bluuebunny/crossref_metadata_2025 huggingface dataset:
Capacitance microphone dynamic membrane deflections
Authors: Warren J. E. , Brzezinski A. M. , Hamilton J. F.
Published: October 2005

In order to accurately describe the operation of capacitance microphones, it is necessary to have solutions for both the static and dynamic deflections of the moving electrode. The present paper describes an application of finite difference methods to the differential equations describing the dynamic membrane motion due to the acoustic excitation. The authors have previously presented numerical solution approaches to the static deflections caused by the electrical biasing of the microphone [J. Acoust. Soc. Am. 52, 711–719 (1972)]. The dynamic solution approaches presented here include the effects of the static deflections and the motion of the thin air film between the microphone's electrodes. The numerical results are compared with published results for simplified stationary electrode geometries and with experimental data on more complicated geometries at different tension levels. The predicted mode shapes change greatly, depending upon the magnitudes of the membrane tension and microphone's back chamber volume. Owing to the accuracy of these methods, they have applications in microphone optimization and characterization of the time dependent properties of electret microphones.
Consonant confusions in noise: a study of perceptual features
Authors: Wang Marilyn D. , Bilger Robert C.
Published: October 2005

Consonant confusion matrices were obtained for four sets of CV and VC nonsense syllables presented both in quiet and in the presence of a masking noise. A sequential method of partitioning transmitted information for confusion matrices was developed and used to test the hypothesis that when the internal redundancy of feature systems is taken into account, certain articulatory and phonological features of consonants consistently account for transmitted information better than other, closely related, features. Results of the analyses indicate that for most confusion matrices several feature systems can be shown to account equally well for transmitted information, and that across syllable sets and listening conditions, there is little consistency in the identification of perceptually important features. The implication of these findings with respect to the existence of natural perceptual features for consonants is discussed.
Vibrational relaxation for UF6, WF6, MoF6, and SF6
Authors: Doi Hideo , Kono Yutaka , Higashi Kunio
Published: October 2005

The acoustic dispersion and absorption were analyzed for four hexafluoride molecules (UF6, WF6, MoF6, and SF6) by using the first approximation of the distorted wave method. From the result of calculation, double dispersion is expected for UF6, and is not expected for WF6, MoF6 and SF6. It is also expected that the temperature dependence of vibrational relaxation times of the four molecules will satisfy the T−1/3 law. The computed results are compared with the available experimental data for SF6 and WF6.
Proof that the piezoelectrically stiffened velocity is at least as great as its corresponding unstiffened value
Authors: Epstein Seymour
Published: October 2005

When the piezoelectric stiffening contribution is not large compared to the unstiffened purely elastic contribution, the characteristic equation yields perturbation-type solutions. This implies that the stiffened mode corresponds to an unstiffened one. The solutions show that the stiffened velocities are at least greater than the corresponding unstiffened ones for piezoelectric contributions which, for propagating nonattenuating waves, are always positive or zero. The stiffening contribution term may be used to calculate conditions for which unstiffened modes exist in piezoelectric crystals.
Reflection and transmission of waves by a fiber-reinforced material
Authors: Bedford A. , Sutherland H. J.
Published: October 2005

A two-continuum theory is used to analyze the reflection and transmission of waves by a plane interface between homogeneous and fiber-reinforced elastic materials. The solutions are compared to experimental data obtained through ultrasonic measurements of waves transmitted through water into an aluminum plate containing tungsten fibers. Comparisons are presented of dispersion and attenuation in the fiber-reinforced material as well as reflected and transmitted wave amplitude ratios.
Effect of hydrodynamic variations on sound transmission across a geostrophic flow
Authors: Franchi E. R. , Jacobson M. J.
Published: October 2005

A previously developed environmental-acoustics model for sound speed in a geostrophic flow is used to examine refracted/bottom-reflected (RBR) ray transmissions between a bottom-mounted source and receiver, in a direction perpendicular to the current flow. It is shown that explicit current effects may be assumed to be negligible, but that implicit effects of current on sound speed are significant. Ray geometry, travel time, spreading loss, and the total acoustic field associated with RBR transmissions are examined in detail. A numerical example is presented which models propagation studies over the Miami-Bimini installation across the Florida Straits. It is found that acoustic phase and amplitude are significantly affected by variations in the current. Finally, current is related to measured transport fluctuations, and a comparison is made between theoretical and experimental phase variations. Good qualitative agreement is achieved which clearly illustrates the importance of current (transport) variations on cross-current propagation, and demonstrates that the strong experimental correlation between environmental and acoustic properties can be modeled successfully using environmental-acoustics models.
Free vibrations of rhombic plates and membranes
Authors: Bauer Louis , Reiss Edward L.
Published: October 2005

Natural frequencies and modes for the simply supported and the clamped 60° rhombic plate have been obtained numerically.
Comments on “Rytov's method and large fluctuations” [L. R. Brownlee, J. Acoust. Soc. Am. 53, 156–161 (1973]
Authors: Corrington Murlan S.
Published: October 2005

