bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient bulk-wave microsonic transducer
Authors: Brodwin Morris E. , Chou Kan
Published: October 2005

A microwave acoustic exciter is described which utilizes an efficient thin-film piezoelectric transducer in a re-entrant cavity configuration. Measurements of conversion loss by input impedance and pulse-echo methods yield a 2.5-dB one-way conversion loss at 1.58 GHz. The observed conversion-loss bandwidth is 20 MHz and is limited by the cavity resonance.
Reflection of an elastic wave at a free boundary in hexagonal metals
Authors: Henneke Edmund G.
Published: October 2005

Calculated reflection parameters for a quasi-longitudinal wave incident upon a stress-free boundary are presented for zinc, magnesium, and cadmium.
Coupled twist-bending waves and natural frequencies of multispan curved beams
Authors: Chen Shoei-sheng
Published: October 2005

A method for the analysis of the free waves and natural frequencies of continuous curved beams is presented based upon the use of the dynamic three-moment equation.
Reduction of noise generated by flow of fluid over plate
Authors: Pinkel Benjamin , Scharton Terry D.
Published: October 2005

This letter describes a method of reducing the noise generated by a fluid stream flowing subsonically over a plate and also presents some substantiating test data. This concept may prove useful for reducing the noise of STOL aircraft employing the externally blown flap or the augmenter wing, which configurations are now under exploratory development.
Some general reactions to Kryter's paper “Impairment to hearing from exposure to noise”
Authors: Cohen Alexander
Published: October 2005

Reactions offered here (a) urge rethinking on the adequacy of a widely used criterion for defining hearing handicap in view of data referenced in the subject report, (b) criticize the author's evaluations basic to estimating hearing loss risk from known levels of noise exposure and recommending safe limits for hearing, and (c) question the use of proposed complex schemes for rating noise hazards to hearing as derived from presumed relationships between temporary and permanent noise-induced threshold shifts in hearing.
Barrier-wall attenuation with a finite-sized source
Authors: Tatge R. B.
Published: October 2005

The computed attenuation afforded by an infinitely long barrier wall between a point source and a distant receiver has been extended to a source of finite size by considering it as a rectangular array of small equal closely spaced incoherent sub-sources. While one axis of the array is assumed to be vertical, it may have any angular orientation relative to the receiver and to the axis of the wall. If the source and wall are parallel, the high-frequency attenuation drops by 3 Db when the source-to-barrier spacing is doubled, and varies as 10 log (1 − h/H), where h is the source height and H is the height of the barrier.
Approximation for thin boundary layers in the sheared flow duct transmission problem
Authors: Eversman Walter
Published: October 2005

An inner expansion method is shown which allows an approximate solution for the problem of the transmission of sound in a duct containing a sheared flow in the case when the region of nonuniform flow is very thin. This method develops modified boundary conditions which account for the sheared flow layer but which can be employed with a conventional uniform-flow transmission, analysis to determine the wavenumbers and mode shapes for acoustic propagation and attenuation. Examples are given over a wide frequency range at several shear-layer thicknesses to validate the method and to indicate its limits of applicability. When applicable, the method offers potentially large computer-time savings over the commonly used Runge-Kutta integration-iteration approach.
Vapor bubble dynamics
Authors: Finch R. D. , Neppiras E. A.
Published: October 2005

The principles underlying the dynamics of a bubble filled with condensable vapor in a thermally conducting liquid are set out and the equations governing the radial motion of a spherical bubble in an unbounded liquid at a fixed temperature are derived. A linearized solution of these equations is then found, assuming harmonic acoustic drive. It is shown that the effective stiffness of the bubble is a complicated function of bubble radius and frequency; consequently it is possible for bubbles of two distinct sizes to resonate at the same frequency. Numerical values are presented for vapor bubbles in liquid Helium I, nitrogen, water, and for a liquid with the same effective thermal conductivity as liquid Helium II.
Bone-conduction thresholds of human teeth
Authors: Dahlin G. C. , Allen F. G. , Collard E. W.
Published: October 2005

Subjects with normal hearing were tested to determine thresholds of hearing when audio stimulation was applied to various teeth and the forehead at frequencies from 250 to 4000 Hz. The resulting data indicate that the teeth are more sensitive than the forehead by 5 to 10 dB in detecting the rms force applied. Comparison of the experimental results with recently published threshold values for the forehead and mastoid indicates that the teeth are comparable with the mastoid for audio sensitivity in bone conduction. This result, together with low measured power requirements, indicates that the teeth are an attractive site for the introduction of audio energy for hearing.
Torsional vibrations of shells of revolution of variable thickness
Authors: Soni S. R. , Jain R. K. , Prasad C.
Published: October 2005

Free torsional vibrations of conical and cylindrical shells of thickness varying as a power of distance have been discussed. The solutions depend upon a linear differential equation of second order. The governing equation is solved for shells with both edges fixed. The numerical values of the frequency parameter for the first three modes of vibration are computed for shells of linearly and parabolically varying thickness for several different ratios of terminal radii.
The interaural time jnd as a simultaneous function of interaural time and interaural amplitude
Authors: Domnitz R.
Published: October 2005

