bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of Aural Harmonics along the Basilar Membrane of Guinea Pigs
Authors: Tonndorf Juergen
Published: September 2005

Harmonic distortion has been shown to originate hydrodynamically in cochlear models; its essential manifestation being Békésy's “eddies” and their sequelae. One of the major postulates derived from this study was that the distortion be resolved along the cochlear partition in accordance with the place principle of frequency localization.

Experiments on guinea pigs were conducted in an effort to support this latter postulate. A method of recording cochlear microphonics by means of differential electrodes was chosen. This method had been previously used by Tasaki, Davis, and Legouix for mapping amplitude and phase alteration along the basilar membrane.

The results of the present study indicate (1) that distortion within the cochlea occurs at a lower intensity level than it does in the middle ear (confirming results of earlier investigators), and (2) that each newly created harmonic forms a traveling-wave pattern of its own along the basilar membrane in accordance with the place principle. These results support the hydrodynamic hypothesis of the origin of intracochlear distortion.
Construction of Calculable High Acoustic Resistances
Authors: Bogner R. E.
Published: September 2005

This Letter describes a convenient technique that was used to make acoustic resistances of the order of 108 Ω (mks acoustic). Each resistance was formed by compressing a short piece of copper tube onto a steel shim of known dimensions.
Reflectoscope Angle Probe with an Indicator of the Degree of Coupling to the Test Object
Authors: Lutsch A.
Published: September 2005

A plastic wedge angle probe for a reflectoscope for nondestructive testing purposes is described, in which the amount of energy transferred to the object under test is measured, in order to be sure that enough energy is available for testing welds, machine parts, etc. The amplitude of the compressional wave reflected into the plastic wedge is measured by means of a second crystal. The pulse amplitude acoustically compensates for one extreme coupling case. The measurements were done at 2.5 Mc/sec.
Tracking Oscillator-Analyzer Scheme
Authors: Bogner R. E.
Published: September 2005

The system described is in effect a heterodyne wave analyzer that tracks the output of a beat-frequency oscillator (BFO). The “local oscillator” of the wave analyzer is provided by taking output from the variable oscillator of the BFO. The system may be assembled readily front normal laboratory instruments and has been very useful in precision calibration of microphones.
Reflection from a Fluid of Higher Sound Velocity
Authors: Savage James C.
Published: September 2005

The method of Cagniard is employed to obtain an exact solution for the pressure response to a spherically symmetric acoustic pulse originating at a source within a semi-infinite fluid bounded below by a fluid of higher sound velocity. The solution is expressed in terms of elliptic integrals. The shape of that portion of the response known as the refracted arrival is shown to depend principally upon the density contrast. The response is plotted as a function of time for parameters which represent the reflection process from the ocean bottom. If the pulse from the source has a steep initial rise time, then reflection at angles greater than the critical angle may lead to unexpectedly large amplitudes for a brief time interval. It is suggested that this phenomenon may introduce nonlinear effects into the reflection process.
Stimulus Correlates of Wave Activity in the Superior-Olivary Complex of the Cat
Authors: Boudreau James C.
Published: September 2005

Wave activity in response to tonal stimuli was recorded in the superior-olivary complex of anesthetized cats. A rapid and a slow phase of adaptation were observed. The intensity-amplitude curves were found to approximate power functions, with an average exponent of 0.34 for an 800-cps stimulus. The intensity-amplitude functions for stimuli between 200 and 2400 cps tended to form families of curves with maximum amplitudes between 500 and 1000 cps. Some factors inducing variability were discussed in detail. Comparison of superior-olive activity with eighth-nerve activity as described in published reports suggested that auditory information is transmitted through the cochlear nuclei to accessory nucleus in essentially an unmodified form.
Multiple Cutaneous Stimulation: The Discrimination of Vibratory Patterns
Authors: Geldard Frank A. , Sherrick Carl E.
Published: September 2005

In an effort to supply widespread cutaneous stimulation and thus make possible systematic study of the limits of spatial discrimination through this channel, there has been devised a multiple contactor system permitting application of vibratory signals to 10 bodily loci simultaneously. Patterns comprising from 1 to 9 stimuli were presented in successive pairs, the subject's task being to report whether the patterns were perceived as “same” or “different.” Members of pairs were separated by 500 msec and burst duration was 200 msec. Two synchronized Western Union tape transmitters presented 20 programs of 50 pairs of patterns, 500 “same” and 500 “different” pairs being randomly intermixed in the 1000 presentations. A pilot experiment, in which many types of pattern changes were explored, revealed errors to be associated with (a) relative pattern complexity (large numbers of vibrators) and (b) high degree of communality (many elements in common). A formal experiment, involving a stratified sample with all combinations of numbers of loci and degrees of communality represented equally, verified the preliminary finding, and permitted, in addition, separation of the two factors apparently responsible. The relation between errors and communality, with number of stimulus positions held constant, proves to be an intimate one; confusions between patterns arise when there is relatively large overlap of elements in the patterns to be discriminated. A supplementary analysis, directed at whether particular receptive areas may be especially prone to error, shows no single locus, of the 10 employed, contributing to error production more than would be dictated by chance.
Study of the Intensity Distribution of the Light Diffracted by Ultrasonic Waves
Authors: Miller R. B. , Hiedemann E. A.
Published: September 2005