The integral for the mean value of the pressure distribution function can be evaluated in terms of standard tabulated functions.
Procedures for comparing hydrophone noise with minimum water noise
Authors: Woollett Ralph S.
Published: October 2005

In a recent paper by Henriquez, the noise level of a hydrophone is shown falling below the thermal water noise level at high frequencies. The writer believes this should not happen and presents a data-processing procedure for noise evaluations which will ensure that it will not. The use of equivalent plane waves to represent electrical noise is deprecated, and the concept of the isotropic acoustic equivalent of electrical noise is introduced and used in their stead.
Author's reply to “Procedures for comparing hydrophone noise with minimum water noise” [R. S. Woollett, J. Acoust. Soc. Am. 54, 1376 (L) (1973)]
Authors: Henriquez T. A.
Published: October 2005

Noise measurements made under normal loading conditions in water tend to bear out Dr. Woollett's observations.
Measurement of “instantaneous” carrier frequency of bat pulses
Authors: Kindlmann P. J. , Berman L. B. , Johnson R. A. , Pollak G. D. , Henson O. W. , Novick A.
Published: October 2005

A technique is presented for the precise measurement of the “instantaneous” carrier frequency of bat pulses. An augmented commercial frequency counter is used to measure the period (or a short-term period average) of the bat pulse carrier. An expanded scale readout from the frequency counter is obtained via digital-to-analog conversion, yielding a direct oscilloscope display of small carrier frequency deviations juxtaposed to the signal being analyzed. This is illustrated by bat pulses containing frequency sweeps and Doppler-shifted echoes.
Monte Carlo applications to acoustical field solutions
Authors: Haviland John Kenneth , Thanedar Balakrishna D.
Published: October 2005

The Monte Carlo technique is proposed for the determination of the acoustical pressure-time history at chosen points in a partial enclosure, the central idea of this technique being the tracing of acoustical rays. A statistical model is formulated and an algorithm for pressure is developed, the conformity of which is examined by two approaches and is shown to give the known results. The concepts that are developed are applied to the determination of the transient field due to a sound source in a homogeneous medium in a rectangular enclosure with perfect reflecting walls, and the results are compared with those presented by Mintzer based on the Laplace transform approach, as well as with a normal mode solution. In contrast with these, the Monte Carlo method is not restricted to the case of perfectly reflecting walls, since absorptive walls can be handled. Possible future developments are indicated which would, it is believed, make the Monte Carlo method a valuable tool when boundary conditions are complex or when the medium is inhomogeneous.
Dilational-mode sound transmission in sandwich panels
Authors: Smolenski C. P. , Krokosky E. M.
Published: October 2005

Dilational vibration modes have been shown to produce an undesirable “coincidence type” response in the sound-transmission spectrum of lightweight-core sandwich panels in the medium to high-frequency range. In particular, it was found that the dilatational coincidence region often occurs at considerably lower frequencies than those coincidence effects produced by flexural vibration. The governing characteristic frequency equations were developed by employing the Rayleigh-Ritz Energy Principle for a sandwich panel with variable dimensions and properties. The present solution also employs a general strain energy relation without restricting the skin materials to be identical. Eight characteristic natural frequencies representing dilatational, flexural, and longitudinal vibration were determined for the fundamental as well as higher order modes as a function of panel dimensions and material properties. Throughout this study particular attention was given to the influence of core properties on the dilatational natural frequencies. Experimental panels with various face and core materials were tested under random incidence sound-transmission conditions and found to compare favorably with the theoretical predictions.
Theory of binaural interaction based on auditory-nerve data. I. General strategy and preliminary results on interaural discrimination
Authors: Colburn H. Steven
Published: October 2005

We discuss initial research on a model of binaural hearing in which the peripheral transduction from acoustical waveforms to firing patterns on the auditory nerves is explicitly described. In most of this initial research, attention is focused on interaural time discrimination, and the processing that follows the peripheral transduction (the central processing) is assumed to be ideal. By imposing limitations on the central processing and computing the consequences for performance, we find that performance at least as good as experimentally observed performance can be achieved with central processing that is substantially restricted.
Critical masking interval: a temporal analog of the critical band
Authors: Penner M. J. , Cudahy Edward
Published: October 2005

The critical masking interval, the time period during which noise is effective in masking a brief click, was measured in two independent experiments. The first paradigm was the temporal analog of Fletcher's critical band experiment. That is, the click was presented in the temporal center of the noise, and its threshold was measured as the masker duration was varied. The second paradigm investigated the temporal analog of Greenwood's [J. Acoust. Soc. Am. 33, 484–502 (1961a)] masking experiment; that is, a click was moved temporally through the noise burst. The two paradigms yielded similar numerical estimates of the critical masking interval. Further, the critical masking interval was not greatly affected by the stimulus' bandwidth.
Noise propagation in cellular urban and industrial spaces
Authors: Davies Huw G. , Lyon Richard H.
Published: October 2005

