bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical study of a one-dimensional resonant gas oscillation in a closed tube
Authors: Yano Takeru
Published: July 2002

The one-dimensional resonant gas oscillation in a closed tube is numerically studied by solving Navier–Stokes equations of gasdynamics. Accurate numerical solutions are obtained by using an eighth-order Padé type compact finite-difference scheme without any artificial viscosity and the second-order Runge–Kutta method. The solutions show that a shock wave of sufficiently steep front is formed even in the case of M=O(10−5), where M is the acoustic Mach number at the sound source located at one end of the tube. The evolution process from the initial state of uniform and at rest to a quasisteady state including a shock wave is analyzed. The result is compared with earlier works based on the first-order weakly nonlinear theory.
Pitch mechanisms for unresolved harmonics II: Sensitivity to envelope phase
Authors: Plack Christopher J. , White Louise J.
Published: July 2002

Introducing a phase change between two short bursts of a sinusoid can produce a pitch shift which corresponds to a shift in the peak of the long-term spectrum [I. V. Nabalek, Acustica 82, 531–539 (1996)]. The present experiment examined whether a similar effect could be obtained for a complex tone consisting of unresolved harmonics where the phase change was applied to the envelope of the complex. For unresolved harmonics a pitch is heard corresponding to the fundamental frequency (F0) of the complex even though the F0 component is not physically present. It is likely that F0 is extracted from neural phase locking that provides a crude representation of the envelope of the complex (which repeats at F0). The complex consisted of the harmonics of a 250-Hz F0 filtered between 5500 and 7500 Hz. A phase advance of 0.75 F0 periods between two 20-ms bursts produced a downward pitch shift of almost 10 Hz when the bursts were contiguous but no downward shift when the bursts were separated by a gap of 5 ms or more. The results are consistent with a long-term pitch mechanism sensitive to envelope phase that can be reset in response to discontinuities in the stimulus.
The role of global processes in the perceptual cohesion of harmonic complex tones
Authors: Brunstrom Jeffrey M. , Roberts Brian
Published: July 2002

Harmonic components typically fuse to form a single perceptual entity. Their spectral positions are consistent both globally, because of the regular pattern defined by the other components, and locally, because of their equidistance from adjacent components. This study explored the contribution of global regularity to harmonic fusion. On each trial, subjects heard a periodic complex tone, derived from a 14-harmonic complex, followed by an adjustable pure tone in a continuous loop. Either two, three, or four consecutive components (harmonics six and above) were removed from the original complex and replaced by a ‘‘probe’’ component, located at one of a set of regularly spaced positions spanning the gap created in the complex. Subjects were instructed to match the pitch of the pure tone to that of the probe. Generally, they were successful unless the probe coincided with a harmonic position in the complex, though to a lesser extent, this was true even when the probe matched a nonconsecutive harmonic position. This indicates that the cohesion established by a set of harmonics is not dependent upon spectral equidistance between adjacent components. Rather, the effects of this kind of spectral pattern can extend into a multicomponent gap in a harmonic series.
Trading level for number in the laboratory: Differential effects of aircraft noise on cardiovascular activation, annoyance, and assessment of quality of life
Authors: Mauss Iris B. , Vogt Joachim , Kalveram Karl Th.
Published: July 2002

As aircraft become quieter, the question arises to what extent the decrease in noise is convertable into an increase in the number of flight movements without enhancing psychological and physiological noise effects. Conventional reasoning has it that it suffices to keep constant the energy equivalent noise level. In a 3×3 design combining three number conditions (3/9/27 overflights during 30 min) with three noise level conditions (aircraft types emitting 71/76/81 dB(A) per overflight), this assumption was tested, using three groups of 12 subjects each for the number conditions, and repeated measurements for the level conditions. Comparisons between the equal-energy conditions (e.g., 3×76 dB vs 9×71 dB) did not show any significant differences regarding systolic and diastolic blood pressure and heart rate. Regarding ratings for annoyance in the lab situation, results were the same with a slight tendency for underenergetic number effects, that means, more but softer aircraft were preferred. However, if the subjects imagined to reside in a region continuously exposed to the experienced noise, quality of living was assessed as slightly more negative for residential areas with nine overflights, and clearly more negative for 27 overflights, though energy was fixed. This suggests overenergetic number effects for living quality beginning at about 18 overflights/h.
Statistical data of excess attenuation for long-range noise propagation over sea
Authors: Konishi Kazuo , Maekawa Zyun-iti
Published: July 2002

At an environmental impact assessment of a new planned airport on an artificial island, many data of excess attenuation were obtained in long-range (5-km) sound propagation over sea continuously for 14 months versus meteorological conditions. Unfortunately, as presented at Inter-Noise 96 and 97, clear relations were not found between them using both multiregression analysis and multidimensional quantification analyses. Although it is known that the sound-speed profile is one of the most effective factors in long-range sound propagation, it seemed to be difficult to obtain the profile sufficient to predict the sound propagation over sea. Furthermore, it is very difficult to predict the excess attenuation, possibly because of the existence of unpredictable turbulence in the atmosphere. Therefore, using the measured data, attempts were made to estimate the excess attenuation related to aircraft noise at a receiving point. After statistical analysis, it has become clear that the excess attenuation is almost positive, and negative only at night. This fact is very useful for the environmental impact assessment of the planned airport.
Sound propagation in a city composed with hexagonal periodic buildings
Authors: Picaut Judicael , Hardy Jean
Published: July 2002