Detailed measurements of the light intensity of the diffraction orders produced by progressive ultrasonic waves in xylene were made. These were compared to the Raman-Nath theory and to a modification of this theory by Mertens. Although it was found that in some cases Mertens' modifications were significant, there remain deviations between theory and experimental results which suggest that the actual experimental conditions deviate from the usual theoretical assumptions.
Localization Aftereffects with Pulse-Tone and Pulse-Pulse Stimuli
Authors: Thurlow W. R. , Marten Anita E. , Bhatt Bhalchandra J.
Published: September 2005

When a pulse is presented from one position in space near in time to the beginning of a tone burst coming from another position in space, the tone burst may be perceived to be displaced toward the pulse. Measurements of displacement effects are given for various angles of separation of sources and duration of tone. A related type of displacement effect occurs that involves the perceived displacement of one pulse toward another in space when the two pulses are presented with small time separations between them. Another type of effect has been discovered, more closely related to yon Békésy's concept of funneling, in which a pulse appears to be funneled into the spatial location of another that precedes or follows it by a small time interval. A “place” model is presented to help to explain these effects.
New Airborne Sound Transmission Loss Measuring Facility at Riverbank
Authors: Richards R. L.
Published: September 2005

A new sound transmission loss measuring facility has been in use at Riverbank Acoustical Laboratories for more than a year now. This paper describes the two reverberation rooms, installation of the test panel, instrumentation, and measurement technique. The several checks made for measurement accuracy and repeatability are discussed. Test results are given comparing the old method of test with the new, and results are also given for a folding door measured at four testing laboratories in the United States and Canada.
Analysis of Surface-Reflected/Bottom-Reflected Ray Transmissions in Constant-Velocity-Gradient Media
Authors: Jacobson M. J.
Published: September 2005

This paper complements an earlier study of refracted/bottom-reflected rays by the author and considers surface-reflected/bottom-reflected transmissions in a model ocean having a horizontal surface and bottom and sound velocity that decreases linearly with depth. The case of increasing velocity is implicit since transmissions in media with velocity gradients +g and −g are geometrically equivalent. The paper is concerned primarily with an analysis of spreading loss. General expressions are derived for spreading loss, range, and travel time, and the problem of multiple arrivals at a fixed receiving point is examined. The spreading loss along a ray is considered in detail after the ray has experienced many reflections. Detailed results are presented for the case of a bottomed source and receiving point, and these are compared with the corresponding results for refracted/bottom-reflected transmissions.
Propagation at Short Ranges of Elastic Waves from an Impulsive Source in a Shallow Fluid Overlying a Layered Elastic Solid
Authors: Victor A. S. , Spitznogle F. R. , McLeroy E. G.
Published: September 2005

A recent theory for the prediction of the pressure field produced by an impulsive sound source in a fluid overlying an elastic solid layer that rests on a solid half-space is extended to include the effects of an air-fluid boundary above. Experimental-model data are presented to support the theoretical results. It is felt that this extension will aid in the application of the theory to problems of sound propagation in shallow water.
Efficiency of a Linear Array of Point Sources with Periodic Phase Variation
Authors: Embleton T. F. W. , Thiessen G. J.
Published: September 2005

The radiation efficiency of a uniform linear array of point sources with periodic phase variation is evaluated. Two different types of interference are found depending on whether the characteristic length of the phase variation is greater or less than the wavelength of the sound radiated. In its application to suction roll silencing in paper mills it is found to be less effective than a linear continuous phase variation.
Reflection of Gigacycle-per-Second Ultrasonic Waves from an Optical-Contact Bond
Authors: Carr Paul H.
Published: September 2005

The use of optical contact as a low-loss acoustic bond at gigacycle-per-second frequencies has been demonstrated. The reflection of 3- and 9 Gc sec longitudinal waves from an optical contact bond between two X cut quartz rods has been measured to be of the order of 1% of the incident acoustic power at 1.5°K. Thin X-cut quartz disks optically contacted to Z-cut quartz and ruby rods have been used at 1.5°K and found to be about as efficient aa an X-cut rod.
Synchrony of Neural Activity in Electric Responses Evoked by Transient Acoustic Stimuli
Authors: Goldstein Moise H. , Kiang Nelson Y.-S.
Published: September 2005

Electric responses evoked by transient acoustic stimuli were recorded by gross electrodes from the periphery and cortex of the cat. The responses to clicks and to the rapid onset of bursts of noise or tones are characterized by a sharp N1 peak in the peripheral response and by a broader cortical response. When the rise time of the onset of bursts of noise (or tones) is lengthened, or when a burst of sudden onset is presented in a noise background, it is possible to obtain cortical responses under conditions for which the N1 component of the peripheral response is undetectable. These results and associated findings are interpreted by considering the degree of synchronization of the discharge and the wave forms of the activity of units that contribute to responses recorded by gross electrodes. A simple statistical interpretation is presented.
Stereophonic Listening and Speech Intelligibility against Voice Babble
Authors: Pollack Irwin , Pickett J. M.
Published: September 2005