The effect of multiple barriers on the propagation of noise in urban and industrial environments is described by a cell model. The cell boundaries are formed by walls, machinery, etc., and each cell contains noise sources. The noise field both within and outside the souce region is discussed. A comparison with the results of previous investigations shows that the cell model correctly predicts the residual background level in traffic-free zones in urban areas.
Theoretical prediction of sound attenuation in acoustically lined annular ducts in the presence of uniform flow and shear flow
Authors: Ko Sung-Hwan
Published: October 2005

An investigation is made of the sound attenuation in a lined annular duct with flow. The eigenvalue equation in the presence of uniform flow is derived by matching the radial component of the particle displacement and acoustic pressure across a vortex sheet located an infinitely small distance from the facing sheet of an acoustic lining. The eigenvalue equation in the presence of shear flow is developed by matching the acoustic pressure and the radial component of the particle displacement at the interface between the regions of uniform flow and shear flow. Theoretical prediction of the sound-attenuation spectrum is based on an acoustic-energy flow in which the effect of the mean flow is taken into account. The results presented in this paper are limited to those which are typical for the geometry of an annular duct. Effects of mean flow Mach number, boundary-layer refraction, and acoustic impedance on the sound attenuation for a given duct configuration are found to be similar to those in rectangular- and circular-duct problems.
Glottal-area time function and subglottal-pressure variation
Authors: Koike Yasuo , Hirano Minoru
Published: October 2005

High-speed photography of the vibrating laryngeal structures was done on one female subject simultaneously with a direct recording of the vibratory air-pressure variation in the trachea. The glottal dimensions and pressure data were obtained from this film using a semiautomated digital-reduction technique. It was observed that the peaks of the subglottal-pressure waves correspond with the dips in the glottal-area waves, and also that the fundamental periodicity of the subglottal-pressure wave represents the glottal-area periodicity with good accuracy. Relations between the glottal-area function and the glottal-width function were considered. It is suggested that the glottal-width function may be considered to be an approximate estimate of the glottal-area function if the vibrating structure in the larynx is unaffected by pathology.
Vibrational relaxation in multiple mixtures of two-state gases
Authors: Dean E. A.
Published: October 2005

The elements of a symmetrical matrix for the eigenvalue problem for vibrational relaxation times in a mixture of n two-state gases are given. These elements depend upon the reaction rates for the various transitions and upon the mole fractions of the gases. Calculations for the three-gas mixture O2/H2O/D2O are compared with experimental results for these mixtures. The large effect of a 50% D2O/H2O impurity on the relaxation time of O2 is attributed to a three-step energy-exchange chain: the near-resonant V V transfer of vibrational energy from O2 to H2O, then a rapid exchange of vibration between H2O and D2O, followed by the de-excitation of D2O by O2, which is an order of magnitude faster than the de-excitation of H2O by O2.
Ultrasonic absorption measurements in oriented benzene crystals
Authors: Victor A. E. , Beyer R. T.
Published: October 2005

The ultrasonic absorption coefficient has been measured in single benzene crystals along the principal crystallographic axis. The range 6–38 MHz and at temperatures between 170° and 250°K. All three cases indicated a relaxation frequency near the middle of the frequency range (different in each case), and the values along the a- and c-axes suggest the presence of other relaxation frequencies. The measurements have been compared in detail with the theories of Liebermann and Danielmeyer, but the agreement is far from satisfactory.
Acoustic propagation in ducts with varying cross sections
Authors: Nayfeh Ali Hasan , Telionis Demetri P.
Published: October 2005

The method of multiple scales is used to derive the equations that describe the spatial and temporal variation of the amplitudes and phases of a wave packet propagating in slowly varying hard-walled or lined ducts. The analysis is carried out for rectangular as well as circular ducts. These equations are statements of the conservation of energy. For large admittance or high-frequency modes, an approximate expression is obtained for the attenuation. This expression shows that all possible acoustic modes are attenuating. The results also show that decreasing the cross-sectional area can lead to elimination of some of the acoustic modes.
Acoustic radiation from a spherical source embedded eccentrically within a fluid sphere
Authors: Thompson William
Published: October 2005

The radiation from a spherical source vibrating with an arbitrary, axisymmetric, time-harmonic velocity distribution while positioned at an arbitrary point within a fluid sphere, which is embedded in another infinite fluid medium, is computed. This configuration is an idealization of a spherical acoustic lens, with focal point inside the lens, when used as a sound projector. The translational addition theorem for spherical wave functions is used to express series of wave modes centered at one sphere in terms of modes centered at the other, thereby facilitating the task of satisfying the boundary conditions. The radiation load on the source and the farfield directivity pattern are evaluated for representative values of the many parameters that characterize the problem, such as the wavelength size of the lens and source, the relative characteristic impedances and sound velocities of the two fluid media, the position of the source, and the velocity distribution on the source sphere. In general, no great increase in the radiation resistance is noted when the source is at the focal point of the lens. The focal points for monopole and dipole sources are usually not coincident. The size of the source has little effect upon the farfield directivity pattern.
Parameterless examples of wave propagation
Authors: Wood D. H.
Published: October 2005

