bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between behavioral and auditory brainstem response thresholds in infants and adults.
Authors: Werner Lynne A. , Rickard Mancl Lisa , Folsom Richard C.
Published: October 2005

It has been previously reported [L. A. Werner etal., J. Acoust. Soc. Am. Suppl. 1 88, S18 (1990)] that for 3-month-old infants, there is a modest but significant correlation between detection thresholds measured behaviorally and using the auditory brainstem response (ABR) for tone pips at 4 and 8 kHz, but not at 1 kHz. It has been hypothesized that one should not see a correlation between behavioral and ABR thresholds among young normal-hearing adults, since variability in hearing levels in this group would be small, and that as infants’ thresholds approached those of adults (around 6 months of age), the correlations we observed at 3 months would decrease. In the current study, detection thresholds were obtained from 20 to 30 yr olds at 1, 4, and 8 kHz and from 6-month olds at 8 kHz using behavioral and ABR measures to test these hypotheses. The stimuli were tone pips with 2-cycle rise and fall and no steady state. ABR thresholds were measured by reducing the level from 20 dBnHL until no response was observed, then increasing the level until the response reappeared. Behavioral thresholds were estimated adaptively, and defined as the average of the last 8 reversals obtained.

For infants, a trial was considered ‘‘correct’’ if an observer said ‘‘yes’’ when a signal was presented to the infant, or ‘‘no’’ when no signal was presented. The observer had no prior knowledge of trial type. Adults were instructed to respond whenever they heard the tone pips. The correlation between ABR and behavioral threshold for adults was not significant at 1 or 4 kHz. Similarly, there was no correlation between the two measures for 6-month olds at 8 kHz. The correlation between ABR and behavioral thresholds for adults was significant, however, at 8 kHz. These findings suggest that variability associated with development of the auditory system is responsible for the ABR-behavioral threshold correlation seen at young ages. [Work supported by NIH DC00520.]
Stimulus presentation formats in training paradigms for tactile aids.
Authors: Weisenberger Janet M.
Published: October 2005

Previous studies involving tactile aids for speech perception conducted in our laboratory have typically employed a training paradigm consisting of initial training with single-item speech stimuli in a citation-style live-voice presentation, followed by later training with connected discourse. This selection of training procedures was based on the assumption that for recognition of vibratory patterns corresponding to particular phonemes and/or syllables, such initial single-item presentation promoted rapid learning. However, given the sometimes substantial differences in the acoustic waveforms of items presented citation style or in the context of connected speech, it is possible that early initial training with citation-style stimuli would actually impair later performance with connected speech. Thus, although high levels of performance for users of tactile aids with connected speech have previously been obtained, it is possible that initial training with stimulus items in carrier phrases would be superior to citation-style presentation. In the present study, two groups of subjects were trained to use the Queen’s University tactile vocoder; one group was trained initially with single-item stimuli presented citation style, and the other group was trained initially with stimuli presented in carrier phrases. Both groups were later tested in a connected discourse tracking task. Preliminary analysis of the results suggests no differences between the two groups, suggesting that citation-style presentation and carrier-phrase presentation have equivalent effects on later connected speech performance. [Work supported by NIH.]
Objective measures of hearing loss compensation techniques.
Authors: Tungthangthum Apichat , Rutledge Janet C.
Published: October 2005

Many techniques have been developed to compensate for hearing losses. With each new implementation, a subjective test was needed to verify its quality. In this study, objective measures to predict the results of a subjective test have been developed. A database of results from subjective testing based on four compensation techniques, multichannel linear gain, multichannel compression, TVFD [J. C. Rutledge and M. A. Clements, Proc. IEEE ICASSP, 3641–3644 (1991)], and flat gain amplification, were used to develop the objective measures. The measures can be computed directly from the original speech waveform and a speech waveform processed using the compensation technique. Some parameters such as the energy in each band are measured from the original speech waveform and used as the input to a regression analysis model to calculate the coefficients of the model. Then the same type of parameters are measured from the processed speech waveform with some constraints of the hearing loss, such as hearing threshold, incorporated. The objective measures will be used to predict the performance quality of new techniques that are being developed. Subsequent subjective tests will then be used to fine tune the objective measures. It is hoped that the use of these objective measures will streamline the process of bringing new compensation techniques into fruition.
The improvement of hearing ability after stimulating human cochlear region with low-intensity focused amplitude-modulated ultrasound.
Authors: Zeng Shengke , Beard Richard B.
Published: October 2005