The interaural time jnd was measured as a simultaneous function of interaural time and interaural amplitude for 500-Hz tone bursts. It was found that the jnd was smaller when interaural amplitude and interaural time were arranged to produce subjective reinforcement rather than subjective cancellation.
Direct comparison of lateralization and the MLD for monaural signals in gated noise
Authors: Hafter E. R. , Carrier S. C. , Stephan F. K.
Published: October 2005

The lateralization model of Masking-Level Differences (MLDs) asserts that detection in those binaural conditions that produce an MLD is directly related to the perception of lateral space. The model was tested here by obtaining subjective reports of the lateral place of dichotic and diotic signals in noise which were in turn used by an “ideal observer” to determine the discriminability of the two classes of stimuli. The results support the model, showing that an observer using no information other than the lateralization judgments could detect NOSM in the dichotic condition as well as a subject who hear the acoustic stimuli.
Electret transducers: a review
Authors: Sessler G. M. , West J. E.
Published: October 2005

A review of the history, design, performance, and application of electret transducers is presented. Particular emphasis is placed on foil-electret transducers incorporating a thin-film electret made of Teflon or related materials. Such transducers have excellent frequency response, low distortion, small vibration sensitivity, and have been used over a frequency range extending from 10−3 to 2 × 108 Hz. They can be made in a variety of shapes over a large range of sizes and are generally not affected by adverse environmental conditions. More than 10 million electret transducers are being manufactured annually as microphones with various directivity patterns for use in amateur and studio applications, tape recorders, sound-measuring instruments, telephone-operators' headsets, hearing aids, and acoustic-graphic tablets, and as transducers in earphones and phonograph cartridges. Electret transducers are also used for experimental and research applications in such widely different fields as gas analysis, opto-acoustic spectroscopy, aeronautics, atmospheric studies, telephony, ultrasonics, acoustic holography, data transmission, and leak detection in space stations.
Noise-cancelling electret microphone for lightweight head telephone sets
Authors: Reedyk C. W.
Published: October 2005

The design of a small (0.8×0.5×0.2 in.) and light (1 g) noise-cancelling microphone based on the electret transducer is described. The microphone, mounted at the end of a boom, is used for a new operator's headset. The basic electret transducer is used as a first-order gradient microphone whose directional characteristic is adjusted so that, for a given bandwidth and background noise spectrum (speech from nearby operators), the noise-cancelling property is optimized. Pratical results indicating a minimum of 8 dB noise rejection are presented.
Optimization of a ridge backplate for electret microphones
Authors: Madsen H. S.
Published: October 2005

The desired properties for most microphones are high sensitivity, flat frequency response, insensitivity of response to vibration and temperature fluctuations, and long life. The life of an electret is particularly important since the self-polarization has a natural decay. It is possible, however, to design an electret microphone that has little variation in sensitivity even though the charge density of the trapped charges diminishes to 1/4 of its original value. This is possible by controlling every contributing parameter. The parameter that is hardest to control is the tension of the polymer diaphragm and the problem has been resolved by choosing a rectangular backplate with a diaphragm tensioned across parallel ridges. Stray capacitance and electrical load are among the parameters that affect the stability of the microphone, especially when the microphone becomes small as for a lightweight operator's headset. The results of computations and experiments are given.
The wave equation in a medium with a time-dependent boundary
Authors: Fortuin Leonard
Published: October 2005

It is shown that the Helmholtz equation is not exactly correct for a medium with a time-dependent boundary. The equation can be used with very good approximation when the time-derivative of the surface elevation is much smaller than the speed of the waves through the medium. For underwater sound waves, reflected and scattered by an ocean surface that can be described by the Pierson-Moskowitz spectrum, this means that the wind speed has to be much less than the sound speed.
Finite-amplitude acoustics of aerosols
Authors: Davidson G. A. , Scott D. S.
Published: October 2005

The evolution of finite-amplitude plane waves as they propagate through monodisperse aerosols of spherical particulate matter is investigated theoretically. Attenuation, dispersion, and the growth of higher harmonics are considered in detail. It is shown that, except for the case of very low dust-loading, the particulate matter dominates the gas self-viscosity in determining acoustic processes. Using a criterion based upon harmonic ratios, regimes of allowed and precluded shock-formation are tentatively identified and, in the case of the former, shock-formation distances are given. The shock-formation distance in an aerosol is shown to always be greater than that of the corresponding clean-gas case. Finally, the theory is extended to polydisperse systems. The results reduce to those of existing theories for the limiting cases of (i) infinitesimal-amplitude acoustics of dusty gases and (ii) finite-amplitude acoustics of clean gases.
Remark on “Fixed-scale mechanism of absolute pitch” [P. T. Brady, J. Acoust. Soc. Am. 48, 883–887 (1970)]
Authors: Corliss Edith L. R.
Published: October 2005

