bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep-Ocean Ambient-Noise Spectra in the Northwest Atlantic
Authors: Perrone Anthony J.
Published: October 2005

Ambient sea noise was measured from an omnidirectional hydrophone located in the deep-ocean environment. The hydrophone is installed in about 2400 f and is suspended 400 ft above the ocean bottom. The results illustrate the time variability and the correlation of deep open-ocean ambient-noise spectra with simultaneous wind-speed and wave-height measurements recorded during typical winter conditions. Broad-band ambient noise levels were automatically recorded on magnetic tape for 2 min every 2 h. The average value of ambient-noise in 25 logit-filter bands of frequencies ranging from 11 to 2816 Hz was measured for each 2-min sample. Autocorrelations of ambient-noise levels, wind speed, and wave height, as well as cross-correlation of ambient-noise levels with wind speed and wave heights, are presented. The ambient-noise spectra show the superposition of two major noise sources. One noise source is suspected to be distant shipping. This noise source predominates in the frequency range between 17 and 112 Hz and shows noise maxima occurring at 20 and 60 Hz. The other noise source is wind dependent and is observed below 17 and above 112 Hz. The variation in the standard deviation as a function of frequency at low wind speeds is suspected to be the result of the superposition of the two noise sources. The correlation coefficient of wind speed or wave height to sea noise varies as a function of frequency and wind-speed group.
Effect of Pulsed Masking on Selected Speech Materials
Authors: Dirks Donald D. , Wilson Richard H. , Bower Deborah R.
Published: October 2005

Monaural intelligibility functions for spondaic and monosyllabic words and identification functions for synthetic sentences were obtained for 14 experimental conditions of masking by random noise. The noise was presented continuously and interrupted or modulated (−14-dB interburst ratio) at rates of 1, 10, and 100 interruptions per second. The intensity levels of the maskers were 50 and 90 dB SPL. Results demonstrated that (1) masking effectiveness decreased for spondees and sentences as the interruption rate decreased; (2) the greatest release from masking for monosyllabic words was found during the 10-ips condition at favorable S/N ratios; however, at the more unfavorable S/N ratios, greater release from masking was observed during the 1-ips condition; (3) greater release from masking occurred for interrupted than for comparable modulated noise conditions. The possible effects of the interaction between the type of speech material and forward and backward masking during the silent interval between noise bursts is discussed.
Effects of Differing States of Attention on Acoustic Reflex Activity and Temporary Threshold Shift
Authors: Durrant John D. , Shallop Jon K.
Published: October 2005

Temporary threshold shift (TTS) and acoustic reflex activity were observed in 20 normal hearing subjects under several different states of attention. The Zwislocki acoustic bridge (model 3) was used to monitor acoustic reflex activity. Compliance shifts (changes in relative compliance) were measured during exposure of the contralateral ear to a 1000 Hz narrow-band noise presented at 105 dB SPL, and TTS was measured at 1000 Hz for the contralateral ear after approximately 412 min of noise exposure. These measures were taken under three different conditions or modes of attention as defined by task performance: reverie (no task performance, high auditory attention), intelligibility test, and high visual attention (visual-motor task). Also, levels of attention, as operationally defined by levels of task performance, were considered. From the results of this and other investigations it was concluded that there is a so-called central factor involved in acoustic reflex activity although task performance per se, not type of task, is the important factor. However, such a factor in TTS, if observed, is probably an artifact of the type of task performance of the listener.
Time-Domain Measurements of Cochlear Nonlinearities Using Combination Click Stimuli
Authors: Goblick Thomas J. , Pfeiffer Russell R.
Published: October 2005

The interleaving peak structure of poststimulus time (PST) histograms of low-frequency cochlear-nerve-fiber responses to acoustic clicks of both polarities implies that a cochlear neuron is excited by a damped oscillatory waveform, referred to here as a click excitation function (CEF) that is half wave rectified. For a stimulus consisting of two closely spaced clicks, the amplitude and delay of the second click relative to the first click can be adjusted so that one-half cycle of the CEF due to the first click nulls or cancels a particular half-cycle of the other CEF. A null produced in this manner can be detected from the PST histograms of responses of a particular fiber to both polarities of the click-pair stimulus. This nulling technique has been used to study the responses of cochlear nerve fibers to combination click stimuli. Details of these measurements are given, and the interpretation of the results leads to the consideration of two apparently different nonlinear phenomena. These results and the techniques used to obtain them provide a means by which certain constraints on the mechanisms of the peripheral auditory system can be evaluated.
Cochlear Hair-Cell Damage in Guinea Pigs after Exposure to Impulse Noise
Authors: Poche Lynn B. , Stockwell Charles W. , Ades Harlow W.
Published: October 2005

Fourteen young guinea pigs were individually exposed to 500 rounds of paper “caps” tired in a toy gun at a distance of 30 cm. The gun was fired at intervals of 1 5 sec. After seven weeks survival, the cochleas were removed and each complete organ of Corti examined, using Engström's surface-preparation technique. Cochleograms (tabular forms showing position and condition of each cell) were prepared for each row of hair cells. Curves were plotted showing number of damaged cells as a function of distance from the base. In approximately 80% of the cases, total destruction of hair cells occurred in a narrow band midway along the organ of Corti. The severity and distribution of damage for the group are compared with similar data for another group, which was exposed to high-intensity pure tones.
Signal Duration and Signal Frequency in Relation to Auditory Sensitivity
Authors: Watson Charles S. , Gengel Roy W.
Published: October 2005