Our results are always parameterless, that is, explicit functions of the problem variables found without using rays, ray equations, or ray parameters. When c = sinhz, we find a series solution of the reduced wave equation ▿2u + ω2c−2u = 0 characterizing radiation from a point source at (x0, y0, z0) in three dimensions. Ignoring the shadow region (x − x0)2 + (y − y0)2 > π2, we use formal methods to find the first three terms of a series for the radiation solution, beginning with the term exp[iτ(ω2 − 1/4)1/2]{sinρ/[ρc(z)c(z0)]}1/2 cschτ, τ defined by cosh τ = (coshz coshz0 − cosρ)/(sinhz sinhz0) and ρ = [(x − x0)2 + (y − y0)2]1/2. In all of two-dimensional (x, z) space except the shadow region |x − x0| > π, formal methods and reexamination of Cohn's Riemann functions show that Qλ(coshτ) is an excellent approximation to the radiation solution. Here Qλ is a Legendre function, λ = 1/2 + i(ω2 − 1/4)1/2, and ρ = x − x0. Special and limiting cases of the above give analogous results for c equal to coshz, cosz, ez, z, and 1. We obtain Pekeris' exact solutions when c(z) = z, and the classical solutions when c(z) = 1.
A rapid method for studying acoustic behaviour
Authors: Nute M. E. , Slater K.
Published: October 2005

A new swept-frequency technique for studying acoustic behaviour is presented and has certain advantages over established methods where a rapid inexpensive assessment of the approximate acoustic performance of a material in the laboratory or in a field situation is required. The general behaviour may be envisaged by inspection, or a detailed analysis of the performance in selected frequency bands may be carried out by simple measurement and calculation in a few minutes.
Susceptibility to damage from impulse noise: chinchilla versus man or monkey
Authors: Luz George A. , Lipscomb David M.
Published: October 2005

Behavioral audiograms were taken on five surgically monaural chinchillas at 0.75, 1.5, 4.0, 6.0, 7.9, 11.0, 14.5, and 16.5 kHz. After exposure to 1 to 4 impulses of 168-dB peak SPL and 60-μsec A-wave duration, temporary threshold shift was monitored at 1.5, 6.0, and 14.5 kHz for 32 days and complete audiograms taken at 64 days post-exposure. Shifts were similar to those found by other researchers who have exposed the chinchilla to similar impulses, but were larger than those seen in monkeys and men exposed to the same impulse noise source. Cochlear hair cell losses for the five subjects exposed to one to four impulses were small and not significantly different from those of five others exposed to 10 to 40 impulses (but not tested behaviorally). The conclusions paralleled those of Hunter-Duvar and Elliott [J. Acoust. Soc. Am. 52, 1181–1192 (1972)] in that stimulation “sufficient to produce permanent threshold shifts of 10–20 dB may not produce anatomical injuries to the organ of Corti that are detectable by phase microscopy.” Caution was urged in generalizing the results of impulse noise studies in chinchilla to human damage risk criteria. The use of pre-exposure impedance measures to rull out middle ear conductive losses was also suggested for future studies.
Mathematical model for volume reverberation: experiment and simulation
Authors: Jobst William J. , Šmits Tālivaldis I.
Published: October 2005

An experiment performed in deep water near San Clemente Island, California, showed that discrete scatterers were the primary source of acoustic volume reverberation at the test site. Scatterers reflected the incident waveform without apparent distortion. Estimates of the scatterer density and scatterer reflectivity distribution were obtained from experimental data, but the estimates were distorted by the transducer beam pattern and by overlapping echoes. Analysis of the reverberation envelope showed that reverberation was homogeneous in the horizontal plane and that the reverberation envelope amplitude was not Rayleigh distributed. A computer was programmed to simulate volume reverberation according to a discrete scattering model developed by Faure, Ol'shevskii, and Middleton. The scatterer density and reflectivity estimated from experimental data were changed until simulated and measured reverberation envelopes were statistically alike. When simulated and measured envelopes were alike, improved estimates of scatterer density and scatterer reflectivity were obtained from the simulation. The scatterer density which gave best agreement between simulated and measured envelopes was 0.0010 scatterers per cubic foot. The scatterer reflectivity was approximately exponentially distributed.
Farfield radiation of internally generated transient acoustic pulses transmitted through a spherical shell
Authors: Menton Robert T. , Magrab Edward B.
Published: October 2005

The effects of a fluid-loaded spherical shell on the propagation to the farfield of an internally generated, transient acoustic pulse is obtained. The pulse is generated by a spherical transducer that is located concentrically within the shell and has a specified spatial and temporal velocity distribution. A shell theory that incorporates the effects of transverse shear and rotary inertia is used. The fluid between the transducer and the shell, and the fluid external to the shell, is described by the linear acoustic wave equation. The spatial dependence of the transmitted pulse is expanded in a series of spherical harmonics. The temporal dependence is determined by numerical inversion of the Fourier transformed solution. Computations are performed for axisymmetric transducer velocity pulses of realistically short duration. It is found that a steady-state analysis is incapable of predicting the nature of the farfield pulse, since the applied waveform and the farfield waveform were dissimilar. The shell membrane breathing mode, shifted up in frequency from its in vacuo value because of the stiffness of the confined volume of fluid between the transducer and the shell, is found to dominate the farfield response.
Pitch of dichotically delayed noise and its possible spectral basis
Authors: Bilsen F. A. , Goldstein J. L.
Published: October 2005