Several aspects of this author's subjective experiences concerned with perception of pitch are at variance with the experiences reported by Paul T. Brady, J. Acoust. Soc Am. 48, 883–887 (1970). In particular, my recognition is not tied to a specific scale (though, of course, nomenclature must be); the precision of recognition shows little fluctuation, if any; and changes in tuning do not influence the recognition of pitch, although such changes may influence the performance of remembered music and the ease of transposition. Tonal memory overrides motor memory for the performance of music learned on instruments tuned to initially different keys.
Unusual nerve-fiber distribution in the cochlea of the bat Pteronotus p. parnellii (Gray)
Authors: Henson Miriam M.
Published: October 2005

The distribution of nerve fibers in the osseous spiral lamina was examined in whole mount preparations of the cochleae of three species of bats which emit pulses containing both frequency-modulated (FM) and constant-frequency (CF) components: Pteronotus p. parnellii, Hipposideros diadema, and Rhinolophus ferrum-equinum. In Pteronotus the nerve-fiber population was extremely dense at the beginning and end of the large basal coil and relatively sparse between these areas. The striking contrast in nerve-fiber density seen in Pteronotus (family Mormoopidae) was not seen in the other two “CF/FM” bats (family Rhinolophidae).
Speaker identification in the absence of inter-subject differences in glottal source characteristics
Authors: Coleman Ralph O.
Published: October 2005

Speaker pairs can be identified as being composed of the same or two different speakers with better than 90% accuracy when the normal inter-subject differences in the glottal source characteristics are equalized. While between-subject differences in identifiability are relatively large, male speakers as a group retain a significantly greater degree of identifiability under the experimental conditions than do females.
Experimental demonstration of a viscoelastic “crossover” effect
Authors: Moffett Mark B.
Published: October 2005

Observations were made of the longitudinal strain pulses reflected from an interface between two viscoelastic rods. The incident medium (polystyrene) was nearly elastic, while the reflecting medium (unplasticized polyvinyl chloride) was fairly lossy, having a frequency-dependent, complex extension-wave impedance. The frequency at which the impedances of the two materials are equal in magnitude is termed the “crossover” frequency and is temperature-dependent. Fourier components well above the crossover frequency are reflected substantially in phase, while those well below this frequency are reflected nearly out of phase. By varying the temperature, and hence the crossover frequency, the reflected pulses were made to vary from essentially positive at room temperature to essentially negative at 55°C. At an intermediate temperature, the reflected pulse had a minimum amplitude and a shape significantly different from that of the incident pulse (this case is the viscoelastic analog of impedance matching for elastic media). The experimental results serve to demonstrate the viscoelastic-crossover effect predicted by Kolsky and Lee [Tech. Rep. No. 5, 562(30)/5, Div. Appl. Math., Brown Univ., May 1962].
Derivation of the multiple frequency Bessel-Fubini series via Fourier analysis of the preshock time waveform
Authors: Fenlon Francis Hugh
Published: October 2005

The nonlinearly generated spectral representation of a multifrequency CW acoustic source of finite amplitude, formed in a lossless nondispersive fluid medium, prior to the range at which shock formation occurs, is derived via the Fourier transform of an exact time waveform solution of the lossless Burgers' equation.
Lateral wave contribution to the underwater signature of an aircraft
Authors: McNicholas John V.
Published: October 2005

Urick's equipressure contours are modified by the contribution of the lateral wave to the pressure field. This contribution is shown to be significant at low values of the ratio receiver depth to source height.
Behavioral audiometry with the parakeet Melopsittacus undulatus
Authors: Dooling Robert J.
Published: October 2005

A technique which permits rapid determination of behavioral audiometric thresholds for pure tone in the parakeet (Melopsittacus undulatus) is described. A restrained bird was trained by avoidance conditioning and its threshold determined for 10 frequencies between 0.25 and 8.5 kHz.
Two-time methods applied to underwater acoustics
Authors: Solomon L. P. , Comstock Craig
Published: October 2005

A study is made of the problem of sound-wave propagation in a medium wherein the wave speed varies not only with position but also with time. We are interested in the problem where the time variation of the wave speed is very much slower than the frequency of the propagated wave. Our method is a perturbation method—the two-time or multiple scale method. Where the wave speed factors into the product of a time-varying term and a space-varying term, an explicit solution is obtained. In the more general case, a solution can also be obtained, but its validity can only be conjectured. The results of this paper have application to the problem of studying correlation of high-frequency signals over long periods in underwater sound propagation. Experimental studies have pointed out that amplitude and phase of a CW signal are modulated by the fluctuation frequency of the channel stratification. The technique we use appears to be successful but complicated. An extension of Lighthill's rule, which was originally developed for the Method of Strained Coordinates, is presented.
Aerodynamic sound and the low-wavenumber wall-pressure spectrum of nearly incompressible boundary-layer turbulence
Authors: Bergeron Robert F.
Published: October 2005

