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Journal of the Acoustical Society of America

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Jul 1979

Volume 66, Issue 1, pp. 1-342

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Signature information in the song of the humpback whale

Gordon W. Hafner, C. Lee Hamilton, William W. Steiner, Thomas J. Thompson, and Howard E. Winn

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 1-6 (1979); (6 pages) | Cited 2 times

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This report tests the hypothesis that individual humpback whales (Megaptera novaeangliae) can be recognized and discriminated from other individuals on the basis of the ’’cry’’ vocalization. Multivariate discriminant analyses, based on six measurable variables, were used to examine intra‐ and interindividual differences in the ’’cries’’ from several individuals. Cries between themes of one song are very different, whereas those between songs of one individual are similar. Results show a high degree of discriminating power between individual animals. Thus, signature information is potentially available from ’’cries’’ within songs, despite common song formats for all calling animals on a given bank. The statistical techniques used will be of great value in animal vocalization studies.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms

Sound production by workers facing the queen in Vespa orientalis (Hymenoptera, Vespinae): Frequency and amplitude auto and cross correlations

Jacob S. Ishay and Yosef Hochberg

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 7-11 (1979); (5 pages)

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In nests of Vespa orientalis, sounds are produced both by the larvae (hunger signal) and the adults. Adult workers mainly produce solid borne sounds by tapping the abdomen tip against the rim of the comb. Among these distinct series of tapping sounds is that produced by one or several workers facing the queen as she rests between oviposition sessions. Statistical analysis of 25 series of such taps shows that consecutive taps in a given series tend to be associated in one of the following combinations: (a) much frequency autoassociation, and little amplitude autoassociation; (b) much amplitude autoassociation. It seems that in (a), the tapping is executed in a manner resembling radio frequency modulation (FM), while in (b) it resembles radio amplitude modulation (AM).
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms

Children’s understanding of monosyllabic nouns in quiet and in noise

Lois L. Elliott, Suzanne Connors, Elaine Kille, Susan Levin, Karlene Ball, and Debra Katz

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 12-21 (1979); (10 pages) | Cited 10 times

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A four‐alternative, forced choice adaptive procedure was used to measure the lowest intensity at which children could identify monosyllabic nouns that had been standardized to be understandable (at comfortable listening levels) to inner city, 3‐year‐old children. Results showed no age‐related performance changes when the words were presented against a 12‐talker babble or against filtered noise. In quiet, however, performance improved between the ages of 5 and 10 years. Performance of children with learning problems was poorer than performance of children achieving normal school progress, even though clinical measures of auditory sensitivity showed no differences. Results are discussed in terms of ’’semantic closure’’ skills of children.
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43.70.Dn Disordered speech
43.71.Gv Measures of speech perception (intelligibility and quality)
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation

Effects of small room reverberation upon the recognition of some consonant features

Stanley A. Gelfand and Shlomo Silman

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 22-29 (1979); (8 pages) | Cited 4 times

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The effects of small room reverberation (T=0.8 s) upon phoneme recognition was studied for normal listeners. Recognition performance was significantly poorer under reverberation than in quiet, and poorer in the final position of words than initially. Relative information transmission under reverberation was poorest for place of articulation, and for stop and frication consonants; whereas sibilance, duration, and semivowel information were barely affected. The findings suggest that small room reverberation affects phoneme recognition in much the same way as a speech‐shaped masking noise. In some cases, the error distributions reflect the limited response alternatives imposed by the real word recognition test.
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43.71.Gv Measures of speech perception (intelligibility and quality)
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.70.Dn Disordered speech
43.72.-p Speech processing and communication systems

Relationship between adaptation and the percept and transformations of stop consonant voicing: Effects of the number of repetitions and intensity of adaptors

Ralph N. Ohde and Donald J. Sharf

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 30-45 (1979); (16 pages) | Cited 1 time