Levels of monaural signals at behavioral threshold were determined by a psychophysical method of adjustment for seven highly trained listeners. Thresholds were studied as a function of signal frequency (octave steps, from 0.125 to 8 kHz) and of signal duration (logarithmic steps, from 16 to 1024 msec). Measurements were made in the presence of a contralateral broad-band masking noise with a spectrum level of 30 dB SPL. The time constant, τ estimated from at least 12 replications of each measurement, was found to range systematically from values considered normal (125–175 msec) by some earlier investigators, at low frequencies, to much lower values (30–70 msec) at high frequencies. Comparison between the performance of listeners with normal audiograms and those with high-frequency hearing loss shows this interaction between frequency and the time constant to be similar for both samples. The data are also compared to the results of a second experiment that employed a two-alternative forced-choice psychophysical method.
Influence of Pulsed Masking on the Threshold for Spondees
Authors: Wilson Richard H. , Carhart Raymond
Published: October 2005

The changes in masking for spondee words that result from varying both the level and the interruption rate of a white-noise masker were studied with 14 normal hearing subjects and 14 subjects with sensorineural hearing loss diagnosed as resulting from cochlear otosclerosis. The masker was a white noise and was presented monaurally at either 90 dB sound-pressure level (SPL) or 30 dB sensation level (SL). It was either continuous or was pulsed at rates of 1, 10, or 100/sec with 50% duty cycle. During the burst-off half of each cycle, the noise was either dropped 14 dB in level or was fully interrupted. The masked speech reception threshold (SRT) was not improved re the masked SRT in continuous noise when the 30 dB SL masker was pulsed 100 times/sec. Reduction in masking was observed under all other circumstances of cycling the noise. This reduction was more pronounced when the noise was completely interrupted rather than only modulated by 14 dB, when the masker was at its higher level (90 dB SPL as opposed to 30 dB SL), and when the masker was interrupted at the slowest rate [1 interruption per second (ips)]. During equivalent conditions, the reduction in masking was greater for normal-hearing subjects than for those with cochlear otosclerosis. Appreciable residual masking (re SRT in quiet) persisted across the range of all parameters of noise level, modulation depth, cycling rate, and type of subject encompassed during the present study. This last finding appears to be contradictory to some of the results from earlier studies but not to others. This discrepancy, along with other aspects of the present findings, are discussed.
Acoustic-Radiation Force on a Solid Elastic Sphere
Authors: Hasegawa Takahi , Yosioka Katuya
Published: October 2005

The acoustic radiation force on a solid sphere suspended freely in a plane progressive sound field is calculated taking into account the elasticity of the sphere. The radiation force versus ka curve, ka being the radius times the wavenumber in the surrounding medium, shows sharp maximums or minimums corresponding to resonance in every normal mode of free vibration of the sphere. The measurements made in our laboratory are in good agreement with the theory. The accuracy of absolute acoustic-intensity determination by the radiation-force method will be improved by the use of the present theory instead of King's.
Average Power and Power Exchange in Oscillators
Authors: Gersch Will
Published: October 2005

Integral and algebraic equations for the computation of average kinetic, potential, and dissipative energies in systems of randomly excited coupled oscillators are developed. The latter equations are equivalent to those that appear in the study of the Lyapounov stability of linear dynamical systems. A numerical procedure comparable to the known engineering-literature computations of Lyapounov stability is developed and illustrated here. It is also compared with the solution of the stochastic dual of the Lyapounov-stability problem, the computation of “mean-square-response” matrices (Gersch). The known Lyapounov-stability solutions require inversion of a matrix whose order increases as the square of the number of degrees of freedom; the latter require the inversion of a matrix whose order increases linearly with the number of degrees of freedom. Exact results for average power exchange between two arbitrary oscillators and average power coupled into an arbitrary oscillator (in an n oscillator system) are obtained in terms of second moment (mean-square response) computations. In an illustrative example of a 3-degrees-of-freedom system, the exact expression for average power transfer is evaluated to permit an interpretation of earlier approximate analysis by Lyon and Newland on average energy transfer in complex structures.
Rayleigh and Lamb Waves on Cylinders
Authors: Bunney R. E. , Goodman R. R. , Marshall S. W.
Published: October 2005

Acoustic waves propagating on the surface of solid and hollow elastic cylinders immersed in water were observed and their characteristics shown to be consistent with theory. These waves were excited by an 11-μsec pulse, projected onto the cylindrical surface at an excitation angle given by sin 1(co/cs), where co is the velocity of sound in water and cs is the velocity of the surface wave. The waves may be observed, since they continually radiate energy back into the water at the excitation angle. Surface waves were observed to exist on pure (98%) aluminum, 304 stainless steel, and various aluminum-alloy cylinders. Circumference-to-wavelength ratios were varied from 10 to 400 to discern the dispersive effects owing to the curvature of the target. It was also found that inhomogeneities correlate with pure propagation characteristics in some of the targets. The waves observed on air- and water-filled cylinders immersed in water are shown to correspond to the symmetric and antisymmetric vibrations in the shell.
Reply to “Comments on ‘Natural Frequencies and Modes of Skew Membranes’” [P. A. Laura, J. Acoust. Soc. Amer. 45, 1281(L) (1969)]
Authors: Durvasula Somayajule
Published: October 2005

