bluuebunny/crossref_metadata_2025 huggingface dataset:
Discriminant analysis of a technical auditory representation of voiced stop consonants
Authors: Benson Peter , Osman Alan
Published: October 2005

Chen et el. [J. Acoust. Soc. Am. Suppl. 1 67, S38 (1980)] present results to show that VOT and vowel formants for speech articulated over a clear channel are less distinct than those over a noisy channel. An analogous experiment is reported here in which the discriminability of stop consonant [b d g] bursts are compared when articulated in CVC words spoken over a clear and a noisy channel. Ten examples of each consonant before each of four point vowels [i a u] were produced by two talkers. The bursts were digitized and transformed into 19 critical band energies [Schroeder et al., J. Acoust, Soc. Am. 66 (1647–1652 (1979)], as a technical approximation to the auditory representation. Multiple step-wise discriminant analysis showed that consonants were well separated and that discriminant functions for the clear channel better discriminated stops from the noisy channel than vice versa. This agrees with Chen et al. and speaks to the utility of the technical auditory representation and of normally articulated speech for speech templates.
An efficient method for testing large vocabulary automatic speech recognition systems
Authors: Eukel Brian W.
Published: October 2005

The performance of automatic speech recognition systems is commonly measured by using large quantities of natural speech as a benchmark. For recognizers which accept large vocabularies, or when many alternative vocabularies are of interest, this method requires an unreasonably large natural speech corpus. Synthetic speech which incorporates variations in pronunciation is an alternative in these cases. This approach was used to evaluate the performance of a speaker trained, isolated word speech recognition system [H. Murveit, M. Lowy, and R. W. Brodersen, J. Acoust. Soc. Am. Suppl. 1 69, S8 (1981)]. Each word to be recognized was modeled as a sequence of segments with each segment being variable length and having a uniform spectrum with added noise. A few tokens of natural speech were used to evaluate the parameters of the model. The model was then used to produce synthetic tokens for testing the recognizer. Good correlation was obtained between the confusion matrices for synthetic and natural speech when recognized. [Work supported in part by DARPA.]
Issues and answers in evaluation of automatic speech recognizers
Authors: Baker Janet M.
Published: October 2005

An extensive comparison of commercially available automatic speech recognition systems revealed a wide range of performance characteristics. On an isolated word, speaker dependent database, the percentage of errors (i.e., 100% − correct recognition%) ranged over two orders of magnitude for the 10 210 utterances tested. The vocabulary consisted of 11 words (the 10 digits plus “oh”) collected from five males and five females in a moderate office-noise environment. Simultaneous recordings were made with headset and table microphones. Every attempt was made to assure that the systems tested were operating optimally, often with vendor cooperation. Although all systems performed better with data recorded from the headset microphone than with the table microphone, the amount of degradation was not uniform across systems. Special problems and solutions for performing these tests will be discussed.
Interdisciplinary contributions to the study of annoyance Chairman's introduction
Authors: Burgess John C.
Published: October 2005

Much of the literature on community noise concerns attempts to correlate measured characteristics of noise with reaction to that noise evaluated from personal surveys. The purpose of this special session is to focus instead on why people react as they do. The special concerns are identification, examination, and measurement of the subjective variables which influence human reaction to sound. Emphasis is on annoyance and the underlying factors to which people react. The three invited papers present methods, viewpoints, and evidence from the points of view of noise control, speech communications, and psychological acoustics. Particularly intriguing is the idea that annoyance is the inverse of preference.
Modeling the perception of sound
Authors: McDermott Barbara J.
Published: October 2005

Characterizing the subjective effects of sound is similar to the problems of characterizing sound itself. Since both are functions of several variables, the values of each variable must be found to evaluate the significance of changes. The wave motion model of sound enables us to express the variability in the nature of sound as a function of its independent variables with great mathematical precision. Similar accuracy in measuring the perception of sound cannot be achieved without a model that expresses the variables of perception and their interrelationships. Methods for studying the variables of perception have been, and are being, developed. The application of these techniques to subjective judgments of sound is currently producing information about the variables of sound perception and their relation to the variables of sound itself in the realm of speech. From this information, a model for combining the variables to predict speech preference is being derived. These methods have not been applied to the problem of noise perception. However, if one considers annoyance as the opposite of preference, the techniques are directly applicable to the problem of characterizing the perception of noise.
Problems and methods in judgments of perceived sound quality
Authors: Gabrielsson Alf
Published: October 2005

The perceived sound quality of any auditory stimulus (music, speech, noise) may be expressed in terms of overall evaluations as well as in terms of specific perceptual qualities. Examples of the former are variables as pleasantness, annoyance, and fidelity, and of the latter perceptual variables as loudness, clarity, sharpness, etc. Studying the relations between overall evaluations and separate variables and their respective relations to the stimulus characteristics may increase the understanding of factors influencing perceived sound quality. The associated methodological problems will be illustrated by examples from research on perceived sound quality of sound-reproducing systems [A. Gabrielsson and H. Sjǒgren, J. Acoust. Soc. Am. 65, 1019–1033 (1979)]. Some possible parallels, as well as dissimilarities, between this research and research on noise-induced annoyance will be discussed.
Measurement and modeling of the vertical directionality of wind-generated ocean ambient noise
Authors: Stockhausen J. H.
Published: October 2005