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Important issues in selective adaptation research concern the relative contribution of response related (perceptual) and stimulus related (acoustic) effects of the adaptor in the adaptive process. Two response related issues pertain to the effects of the adaptor percept and verbal transformations on adaptation. This investigation systematically examined perceptual and acoustic contributions of the adaptor on the adaptation of the voicing feature. Subjects rated the degree of voicing/voicelessness of end‐point VOT adaptors, i.e., 5‐ and 55‐ms VOT, and an acoustically neutral adaptor, i.e., 25‐ms VOT, during periods of repetitions. The number of adaptor repetitions during each of ten trials was either 5, 32, or 95, and the intensity of the adapting stimulus was either 50, 70, or 90 dB SPL. The major findings were as follows: (1) No significant correlations were found between ratings of voicing percept of the adaptor and magnitude of boundary shift; (2) Increases in repetitions and relative intensity level of end‐point adaptors produced significantly greater phonetic boundary shifts and generally greater affects on ratings of test stimuli; and (3) The end‐point adaptors produced significant shifts in rating of boundary and nonboundary stimuli. The findings indicate that neither the adaptor percept or verbal transformations affected the magnitude of adaptation. These results and those for acoustic parameters strongly suggest an acoustic as opposed to a phonetic basis of adaptation of the voicing feature. Furthermore, the effects of end‐point adaptors on boundary and nonboundary stimuli support the generalized change in feature sensitivity assumed by a fatigue model of adaptation.
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43.70.Dn Disordered speech
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation

Auditory versus phonetic accounts of observed confusions between consonant phonemes

Sigfrid D. Soli and Phipps Arabie

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 46-59 (1979); (14 pages) | Cited 4 times

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The utility of phonetic features versus acoustic properties for describing perceptual relations among speech sounds was evaluated with a multidimensional scaling analysis of Miller and Nicely’s [J. Acoust. Soc. Am. 27, 338–352 (1955)] consonant confusions data. The indscal method and program were employed with the original data log transformed to enhance consistency with the linear indscal model. A four‐dimensional solution accounted for 69% of the variance and was best characterized in terms of acoustic properties of the speech signal, viz., temporal relationship of periodicity and burst onset, shape of voiced first formant transition, shape of voiced second formant transition, and amount of initial spectral dispersion, rather than in terms of phonetic features. The amplitude and spectral location of acoustic energy specifying each perceptual dimension were found to determine a dimension’s perceptual effect as the signal was degraded by masking noise and bandpass filtering. Consequently, the perceptual bases of identification confusions between pairs of syllables were characterized in terms of the shared acoustic properties which remained salient in the degraded speech. Implications of these findings for feature‐based accounts of perceptual relationships between phonemes are considered.
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43.70.Dn Disordered speech
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation

A theoretical study of the effects of various laryngeal configurations on the acoustics of phonation

Ingo R. Titze and David T. Talkin

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 60-74 (1979); (15 pages) | Cited 15 times

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Simulation of glottal volume flow and vocal fold tissue movement was accomplished by numerical solution of a time‐dependent boundary value problem, in which nonuniform, orthotropic, linear, incompressible vocal fold tissue media were surrounded by irregularly shaped boundaries, which were either fixed or subject to aerodynamic stresses. Spatial nonuniformity of the tissues was of the layered type, including a mucosal layer, a ligamental layer, and muscular layers. Orthotropy was required to stabilized the vocal folds longitudinally and to accomodate large variations in muscular stress. Incompressibility and vertical motions at the golttis played an important role in producing and sustaining phonation. A nominal configuration for male fundamental speaking pitches was selected, and the regulation of fundamental frequency, intensity, average volume flow, and vocal efficiency was investigated in terms of variations around this nominal configuration. Parameters which were varied consisted of geometrical factors such as length, thickness, and depth, factors for shaping the glottis, as well as tissue elasticities, tissue viscosities, and subglottal pressure. Since nonlinear stress–strain properties were not included, subglottal pressure did not produce a pronounced effect upon fundamental frequency under these somewhat idealized conditions. F0 rasing correlated strongly with increased tension in the ligament, and somewhat with increasing tension in the vocalis. F0 lowering correlated with increase in vocal fold length when the tensions were held constant, but not with increase in vocal fold thickness. Vocal intensity and efficiency are shown to have local maxima as the configurational parameters are varied one at a time. It appears that oral acoustic power output and vocal efficiency can be maximized by proper adjustments of longitudinal tension of nonmuscular (mucosal and ligamental) tissue layers in relation to muscular layers. Quantitative verification of the ’’body‐cover’’ theory is therefore suggested, and several further implications with regard to control of the human larynx are considered.
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43.70.Bk Models and theories of speech production

Individual differences in the perception of dichotic chords

R. Efron, E. W. Yund, and P. L. Divenyi

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 75-86 (1979); (12 pages)