Pitch can be signalled by interaural differences in timing, but it is unknown how the intercochlear timing mediates pitch. Pitch of complex tones can be well understood in terms of a central pitch mechanism that reads across the frequencies of a centrally presented spectrum. We consider whether pitch phenomena signalled by binaural timing are also compatible with auditory processing through tonotopic organization. Known binaural pitch phenomena produced by stimuli comprising two wideband Gaussian noise sources, each with different interaural delay were examined. The major findings are that (i) a single noise source with interaural delay τ is adequate to produce a pitch corresponding to 1/τ, (ii) the medially lateralized pitch image is little affected by the addition of a second independent noise source presented in antiphase, (iii) the dichotic pitch is similar to monaural repetition pitch, for which the stimulus to the ear comprises a noise source added to its delay, and (iv) the image of dichotic repetition pitch is much more faint and compact than that of monaural repetition pitch. Durlach's [J. Acoust. Soc. Am. 34, 1096–1099 (1962)] equalization and cancellation model of binaural signal detection is adapted to describe the compatibility between the binaural pitch phenomena and auditory mediation of pitch by central spectral patterns.
Phase effects in a three-component signal
Authors: Buunen T. J. F. , Festen J. M. , Bilsen F. A. , van den Brink G.
Published: October 2005

Phase effects in a particular three-component signal, consisting of the 9th, 10th, and 11th harmonic of 200 Hz were studied. The main interest was the effect of phase changes on the prominence of the residue pitch evoked by this signal. The prominence of residue pitch appears to be correlated to the acoustical power spectrum of the signal, modified by the internally generated combination tones. An estimate of this “internal spectrum” was obtained by means of a cancellation technique. Because of an interaction of combination tones and acoustical components, this “internal spectrum” is phase-dependent. In this context de Boer's phase rule is reconsidered. The residue pitch seems to be most prominent if there are prominent lower harmonics in the “internal spectrum.” In general, subjective phase effects in this signal, which could be described as changes in timbre, seem to be dependent on changes in the “internal spectrum.”
Equal loudness pressures determined with a decaying oscillatory waveform
Authors: Victoreen John A.
Published: October 2005

Equal loudness measurements are reported for six young normal-hearing adults over a frequency range of 250 to 6000 Hz. The signals consisted of an exponentially decaying oscillatory waveform whose decay rate per cycle was constant with signal frequency. The results show a well-defined relation between sound pressure for equal loudness and signal frequency. A mathematical expression for this relation is given and calculations based on it were consistant with the averaged data over a pressure range of 0.0001 to 100 μbars. With signals of the type employed sound pressure for most comfortable loudness was found to be independent of frequency.
Analysis of the operation of electret transducers subject to large electrode displacements
Authors: Sessler G. M.
Published: October 2005

An analytical study of the operation of electret transducers subject to relative displacements of the electrodes comparable to the thickness of the air gap (or air gaps) between electret and electrodes is presented. In particular, the relations between generated voltage and time history of the transducer capacitance are derived for transducers terminated by a combination of resistive and capacitive components. Following this analysis, graphical and numerical results for the shape and peak amplitude of the voltage response due to displacements with trapezoidal time dependence are presented.
A multichannel acoustic emission monitoring system with simultaneous multiple event data analyses
Authors: Ying S. P. , Hamlin D. R. , Tanneberger D.
Published: October 2005

A multichannel acoustic emission monitoring system has been developed recently. The system possesses high sensitivity for the sound pressure level of the emission and is concerned with the frequency selection to overcome various background noise disturbances. The signal and data processing unit can process multiple acoustic emission events simultaneously for analyses. The cathode ray tube screen of a computer is used for a real time graphic display of the number of events at individual locations of the emission sources.
Sound attenuation in turbulent pipe flow
Authors: Ingard Uno , Singhal Vijay K.
Published: October 2005

Results of steady-state and pulse measurements of upstream and downstream attenuation of sound in turbulent pipe flow are presented and compared with calculated values obtained from a simple model in which the sound is treated as a quasistatic perturbation of the steady flow in the pipe.
Dispersion relationships in sediments and sea water
Authors: Horton C. W.
Published: October 2005

The Kramers-Kronig dispersion relationship is used to discuss the interdependence between velocity and attenuation in sediments and sea water. It is shown that if the attenuation is proportional to the n th power of the frequency, there is no velocity dispersion if n = 1 or 2 but that dispersion exists for nonintegral values of n. The theoretical relation agrees with the experimental measurements of L. Hampton for a sediment with n = 1.37. The relaxation process of sea water is considered and it is shown that the velocity dispersion is slightly greater than the precision of velocity measurements.
Wave propagation in elastic rods of arbitrary cross section
Authors: Rosenfeld Gerald , Keller Joseph B.
Published: October 2005