Investigation of ocean ambient noise vertical directionality has often been performed by measurement and modeling of the vertical spatial correlation function. The wind-generated component that dominates at high frequencies is well described by a mixture of two simple empirical models offered by other investigators. To generalize the description a model was developed for the distant shipping component that dominates at lower frequencies. The vertical spatial correlation function is the Fourier transform of the directional density expressed as the sine of the angle of elevation and all three of the component models used have simple closed form expressions in both spaces. Mixtures of the three models have been used to characterize measurements made at Labrador Sea and North Atlantic sites. Physical modeling of the development of the wind-generated noise directionality revealed considerable sensitivity to bottom reflectivity. Varying bottom, surface, and sound-speed profile parameters, in combination with a single source directionality model, produced a sufficient variety of effects to account for the range of empirical models that fit the data.
Hearistic modeling of horizontal noise directionality
Authors: Bannister R. W.
Published: October 2005

Some aspects of a simple computer model for low-frequency ambient noise prediction are discussed. The shipping component is based on a surface-ship source level proposed by Gray and Greeley [J. Acoust. Soc. Am. 67, 516–522 (1980)]. Surface interference effects are shown to be important and are preserved in a simplified propagation loss algorithm. This allows for range and source depth dependent surface decoupling loss effects which give rise to realistic spectral shaping of low-frequency noise. The shipping component is obtained by adding contributions from ship lanes which are assumed to behave as incoherent line radiators. Consequent properties of horizontal noise directionality are discussed, in particular, the sensitivity to propagation loss, proximity of shipping lanes, and shipping distribution. A semi-empirical relationship is used to predict the wind speed related noise component. This is based on noise measurements in the Kz area extrapolated according to trends implied by theoretical noise mechanisms. Examples of the overall model output are presented and compared with measurement where possible.
Measurement of horizontal anisotropy of shallow water ambient noise due to breaking surf
Authors: Wilson O. B. , Wolf Stephen N.
Published: October 2005

Additional measurements have been made of the horizontal anisotropy of ambient noise in Monterey Bay over a wider variety of sea conditions and range from shore since those reported at the November 1980 meeting. Directionality was measured using a steerable cardioid receiving pattern formed from signals telemetered from dipole and omnidirectional hydrophones suspended from tethered buoys. During heavy surf conditions, anisotropy, defined as the amount by which the shorewardly directed cardioid output exceeds that from the seawardly steered cardioid, as 10 dB at 300 Hz at a range of 9 km from shore and 90-m water depth and is significant from 20 to 700 Hz. Anisotropy is significant at a range of 15 km and water depth of 175 m. During heavy surf, noise levels also increase significantly in the same frequency range at which the anisotropy is evident. The anisotropy effects diminish both in magnitude and frequency range with lower wave height but are still observable during light surf. Evidence is very strong that when wind and surf are high, breaking surf can contribute significantly to ambient noise in fairly deep continental shelf waters. [Supported by the NPS Foundation Research Program and the Naval Sea Systems Command.]
Effects of number of noise events on community response: Results of a reanalysis
Authors: Fields James M.
Published: October 2005

Existing social surveys have been reanalyzed to estimate the effect of the number of noise events on annoyance in residential areas. Though methodological problems may bias existing estimates, the best evidence from the existing data suggests that the effect of a ten-fold increase in numbers of events is equivalent to less than the 10 dB which would be predicted by the equal energy hypothesis in Leq or Ldn. The effects of many noise parameters and study area characteristics have been ignored in the past. The overly simplified annoyance model which has been used includes only noise level and number of noise events. This simple model has provided biased estimates of the relative effect of noise level and number of events in the Second Heathrow and USA Nine Airport (TRACOR) Study. Errors in noise measurements have also biased estimates of the effect of number of noise events. The most serious problems in most surveys have been large sampling variances which are responsible for the unreliable, imprecise estimates of the effect of number. Based on the deficiencies identified in existing surveys, it appears that three major developments must occur before more can be learned about the effect of number: (1) the development of economical noise measurement strategies with known levels of reliability, (2) the identification of a large number of study areas with the noise characteristics required for an efficient study design, and (3) the accumulation of knowledge about the variance of responses between study areas.
Resident annoyance response to aircraft noise events
Authors: Dempsey Thomas K. , Stephens David G.
Published: October 2005

