bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient Acoustic Parameters for Speaker Recognition
Authors: Wolf Jared J.
Published: October 2005

In a scheme for the mechanical recognition of speakers, it is desirable to use acoustic parameters that are closely related to voice characteristics that distinguish speakers. This paper describes an investigation of an efficient approach to selecting such parameters, which are movitated by known relations between the voice signal and vocal-tract shapes and gestures. Rather than general measurements over the extent of an utterance, only significant features of selected segments are used. A simulation of a speaker recognition system was performed by manually locating speech events within utterances and using parameters measured at these locations to classify the speakers. Useful parameters were found in fundamental frequency, features of vowel and nasal consonant spectra, estimation of glottal source spectrum slope, word duration, and voice onset time. These parameters were tested in speaker recognition paradigms using simple linear classification procedures. When only 17 such parameters were used, no errors were made in speaker identification from a set of 21 adult male speakers. Under the same conditions, speaker verification errors of the order of 2% were also obtained.
Significance of Resistance Measurements in the Scala Media
Authors: Cern Y. , Fischler H.
Published: October 2005

Resistance measurements of the cochlear membranes are analyzed regarding the effective length of the cochlea actually sensed. It is shown that only short segments are represented by the measurements, as confirmed by experimental results. It is asserted that both the longitudinal and transverse dimensions must be considered simultaneously in cochlear modeling, as facilitated by a transmission line or core conductor approach.
Comment on “Intracochlear Potential Recorded with Micropipets. III. Relation of Cochlear Microphonic Potential to Stapes Velocity” [T. F. Weiss, W. T. Peake, and H. S. Sohmer, J. Acoust. Soc. Amer. 50, 602–615 (1971)[
Authors: Price G. Richard
Published: October 2005

It is argued that the approximately constant relationship of cochlear microphonic output to stapes velocity noted by Weiss, Peake, and Sohmer [J. Acoust. Soc. Amer. 50, 602–615 (1971)[ is probably a function of a bias introduced by the choice of electrode location, i.e., the bone near the round window. Based on recordings from the round window, cochlear microphonic output rises about 20 dB between 100 Hz and 10 kHz if stapes velocity is held constant.
Relationship Between Zero-Crossing Measurements for Speech Analysis and Recognition
Authors: Ito M. R.
Published: October 2005

Three types of zero-crossing measurements—(i) average zero-crossing rate, (2) density of time intervals between zero-crossings, and (3) excess-threshold duration—are related theoretically. It is shown that measurement types 1 and 3 can be derived from the type 2 measurement. Measurement types 1 and 3 cannot be directly related, but it is shown that the type 2 measurement can be derived from the type 3 measurement.
Theoretical and Experimental Studies of the Focus of Sonic Booms
Authors: Wanner Jean-Claude L. , Vallee Jacques , Vivier Claude , Thery Claude
Published: October 2005

Knowledge of sonic booms produced by airplanes in steady rectilinear flight is now sufficient to allow for good predictions of the phenomena. In order to improve the knowledge of the effects of accelerations and curvatures of the flight path, the French Working Group on sonic booms has undertaken a set of theoretical and experimental studies on that subject. Theoretical studies of the propagation of the shock waves have helped identify the different cases of focus (linear acceleration, turn, pushover) and superfocus (entry to turn). They have also shown that, after measurement of the actual characteristics of the atmosphere, it was possible to guide an airplane in order to produce focusing in a measurement zone of realistic size. During the four experimental exercises of “Operation Jericho” the accuracy of prediction of propagation and guidance of the airplane has shown that focus factors are higher than those predicted.
Interferometry for Underwater Vibrational Measurements
Authors: Frodyma F. J. , Andrews F. A.
Published: October 2005

A method is described for measuring arbitrary vibrational displacements of a transducer in water. A Michelson interferometer with a laser as a light source is utilized. The minimum displacements that could be obtained are presented. The bandwidth and susceptibility to noise of the system without vibration isolation are discussed.
Generation of Combustion Noise
Authors: Arnold James S.
Published: October 2005

An analytical description is presented for the generation of noise in burning fuel-air mixtures. Fluctuating pressure (noise) is shown to result when the heat release rate of the mixture passing through the reaction zone is variable with time. Experimental evidence in support of this view is presented and referenced from the literatures of acoustics and combustion. Several illustrative examples from common experience are pointed out. Premixed and diffusion flames of gas and liquid fuels are considered, and the role of flame and mixture turbulence in causing a varying heat release rate and noise is noted. The possibility appears to exist for substantially reducing the noise output of large combustion systems (jet engine, for example) by more effective control of the flame configuration and stability.
Scattering of Elastic Waves by Moving Objects
Authors: Aboudi Jacob , Censor Dan
Published: October 2005

It is shown that simple elastic media in motion exhibit new properties, owing to the effective compressional and shear wave velocities produced by the motion. Presently, we consider scattering of a compressional plane wave by (1) a half-space moving parallel to the interface and (2) a cylinder moving along its axis. In both cases the assumed boundary conditions correspond to good contact at the interface. Computational results are given for the scattering amplitudes as a function of velocity and angle of incidence.
Transient Acoustical Sources in an Idealized Jet
Authors: Graham E. W. , Graham B. B.
Published: October 2005

