawback of SMS is it models this transient+noise residual solely as filtered noise. Our transient model, when used on this residual, first detects where possible transients occur, models the transients, then removes transients from the signal. This leaves a second residual that is slowly varying noise. Attacks are well preserved by the transient model and the noise model now works more effectively. Becuase the transient model is the frequency domain dual to sinusoidal modeling, it retains flexibility and allows for a wide range of signal transformations.
Sound representation and modification with multiresolution sinusoidal models
Authors: Goodwin Michael , Pradoni Paolo , Vetterli Martin
Published: July 2002

In the standard sinusoidal model, the analysis and synthesis are typically carried out at fixed frame rates. This can result in representation error for signals with dynamic behavior. To improve the modeling performance for such signals, the sinusoidal analysis-synthesis can be carried out in a multiresolution framework based either on a filter bank structure or on adaptive time segmentation. In the latter method, which will be of primary interest here, the adaptation is guided by a metric such as rate-distortion. Such an approach improves the model accuracy while preserving the ability to carry out the rich class of modifications afforded by the standard sinusoidal model.
Cavitation bubble dynamics induced by ultrasound waves
Authors: Laborde J-L. , Bouyer C. , Caltagirone J-P. , Gérard A.
Published: July 2002

Propagation of power ultrasound (from 20 to 800 kHz) through a liquid initiates a not-so-well-known phenomenon called acoustic cavitation. Inceptions and germs grow into bubbles which collapse, possibly giving rise to extreme conditions of temperature and pressure (assessed to be up to 10 000 K and 500 atm). For instance, these conditions initiate and greatly enhance chemical reactions. A high-speed film shot at 500 fps clearly identifies stable and transient cavitation and shows bubble population phenomena. Clouds of bubbles grow up to ten times their emergence size during 15 ms, and move at velocity around 50 cm/s. Mathematical modeling is performed as a new approach to predict where active bubbles are and how intense cavitation is. Then, a first computation, based on Euler’s linear acoustic equations, is used to calculate the pressure field in the case of a cylindrical sonoreactor. A second calculation based on fluid dynamics equations is undertaken as CFD codes are very interesting because they also provide velocity and temperature fields, and two phase flows (liquid and bubbles) could be modeled. The comparison with experimental observations (photographs, high-speed film) and measurements (Particule Image Velocity, temperature) shows good agreement with both calculations.
Enhancement of acoustic cavitation effects by simultaneous multifrequency excitation
Authors: Fang Qiping , He Beixing , Lin Zhongmao
Published: July 2002

Acoustic cavitation can produce many effects. Promoting or inhibiting cavitation depends on different practical purposes. The production of as many cavitation activities as possible is always expected in sonochemistry. Here, the enhancement of acoustic cavitation effects by simultaneous multifrequency excitation, with frequencies in the power ultrasound ranges (20–100 kHz), is studied. One ultrasonic transducer is used to produce multiple ultrasonic frequencies at the same time, rather than several transducers which work at respective frequencies. A probe hydrophone is utilized to measure the subharmonic emission of cavitation and distribution of the acoustic field. The chemical effect of cavitation is determined by the method of iodine release. The results show that simultaneous multifrequency excitation can reduce the cavitation threshold and enhance the chemical effect of cavitation. On the basis of the cavitation bubble dynamics theory, the theoretical analysis proposed attempts to explain this phenomenon, and further discussions are presented. [Work supported by National Natural Science Foundation of China.]
Study of a volcano-profiled ultrasound field
Authors: Du Gonghuan , Wang Enyu , Zhang Yu
Published: July 2002

As is known, the volcano-profiled ultrasound field is of interest in the application of ultrasonic therapy for cancer. This paper indicates that when the radial distribution of vibration velocity on the surface of the source satisfies the expression q(ξ)=(Bξ2)nexp(−Bξ2), the radiation field, which may be expressed analytically, will maintain approximately the volcano profile in the near field. By employing the theory of the electric field and controlling the shape of the back electrode, a volcano-profiled distribution of the normal component of the electric field and accordingly a same-shaped distribution of the vibration velocity are achieved on the surface of the transducer. In order to improve the radiation efficiency of the transducer, the same material (ceramics) as that of the piezoelectric component, however, unpolarized, is chosen for the back electrode. A once-shaping technique is utilized to make the special-shaped back electrode. The test of the ultrasound field is of satisfying result. The last part of the article gives a brief theoretical description of a nonlinear volcano field. [Work supported by NSF of China.]
Acoustic streaming and temperature elevation in a high viscous fluid by irradiation of ultrasound beams
Authors: Kamakura Tomoo , Huang Hai-Ying , Matsuda Kazuhisa
Published: July 2002