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A new method was employed to measure the changes in the strength of ear dominance in the perception of dichotic chords as a function of stimulus intensity. The results of the first experiment, where the right and left tones were of equal intensity, revealed striking individual differences in the way the ear dominance of five subjects changed as the intensity of the chords was varied over a 60–dB range—no two subjects exhibiting the same pattern of behavior. Since, within the context of the model of Yund and Efron [J. Acoust. Soc. Am. 62, 607–617 (1977)] these individual differences could result from right–left asymmetries in the subject’s intensity‐response (I‐R) transduction mechanisms, a second experiment was performed in which the two tones had different intensities. From the results of the second experiment the shape of the I‐R function for each ear could be computed. Using these I‐R functions as parameters, the model accurately predicted the idiosyncratic changes of ear dominance observed in the first experiment. The right‐left asymmetries in the I‐R functions also account for previously reported idiosyncratic changes in ear dominance as a function of the frequency difference between the two tones of the dichotic chord.
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43.66.Hg Pitch
43.66.Rq Dichotic listening
43.66.Ba Models and theories of auditory processes

Musical pitch of two‐tone complexes and predictions by modern pitch theories

A. J. M. Houtsma

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 87-99 (1979); (13 pages) | Cited 4 times

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Most studies of the musical pitch of harmonic tone complexes have utilized signals comprising two or more successive harmonics. The present study provides systematic data on melodic interval recognition by three musically experienced subjects with sounds whose missing fundamentals were represented by two nonsuccessive harmonics nf0,(n+m) f0, delivered to separate ears. Data were obtained in the ranges 1?n?9, 2?m?4, and 200 Hz ?f0?1000 Hz. The data are interpreted in the light of three theories, the ’’optimum processor theory,’’ the ’’virtual pitch theory,’’ and the ’’pattern transformation theory.’’ For each theory, a constraint on performance is proposed based on interference between the ’’analytic’’ and ’’synthetic’’ pitch perception modes. The former is obtained with large spacings between harmonics, where listeners are more likely to perceive harmonics as individual tones, each having their own pitch. This degrades the listener’s ability to hear the fundamental pitch.
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43.66.Ba Models and theories of auditory processes
43.66.Hg Pitch
43.75.-z Music and musical instruments

Tone‐segregation by phase: On the phase sensitivity of the single ear

Michael Kubovy and Ray Jordan

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 100-106 (1979); (7 pages) | Cited 1 time

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A monaural complex tone is synthesized from 12 harmonically related pure tones, played in phase. In each of 12 segments, one of the tones (the target) is played out of phase so that the sequence of targets is increasing or decreasing in frequency. If the target is at least 30° out of phase, the targets are perceptually segregated. This tone‐segregation by phase raises doubts concerning several current theories of pitch perception. The phenomenon is conjectured to be caused by the ear’s nonlinear compressive transfer characteristic or by a temporal analysis of the stimulus.
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43.66.Nm Phase effects
43.66.Hg Pitch
43.66.Lj Perceptual effects of sound

Partial masking in the monkey: Effect of masker bandwidth and masker band spacing

David B. Moody

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 107-114 (1979); (8 pages)

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By means of a behavioral procedure in which equal response latency to tone onset was used to derive loudness matches, differential effects of masker spectral composition on loudness growth were determined using Old World monkeys as subjects. The maskers ranged from wide‐band noise to pure tones and included noise bands separated on the frequency continuum by notches. In two of the determinations in which masker bandwidth was varied, there was a clear suggestion that loudness increased more rapidly as masker bandwidth decreased. In the remaining three determinations, there was no evidence of a bandwidth effect. In five of six determinations, in which the separation between masking bands was a parameter, loudness increased somewhat more rapidly in the presence of a wide‐separation masker. These results suggest that, although spread of excitation in the cochlea may contribute to the growth of loudness, its role may be less significant than has generally been assumed. Data are also presented which relate the rate at which masked tones increase in loudness to the amount of the threshold shift.
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43.66.Gf Detection and discrimination of sound by animals
43.66.Cb Loudness, absolute threshold
43.66.Dc Masking

Discrimination of uniform spectrum pulse sequences

Irwin Pollack

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 115-122 (1979); (8 pages)