Asymptotic expansions are found for both long and short waves propagating in elastic rods of arbitrary cross section. The results are compared with the well known approximate theories for long waves and show to what extent those theories are accurate. They also yield corrections to them.
In memoriam Georg von Békésy 1899–1972
Authors: Tonndorf Juergen
Published: October 2005

This introduction to a group of papers devoted to the memory of Georg von Békésy reviews briefly the character and significance of his scientific work.
Cochlear mechanics, nonlinearities, and cochlear potentials
Authors: Dallos Peter , Cheatham Mary Ann , Ferraro John
Published: October 2005

Cochlear microphonic (CM) magnitude functions are shown from various turns of the cochlea at constant sound pressure level (SPL), constant stapes displacement, and constant stapes velocity. The similarities of these curves with basilar membrane displacement functions are considered. The influence of CM nonlinearity on the shape of the plots is discussed, and it is demonstrated that the response is extremely nonlinear in a narrow frequency range above the best frequency of the electrode location, while at other frequencies it is much more linear. All nonlinear phenomena that are demonstrable in cochlear potentials, namely harmonic distortion, summating potential generation, and interference effect, are primarily concentrated in the aforementioned nonlinear frequency region.
Within- and between-modality correlation detection
Authors: Pollack Irwin
Published: October 2005

You are given two information finite-state sources. Your task is to determine the correlation between the sources by sensory processing alone. Should you present the sources to the ears, to the eyes, or to the skin, or should you present one source to one modality and the other to another modality? Answer: within-modality comparisons can be accomplished at high presentation rates where the display can be appreciated in terms of overall properties (“perceptualization”); by contrast, between-modality comparisons can be accomplished only at slow presentation rates where individual events must be processed.
Lateralization of tonal stimuli by the cat
Authors: Wakeford Onslow S. , Robinson Donald E.
Published: October 2005

The ability of the cat to “lateralize” tonal signals having interaural intensive or interaural temporal disparities was measured. Interaural intensive differences were studied at 0.5, 1.0, and 3.0 kHz. Interaural temporal differences were studied at 0.5, 1.0, 2.0, and 3.0 kHz. Miniature audio transducers were employed to present the stimuli to the animals. The transducers were held in a fixed spatial relation to the auditory canal by means of “pinna inserts” and leather helmets. An avoidance response in a shuttle box was used as the dependent variable. The animals' task involved the detection of a right-left reversal in a gated sequence of tone bursts. The cat appears to be about as sensitive as the human to both interaural intensive and temporal disparities at each of the frequencies studied.
Rule-synthesis of speech by word concatenation: a first step
Authors: Olive Joseph P. , Nakatani Lloyd H.
Published: October 2005

Some preliminary work on rule-synthesis of speech by word concatenation is described. Words spoken in isolation were analyzed to extract their pitch, formant, duration, and amplitude parameters. The parametric representations of the words were concatenated and modified, and speech was synthesized from the modified parameters. An experiment was run to determine which parameters required modification to achieve natural prosody in the concatenated speech. The results indicated that the only parameter requiring substantial contextual modification was pitch; modifications of segment duration and formant coarticulation had minimal effects on prosody. These results were incorporated into a scheme for rule-synthesis of telephone numbers by digit concatenation. An evaluation experiment found the rule-concatenated numbers to be as comprehensible as naturally spoken numbers, and as pleasant as numbers resynthesized from naturally spoken numbers.
Investigation of the sound-producing mechanism of the jew's harp
Authors: Adkins C. J.
Published: October 2005

It is shown that the jew's harp excites the mouth cavity by producing short pulses when the lamella passes through the frame. A model is proposed for the mechanism by which the pulses are generated. When the mouth cavity is tuned to low frequencies, its natural resonance time is longer than the period between successive pulses and the harmonic series of the fundamental frequency of the lamella dominates the sound as the mouth tuning is changed. At high frequencies, the mouth cavity and ear respond to each successive pulse independently so that the dominant sensation of pitch coincides with the natural resonance frequency of the mouth and may be tuned continuously.
Comparison of methods for absolute calibration of ultrasonic fields
Authors: Breazeale M. A. , Dunn F.
Published: October 2005

Methods of determining the absolute ultrasonic pressure amplitude under identical circumstances are compared. Methods used are (1) radiation force on a small sphere, (2) thermoelectric probe, and (3) three optical techniques.
Response to “Comments on ‘Torsional vibration of an elastic solid containing a penny-shaped crack,’” [A. M. Abo-Zena, J. Acoust. Soc. Am. 54, 211–212(L) (1973)]
Authors: Sih G. C. , Loeber J. F.
Published: October 2005

The authors have been aware of the numerical inaccuracies caused by one error in their earlier analyses on the stress wave diffraction by a penny-shaped crack. The corrected results have already been published in the open literature.
Wave propagation in elastic media with a periodic array of discrete inclusions
Authors: Christensen R. M.
Published: October 2005