A study of the annoyance response of airport community residents to the noise of aircraft takeoff and landing operations was conducted in Salt Lake City, Utah in the fall of 1980. The objective of the study was to develop a single-event, dose-response relationship for aircraft noise and determine the dependence of the relationship on variables such as aircraft type, time of day, and ambient noise level. The test at each home involved measuring indoor and outdoor noise for each flyover while simultaneously obtaining annoyance reactions from the residents. These tests were conducted at three different times of the day (morning, afternoon, and evening) to provide information on time-of-day weightings for noise metrics. A total of 101 residents (61 male and 40 female) completed the tests. Outdoor measured A-weighted sound pressure level of the aircraft noise provided the single most accurate prediction of resident annoyance. However, increased accuracy was found by accounting for outdoor ambient noise and house attenuation. Annoyance response prediction was independent of aircraft type. Finally, time-of-day weightings derived from the results of the study, were smaller (≈6 dB) and shifted to the evening period as compared to the standard 10-dB nightime penalty.
Community noise from air cushioned landing craft
Authors: Burke Richard
Published: October 2005

The effect of noise on neighboring communities resulting from operating the U.S. Navy's proposed Air Cushioned Landing Craft (LCAC) at an initial training site is predicted and evaluated in this preliminary impact assessment. Farfield noise levels of two prototype vehicles, each with a maximum gross weight of 160 tons, were measured under various stationary and moving modes at the Naval Coastal Systems Center in Panama City, Florida. These data and appropriate vehicle operating characteristics were entered into NOISEMAP, a noise contour generating computer program which has heretofore only been used in aircraft noise analyses. Four vehicles undertaking a total of 440 annual missions were found to generate a 65-dB DNL contour with an area of only 14 square mile. Nonetheless, single event maximums over 65 dB predicted near residential locations were identified as potential areas of adverse impact on the community. [Work supported by the U.S. Navy.]
Noise exposure around joint-use airports
Authors: Burke Richard
Published: October 2005

Present and future exposure of people to noise from airports in the U.S. which have both civilian and military based aircraft were evaluated. Imposition of civil noise regulations in five increasingly stringent stages results in unmodified military aircraft assuming a greater share of joint-use airport noise exposure. This increased dominance was estimated by grouping 65 airports into five airport classes, obtaining noise contours for average airports in each class, and scaling the results to yield nationwide totals. Population, fleet mix, and operations were held constant. Total population exposed to 65 dB DNL or greater was an estimated 900 000. Considering military and civil operations in isolation, the military contribution to area exposed to 65 dB DNL or greater was about 60% under stage 1 and 90% under stage 5. Greatest marginal benefit occurred between stage 2 (recently enacted) and stage 3 (proposed for 1985). Large airports benefited most from civil regulations. Airports with fighter aircraft contributed 60% to 75% of total noise exposure.
Improved engine core noise prediction procedure
Authors: von Glahn U. H. , Stone J. R. , Groesbeck D. E.
Published: October 2005

The frequency content and noise levels of turbine-type aircraft engine core noise are re-examined as a result of recent static and flight test data. In addition, diagnostic techniques developed within the past year have provided a better understanding of core source noise. On the basis of these new inputs, core noise prediction procedures are re-evaluated and a preliminary update of the procedures is presented.
Broadband sound from wind turbine generators
Authors: Hubbard H. H. , Shepherd K. P. , Grosveld F. W.
Published: October 2005

Sound spectra are characterized for the various types of wind turbine generators. Emphasis is placed on the broadband sound because it is an important component for upwind and downwind horizontal axis machines as well as for vertical axis machines. The various sources of broadband sound are identified and are rank ordered for the MOD-2 machine which has 300-ft-diam blades and is rated at 2.5-MW power output. The main sound sources for the MOD-2 rotor are noted to be the inflow turbulence (30 to 50 Hz) and the interactions of the turbulent boundary layers with the blade trailing edges (800 to 1300 Hz). The MOD-2 rotor radiates in all directions but the distant sound level contours are elongated in the downwind direction due to refraction effects of the wind. [Work supported by the NASA Lewis Research Center and the Department of Energy.]
Methods for state and local governments to use to control noise from construction sites
Authors: Hawley Mones E. , Back Geoffrey G.
Published: October 2005

State and local noise control officials, citizens' groups, construction equipment manufacturers, construction contractors, and unions that represent construction workers were consulted nationally. The investigation was undertaken after it was reasonably clear that in the near future the Federal government is unlikely to issue new regulations controlling the noise levels from construction equipment. The manufacturers reported that the primary impetus for noise reductions came from the need to reduce exposure to occupational noise and from the need for quiet equipment to compete successfully in Europe. The most effective noise control measures are in-use controls. These include hours of operation, operation of equipment with all noise control components in place, location of equipment on the construction site, use of alternate equipment, rerouting of vehicles, property line standards, and operator concern. The marginal cost of adding a construction component to an existing municipal noise control program was calculated. [Work supported in part by U.S. Environmental Protection Agency.]
An improved Kirchhoff formula for scattering loss at low grazing angles
Authors: Chapman D. M. F.
Published: October 2005