Sound energy losses due to viscosity and heat conduction in a fluid cause the medium movement as acoustic streaming and cause temperature elevation in beams. In most fluids, the buoyancy force by heat expansion is generally weaker than the driving force of the streaming, so the temperature field is basically determined by the heat transfer equation with convective terms. As some physical parameters such as viscosity depend generally on temperature, the sound field is changed with the irradiation time of cw beams. In addition to the viscosity, two other parameters of sound absorption and sound speed are taken account of their temperature dependency in the present theory. The hydrodynamic flow, forced convection heat transfer, and wave equations are simultaneously solved for axisymmetric ultrasound beams by a finite difference scheme. Numerical examples of the streaming velocity and temperature rise are given. They demonstrate that sound pressure amplitude is intrinsically changed with time and sound self-action is generated. The present method of numerical calculation is easily extended to the problems of focusing and multi-layered beam systems.
Inversion of velocity statistical parameters from travel time measurements
Authors: Iooss Bertrand
Published: July 2002

Velocity estimation remains one of the main problems of seismic exploration works. Below a certain range of velocity heterogeneities, deterministic methods become impracticable and the small-scale fluctuations of the velocity field can be described as a random field defined by its first and second statistical moments. It reduces the problem to the determination of a few unknowns, like the mean value, the correlation lengths in the various directions of space, the standard deviation, and the type of correlation function. Theoretical formulas link the statistical moments of an anisotropic random velocity field and those of the travel times of an acoustic plane or spherical wave [A. Ishimaru, ‘‘Wave propagation and scattering in random media’’ (1978)]. They are based on the smooth perturbation method of Rytov and on the parabolic approximation which neglects the heterogeneities with scales smaller than the wavelength. Validity domains of these approximations are studied. Therefore, inversion formulas are derived and inversion procedures of the velocity statistical parameters are developed. Finally, comparisons are made between theoretical predictions and synthetic results performed via finite difference algorithms.
Inverse scattering for porous media with rigid frame
Authors: Depollier Claude , Fellah Zine el Abidine , Aknine Achour
Published: July 2002

The sound propagation in porous materials having a rigid frame filled by air is well described by the equivalent fluid model. In this framework, the interactions between fluid and structure are taken into account in two response factors, the dynamic tortuosity α(ω) and the dynamic compressibility β(ω) defined by the equations
Modelization of Kirchhoff scattering by a sound ray algorithm
Authors: Embrechts Jean J.
Published: July 2002

The problem of the modelization of sound scattering by rough surfaces arises in room acoustics computer simulations, when sound diffusion is taken into account, as well as in other acoustical fields of interest. It is shown here how a sound ray algorithm can be applied to simulate a scattering process obeying the Kirchhoff tangent plane approximation. The Kirchhoff formulation for a random rough surface is briefly recalled, with the shadowing function proposed by Bass and Fuks. The scattered intensity is directly proportional to the statistical distribution of the surface slopes, which here is kept as general as possible. Then, it is established that this formulation is strictly equivalent to the result of a suitable sound ray algorithm, when the wavelength approaches zero in the Kirchhoff formulation. This is demonstrated in theory, and then applied to several Gaussian rough surfaces. Moreover, hints are given to extend the mathematical analysis of the sound ray technique to the second-order reflections on the rough surface. This is viewed as a way to take into account multiple scattering, which is neglected by the Kirchhoff approximation. [Work supported by FNRS, Natl. Fund for Scientific Research.]
Speech research from acoustic transmission to gestural analysis
Authors: Harris Katherine S.
Published: July 2002

My training was in experimental psychology at Harvard, where the focus of the department’s speech work was the characteristics of sounds affecting their error-free transmission, essentially an extension of the Bell Telephone Laboratories’ approach to telephone communication. At Haskins, I began research on the fricative sounds, and discovered the important role of the dynamic characteristics of the sounds in distinguishing among them. In turn, this focus led to an interest in the role of formant movement in speech perception, and ultimately to a study of the characteristics of speech movements themselves. Over the last 50-year period, thanks to some of those on this panel, we have developed a good understanding of the static characteristics of the vocal tract as a producer of speech sounds and the acoustics of speech. However, we still have but a rudimentary account of how the moving articulators develop a dynamic output, and how segmental and suprasegmental transformations of the phonetic message affect this output. Recent instrumental advances should allow the development of an understanding of the dynamics of articulation that parallels our understanding of speech acoustics.
Communication between minds: The ultimate goal of speech communication and the target of research for the next half-century
Authors: Fujisaki Hiroya
Published: July 2002