Additional references to the vibration problem of clamped skew plates, including theoretical and experimental investigations by the writer, are pointed out in this letter.
Interaural Time and Amplitude jnds for a 500-Hz Tone
Authors: Hershkowitz R. M. , Durlach N. I.
Published: October 2005

Preliminary experiments were performed on the discrimination of interaural time and the discrimination of interaural amplitude for lateralization images both on and off the midline, using a common set of subjects and a common experimental configuration. The results are compared with some previous work on interaural discrimination and time-intensity trading and with the prediction of the EC model relating interaural time discrimination to interaural amplitude discrimination.
Modulated Frequency Discrimination in Relationship to Age and Musical Training
Authors: Madsen Clifford K. , Edmonson Frank A. , Madsen Charles H.
Published: October 2005

The purpose of the study was to test auditory discrimination of a modulated frequency. Two hundred subjects participated in the study representing second graders, fifth graders, eighth graders, eleventh graders, college non-music majors (juniors), junior music majors, graduate music students, and School of Music faculty, respectively. The stimulus frequency was F♯ (369.99 Hz), which was presented to subjects individually in 15 randomized 30-sec trials in three catagories: (1) without frequency alteration; (2) ascendingly; and (3) descendingly. Modulation for the ascending and descending tones was 2 cents/sec during the last 25 sec of the stimulus tone. Results of the study indicate that: (1) Auditory discrimination is partially a function of age as well as of music training; (2) comparatively, younger subjects respond to tonal stimuli “incorrectly and sharp” while older subjects evidence “better discrimination while demonstrating a proclivity toward flatness”; (3) perception of the modulated frequency is best during the first 5 sec (10 cents) of frequency change; and (4) auditory tests that attempt to assess discrimination should control for guessing as well as for directional, i.e., up-down, propensities.
The FROC Curve: A Representation of the Observer's Performance for the Method of Free Response
Authors: Miller Harold
Published: October 2005

In a YES-NO signal detection task, the observer's performance can be represented by an ROC curve. In a free-response task, an ROC curve cannot be plotted because the observation interval is not defined. However, if the responses can be partitioned into hits and false alarms, then the observer's performance can be represented by an FROC curve, which possesses many of the properties of an ROC curve. FROC curves are obtained from a single observer in a vigilance task to demonstrate its use.
Limits for the Detection of Binaural Beats
Authors: Perrott David R. , Nelson Michael A.
Published: October 2005

This study investigates the probability of detecting binaural beats as a function of the frequency of the standard signal used (f1) and of the dichotic frequency difference (|f1−f2|). The present findings indicate that the upper frequency limit for the perception of binaural beats depends upon the dichotic frequency differences employed, the psychophysical procedure used, and the criteria for a beat threshold. The probability of beat detections was maximal at 500 Hz, and decreased as frequency increased up to 1500 Hz. No reliable pattern of beat detections was observed above 1500 Hz. Binaural beats were obtained with both “fused” and “nonfused” dichotically presented signals. Implications for a general model were discussed.
Vocal-Tract Characteristics of the Stop Cognates
Authors: Kent R. D. , Moll K. L.
Published: October 2005

Cinefluorographic films and throat microphone recordings were obtained from three male speakers for 18 pairs of utterances in which one member of a pair differed from the other only in a stop cognate, i.e., /p, t, k/:/b, d, g/. The data reveal that, although stop cognates are similar in the characteristics of the constrictory articulation, the voiced stop is produced with a larger supraglottal volume than its voiceless cognate. The volume differences are caused by a lengthening and expansion of the oropharynx during voiced stops. These processes, which probably satisfy the aerodynamic requirements of voicing, are interpreted to be the results of muscular action rather than passive responses of the vocal tract. Further observations concern the articulatory dynamics of consonant production and may be relevant to the description of neuromotor commands in speech production.
Proposed Explanation of Synchrony of Auditory-Nerve Impulses to Combination Tones
Authors: de Boer E. , Kuyper P. , Smoorenburg G.
Published: October 2005

When the acoustic stimulus consists of two sinusoidal components (frequencies f1 and f2), the impulses of a single auditory-nerve fiber can show partial synchrony with either of these components (provided the frequencies stay below approx 5 kHz). Often a synchrony with an externally generated combination tone of frequency 2f1−f2 can be detected as well. It is shown in this letter than such a behavior is a logical consequence of the assumption that nerve impulses are elicited at the peaks of the stimulus waveform. In addition, it is demonstrated that only special combination tones will show this phenomenon. Many of the experimental results on this type of synchrony can be explained in this way. It is thus not necessary to assume that a special physiological mechanism is responsible for the observed synchrony per se. But deviations from the basic properties derived here should be observed closely, because these do give useful indications about cochlear physiology.
Auditory Sensitization
Authors: Melnick William
Published: October 2005