The low-wavenumber structure of fixed-frequency cross-spectral density of turbulent pressure fluctuations at a rigid plane boundary is determined for flows with small but finite Mach number. The method of matched asymptotic expansions is applied in the coordinate normal to the boundary. The boundary layer is an inner region, and prescribes an “effective” boundary velocity distribution for the outer region, which is governed by the acoustic wave equation. Those components of effective velocity with supersonic phase speeds account for the radiation of sound. For the inviscid infinite plate model, the wall-pressure spectrum has a nonintegrable singularity at the acoustic critical wavenumber. Because of undamped contributions to point pressure from distant acoustic sources, in fact, the infinite model fails in an inviscid medium with any degree of compressibility. A large but finite model is considered, and the nonintegrable singularity at the critical wavenumber is removed. The spectrum coincides otherwise with the infinite plate result. The finite extent of the model can represent either a real geometrical limitation or the effect of damping over long distances. The intensity in the radiated field is shown to vary with the eighth power of velocity, but with a coefficient proportional to the logarithm of the characteristic in-plane dimension.
The resolution of target range by echolocating bats
Authors: Simmons James A.
Published: October 2005

Using simultaneous discrimination procedures the acuity of resolution of differences in target range has been determined on four species of echolocating bats (Eptesicus fuscus, Phyllostomus hastatus, Pteronotus suapurensis, and Rhinolophus ferrumequinum). All can discriminate range differences as small as 1 to 3 cm and, for the first three species, the acuity of range resolution appears to be independent of absolute range, at least at short distances. In Eptesicus range discrimination mediated in terms of the arrival times of echoes returning from different targets. Comparisons between discrimination performance and autocorrelation functions of echolocation sounds used in the discriminations suggest that these bats possess some neural equivalent of a matched-filter, ideal sonar receiver which functionally cross-correlates a replica of the outgoing signal with the returning echo to detect the echo and determine its arrival time. Eptesicus and Phyllostomus both use the entire FM signal for target ranging. Pteronotus uses its entire compound, short-duration CF/FM signal for ranging, while Rhinolophus separates the FM component from its compound, long-duration CF/FM sound and uses the FM part for target ranging. The results indicate different functions for the CF and FM components of bat sonar cries, and they suggest that the matched-filter or cross-correlation approach to echolocation is appropriate.
Delphinid sonar: measurement and analysis
Authors: Diercks K. J. , Trochta R. T. , Evans W. E.
Published: October 2005

Problems in acquisition, storage, and analysis of delphinid echolocation signals are described and illustrated. It is shown that adequate bandwidth is the prime requisite for validity in measurement. However, idiosyncracies of the detector and recorder may alter the signal and, therefore, its derived characteristics. Uncertainty about the signal leads to ambiguous results in analysis.
Effect of ascending and descending measurement methods on comfortable loudness levels for pure tones
Authors: Woods Robert W. , Ventry Ira M. , Gatling Linda Wingate
Published: October 2005

The effect of ascending and descending measurement methods on comfortable loudness (MCL) levels for continuous and interrupted 1000-Hz pure tones was studied using Békésy audiometry and 20 normal-hearing adults. Ascending pure-tone MCLs were significantly lower than descending MCLs for both types of pure-tone stimuli with differences ranging from 12 to 30 dB. The relationship between MCLs obtained with continuous and interrupted stimuli was unaffected by measurement method.
Radiation from arbitrarily positioned circular pistons in an infinite baffle
Authors: Alper Stanley , Magrab Edward B.
Published: October 2005

An arbitrarily positioned array of circular pistons in an infinite rigid baffle having an acoustic fluid on one side is analyzed to determine the velocity of each piston and the total radiated pressure, both near- and farfield, when the acoustic-pressure interaction between all the pistons taken into account. The diameter of the pistons and the phase relations between each of the harmonically varying driving forces on the pistons are arbitrary as are the masses of the pistons and the mechanical parameters characterizing the piston assembly. The solution is obtained using oblate spheroidal coordinates and the principle of superposition to reduce the array problem to a collection of simpler problems. The expressions derived appear to have a computational advantage for computing both the velocity of the pistons and the nearfield and farfield pressures. The method can also be extended to two arbitrarily positioned circular elastic plates in an infinite baffle. Numerical results for the series solutions describing the pressure field and the mutual impedances are not given.
Attenuation of sound by schooled anchovies
Authors: Davies I. E.
Published: October 2005

A laboratory experiment is described in which acoustic attenuation through an aggregation of live anchovies was measured over the frequency spectrum 1–20 kHz. The fish were enclosed in a plexiglass sphere of 1.2-m3 internal volume, and the estimated population density during the test was 650 fish/m3. Maximum attenuation, greater than 20 dB, occurred from 6 kHz while the sphere was fixed between projector and hydrophone. Constant frequency runs were made at 3.5 and 10 kHz as the sphere was rotated through 360° in the path, and variations of the order of 15 dB were observed as fish aspect changed relative to the acoustic axis. Results were compared to theoretical values of attenuation for the size distribution and number of fish in the sample, and differences in both amplitude and frequency response were noted.
Cochlear Waves: Interaction Between Theory and Experiments
Authors: Zwislocki J. J.
Published: October 2005