The transmission of acoustic disturbances from the interior of the jet through the mean velocity profile and into the farfield is studied in detail. The noise generator is taken to be a sequence of transient acoustical point sources traveling with the local fluid in the idealized jet. The idealized jet is two-dimensional, and extends to infinity upstream and downstream with velocity profile independent of streamwise position. For the limited set of examples considered the following conclusions apply: (1) Velocity profile has a large effect on the magnitude of the noise radiated to the farfield. (2) Much of the farfield noise, especially at low Strouhal numbers, originates not as true waves but in the form of acoustical disturbances within the jet which are not radiating energy. (3) At subsonic velocities, the characteristic lobes appearing in a polar plot of farfield mean-square pressure approach the downstream axis as frequency decreases. This somewhat resembles experimental trends, but many other factors must be considered before a valid comparison can be made.
Theoretical Analysis of Rough-Surface Shadowing from Point-Source Radiation
Authors: Hardin Jay C.
Published: October 2005

The shadowing function, defined as the probability that a point on a rough surface will be illuminated by radiation from a source at fixed height above the surface, is considered. An exact expression for this probability is derived and evaluated approximately when the surface elevation is a normal random process. The effect of surface correlation is considered and shown to be appreciable. Several numerical computations of the shadowing function are presented.
The Ray Sweep-Out Method
Authors: Bucker H. P.
Published: October 2005

To calculate the ray intensity field at a point (a receiver point) in range and depth, all significant ray paths from the source to the receiver must be found. When there are a large number of receiver points, it is desirable to use a method in which all receiver points are considered as the rays are tested to find those that travel from the source to a receiver. This paper describes a simple method for finding all ray arrivals during a single sweep out of the source beam pattern and at the same time calculating the total ray intensity field at the receiver points.
Acoustic Cavitation in Helium, Nitrogen, and Water at 10 kHz
Authors: Neppiras E. A. , Finch R. D.
Published: October 2005

Observations of acoustic cavitation have been in helium I and II using an extensional-mode vibrator capable of very high intensities at 10 kHz. Remote monitoring of the drive oscillatory velocity was achieved. In helium I clouds of small vapor bubbles were visible, as well as larger bubbles near the expected radial resonance size. For comparison, observations were also made using two other normal liquids—nitrogen and water—at temperatures near their boiling points. In helium II observation of acoustic streaming with emission of white noise suggested the presence of even smaller vapor bubbles. A strong subharmonic signal with low threshold excitation has not been fully explained.
The W.K.B. Approximation, Turning Points, and the Measurement of Phase Velocities
Authors: Tolstoy Ivan
Published: October 2005

The conditions of validity of the W.K.B. approximation in geoacoustic problems are investigated; of particular interest here is the behavior of acoustic-gravity waves in the earth's thermosphere. A conclusion of some general significance is that great care must be exercised in interpreting vertical phase velocity measurements: thus, whereas W.K.B. methods and intuitive arguments suggest an infinite vertical phase velocity at turning points, exact solutions show that this is not necessarily the case. This has obvious practical implications for one's efforts at understanding the structure of a stratified medium by means of phase velocity measurements, particularly where these measurements are made near a turning point.
Acoustic Radiation from Two Spheroids
Authors: Van Buren A. L. , King B. J.
Published: October 2005

The acoustic radiation from two spheroids whose surface normal velocity distributions are specified is calculated using a Green's function approach. To simplify the analysis only axially symmetrical problems are considered. The necessary Green's function is expanded in spheroidal wave functions about both spheroids. The unknown expansion coefficients are determined from the boundary condition that the normal derivative vanishes over both surfaces. An addition theorem which expresses spheroidal wave functions in one coordinate system in terms of spheroidal wave functions in another coordinate system was developed to facilitate application of this boundary condition. Numerical results for several different two-spheroid configurations and velocity distributions are presented and discussed. The straightforward extension to nonaxisymmetrical problems and to more than two spheroids is also discussed.
Experimental Determination of Ultrasonic Wave Velocities in Plastics, Elastomers, and Syntactic Foam as a Function of Temperature
Authors: Folds D. L.
Published: October 2005

The sound velocity of 16 plastics, two low-sound-velocity elastomers, and three types of syntactic foam have been measured at a frequency of 500 kHz in the temperature range 0°–30°C. Sound velocity values in the range 872–2836 m/sec and thermal coefficient of sound velocity in the range −0.93 to −9.55 m/sec°C are reported.
Coupling of Longitudinal and Transverse Motions of a Flexible Cable in a Uniform Flow Field
Authors: Genin Joseph , Citron Stephen J. , Huffman Ronald R.
Published: October 2005

A nonlinear mathematical model of the dynamics of an extensible cable in a uniform flow field is used to study the degree of coupling between longitudinal and transverse modes of motion. The various coupling effects are elucidated, and through use of numerical solutions of the model, the primary coupling effect is shown to be the tension variation due to centripetal acceleration of the cable.
Sound Absorption in the Pacific Ocean
Authors: Bezdek H. F.
Published: October 2005