The utilization of a particular form of stereophonic information was studied with respect to the intelligibility of a single speech source heard in the presence of a voice babble of other speakers. The reception of monosyllabic words, presented against a babble of 1, 2, 4, or 7 talkers, was compared under two listening conditions: (1) In the stereophonic listening condition, one set of background talkers was presented to one earphone, another set of background talkers was presented to the other earphone, and the test words were presented binaurally, in phase; (2) In the control listening condition, only a single set of background talkers, and the test words, were presented to a single ear. The stereophonic advantage, for 50% word intelligibility, ranged from 12 db with 1 background voice per channel to 5.5 db with 7 background voices per channel.
Minimum Axial Phase Velocity In Shells
Authors: Smith P. W.
Published: September 2005

A new approximate expression is proposed for the frequency of the point of minimum velocity in a cylindrical shell which is more accurate for higher values of the order number m (displacements ∼cosmθ). This and earlier approximations are compared with results of precise calculations. The transition between approximations is discussed.
Reflection of Low-Frequency Sonar Signals from a Smooth Ocean Bottom
Authors: Bucker H. P. , Whitney J. A. , Yee G. S. , Gardner R. R.
Published: September 2005

Measurements of the bottom-reflection losses for a low-frequency sonar signal (0.7–3.0 kc/sec) are reported for two areas off the California coast and for a third area in the Bering Sea. At all three areas, the bottom losses were large at small grazing angles. Comparisons are made between the measured values of bottom loss and those calculated for a plane sound wave reflecting from a layered model of the ocean sediments. The sediment model consists of a number of absorbing solid layers. Reasonable agreement is shown between the experimental and calculated values of bottom loss.
Deformation of an Exponential Pulse with a Finite Rise Time in the Region of Total Reflection
Authors: Duykers L. R. B.
Published: September 2005

The peak of an exponential pulse with a finite rise time is investigated in the region of total reflection. It is shown numerically that the peak is amplified in this region. The amplification seems to increase with a decreasing decay factor and or rise time of the initial pulse.
Theory of Signal Detectability: Deferred-Decision Theory
Authors: Birdsall T. G. , Roberts Richard A.
Published: September 2005

The theory of signal detectability is extended to include observation-decision procedures in which the available observation time is bounded. The special case of a simple signal hypothesis with stationary normal observation statistics is worked in detail. (“Signal known exactly in added white Gaussian noise” is an example of such a case.) The optimization is of the minimum average risk type, with constant cost of observation to facilitate comparison with work based on Wald's sequential analysis and comparison with fixed observation procedures. An unexpected result is that for large available observation lengths, approaching Wald's unbounded case, the optimization dictates that the primary improvement is in error performance rather than observation time.
Pseudorandom Signal-Correlation Methods of Underwater Acoustic Research I: Principles
Authors: Stewart James L. , Allen W. B. , Zarnowitz R. M. , Brandon M. K.
Published: September 2005

New methods of underwater acoustic-propagation research have been developed in which noiselike or pseudorandom signals, generated by shift-register encoders, are detected by correlation techniques. The principles and problems of three classes of experiments are discussed: (1) the signal received is crosscorrelated with a time-delayed and time-compressed replica of the transmitted signal; (2) two received signals are crosscorrelated and studied as a function of hydrophone separation; (3) the received signal is correlated with that received from a later repetition of the transmitted signal. It is shown theoretically that the results of the first class of experiments are different from and unpredictable from those obtained by employing the usual filtering and detection of impulsive or single-frequency signals. The severe problem arising from multipath interference in the second class of experiments, which is different for the multipath problem in the first class of experiments, is discussed and some solutions proposed. The essential identity of the second and third classes of experiments is discussed. A companion paper discusses the instrumentation for and execution of the experiments and presents some preliminary observations.
50-msec Electroacoustic Delay Line
Authors: Neubauer Werner G.
Published: September 2005

An acoustic delay line has been developed that delays an electrical signal in the order of 50 msec. The signal is transformed from electrical to acoustic energy, transmitted through air in a tube, and then transformed back to electrical energy. The delay is achieved by the time it takes sound to traverse the acoustic path between the acoustic source and the microphone. The delay line has a flat response to ±1.2 dB from 430 to 2000 cps. Its major components—acoustic driver, copper tubing, and capacitor microphone—are readily available and require little or no maintenance.
Message Procedures for Unfavorable Communication Conditions
Authors: Pollack Irwin
Published: September 2005

Several message procedures, designed to improve speech communications under extremely unfavorable speech-to-noise ratios, were examined. A message procedure based upon the informational principle of successive selections among a reduced number of alternatives was strikingly superior to a message procedure based upon the repetition of a single selection among a larger number of alternatives. Information, alone, is not the entire story because message diversity, without change of information, may produce nearly equivalent results.
Effect of “Aural Harmonics” on Frequency Discrimination
Authors: Henning G. Bruce
Published: September 2005