The noise propagation in central parts of towns is a problem of major importance. Because of multiple reflections upon the buildings the background noise obeys to a diffusion law in place of a free propagation law. Usually the diffusion law is obtained by means of a random disposition of the buildings. The originality of this work is to show that this hypothesis can be avoided since the example given is composed with hexagonal periodic buildings, with a semidiffusing law for the reflections. A hexagonal geometry is used, cumulating the advantages of simplicity for the refections laws and avoiding the avenue effects. A numerical simulation shows that a diffusion occurs for the rays and the dependence of the diffusion coefficient from the geometrical dimensions of the streets, the complexity of the building façades is investigated. The model suggests that for a realistic case two parameters suffice to describe the noise propagation in a town: the diffusion coefficient depending of the complexity of the façades and the streets width and an attenuation coefficient depending of the sizes of buildings and of the attenuation properties of the reflecting surfaces and of the air.
Steady streaming from a noncompact sphere
Authors: Gopinath Ashok , Trinh Eugene H.
Published: July 2002

An analytical study has been conducted of acoustic streaming around a rigid sphere in a plane standing acoustic field under the noncompact sphere approximation. Under these conditions the sphere size is allowed to be comparable to the (radian) wavelength of the acoustic field, thus making the usually ignored compressibility effects significant in the flow. However, the amplitude of fluid oscillations is assumed small compared to the sphere size, and their ratio serves as the appropriate perturbation parameter in the matched asymptotic technique being used. The solution calls for a Helmholtz type decomposition of the velocity field into the sum of the gradient of a potential function, and the curl of a suitably vectorized stream function. The role of the nonlinear interactions of both the potential function and the stream function is pointed out, and the resulting streaming flow patterns are contrasted with those obtained in the incompressible case. This work would find application in determining transport rates in containerless processing using acoustic levitation with ultrasonic frequencies. [Work supported by NASA.]
Entertainment park noise control devices
Authors: Cocchi Alessandro , Semprini Giovanni
Published: July 2002

A big entertainment park is operating with noisy attractions near the Garda lake, a pleasant land where people go not only for amusement but also to relax, especially during holiday time. Noise measurements have been made during different periods of daytime and a noise map has been developed taking into account the difference of level between the top of the noisiest attraction and the windows of the most exposed house. Starting from this computerized model, and knowing the emission spectrum of the most relevant sources, it has been possible to design some noise control device useful for reducing the noise exposure level restricted to the exposed houses alone: This was possible combining earth barriers and a hot windstream.
Propagation of vibration waves in a pipe
Authors: Simion Mihail-Dan F. P. , Simion Gabriela-Cristina D. , Simion Florian-Paul
Published: July 2002

Our studies concerning propagation of vibrations inside a pipe presume a behavior analysis for a continuous medium, but also a dynamic study of elastic medium. A diagram for describing the behavior of a viscoelastic medium is represented with emphasizing properties of material. In our case energy is transmitted through propagation of longitudinal pressure waves. Every particle of medium is vibrating around its equilibrium position. The relation for deformations dependence on tensions are determined, taking into account a medium with negligible viscosity. Propagation velocity for longitudinal and transversal plane waves are computed, by aiding Navier equations. A ratio between longitudinal waves propagation velocity and transversal waves propagation velocity equal to 1.87 for v=0.3 is obtained.
Thermoacoustic refrigeration demonstration
Authors: Wakeland Ray Scott , Garrett Steven L.
Published: July 2002

A portable device for demonstrating thermoacoustic cooling is developed using off-the-shelf components: the Morel MW-142 5-in. woofer and the Selenium HL14-25 horn. Acoustic peak pressure amplitudes of 19 kPa (19% of mean pressure) have been measured (without stack) using atmospheric air as the working fluid. Measurements of spectra, quality factors, stack temperature differences, and heat pumping capacity are compared to DeltaE models. Use of off-the-shelf components leads to design considerations not encountered in full-scale devices. For example, the high mechanical resistance of the driver, which was intended for audio reproduction, dictates against making the driver coresonant with the resonator, as is common when the driver is designed for operation at a specific frequency. [Work supported by NSF and ONR.]
Theory of nonlinear acoustic waves in a thermoacoustic prime-mover
Authors: Lotton Pierrick , Gusev Vitalyi , Bailliet Hélène , Bruneau Michel
Published: July 2002