The experiment was designed to investigate the effect of low-intensity ultrasound on audibility after stimulating the human cochlea for a short radiation period [S. Zeng, M. S. thesis, Drexel Univ. (1990)]. The ultrasound carrier was focused, and amplitude modulated by an auditory signal. The intensity of the ultrasound in the cochlear region was no higher than 104 mW/cm2 SPTP or 15.6 mW/cm2 SPTA. The total radiation period was 30–60 min. Direct focusing of ultrasound on the cochlea was verified by observation of the subject’s ultrasound auditory sensation. This sensation was stimulated by the auditory signal, demodulated from the ultrasound carrier in the cochlear region [I. A. Vartanyan and E. M. Tsirul’nikov, Fiz. Cheloveka 11 (3), 386–394 (1985)]. The audibility threshold of the subjects was tested before and after the modulated-ultrasound radiation. After the radiation, a decrease of the audibility threshold was observed. This audibility improvement was frequency dependent. For normal-hearing subjects, the improvement was 7.4 dB (mean) at 125 Hz and decreased linearly to 0.8 dB (mean) at 4 kHz. Above 4 kHz, the improvement was not significant. [This research was partially supported by Electro-Stim Corp.]
Observation of the midfrequency enhancement of tone bursts backscattered by a thin spherical shell in water.
Authors: Kaduchak Gregory
Published: October 2005

A prominent feature predicted for the backscattering by thin spherical shells is an enhancement of the guided wave contributions in the midfrequency range [L. G. Zhang etal., J. Acoust. Soc. Am. 91, 1862–1874 (1992)]. This feature may be useful for certain inverse problems and is associated with a strongly coupled slightly subsonic wave denoted by some authors as the a0− wave. The present research gives a comparison between a ray analysis and experiments in which tone bursts having carrier frequencies ω=kc in the range 35<ka<70 were incident on an empty stainless steel shell in water. The sphere’s radius to thickness ratio is a/h=43.8. Time records of echoes provided a means for measuring the guided wave contribution relative to that of the specular reflection. As predicted the guided wave echo can be over three times larger than the specular echo and the ka dependence generally follows the predicted hump. [Work supported by ONR. The author acknowledges the advice of P. L. Marston.]
Impulse response for backscattering by a thin spherical shell displayed in time and frequency.
Authors: Hughes D. H.
Published: October 2005

Time-frequency resolutions of the acoustical scattering from submerged targets utilizing exact form functions have been given by Yen etal. [J. Acoust. Soc. Am. 87, 2359–2370 (1990)]. Spectrograms of backscattered signals from a thin spherical are computed in the present research as smoothed Wigner distributions employing an algorithm given by Nuttall [NUSC Technical Report 8785 (1990)]. For the response to an impulse, the underlying dynamics are discussed in light of recent investigations by several authors working from different but complementary viewpoints. A deficiency in the spectrogram’s ability to simultaneously resolve the instantaneous time-frequency content of backscattered signals is exploited to display either the underlying resonant structure of steady-state scattering or the transient response to wideband impulses or tone bursts. The spectrograms identify features associated with the midfrequency enhancement present in corresponding time-domain plots given by L. G. Zhang etal. [J. Acoust. Soc. Am. 91, 1862–1874 (1992)]. Prompt features associated with the high-frequency enhancements are also evident. [Work supported by ONR.]
Diffraction of evanescent wave tone bursts on membrane in air and related observations of bursts guided by plates in water.
Authors: Matula Thomas J.
Published: October 2005

A previously described electromagnetic acoustic transducer (EMAT) was used to generate subsonic wave tone bursts on membranes [T. J. Matula and P. L. Marston, J. Acoust. Soc. Am. Suppl. 1 88, S167–S168 (1990)]. In the present research, the evanescent wave field in the air surrounding the membrane was studied. Diffraction of the burst by a sharp edge in the air was also observed. The diffracted signal was measured using a microphone as a function of the gap h between the membrane and a razor edge. The diffracted pressure decreases exponentially with increasing h as expected from an approximate analysis of edge diffraction of evanescent waves [L. B. Felsen, J. Opt. Soc. Am. 66, 751–760 (1976)]. The importance of such diffraction is that it produces far-field radiation of energy that otherwise would be trapped to a membrane or plate in the absence of scattering. In related work an EMAT is used to generate tone bursts of bending waves on an aluminum plate. The bursts propagate down the plate into water where the surrounding wave field is probed. [Work supported by ONR. The author acknowledges the advice of P. L. Marston.]
Comparison of acoustical images with cylindrical holograms.
Authors: Gaumond Charles F. , Sarkissian Angie , Williams Earl G. , Yoder Timothy J.
Published: October 2005

For this comparison, space-time images are generated from broadband bistatic scattering data. Two imaging methods are used: an extension of reflection tomography [P. B. Abraham and C. F. Gaumond, J. Acoust. Soc. Am. 82, 1303–1314 (1987)] and far-field cylindrical holography. The sharpness of the space-time impulse response, or resolution, as well as the appearance of scattering mechanisms such as reflection, diffraction, and plate wave propagation are shown for the case of a right circular cylindrical shell with hemispherical endcaps.
Experimental evaluation of backscattering from finite internally loaded cylindrical shells.
Authors: Corrado Charles N. , Conti Matthew , Dyer Ira
Published: October 2005