This study concerns the propagation of time harmonic waves in a continuous medium in which is embedded a three-dimensional periodic array of discrete inclusions. Both phases are taken to be elastic, and the symmetry characteristics of the combination are of the type of cubic crystals. A perturbation method of analysis is employed to obtain the steady-state periodic wave solution where full account is given to the multiple interacting reflections of shear and dilatational waves. When the solution is specialized to the case of constant moduli with only the density being variable, an attenuation factor for transient waves is extracted heuristically.
Wave propagation in anisotropic bars of rectangular cross section. III
Authors: Nigro Nicholas J. , O'Malley Patrick A.
Published: October 2005

The Ritz method is used to obtain the dispersion curves for the problem of torsional-wave propagation in anisotropic bars of infinite length and rectangular cross section. The first three dispersion curves are presented for orthotropic, tetragonal, hexagonal, cubic, and isotropic bars with several ratios of width to depth. The displacements corresponding to various dimensionless phase velocities are presented and discussed in some detail. The investigation is an extension of previous work [J. Acoust. Soc. Am. 40, 1501 (1966); 43, 958 (1968); 46, 639 (1969)] in elastic-wave propagation.
Ray-acoustic intensity in a moving medium. I
Authors: Thompson Robert J.
Published: October 2005

A quite general expression for ray-acoustic intensity in terms of ray trajectories in a moving medium is derived. The speed of sound and the three components of the velocity of the medium can be functions of the three space variables. They can even depend on time. The only restriction is that the speed of the medium must be subsonic. The fact that the sound source may not radiate energy uniformly in all directions is taken into account. It is shown that for the special case of a motionless medium the results reported here reduce to some known results.
A correlation technique for determining the self- and mutual-radiation impedances of transducers in an array
Authors: Rudgers Anthony J.
Published: October 2005

Linear-system analysis is applied to a transducer array and an input-output relation is established from which the self- and mutual-radiation impedances of the array transducers may be determined. The radiation impedances are determined by applying currents at the electrical terminals of the array transducers that are derived from multicorrelated time series and by measuring the crosscorrelation between these currents and the voltages appearing at the electrical terminals. Since only electrical quantities are involved, it is possible to obtain the radiation impedances of a transducer array of very general character because no knowledge of the nature of the acoustic field of the array or of the mechanical motion of its radiating surfaces is needed. So long as the transducer-array system is linear and of finite size, it may consist of transducers of dissimilar types, having arbitrary shapes and sizes, with normal velocities that are not necessarily uniform across the transducer faces. Moreover, the transducers may be located in one or more baffles of arbitrary shape and acoustic characteristics and one or more reflectors— these, too, being of arbitrary shape, size, and acoustic characteristics—may be located in the vicinity of the radiating array.
Kinetic theory of sound propagation in gaseous mixtures. I. Two-fluid 5-moment, 13-moment, and Navier-Stokes Theories
Authors: McCormack Francis J. , Craven David E.
Published: October 2005

Plane sound wave propagation in binary mixtures of monatomic gases is studied using sets of two-fluid 5-moment, 13-moment, and Navier-Stokes equations. Numerical solutions are obtained for the absorption coefficient and propagation speed as a function of the ratio of frequency to pressure. The physical parameters upon which the solutions depend are the molecular mass and number density ratios and the ratios of the force constants in the Maxwell-molecule intermolecular force law. The different roots of the dispersion relations are discussed, and the 13-moment and Navier-Stokes solutions are presented for the sound mode in He-Ar mixtures of varying relative concentration. These agree very favorably with the existing experimental data and the previous two-fluid theory of Goldman, especially the Navier-Stokes solutions. In addition, absorption curves for He-Ne and He-Xe are presented. It is found that the two-fluid 13-moment and Navier-Stokes solutions for each mixture considered behave qualitatively very much like the corresponding solutions for a simple gas, and consequently share the same successes and failures. Also, briefly discussed is a more refined model equations approach (of which the present theories can be considered the first approximation), the details of which will be presented in a later paper in this series.
Hypersound speeds in carbon disulfide, acetone, and benzene at high pressure
Authors: Smith J. H. , Peterson L. M. , Rank D. H. , Wiggins T. A.
Published: October 2005

Hypersound speeds have been measured in carbon disulfide, acetone, and benzene by means of optical mixing employing stimulated Brillouin scattered light at 27°C in the pressure range from 1 to 1000 atm. Ratios of the specific heats at constant pressure and volume were also deduced. In carbon disulfide the dispersion between hypersonic and ultrasonic frequency was essentially constant over the pressure range studied, In acetone, hypersound speeds increased linearly with increase in pressure. In benzene, complete vibrational relaxation does not take place above 400 atm. The hypersound speeds remained essentially constant at higher pressures indicating a decrease in the ratio of specific heats that is not observed at ultrasonic frequencies.
Probability density of a frequency-modulated sound signal in a reverberant enclosure
Authors: Gammell Paul M. , Waterhouse Richard
Published: October 2005