An equation describing stabilization of oscillations in a thermoacoustic prime-mover was derived: ∂V/∂t−V(∂V/∂τ)+(A−D)(∂V/∂τ)=√2/πA∫−∞τ(∂V/∂τ′)[dτ′/(τ−τ′)]+V+D(ℒ3V/∂τ3). In this equation, particles velocity V, ‘‘slow’’ time t, and ‘‘fast’’ time τ are normalized; parameters A and D depend on temperature distribution inside thermoacoustic stack. The third term on the left-hand side (lhs) describes a shift in resonance frequency of a half-wavelength resonator caused by a stack installation. The third term on the right-hand side (rhs) describes sound velocity dispersion when the stack is acoustically thin. The first term (if A>0) and the second term on the rhs describe sound amplification due to quasiadiabatic interaction of acoustic and thermal waves. The first term on the rhs contributes also to dispersion. Particular analytical solutions were found and computer modeling was applied for the analysis. Conditions when a shock front formation caused by acoustic nonlinearity (the second term on the lhs) is the dominant mechanism for the saturation of wave amplitude were determined. [Work supported by DGA.]
Comodulation masking release with tone pips added out of phase to the valleys of a sinusoidally amplitude modulated pure tone
Authors: Fantini Deborah A. , Delahaye Roel , Meddis Ray
Published: July 2002

Two studies of comodulation masking release (CMR) investigated the influence of temporal position of brief signals added to a modulated on-frequency band (OFB) [Grose and Hall III, J. Acoust. Soc. Am. 85, 1276–1284 (1989); Moore et al., ibid. 87, 1683–1694 (1990)]. The former reports mixed results as to whether flanking bands (FBs) modulated to the same depth as the OFB elicit more CMR than 100%-modulated FBs. The latter reports that when antiphase signals are added to valleys of 50%-modulated OFBs, thresholds with correlated FBs are poorer than with quadrature-phase FBs. In the present paper, signals were three antiphase tone pips added to valleys of a 50%-modulated 700-Hz pure tone. Thresholds were obtained with the OFB and 6 FBs, modulated at 10 Hz. FBs were comodulated or in quadrature phase with the OFB, at either 50% or 100% depth. With 50% FBs, subjects performed better with comodulated than with quadrature-phase FBs. With 100% FBs, performance in the comodulated condition improved, and in the quadrature-phase condition was impaired, relative to 50% FBs. These results indicate that CMR can occur when antiphase signals are added to valleys of 50%-modulated OFBs.
A model of auditory image flow. I. Architecture
Authors: McAngus Todd Neil P.
Published: July 2002

A model is presented here based on the theory that the auditory cortex computes the spatio-temporal power spectrum of the auditory image flow [D. Heeger, ‘‘Model for the extraction of image flow,’’ J. Opt. Soc. Am. 4, 1450–1470 (1987)]. A computational implementation of the model has the following components: (1) a gammatone filter-bank spaced on the ERB rate scale; (2) an orthogonal, ERB spaced modulation filter-bank which generates a 2-D modulation map which is then low-pass filtered; and (3) a population of causal 3-D spatio-temporal Gabor filters which compute the spatio-temporal power spectrum of the image sequence. The cortical filters are organized into families such that each member of the family occupies the same spatial-frequency band but has a different spatio-temporal orientation. The spatial frequencies range from 0.05 cycles erb−1 to 0.4 cycles erb−1. The temporal frequencies range from ±0.5 to ±64 Hz. The spatio-temporal power spectrum may be visualized by replacing each image pixel with the output of all filters centered at the pixel arranged in frequency and orientation bands, somewhat like orientation columns in the visual cortex. This model may be applied to modulation perception and auditory grouping.
Nonlinear effects in a vibrating string (wire)
Authors: Hanson Roger J. , Macomber H. Kent , Kassakatis Michael P.
Published: July 2002

Many unusual effects are observed in vibrating strings or wires as a consequence of tensional changes and longitudinal motion which yield coupled nonlinear equations for transverse motion in orthogonal directions. For a wire driven sinusoidally in a transverse direction, notable effects observed at driving frequencies near a natural resonance include the generation of motion perpendicular to the plane of the driving force, sudden jumps in amplitude and phase, whirling motion, and hysteresis [R. J. Hanson, J. M. Anderson, and H. K. Macomber, J. Acoust. Soc. Am. 96, 1549–1556 (1994)]. Further work demonstrates the generation of second, third, and higher harmonics with amplitudes sometimes comparable to the first. These harmonics, present in both the driving and perpendicular directions, contribute to a very complex total motion. All of the effects are very sensitive to asymmetries which produce slight differences in free vibration frequencies in two orthogonal directions. For the large amplitude free vibration of a plucked string, there are also significant consequences of the nonlinear effect of the tension changes. These effects for a plucked string will be related to several musical instruments. Phenomena for both the driven and plucked cases will be qualitatively demonstrated with video displays of the signals from optical motion detectors.
Loudness of combined noises derived from singular and concurrent community noises
Authors: Berglund Birgitta , Nilsson Mats E.
Published: July 2002