The absorption of sound in the Pacific Ocean, at a nominal frequency of 75 kHz, was measured over a horizontal path at depths of 910 and 3350 m. The results are 20.0±1.5 dB/km and 13.5±1.5 dB/km, respectively, which may be compared to values of 27.3 dB/km and 22.7 dB/km extrapolated from the empirical relation of Schulkin and Marsh. Evidently, the useful range of this relation is severely limited. In addition, the effect of pressure may be greater than previously suspected.
Enhancement of the Mechanosensivity of Hair Cells of the Lateral-Line Organs by Environmental Potassium Ions
Authors: Hashimoto Toru , Katsuki Yasuji
Published: October 2005

The cochlear hair cell has a remarkably high sensitivity to the displacement of the basilar membrane of the inner ear. However, the detailed mechanism of the receptor process, especially for the high sensitivity, has not been fully established. The present article is concerned with the enhancement of the mechanosensitivity of the receptor hair cells of the lateral-line organ of aquatic animals by the environmental potassium ions. The potassium ion on the receptor surface of the lateral-line organ, the free standing neuromast, modified the receptor sensitivity to vibratory mechanostimuli. Studies on the free neuromast rather than on the canal neuromast may better contribute to the understanding of the excitation mechanism of the cochlear hair cell.
Detection of Tones in the Absence of External Masking Noise. I. Effects of Signal Intensity and Signal Frequency
Authors: Watson Charles S. , Franks John R. , Hood Donald C.
Published: October 2005

Twelve highly trained listeners detected tonal signals in the absence of external masking noise. The signals were 150 msec long and ranged from 125 to 4000 Hz. Fitted psychometric functions were steeper at high than at low frequencies requiring between 3- and 8-dB increase in signal level to raise performance from 60% to 95% correct. The signal levels that yield 76% correct detection in a two-alternative, forced-choice psychophysical procedure were in good agreement with the International Standards Organization's recommended values of audiometric zero. The results are consistent with a limitation imposed on auditory sensitivity by a “system noise” which is composed of the noise in the ear canal at low frequencies, and a low-level (−11 dB SPL) component of unspecified origin at medium and high frequencies. No qualitative differences were observed between detection without external masking noise and previous data on the detection of tones masked by noise.
A Theory of Central Auditory Masking and Its Partial Validation
Authors: Zwislocki J. J.
Published: October 2005

A quantitative psychophysiological theory of central masking is developed and partially validated by means of psychophysiological comparisons. The theory assumes constant signal-to-noise ratio in the physiological domain for constant signal detectability, partial linear summation of dichotic inputs, and a direct proportionality between driven neural activity and sound intensity at near-threshold intensities. All assumptions are based on psychophysical and physiological evidence independent of central masking. The theory is shown to predict accurately single-unit characteristics of the auditory nerve and of primary-like populations in the cochlear nuclei and the superior olive. Validating comparisons between calculated and empirical results are made in time, frequency, and intensity domains, for steady-state and transient stimuli.
Ultrasonic Exposure Thresholds for Changes in Cells and Tissues
Authors: Hill C. R.
Published: October 2005

The first part of this paper reports an experimental investigation of some parameters that control the occurrence of biologically effective cavitation-type phenomena in the frequency region 0.25 4 MHz. The experimental criterion by which “cavitation” is recognized here is the simultaneous occurrence of degradation of DNA in aqueous solution, liberation of free I2 from KI solution, and generation of half-order subharmonic. The intensity threshold for cavitation rises with frequency from 0.14 to 17.5 W cm−2 (spatial peak) in the above frequency range. Pulse duration and duty factor are also found to be determining parameters, with cavitation activity reducing to zero when values of both parameters are sufficiently low. A strong positive correlation between ambient pressure and intensity threshold has also been determined. On the basis of observations of the levels of scattered half-order subharmonic signals from various media, no evidence could be found for cavitation activity in sonicated mammalian tissues, although such activity could be detected in a wide range of liquids. The second part of the paper consists of a review, conducted in the light of the above results, of published experimental data relating to the existence and values of exposure thresholds for possible nonthermal, noncavitational mechanisms of action of ultrasound in living cells and tissues.
On the Development of the Critical Band
Authors: Zwicker Eberhard , Fastl Hugo
Published: October 2005

Temporal effects in masking experiments, which have been interpreted to show a development of the critical band, are reconsidered. In the view of the present authors, such a development does not occur. The measured effects can rather be attributed to spectral effects and/or the overshoot phenomenon.
Sound Radiated by Turbulent Flow off a Rigid Half-Plane as Obtained from a Wavevector Spectrum of Hydrodynamic Pressure
Authors: Chase David M.
Published: October 2005