Review of past experimental and theoretical research leads to a statement of our present knowledge of cochlear mechanics. In particular, an attempt is made at a clear definition of the nature of cochlear waves. With the help of prominent examples, it is shown that neither experiments nor theory have ever been entirely correct but have supplemented and corrected each other mutually in steps of successive approximation. As the approximation has become closer, the steps have become smaller, but the process is still going on. During the Békésy era, the weight of research was on the fundamental properties of cochlear waves; now, the emphasis is on numerical values of such parameters as wavelength, damping, and nonlinearity. At the end of the presentation, some effects of the cochlear wave pattern on auditory neural excitation are discussed. Especially, it is shown how displacement and velocity responses can be separated by means of appropriate stimulus patterns.
The sounds of St. Mary's
Authors: Fitzroy Dariel
Published: October 2005

Acoustical design criteria for the recently completed St. Mary's Cathedral, San Francisco, reflect current emphasis on improved speech communication, rather than the extreme reverberance traditionally characteristic of cathedrals. By judicious placement of absorption treatment, mid-frequency reverberation time was held down to 2.4 sec fully occupied or 4.0 sec empty, and the resulting environment was found to be most acceptable for organ and choral music. Good speech communication was achieved by an electronic reinforcement system that directed most of its energy toward the congregation without adding much to reverberant levels.
Loudness changes resulting from an electrically induced middle-ear reflex
Authors: Gunn Walter J.
Published: October 2005

An experiment was conducted in order to determine the changes in loudness brought about by electro-cutaneous elicitation of the middle-ear reflex. Subjects were required to judge the relative loudness of the second of three consecutive 30-msec bursts of tone, the second tone being accompanied by an electrical shock to the external auditory meatus, capable of eliciting a contraction of the middle-ear muscles. The difference between these judgments and those of the control condition (shock on the arm) was taken to represent a measure of the attenuation provided by contraction of the middle-ear muscles. Test tones were 500, 1000, 2000, and 3000 Hz at levels of 65, 75, 85, 95, and 105 dB (re zero hearing loss). The results indicate that the middle-ear reflex decreases the middle-ear's transmission mainly for low-frequency sounds. The results fail to lend support to the Loeb-Riopelle hypothesis that the middle-ear reflex acts as a limiter, rather than a linear attenuator. In fact, there was a small, but significant, decrease in attenuation with increasing auditory stimulus intensity at the higher frequencies.
Correlation model of binaural detection: interaural amplitude ratio and phase variation for signal
Authors: Osman Eli
Published: October 2005

Predictions of the correlation model of binaural masking-level differences (BMLDs) are presented for the class of experiments in which the noise waveforms at the two ears are identical, while the tonal-signal parameters for interaural amplitude ratio and interaural phase shift are varied. These predictions are compared to empirical data, and their relations to predictions of the equalization-cancellation model and a lateralization model are discussed.
Does radiation pressure depend on B/A?
Authors: Rooney James A.
Published: October 2005

Measurements were made of the radiation force on an absorbing target for the Langevin situation. Determinations of apparent change in weight of a target using an electrobalance were made in distilled water, n-propanol, and ethanol at a frequency of 5 MHz and acoustic power outputs in the milliwatt range. They indicate that within experimental error the Langevin radiation pressure is independent of B/A.
Experimental shadowing measurements on randomly-rough surfaces
Authors: Welton P. J. , Hawker K. E. , Frey H. G.
Published: October 2005

The dependence of the shadowing function on grazing angle was optically measured on three rough surfaces which are identical except for the rms reliefs (and slopes) which had been scaled in the ratios 1 : 2 : 4. Both one- and two-dimensional shadowing measurements were made. The one-dimensional measurements are in good agreement with the one-dimensional theory of shadowing developed by R. J. Wagner. In addition, the one- and two-dimensional shadowing measurements are in excellent agreement with one another as would be expected for nearly isotropic surfaces.
Volume backscattering in the Tasman Sea, the Coral Sea, and the Indian Ocean
Authors: Hall M.
Published: October 2005

Acoustic volume reverberation was measured at frequencies from 2.5 to 16 kHz at a number of stations in the Tasman Sea, the Coral Sea, and the north-eastern region of the Indian Ocean. The dependence of volume backscattering strength on time of day, acoustic frequency, and depth beneath the sea surface were investigated. In the Coral Sea and the Indian Ocean, the average diurnal variation increased with decreasing frequency; but in the Tasman Sea the diurnal variation was almost independent of frequency. The volume backscattering strengths generally increase with frequency, but nighttime spectra are usually flatter than daytime spectra. Deep-scattering layers were detected in the three areas at 40% of the daytime stations. Each of these DSL's had a single resonance frequency, 70% of them at 5 or 6 kHz. Most of the DSL's were at depths between 400 and 600 m. The results suggest that the volume reveration was due to backscattering by the swimbladders of mesopelogic fish.
Frequency dependence of the daily pattern of sea reverberation
Authors: Johnson R. K.
Published: October 2005