Frequency-discrimination performance was measured in two masking conditions: one in which “aural harmonics” were audible and one in which they were not. Frequency discrimination was identical in both conditions. This result, in conjunction with additional indirect evidence, indicates that aural harmonics have no effect on frequency discrimination.
Total Internal Reflection of Pulses in Stratified Media
Authors: Tolstoy I.
Published: September 2005

Under certain conditions discussed in this Letter, a delta-function type of pulse, subjected to total internal reflection at a turning point in a continuously stratified medium, will suffer an obvious shape change. Essentially, the pulse acquires a tail, due to the preferred retardation of the low-frequency components, corresponding to a frequency-independent phase change of π/2. Two turning points of this kind produce a π phase change: the pulse shape is reconstituted by the second turning point, although the sign is changed. These effects appear to be confirmed by records of small-charge explosions, obtained in the Mediterranean, which were made available to this writer by D. J. Parkes and R. Laval of the Saclant ASW Research Centre in La Spezia, Italy.
Nasalization of Vowels in Relation to Nasals
Authors: Hattori Shirô , Yamamoto Kengo , Fujimura Osamu
Published: September 2005

The principal characteristic features of nasalization of vowels are (1) a dull resonance around 250 cps, (2) an antiresonance at about 500 cps, (3) comparatively weak and diffuse components which fill the valleys between the formants.

Features (1) and (3) are commonly found also during the period of oral closure of nasal constants, (3) in this case being influenced by the antiresonance of the oral cavity. The feature (3) affected by “antiformants” carries information about the tongue position during oral closure. If the nasal passage is stopped at the nostrils when nasalized vowels are pronounced, features (1) and (3) disappear, and the frequency of selective attenuation (2) is lowered. Some French and Japanese nasalized vowels have been examined and interpreted, applying the results obtained in the research.
Focusing Ultrasonic System Applicable to Two-Dimensional Optical Beam Scanning and Laser Output Modulation
Authors: Flinchbaugh David E.
Published: September 2005

Recent interest in (1) the directional control of highly collimated light beams and (2) internal modulation of laser action has stimulated a variety of experiments. This paper reports on experiments utilizing a barium titanate ceramic transducer formed into an arc of a short section of right circular cylinder and radiating into a tetrachloroethylene-filled cell at 400 kc/sec. A helium-neon laser beam was used to examine the index of refraction gradients produced in the liquid and to illustrate the possible deflection patterns. When the beam traversed the cell near the focal line, circular scanning was observed, with maximum deflection angles of approximately ±1.0°. Linear scanning reached ±1.3°. Data describing the experimentally observed beam motion showed good agreement with a theoretical analysis of the complex acoustic field in this region. Deflections produced by pulse excitation of the transducer exceeded ±1.5°. Ruby laser spiking was modulated to follow the 400-kc/sec field, and in pulsed operation giant spikes were obtained, using the cell to control the Q of the optical resonator cavity. High-speed photographs of both the partial standing acoustic wave, the traveling shock waves, and the circular beam-deflection pattern were taken.
Reflection and Refraction of Sound by a Nonequilibrium Relaxing Medium
Authors: Wang Kuo Chang
Published: September 2005

The reflection and refraction of a plane sound wave by a nonequilibrium relaxing medium are examined. Since the medium is dissipative, Snell's law of refraction is modified depending not only on the properties of the media, but also on the angle of incidence. The amplitudes of the reflected and refracted waves are complex. Variations of both the angle and amplitude are analyzed and supplemented with calculations for different reaction rates and relative Mach numbers.
On the Measurement of Ultrasonic Velocity in Solids
Authors: Williams J. , Lamb J.
Published: September 2005

A new method has been developed for the accurate measurement of the velocity of compressional waves in solid specimens. This is based on the cancellation of a traveling wave train, which has undergone reflection at the ends of the specimen, by a second wave train launched from the same transducer. A description is given of the experimental system employed.

A correction must be made for the phase shift which occurs when the ultrasonic signal is reflected at the interface between specimen and transducer. A theoretical study of the effects of the transducer and coupling film shows that the correction is a function of the resonant frequency of the transducer and of the ratio of acoustic impedance of the transducer to that of the specimen.

The application of the correction enables the velocity of propagation to be determined to within 1 in 104.
Study of Noise and Hearing in Jute Weaving
Authors: Taylor W. , Pearson J. , Mair A. , Burns W.
Published: September 2005

A retrospective study of hearing in a female population exposed to weaving noise is described. The noise is believed to have remained substantially unaltered over periods of exposure ranging from less than 1–52 years. The deterioration of hearing due to noise has been assumed to be estimated by the difference between the recorded hearing level and the expected hearing level from other published presybcusis data. Patterns of deterioration of hearing are described for various audiometric frequencies. The most conspicuous feature is an initial deterioration in the first 10–15 years of exposure, followed by a period of about 10–15 years where deterioration attributable to noise is small. Thereafter, after 20–25 years of exposure, further deterioration occurs, especially marked at 2000 cps. The possible distribution of noise-induced threshold changes is briefly considered.
Stimulus-Identification Overlap in Learning to Identify Complex Sounds
Authors: Sidley Norman A. , Winograd Eugene , Bedarf Erwin W.
Published: September 2005