One of the statistics of a random sound field in a reverberant enclosure is the distribution in time of the instantaneous sound pressure at a fixed point in space. Theoretical and experimental results are presented showing that this distribution tends toward Gaussian if the frequency modulated source contains a large number of sidebands at frequencies for which the responses of the enclosure are uncorrelated. The smallest frequency interval required for the responses to be uncorrelated is obtained from the autocorrelation function of the room response, which Schroeder showed to be related to the decay time of the room. It is the number of sidebands yielding substantially uncorrelated responses, rather than the number of sidebands having appreciable power, that determines the distribution.
Effects of intense auditory stimulation: hearing losses and inner ear changes in the chinchilla
Authors: Hunter-Duvar Ivan M. , Bredberg Göran
Published: October 2005

Following determination of normal audiograms, eight chinchillas were exposed to intense acoustic stimuli which produced permanent threshold shifts (PTSs). Four of the animals were exposed to narrow-band noise at an overall intensity of 123 dB for 15 minutes. The other four animals were exposed to a 1000-Hz tone at an intensity of 120 dB for durations sufficient to produce PTSs. Final thresholds were determined five weeks after exposure, after which animals were sacrificed and cochleas were fixed and prepared as surface specimens. Counts of missing or severly damaged hair cells were made for each cochlea. Animals exposed to noise had hearing losses ranging from 14 dB to greater than 45 dB. Anatomical damage ranged from no visible damage for the animal with the 14 dB loss to very severe damage for the animal with the 45-dB loss. Animals exposed to the 1000-Hz stimulus showed losses from 22 dB to greater than 45 dB. Lesions for this group ranged from 0.5 to 1.5 mm. The 12-min pure-tone exposure of chinchillas produced greater losses than seen in squirrel monkeys exposed 12 hours to the same stimulus.
Human auditory thresholds during deep, saturation helium-oxygen dives
Authors: Thomas William G. , Summit James , Farmer Joseph C.
Published: October 2005

Air-conduction and bone-conduction thresholds were derived on 33 different divers on eight saturation dives in helium-air between 300 and 1000 ft. A total of 400 air-conduction and 300 bone-conduction audiograms were given at 26 different depths during compression and decompression. The results indicate a reversible, depth-related conductive hearing loss. The shape of the audiometric function and absolute amount of hearing loss are somewhat different from data reported in hyperbaric air.
Some cues for syllable juncture perception in English
Authors: Christie William M.
Published: October 2005

Most previous acoustic research on syllable juncture phenomena has used as stimuli recordings of natural speech. From this research it has been possible to suggest that certain differences observed in spectrograms of the recordings might cue the differences in the perceived location of the syllable boundary, but confirmatory tests with synthetic stimuli have been lacking. This experiment uses synthetic stimuli to examine intervocalic /st/ clusters to determine the effects of formant transitions onto the /s/, silence between the end of the /s/ noise and the /t/ burst, and aspiration on the /t/ in determining the location of syllable boundaries in English. Formant transitions appear to have little or no effect on the boundary, but silence and aspiration both affect perception of the boundary location. The fact is noted that the aspiration on the /t/ is a feature of allophonic alternation in English. A proposal made earlier by Lehiste that allophonic alternations can carry structural information is thus confirmed by this experiment. Some suggestions for further research are appended.
Bandwidth limitations and analysis of cetacean sounds, with comments on “Delphinid sonar: measurement and analysis” [K. J. Diercks, R. T. Trochta, and W. E. Evans, J. Acoust. Soc. Am. 54, 200–204 (1973)]
Authors: Watkins William A.
Published: October 2005

Historically, recording of cetacean sounds has encompassed an ever-enlarging bandwidth as equipment has improved and repertories of sounds from each species have become better known. The effect of equipment bandwidth limitations on our knowledge of these sounds is discussed. Very short sounds whose components are above the bandwidth of the equipment nevertheless are recorded as low-level broad-band pulses. The distortions of transient pulses reported by Diercks, Trochta, and Evans [“Delphinid sonar: measurement and analysis,” J. Acoust. Soc. Am. 54, 200 (1973)] are suggestive of overload resonance and nonlinearity. The evidence does not seem to support the implication that these animals produce similar echolocation sounds in spite of different situations and tasks, or that lower-frequency emphases in their pulsed sounds are artifacts of limited bandwidth equipment.
Judgments and dimension analyses of perceived sound quality of sound-reproducing systems
Authors: Gabrielsson Alf , Rosenberg Ulf , Sjögren Håkan
Published: October 2005

In two experiments two or three subject groups—“listeners in general” (L), musicians (M), and “hi-fi subjects” (HF)—made evaluative ratings, similarity ratings, and verbal descriptions concerning different sound-reproductions of certain music sections. The reliabilities of the ratings were in general high. Interactions between reproductions and music sections appeared, giving different ratings/rankings of reproductions at different music sections. Some differences in ratings between the L group and the other groups were suggested. Dimension analyses revealed some dimensions as “distinctness,” “brightness,” and “loudness.” Other possible dimensions were suggested by the verbal descriptions.