It seems logical to assume that the total loudness of combined noises should correspond to the arithmetic sum of the loudnesses of the singular noises as perceived within the combined noise. Although postulated by Powell in the mid 1970s, this hypothesis has not yet been empirically tested. In real life situations, a particular community noise is always perceived within a complex of environmental noises, and therefore, both its loudness and the annoyance it evokes will be associated with the noise immission rather than the noise emission from the singular source. Binary combinations of community noises were tested at up to seven levels of loudness and subjects estimated the loudness of combinations as well as the singular sounds with the aid of magnitude estimation. The loudness summation did not follow Powells arithmetic summation hypothesis. The loudness of singular noises differs when heard alone compared to when heard within the noise combination. As a consequence the type of interaction between loudness of community noises in real life situations (heard within) clearly has implications for the development of better models for total loudness as well as for total annoyance. Earlier models hvae relied on data produced from singular noise sources when heard alone.
Annoyance accumulation modeling in a community noise annoyance expert system
Authors: Botteldooren Dick
Published: July 2002

When the state of the sound environment in a region is monitored by tracing the percentage of people who are annoyed by noise, simulation models for community noise annoyance are needed. They allow, for example, the prediction of the impact of various noise control measures. Building such simulation tools is not an easy task because information is scarce and relations between quantities involved are uncertain. Therefore, an expert system was built that makes optimal use of the scarce information and combines as many expert opinions as possible. Consensus mechanisms, representation of uncertain data, and model uncertainty are key factors in this model. Combination of annoyance caused by different sources is an important part of the system. Models proposed by various scientists are combined and compared to obtain the most likely global annoyance percentage. Both psychophysical and perceptual models can be applied at the same time. The probability approximation that is used for this task will be introduced. The results of this approach, which combines different opinions, will be shown for a number of example situations.
On the asymmetric waveform of shock waves in high-amplitude focused sound fields
Authors: Hobaek Halvor
Published: July 2002

The asymmetric shape of shock waves generated in high-amplitude sound fields, where the peak positive pressure tends to be much higher in amplitude than the peak negative pressure, is well known. Numerical simulations based on the KZK equation show excellent agreement with experimental observations of the field from a focusing circular sound source with a pronounced asymmetry. This equation accounts for diffraction, absorption, and nonlinear effects. Thus the asymmetry must be due to diffraction, because the plane wave limit of the KZK equation (Burgers’ equation), accounting for nonlinearity and absorption only, predicts symmetric waves (if the initial sound is sinusoidal). However, experimental results indicate that the shock front is strongly connected with the contribution from the central part of the source, while diffraction gives rise to the edge wave which propagates independently of the shock, these two signals can easily be distinguished. Spectral analysis of the measured waveforms on the axis show that each harmonic component has an almost constant phase offset (a symmetric N wave has none). The edge wave can have negligible influence on this phase shift. Thus the question is, how does diffraction cause asymmetry? Results on the analysis of this problem will be presented.
Parameter sensitivity in nonlinear and dissipative time-reversed acoustics
Authors: Hedberg Claes M.
Published: July 2002

Time-reversed nonlinear acoustics has shown that a propagated signal retains information about the original signal after shock formation and even after merging of shocks. This information is naturally very dependent on the accuracy of the measured or calculated data. Presented here is a more detailed analysis of the estimation of the dimensionless parameters in the problem: the original amplitude, the distance traveled, and the dissipation over nonlinearity ratio. The robustness of alternative methods and their sensitivity to noise and incomplete data are investigated.
Equal-loudness relations at high frequencies: Implications for loudness growth
Authors: Hellman Rhona , Takeshima Hisashi , Suzuki Yoiti , Ozawa Kenji , Yamaguchi Takanori , Sasaki Yusaku , Sone Toshio
Published: July 2002

Equal-loudness relations spanning a wide range of sensation levels (SL) were measured by the method of adjustment for 12 pairs of frequencies from 1 to 16 kHz. Sensation levels were based on individual thresholds measured prior to the equal-loudness determinations by an adaptive 2IFC procedure. To test for transitivity, three reference frequencies at 1, 3.15, and 5 kHz were used. Below 8 kHz, the matching results were well described by a linear function with a slope of 1.0; at higher frequencies, the functions became increasingly curvilinear. Near threshold and at moderate SLs the loudness of a tone at 12.5 kHz and higher increased more rapidly than the loudness of the lower-frequency reference tone; at high SLs it increased more slowly. The dependence of the slope of the matching function on level was most pronounced at 16 kHz. Moreover, nearly perfect transitivity was observed. The reduction in slope at high SLs is consistent with recent evidence that severely restricting the spread of excitation to high frequencies decreases the tone’s rate of loudness growth [R. P. Hellman, J. Acoust. Soc. Am. 96, 2655–2663 (1994)]. [Work supported by the Japanese Ministry of Education, Science, Sports, and Culture.]
Meridional and helical ray contributions to backscattering by tilted cylindrical shells: High-frequency tone burst and wide bandwidth measurements and interpretation
Authors: Morse Scot F. , Marston Philip L.
Published: July 2002