Dynamic interaction between a shell and internal structural elements may be significant in backscattering. These interactions are of particular interest to us at frequencies where wavelengths are comparable to characteristic discontinuity lengths of the structure. Scattering by three cylindrical shell models has been measured to delineate regimes where the influence of internal structures is significant, and to highlight fundamental backscattering processes common to more complex structures. The models are: an empty shell, a duplicate empty shell with unequally spaced ribs, and a duplicate ribbed shell with resiliently mounted, wave-bearing internal structural elements. The measurements were conducted with wide-band pulses covering the frequency band of 2.75<ka<10.5 corresponding to 3/4 to 3 times the ring frequency of the empty shell. The internal structures are found to cause significant changes in target strength at all angles of incidence away from beam aspect, and throughout the frequency range studied. The backscattered signature in the time domain shows an increased initial peak response induced by the internal structures, as well as group delay and decay rate properties induced by shell discontinuities and by interaction between the shell and the internal structures. [The authors acknowledge valuable inputs from J. R. Fricke and Y. P. Guo of MIT, and NRL for acquisition of the backscatter data. Research sponsored by ONR.]
Coarticulation in Russian unstressed vowels.
Authors: Evans-Romaine David K.
Published: October 2005

Studies of vowel-to-vowel coarticulation in Russian have generally found vowels in VCV sequences to have little influence on each other’s articulation. This has been attributed to Russian’s contrastive palatalization, which is assumed to block coarticulation by preventing the pharynx and tongue body from moving smoothly from one vowel configuration to the next during stop closure. If this is correct, coarticulation should be minimal even for reduced vowels. This hypothesis was tested by examining coarticulation in the nonfront reduced vowels of Russian. Here, F1 and F2 were measured at the onset, center, and offset of five repetitions of prestress /o/, poststress /o/, and stressed /a/ produced by native speakers in /tVb——b(j)V‘‘tilded el’’/ and /pVd—— d(j)V‘‘tilted el’’/ nonsense words. Posttarget consonants were plain or palatalized; flanking vowels were /i,a,u/, symmetrical. All speakers showed substantial coarticulation throughout the poststress target, during the first half of prestress target, and in the onset of stressed target. These results suggest that contrastive palatalization does not preclude significant vowel-to-vowel coarticulation.
Using the method of adjustment to study vowel spaces.
Authors: Johnson Keith , Wright Richard , Flemming Edward
Published: October 2005

Comparing the acoustic vowel spaces of different dialects or languages is fraught with peril because acoustic measurements confound personal and linguistic information. The study to be reported addressed this problem by using the method of adjustment. Listeners were asked to adjust the F1 and F2 of synthetic vowels to produce a perceptual match between the synthetic vowel and the vowel sound they would expect to hear in a visually presented word. The monosyllabic test words represented ten or eleven different vowel qualities (depending on dialect) for American English speakers. The listeners adjusted F1 and F2 by moving a mouse cursor, clicking the mouse button to hear the vowel sound indicated by the location of the cursor on a CRT. F3, F4, and the formant bandwidths were estimated by regression from previously reported acoustic data. Preliminary results suggested that: (1) Speakers of the same dialect were very consistent with each other; within subject variability (which was small) accounted for about 70% of all within vowel variability. (2) The method revealed perceptual vowel space differences between speakers of different dialects of American English. (3) Differences between monolingual and bilingual speakers of English from the same language community were also found. [Work supported by NIH.]
Computational comparison of broadband acoustic models.
Authors: Brill Michael H. , Eller Anthony I.
Published: October 2005

Broadband acoustic propagation models vary greatly in their computation times. To define the speed-versus-accuracy tradeoffs, two questions are addressed: (1) For ducted environments, how does the parabolic equation (PE) model compare with the faster Labianca virtual-mode model (VM) and the FAME eigenray part of the generic sonar model (GSM)? (2) In nonducted environments, must a GSM complex transmission loss (TL) be computed for all the signal frequencies, or is a single frequency of computation sufficient (i.e., is it fair to assume that the only frequency dependence in the complex-TL phase is in the ray time delay)? To answer these questions, the effects of the computed complex-TL on sine-wave-burst and HFM-burst signals are presented. The multipath arrival structures of the environments enforced a 4-s received-signal duration, and the transmit signals enforced a bandwidth of 200 Hz. The results are as follows: (1) A weak duct shows favorable comparison between GSM, VM, and PE models; however, a strong duct does not, and in fact reveals numerical instability in the PE computations. (2) Single-frequency GSM captures the basic arrival structure of multiple-frequency GSM, but the multipath interference is different and sensitive to the dominant signal frequency. It is concluded that GSM (but not single-frequency GSM) may in most practical cases yield adequate predictions for the acoustic filtering of broadband signals.
Comparison of numerical predictions for transmission loss and reverberation levels in shallow waters.
Authors: Gray G. , Gaunaurd G. C.
Published: October 2005