Temporary threshold shift (TTS) was measured for 15 males with normal hearing under four conditions: immediate versus delayed test onset, and 3 min of 1000 Hz at 40 dB sensation level versus 3 min of quiet during the exposure period. Time of test onset showed no effect. Negative TTS was observed for both exposure conditions with significantly more being produced by the quiet condition.
Waveform Preservation in the Cochlea
Authors: Nordmark Jan O. , Glattke Theodore J. , Schubert Earl D.
Published: October 2005

Past measurements and observations appear to give equivocal evidence on whether waves of different frequency travel down the cochlea at the same rate. If different frequencies travel at different rates, then steady-state waveforms will show changes in addition to those attributable to relative amplitude change of the components. Sinusoids of simple (octave) ratio were fed into guinea-pig cochleas, and the waveforms were observed with paired electrodes at two well-separated points. Comparative phase shifts for the two components indicate that, on the stapes side of a given observation point along the membrane, all frequencies lower than the frequency of maximum amplitude for that point travel at the same rate.
An EMG Electrode for the Diaphragm
Authors: Hixon Thomas J. , Siebens Arthur A. , Minifie Fred D.
Published: October 2005

A new electrode for sensing the electrical activity of the human diaphragm is described. The electrode is a bipolar surface unit employed in an esophageal approach to the fibers of the diaphragm comprising the esophageal hiatus. Procedures for its use in human subject are discussed.
Mechanism of Production of Cochlear Microphonics
Authors: Honrubia Vicente , Ward Paul H.
Published: October 2005

An analog equivalent electrical circuit of the cochlea that follows the principles of the electromechanical hypothesis for the function of the organ of Corti has been studied. The steady-state parameters of this heuristic electrical model were calculated from data about the impedance and potentials' differences that exist across the walls of the cochlear partition. The behavior of the model is such that it replicates many observations obtained during experiments on the cochleas of guinea pigs. The model also affords a qualitative as well as quantitative approach to the study of the directions, magnitude, and source of electric currents flowing through the inner ear during acoustic stimulation. It also offers a deeper insight into the role played by the main functional elements of the organ of Corti.
Frequency Discrimination in the Adapted Ear
Authors: Nielsen Donald W. , Fraser Winifred D. , Elliott Donald N.
Published: October 2005

The quality of the auditory experience produced by sinusoidal stimulation changes with increased duration. These changes in quality of the experience produced by an adapting stimulus suggested the possibility of a change in the frequency-discrimination limen (DLf) and a shift in pitch. The effects of adaptation on monotic and dichotic DLf and on pitch shift have therefore been determined. Data were obtained under normal and adapted conditions at two frequencies (250 and 1000 Hz), two intensities (40 dB SL and 60 dB SL), and with two modes of presentation (monotic and dichotic). DLf and constant-error (CE) measures were calculated. The DLf analysis showed significant results for the main effects of frequency, adaptation, and mode of presentation. Results of the CE analysis showed no statistical significance.
Effects of High Frequencies and Intersubject Variability on the Auditory-Evoked Cortical Response
Authors: Rothman Howard H.
Published: October 2005

Tone bursts of 2, 4, 6, and 8 kHz, with rise-fall times of 20 msec and durations of 200 msec, were presented to human subjects, through earphones, at sensation levels (SLs) of 10, 30, 50, or 70 dB. The tones were delivered once per second, in blocks of 60, at a specific frequency and SL. Sixteen combinations of frequency and SL were employed, and were presented in a counterbalanced order, with four replications per combination for each subject. Simultaneously with each burst, the slow, evoked response (V potential) was recorded between vertex and mastoid. Evoked response amplitudes (N1 − P2) were found to decrease with increasing frequency, particularly at higher sensation levels. The slopes of the input-output functions also decreased with frequency, though differences between subjects influenced slope even more than frequency. The input-output data, when fitted by straight regression lines, generally showed the same goodness of fit, whether plotted on logarithmic or linear ordinates, versus SL.
System for Automatic Formant Analysis of Voiced Speech
Authors: Schafer Ronald W. , Rabiner Lawrence R.
Published: October 2005

A system for automatically estimating the lowest three formants and the pitch period of voiced speech is presented. The system is based on a digital computation of the cepstrum (defined as the inverse transform of the log magnitude of the z-transform). The pitch period estimate and smoothed log magnitude are obtained from the cepstrum. Formants are estimated from the smoothed spectral envelope using constraints on formant frequency ranges and relative levels of spectral peaks at the formant frequencies. These constraints allow the detection of cases where two formants are too close together in frequency to be resolved in the initial spectral envelope. In these cases, a new spectral analysis algorithm (the chirp z-transform algorithm) allows the efficient computation of a narrow-band spectrum in which the formant resolution is enhanced. Formant and pitch period data obtained by the analysis system are used to control a digital formant synthesizer. Results, in the form of spectrograms, are presented to illustrate the performance of the system.
Auditory Thresholds during Visual Stimulation as a Function of Signal Bandwidth
Authors: Moore Ernest J. , Karlovich Raymond S.
Published: October 2005