The spectrum and intensity are calculated for radiated pressure generated from turbulent flow by diffraction at the edge of a rigid half-plane. The formulation relates the radiated spectrum to the local wavevector-frequency spectral density of pressure near the edge in a plane bounding the flow and is based on the notion of a hydrodynamic pressure field driving a contiguous sound field. In the half-plane extension, the pressure diffracted by the rigid surface vanishes, and the spectrum of the driving hydrodynamic pressure may be approximated accordingly. Results are obtained without explicit reference to fluctuating velocity when the (low Mach number) flow is regarded as confined to one side of the half plane and a model suitable for turbulent-boundary-layer wall pressure is used for the driving spectrum. Results are also obtained from a model suitable for pressure in the inertial subrange of homogeneous turbulence. From the wall-pressure model, the frequency spectrum of radiated pressure, for ωδ/U⩾5 cosα, where U denotes flow speed, δ boundary-layer thickness (large-eddy scale), and α the angle of flow relative to the edge normal, is found to vary as ω−2, U6, and for fixed radiating edge length, cos2α. The corresponding frequency-integrated intensity varies as U5 and cosα. Pertinence of results for a rigid surface to typical water-loaded, flexible surfaces is suggested. Experimental results are interpreted on the basis of the formulation.
Comment on “An Intensity Differential Equation in Ray Acoustics” [L. P. Solomon and L. Armijo, J. Acoust. Soc. Amer. 50, 960–963 (1971)]
Authors: MacKinnon Robert F.
Published: October 2005

The present letter demonstrates an error in boundary conditions at a reflecting surface.
Comments on “Nonlinear Oscillations of Laminated Specially Orthotropic Plates with Clamped and Simply Supported Edges” [C.- Wu and J. R. Vinson, J. Acoust. Soc. Amer. 49, 1561–1567 (1971)]
Authors: Laura Patricio A. , Maurizi Mario J.
Published: October 2005

Recent research efforts are referenced in the present letter.
Scattering of Sound by Air Bubbles in Water
Authors: Mole L. A. , Hunter J. L. , Davenport J. M.
Published: October 2005

The scattering strength of air bubbles in water has been determined experimentally at frequencies of 1 and 5 MHz. The bubble size and sound frequencies represent the short wavelength limit, where ka > 1. By scanning the sound fields with a PZT transducer of 1 mm radius, angular distributions have been obtained out to an angle of 35° with and without the scatterers present. The results agree well with recent scattering measurements in suspensions and also with scattering theory.
Acoustic Field of Circular Plane Piston in Limits of Short Wavelength or Large Radius
Authors: Rogers Peter H. , Williams A. O.
Published: October 2005

The acoustic beam of a circular plane piston (radius a) is analyzed as it approaches either the short-wavelength limit (SWL) or the large-radius limit (LRL). Using a new expression for the beam, we show that with no absorption the SWL would be a cylindrically collimated beam, with radius a, of plane waves. If absorptive effects are minor, the chief deviations during approach to the SWL occur in two decreasing volumes, a horn-shaped paraxial region and a cylindrical shell of mean radius a. One consequence is that any second harmonic, self-generated in the beam, approaches its own SWL more rapidly than does the first harmonic. Approach to the LRL yields a known paradox: Even the piston's nearfield need not approach a uniform plane wave. We show that the presence of absorption does make the LRL a plane wave and that in the absence of absorption there is a valid reason for the paradox: The piston beam must have a unique axis of cylindrical symmetry; an unbounded plane wave cannot.
Free Flexural Vibrations of an Elliptical Plate with Simply Supported Edge
Authors: Sato Kenzo
Published: October 2005

In the present paper, the free flexural vibrations of an elliptical plate with simply supported edge are considered by the use of Mathieu functions and modified Mathieu functions which are solutions of the differential equation of motion. The boundary conditions of simple support of an elliptical plate are obtained and the frequency equation of symmetrical vibrations about both axes is lead from those boundary conditions. The nondimensional frequencies calculated numerically for the first five normal modes of vibrations are shown in graphs for various eccentricities.
Comparison of Measured and Calculated Normal-Mode Amplitude Functions for Acoustic Waves in Shallow Water
Authors: Ferris Raymond H.
Published: October 2005

Wave theory predicts that acoustic propagation in bounded media may occur in discrete normal modes. Each modal field has a distinctive pressure-amplitude distribution and propagation velocity. Also, the strength of mode excitation depends on source depth. Experimental tests of the theory were conducted in a shallow-water area of the ocean. Individual modes were resolved by projecting short pulses and listening at long ranges such that the differing group velocities of propagation among modes temporally separated modal arrivals. Modal fields were sampled from near the surface to near the bottom as the depth of the source was changed incrementally. Data were obtained at frequencies of 400 and 750 Hz and for prevailing sound speed profiles in the water layer having positive, negative, and near zero gradients. Results were compared with wave theory calculations applied to an idealized model of the area. Pressure-amplitude distributions of the modal fields for the first- and second-order modes agreed well with calculated distributions. The dependence of modal field strength on source depth also was examined experimentally. In these measurements, a spatial filtering technique was used to enhance the resolution of modal fields. The predicted dependence of field strength on source depth was confirmed for the first-, second-, and in one case the third-order modes. Higher-order modes, possibly being more highly attenuated, were not observed.
Wedge Design for National Bureau of Standards Anechoic Chamber
Authors: Koidan Walter , Hruska Gale R. , Pickett Marshall A.
Published: October 2005