Since there are no models to currently predict transmission losses (TL) and reverberation levels (RL) for sound propagation problems in shallow waters, what is customarily done to estimate these parameters is to use various standard numerical codes in the same form as they were originally developed for deep waters. This introduces a variety of errors that one must live with, until suitable models are specifically developed for the various shallow water environments of interest. In order to begin to understand the nature and size of these errors (which could often be larger than 60 dB, i.e., that is a factor greater than one million!), half-a-dozen commonly used TL and RL prediction codes have been considered and have been applied to six geographical sites and to fourteen (conceptual but realistic) configurational cases. The models used are the generic sonar model (GSM), the BAM, COLOSSUS, NISSM, RAYMODE, RASP, and RUMBLE. An extensive comparison between the predictions of all these codes in all the cases and sites was carried out, and the results were compared to the (sparse) available measured data. An N.S.W.C. report with the details is in preparation. The study reveals that COLOSSUS provides the ‘‘best’’ TL predictions (i.e., closest to the data) and RASP the best ones for RL, in the shallow water environments found in the continental shelves.
Massively parallel simulation of the ideal wedge benchmark and variations.
Authors: Krutar R. A. , Numrich S. K. , Cole J. B.
Published: October 2005

An efficient lattice gas scheme for simulating the propagation and scattering of underwater sound over the entire near- to far-field range has been implemented on a Connection Machine at NRL. This method has been tested on the ideal wedge benchmark. At 2-m resolution 8000 time steps were calculated and 381 frames consisting of 512×512 cells each were rendered (a total of 2 billion cell updates) in less than 10 min. The utility of this simulation technique is illustrated by introducing variations into the basic problem, that would be difficult to model using normal mode theory.
Parallel and vector algorithms for solving the underwater parabolic equation with a finite element model.
Authors: Zingarelli R. A.
Published: October 2005

Rapid solution of the parabolic equation via the finite element method in a range-dependent environment is necessary for practical applications. Several backward recurrence relations inherent in the solution inhibit efficient utilization of specialized computer hardware. Three algorithms suitable for vector, parallel, and massively parallel hardware are presented. Efficiency, speed, numerical stability, and application to existing problems are discussed. [Work supported by ONT.]
A three-dimensional analysis of acoustic propagation in a penetrable wedge.
Authors: Deane Grant B.
Published: October 2005

The method of source images is used to develop an analytical solution for the three-dimensional acoustic field in a penetrable wedge. The acoustic field for a harmonic, point source is computed assuming isovelocity sound field profiles in the water and sediment. The solution for the field consists of a sum of contributions due to source images and gives the sound field at any point in the water or sediment of the wedge. This analysis differs from the earlier work of Deane and Tindle (submitted to JASA, 10 December 1991), which is restricted to propagation in a plane perpendicular to the wedge apex. The present work uses a Bessel function expansion that results in a computationally efficient solution to the field which is valid throughout the wedge.
Recursive ray acoustics for three-dimensional sound-speed profiles.
Authors: Ziomek Lawrence J.
Published: October 2005

A recursive ray acoustics (RRA) algorithm for three-dimensional sound-speed profiles is presented. The RRA algorithm is simple, fast, and accurate and uses arc length as the independent variable. It can be used to compute the position, angles of propagation, travel time, and path length along a ray path. The accuracy of the RRA algorithm was tested by comparing its results with those obtained from a ray acoustics algorithm that requires the solution of a system of four, first-order, ordinary differential equations (ODEs). The ODE algorithm, which uses horizontal range as the independent variable, can only handle one-dimensional, depth-dependent, sound-speed profiles (SSPs). Therefore, five standard, depth-dependent, SSPs were used to test the two algorithms. The results from the ODE algorithm were treated as the benchmark, with respect to accuracy, for comparison purposes. The RRA algorithm proved to be very accurate for the test cases tried. After the accuracy of the RRA algorithm was validated by using one-dimensional SSPs, its three-dimensional sound-speed capability was also tested. [Work supported by DARPA and the Naval Postgraduate School Direct Funded Research Program, sponsored by ONR, Code 1125 OA.]
Acoustic modeling through a Mediterranean water lens (Meddy).
Authors: Browning David G. , Botseas George , Podeszwa Eugene M.
Published: October 2005

Mediterranean water lenses (Meddies), as reported by Armi [L. Armi and W. Zenk, J. Phys. Oceanogr. 14, 1560–1576 (1984)], are small warm-core eddies with a large width (100 km) to thickness (0.9 km) ratio. Centered at a depth of approximately 1000 m, they were observed in the Canary Basin of the North Atlantic Ocean. These are unlike many warm-core eddies that extend to or near the surface [P. A. Nysen, P. Scully-Power, and D. G. Browning, J. Acoust. Soc. Am. 63, 1381–1388 (1978)], and hence may cause unique propagation anomalies for certain source–receiver configurations. A set of reported oceanographic specifications of a Meddy was converted to sound-speed profiles which were merged with historical data below a depth of 2000 m. Acoustic modeling runs at 200 Hz were made across the Meddy using the IFD/PE model. The results were compared to normal propagation predictions for the area. The characteristic shift of the convergence zones is observed, but as might be expected the impact is relatively small for shallow source–receiver configurations and greatest for source and receiver depths near the center of the Meddy.
Acoustical measurements and instrumentation.
Authors: Rasmussen Gunnar
Published: October 2005