The plane wave reflection loss due to scattering at rough ocean surface is calculated using a boundary perturbation method involving an integration over the surface wave spectrum. For large correlation lengths the integral reduces to the commonly used Kirchhoff formula, except at low grazing angles. The corresponding normal-mode attenuation coefficients for low-order modes are consequently underestimated by the Kirchhoff formula. Using a Gaussian wave spectrum for convenience, an alternate formula is proposed which is valid for large correlation lengths at low grazing angles or low-order modes.
High-frequency contributions to the SN10 response
Authors: Champlin Craig A. , Laskowski Randy , Owen Jeffrey H.
Published: October 2005

The slow negative brainstem response (SN10) to tone-burst stimuli has been used to assess peripheral auditory function. When basilar membrane displacement and physiological tuning curves are considered, basal contributions of frequencies above the stimulus frequency are suggested. This study examined the SN10 in response to monaural stimulation at the center frequencies of 1000 and 2000 Hz. Signals were presented at 50 dB nHL. Two conditions were utilized: (1) SN10 responses were obtained at the beginning and end of each session without masking, (2) A series of ipsilaterally presented high-pass noise masking conditions were administered between the nonmasking conditions. The slope of the filter was also manipulated. The amplitude, latency, and morphology of the SN10 were evaluated for each condition.
Electrophysiological responses of hearing-impaired subjects to speech stimuli
Authors: Polen Samuel B. , Greenwood R. Patrick , Yoneda Carol
Published: October 2005

It has been demonstrated [Polen et al. (1981)] that certain unique electrophysiological phenomena may occur in response to the presentation of target phonemes within an orienting response paradigm. Subsequent to these findings, it was questioned whether such responses would be altered due to the presence of hearing loss. This study investigated the characteristics of late components of the averaged electrophysiological response to speech stimuli for sensorineural hearing impaired subjects. Evoked potentials were obtained in response to stimuli presented within an orienting response paradigm. The stimuli consisted of target phonemes interspersed at random intervals in the “background” of a repeating, contrastive phoneme. The averaged waveforms obtained were further subjected to Fourier analysis, resulting in discrete energy spectra of from 0 to 20 Hz. It was found that subjects with severe hearing losses in the range of 1.5–8 kHz responded with greatest energy in the 8–11 Hz component range, while those with relatively better hearing through 2 kHz tended to demonstrate greater energy for the 1–5 Hz components.
An ear simulator study of resonances in occluded human ear canals
Authors: Gilman Samuel
Published: October 2005

The frequencies at which resonances occur in an occluded ear canal were measured over a range from 100 Hz to 20 kHz using ear simulators (Zwislocki, 1970) and a constant volume displacement source (B&K 4134 microphone operated with zero bias). Three variables were introduced: earmold bore, ear-canal length, and eardrum impedance. Mid-frequency resonance frequencies (1000 to 3000 Hz) were found to be primarily functions of the reactance of the load presented to the source by the occluded simulator. Resonances at frequencies between 9 and 13 kHz were related to ear canal length. Ear canal volume or diameter affected resonances on the basis of their contribution to the input impedance of the simulators. Major resonances also occurred at frequencies related principally to the source-to-eardrum distance (independent of impedance).
Performance of a blanket in the presence of flow
Authors: Maidanik G. , Eisler T. J. , Maga L. J.
Published: October 2005

Over a decade ago a paper by G. Maidanik and W. T. Reader evaluated the performance of a blanket dome [“The Filtering Action of a Blanket Dome,” J. Acoust. Soc. Am. 44, 497–502 (1968)]. A blanket separates the pressure field that forms on the top surface from the corresponding pressure field that is perceived on the bottom surface of the blanket; the surfaces are plane and parallel. The space between the two surfaces is filled uniformly with fluid-like material specified by a density ρb and a speed of sound cb. In the referenced evaluation the ρc-fluid medium occupying the semi-infinite space above the blanket was assumed to be quiescent. Motivated by a recent reanalysis, conducted by A. Dowling and J. Ffowcs-Williams, of the spectral density of the pressure field on a surface beneath a turbulent boundary layer, it was decided to assess the influence of flow on the performance of blankets. [Private communication from Cambridge, England.] The results of the assessment will be reported and discussed. For example, it will be presented that in highly subsonic flows, rigid backings, and the conditions that ρ = ρb and c = cb, a thin blanket may singularly amplify sonic spectral components that lie in the positive direction of flow; no such amplification occurs in components that lie in the opposite direction.
Optical and acoustical measurements of the dynamic tensile strength of water
Authors: Clark Joseph A.
Published: October 2005