Needless to say, speech is a manifestation of the information intended by the speaker and is perceived by the listener who tries to retrieve it. Elucidation of the entire process of speech communication thus requires a multidisciplinary approach, as was eminently illustrated by the work of Chiba and Kajiyama about a half-century ago [The Vowel, Its Nature and Structure, Tokyo-Kaiseikan (1941)]. Through the efforts of distinguished researchers, supported by the rapid progress in electronics and computers as well as in other means, the ensuing half-century has seen remarkable advances in our understanding of the linguistic, physiological, articulatory, acoustic, sensory, and cognitive processes in normal, developmental, and pathological cases, as well as in technologies for its utilization. As a new millenium of man–machine symbiosis is entered into, however, still deeper understanding becomes necessary in order to establish a friendly human–machine interface through spoken language, often in multimodal and multilingual environments. In the author’s view, this can only be achieved by investigating and modeling the mind itself as the ultimate source and destination of information. To that end, speech science will need closer cooperation with related disciplines such as brain science, cognitive science, and artificial intelligence.
Language and speech
Authors: Fromkin Victoria
Published: July 2002

It is exciting to note that I have been involved for thirty-six of these important fifty years of phonetic research. In 1962 I entered my first class in Phonetics and Phonology taught by the newly arrived Peter Ladefoged from Edinburgh. That course, and Peter himself, set my goals which have lasted all these years—the relationship between the cognitive knowledge that lay behind our ability to speak and understand. The field of phonetics is varied and researchers have their own agenda and questions to answer. While one’s goals may be practical or theoretical, the answers we all find help us understand the incredibly unique ability of the human animal to communicate in a special, linguistic way. Whether studying normal or abnormal speech (speech errors and aphasia), child language, or language decay, we gain insights into the complexities of the process. In recent years, due to new technological tools such as CAT, MRI, fMRI, PET, ERPs, etc., we have the chance to ask new questions. But still it takes an understanding of the linguistic systems underlying the ‘‘speech chain’’ to know what questions to ask. Linguists therefore are now, as they have always been, important in the research into speech communication.
Immersive audio for desktop systems
Authors: Kyriakakis Chris , Holman Tomlinson , Neven Hartmut , von der Malsburg Christoph
Published: July 2002

Numerous applications are envisioned for integrated media workstations to create, edit, and accurately monitor digital video and audio. There are two major classes of limitations that impede the performance of current desktop loudspeaker-based sound systems. The first encompasses problems that arise due to the local acoustical environment, such as early reflections from the CRT and nearby flat surfaces, as well as the design characteristics and performance of the loudspeakers. The second class involves limitations that arise from variations in human listening characteristics and listener movement relative to the loudspeakers. In this paper several findings are presented that are based on acoustical, psychoacoustical, and signal processing methods for delivering accurate sound field representations. Furthermore, a novel vision-based method for accurate listener tracking is presented that eliminates the need for headgear or tethered magnetic devices. Current findings show that this algorithm can be implemented without imposing a significant computational overhead to the host processor. Research directions include adaptive real-time HRTF synthesis based on the tracking information, as well as vision-based pinna shape classification for improved performance.
The measurement of coloration in electroacoustic enhancement systems
Authors: Poletti Mark
Published: July 2002

The use of electroacoustic systems to enhance the acoustics of concert halls is becoming increasingly prevalent. Regenerative systems are often used for obtaining a source position independent enhancement of reverberation time. However, these systems can produce unnatural acoustics due to the unequal enhancement of the response at different frequencies, a phenomenon termed coloration. Coloration alters the natural Rayleigh statistics of the transfer function magnitudes, and the variation in statistics can be used as a method for quantifying it. This approach avoids the difficulties of examining only the peaks in the transfer function magnitude. A method is developed for measuring the deviation of room transfer functions from Rayleigh statistics. Variance measures are derived. The underlying probability density function is modeled by fitting a three-parameter density termed the generalized gamma function. The maximum deviation of the modeled cumulative distribution from the Rayleigh distribution provides an alternative measure of coloration. The sensitivity of the measures is improved by eliminating the dominant early part of the impulse response, which is largely unaffected by non-in-line systems. An assisted reverberation system simulator is used to simulate the VRA system, which includes a unitary multichannel reverberator in the feedback loop to provide room volume expansion. The simulations show that the coloration measures increase with loop gain as expected, and are independent of other parameters in the system such as the secondary room reverberation time.
Acoustic design and performance of the Bruce Mason Theatre
Authors: Valentine Joanne M.
Published: July 2002