Acoustical measurements are fully accepted as precise and well-defined techniques for establishment of noise and sound quality criteria. A long line of national standards has enabled the creation of a large database with comparable results supporting confidence in the field of acoustics. The half-inch microphone is now the industry standard minimizing errors related to operator ignorance. The use of correctly measured rms values is taken for granted due to progress in instrumentation detectors. The acousticians have available well-standardized filters for frequency analysis. Intensity measuring techniques are now available along with calibration techniques offering the acoustician the possibility to contribute to the field of structural vibration, machine diagnostics, product development, quality control on machines and products in general, condition monitoring, etc. Acoustic transducers and techniques are used for gas analysis, medical diagnostics, and many other fields. The acoustician who understands physics, dynamics, and wave propagation has a great chance to influence the technical process. Frequency analysis of steady continuous signals has been taught very well in the educational sector along with finite element modeling in the context of digital processing on computer-based systems. The far more important treatment of real world dynamic and often nonlinear and distributed processes represents the future challenge to the engineer and therefore to the researcher and educator.
Pioneering in acoustics: Hearing aid transducers.
Authors: Killion Mead C.
Published: October 2005

Three men, Sam Lybarger, Hugh Knowles, and Elmer Carlson, have been responsible for a disproportionate share of the hearing-aid developments over the last 60 yr. Their technical contributions, and the importance of those contributions to better hearing aids, will be reviewed. Two of them are still healthy and productive, indicating that making the world better for the hearing impaired may slow the aging process.
Underwater transducers.
Authors: Ehrlich Stanley L.
Published: October 2005

The set of underwater acoustic transducers of primary interest in this presentation is employed to provide electrical signals to sonar receivers, to accept electrical outputs from sonar transmitters, or both. Several different transducer element and array configurations will be selected for discussion based on the author’s personal experience and the open literature in reports and journals, including review papers and patents. A brief overview of the active materials and mechanisms used and the need for further improvement will be noted. Also, the impact of system synthesis versus the simpler separate element design will be discussed, since this is a major problem in ‘‘big’’ sonars. Finally, an attempt will be made to estimate the future trends in research and development of underwater transducers.
Acoustics and orchestral sound.
Authors: Meyer Jürgen
Published: October 2005

The tone quality of an orchestra rests on the cooperation of a multitude of differing instruments which are used partly in solo fashion and partly gathered in groups; it is furthermore shaped by the spatial extension of the ensemble and by the influence of room acoustics. Acoustic measurement procedures permit an analysis and description of tonal characteristics of individual instruments in regards to sound power output, spectral composition, time-dependent fine structure, and orientation dependence of sound radiation. Appreciation of the full orchestral sound, on the other hand, requires consideration of sound transit times within the orchestra with the associated problem of playing together, as well as variations in wall reflection times for different instrument positions. The effect of dynamics and masking, the chorus effect and the seating arrangement of the strings , and spectral and time-dependent tone construction will be demonstrated with the assistance of the Weber State University Symphony Orchestra, prepared by its regular conductor, Professor Michael Palumbo. Sound examples are taken largely from the overture to the opera ‘‘Der Freischūtz’’ by Carl Maria von Weber. In conclusion, the orchestra will perform the entire overture directed by Professor Meyer.
Temporary threshold shift in organists’ hearing.
Authors: Brock Laura E. , Nábělek Igor V.
Published: October 2005

The purpose of the study was to determine if organists experience temporary threshold shifts of hearing during a typical practice session. Ten organists (6 male, 4 female) aged 23–54 yr were evaluated with hearing history questionnaire, otoscopic examination, otologic questionnaire, and pure tone audiometry. Bond conduction testing verified no conductive hearing loss in any subject. After audiometric examination each organist played the organ for 2 h under identical practice conditions and then was retested with pure tones to assess temporary threshold shift (TTS) in hearing. There was no significant TTS when data were statistically analyzed, however TTSs as large as 15 dB were recorded in individual cases. Spectral content of the organ music played in the sessions was found to have a dominant frequency at around 500–750 Hz.a)Present address: Dept. of Audiology, Pinehurst Surgical Clinic, P.A., P.O. Box 2000, Pinehurst, NC 28374.
Observables in short pulse scattering and their relation to structural features.
Authors: Felsen Leopold B.
Published: October 2005

Short pulse (SP) scattering from submerged structures is related to structural features that leave their imprint via observables in the scattered signature. Because of the SP high resolution, some of the time-domain (TD) observables are isolated spikes and dips while others exhibit quasiperiodic or periodic oscillations. To relate the data to the structure that generates it, as required for modifying the response or for classification and identification, it is necessary to parametrize the scattering process in terms of relevant wave phenomena in the configurational (space-time) as well as the spectral (wave-number–frequency) domains. This can be done by systematic construction of a catalog of observables due to configurations with different structural features. This review summarizes SP results from various relatively simple test problems, with emphasis on configurational, spectral, and hybrid wave objects that are useful for synthesis as well as data processing. Such wave objects include TD edge-diffracted fields, TD leaky and Floquet modes (both traveling and resonant), etc., which can be combined into a hybrid TD ray-acoustic observable-based algorithm. [Work supported by ONR.]
Acoustic field visualizations using short pulse/wide band excitation.
Authors: Blake William K. , Feit David
Published: October 2005