Design techniques for anechoic room wedges must always be used with caution because of the possibility that a manufacturer may change the properties of the material. This paper describes efforts at the National Bureau of Standards to adapt to relatively new glass wool manufactured in the United States. A “hybrid” wedge designed for a large anechoic chamber at NBS consists of glass wool of two densities: 3 lb/ft3 for the 55-in.-long tapered portion and 1.1 lb/ft3 for the 11-in.-long base. Experimental evidence indicates that the light-weight material and the 4-in air space behind the wedge, in conjunction with the heavier material, serve to produce a useful resonance absorption. The “cutoff frequency” attained for the 70-in.-long structure was about 45 Hz as measured in a 31-ft plane-wave tube. Normal acoustic impedance measurements looking into the wedge from the tip were made for the hydrid wedge and a half-scale model.
Changes in TTS Associated with Humming and Nonvocal Activities
Authors: Benguerel André-Pierre , McBay Heather D.
Published: October 2005

This investigation studies the effect of humming and of certain nonvocal activities on TTS (temporary threshold shifts) from a 5-min 500-Hz 118-dB SPL exposure. The experimental technique consisted of measuring hearing thresholds at 700 Hz before and after exposure, this exposure being accompanied by the performance of a specific activity such as humming. Analysis of the results indicates that TTS from the exposure accompanied by humming was significantly less than TTS from exposure without any supplementary activity. The following conditions were tested: (1) humming at 125 Hz (males) or 250 Hz (females); (2) humming loudly at the same frequencies; (3) humming at 250 Hz (males) or 500 Hz (females). TTS in cases (2) and (3) was consistently less than TTS in case (1). Repeatedly turning the head during exposure, an activity believed to elicit middle-ear muscle contraction, resulted in less TTS than no activity during exposure. Listening to recorded humming during exposure did not significantly alter TTS from the exposure, nor did the activity of exhaling after preparing to hum. Attenuation provided by middle-ear muscle contraction during phonation does not appear sufficient to decrease TTS to the extent that humming does. Sound may be attenuated by inefficient stapes vibration during phonation and TTS may thus be reduced. Two other possibilities are discussed that could account for the TTS decrease: interference between humming and the exposure tone; and interference (by humming) with the central control of middle-ear muscle activity.
Temporary Threshold Shifts in Chinchilla: Electrophysiological Correlates
Authors: Benitez Luis D. , Eldredge Donald H. , Templer Jerry W.
Published: October 2005

Carder and Miller [Trans. Amer. Acad. Ophthalmol. Otolaryngol. 75, 1346–1354 (1972)] exposed chinchillas for seven days to an octave band of noise centered at 500 Hz and at 95 dB SPL to produce temporary shifts of behavioral auditory thresholds (TTS) of about 48 dB which required four to seven days to recover to normal. In the present study physiological potentials were measured about 5, 24, and 48 h after exposures to the same noise for two or three days. Cochlear microphonic (CM) responses and dc endocochlear potentials were measured in each of the three cochlear turns. Input-output functions for whole-nerve action potential (AP) responses to clicks and visual detection levels (VDL) for early averaged evoked responses (AER) arising in the brain stem were also measured. Endocochlear potentials were unchanged. Shifts of sensitivity for CM in the second and third turns showed the closest numerical correspondence to behavioral TTS. Loss of sensitivity for AP was greater. Changes in VDL for the AER were consistent with behavioral TTS. This pattern of physiological changes was consistent with a disorder in the mechano-electric modulation by the hair cells plus failure to synchronize primary neural responses. Just-detectable loss of outer hair cells was also observed anatomically.
Memory for Auditory Waveform
Authors: Pollack Irwin
Published: October 2005

An attempt is made to define some limiting conditions for an auditory short-term memory relatively uncontaminated by verbal encoding or by identification of specific signals. In a one-interval test, randomly selected, interval-coded pulse patterns were either repeated exactly after an occurrence of a temporal gap, or were followed by independent randomly selected patterns. Accuracy of identification of repeated patterns is crucially dependent upon the duration of the temporal gap, upon the duration of the auditory pattern, and upon the number of successive representations of the patterns. The optimal temporal gap—about 0.5 sec—is relatively independent of the average interpulse interval, as is the optimal pattern duration—about 64 msec or 8 interpulse intervals.
An Earphone Coupling System for Acute Physiological Studies
Authors: Barnebey Alan , Nagel David C. , Carterette Edward C.
Published: October 2005

A relatively inexpensive method is described for coupling a very good electrostatic earphone to the hollow ear bar of a sterotaxic device. The electroacoustical coupling system is intended for use with mammals in acute physiological work. The amplitude and phase responses of the system, its harmonic distortion, and its response to transient stimuli are presented.
On the Derivative Relationship between Stapes Movement and Cochlear Microphonic
Authors: Dallos Peter , Durrant John D.
Published: October 2005

It is demonstrated that the cochlear microphonic (CM response recorded from both first and third turns of the guinea pig's cochlea) is a square wave in time in response to triangular motion of the malleus. The results support the hypothesis that CM is proportional to stapes velocity.
Comparability of Two Commercially Available Artificial Mastoids
Authors: Wilber Laura Ann
Published: October 2005

The new ANSI Standard S3.13-1972 for an artificial headbone lists in its appendix suggested threshold values for audiometric bone conduction calibration using a Beltone artificial mastoid. Two sets of comparisons were recently made between the Beltone 5A and the Brüel & Kjær 4930 artificial mastoids. The average values of these comparisons are given to provide numbers which may be related to those in the ANSI appendix when using a Brüel & Kjær artificial mastoid.
A 50-dB Increase in Sustained Ambient Noise from Fish (Cynoscion xanthulus)
Authors: Fish James F. , Cummings William C.
Published: October 2005