With a feedback method, two groups were taught to identify, by label, complex sounds. One group continued to hear the sound following response and during identification; the second group experienced a 1-sec delay between the sound and its label. Better learning and long-term retention characterized the group for which sound and label overlapped.
Acoustic Radiation from Isotropic Turbulence
Authors: Meecham W. C. , Ford G. W.
Published: September 2005

For low Mach number turbulence, Lighthill has given a result which expresses the acoustic radiation of turbulent fluid in terms of a fourth-rank velocity correlation. Through the use of the Navier-Stokes equation this relation can be put in terms of the space-time pressure correlation. For very large Reynolds number turbulence (in the inertial subrange where Kolmogoroff's similarity principles are valid) one can write this pressure correlation in terms of a function of a single variable. Since the space-time correlation of the pressure is needed one must take into account convective effects. This is done here by introducing a new Lagrangian type of correlation which is defined in such a way that a similarity argument can be applied without difficulty from the convective effects. Such convective effects then enter only through negligible Doppler shifts. Using this similarity result and Lighthill's formulation, one obtains the acoustic self-noise power spectrum for the turbulence. The spectrum is proportional to ω−7/2M21/2 for high frequencies (ω≫c0M/L) where ω is the acoustic angular frequency, M is the turbulence Mach number, c0 is the velocity of sound in the fluid, and L is the size of the large-scale turbulent eddies. The spectrum at the high-frequency end is universal, that is it is independent of the details of the driving mechanism. Furthermore the spectrum is proportional to ω4M3 at the low-frequency end and depends on the large scale eddies there. The similarity hypothesis made here for the special Lagrangian type of space-time correlation is of interest in itself in turbulence theory. It is difficult to check this hypothesis directly; however, a measurement of the acoustic power spectrum offers an interesting indirect check on the hypothesis.
Ray-Theory Solution of the Problem of Propagation of Explosive Sound in a Layered Liquid
Authors: Pekeris Chaim L. , Longman Ivor M.
Published: September 2005

The problem of propagation of explosive sound in a layered liquid is formulated operationally, and an exact solution is derived based on ray theory. The contribution of each ray at a given time is expressed by a single definite integral taken over a fixed finite range. With the aid of an electronic computer the pressure-field was evaluated both for the case of a slow-speed bottom and for the case of a high-speed bottom. It was found that for a Heaviside unit pulse and a high-speed bottom the pressure becomes logarithmically infinite at the time of arrival of the totally reflected wave. For a high-speed bottom, the pressure pulse at large ranges, as computed by the ray theory, exhibits the well-known features, first observed by Ewing and Worzel and later deduced from the normal-mode theory, of a long-period ground-wave followed by a high-frequency dispersive water-wave. We have found, furthermore, that at large ranges sufficient accuracy can be obtained by retaining only the contributions from a group of the last arriving quadruplets of rays. With this approximation it becomes feasible to use ray theory for the evaluation of the pressure field even at large ranges.
Temporal Effects in Simultaneous Masking and Loudness
Authors: Zwicker Eberhard
Published: September 2005

The intention of the research described was twofold. One purpose was to investigate the difference between threshold curves for tones masked by bands of noise and the corresponding displacement curves obtained from models of the basilar membrane. The second object of investigation was the behavior of a strange masking transient which indicates that masking of a short signal pulse by a longer masker burst is stronger at the beginning of the masker burst than later under certain circumstances, but that under other conditions masking remains constant during the total duration of the masker. The threshold of signal pulses masked by masker bursts was measured as a function of different variables such as bandwidth and center frequency of masker, delay between onset of masker and onset of signal, duration of signal, and spectrum shape of masker. The results, especially those obtained when white noise with a frequency gap was the masker, lead to the hypothesis that the masking excitation appears almost instantaneously. This hypothesis was tested and accepted on the basis of loudness judgments comparing equally long tone pulses and white-noise pulses of very short and long duration. The conclusion that excitation occurs almost instantaneously, taken together with the known relationship between the masking effect of white noise and that of narrow-band noise, is construed to mean that a complex spatial inhibition in the nervous system may not be responsible for the narrow sensitivity curve; in fact, a sharp mechanical filter could account for the findings.
Correlation of Ambient Noise in the Ocean
Authors: Arase Elizabeth M. , Arase T.
Published: September 2005

Correlation measurements of ambient sea noise have been made with pairs of vertical hydrophones near the ocean bottom at a depth of about 14 500 ft. Typical auto and space-time crosscorrelations are shown at 500 cps for sea state 5. The time delay corresponding to the maximum value of the space time correlation was measured in six frequency bands, with center frequencies of 125, 180, 250, 400, 500, and 800 cps, and is given as a function of hydrophone separation. These curves are almost straight lines. The time delays correspond to steering angles. Maximum correlation is obtained at increasing elevation angles as the frequency increases.
Ambiguity Diagram for Linear FM Sonar
Authors: Russo Donato M. , Bartberger Charles L.
Published: September 2005