The diurnal variation of volume reverberation at frequencies from 3 to 30 kHz in the upper 600 m of the California current is analyzed. The variation is attributed to the vertical movements of resonant and nonresonant scatterers. A distribution model is developed which characterizes the sizes and population concentrations of six groups of scatterers.
Frequency dependence of thresholds for ultrasonic production of thermal lesions in tissue
Authors: Lerner R. M. , Carstensen E. L. , Dunn F.
Published: October 2005

The ultrasonic intensity threshold for producing lesions in mammalian brain tissue is not a strong function of frequency (over the range of 1–10 MHz) for exposures longer than 1 sec. A model is presented to explain this apparent lack of frequency dependence. It is assumed that the maximum temperature developed in the lesion volume for a given pulse duration is determined (1) by the absorption coefficient of that tissue, and (2) by the distribution of the acoustic intensity over the treated volume (sharpness of the beam). The former is observed experimentally to be nearly linearly dependent upon frequency in the range 1–10 MHz, and the latter, for a good lens, is related inversely to frequency. Temperature calculations which account for heat loss by diffusion as well as the frequency dependence for the beam geometry and the absorption coefficient are presented. These lead to nearly frequency independent curves for threshold dosages beyond 1-sec exposure, giving credence to the suggestion that thermal processes may be predominant for such exposures.
Random vibration of distributed systems strongly coupled at discrete points
Authors: Davies Huw G.
Published: October 2005

The response of two simple systems, such as beams or plates, strongly coupled at a point is discussed. Two models of a mass, spring, and gyroscopic coupling mechanism are treated. It is shown that the result of statistical energy analysis (SEA) relating power flow to differences in modal energy can be obtained even when the coupling is strong. For one model of the coupling mechanism, the power flow can be expressed in terms of changes in modal resonance frequencies caused by the coupling.
Reply to “Speaker identification by speech spectrograms: some further observations” [R.H. Bolt, F.S. Cooper, E.E. David, P.B. Denes, J.M. Pickett, and K.N. Stevens, J. Acoust. Soc. Am. 54, 531–534 (1973)]
Authors: Black John W. , Lashbrook William , Nash Ernest , Oyer Herbert I. , Pedrey Charles , Tosi Oscar I. , Truby Henry
Published: October 2005

In their letter to the editor, “Speaker identification by speech spectrograms: some further observations,” Bolt et al. [J. Acoust. Soc. Am. 54, 531–534 (1973)] express an opinion on voice identification as produced in real-life cases by specially trained professional examiners using a combined aural and visual examination of speaker samples. The opinion of these authors is not based on personal experience or even on a direct observation of these examinations. In addition, they disregard crucial facts that strongly interact with the reliability of those positive decisions produced by professional, full-time examiners, such as their special training and responsibility, the five possible decisions they are entitled to produce after each examination, the number of samples, and the length of time used to perform each examination. It is our contention that opinions based on feelings other than in actual experience are of little value, irrespective of the scientific authority of those who produce such an opinion.
On-line ultrasonic technique for monitoring tongue displacements
Authors: Watkin Kenneth L. , Zagzebski James A.
Published: October 2005

A pulsed, through-transmission ultrasound system for monitoring displacements of the tongue during speech production is outlined. The technique enables on-line recording of the position of a discrete element on the dorsal surface of the tongue. A simultaneous cinefluoroscopic ultrasonic study of tongue motions resulted in excellent agreement between ultrasound data obtained with this technique and corresponding data measured from cine films.
Anatomical correlates of deafness
Authors: Smith Catherine A.
Published: October 2005

Structural defects associated with deafness may be divided into two classes. The first class is associated with structures of the external and middle ear with the result that conduction of sound is impeded. Deformities of the external auditory canal and the ossicles may be hereditary and present at birth. Middle-ear infections, otosclerosis, etc., acquired later may alter normal ossicular chain function. In the second class, the pathology is restricted to the internal ear. If the defect is congenital, it may have been inherited, or occurred “in utero” such as with rubella infections. After birth, an individual may be exposed to any number of situations which cause destruction of the hair cells and the cochlear nerve fibers. If the loss is extensive enough, a defective receptor organ results, with partial or complete deafness of the individual. It is not clear at present precisely what percentage of hair cells and nerve fibers are necessary for adequate social communication, but there is no replacement of degenerated receptor cells or sensory nerve fibers.
Thresholds for click pairs masked by band-stop noise
Authors: Hall J. L. , Lummis R. C.
Published: October 2005

