bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of pressure and assessment of cavitation for a 22.5-kHz intra-arterial angioplasty device
Authors: Makin Inder Raj S. , Everbach E. Carr
Published: October 2005

This study was performed to understand better the mechanisms of action of an (22.5 kHz) ultrasonic wire catheter device used to remove atheromatous plaque in diseased blood vessels (ultrasonic angioplasty). During a clinical procedure, the wire acts as an acoustic waveguide to transfer acoustic energy from a generator outside the body to the ball tip of the wire, which is inserted in the blood vessel. The acoustic field radiated by the vibrating ball tip (1.5- to 3.0-mm diameter), was mapped in a relatively large (600 L) water tank and compared to the field from a well-characterized simple source. A dipolelike radiation pattern due to the translating ball tip was observed. At low power settings, standing wave effects in a smaller cylindrical volume (200-mm diameter, 350-mm height), which was used to simulate anthropometric dimensions, increase relative to the larger tank measurements. The standing wave ratio is dependent upon the ρc characteristics of the medium and the dimensions of the volume, rather than on the absorption at this frequency. At high power settings of the device, cavitation at the tip of the wire was measured using a 20-MHz passive cavitation detection scheme.
Sound production of gray whales, Eschrichtius robustus, along their migration route: A new approach to signal analysis
Authors: Crane Nicole L. , Lashkari Khosrow
Published: October 2005

Sound production of gray whales was investigated to determine their acoustic repertoire along the migration route, and to compare sound production in deep and shallow water. Recording was conducted off Monterey Bay and Carmel Bay, California, during the annual migrations of 1988 through 1991. Sounds were analyzed through digital signal processing. Six acoustic variables were measured. Three variables were used for final classification, chosen for their clarity in the presence of high levels of ambient noise (poor signal-to-noise ratio). These variables were 3-dB bandwidth, center frequency, and harmonic/sideband interval. Q ratio was used as an indicator of how broadband or narrow band a signal was relative to other gray whale signals. Four categories of signals were determined: M1, M3, M4, and M5. All signal types were concentrated below 1500 Hz. M3 signals had the lowest center frequency, averaging below 100 Hz. M1 were pulses and bonging signals, M3 were low-frequency moans, M4 were grunts, and M5 were subsurface exhalations. The rate of sound production was lower when whales traveled over deep water than over shallow water. Rate of sound production was less along the migration route compared to the lagoons. M3 signals were the most common, comprising 46.6% of the repertoire along the migration route, with M1 signals comprising 37.4%.
Computation of the diagonal matrix elements of the discretized Helmholtz integral equation
Authors: Wong Seung Kai
Published: October 2005

Analytic formulas are given for the diagonal matrix elements (sometimes called the ‘‘self-terms’’) which arise in discretizing the Helmholtz integral equation for acoustic radiation and scattering off an arbitrary surface. In terms of the coefficients of the first and second fundamental forms of the surface, the formulas are valid to leading order in the smallness of the surface element with respect to the characteristic dimension of the surface and the acoustic wavelength.
Lateral position of dichotic pitches can be substantially affected by interaural intensitive differences
Authors: Grange Anthony N. , Trahiotis Constantine
Published: October 2005

Using an acoustic pointer, three listeners matched the intracranial position of dichotic pitches presented with interaural intensitive differences (IIDs). Unlike data previously reported [Raatgever, ‘‘Binaural time processing and time-intensity trading,’’ in Psychophysics, Physiology, and Behavioural Studies in Hearing, edited by G. van den Brink and F. A. Bilsen (Delft U.P., Delft, The Netherlands, 1980), pp. 425–453], the intracranial position of the dichotic pitch image was moved substantially by IIDs. When the dichotic stimuli were presented continuously and turned off only when the listeners used the acoustic pointer, one listener produced data like those previously reported by Raatgever. Consequently, in terms of lateralization, it does not appear necessary to maintain a theoretical cleavage between images produced by dichotic pitches (previously thought to be influenced only by ITDs) and images produced by other binaural stimuli.
Temporary threshold shift in a harbor seal (Phoca vitulina)
Authors: Kastak David , Schusterman Ronald J.
Published: October 2005