A Béḱsy-type tracking procedure was employed with eight male subjects to obtain auditory thresholds for pulsing wide-band. low-band, mid-band, and high-band noise during nonvisual and visual stimulation periods. Thresholds and attenuator pen-excursion sizes obtained for each bandwidth auditory stimulus were not significantly different between nonvisual and visual condition. The data indicated that psychophysical sensory interaction between the auditory and visual systems did not occur for the stimulus used, that is, auditory thresholds were neither facilitated nor inhibited during presentation of a time-locked stroboscopic visual stimulus.
A Further Note on “Limits for the Detection of Binaural Beats” [D. R. Perrott and M. A. Nelson, J. Acoust. Soc. Amer. 46, 1477–1481 (1969)]
Authors: Perrott David R.
Published: October 2005

A comparison is made between the limits for the detection of binaural beats and the limits for the detection of binaural “fusion.” The functions obtained for these two phenomena appear to be independent.
Influence of Diffusivity on the Transmission Loss of a Single-Leaf Wall
Authors: de Bruijn A.
Published: October 2005

Cremer's theory of sound transmission for a single-leaf wall is transformed into a more general formulation in which the exciting pressure is expressed in terms of the spatial cross-correlation. The correlation coefficient was measured in a reverberation room just in front of the wall under test. The sound-transmission loss of a single gypsum-board wall was calculated employing these diffusivity measurements and compared with experimental data. Agreement between theory and experiment is good, especially in the frequency range below the coincidence frequency. Finally, a few fictitious quasidiffuse sound fields are investigated further study of the influence of the degree of diffusivity upon transmission loss.
The Directivity of Sonar Receiving Arrays
Authors: Queen William C.
Published: October 2005

General expressions are developed for determining the beam patterns and directivity index of arbitrary configurations of hydrophones and results given in the special case of a cylindrical shell array. The limiting case of a continuous distribution of hydrophones is considered and integral relationships are derived for volume and shell distributed array. Closed-form solutions are obtained in the case of a sphere and cylinder, and results show the response of the volume array to be superior to that of a corresponding shell array. Comparisons also show the directional characteristics of a cylindrical shell array to agree quite well with those of a corresponding discrete array whose phone spacing is less than one-half wavelength.
Free-Field Technique for Measuring Ultrasonic Dispersion and Absorption in Gases
Authors: Blend Harvey
Published: October 2005

This is a method for determining the phase velocity and attenuation of a progressive sonic wave by means of electronic interferometry. The wavelength λ and the frequency f are very accurately measured and then combined in the well-known relationship, V = λf, to give the velocity V. To eliminate the effects of echoes, sine bursts are produced by gating an amplifier driven by a CW reference oscillator. Utilizing a calibrated attenuator, the received burst is added to the CW reference to show a null each time the sound receiver is moved through a wavelength. This addition and null are displayed on a cathode-ray oscilloscope. Wide-band solid dielectric transducers are employed to give a frequency span of 1 kHz to 1 MHz. The precision and reproducibility of the velocity measurements are within 0.01%. Sound transmission can be measured over a range of 110 dB to within 0.1 dB. Temperature is controlled from −20° to +60°C to within 0.1°C.
Hypersonic Velocity and Absorption in Aqueous Electrolytic Solutions
Authors: Montrose C. J. , Fritsch K.
Published: October 2005

Hypersonic velocity and absorption measurements were made in a number of aqueous solutions, using the technique of Brillouin scattering. These light-scattering experiments represent the first direct measurement of the solvent absorption in the presence of salt ions. The results indicate that in dilute solutions this is about equal to the absorption in pure water, Al2(SO4)3 being the principal exception. Concentrated (4M) NaCl and NaBr solutions also showed an absorption value different from that of water. The differing absorption values were accompanied by substantially larger values of the speed of hypersound.
Energy Conservation for Rough-Surface Scattering
Authors: Lynch P. J. , Wagner R. J.
Published: October 2005

The neglect of multiple-scatter and shadowing effects in the theory of high-frequency scatter from random rough surfaces is manifested as a nonphysical energy loss or gain. This is demonstrated most clearly when the scattered intensity is cast in the form of the probability density of specular slopes. Shadowing is accounted for by introduction of the probability of illumination, conditional on the slope. Energy is then conserved for near-grazing incidence.
Empirical Determination of Air-Water Impedance Differences in Small Tanks
Authors: Weiss Burton A.
Published: October 2005

Airborne sonic pressures in an open or sealed housing enclosing an aquarium were measured in the air and in the water under near- and farfield conditions. Effective impedance differences were 9.1 dB with the housing open and 4.5 dB with the housing sealed in the nearfield, and 6.5 dB in the open condition and 7.1 dB in the closed condition in the farfield. Both conditions indicated an effective impedance difference considerably less than the 35.5 dB impedance difference between air and the open ocean. Prevalent use of sonic fields in small aquariums thus requires detailed calibration of sonic fields in tanks where the air-water interface is traversed. Because of the 30 dB loss from disruption of the ossicular chain, the ear, in spite of anatomical likeness, is not similar to a closed speaker (eardrum) system over a water-filled tank (cochlea).
Near-Front Stress Singularity for Impact on an Elastic Quarter-Space
Authors: Freund L. B. , Phillips J. W.
Published: October 2005