The auditory threshold was measured for a pair of clicks in the presence of band-rejected masking noise. This threshold depends on the interval between the two clicks. As the interval is changed, the threshold intensity alternately increases and decreases. For homopolar clicks and masking noise with a spectral gap centered at f Hz, maxima are at (2n +1)/(2f) sec (n = 0,1,2,…). Experimental determinations of this fluctuation, for equal-intensity clicks, are in quantitative agreement with predictions of a simple model. In the model, band-stop noise produces a band pass filtering of the click stimulus, and the stimulus is detected if the long-time average energy at the filter output exceeds some threshold value. However, if the clicks are of unequal intensity, the threshold is influenced by the click order. This order effect is inconsistent with the energy-detection model.
A quantitative study of cochlear potentials along the scala media of the guinea pig
Authors: Honrubia Vicente , Strelioff David , Ward Paul H.
Published: October 2005

The relationship between the parameters of pure-tone acoustic stimuli and those of the cochlear microphonics (CM) and summating potentials (SP) was studied for measurements from scala media in each of the four turns of the guinea-pig cochlea. For each turn similarities in the shapes of the input-output functions over a wide range of frequencies permitted adequate quantitative description of these functions by a single third-degree polynomial equation. Therefore, the properties of both cochlear potentials (CM and SP) can be described by a nonlinear transfer curve over the specified frequency range. These results imply the SP should not be regarded as being generated by a process different from the CM but as an expression of the nonlinear characteristics of the generator of cochlear potentials. At frequencies where the measuring electrode is near the peak of the mechanical traveling wave envelope, the transfer curve no longer described the cochlear potentials. Calculations based upon phase measurements and upon theoretical considerations indicate that this is due to interference effects from the out-of-phase generators in the vicinity of the electrode.
Detection of acoustic sources using long-wavelength acoustical holography
Authors: Watson E. Eugene
Published: October 2005

Sound sources from vibrating circular and ribbed rectangular plates are detected by holographic means using a microphone scanner and associated photographic equipment. Reconstruction of the wavefront from the acquired acoustical holograms reveals the areas on the plates which generate the far-field acoustic radiation. In all cases, the plates were driven below their coincidence frequency. The location of the sound sources on the plates supports the theory of acoustic radiation from complex vibrators except for irregularities which are due to inhomogeneities of the plate material, nonlinearities of the holographic technique, and the speckle effect.
Determination of the elastic constants of single crystals by means of free longitudinal vibrations
Authors: Zuckerwar Allan J.
Published: October 2005

A method is described for determining the elastic constants of a crystalline material from measurements of the first two longitudinal frequencies of long bars of rectangular cross section. The method is based upon the relationships between the elastic constants and both Young's modulus and the dispersion of longitudinal waves. The expression for the dispersion, derived with the aid of perturbation theory, is applicable to specimens of the most general (triclinic) anisotropy. The method yields the following values for the elastic compliances of silicon (in cm2/dyn × 1013): S11 = 7.704±0.4%, S12 = −2.234±2.8%, S44 = 12.692±2.5%. A self-consistency check yields S12 = −2.254±11.5%. These values are compared to those of other workers using high-frequency methods.
Acoustic measurements with a circular nearfield array in an anechoic water-filled tank
Authors: Groves Ivor D. , Benedetti Vincent P.
Published: October 2005

The measurement capability of a 2.5-m-diam anechoic steel tank for calibrating underwater electroacoustic transducers has been considerably increased by the installation of a nearfield transducer array. Because the boundary conditions required for valid measurements with the array are less restrictive than those that apply without the array, both the size of transducers and the frequency range of measurement are greater than was permissible formerly. Design criteria for the array are given. Data gathered from two years experience are presented to show the array's performance at 7 MPa (1000 psi) hydrostatic pressure and at the temperatures 3° and 25°C.
Sound propagation in wakes
Authors: King Walter F.
Published: October 2005

The two-dimensional stochastic equation for ray acoustics is used to study sound propagation in turbulent wakes generated by ocean-going vehicles. It is assumed that both surface and underwater wakes can be represented by two-dimensional axisymmetric refractive-index fields. Random inhomogeneities are included in the fields by stochastically varying the refractive index. Ray plots and intensity contours are presented for a number of typical wake configurations. The sound-channeling effect of wakes is clearly demonstrated.
Use of high-resolution pseudorandom noise signals to isolate individual underwater sound paths
Authors: Welser E. V.
Published: October 2005

In the course of the study of the transmission properties of broad-band pseudorandom noise signals as a function of range, water depth, and other environmental parameters, relationship between correlation peak time differences and multipath time differences was determined. Illustrations of the measured cross correlation between a reference and high-resolution pseudorandom noise signal versus time and calculated ray paths are presented. Peak correlation values range from 0.31 to 0.63 for the demonstration data. Only minor discrepancies were observed in the measured time differences between the correlation peaks and those calculated from XBT data.
Elliptical cylindrical liquid lens
Authors: Yeh C.
Published: October 2005