Ambient noise was measured once a month in the Salton Sea, California, from January to August 1970 with a calibrated recording system. The nighttime spectrum level at 1000 Hz increased nearly 50 dB from January to May. The change in level resulted entirely from a chorus of sounds produced by a single species of fish—the orangemouth corvina, Cynoscion xanthulus. The seasonal peak of sound production coincided with their breeding season. This increase in ambient noise level is the greatest sustained effect ever reported from underwater natural causes.
Direct Correlation of Noise and Flow of a Jet
Authors: Lee Hie K. , Ribner H. S.
Published: October 2005

A direct correlation between the flow and noise of a jet—between the “cause” and the “effect”—has been measured. Two kinds of correlations were explored, namely (1) the broad-band turbulence signal (hot-film) with the broad-band acoustic signal (microphone), and (2) the narrow-band filtered turbulence signal with the narrow-band filtered acoustic signal; the latter approach was ultimately adopted. The correlations were analyzed in terms of an extension of Proudman's form of Lighthill's integral for aerodynamic noise; this yielded the relative intensity and spectrum of the noise originating from unit volume of a jet (35 locations) and received at a farfield point (r = 96D, φ = 40°); this in turn led to the relative emission of successive “slices” of a jet versus axial distance X over the measurement range (1D ⩽ × ⩽ 7D). Qualitative agreement was found with Ribner's X° law, and the spectral peaks for each slice were located in frequency essentially as predicted by Powell. The maximum normalized broad-band correlation of 1%–2% implies roughly that a turbulence “eddy” centered at the hot-film contributes only 1%–2% of the rms sound pressure at the microphone. The total effective number of uncorrelated noise-producing eddies is thus of order (1/0.02)2, or some 2500 on an equal strength basis.
Hypersound Speeds in Sulfur Hexafluoride
Authors: Hammond C. M. , Wiggins T. A.
Published: October 2005

Sound speeds were measured from 2 to 32 amagats in sulfur hexafluoride at 26°C by spontaneous Brillouin scattering. The observed dispersion can be accounted for entirely by the nonideality of the gas. It is concluded that vibrational contributions to the specific heat are completely relaxed. No evidence of rotational relaxation was observed. Comparison of these data by commonly used techniques with those determined from ultrasonic measurements is shown to be inadequate in the case of sulfur hexafluoride for the densities used. Comparison can be made using the exact thermodynamic equation and assuming relaxing specific heat. The difference between the smoothed experimental results and the exact calculated values is less than 0.7% over the density range studied.
Vibrational Relaxation Times of Oxygen at High Pressure
Authors: Parker J. G. , Ritke D. N.
Published: October 2005

Previous values of the vibrational relaxation time of pure oxygen determined from acoustic absorption measurements in the pressure range 14–35 atm showed the pressure dependence to be other than that expected from binary collisions alone. Over this pressure range, values of the inverse relaxation time could be represented as the sum of a linear and quadratic pressure term. This paper describes results obtained by extending the pressure range to 55 atm. It is found that the data cannot be interpreted solely on this basis. A study of the effect of imposing a strong magnetic field at the highest pressure showed no effect.
Proposed Measurement of the Acoustoelectric Effect by Electron-Photon-Phonon Interaction for Hypersonic Phonons in Semiconductors
Authors: Ribakovs G. , Gundjian A.
Published: October 2005

It is proposed that amplification of phonons of frequencies in the order of hundreds of gigahertz can be investigated by measuring expected changes in the free carrier absorption coefficient which will occur from changes in the density of thermal phonons. It is shown that for photon energies greater than the thermal energy, there is a one-to-one correspondence between the energy of the incident photons and the momentum of the phonons that are required for free carrier absorption by means of intraband electron transitions. An important result derived is that the phonon energy per unit bandwidth, at a particular phonon frequency proportional to the incident radiation energy, is directly related to the ratio of the free carrier absorption coefficients during and before acoustoelectric amplification. As a specific example, the case of CO2 laser radiation absorption in n-type Ge is considered, leading to the result that at 10 K the free carrier absorption coefficient will increase by several orders of magnitude over its thermal equilibrium value during acoustoelectric amplification. In addition, the dependence of the free carrier absorption coefficient on the phonon density suggests applications in some laser devices such as photon drag detectors and amplitude modulators.
Applications of Matched Asymptotic Expansion Methods to Acoustics. II. The Open-Ended Duct
Authors: Lesser M. B. , Lewis J. A.
Published: October 2005

The method of matched asymptotic expansions is used to obtain an asymptotic solution to the Helmholtz equation for the problem of an open-ended duct. The small expansion parameter ε is given by the ratio of the duct opening H to the duct characteristic length scale L. Three separate asymptotic expansions are needed to describe the solution, one valid in the duct interior, one valid at the duct edge, and one valid in the free-space exterior region. Asymptotic matching shows that the asymptotic series must contain terms such as ε logε. Finally, results are cast in the form of a duct terminal impedance and compared with an exact solution for a parallel-sided duct.
Bubble Growth by Diffusion in an 11-kHz Sound Field
Authors: Eller Anthony I.
Published: October 2005