Cavitation bubbles produced by propagating acoustic tensile waves in water have recently been directly observed by this researcher and others. However, only changes observed in the acoustic wave forms detected by ceramic or quartz transducers have previously been used as criteria for determining the tensile strength of water and other liquids. In this investigation, the tensile strength of water was determined by directly observing the occurrence of cavitation bubbles produced by transient acoustic pulses. The results were also compared with determinations based on acoustical measurements made with a polymer hydrophone which is known to more accurately measure the form of short duration transient acoustic waves than currently available ceramic or quartz transducers. Implications of these results for medical diagnostic ultrasound equipment will also be discussed. [Research sponsored by ONR.]
Measurement of acoustic intensity in the presence of one-dimensional fluid flow
Authors: Comparin Robert J. , Rapp John R. , Singh Rajendra
Published: October 2005

In this paper we present some results of our analytical and experimental investigation on the measurement of acoustic intensity in the presence of mean fluid flow. This investigation was necessitated by the fact that an acoustic intensity technique with mean fluid flow is not available. Munro and Ingard [J. Acoust. Soc. Am. 65, 1402–1406 (1979)] have, however, developed a formulation for this problem; but no experimental data or verification is given. We have evaluated this formulation with measured data in a duct. Additionally, we have developed two independent formulations for acoustic intensity in a duct with mean fluid flow using two-microphone cross-spectral density method. All of these expressions have been evaluated experimentally for the case of one-dimensional irrotational and isentropic mean fluid flow. Specifically, we were interested in determining the significance of various additive terms to the nonflow acoustic intensity expression. For the Mach number (M) range of 0–0.15, acoustic intensity with flow (If) could be approximated by the following simple expression: If ≃ I0 (1 ± M)2, where I0 is the acoustic intensity without flow. In this paper we will discuss various aspects of this problem and make appropriate recommendations.
Dynamic and static modeling of the Shuttle Orbiter's Thermal Protection System
Authors: Synder R. E.
Published: October 2005

Seventy percent of the surface of the Shuttle Orbiter is covered by a Thermal Protection System, consisting of ceramic tiles bonded to the Orbiter's aluminum skin through a felt pad. The structural evaluation of the tile/pad system is complicated by the nonlinear elastic properties of the pad. This paper describes the dynamic and static analysis methods utilized to model this nonlinear behavior. Comparisons between test and analysis are shown. Vibration tests of individual tiles identified tile response which results from the nonlinearity of the pad. These phenomena include a highly distorted response waveform when the tile/pad system is base-driven dinusoidally and resonant frequencies which are dependent on both steady pre-load and amplitude of the base drive input. The dynamic analysis accounts for the nonlinear stiffening, hysteresis and viscous behavior of the pad material. Material characterization tests of the pad revealed a load displacement nonlinearity which is agravated with repeated load cycles. A nonlinear stress analysis procedure was developed and programmed to permit the calculation of stresses at the tile/pad bondline for an arbitrary pad contiguration.
Baby talk: Acoustic description of infant's comfort-state vocalizations
Authors: Kent Ray D. , Murray Ann
Published: October 2005

Comfort-state vocalizations were recorded from 21 infants, seven at each of the ages of 3, 6, and 9 months. Spectrograms and digital methods were used to determine utterance durations, formant frequencies of vocalic segments, and characteristic features of phonatory behavior. Histograms of utterance durations show that the great majority of utterances had durations of 400 ms or less, although some utterances lasted a second or more. Volcalic utterances had formant frequency ranges of F1 = 0.6–1.4 kHz and F2 = 2.0–3.8 kHz for 3-month-olds, F1 = 0.5–1.7 kHz and F2 = 1.6–3.8 kHz for 6-month-olds, and F1 = 0.5–1.7 kHz and F2 = 1.4–4.1 kHz for 9-month-olds. Thus, the acoustic vowel space increased in both the F1 and F2 dimensions across the three age groups. Mean fundamental frequency was 445 Hz for 3-month-olds, 450 Hz for 6-month-olds, and 415 Hz for 9-month-olds. Laryngeal function varied substantially both within and across utterances, with some phonatory properties either differing greatly from adult speech or rarely if ever appearing in adult speech. Most infants had occasional vocal tremor, the frequency of which (9–21 Hz) was higher than that reported for adults (4–8 Hz). Infant vocalizations often were associated with rapid f0 changes, noise components particularly in the higher frequencies, alternating noise excitation, and biphonation (sudden appearance and disappearance of subharmonics, especially the 12 f0 series). Apparently, the infant drives the larynx to the extremes of its functional ranges, perhaps including nonlinear regions avoided by adults. [Work supported by NIH.]
The spatial sampling problem in electromyographic studies of speech musculature
Authors: Cooper Donald S. , Folkins John F.
Published: October 2005