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Random polarity‐modulated sequences were produced with a uniform short‐term spectrum over defined sampling intervals by a method described by Pierce, Lipes, and Cheetham [J. Acoust. Soc. Am. 61, 1609–1621 (1977)]. These are identified as PLC sequences. By contast, unconstrained random polarity‐modulated pulse trains with a constant interpulse interval may depart from a short‐term uniform spectrum. It is shown that listeners can clearly discriminate between PLC sequences and unconstrained random sequences, and can discriminate among different PLC sequences. This discrimination is more nearly related to the statistical redundancy of the PLC sequences than to their run‐length distribution. Such discrimination is relatively resistant to moderate degrees of temporal jitter and is obtained with other forms of information coding. Discrimination of PLC sequences is presumably based upon phase information.
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43.66.Nm Phase effects
43.66.Jh Timbre, timbre in musical acoustics
43.66.Fe Discrimination: intensity and frequency
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music

Cochlear macromechanics: Time domain solutions

J. B. Allen and M. M. Sondhi

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 123-132 (1979); (10 pages) | Cited 11 times

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In this paper we report on a new method of solving a previous derived, two‐dimensional model, integral equation for basilar membrane (BM) motion. The method uses a recursive algorithm for the solution of an initial‐value problem in the time domain, combined with a fast Fourier transform (FFT) convolution in the space domain at each time step. Thus, the method capitalizes on the high speed and accuracy of the FFT yet allows the BM to have nonlinear mechanical properties. Using the new method we compute (linear) solutions for various choices of model parameters and compare the results to the experimental measurements of Rhode. [J. Acoust. Soc. Am. 49, 1218–1231 (1971)]. We also demonstrate the effect of including longitudinal stiffness along the BM and conclude that it is useful in matching the high‐frequency slope as measured by Rhode.
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43.64.Bt Models and theories of the auditory system
43.64.Kc Cochlear mechanics

The development of middle‐ear admittance in the hamster

Evan M. Relkin, James C. Saunders, and Dan F. Konkle

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 133-139 (1979); (7 pages) | Cited 1 time

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A high‐frequency admittance meter was developed and used to study the maturation of physiological function in the middle ear of neonatal golden hamsters (Mesocricetus auratus). The middle‐ear input admittance in the frequency range of 0.8–1.8 kHz was measured in animals ranging in age from 6 to 69 days postpartum. Admittance magnitude was found to increase steadily with age, beginning on day 16, to asymptotic values at each test frequency. There were no obvious differences in admittance growth rates within the range of frequencies tested. However, an analysis of the slopes of the admittance magnitude frequency response curves revealed an increase from 4.6 dB/octave for animals 25 days old or younger, to 6.3 dB/octave for all older animals. This difference between younger and older subjects indicates that the development of the middle ear in the golden hamster is more complex than a simple increase in pure compliance.
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43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex
43.64.Tk Physiology of sound generation and detection by animals
43.64.Yp Instruments and methods

A sonar target recognition experiment

Paul Chestnut, Helen Landsman, and Robert W. Floyd

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 140-147 (1979); (8 pages) | Cited 3 times

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This paper presents results of an experiment to determine the feasibility of an active sonar target recognition system. Echo data were obtained from 16 targets of maximum dimension 12 in., submerged in a salt water pool. The target frequency responses in the 15–45‐kHz band were used to characterize the targets. The information in the frequency response was extracted in two ways: (1) by calculating the energy in a bank of filters, and (2) by modeling the frequency response as an all‐pole filter. Pattern recognition techniques were applied to define and test the two recognition methods. The results show that target recognition is feasible with either of the methods tested. One hundred percent correct recognition is achieved with 15 parameters when no noise is added to the test echoes. If white noise is added to the test echoes, accuracy is well above 90%, provided the signal‐to‐noise ratio is at least 5 dB.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Vh Active sonar systems

Intercomparisons of laboratory determinations of airborne sound transmission loss

Robert E. Jones

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 148-164 (1979); (17 pages) | Cited 6 times

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An analysis of transmission loss (TL) data from seven north american laboratories was organized by ASTM Subcommittee E33.05 to study ASTM E 90 accuracy performance for single‐ and double‐panel partitions. Several mass law expressions are reviewed and compared with TL data from seven laboratories for four different limp‐mass panel materials. It is noted that the laboratory TL data are not as linear with frequency as generally assumed, and examples are found where TL variation from mass law exceeds that suggested by E 90 precision requirements. In addition, an interlaboratory difference of 2 dB was found for some laboratories. For double‐panel walls, TL data from two laboratories for similar constructions (STC ≳50) showed unexpectedly large variation in TL (up to eight points) and in STC (six points). Using double‐panel theory, these TL differences are explained on the basis of interlaboratory differences in mass law and flanking (perhaps due to the test frame liners). A TL performance test series is illustrated with recent data from two laboratories and suggested as a basis for improving laboratory TL accuracy.
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43.55.Rg Sound transmission through walls and through ducts: theory and measurement