When viewed in the frequency-angle domain, the backscattering by truncated thick cylindrical shells in water exhibit various ridges of high backscatter. These enhancements are associated with leaky waves excited on the shell and can be described in terms of meridional and helical rays. The enhancements are not present for a rigid scatterer of the same shape and may be important for interpreting high-frequency sonar echoes. Previous work [Morse et al., J. Acoust. Soc. Am. (to be published)] has shown that these enhancements are not limited to near broadside incidence but can extend to end-on incidence in the coincidence frequency region. Results of broadband and tone burst measurements of these enhancements are presented. High-frequency tone bursts may be used to separate the meridional ray enhancement from the generally weaker helical ray enhancement. The general angular width of the meridional ray enhancement may be explained using an approximate ray theory [Marston, J. Acoust. Soc. Am. 102, 358–369 (1997)]. The amplitude of the backscattered meridional ray depends on the leaky wave reflection coefficient at the end of the cylinder which appears to be affected by mode conversion near mode thresholds. [Work sponsored by the Office of Naval Research.]
21st century user interfaces within the telecommunication industry: Speech processing is the key
Authors: Wilpon Jay
Published: July 2002

As we move into the 21st century, several market factors will play a key role in the success of telecommunication-based services. Such factors include: The merging of the computer and telephony industries is moving ahead at an ever-increasing pace. Barriers-to-entry for new companies wishing to enter traditional telephony businesses are dropping. The union of the computer and telephony industries will lead to effective integration of voice, traditional data, and video, enabling the creation of new services that are more robust, intelligent, and accessible than services that are currently available. People will not be asking for technology, they will be asking for a simpler and easier lifestyle. Given these factors, what will differentiate 21st century telecommunications services from each other are innovative, compelling 21st century user interfaces that create a media center unifying emerging desktop services with traditional telephony services. Such user interfaces will lead to smarter services. As networks automatically learn their customers’ needs and wants, and customers invest their time to learn these intelligent user interfaces, a bond will be formed. Key to this vision is the availability of robust large vocabulary speech recognition, spoken language understanding, and text-to-speech synthesis technologies that allow customers to access information and each other anywhere, anytime.
Speech recognition trends and predictions, or, do we need text?
Authors: Price Patti J.
Published: July 2002

Speech is the means of communication used first and foremost by humans. Automatic speech recognition capabilities are still far from those of humans, particularly with respect to degradation in the face of noise, nonnative speakers, and casual speech styles. However, significant advances have been achieved in recent years; automatic speech recognition capabilities now permit us to use speech as an interface for dictation and for information access. In such applications, the interactivity of the system allows the person to adapt to the system (and the system to adapt to the user). The real challenge of the information age is using speech not just as a medium for information access, but as itself a source of information, wherever speech occurs. Examples include: voice annotation for later retrieval, sorting and prioritizing voice messages, access to voice recordings of meetings without the need to take minutes, and access to broadcast media. Speech technologies in support of such applications include not just speech recognition, but also speaker recognition, topic spotting, gisting, and summarization. This talk will survey the state of the art and recent trends in speech as a source of information.
Improvement of pitch detection using a signal specific analyzing wavelet
Authors: Chisaki Yoshifumi , Usagawa Tsuyoshi , Ebata Masanao
Published: July 2002

Many methods of a speech enhancement system in a noisy environment have been studied. A wavelet transform performs better in analyzing speech than a fast Fourier transform at the point of frequency resolution when the purpose is focused on the pitch detection. Analyzing wavelets, such as Gabor, are derived from a mathematical approach, which have characteristics of low, high, and bandpass filters. In this paper, a modified wavelet transform is proposed. A signal which has characteristics of the target signal is applied to an analyzing wavelet. This signal-specific analyzing wavelet includes not only amplitude and phase for each frequency but also the relationship of harmonic components and a periodic fluctuation of pitches. In addition, the wavelet transform is arranged to use a signal-specific analyzing wavelet for tracking pitches. This method is useful not only for the pitch detection but also for the representation of the fluctuation. Experiments are performed by using both a Gabor function and a signal-specific analyzing wavelet changing both vowels and a bandlimited noise. As a result, the ratio of pitch detection was improved by comparing a signal-specific analyzing wavelet with a Gabor wavelet transform. The ratio was recovered over 40% in case of SNR=0 dB.
Acoustics in the competition for the construction of ‘‘La Fenice’’ opera house
Authors: Biggi Maria Ida , Pompoli Roberto
Published: July 2002