The general practice of insertion of a single electrode pair per muscle for electromyographic recording raises the question of how representative are the signals obtained. Signals from three bipolar fine wire derivations high, middle, and low in the same palatoglossus muscle of speakers of American English were amplified, rectified, and integrated. The data were analyzed statistically to determine the patterns of similarity among simultaneous signals from different sites in the muscle for a given speaker, and the degree of independence of each signal. The middle signal was most often the best, and the low signal most often the poorest representative of the group of signals. The greatest similarity was found between the high and middle signals; next most similar were the middle and low signals. Similarity between signals varied as a function of the utterance. Nonlinear relations were observed between some signals. In some cases the relationship between two signals varied over time. This variation may be due to change in interelectrode distance during anisometric contraction. [V. Pollack, Med. Biol. Eng. 9, 657–664(1971)], or to recruitment patterns. [Work supported in part by NIDR.]
Procedures for parametric analysis of the calls of nonhuman mammals
Authors: Carterette Edward C. , Shipley Carl , Buchwald Jennifer S.
Published: October 2005

Whoever wishes to describe animal vocalizations is faced with the task of developing a species-specific phonetics. The most difficult part of the task is constructing adequate measures of vocalization. We have designed a system that uses digital computation based on linear prediction technique to quantify a family of parameters of feline calls. The analysis proceeds in two stages. First, a series of general functions that describe different parameters is obtained: pitch period, formant, rms values, harmonic ratio, energy ratio, and formant ratio. The second stage summarizes these functions as sets of descriptive statistics. Because the use of digital computation in analyzing animal cries is quite new, there is no standard approach to this measurement problem. The methods developed here will, we hope, prove useful in the quantitative description of the vocalization of a large number of mammalian species. Also, since these analyses stem from recent research on human speech, they may be useful in the comparative study of vocalizations of humans and other mammals. [Work supported in part by NIH HD-05958.]
Optimization of the transmitting response of a high power transducer in a wide bandwidth by finite element method
Authors: Tocquet B. , Boucher D. , Decarpigny J. N. , Debus J. C.
Published: October 2005

The fundamental mode of a TONPILZ piezoelectric transducer is characterized by a pistonlike deformation highly coupled with the fluid. Towards the upper bandwidth's boundary flapping modes appear, which exhibit important deformations of the head mass and are also coupled with the fluid. These modes can increase the bandwidth if their resonance frequencies and coupling coefficients are well chosen. To improve this choice, we have developed a computer program using the finite element method. In water, fluid elements are used with the pressure as variable. Radiation is expressed on an exterior surface without boundary reflection through use of a suitable impedance. The matrices are assembled following a frontal method and a GUYAN reduction. For its optimization, the head mass is separated from the ceramic stack. This technique reduces drastically core size requirements and computer costs. It makes also designer's work easier. In this paper, we describe the results obtained with a circular head TONPILZ and compared with experimental results.
Analysis and design of a 600 acoustic watt siren for an acoustic agglomeration of submicron particles in gas streams
Authors: Reethof Gerhard , Shane Stephen J.
Published: October 2005

The 600 acoustic watt siren to provide either pure tone or warble tone sound in the frequency range of 1000 to 4000 Hz was designed on the basis of a lumped parameter analytical model using electrical analogies of the acoustical elements. The pressure source, rotor and stator ports, the exponential horn, and the agglomeration chamber are represented. The time varying nature of the porting arrangement is recognized. The power output of the siren as a function of frequency (siren speed), supply pressure and air flow agrees well with the predicted values. Acoustic efficiencies ranging from 25% to 33% were attained. Since axial clearances between rotor and stator were the limiting factors larger sirens contemplated for industrial use are expected to provide higher efficiencies. Thus, overall efficiencies including the compressed air supply system in the vicinity of 27% appear feasible. The siren has operated without breakdown for about 1000 hours.
Axial response of a spherical acoustical reflector
Authors: Cole Lowell D.
Published: October 2005

The axial response of a 3-ft-diam acoustic reflector to an incident sound wave was measured by placing a microphone at different positions along the reflector axis. The measurements, performed in the anechoic room at the National Bureau of Standards, were made at five frequencies from 5 to 35 kHz, and at two source-to-reflector distances. The point of peak response shows some frequency dependence, which contrasts with the frequency-independent (geometrical acoustic) image location predicted by the spherical mirror formula. For comparison, the response pattern is calculated by diffraction theory, assuming normally incident spherical waves.
Tests of causality, linearity, time-translation invariance, and minimum-phase behavior for cochlear-partition response functions
Authors: Koshigoe Shozo , Tubis Arnold
Published: October 2005

Several theoretical and experimental cochlear response functions are tested with respect to the implications of causality (C), linearity (L), time-translation invariance (TTI), and minimum-phase behavior (MPB). We consider, in particular, two-dimensional models (with and without viscoelastic coupling of the basilar membrane and the organ of Corti to the tectoral membrane) and the experimental cochlear response data of Rhode and his coworkers. Both the model results and experimental data are in fair to good accord with C, L, TTI, and MPB. Extensions of the analysis for the case of nonlinear response functions, which are consistent with C and TTI, are briefly discussed. [This work was supported by NSF.]
A numerical treatment of rough surface scattering for the parabolic wave equation
Authors: Dozier Lewis B.
Published: October 2005