Invertibility of a room impulse response

Stephen T. Neely and J. B. Allen

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 165-169 (1979); (5 pages) | Cited 10 times

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When a conversation takes place inside a room, the acoustic speech signal is distorted by wall reflections. The room’s effect on this signal can be characterized by a room impulse response. If the impulse response happens to be minimum phase, it can easily be inverted. Synthetic room impulse responses were generated using a point image method to solve for wall reflections. A Nyquist plot was used to determine whether a given impulse response was minimum phase. Certain synthetic room impulse responses were found to be minimum phase when the initial delay was removed. A minimum phase inverse filter was successfully used to remove the effect of a room impulse response on a speech signal.
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43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.55.Cs Stationary response of rooms to noise; spatial statistics of room response; random testing

Temporary threshold shift from transportation noise

Michinori Kabuto and Shosuke Suzuki

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 170-175 (1979); (6 pages)

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Temporary threshold shifts (TTS), induced by recordings of aircraft noise, road traffic noise, and interior railroad car noise, were examined to estimate the auditory effects of these typical environmental noises. The aircraft noise used was of a Boeing 747 landing, recorded adjacent to the end of a runway. Six hours of binaural exposure to the noise, presented every 2 min at a maximum A‐weighted level of 97 dB (slow response), developed a TTS2 at 4 kHz of 1.0±2.7 (SD) dB as the mean value for the 57 better ears of 19 subjects on three successive days. The road traffic noise was recorded on a road where traffic volume was 49.5 (26.8 heavy) vehicles per min, and the interior railroad car noise was in a car commonly utilized for commuting. These two noises, reproduced with duty cycles of 4 min 7 s and 3 min 4 s, respectively, induced, after 6 h of exposure, a TTS0.5 at 1.5 kHz and a TTS2 at 4 kHz of almost the same degree at each sound level (A weighted) of 75, 85, and 90 dB, in L50. The TTS0.5 were 0.5, 2 and 3 dB, and the TTS2 were −0.5, 3.5, and 5.5 dB, on the average, for the better ears of three to four persons, which indicates especially that 75 dB for the road traffic noise and 70 dB for the interior railroad car noise are the maximum sound levels which may fail to develop significant TTS even at 4 kHz. The present results lead to the conclusion that affected populations may have TTS induced by road traffic noise but that little effect is likely due to aircraft noise or interior railroad car noise.
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43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
43.66.Ed Auditory fatigue, temporary threshold shift
43.50.Qp Effects of noise on man and society

A model for the fatigue in elastic materials with frequency independent Q

Michele Caputo

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 176-179 (1979); (4 pages)

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The phenomenon of the fatigue in elastic materials is represented by introducing a derivative of real order in the stress–strain relation. It is found that this phenomenon occurs when aγ/ηD (Q is the specific dissipation, η the elastic parameter, ? the yield stress, D the maximum amplitude of the cyclic strain applied with period 4a) is near the critical value 1+0.113/Q. This model allows also to estimate the number of cycles which would give the fatique as function of the maximum strain applied and of its frequency.
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43.40.Dx Vibrations of membranes and plates
46.35.+z Viscoelasticity, plasticity, viscoplasticity
43.40.At Experimental and theoretical studies of vibrating systems

Transverse vibrations of circular plates having nonuniform edge constraints

A. W. Leissa, P. A. A. Laura, and R.H. Gutierrez

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 180-184 (1979); (5 pages) | Cited 2 times

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The free vibrations of circular plates having flexible edge supports have been studied by several researchers for the restricted case when the supports are represented by springs having constant stiffness. In the present paper a general method is presented for dealing with supports having translational and rotational flexibilities which vary in an arbitrary manner around the boundary. It is shown that the varying stiffnesses can be represented as accurately as desired by expanding them into trigonometric series in the polar angle. The exact solution in polar coordinates of the differential equation of motion for the plate is then substituted into the elastic boundary conditions. The resulting infinite characteristic determinant is solved by successive truncation. As an example the case of a plate having a simply supported edge (infinite translational stiffness) with rotational stiffness varying according to L0+L1 cos ϑ (L0 and L1 being constants) is considered. Numerical results are obtained by the method described above and also by using the Ritz method with functions which approximate both the differential equation and the boundary conditions.
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43.40.Dx Vibrations of membranes and plates