Bubble growth by rectified diffusion of gas was measured for single bubbles in an 11-kHz underwater sound field. Observed results are compared to calculated results for assumed isothermal or adiabatic pulsations of the bubbles. The calculated threshold for growth is consistent with observations, but the calculated times of growth exceed the observed times by factors of about 10–100.
A Corrugated Cylinder as a Waveguide and End-Fire Radiator for Underwater Acoustics
Authors: Horton C. W. , Jones J. D.
Published: October 2005

A corrugated, acoustic waveguide has been constructed to operate in a water medium over the frequency range 17.5–20 kHz. The waveguide is made of stainless-steel disks 0.0135 in. (0.343 mm) in thickness and 1.5 in. (3.81 cm) in radius separated by stainless-steel spacers 0.10 in. (2.54 mm) in thickness and 0.5 in. (1.27 cm) in radius. The phase velocity of the guide was measured experimentally and computed theoretically. After a small (5%) empirical increase was made in the value of the bulk modulus of the disks and the entrapped water, excellent agreement between theory and experiment was obtained. The waveguide was next used as the slow velocity element in an end-fire radiator. As the length of the guide increased from 10 in. (25.4 cm) to 28 in. (71.1 cm) the half-power beamwidth at 18.0 kHz of the major lobe decreased monotonically from 29° to 16°, and the height of the first minor lobe remained nearly constant at −10 dB. The shape of the radiation pattern can be predicted accurately from probe measurements near the guide plus an empirical adjustment for the contribution of the source.
The Acoustical Properties of Water-Saturated Fibrous Metal
Authors: Lastinger J. L.
Published: October 2005

Sound speed in, and sound absorption by, water-saturated stainless-steel Feltmetal were measured for eight samples of the material varying in fiber size and porosity. Measured sound absorption is in qualitative agreement with Urick's theory of sound absorption by suspensions. For those Feltmetal samples with impedance similar to that of wood, the absorption values are comparable to those previously measured for water-saturated wood. Change in absorption with increasing pressure up to 34.5 MPa (5000 lb/in.2) was negligible.
Postmasking Recovery of Human Click Action Potentials and Click Loudness
Authors: Coats Alfred C. , Dickey J. Ray
Published: October 2005

We compared postmasking recovery of click action potentials (APs) with that of click loudness in seven otologically normal subjects. The APs were recorded by averaging the pickup of a nonsurgically placed, external-meatus electrode. We found that increasing masking duration slowed recovery of both click loudness and click AP amplitude. However, the rate of recovery of click loudness was much faster than the rate of recovery of click AP amplitude. There were order of magnitude differences between the effects of click attenuation and of masking on click microphonic and AP latency. It is therefore very unlikely that middle-ear muscle contractions influenced the results. The relatively slow postmasking AP recovery (complete recovery requiring up to 500 msec) and the masking-duration effect probably originate in the sensory end-organ. These effects can therefore be regarded as manifestations of “sensory adaptation.” However, the comparatively rapid postmasking recovery of click loudness suggests that some form of (central?) compensation prevents subjective appreciation of auditory adaptation.
Latency of Whole-Nerve Action Potentials: Influence of Hair-Cell Normalcy
Authors: Wang Chang-Yang , Dallos Peter
Published: October 2005

An experimental hypothesis was derived based on the findings of the clinical simultaneous binaural median plane lateralization test and the literature review of the latency of action potentials (AP). It states that the latency of action potentials as a function of absolute signal intensity (SPL) in cochleae with different degrees of hair-cell losses is identical to that in normal cochleae at suprathreshold levels for signals with a given spectral content and a fixed rise time. The pathological cochleae were created by injections of kanamycin in guinea pigs and were monitored histopathologically, utilizing the surface preparation technique. The results show that the latency of AP as a function of SPL remains constant regardless of the pattern and degree of hair-cell loss in the cochlea, and they consequently prove that the hypothesis of this experiment cannot be rejected. For a signal with a given frequency and a fixed rise time, the latency of the onset AP apparently depends only on the magnitude of the displacement of the basilar membrane regardless of the overall magnitudes of CM or AP.
Perceptual Structure of 22 Prevocalic English Consonants
Authors: Singh Sadanand , Woods David R. , Becker Gordon M.
Published: October 2005