The Bruce Mason Theatre takes an innovative approach to variable acoustics with the use of a variable volume operable ceiling. The overall acoustic design objective was to achieve excellent acoustics with a high level of reverberance for symphony, and good speech clarity with a reduced level of reverberance for theater and drama. The results of commissioning measurements carried out in the auditorium show that a high degree of variability between the acoustic conditions for symphony mode and theater mode has been achieved, and that the operable ceiling/variable volume concept has proved to be highly successful. This paper presents the design concept developed for the auditorium, the findings of a 1:25 scale acoustic model study, and the results of commissioning measurements carried out in the newly opened theater in September 1996.
Extracorporeal shock waves act by shock wave–gas bubble interaction
Authors: Delius M. , Eisenmenger W.
Published: July 2002

Previous animal experimental data had suggested that extracorporeal shock waves acted by the interaction of shock waves with remnant gas bubbles left from cavitational activity of previous shocks. In vitro experiments had shown that haemolysis from shock waves were reduced by >95% by static express pressures from only 1–4×105 kPa in the exposure vessel. This was interpreted as evidence for a reduced shock wave−gas bubble interaction by compression of the remnant gas bubbles by the excess pressure. Additional experiments have shown that haemolysis was lower at 0.2−1×105 kPa excess pressure when the same number of shock waves was administered more slowly. Application of a single strong shock to red blood cells had little effect on haemolysis yet application of two shocks caused an increase of haemolysis by 500%. Static excess pressure abolished the increase. The only interpretation one can think of is that the first shock had caused remnant gas bubbles which acted strongly at the second shock. The term shock-wave gas-bubble interaction is well known from cavitation physics and should be used more often to describe the mechanism of action of extracorporeal shock waves.
Effects of tissue constraining on shock wave-induced bubble oscillation in vivo
Authors: Zhong Pei
Published: July 2002

Using a focused hydrophone (1 MHz), acoustic emission (AE) associated with the rapid oscillaton of cavitation bubbles induced by lithotripter shock waves was measured in kidney pelvis and renal parenchyma of a swine model, and compared with the AE produced in water under the same lithotripsy conditions. At each lithotripter output setting (between 16 and 24 kV), the duration of the primary bubble expansion/collapse was found to decrease as the AE was measured from water to kidney pelvis and renal parenchyma, respectively. As the number of shock waves delivered increased, the ratio of the primary bubble expansion/collapse to the subsequent ringing time was found to be almost unchanged in water, but varied significantly in both pelvis and renal parenchyma. These findings indicate a tissue-constraining effect on lithotripter shock wave-induced bubble oscillation in vivo. [Work supported by NIH.]
Wideband laser-acoustic spectroscopy of proteins
Authors: Karabutov Alexander A. , Podymova Natalia B.
Published: July 2002

The absorption of ultrasound in a frequency range of 2–50 MHz in proteins was investigated with a wideband laser-ultrasonic spectrometer. It was found that for fresh chicken proteins ultrasonic absorption is proportional to the squared frequency. Denaturation of proteins transforms the spectrum of ultrasonic absorption to the first power of frequency dependence. In the hole frequency range the ultrasonic absorption in denaturated protein is higher than in the fresh one. The possibility of laser ultrasonic diagnostics of proteins is discussed.
Finite-element simulation of piezoelectric transformers
Authors: Tsuchiya Takao , Kagawa Yukio , Okamura Hiroki
Published: July 2002

A three-dimensional finite-element approach to the characteristic prediction of piezoelectric transformers is presented. For a numerical example, a Rosen-type piezoelectric transformer is considered. The electrical input admittance and the transmission or transfer characteristics are demonstrated for the fundamental longitudinal mode operation. Based on these characteristics, the lumped parameters are extracted to form the electrical equivalent circuit. The effect of the loading or termination condition on the output voltage and the conversion efficiency are also examined. The numerical results are then compared with the experimental results. Examination is then extended to the optimum design in terms of efficiency and the output voltage.
Specific acoustic impedance of the ultrasonic field by the square flat transducers
Authors: Imamura Tohru
Published: July 2002