An asymptotic analysis of the grazing-incidence problem is made for the point where the traction-free boundary of an elastic solid intersects the front of the plane pulse propagating parallel to it.
Thermal Analogy for the Dynamics of Piezoelectric Shells
Authors: Wilkinson J. P. D.
Published: October 2005

An analogy is noted between the behavior of a transversely isotropic circumferentially polarized piezoelectric shell of revolution and the behavior of an elastic orthotropic shell of revolution under a given temperature distribution.
Acoustics of Northrop Memorial Auditorium
Authors: Ramakrishna B. S. , Smits T. I.
Published: October 2005

The Northrop Memorial Auditorium is a multipurpose hall with a seating capacity of 4800 in the auditorium and a hundred or more on the stage. It is unique among halls of its size in having, perhaps, the smallest volume per seat (∼210 ft3/seat) and the lowest reverberation time (0.94±0.1 sec). The paper presents the results of measurements on (1) reverberation times, (2) noise levels, (3) sound-pressure-level distribution, and (4) intelligibility of speech. By comparison with previous measurements, the acoustical results of some changes made in the auditorium have been assessed. It is hoped that, in turn, these measurements will furnish a reference point in evaluating the outcome of a major remodeling the hall is about to undergo. An attempt is made to relate the physical measurements to the psychoacoustical responses experienced in the hall. The role of sound reinforcement systems in determining the subjective response and hence in choosing a suitable reverberation time for multipurposes halls is discussed briefly.
Adaptation: Central or Peripheral?
Authors: Fraser Winifred D. , Petty Joseph W. , Elliott Donald N.
Published: October 2005

Adaptation was measured using successive and simultaneous presentation of heterophonic stimuli in order to determine if adaptation is more a central than a peripheral phenomena. The first of the two studies reported compared the method of delayed balance, method of simultaneous dichotic balances (SDB) involving tracking for 15-sec periods, and a modification of the SDB utilizing 1-sec tones. Only the homophonic SDB involving tracking produced noticeable adaptation. In the second experiment several procedural variations of the heterophonic tracking SDB method were studied. None of the variations produced the intensity decrement customarily associated with adaptation. It was concluded that, when binaural interactions (loudness and/or lateralization) are reduced or eliminated by test procedures, the adapted ear shows little if any shift. Thus, the decrements observed with the typical SDB procedure probably reflect slowly developing changes in binaural interactions—and, consequently, are central rather than peripheral changes. Judgments obtained with simultaneous stimulation, therefore, are not procedures that should be utilized for the study of peripheral adaptation effects.
Introductory Experiments in Auditory Time Sharing: Detection of Intensity and Frequency Increments
Authors: Moray Neville
Published: October 2005

Two preliminary experiments in a program to investigate the psychophysics of auditory attention are reported. Listeners were required to detect changes in intensity and frequency in pure-tone bursts of 100-msec duration under four conditions of attention, including undivided and divided attention. In the divided attention conditions, there was a lowering of the proportion of targets detected, and this was particularly true when targets occurred simultaneously on two channels with both requiring a response.
Monaural Detection of a Phase Difference between Clicks
Authors: Ronken Don A.
Published: October 2005

Pairs of very brief pulses can be arranged to produce transient signals having spectra that differ only in power, only in phase, or in both power and phase. Conventional intensity discrimination for such click pairs is obtained by using the signals that differ only in their power spectra. Some of the corresponding signals that differ only in their phase spectra are also readily discriminable. An attempt is made to assess the relative saliency of the power and phase variables by adding the phase cue as a distracting feature to the power-discrimination task. The presence of such an uncorrelated phase cue can lower the detectability of power differences.
Effects of Intense Noise during Fetal Life upon Postnatal Adaptability (Statistical Study of the Reactions of Babies to Aircraft Noise)
Authors: Ando Y. , Hattori H.
Published: October 2005

The manner in which infants react to aircraft noise was investigated at Itami City, located at the Osaka International Airport. The subjects were 188 babies whose mothers had moved to Itami City from quiet places, who were classified into the following four groups. Groups I and II were composed of 77 and 45 infants whose mothers came to Itami City before pregnancy or during the first five months of pregnancy, respectively. Groups III and IV were composed of 22 and 44 infants whose mothers came to this City during the latter five months of pregnancy or after childbirth, respectively. In Groups I and II, over 48% of the babies slept soundly and less than 13% awakened and cried on exposure to aircraft noise. On the other hand, in Groups III and IV, less than 15% slept and 50% awakened at the noise. The differences in reactions between Groups I and II and Groups III and IV were obvious and, on the basis of these differences in reactions, it is hypothesized that during the first five months of pregnancy, acoustic information is conveyed from the mother to the embryo that enables the infant adapt to the noise.
Auditory Function, Communication, and the Brain-Evoked Response in Anuran Amphibians
Authors: Loftus-Hills Jasper J. , Johnstone Brian M.
Published: October 2005