Ambiguity diagrams are useful in estimating the range and Doppler resolution of radar and sonar systems in which the returning echo is correlated with a stored replica of the transmitted pulse. In the conventional approach for linear FM pulses, the equations are simplified by regarding the Doppler shift as a simple frequency translation, applied equally to all frequencies within the bandwidth. This approximation, while satisfactory for most radar applications, is in general not valid for sonar pulses. In this paper, the general equations are derived for the correlation function of a linear FM pulse, taking into account the effect o the Doppler shift on both the frequency sweep rate and the carrier frequency. An ideal point target is assumed. Computations based on a close approximation to the general case have been made for four 1-sec pulses with carrier frequencies of 10 and 20 kc/sec and sweep rates of 50 and 600 cps2. The ambiguity diagrams for the low sweep rate are almost identical with those of the “radar case,” whereas the diagrams for the high sweep rate are greatly shortened. A criterion for the applicability of the radar approximation is developed.
Experiments on the Four-Eared Man
Authors: Moray Neville , Bates A. , Barnett T.
Published: September 2005

Subjects were required to listen to messages consisting of 1, 2, 3, or 4 letters of the alphabet over each of 1, 2, 3, or 4 channels. It was found that increasing the number of channels above 2 had a markedly deleterious effect upon recall of the messages, 2 letters over each of four channels being less well recalled than 4 letters over each of two channels. In a second experiment, it was found that, providing only one channel was required in recall, and this one was indicated by a light immediately after the stimuli had been presented, then the decrement could be largely offset and the total number of signals stored held constant at about 8 regardless of how many channels were used. However, if the letters had to be recalled in exactly the correct order in which they arrived, performance dropped to almost zero. The results are discussed in terms of the channel capacity of the nervous system and in relation to corresponding findings in other sense modalities.
Narrow-Band Noise and Tones as Signals in Binaural Detection
Authors: Rilling Mark E. , Jeffress Lloyd A.
Published: September 2005

Two experiments compare the effect of fixed and random phase relations between masker and signal in binaural masking. In Experiment 1, a comparison made between interaural time delay and phase shift of a narrow-band-noise signal where the phase relations between the signal and the masker are random. The signal is Gaussian noise passed through a 50-cps filter centered at 500 cps. The masker is broad-band noise from a second noise generator. The conditions using noise as the signal are compared with the same conditions in which a 500-cps tone is the signal. A two-interval, forced-choice procedure was used to obtain MLD's (masking-level differences). The MLD increases rapidly as the interaural phase shift or interaural time delay increases. The MLD's for corresponding phase-shift and time-delay conditions are approximately the same for tonal and noise signals. In Experiment 2, a single noise generator is used and a comparison is made between N0 S0 and N0 Sπ for various phase relations between the narrow-band-noise signal and the masker. The noise signal has the same bandwidth as in Experiment 1. The results show a substantial dependence of the MLD's on the signal-noise phase relation.
Efficiency of a Linear Array of Point Sources with Linear Phase Variation
Authors: Thiessen G. J. , Embleton T. F. W.
Published: September 2005

The radiation efficiency of a linear array of point sources with linear phase variation is solved using different approximations for different ranges of the phase parameter. The results are compared with experimental results on small models and also on full-scale suction rolls in paper mills with different drilling patterns. The experiments agree quite closely with theory and indicate that a noise reduction of 15 to 30 db can be obtained by the choice of a substitute drilling pattern that can easily be drilled by multiple spindle machines. Design charts for choosing and evaluating drilling patterns are given.
Note on the Virtual Mass for a Panel in an Infinite Baffle
Authors: Pretlove A. J.
Published: September 2005

This paper considers the reactive component, as distinct from the resistive or energy-radiating component, of the free-field acoustic load on a panel vibrating in an infinite baffle. A finite element technique is used to evaluate the integrals numerically for a simply supported panel vibrating in its fundamental mode. Results have been obtained for panel aspect ratios between 0.1 and 1.0 and for acoustic-wavelength/plate-length ratios between 1.5 and ∞. For a specific panel, it is shown that this component of the radiation load on the panel reduces the fundamental natural frequency by 1.8%. For lighter panels, this effect is proportionately increased.
Deflection of a Particle Moving along an Infinite String Resting on an Elastic Foundation
Authors: Wilms E. V. , Stippes M.
Published: September 2005

The deflection of a point mass moving along an infinitely long, elastically supported string is determined using the method of characteristics. The mass is subjected to a time-varying force perpendicular to the length of the string. If the elastic support is small, explicit solutions may be obtained.
Marine Sediment Attenuation and Ocean-Bottom-Reflected Sound
Authors: Cole B. F.
Published: September 2005

The attenuation of sound in marine sediments is shown to depend on the first power of the frequency for a range of 100–1000 cps, and the relation between sediment attenuation and ocean-bottom reflectivity is discussed. The reflection process is approximated by a three-layer fluid model, with attenuation in the second and third layers. Theoretical reflection coefficients are calculated, considering the sediment attenuation as proportional to the one-half, first, and second powers of the frequency for comparison with measured coefficients. For the range of frequencies considered, the first-power frequency-attenuation law in the sediments is consistent with the observed dependence of the ocean-bottom reflectivity.
Ultrasonic Absorption in Liquids. I
Authors: Mokhtar M. , Youssef H.
Published: September 2005