Scattering of underwater acoustic signals from real ocean surfaces often does not fit into any of the classical theoretical approaches to the problem. Thus, the need for a numerical approach is clear. A novel method is presented that uses a sequence of conformal mappings to locally flatten successive segments of the surface, which is assumed piecewise linear and frozen in time. Each conformal mapping preserves the elliptic form of the reduced wave equation, so that in each transformed space the parabolic approximation can be made and the solution advanced one range step using the split-step Fourier algorithm. Numerical PERUSE (PE Rough Surface) results for rough surface scattering in surface ducts are analyzed by resolving them in depth into the virtual modes of Labianca [J. Acoust. Soc. Am. 53, 1137–1147 (1973)]. The resulting modal intensities are then plotted as a function of range, and decay rates are estimated for each mode. Comparison with simple Rayleigh theory shows no obvious correlation; it appears that there is significant mode coupling due to the rough surface.
Scattering from a periodic rough surface between a fluid and a solid
Authors: Chuang Shun-Lien , Johnson Richard K.
Published: October 2005

A rigorous theory based on the extended boundary condition method is proposed to solve the problem of diffraction from a fluid/solid interface which has periodic roughness. The extended boundary condition is derived by applying Green's theorem to the total fields and the Green's functions for the periodic surface in the fluid region and the solid region separately. A complete set of basis functions (Fourier series) is then chosen for the expansions of the unknown displacements and the tractions on the surface. The set of integral equations is reduced to simple matrix equations which are solved for the coefficients of the basis functions of the surface fields. The diffraction efficiencies of the incident plane wave from the fluid to the reflected compressional waves and the transmitted compressional and shear waves of different Floquet modes are calculated. Energy conservation is used to check the accuracy of the numerical results. The case of a lossy (viscoelastic) solid is included in the study. For experimental verification, an acrylic block was machined to have a symmetric sawtooth surface profile with a height 0.49 mm and a period 5.08 mm. The scattering from this block immersed in water is measured at 500 kHz. The diffraction efficiencies of different Floquet modes in the water are measured versus angle of incidence. Very good agreement is achieved between the theory and the experiment.
Detailed analysis of bottom reverberation data
Authors: Eller Anthony I.
Published: October 2005

Measurements of bottom reverberation by Mackenzie [K. V. Mackenzie, J. Acoust. Soc. Am. 33, 1498–1504 (1961)] form the basis of a widely used model for bottom reverberation. The smoothed trend of his results is consistent with a general understanding of reverberation, as based on Lambert's law. The present analysis was undertaken to reveal causes of the detailed fluctuations of the reverberation data about the smoothed trend. It was found that interference between direct and surface-reflected paths is the basic cause of fluctuation, but if quantitative agreement with data is to be obtained, then it is necessary to take into account a 3-ft difference between source and receiver depths. A series of comparisons between predictions and data shows the relative influences of various aspects of the experiment on the observed details.
Impulse response methods to evaluate the reflection and transmission of acoustic pulses by viscoelastic plates
Authors: Stepanishen Peter R. , Strozeski Bernard
Published: October 2005

An impulse response and convolution integral method is presented to evaluate the reflection and transmission of acoustic wideband planar pulses by fluid loaded multilayer viscoelastic plates. The reflected and transmitted pressure pulses are expressed as the convolution of the incident pressure pulse with the reflected and transmitted impulse response, respectively. The impulse responses are equivalent to the inverse Fourier transform of the reflection and transmission coefficients which are obtained by transfer matrix techniques for the multiplate configuration of interest. Extensive numerical results are presented to illustrate the main characteristics of the reflected and transmitted pulses which result from an incident pressure pulse impinging onto a plate. Both normal and oblique incidence are considered for single and multilayer plates. The results, which were obtained via the use of FFT methods, illustrates the pulse distortion as a function of plate configuration, plate losses, and angle of incidence.
Estimates of coherence of low-frequency low-grazing angle sound reflected from the sea surface
Authors: Berkson J. M.
Published: October 2005

Sea surface scattering experiments were conducted in which sound from underwater explosives was reflected from the sea surface at grazing angles 5° to 40° and was received by vertically separated sensors of a hydrophone array. The sensor separation varied from l0 to 250 m. The surface-reflected arrivals were isolated and processed to obtain estimates of spatial coherence and reflection-loss spectra for frequencies 20 to 250 Hz. The coherence estimates were obtained as a function of frequency, grazing angle, sensor separation, and bearing for different sea surfaces of low sea state. Simultaneous with the acoustic experiment, ocean wave height time series were measured by three oceanographic data buoys operating in the general region of the experiments. Processing of these data yielded estimates of the ocean wave roughness spectra. Sea surface roughness estimates from the acoustic data were consistent with the measured sea surface roughness. [Work supported by NORDA and Naval Electronic System Command.]
Volume reverberation measurements in the Eastern Caribbean Sea
Authors: Levenson Coleman , Love Richard H. , Wilson Marcia A.
Published: October 2005