Acoustic fields radiated and/or scattered by elastic structures are visualized in a number of different ways. This presentation illustrates two possible formats using wide band/short pulse excitation of simple idealized structural configurations. First, the field radiated by a fluid-loaded elastic plate excited by a localized transient force is investigated. The field is calculated using the classical Bernoulli–Euler equations for the plate response and then compared to results obtained using the Timoshenko–Mindlin plate equations. The transient response is visualized by color coding the pressure levels and displaying them in either rectangular or polar formats, using angle of observation and time as the coordinates. With the fluid sound speed as a reference, precursors were observed in both cases, the nature of which depends on the observation angle and the plate theory used. Second, images are discussed that were obtained from processing returns of wide band acoustic pulses scattered by a body as it rotates relative to the source. The rotation angle determines the lateral, or cross-range resolution, while the signal bandwidth determines the down-range resolution by revealing time domain separation. Alternative images show rotation-angle/down-range loci or cross-range/down-range loci. The displays divulge the existence and location of different classes of structural acoustic phenomena. For a detailed study of the scatterers structure, a joint time-frequency representation at fixed body angles can reveal some inherent features that do not stand out in a single domain representation.
Effects of departures from periodicity on the frequency domain and short pulse acoustic scattering from finite soft and rigid flat strip arrays.
Authors: Carin L. , Hsu T.-T. , Felsen Leopold B.
Published: October 2005

Many structures of interest contain regularly spaced elements that leave their imprint on the acoustic scattered field. For periodic arrangements, even a few elements may imprint on the scattered field the signature of the periodic structure Floquet modes that characterize an infinite array [L. Carin and L. B. Felsen, J. Acoust. Soc. Am. 90, 2355(A) (1991)]. Explored here, for various collections of flat, soft, and rigid strip scatterers, is how departures from periodicity due to array truncation, as well as displacement, change in size, etc., of individual and groups of elements affects the time-harmonic and short pulse plane wave scattered response. Reference solutions obtained numerically by direct integration of a (spectral domain)–(moment method) procedure are interpreted phenomenologically through asymptotic reductions to yield truncation edge diffracted contributions, local Floquet modes from the overall bulk of the array, and individual scatterings from displaced elements. The contracting behavior of these contributions under high-frequency time-harmonic and short-pulse conditions is noted and interpreted. [Work supported by ONR.]
Backscattered signature features in the combined time-frequency domain of submerged targets insonified by ideal sound impulses.
Authors: Strifors Hans C. , Gaunaurd G. C.
Published: October 2005

The backscattered pulses resulting when ideal acoustic impulses with plane wave fronts are incident on various submerged structures are studied. The structures are selected to be solid steel or granite spheres, and also spherical steel shells containing either air or water. A time-windowed Fourier transform (TWFT) and a pseudo-Wigner distribution (PWD) of the backscattered pulses are computed and displayed, in both cases employing a Gaussian time window. It is demonstrated that each of these distributions can extract and exhibit informative features that agree well with the general time development of the various kinds of resonances usually present in the considered frequency band (in this case: 0≤k1a≤60) of these bodies. Bringing the returned signature information closer to its physical causes is a prime merit of those time-frequency distributions and of the displays they produce. Another one of their desirable properties is their ability to reduce the number of dominant signature features present in the echo while preserving the time progression of the extracted features. Both these properties will improve the target-recognition capability ordinarily furnished by the standard sonar cross sections of the considered targets.
Mid-frequency enhancement of the impulse response of a thin spherical shell: Ray approximation and a related frequency-domain analysis.
Authors: Marston Philip L.
Published: October 2005

A ray approximation was previously applied to the mid-frequency enhancement of the backscattering that occurs for ka close to the shell radius to thickness ratio a/h for thin shells [L. Zhang etal., J. Acoust. Soc. Am. 90, 2341(A) (1991) and L. G. Zhang etal., J. Acoust. Soc. Am. 91, 1862–1874 (1992) ]. The enhancement is primarily associated with the earliest guided ray contribution (that circumnavigates only the backside of the shell) of the slightly subsonic guided wave denoted by l=a0− by some authors. This ray contributes a large wave packet to the impulse response that is approximated in the present work. It is shown that the form function contribution ‖fm=0,l‖ is well approximated by a Gaussian centered on the ka where the damping βl≊1/π Np/rad. The resulting time-domain wave packet has an approximate Gaussian envelope and carrier frequency associated with that spectrum. The envelope amplitude is affected by the ka dependence of the phase velocity cl. This ray analysis, although incomplete, also gives insight into the background-subtracted steady-state form function. [Work supported by ONR.]
Types of dialect variation.
Authors: Yaeger-Dror Malcah
Published: October 2005