During in-air auditory threshold testing, a harbor seal was inadvertently exposed to broadband construction noise for 6 days, averaging 6 to 7 h of intermittent exposure per day. When tested immediately upon cessation of the noise, a temporary threshold shift (TTS) of 8 dB at 100 Hz was evident. In addition, the animal’s false alarm rate increased from 7% in the pre-exposure session to 30% in the post-exposure test session. Following 1 week of recovery, the subject’s threshold was within 2 dB of its original level, and the false alarm rate was less than 10%. The data suggest that TTS can be induced in seals, and that our subject may have suffered from tinnitus, resulting in a reduced ability to distinguish signal-present from signal-absent trials.
Electroseismic wave properties
Authors: Pride Steven R. , Haartsen Matthijs W.
Published: October 2005

In a porous material saturated by a fluid electrolyte, mechanical and electromagnetic disturbances are coupled. The coupling is due to an excess of electrolyte ions that exist in a fluid layer near the grain surfaces within the material; i.e., the coupling is electrokinetic in nature. The governing equations controlling the coupled electromagnetic-seismic (or ‘‘electroseismic’’) wave propagation are presented for a general anisotropic and heterogeneous porous material. Uniqueness is derived as well as the statements of energy conservation and reciprocity. Representation integrals for the various wave fields are derived that require, in general, nine different Green’s tensors. For the special case of an isotropic and homogeneous wholespace, both the plane-wave and the point-source responses are obtained. Finally, the boundary conditions that hold at interfaces in the porous material are derived.
Two-dimensional acoustical diffraction by a penetrable wedge
Authors: Davis Anthony M. J.
Published: October 2005

A problem that has consistently defied rigorous analysis is the construction of the time-periodic Green’s function for an acoustic line source in the presence of a penetrable wedge with distinct wave speed. This paper begins by noting that in the ‘‘soft’’ limit (density ratio becoming zero) the interior field must become null and hence it is sensible to express the required Green’s function as a series in powers of the density ratio. Applications of Green’s theorem then reduce the problem to a sequence of integral equations for the determination of the coefficients in a similar expansion of the normal velocity at the wedge boundary. The exterior ‘‘hard’’ Green’s function now appears as the kernel while the interior hard Green’s function appears in the forcing terms to take account of penetration into the wedge. After observing that the velocity coefficients can be calculated recursively in terms of the solution of a single integral equation of the first kind, the latter is itself transformed to an equation of the second kind by using a known technique for Hankel function kernels. Some geometrical acoustics features of the solution are described and a method for subsequently determining the far field scattering pattern is given.
Scattering of acoustic and elastic waves using hybrid multiple multipole expansions—Finite element technique
Authors: Imhof Matthias G.
Published: October 2005

In this paper, two different methods to solve scattering problems in acoustic or elastic media are coupled to enhance their usefulness. The multiple multipole (MMP) expansions are used to solve for the scattered fields in unbounded homogeneous regions. The finite element (FE) method is used to calculate the scattered fields in bounded, heterogeneous regions. Applying the boundary conditions, the different regions and methods are coupled together in the least squares sense as the MMP method requires. By construction, the scattered field in the homogeneous regions is decomposed into P and S modes for the elastic case. In some examples, the scattered fields are calculated and compared to the analytical solutions. Additionally, the seismograms are calculated for a few scattering problems with one or several heterogeneous scatterers of complex geometries. The hybrid MMP–FEM technique proves to be a rather general and useful tool to solve complex, two-dimensional scattering problems.
The Green’s function for surface acoustic waves: Comparison between theory and experiment
Authors: Mourad A. , Desmet C. , Lauriks W. , Coufal H. , Thoen J.
Published: October 2005

The transient displacement of the surface acoustic wave caused by a transient impulse line source on a sample consisting of a substrate covered by a thin layer is calculated. Starting from the Green’s tensor for an anisotropic semi-infinite half-space, the layer, which will introduce dispersion, is considered as a perturbation of this half-space. Numerical results and experimental data, obtained with an all-optical technique, for an isotropic layer on an isotropic half-space are compared and show good agreement.
Uncertainties associated with noise dosimeters in mining
Authors: Giardino Dennis A. , Seiler John P.
Published: October 2005