Sound pressure, particle velocity, and specific acoustic impedance are investigated, using the case where square flat transducers are tilted from a parallel condition. Specific acoustic impedance is a quotient of sound pressure by particle velocity. Particle velocity is computed by numerical quadruple integration with Huygens’s principle, and compared with that of the plane wave. The ratio of the half side length (a) of the square flat transducer to the wavelength (λ) of the ultrasonic wave is set at 2.5, and the distance between the transducers is set at 5a or 10a. The feature of the phase delay leap of the specific acoustic impedance on the central axis of the circular flat transducer does not appear for the square case.
Dynamic optimal tuning of electronic keyboards as they are being played
Authors: Steck James E. , Roush Dean K.
Published: July 2002

The 12-tone equally tempered musical scale can produce noticeably imperfect matching of acoustic harmonics when some combinations of tones are played together. The lower partials (harmonics) which should match, do not. For a 12-tone octave, if a small number of tones in the octave are to be sounded simultaneously, a tuning can be found which produces harmonic errors that are much less than that of equal temperament. Historically, these tunings have been discovered, explored, and abandoned in favor of equal temperament because they generally have much worse harmonic error for tone combinations other than those for which the tuning was optimized. Here, a mathematical description of the total harmonic error of a musical instrument is presented along with a mathematical method which solves for a tuning (tone frequencies) that minimize this total error. The optimal tuning calculations have been implemented in ‘‘C’’ code on a 166-MHZ pentium desktop personal computer equipped with a Creative Labs Sound Blaster AWE 32 soundcard, with a MIDI keyboard attached. The ‘‘C’’ code reads the keys (tones) being played on the keyboard, calculates the optimal tuning, and sounds the tones on the PC soundcard at the optimally tuned fundamental frequencies.
Subjective response to aircraft flyover noise
Authors: Brown Sherilyn A. , Hilliard R. David
Published: July 2002

In order to obtain increased understanding of community response to aircraft noise, a comprehensive subjective study was designed and implemented to realistically simulate the aircraft noise exposure experienced by residents living both near and far from airports. The test was designed to present a wide range of daily aircraft noise exposures ranging broadly in both quantity and amplitude. The In-Home study was supported by a computer controlled sound playback system which exposed test subjects to aircraft sounds during a daily 14 h test period. This system provided a degree of control over the noise exposure not found in community situations and a degree of situational realism not available in the laboratory. Each day the system played from 0 to 448 flyovers as the test subject went about his or her normal activities. At the end of the day, the test subjects rated their annoyance to the flyovers they had heard. The noise exposures presented during 9 weeks simulated different combinations of runway activity, aircraft flyover altitude, rush hour conditions, and occasional loud aircraft among many low sound level flights. Subsequent data analysis will seek to provide a basis of understanding of annoyance response to enhance predictive algorithms for a wide range of aircraft noise exposure conditions.
The acoustic and sound design for a museum exhibition on indigenous music and dance
Authors: Coulter Peter G.
Published: July 2002

Museum exhibitions commonly use visual design to orientate and inform the visitor. At the Powerhouse museum in Sydney, Australia, an exhibition (entitiled Ngaramang Bayumi) was recently developed on indigenous music and dance. This exhibition was designed to orient the visitor using aural cues, in addition to the visual. This has been achieved by the use of acoustic design and through the use of a specialized sound systems that presents a 3-D sound (ambisonics), that calls and guides the visitor through the space. The experience, along with audiovisuals, objects, text, and graphics uses unusual geometries, layouts, and building materials. Using this design as a case study, this presentation will explain the research and development of the acoustic elements within the exhibition. These are the elements of cross talk, sound quality, sound focusing, sound isolation, sound ambience, localization, dynamic range, and reverberation times. Visitor reaction to the exhibition will also be discused.
Measurement of ultrasonic displacement vector with an F-P interferometer
Authors: Qian Menglu , Pan Yongdong , Zhang Zhongxian
Published: July 2002