Volume reverberation measurements were made utilizing surface-vented explosive sources and an omnidirectional receiver in the Caribbean Sea along the Aves Ridge during winter and summer. Results are presented in the form of scattering strength profiles and column strengths for one-third octave bands between 2 and 20 kHz. Seasonal variations in scattering were found to be small, as were geographical variations both along and across the Aves Ridge. During both seasons diel differences in column strengths of up to 18 dB occurred at frequencies below 5 kHz. Above 10 kHz nighttime column strengths were only several dB higher than daytime values.
Measurements of man-made underwater noise off North Slope, Alaska
Authors: Cummings William C. , Holliday D. Van , Ellison William T.
Published: October 2005

Recordings of man-made underwater noise in the Barrow and Prudhoe areas provided acoustic measurements of helicopters, cranes, detonations, power plants, island building, seismic profiling, off-shore drilling, human movements, unidentified machinery, tugs, and other marine service craft. The recordings, made in winter, spring, and fall, were obtained from under the ice, or from leads, polynyas, or open water at distances from a few meters to about 185 km from the source. Estimated overall source levels varied from 40 to over 200 dB re 1 μPa at 1 m, in the effective bandwidths. Principal acoustic energy occurred in bands falling between 10 Hz and 13 kHz. Among the lowest levels encountered were those from the sounds of oil exploration drilling. The highest were from seismic profiling. Durations of man-made sounds varied from msec (metallic impulses) to continuous (line spectra from engines). In terms of frequency (Hz), duration, and power, many of the measured man-made sounds had the potential for masking underwater animal vocalizations or other acoustic signals. Speculations are made on the possibility of inducing avoidance or even deafness. [Work supported by AEWC, NOAA/OCSEAP.]
Noise disturbance and audibility in pinnipeds
Authors: Schusterman Ronald J. , Moore Patrick W.
Published: October 2005

Individual fitness in all species of pinnipeds depends to a great extent on the transmission and reception of acoustical information transmitted in the hydrosphere as well as in the atmosphere. Major features of sound detection, pitch perception, and sound localization are available for one, or at the most, two individuals belonging to two otariid species and to four phocids. The latter hear higher frequencies under water than to otariids, and the opposite is true for airborne sounds. Masked hearing threshold experiments using center frequencies of, 4, 8, 16, and 32 kHz resulted in critical ratios (in dB) for two northern fur seals, in the order of frequencies given above, of 20, 20, 25, and 27 [P. W. Moore and R. J. Schusterman, J. Acoust. Soc. Am. 64, 587 (1978)] and for two ringed seals they were, respectively, 30, 32, 34, and 35 [J. M. Terhune and K. Ronald, J. Acoust. Soc. Am. 58, 515–516 (1975)]. Field observations suggest that startle or flight reactions to airborne noise habituate at different rates for different species, for different populations and for different groups within a population as a function of age, sex, season, and time of day. Observations of captive northern fur seals suggest that orientation toward airborne sounds may partly be a function of their hearing sensitivity. [Work supported by ONR.]
Masking by gated or continuous noise
Authors: Arguelles Joseph , Bernstein Richard S. , Raab David H.
Published: October 2005

Two experiments were carried out to compare the masking effectiveness of gated and continuous noise. In the first experiment, trained listeners were presented with 100-ms signals (tones or noise). Thresholds were determined using a 2IFC staircase procedure. We confirm the finding of Wier et al. [J. Acoust. Soc. Am. 61, 1298–1300 (1977)] that, for tonal signals, the signal-to-noise ratios are about the same under the two masking modes. Noise signals, on the other hand, are more effectively masked by gated than by continuous noise. In the second experiment, tape-recorded stimuli were presented to two classes of introductory psychology students. The group's correct detections (2IFC) were determined for each of five signal-to-noise ratios. As with practised listeners, the group results show that tones are equally masked by gated and by continuous noise, while noise signals are harder to detect when the presentations are gated.
Phase sensitivity in forward masking
Authors: Shannon Robert V. , Schreiner Christoph
Published: October 2005

Forward-masking functions were obtained using sinusoidal maskers of 300-ms duration followed by a 20-ms test signal at the same frequency. Changing the phase of the test signal relative to the phase of the masker leads to variations of the masking threshold of up to 6 dB. Changes of the gap duration between masker and test tone which correspond to relative phase shifts between masker and test signal result in similar threshold shifts. The phase sensitivity of the forward-masking threshold decreases with increasing gap duration. For gaps longer than about 10 ms no phase effect can be measured. The influence of frequency and masker level on the phase sensitivity will be demonstrated. Implication of these data for the persistence of phase locked information will be discussed. [Work supported by NIH Grant NS-11804 and DFG 228/1.]