The accuracy of an occupational noise exposure measurement, obtained by the use of a personal noise dosimeter, is commonly specified as being within ±2.0 dB. Using data obtained from an acoustical instrument calibration program, a study on microphone placement effects, representative noise spectra found in the mining industry, and the statistical method of propagation of error, an analytical model is proposed and an estimate of the errors in a real-world noise dosimeter measurement are presented. The findings of this investigation suggest that in a real-world environment, the noise dosimeter can deviate from the true noise dose, however, this noise dose estimation will usually be well within the commonly specified limits of ±2.0 dB, provided the measurements are made in a diffuse field, or in the case of a free-field measurement, the dosimeter microphone is placed on the shoulder of the most exposed ear.
Transducer transient suppression: Generalized methods of analysis
Authors: Piquette Jean C. , Forsythe Stephen E.
Published: October 2005

Generalized methods for determining the required waveshape for the driving-voltage waveform that produces no transients in the sound field radiated from an electroacoustic projector are presented. The methods described yield exact analytical expressions for the transient-suppressing drive for any equivalent circuit composed exclusively of lumped elements, although their practical numerical realization requires approximations to be made. However, the approximate drive so obtained can be chosen to approach the exact drive arbitrarily closely. An approximate method for transient suppression, based on z-plane analysis, is also presented. Although only approximate, the method does not require an equivalent circuit for the transducer of interest, but only an approximate z-plane representation. The method also has the advantage of producing no undesirable ramps or pedestals in the transient-suppressing drive.
Damping characteristics of thick rectangular laminates
Authors: Taylor Timothy W. , Nayfeh Adnan H.
Published: October 2005

The analysis for the exact three-dimensional viscoelastic solution for simply supported, thick rectangular laminates is developed. Each lamina is assumed to possess orthotropic or higher material symmetry and to be perfectly bonded to adjacent lamina. The damping capacity, or loss factor, of the laminate is derived from the exact three-dimensional elasticity solution using energy principles, allowing the analysis of arbitrary through-the-thickness geometry for the laminate. The damping characteristics of the laminate, as well as its natural modes of vibration, are obtained with the aid of the matrix transfer method. The matrix transfer method simplifies the requisite analytical developments as well as speeding the numerical calculations. The solution is compared with previous approximate thin-plate and discrete layer theory solutions. The damping capacity of the laminate is investigated as a function of modal frequency, plate thickness aspect ratio and total bonding layer thickness ratio.
Acoustic absorption due to proton transfer in solutions of proteins, peptides and amino acids at neutral pH
Authors: Holmes A. K. , Challis R. E.
Published: October 2005

Measurements of ultrasonic absorption in the frequency range 2 to 60 MHz have been made on solutions of the amino acid histidine, dipeptides glycyl tyrosine and histidyl tyrosine, and proteins lysozyme and bovine serum albumin. Measurements were carried out at 37 °C and covered the pH range 6.8 to 7.7. Mechanisms for the observed excess acoustic absorption involving bimolecular and intramolecular proton transfer are considered.
On the amplitude- and frequency-modulation decomposition of signals
Authors: Loughlin Patrick J. , Tacer Berkant
Published: October 2005

In general, the problem of determining the amplitude and frequency modulations (AM and FM) of a signal is ill posed because there is an unlimited number of combinations of AM and FM that will generate a given signal. Although Gabor proposed a method for uniquely defining the AM and FM of a signal, namely via the analytic signal, the results obtained are sometimes physically paradoxical. In this paper, four reasonable physical conditions that the calculated AM and FM of a signal should satisfy are proposed. The analytic signal method generally fails to satisfy two of the four conditions. A method utilizing the positive (Cohen–Posch) time-frequency distribution and time-varying coherent demodulation of the signal is given for obtaining an AM and FM that satisfy the four proposed conditions. Contrary to the accepted definition, the instantaneous frequency (i.e., the FM) that satisfies these conditions is generally not the derivative of the phase of the signal. Rather, the phase is separated into two parts, one which gives the instantaneous frequency via differentiation, and the other which can be interpreted either as phase modulation or quadrature amplitude modulation of the signal. Examples are given for synthetic signals and speech, with comparisons to the analytic signal method.
Is the pressure difference between the oval and round windows the effective acoustic stimulus for the cochlea?
Authors: Voss Susan E. , Rosowski John J. , Peake William T.
Published: October 2005