In 1789, a group of nobles wished to build a new large theater in Venice. They announced a competition, in which 29 architects from all over Italy took part, presenting many different projects. Although the prize was given to one project, a different one was chosen to be executed. The author of the latter project was Giannantonio Selva and was the cause of much criticism, but it was appreciated for the results it obtained from the acoustic point of view. In his memoirs, Selva explained how he adapted the shape of the theater so that it became a semicircle with extensions on both sides and added that there were no precise theories regarding the building of a ‘‘harmonic’’ theater. He also appeared to be well informed on the debate about different curves to use in the hall. He suggested leaving an empty space under the orchestra pit, because ‘‘it looks good.’’ This paper deals with the description of the acoustical requirements in the competition for the construction of ‘‘La Fenice’’ and with the analysis of some of the projects presented taking into account the knowledge of room acoustics in the XVIII century.
Acoustics of the historical opera house of Bordeaux: Comparison between the results of objective and subjective surveys
Authors: Semidor Catherine , Barlet Aline
Published: July 2002

This paper deals with the relationships between objective and subjective results of an acoustic survey in the historical opera house of Bordeaux. The investigations were conducted with ordinary opera-goers during four performances of ‘‘Traviata’’ in order to have available statistical population answers. The results of an earlier experiment [C. Semidor, Proc. IOA 19, Part 3, 29–38 (1997)] carried out in a dual-purpose hall with a test questionnaire built with simple words which explain the sensations of the listeners, have shown that the questions are correctly understood. The comparison of the ordinary listeners’ answers with the objective results shows that the auditive sensations are fitting with the measured criteria obtained in the opera configuration with the opened pit and sceneries on the stage. For example, for the majority of people asked, the sound in this hall seems clear and coming directly from the stage (no surrounding by the sound sensation), and the sound attack impression is very clear, which is correlated by the weak values of reverberation time and EDT. In spite of comfort defects due to the age of the opera house, such as the lack of space between the seats, the architecture of the Grand Theatre of Bordeaux is very well appreciated.
La Cité de la Musique in Paris
Authors: Commins Daniel E.
Published: July 2002

Fifteen years have been necessary to program, design, and build the Cité de la Musique in Paris. The author has been personally involved in all phases of the project and has assumed the principal acoustical responsibilities, with assistance from many acousticians. This music complex has two parts: the National Conservatory of Music and Dance, with some 250 music rooms, and the concert hall wing. The main concert hall, which has been in service for a few years, has a capacity of 900 to 1200 only, but it is designed in such a way that it can be used for various orchestral configurations: classical, in the round, central, etc. This means, of course, that acoustical reciprocity is a must: hearing conditions and musicality must be adequate for any pairs of points, in spite of the elliptical shape of the concert hall. The present paper will describe the means used to achieve a correct acoustical result in the concert hall and will give some insight into the characteristics of some of the other rooms.
The generation of ambient noise due to breaking surf
Authors: Wilson James H. , Bourke Robert H. , Fabre Josette P.
Published: July 2002

The past predominance for deep-water acoustic studies has dictated that little consideration be placed on the role of the surf zone as a source of ambient noise. Recent emphasis on propagation in coastal waters has increased the awareness of the importance of breaking surf to the noise field in littoral waters. Two recent studies, in Monterey Bay, CA, and at Duck, NC, have provided for the first time information on the source level density of surf-generated ambient noise. Inverse techniques were developed to infer the source level density from the total ambient noise field as measured at several offshore hydrophones. Source level spectra from 50–1000 Hz demonstrate a −5-dB/oct slope with absolute levels varying by 10–15 dB dependent on wave height and distance from the surf zone. Surf noise was found to contribute 80% (95%–99%) of the total offshore ambient noise during light (heavy) surf conditions. The inverse technique is highly dependent on accurate modeling of the transmission loss seaward from the surf zone, being predominantly a function of the geoacoustic properties of the sea bed. Additional comments will address breaker types and factors affecting breaker height and the noise due to waves breaking on the ice edge of the Greenland Sea.
Measurements of the space–time–frequency distribution of the noise in the surf zone
Authors: Heitmeyer Richard M. , Means Steven L. , Wales Stephen C. , Livingston Ellen S. , Schindall Jeffrey A. , Orr Marshall H.
Published: July 2002

The space–time–frequency distribution of the noise generated in the surf zone was measured in the SandyDuck’97 experiment during September and October 1997. The noise measurements were obtained on a 17-phone, 138-m, bottom-mounted, linear array located along a line perpendicular to the shore at a depth of one to three meters. Concurrent measurements of the location, size, and time evolution of the individual breaking waves directly above the array were made using a video camera mounted on a nearby tower. The measurements of the time history of the noise at individual phones along the array indicate that in regions of wave breaking, the noise contributions are broadband bursts, isolated in time with significant variations in level. A significant number of these broadband bursts exhibit a downward frequency sweep. Similarly, measurements of the time history of the noise observed along the array at selected frequencies show significant variations in both the range extent and the propagation speeds of the noise sources. The paper will present an interpretation of this variability in terms of the space–time distribution of the breaking waves obtained from the video measurements. [Work supported by ONR.]
SANDYDUCK97 angle-time-frequency measurements of breaking wave noise
Authors: Livingston Ellen S. , Newcomb Joal J. , Heitmeyer Richard , Wales Stephen C. , Means Steven L.
Published: July 2002