The role of tuned auditory receptors in the acoustical communication system of frogs was investigated by studying the hearing characteristics of nine anuran species. A signal-averaging computer was used to record the brain-evoked response to acoustic stimuli, and the general characteristics of this response in relation to stimulus frequency, intensity, duration, and repetition rate were examined. The response was used to obtain audiograms for the nine species. These hearing curves had two regions of maximal frequency sensitivity, probably derived from separate auditory receptors, the amphibian and basilar papillae. The frequency of one of these sensitivity peaks was different for each species. Six of the species utilize common breeding sites and, at least potentially, interact acoustically. For five of these, the spectral composition of the mating call (a species specific acoustic signal) matched the respective upper-frequency sensitivity peak. This pattern of tuned hearing is presumably related to problems of communication in mixed species choruses. The absolute sensitivity of these peaks varied in each species, markedly decreasing at higher frequencies. It is suggested that at higher frequencies, a limitation of the transmission characteristics of the middle ear has confined the acoustical communication system of anurans mainly to sounds below 5 KHz. The importance of frequency in mating-call discrimination is discussed.
Representation and Analysis of Time-Limited Signals Using a Complex Exponential Algorithm
Authors: Spitznogle Frank R. , Quazi Azizul H.
Published: October 2005

A complex exponential algorithm developed for the representation and analysis of time-limited signals is defined, and its evaluation with respect to conventional discrete Fourier techniques is discussed. It is shown that for a given length of a signal containing discrete frequency information, sampled at least to the Nyquist criterion, the complex exponential algorithm can often provide increased frequency resolution over standard Fourier techniques. It is also shown that the complex exponential algorithm provides an improved mechanism over Fourier techniques for interpolation between points in a sampled signal containing discrete frequency components in the presence of broad-band noise. The effects of noise in the complex exponential technique and the computational difficulties associated with the present complex exponential algorithm are also discussed.
Transient Effects in the Propagation of a Sound Pulse in a Viscous Liquid
Authors: Moffett Mark B. , Beyer Robert T.
Published: October 2005

The propagation of an ultrasonic pulse (f≈10 mHz) in a viscous liquid, CCl4, has been experimentally investigated. As the path length increased, the pulse developed a precursor. Furthermore, the first peaks of the pulse were attenuated nonexponentially, persisting over much larger distances than later peaks in the pulse. These effects were noticeable for propagation distances x ≳ 1/α, where α is the amplitude-absorption coefficient. Theoretical results of Blackstock [J. Acoust. Soc. Amer. 41, 1312–1319 (1967)] for a step-modulated sinusoidal pulse were modified to take into account the actual shape of the experimental pulse at x = 0. Comparison of the expected and measured pulse shapes gave good agreement for the peak positions, but only qualitative agreement for the peak heights. This discrepancy is probably due to the finite thickness of a bonding layer in the acoustic receiver.
Structural-Relaxation Dynamics in Liquids
Authors: Montrose C. J. , Litovitz T. A.
Published: October 2005

Structural-relaxation data in liquids indicate the presence of a distributed relaxation-time spectrum. A physical model for this distribution is proposed. The model is used to calculate the dynamical behavior of fluctuations in an order parameter describing the local liquid structure. This is used to predict both compressional and shear relaxation dynamics. The equation of motion for the ordering parameter includes explicitly both the effects of an elementary rate process and simple diffusion. The calculated distribution of relaxation times for compressional strain is similar to a Cole-Davidson distribution function with a width parameter near 0.5. The predictions for the frequency dependence of the compressibility and shear rigidity agree reasonably well with experimental data in a number of liquids.
Movie Films of Cavitation in Superfluid Helium
Authors: Mossé A. , Chu M. L. , Finch R. D.
Published: October 2005

Movie films of cavitation in helium II have been taken which show that bubbles occur in the form of streamers which can persist for hundreds of sound cycles. The streamers are frequently paired, apparently having a common point of origin. The threshold for visible events shows hysteresis, in that different values are obtained for incipient and desinent cavitation. The significance of the observations is discussed.
On Obtaining Transition Rates from Sound Absorption and Dispersion Curves
Authors: Shields F. Douglas
Published: October 2005

The problem of obtaining transition rates from acoustic measurements of vibrational-relaxation times is discussed. The error involved in using the Schäfer equation, τ1 = τ1C1/ΣiCi, to obtain the relaxation times for a single mode from the measured relaxation time is evaluated by calculating the sound absorption and dispersion from the reaction equations, using the method of Tanczos. The analysis shows that the absorption and dispersion curves closely approximate the single-relaxation-time curves in a series relaxation process, as long as the vibration-vibration (v-v) transfer is at least as fast as the vibration-translation (v-t) transfer. The calculations rule out a v-v process for the CO2/H2O interaction.
Coherent Detection Technique for Variable-Path-Length Measurements of Ultrasonic Pulses
Authors: Williamson R. C. , Eden D.
Published: October 2005