Vibrations of a plate with an elastic constraint of eccentric circular part

Kosuke Nagaya

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 185-191 (1979); (7 pages)

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In this paper, a method for solving vibration problems of a viscoelastic plate having an eccentric circular constraint is presented. The frequency equation in a complex form for the plate with arbitrary shape is obtained. Numerical calculations are carried out for two cases of a circular plate with an eccentric circular stepped surface and a circular plate on an eccentric elastic foundation. The nondimensional natural frequencies and the logarithmic decrements are given for these plates.
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43.40.Dx Vibrations of membranes and plates
43.40.At Experimental and theoretical studies of vibrating systems

Thickness‐shear vibrations of a beveled AT‐cut quartz plate

Bikash K. Sinha and Daniel S. Stevens

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 192-196 (1979); (5 pages)

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Thickness‐shear vibration modes of a beveled AT‐cut quartz plate have been analyzed from an equivalent three‐dimensional equation of motion. This equation has recently been applied in the analysis of plano‐convex contoured quartz crystal resonators by Tiersten and Smythe, and has been derived from the dispersion relation obtained in the course of an investigation on overtone modes of coupled thickness–shear and thickness–twist vibrations of trapped energy resonators with rectangular electrodes. Calculations based on the analysis have been shown to have excellent agreement with experimental results. The analysis accounts for the anisotropy, piezoelectricity, and mass loading effects due to the electrodes. The solution for a beveled quartz strip is expressed in terms of Bessel functions of the order ±1/3, and the eigenfrequencies are obtained for harmonic thickness and anharmonic lateral overtones for a given bevel angle and thickness‐to‐length ratio of the linearly tapered crystal strip. Both the clamped and free‐edge boundary conditions are considered.
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43.40.Dx Vibrations of membranes and plates
43.38.Fx Piezoelectric and ferroelectric transducers

A theory of bubbly liquids

Douglas S. Drumheller and A. Bedford

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 197-208 (1979); (12 pages) | Cited 4 times

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A theory of bubbly liquids is developed in which the liquid and the bubbles are treated as separate continua. A variational procedure is used to obtain the equations of motion. The theory is linearized and applied to plane harmonic wave propagation. The dispersion and attenuation solutions are compared with experimental data and with other theoretical predictions. The theory is reduced to single continuum form, and results of previous single continuum theories are recovered.
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43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.20.Bi Mathematical theory of wave propagation

Synthetic aperture sonar in turbulent media

Osamu Ikeda, Takuso Sato, and Hajime Ohshima

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 209-218 (1979); (10 pages)

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A method of synthetic aperture sonar imaging that is effective even in turbulent media is proposed. Signals received at a fixed point on a scanning plane are used as reference signals, and the averaging effect is applied in the process of aperture synthesis to obtain stable images within the same scanning time as conventional methods. The principle and some considerations about the quality of the obtained images are shown, and typical examples derived by computer simulation are given. The results show the effectiveness of the method, and suggest that temporal and spatial correlation lengths of turbulence are the principal factors that dominate the effectiveness.
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43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Vh Active sonar systems

Inhomogeneous waves and the plane‐wave reflection coefficient

George V. Frisk

J. Acoust. Soc. Am. Volume 66, Issue 1, pp. 219-234 (1979); (16 pages)

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The importance of knowledge of the plane‐wave reflection coefficient R for a horizontally stratified medium at complex angles of incidence ϑ=π/2−iα (α≳0) is established. It is shown that for a point source, when the combined source/receiver height is less than one‐quarter wavelength, these inhomogeneous plane waves can make significant contributions to the reflected field. But irrespective of source/receiver height, they are important when normal modes are excited in slow speed regions of the bottom via inhomogeneous–pure wave conversion, thus giving rise to poles in the reflection coefficient. The theory of inhomogeneous plane‐wave reflection is examined within the context of conservation of energy, and an expression for the intensity of these waves is derived. It is shown that although ‖R‖ is bounded by unity for real incident angles, it can be unbounded for complex angles without violation of energy conservation. A general asymptotic result for R for large horizontal wavenumber is also derived. The computation of R for inhomogeneous waves is illustrated for three canonical bottom examples: (a) impenetrable, (b) isovelocity fluid, and (c) isovelocity fluid layer overlying an isovelocity fluid half‐space.
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43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.30.Bp Normal mode propagation of sound in water
43.20.Fn Scattering of acoustic waves
43.20.Ks Standing waves, resonance, normal modes
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