Speech variation is of importance to workers in automated speech recognition and synthesis. This paper will discuss specific sources of variability that are of practical concern to these researchers. Quantitative evidence will be presented from American dialects of both English and French to demonstrate how vowel formant frequency variation is correlated with both the sonority of intrasyllabic following consonants and with prosodic information. Evidence will also be presented from analysis of vowel formant information from various speech ‘‘styles’’ and ‘‘registers’’ to demonstrate how researchers can appropriately integrate such variation into synthesis modules. Evidence for several sources of variation will be presented, and both theoretical and practical conclusions will be drawn from the evidence. [Work partially supported by NSF.]
Controlling for dialect in contextless vowel identification: Revisiting the Peterson–Barney experiment.
Authors: Ash Sharon
Published: October 2005

In an early study on the spectrographic measurement of vowels, Peterson and Barney proposed that listeners would interpret a vowel heard in isolation as the phoneme in their own speech corresponding to that sound [G. E. Peterson and H. L. Barney, J. Acoust. Soc. Am. 24, 175–184 (1952)]. The present study is based on their experiment and aims to test their hypothesis by controlling for the dialect of both speakers and listeners. In this investigation, listeners in Philadelphia, Birmingham, and Chicago were asked to recognize 14 vowel phonemes pronounced in the frame /k—d/ by speakers from the same three cities. It is found that for most firmly established variables, local listeners have an advantage in identifying phonemes pronounced by speakers of their own dialect. However, for new changes in progress and for at least one well-known stable variable, local listeners have great difficulty identifying the vowel, nearly as much as do listeners from other areas. Finally, both local and nonlocal listeners make a significant number of errors in identifying certain phonemes. The findings are explained in terms of chain shifts and the phonetics of the test tokens. [Work supported by NSF.]
The possible relationship of longitudinal basilar membrane stiffness to the distribution of spontaneous otoacoustic emission frequencies.
Authors: Talmadge C. , Tubis A.
Published: October 2005

Eberhard Zwicker and his co-workers have focused attention on the characteristic frequency spacing (≊0.4 Bark) of families of very narrow-band spontaneous otoacoustic emissions (SOAE’s). To date, the only type of cochlear model that has been used to describe such SOAE families is the adhoc one in which negative damping with stabilizing nonlinearity is localized so as to correspond tonotopically to the SOAE frequencies. Another type of model is proposed for these SOAE families based on their analogy with the narrow-band spectra of wind and bowed-string musical instruments resulting from self-sustained oscillations that reflect the normal modes of the underlying vibrating air column or string. It is assumed that the basilar membrane has longitudinal stiffness (at least at low levels of displacement), and a study was done to determine to what extent the place dependence of the longitudinal wave velocity can be chosen so as to give membrane modes with the characteristic SOAE frequency spacings. The effect of adding such longitudinal coupling to the usual nonlinear-active damping is explored formally and via numerical simulations. [Work supported by NIH-NIDCD Grant No. DC-00307.]
Binaural loudness summation: Better and less than ‘‘perfect.’’
Authors: Mulligan B. E.
Published: October 2005

Monaural and binaural loudness functions of 500- and 1000-Hz pulsed tones were obtained by loudness estimation under the same conditions where binaural loudness summation previously was found to vary as a function of induced adaptation [B. E. Mulligan etal., Proc. Int. Soc. Psychophys. 1–5 (1991)]. Comparisons of loudness function parameters indicate that slopes of all functions tend to be greater under conditions of induced adaptation, but differences between monaural and binaural slopes do not appear to be statistically reliable. Under adapted conditions, binaural/monaural loudness ratios and binaural summation levels exceed ‘‘perfect’’ doubling (ratio of 2 and level of about 10 dB). Under nonadapted conditions, however, loudness ratios and summation levels are less than ‘‘perfect’’ (ratios of approximately 1.4 and levels of about 5–6 dB).
Loudness levels of three complex stimuli and model predictions.
Authors: Jeng Patricia S. , Hall Joseph L. , Levitt Harry
Published: October 2005

Loudness levels were measured for three test stimuli (speech, narrow-band noise, and square wave) at three levels in three test conditions (test stimulus in quiet, test stimulus in presence of masker, and total loudness of test stimulus plus masker). Loudness levels were measured in the traditional way by matching loudness of the test stimulus to that of a 1-kHz tone. In addition, loudness levels were measured using a narrow-band noise as the reference stimulus. The bandwidth of the narrow-band noise used as test stimulus (NBN-150) was 150 Hz, and the bandwidth of the narrow-band reference stimulus (NBN-120) was 120 Hz. Both stimuli were arithmetically centered at 1 kHz. The loudness level functions for speech and for NBN-150 have slopes of approximately unity. However, the loudness level function for the square wave has a slope of greater than unity below about 50 dB SL and the slope decreases above about 50 dB SL. Loudness predictions of two models are computed and compared to the experimental measurement. [Work of P. S. J. done as a consultant at AT&T Bell Laboratories, Acoustics Research Department.]
The use of frequency domain kurtosis in the assessment of industrial noise environments for hearing conservation purposes.
Authors: Ahroon William A. , Lei Sheau-Fang , Davis Robert I. , Hamernik Roger P.
Published: October 2005