A technique for the accurate measurement of ultrasonic velocity and attenuation in fluids is presented. The additional delay and decrease in amplitude of an ultrasonic pulse, resulting from an increase in the length of the transmission path, are precisely measured by phase comparison of the received ultrasonic signal with a continuous coherent reference signal at the carrier frequency. Phase-sensitive detection in a balanced mixer provides a phase-detector output, which is linear, sensitive to small delay changes, and has a high signal-to-noise ratio. The technique is well suited for measurements in highly attenuating fluids. Ultrasonic propagation near the critical point of xenon was studied using this technique. Attenuations in excess of 400 dB/cm were measured at 1 MHz.
Acoustic Radiation from Partially Coherent Line Sources
Authors: Butler John L. , Sherman Charles H.
Published: October 2005

A simple mathematical model is discussed for the partially coherent sound field produced by distributions of arbitrarily correlated point radiators. The model is then applied to line sources in order to illustrate various features of the cross power spectral density in partially coherent sound fields.
On the Use of Slowness Diagrams to Represent Wave Reflections
Authors: Crandall Stephen H.
Published: October 2005

Slowness diagrams facilitate the determination of plane-wave reflection patterns. A small addition to the conventional diagram makes it possible to represent the decay rates of plane waves with complex slowness. A complete survey is made of all causal reflection patterns for an isotropic elastic half-space with a stress-free boundary.
Dynamic Shell Theory for Ferroelectric Ceramics
Authors: Drumheller Douglas S. , Kalnins Arturs
Published: October 2005

A coupled theory for the vibration analysis of piezoelectric shells of revolution is presented, which satisfies all electrostatic and elasticity equations within the limits of a shell theory. As an illustrative example, the free vibration characteristics of a hollow cylinder made of ferroelectric ceramic PZT-4 are calculated in detail. Resonant frequencies are given as a function of the length of the cylinder. The relations of the electrical admittance and the electromechnical coupling with the frequency are shown. The comparison of these results to those of uncoupled theories, given previously, is discussed.
Moving and Simultaneously Fluctuating Loads on an Elastic Half-Plane
Authors: Keer Leon M.
Published: October 2005

By using the techniques of Fourier transforms, certain problems dealing with moving and simultaneously fluctuating load distributions on an elastic half-plane are formulated and solved. It is found that a symmetrical load distribution will result in a displacement response beneath the load that is asymmetric.
Wave Propagation in an Infinite Elastic Plate in Contact with an Inviscid Liquid Layer
Authors: Walter W. W. , Anderson G. L.
Published: October 2005

The dispersion relation for straight-crested waves in an isotropic plate in a state of plane strain that is covered by a layer of an incompressible liquid is derived and investigated in the limits of very long wavelengths (thickness-stretch vibrations of the plate-liquid system) and of very short wavelengths (surface waves at the solid-liquid interface). In the case of surface waves, there are two dispersive modes, one predominantly elastic (analogous to Rayleigh waves) and the other essentially fluid, and in the thickness-stretch case there are an infinite number of essentially elastic modes and one fluid mode. An approximate version of the dispersion relation valid for arbitrary wavelengths is obtained by using two nonclassical plate theories to account for the extensional and flexural deformations of the plate. This relation gives rise to five modes on the real branch, which are identified as being thickness-stretch, thickness shear, flexural, extensional, and fluid in character, and three modes on the imaginary branch, namely, flexure, thickness-shear, and thickness-stretch. Two of the five cutoff frequencies are modified by the presence of the liquid layer. A variety of numerical results is presented in graphical form.
Wave Attenuation in Saturated Sediments
Authors: Stoll Robert D. , Bryan George M.
Published: October 2005

This paper considers a mathematical model to describe the propagation of low-amplitude waves in saturated sediments. Losses due to inelasticity of the skeletal frame and to motion of the pore fluid relative to the frame are both accounted for, and each is found to be significant in a different frequency range. The theory shows favorable agreement with experimental results where available for both sands and finer-grained sediments over a wide range of frequencies.
Damping Constants of Pulsating Bubbles
Authors: Eller Anthony I.
Published: October 2005

Results obtained by Devin [J. Acoust. Soc. Amer. 31, 1654–1667 (1959)] for the damping constants of resonant bubbles are extended to the off-resonance case. Calculated results show for the range of conditions considered that thermal damping is important for bubbles driven below resonance, and radiation damping is important for those above resonance.
Comments on “Analysis of an Integral Equation Arising from the Investigation of Vertical Directivity of Sea Noise” [M. W. Anderson and R. L. Tittle, J. Acoust. Soc. Amer. 45, 1129–1133 (1969)]
Authors: Stickler D. C. , Fox G. R.
Published: October 2005

The mathematical argument presented in the subject paper is discussed, emphasizing the essential difference between the cases of electrical and mechanical steering of a linear receiving array.
Observations of Oscillatory Radial Flow between a Fixed Disk and a Free Disk
Authors: Chanaud Robert C. , Bobeczko Michael S.
Published: October 2005

When air flows radially between two parallel disks, one fixed and the other free, self-excited oscillations occur, generating a loud tone. The fundamental frequency of these oscillations increases with increasing flow, and this frequency is closely related to the axisymmetric flexural modes of the free disk. A possible mechanism for maintaining the oscillations is given.