The absorption of ultrasonic waves is measured for five nonassociated and five associated liquids at different temperatures extending between their freezing and boiling points. The absorption is measured by an electrodynamic balance specially developed for this purpose and explained in a previous issue. No relaxational processes were detected by varying the temperature. The thermal coefficient of absorption (1/α) (∂α/∂t) is not constant for any liquid, but it varies with temperature. Moreover, its behavior changes from one liquid to another. Such behavior, if plotted on normalized scale of temperature (between freezing and boiling points) instead of ordinary scale, brings all nonassociated liquids to one common line given by (1/α) (∂α/∂t) = c1tN12, and all associated liquids to another common line given by (1/α) (∂α/∂t) = c2tN+c3, where tN is the normalized temperature. The constants c1, c2, c3 do not depend on the nature of any particular liquid used. Thus these equations may be considered as “reduced equations of absorption.”
Some Results in Automatic Speech Segmentation Using Wide-Band Filtering and Subtraction
Authors: Tufts D. , Mayhew D. , Dostie G. , Smith A.
Published: September 2005

The experimental results of applying a simple method for automatic segmentation of speech are presented. The performance of the segmentor is that it provides boundary indications for elementary speech sounds with more than 75% reliability, measured over the utterances of four male speakers. The criterion of performance is that the segmentor should automatically provide in real time the boundaries between elementary speech sounds (i.e., phonemes) that are the same as those obtained in the analysis of a sonogram of the utterance by a trained human observer. The main source of error in the present segmentor is not incorrect boundaries, but extra boundaries inserted between correct boundaries. This fact makes the effective accuracy of the segmentor, for the purpose of automatic recognition of phonemes, better than its 75%–80% absolute accuracy.
Comments on “Axisymmetric Vibrations of Thin Elastic Shells” [C. N. DeSilva and G. E. Tersteeg, J. Acoust. Soc. Am. 36, 666–672 (1964)]
Authors: Hu William C. L.
Published: September 2005

In a recent paper, DeSilva and Tersteeg [J. Acoust. Soc. Am. 36, 666–672 (1964)] presented a membrane theory for axisymmetric vibrations of thin shells of revolution, in which the effect of longitudinal inertia was neglected. Numerical comparisons are presented in this discussion to show that the effect of longitudinal inertia is not negligible in axisymmetric vibration of nonshallow shells. For vibrations of shallow shells, the longitudinal inertia effect is small, but the bending effect becomes important.
On the Attenuation of Finite Amplitude Waves in a Liquid
Authors: Rudnick Isadore
Published: September 2005

An expression is obtained for the rate of attenuation of large amplitude waves of stable form propagated in a liquid whose attenuation varies as the square of the frequency. Calculations are presented for several liquids and comparison made with recent published data.
Natural Frequencies of Closed Spherical Shells
Authors: Wilkinson J. P.
Published: September 2005

Equations are presented for the natural frequencies of free vibration of closed elastic spherical shells. They are derived from a theory of shells that includes the effects of transverse, shear, and rotatory inertia. It is shown that five branches appear in the frequency spectrum, whereas only three are known to be predicted by the classical bending theory of shells.
Possible Effects of Sea-Surface or Volume Reverberations on Low-Frequency Deep-Water Bottom-Reverberation Measurements
Authors: Mackenzie K. V.
Published: September 2005

Computations of sea-surface and volume reverberations are presented to demonstrate that these reverberation contributions are at least 10 dB below the observed bottom reverberation of Mackenzie [J. Acoust. Soc. Am. 33, 1498–1504 (1961)] and consequently cause no ambiguity in Mackenzie's analysis of bottom reverberation, as suggested by Goodman [J. Acoust. Soc. Am. 37, 174(L) (1965)].
Comments on “Influence of Sound upon Local Heat Transfer from a Cylinder” [P. D. Richardson, J. Acoust. Soc. Am. 36, 2323–2327 (1964)]
Authors: Fand R. M.
Published: September 2005

In a recent paper [J. Acoust. Soc. Am. 36, 2323–2327 (1964)], P. D. Richardson presents experimental data on the heat transfer from and boundary-lager flow near a heated horizontal cylinder in the presence of horizontal, transverse, stationary sound fields. On the basis of these data, Richardson concludes that the so-called “critical” sound-pressure level may be important in engineering applications but has no intrinsic fluid-mechanical significance. The present commentary reevaluates Richardson's contribution in the light of previously published work on this subject. It is shown, in particular, that, although Richardson's data—all of which were taken at subcritical sound-pressure levels—cannot be used to draw firm conclusions concerning the existence of a critical sound-pressure level, these data tend to confirm—rather than refute—the previously demonstrated fluid-mechanical significance of the critical sound-pressure level.
On AX and ABX Limens
Authors: Pierce J. R. , Gilbert E. N.
Published: September 2005