The problem of focusing a pressure wave by a thick, elliptical cylindrical liquid lens has been treated in a rigorous manner. The size of the lens is of the order of or slightly greater than the wavelength of the incoming acoustic signal. Detailed computation has been carried out for a representative case in which a liquid lens with an index of refraction of 1.8 and a density of 1900 kg/m3 is assumed to be immersed in seawater. It is shown that a slight deformation of the boundary surface of a circular liquid lens results in significant changes in the location of the focal region and that an elliptical lens may provide stronger focusing than an equivalent circular lens. This research also points out the necessity of pursuing an investigation on thin lenses where the focal regions are located outside the lenses.
Comparison of processing requirements in phased-array sonar and acoustical holography
Authors: Keating P. N.
Published: October 2005

The basic difference between phased-array sonar and acoustical holography lies primarily in the order in which the temporal and spatial processing operations are carried out. However, it is shown that this difference can result indirectly in an advantage for holography in either signal-to-noise performance or processing complexity.
New procedure for training chinchillas for psychoacoustic experiments
Authors: Burdick Charles K. , Miller James D.
Published: October 2005

Four chinchillas were trained to lick a drinking tube located in one end of a double-grille cage to obtain their daily ration of water. When the licking rate stabilized (4–5 licks/sec) in daily sessions of about 20 main, avoidance conditioning began. The animal was required to leave the tube and cross a midline barrier to avoid shock when one sound, the positive conditioned stimulus (+CS), was presented, while he could continue licking without threat of shock when another round, the negative conditioned stimulus (−CS), was presented. The chinchillas quickly learned a near perfect association of crossing the barrier to +CS and not crossing to −CS, which was maintained throughout the 30 daily sessions of the experiment. Intertrial crossing were virtually absent and licking rates provided a sensitive, additional measure of an animal's response to the stimuli
Frequency dependence of acoustic-wave scattering from randomly rough surfaces
Authors: Caruthers Jerald W. , Clark Douglas N.
Published: October 2005

Using numerical techniques presented in a previous paper [J. C. Novarini and J. W. Caruthers, J. Acoust. Soc. Am. 53, 876–884 (1973)], the statistical character of five acoustic fields in the range 0.75–3.00 kHz scattered from an ensemble of model sea surfaces for a wind speed of 4 m sec−1 is presented. Total intensity, degree of coherence, and phase and amplitude fluctuations are studied in the range of transition from a smooth to a rough surface.
Very deep scattering layer
Authors: Johnson R. K.
Published: October 2005

A scattering layer extending from 1200 to 1400 has been measured at two locations in the Pacific. Observations over a frequency range of 3 30 kHz indicate a scatterer population density of 25 per 106 m3. The target strengths of the scatterers are consistent with values calculated for a resonant gas bubble of 0.4-cm radius.
Polynomial interpolation of bandlimited signals
Authors: Grace O. D.
Published: October 2005

Polynomial interpolation of bandlimited signal, having bandwidth W Hz, is shown to be exact for the sample rate fs > π W in the limit of an infinite-order polynomial.
Generator potentials: are they identifiable from gross cochlear recordings?
Authors: Dallos Peter , Cheatham Mary Ann
Published: October 2005

Generator potentials are graded electrical responses that mediate the initiation of all-or-none discharges in the fibers of the auditory nerve. They presumably arise in the non-myelinated dendritic portion of the neurons. To date, these potentials have not been identified experimentally with certainty, even though suggestions about neural origin of some components of the summating potential (SP) have appeared in the literature [Davis et al., Proc. Nat. Acad. Sci. (1950); Kupperman, Acta Oto-laryngol. (1966); Dallos et al., Science (1970)]: We now wish to demonstrate that a negative component of the AVE SP (common-mode potential of the two perilymphatic scalae) might be a gross, remote, manifestation of the generator potential. This component behaves in a distinctly different fashion from other SP products when examined in the presence of secondary sound stimuli (masking), with variable duty cycle of the stimulus (adaptation), and during anoxia. [Supported by a grant from the NINDS.]
Effects of electrical potentials upon hair-cell function
Authors: Strelioff D. , Honrubia V.
Published: October 2005

Isolated lateral-line preparations from the African clawed toad Xenopus laevis were mounted in a special chamber permitting recording of neural activity during mechanical cupular displacements and/or application of electric potentials across the receptor. Stimuli of frequencies from 1 to 100 Hz were effective in producing phase-locked modulation of spontaneous neural activity. A sample of six fibers had thresholds for electrical and mechanical stimulation of 0.62 ± 0.032 mV p − p and 11.4 ± 17.8 μm p − p, respectively. Electrical and mechanical input-output curves had similar slopes (0.74 ± 0.12 and 0.82 ± 0.31, respectively). Responses in the two afferent fibers innervating the same stitch were 180° out of phase for mechanical stimuli but in phase for electrical stimuli, demonstrating that electrical stimulation produced negligible mechanical movements. Response activity during mechanical stimulation could be modulated by electric potentials, suggesting that both stimuli act upon the same stage of transduction. These results are consistent with the mechano-electrical hypothesis of hair-cell function. [Supported by grants from the Deafness Research Foundation and USPHS 08193.]