The similarities of 22 English consonants were judged by three different methods: (1) equal-appearing interval scale (SF), (2) magnitude estimation (ME), and (3) triadic judgments (ABX). These judgments were analyzed mainly by multidimensional (MD-SCAL and IND-SCAL), and multiple regression analysis techniques. In the city-block MD-SCAL space the SF and ME data were “best” analyzed in three dimensions and ABX data in four dimensions. In the Euclidean space the SF and ME data were analyzed in five dimensions and ABX in four. The best MD-SCAL dimensional spaces were used to test how well the spaces were predicted by the four different feature systems, namely, (1) Miller-Nicely (MN), (2) Singh-Black (SB), (3) Wickelgren (W), and (4) Chomsky-Halle (CH). The CH feature system in Euclidean space was the “best” on the criteria of consistency (Freedman's m-ranking statistics) and prediction (tau correlation). The three data sets were also analyzed in a five-dimensional IND-SCAL space with the following feature interpretations: dimension 1—sibilant, dimension 2—place (front/back), dimension 3—voicing, dimension 4—plosive, and dimension 5—nasality. The feature system composed of the above features (IND-SCAL system) was considered “best.” The features in CH system in order of perceptual importance were: (1) high; (2) voicing; (3) anterior; (4) vocalic; (5.5) nasality and strident; (7) continuant; (8) coronal; (9) low; (10) consonantal; and (11) back. The features in IND-SCAL system in order of perceptual importance were: (1) place (front/back); (2) nasality; (3) sibilant; (4) voicing; (5) plosive. Implication of the findings of this study for phonetic theory is discussed.
Cochlear Potential Response at the Round-Window Membrane of the Cat—A Reply to the Comment of G. R. Price [G. R. Price, J. Acoust. Soc. Amer. 51, 2059–2061 (1972)]
Authors: Weiss T. F. , Peake W. T.
Published: October 2005

G. R. Price [J. Acoust. Soc. Amer. 51, 2059–2061 (1972)] has stated that “the approximately constant relationship of cochlear microphonic output to stapes velocity noted by Weiss, Peake, and Sohmer [J. Acoust. Soc. Amer. 50, 602–615 (1971)] is probably a function of a bias introduced by the choice of electrode location, i.e., the bone near the round window.” He also argues that “the most appropriate recording site would seem to be [on] the round window.” We have measured cochlear potential responses to tones as a function of frequency with wire electrodes simultaneously on the round-window membrane (ERW) and on the ventral surface of the petrous bone near the round window (EG). The ratio of the magnitude of these potentials, |ERW/EG|, is constant (within ±2 dB) for frequencies between 400 and 20 000 Hz and depends upon frequency below 400 Hz. These results, together with those of Weiss et al., lead to the conclusion that |ERW/ẊS| is approximately constant between 400 and 10 000 Hz, where ẊS is the stapes velocity. Comparison of our measurements of ERW, with those of Price [J. Acoust. Soc. Amer. 49, 1899–1901 (1971)] reveals that the greatest differences lie in the range of frequencies between 5 and 20 kHz. The magnitude of the difference increases with frequency and is approximately 20 dB at 20 kHz. Analysis of the methods used to measure sound pressure at the tympanic membrane in these two studies indicates that the differences might result in large part from inaccuracies Price's measurements of sound pressure.
Effect of transverse shear deformation on vibrations of planar structures composed of beam-type elements
Authors: Dong Stanley B. , Wolf Joseph A.
Published: October 2005

A finite element beam-type model considering transverse shear deformation is presented which utilizes Timoshenko's original kinematic variables. A direct calculation of the distribution of energies due to extension, flexure, and shear is indicated. For beam vibrations, comparison of the present results with other analyses shows that the current formulation is extremely effective for cross sections whose depth is comparable to a wavelength. Natural frequencies of frames and arches are computed using the present element and are compared with values based upon neglect of transverse shear deformation to illustrate this effect quantitatively.
The influence of human factors on the performance of a real-time speech recognition system
Authors: Carpenter B. E. , Lavington S. H.
Published: October 2005

The performance of real-time speech recognition systems is observed to depend upon the environments in which they are used. Human factors, caused for example by operator frustration, significantly affect success rates. A set of experiments with a word recognition system is described which quantifies this change, whilst the system is being used to control the movement of a displayed cross on a screen.
Acoustically augmented diffusional transport
Authors: Fogler Scott , Lund Kasper
Published: October 2005

The present work considers enhancement of mass transport resulting from superimposing an ultrasonically induced convective transport on a diffusional transport. As a result of the nonlinearities in the Navier-Stokes equation, a time-dependent secondary flow called acoustic streaming can be produced when an acoustic wave is passed through a medium. Between adjacent vortices or cells, molecular diffusion is the only means of transport; however, within each cell, mass transport is primarily by convection. Increases in the rate of mass transfer of the order of 150% above the normal diffusional flux were found. The theoretical analysis and results presented have application to systems in which ultrasonics may be used to increase mass transfer through membranes (e.g., dialysis), and to increase the efficiency of very active catalytic systems and of solid-liquid extraction systems.
Multiple scattering of sound by a periodic line of obstacles
Authors: Twersky Victor
Published: October 2005

Equations derived earlier for multiple scattering by arbitrary three-dimensional configurations are applied to a line of equally spaced identical obstacles. We develop several different representations and approximations for the field and derive the appropriate energy and scattering theorems. Spherically symmetric scatterers are considered as a special case. In general, the results are analogous to those obtained before for the two-dimensional problem of scattering by a planar grating of identical cylinders but differ essentially in that now the scattered modes are conical instead of planar. A major difference is that resonance maxima (analogous to the Wood's anomalies for the planar grating) may occur not only for wavelengths that are slightly larger than the grazing (Rayleigh) wavelengths, but also for wavelengths that are slightly smaller. We also derive closed-form approximations for small scatterers with arbitrary spacing, and then specialize the results to small spacing.