Industrial noise environments are frequently characterized by combinations of noise impacts superimposed on a steady-state continuous noise background. Digital techniques were used to synthesize complex noise environments containing random impulses with random peak SPL’s up to 125 dB. Four groups of chinchillas were exposed to one of three different complex noise environments whose sound exposure levels and spectra were similar to a fourth Gaussian noise exposure. Conventional methods were used to measure energy spectra and exposure levels. Measures of permanent threshold shift showed significant differences between the complex noise exposures and the Gaussian exposure. An application of frequency domain kurtosis [R. F. Dwyer, IEEE J. Oceanic Eng. OE-9, 85–92 (1984)] emphasized the region of the noise spectrum where audiometric differences were measured. [Work supported by NIOSH.]
Multiconvolution in waveguides with arbitrarily spaced discontinuities.
Authors: Barjau Ana , Cardona Salvador , Keefe Douglas H.
Published: October 2005

The multiconvolution algorithm [Martínez etal., J. Acoust. Soc. Am. 84, 1620–1627 (1988)] used to calculate the impulse response or reflection function of a musical instrument air column has proven to be useful, but it has the limitation that the spacing between discontinuities is constrained to be some multiple of c Δt (for phase velocity c and time step Δt). Two approaches have been devised to remove this limitation. Each time-domain approach calculates the response of an air column, modeled as an arbitrary one-dimensional acoustic waveguide constructed using cylindrical or conical bore segments with viscothermal damping and tone-hole discontinuities. The band-limited discrete-time multiconvolution (BDTM) specifies band-limited discrete-time reflection and transmission functions at each discontinuity. The continuous-time interpolated multiconvolution (CTIM) uses continuous-time convolutions between analytical reflection and transmission functions and discrete-time pressure signals. The arbitrary spacing between discontinuities is accounted for in the BDTM method by multirate discrete-time processing of the response functions, and in the CTIM method by interpolation of the discrete-time pressure signals.
Octave illusion revisited.
Authors: Huang Wenyi , Pastore Richard E. , Hall Michael D.
Published: October 2005

The octave illusion occurs when two tones an octave apart are repetitively presented dichotically in sequence such that when one ear receives the low tone the other ear simultaneously receives the high tone, with each subsequent presentation of the tones switching ear. The illusion is described as perception of a single tone whose location switches from ear to ear and whose pitch switches from one octave to the other in synchrony with the local shift [D. Deutsch, Nature 251, 307–309 (1974)]. The current study investigates various factors that may contribute to the illusion. Initial experiments replicate the illusion, examining temporal parameters critical to streaming and mapping the frequency of the pitches heard in the illusion. Results suggest that subjects hear only small shifts in pitch and lateralized position, with a major factor being fusion of the simultaneously presented stimuli. Later experiments first explored the pitch and location of a single dichotic pair of 400- and 800-Hz tones, then determined the likelihood of fusion for other harmonically related dichotic stimuli. [Work supported by NSF.]
Loudness levels of orchestral instruments.
Authors: Miskiewicz Andrzej , Rakowski Andrzej
Published: October 2005

The loudness levels of nonpercussive orchestral instruments were calculated from 1/3-octave-band sound pressure levels using Zwicker’s method, as well as Stevens’ Mark VI and Mark VII procedures. The sounds measured were scale segments played pianissimo and fortissimo in various pitch registers. Calculated for bowed instruments, the bassoon, and the oboe, the loudness of scales performed at a constant playing level is nearly invariant in different pitch registers. In contrast, for the flute, clarinet, and brass instruments, the loudness level markedly increases with increases in pitch. Zwicker’s method generally yields higher values of loudness level than both of Stevens’ procedures. The differences between Zwicker’s and Stevens’ phons are more pronounced in the low-pitch registers than in the higher ones. Moreover, due to specific spectral characteristics of musical sounds, for most instruments the dynamic range of loudness predicted by Stevens’ procedures is larger than the corresponding range predicted by Zwicker’s method. [Research supported in part by NIH Grant No. R01NS07270.]
Determination of musical meter using the method of autocorrelation.
Authors: Brown Judith C.
Published: October 2005

The melodic lines of examples of compositions from the baroque, classical, romantic, and contemporary periods have been studied in order to determine the musical meter by computer calculation. The method of autocorrelation is appropriate for this calculation since it is a measure of the frequency of occurrence of events following an event at time zero. If a greater frequency of events occurs on the downbeat of a measure as predicted by Palmer and Krumhansl [‘‘Mental Representations for Musical Meter,’’ J. Exptl. Psychol.: Human Percept. Perform. 16, 728–741 (1990)], then a peak in the autocorrelation function should indicate the time for a single measure. The results of these calculations indicate that computer determination of tempo is quite feasible. Autocorrelation results will be presented in graphical form.