Low-frequency acoustic measurements (0 to 2400 Hz) were taken in October 1997 as part of the SANDYDUCK97 experiment. These measurements were made on a horizontal bottom-mounted line array deployed in the surf ‘‘transition’’ zone at about 500 m offshore. The array consisted of 64 elements oriented end fire to shore in 6 m of water. Video cameras, mounted on a shoreside tower, monitored the breaking wave events over the transition zone array and in the nearby surf zone during data collection periods. The beamformed array data provide an angle-time-frequency distribution of the breaking wave noise as detected in the transition zone. Comparisons will be made of the angle-time-frequency characteristics from noise fields generated during low-, medium-, and high-surf conditions, with particular attention to the differences between inshore and offshore characteristics. Results from a similar data set obtained during DUCK94 will be presented for comparison as well.
A theoretical investigation of the low-frequency sound generated by breaking waves
Authors: Loewen Mark R. , Farell Cesar E.
Published: July 2002

The important influence of breaking waves on the dynamics of the upper ocean has motivated research into developing techniques for quantitatively measuring the effects of wave breaking in the field. Breaking waves are a major source of sea surface sound and breaking events produce sound at frequencies as low as 10 Hz. Collective bubble cloud oscillations have been shown to be the dominant source of the low-frequency sound. Laboratory experiments have shown that the low-frequency sound generated by breaking is correlated with the amount of wave energy dissipated and the volume of air entrained. Therefore it may be possible to use passive acoustic measurements in the field to obtain estimates of the volume of entrained air and energy dissipated by individual breaking events. Development of a model of the low-frequency sound generated by individual breaking waves is an important step in achieving this goal. A simplified model of the low-frequency sound generated by breaking has been developed based on the approach of Oguz [J. Acoust. Soc. Am. 95(4), 1895–1912 (1994)]. The importance of the simplifying assumptions used in the model and the use of the model as an aid to interpreting field and laboratory measurements will be discussed.
Modeling of electrostatic ultrasonic transducers with micro air-gap structure
Authors: Ge Li-Feng
Published: July 2002

A theoretical model developed by previous papers, i.e., the plate-on-air-spring model or short-tube model (or DK model) [L.-F. Ge, J. Acoust. Soc. Am. 100, 2809 (1996), and Chin. Sci. Bull., Academia Sinica 42, 22 (1997)], has been successfully extended to a generalized case, in which diaphragms of transducers are loaded also by in-plane tensile forces. Based on the dynamic analysis of such an electrostatic transducer, its diaphragm can be considered as a tensile thin plate supported by air-spring, or as a short tube enclosing air, terminated by a flexible tensile diaphragm and grooved backplate as a rigid wall. The physical model and mathematical formulation describing the transducer behavior has been further developed. A comparison between the tensile-plate-on-air-spring model (or TDK model) and the plate-under-tension model (may be termed TD model) [M. J. Anderson et al., J. Acoust. Soc. Am. 97, 262–272 (1995)] is discussed in the paper by an example of predicting the resonant frequencies of a U-grooved backplate transducer with T=100 N/m and Vp=250 V. The fundamental frequency is estimated by the new model at 349 kHz, corresponding pistonlike motion of the diaphragm, and second at 515 kHz, corresponding to the first bending vibration mode. The predictions are more consistent with the measurements reported. [Work supported by the Anhui Education Council Foundation.]
Detection and estimation of microbubble size distribution in blood
Authors: Jenderka Klaus V. , Dietrich Georg , Cobet Ulrich , Urbanek Petr
Published: July 2002

The characterization of the microbubble size distribution in blood is of great practical interest for the design and the use of heart–lung machines and for clinical research. Another application is the continuous estimation of size distribution of ultrasound contrast agents. The measurement system is based on a 2-MHz pulse Doppler device and a special transducer, designed to connect to a 3/8-in. tube. The computer controlled system consists of two simultaneously working channels. The system is self-calibrating. The amplitude of a reference echo from a reflector behind the tube is used for the compensation of different acoustical properties of the tube. The minimal size of detectable gas bubbles and also the resolution of the size distribution is 1 μm in diameter. The detected size distribution will be measured continuously and saved every 5 s. Therefore it is possible to study the time course of the number and the size of gas bubbles, for example, during a heart operation. Showing the effectiveness of an arterial blood filter is done by measurements before and after the filter. Examples of the size distribution of contrast agents in different suspensions versus time after injection will be presented.
Ultrasonic phased array design for reduced crosstalk
Authors: Dodson John , Grosh Karl
Published: July 2002