The laser interferometer technique for receiving ultrasound has potential for a wide range of noncontact ultrasonic measurements and has therefore received considerable interest in recent years. Several interferometric methods for detecting the normal displacement components of ultrasound have been developed and applied to nondestructive evaluation for material characterization. In order to study the propagation of ultrasound in a medium and to characterize materials more accurately, detecting both normal and tangent components of ultrasonic displacement simultaneously is necessary. Therefore, an F-P interferometer, which receives scattering lights at scattering angles +θ and −θ from sample surfaces and measures the ultrasonic displacement vector simultaneously, is introduced in this paper. In order to increase the scattering light intensity and determine the scattering angle θ precisely, a new method for modification of a sample surface is introduced and some experiments are presented in this paper.
Two-frequency degeneracy of an acousto-optic interaction in paratellurite
Authors: Yurchenko Alexander , Moskalev Vladimir
Published: July 2002

Earlier unknown effects of an acousto-optic interaction degeneracy in paratellurite have been studied. Its essence compared to described phenomena lies in the fact that a light beam can be diffracted twice by acoustic waves with different frequencies instead of being typically diffracted twice by the same acoustic wave. It happens due to strong acoustic anisotropy of paratellurite. Bragg conditions resulting in the degeneracy can be satisfied under a certain frequency correlation of two acoustic slow shear waves. A light beam diffracted by one spectral component of a complex acoustic signal can be effectively diffracted again by another spectral component. Thus, a physical mechanism of this effect is the same as it is in the ordinary case but it is observed under different conditions (different frequencies). Necessary calculations of such interactions have been carried out. The frequency of the ‘‘unfavorable’’ spectral component was calculated depending on the frequency of the ‘‘useful’’ one for the case of nonaxial acousto-optic interaction in paratellurite. The found effect was shown to take place and to be important for real acousto-optic devices. In the studied case, the frequencies of acoustic waves interacting with a light beam were equal to 44.7 and 43.2 MHz, respectively.
Photoacoustic signal in the system of a thin oil layer on the water surface
Authors: Sliwinski Antoni , Pogorzelski Stanislaw , Szurkowski Janusz
Published: July 2002

Thin layers of different kinds of oils spread on the water surface (using standard techniques) were examined by photoacoustic spectroscopy (PAS) methods. Both techniques of excitation were applied: the classic one with a modulated light beam as well as with a laser pulse beam. It was demonstrated that the mechanism of molecular interaction at the oil–water interface represents a good model for determination of the correlation between PAS signal characteristics (amplitude and phase) and physico-chemical properties of the thin layer system. The results obtained have confirmed the existence of a very sharp separation of the oil and water phases. Variations in physical properties of layers of different thickness like surface and interface tension thermal conductivity and heat capacity and optical absorption coefficients influenced by different agents (e.g., surfactants) could be detected with the PAS methods applied. [Work supported by KBN.]
Monotic and dichotic musical-interval identification in listeners with cochlear-based hearing loss
Authors: Arehart Kathryn H. , Burns Edward M.
Published: July 2002

This study examined musical-interval identification in musically experienced listeners with cochlear-based hearing loss. Sounds had missing fundamentals ranging from 100–500 Hz. These missing fundamentals were conveyed by two successive harmonics presented either to the same ear or to separate ears. Performance was measured as a function of the average rank of the lowest harmonic for both monotic and dichotic conditions at both 20 dB sensation level (SL) and 30 dB SL. In both monotic and dichotic conditions, listeners with cochlear-based hearing loss demonstrated excellent musical-interval identification at low fundamental frequencies and low average ranks, but abnormally poor recognition at higher fundamental frequencies and higher average ranks. The results will be related to auditory deficits which might affect complex-tone pitch perception in listeners with cochlear-based hearing loss, and will be discussed in the context of modern pitch theories. [Work supported by Deafness Research Foundation.]
A design of a tactile voice coder with different tactile sensations for the hearing impaired
Authors: Wada Chikamune , Ino Shuichi , Shoji Hisakazu , Ifukube Tohru
Published: July 2002

A tactile voice coder is a device which changes a speech sound into a vibratory pattern and presents it to the tactile sense of the hearing impaired. The authors have been improving the tactile voice coder in order that the hearing impaired can identify consonants easier. The use of a convex stimuli pattern, similar to Braille, in addition to the vibratory stimuli is proposed, as one of the ways of improving the tactile voice coder. The authors have made this proposal based on the hypotheses that the combination of the vibratory stimuli and the convex stimuli could transmit more speech information. From the combination of basic experiments, the authors have found that presenting a vowel using the convex stimuli and a consonant using the vibratory stimuli was better than only using the vibratory stimuli. Therefore, based on our findings, the authors have designed a new tactile voice coder which uses a different tactile sensation.