Rosenblith and Stevens obtained larger frequency limen by the ABX method than by the AX method. The ratio of the limens is here calculated on the assumption that there is a statistical variation in the physiological or psychological response to a given stimulus. The ratio of limens is 2.12 for a Gaussian distribution of response and 2.14 for a uniform distribution. The model fits data for subject KNS well, but not the data for subject WAR.
Study of Methods for Estimating Loudness
Authors: Corliss Edith L. R. , Winzer George E.
Published: September 2005

The methods for computing loudness developed by Zwicker [Acustica 2, Akust. Beih. 1, 125–133 (1952); Acustica 8, Akust. Beih. 1, 237–258 (1958)] and Stevens [J. Acoust. Sac. Am. 28, 807–832 (1956); 11, 1577–1585 (1961)] were applied to several complex sounds encountered in our work on architectural acoustics. The loudnesses computed on the basis of Stevens' method did not agree closely with the loudnesses computed by Zwicker's method, and the results obtained by using the two methods were not related to one another in any consistent way. Further, studies with subjects showed that both sets of computations gave results at variance with the responses of the subjects. Investigation of the loudness-versus-frequency contours for our subjects showed closer conformity to the Fletcher and Munson [J. Acoust. Soc. Am. 5, 82–108 (1933)] data than to the more recent equal-loudness contour reported by the National Physical Laboratory [Brit. Std. 3383, Brit. Stds. Inst. (1961)], the functions reported by Zwicker, or the band-pressure levels that form the basis for the loudness weighting in Stevens' method. However, this feature does not suffice to account for the discrepancies observed.
Speed of Sound in Fluid Parahydrogen
Authors: Younglove B. A.
Published: September 2005

This paper presents measurements of speed of sound in compressed fluid parahydrogen. The measurements cover temperatures from 15 to 100°K and pressures to 300 atm. Calculations based on previous pressure, density, and temperature measurements of this laboratory provide the density corresponding to each experimental temperature and pressure. These measurements complement previous thermodynamic data on parahydrogen of this laboratory, giving extensive verification of sound-speed calculations based on those measurements. Prior to this work, no known experimental speeds had been determined for compressed liquid parahydrogen above 21°K.
Generation and Synthesis of Tone Complexes
Authors: Hickman Aubrey T.
Published: September 2005

This account discusses the difficulties met in designing and constructing an electronic apparatus for generating fundamentals and harmonics up to and including the sixth for a music research project concerned with timbre. The problem of adequately suppressing lower-order harmonics and fundamental when upper-order harmonics only are required at the output is shown to be related to certain aspects of auditory behavior. A solution followed when a design compatible with these aspects had been found.
Compensation Technique for Active Damping Improvement
Authors: Lawther J. M. , Rockwell T. H.
Published: September 2005

The stability analysis previously developed for active feedback dampers has been extended to show that damping effectiveness may be greatly enhanced through the use of properly designed networks in the feedback path.
Ultrasonic Absorption in Aqueous Solutions of High-Molecular-Weight Polysaccharides
Authors: Hawley S. A. , Kessler L. W. , Dunn Floyd
Published: September 2005

The ultrasonic amplitude absorption coefficient has been determined in aqueous solutions of four molecular weights (73 000, 186 000, 370 000, and 2 000 000) of dextran, a linear α (1 → 6) anhydroglucose polysaccharide of biological origin, over the frequency range 3–69 Mc/sec at 22°C. It is found that the concentrationfree absorption spectrum exhibits a remarkable similarity to that of aqueous solutions of beef hemoglobin. The latter finding leads to the conclusion that ultrasonic absorption in tissues is not dominated exclusively by constituent proteins and that the contribution to such absorption by molecular structures lacking tertiary configurations may be considerable.
Intensity and Duration of Noise Exposure and Temporary Threshold Shifts
Authors: Spieth Walter , Trittipoe W. J.
Published: September 2005

What is the “trading relationship” between intensity and duration of exposures to loud sound in producing a given magnitude of temporary threshold shift (TTS)? Examination of the literature led to the hypothesis that duration is about twice as important as intensity: Two exposures should produce the same TTS if one exposure were one-fourth the sound level (6 db less) and twice the duration of the other exposure. The hypothesis was tested on 12 human ears with thermal noise exposures ranging from 130 db SPL for 1 min to 94 db SPL for 64 min. In this series each doubling of duration was associated with a fourfold or 6 db decrease in sound level. TTS was measured at 2000, 4000, 6000, and 8000 cps. If the hypothesis were true, all exposures should have produced the same TTS. Actually the obtained average TTS, 5 min after exposure, described an inverted U-shaped function when plotted by increasing duration of exposure. The conditions from 118 db for 4 min through 100 db for 32 min produced roughly similar amounts of TTS, while the other conditions produced substantially less TTS. The shapes of the recovery curves differed systematically: At 4000 cps, the TTSs 20 sec after exposure were in perfect rank-order agreement with intensity of exposure, while from about 2 min to 10 min the inverted-U rank order was apparent.