In recent years, therapeutic ultrasound has received increased attention as a treatment modality for cancer therapy (hyperthermia) and heart arrythmia (ablation surgery). Ultrasonic phased arrays offer the benefit of noninvasive treatment with the flexibility of variable focus and beam steering. In designing and building these arrays, electromechanical isolation is extremely important as interelement crosstalk will degrade array performance. However, manufacturability and cost, constraints which may conflict with the goal of reduced crosstalk, must also be a consideration. Efficient numerical methods present a useful design tool for array design and allow the investigation of structural acoustic phenomena in general. In this paper, a two-dimensional finite-element model for an ultrasonic phased array in contact with the human body is used to study array design. The effects of material selection and geometry for matching layer(s) and interelement structural matrix are examined for their impact on radiation pattern, power input to the fluid domain, and deleterious effect on the electromechanical behavior of the transducers. Finally, design guidelines are formulated and, if possible, compared to experimental results.
Sound power emission measurement and control on a 300-t hydraulic press
Authors: Bronuzzi Fabrizio , Cigna Caterina , Patrucco Mario , Sassone Maurizio
Published: July 2002

The paper summarizes the results of research work carried out to evaluate properly the noise emission characteristics of a 300-t hydraulic press in a complex noise propagation environment. On the basis of the collected data, some control measures were designed, and the results are discussed. As well known, noise is widely affected by the acoustical environment the sound propagates through, and an effective description of the source emission properties is required for the control design. Traditional measurement techniques are not the best for this purpose, because the information on acoustic pressure depends on the environment. To overcome this problem, the emitted acoustic power was then evaluated by means of acoustic intensity measurements; in such a way it is possible to qualify real and complex sound sources, locating the contribution of single parts that participate in sound generation. Resulting maps describing the contribution of every single part, an effective individuation of improvement strategies was possible, since the priorities for intervention were available. A new campaign of sound intensity measurements confirmed the expected control measures’ results, and the direct measurements of the operators’ exposure confirmed the success of the intervention.
Spectral versus harmonic information for timbre: Pilot and experimental results
Authors: Mencl Einar
Published: July 2002

This work summarizes results from six experiments on steady-state timbre perception. The primary variable of interest was the physical similarity of tones within each trial: tones were either similar by virtue of their spectral envelope (i.e., they shared resonance characteristics) or their harmonic envelope (i.e., they shared overtone characteristics). These two continua were chosen as candidates for basic perceptual dimensions because (1) they each contain specific types of information about the sound source/event, and (2) a cursory computational analysis suggests that very different processes are needed to extract information about resonances versus overtones from the auditory input. It was reasoned that if different subsystems subserve the processing of timbre along each of these two dimensions, then performance on perceptual tasks would dissociate under appropriate experimental manipulations. These included (1) attentional focus and response type (timbre similarity judgment, pitch direction judgment, or pitch contour judgment), (2) perceptual priming, and (3) auditory masking. Results demonstrate that in general both dimensions of similarity can support perceptual priming, but also show specific dissociations which inform the understanding of steady-state timbre perception. [Portions of this research were supported by NSF Grant No. DBS-9222358 to Jamshed Bharucha.]
Lexical competition in spoken word recognition by younger and older adults: A comparison of the rime cognate, neighborhood, and cohort
Authors: Sommers Mitchell S. , Amano Shigeaki
Published: July 2002

A central issue in research on spoken word recognition has been to specify the lexical candidates that are initially activated and compete during lexical discrimination. Amano [J. Mem. Lang. (submitted)] has recently proposed a new candidate set, the rime cognate (RC), which suggests that the set of potential lexical candidates consists of all items containing the same phoneme sequence as the rime (vowel nucleus plus coda) of that word. The present study was designed to compare the ability of the RC and two other sets, the neighborhood and cohort, to account for spoken word recognition in both younger and older adults. Density measures derived from the neighborhood were significantly correlated with identification scores for younger and older subjects. In contrast, RC density metrics were significantly correlated with identification scores only for older adults. Both neighborhood and RC density measures accounted for a greater percentage of the variance in spoken word recognition for older than for younger listeners. Metrics derived from the cohort were not significantly correlated with identification scores for either younger or older adults. The implications of these findings for several current models of spoken word recognition are discussed. [Work supported by the Brookdale foundation.]
Integration of auditory and visual speech information
Authors: Hall Michael D. , Smeele Paula M. T. , Kuhl Patricia K.
Published: July 2002

The influence of visual information on auditory speech perception can be observed under conditions where the two sources of information are discrepant [McGurk and MacDonald (1976)]. Recent studies from our laboratory [Hall et al. (1996)] focused on one such condition, where a face producing /b/ is combined with a dubbed auditory /g/ token, resulting in the frequent auditory perception of /bg/. These studies used auditory tokens that varied in quality, and have suggested that the probability of auditory consonant identification as /g/ was sufficient to predict the probability of /bg/ responses. The current study extended this approach to the converse conditions, where an auditory /b/ was dubbed on a visual /g/ production, which typically results in the frequent auditory perception of /d/ or /th/. Additionally, similarity ratings were collected for sets of auditory /g/ and /b/ stimuli, as well as for both types of auditory-visual conditions (/g/+/b/ and /b/+/g/). Multidimensional scaling (MDS) of these ratings was used to determine whether auditory category structure predicts MDS solutions for combined auditory and visual information. Implications of the results for the nature of auditory-visual speech integration will be discussed. [Work supported by NICHD.]