The assumption that the pressure difference between the cochlear windows is the stimulus that produces cochlear responses is tested experimentally in the ears of anesthetized cats. Cochlear potential is used as a measure of cochlear response. The sound pressures at the oval and round windows are individually controlled with both pressures at the same frequency and amplitude. When the angle difference between the two pressures is varied over one cycle, cochlear-potential magnitude varies by about 40 dB, with a sharp minimum occurring with the angle difference near zero. A linear model of the response to the two input pressures estimates a complex common-mode gain C and a complex difference-mode gain D; |D| is about 35 dB greater than |C| over the frequency range that was tested (75 to 1000 Hz). Thus, except for conditions that make the common-mode input much larger than the difference-mode input, the pressure difference between the oval and round windows is, to a good approximation, the effective acoustic stimulus for the cochlea.
Visualization of the onset of distortion-product otoacoustic emissions, and measurement of their latency
Authors: Whitehead M. L. , Stagner B. B. , Martin G. K. , Lonsbury-Martin B. L.
Published: October 2005

This paper describes a method for visualization of the onset of distortion-product otoacoustic emission (DPOAE) waveforms in the time domain. The DPOAE waveforms are obtained using ensemble averaging of samples of microphone output. A rectangular sample window is used, and the primary tones are turned on within the sample window. The phases of the primary tones (f1 and f2) are varied systematically between samples in such a way that the primary tones, and all DPOAEs (e.g., 2 f2−f1, 3f1−2 f2, 2 f1), except the DPOAE of interest (e.g., 2 f1−f2), are cancelled in the ensemble average. Visualization of the DPOAE onset allows measurement of the onset latency (OSL) of the DPOAE. These direct measurements of OSL are compared to phase-gradient latencies (PGLs) in the same ears determined by measuring the phase change of the DPOAE as a function of DPOAE frequency. The direct measures of OSL vary from ≳10 to <1 ms, decrease with increasing frequency and increasing stimulus level, and are shorter in rabbits than humans. The direct measures of OSL are, in general, quantitatively similar to PGL estimates, but there are exceptions. Visualization of DPOAE onset also allows quantification of DPOAE rise times, and reveals phase and amplitude changes of the DPOAE that occur several milliseconds after onset in rabbits and humans. It is proposed that the phase and amplitude changes result from vector summation of multiple components of the DPOAE signal, each with a different latency.
Medial efferent inhibition produces the largest equivalent attenuations at moderate to high sound levels in cat auditory-nerve fibers
Authors: Guinan John J. , Stankovic Konstantina M.
Published: October 2005

Previous work has shown that medial efferents can inhibit responses of auditory-nerve fibers to high-level sounds and that fibers with low spontaneous rates (SRs) are inhibited most. However, quantitative interpretation of these data is made difficult by effects of adaptation. To minimize systematic differences in adaptation, efferent inhibition was measured with a randomized presentation of both sound level and efferent stimulation. In anesthetized cats, efferents were stimulated with 200/s shocks and auditory-nerve-fiber responses were recorded for tone bursts (0–100 dB SPL, 5-dB steps) at their characteristic frequencies. Below 50 dB SPL, efferent inhibition (measured as equivalent attenuation) was similar for all fibers with similar CFs in the same cat. At 45–75 dB SPL, low-SR and medium-SR fibers often showed much larger inhibition, and substantial inhibition even at 100 dB SPL. Expressed as a fractional decrease in rate, at 90–100 dB SPL the inhibition was 0%, 6%, and 13% for high-, medium-, and low-SR fibers (differences statistically significant). Finding the largest equivalent attenuations at 45–75 dB SPL does not fit with the hypothesis that medial-efferent inhibition is due solely to a reduction of basilar-membrane motion. The large attenuations, some over 50 dB, indicate that medial efferent inhibition is more potent than previously reported.
Auditory filter asymmetry at 2000 Hz in 80 normal-hearing ears
Authors: Wright Beverly A.
Published: October 2005

Auditory filter asymmetry, bandwidth, dynamic range, and efficiency was measured at 2000 Hz in both ears of 40 naive, normal-hearing adults, counterbalanced for sex and initial ear tested. The filters were measured with 200-ms tonal signals temporally centered in 300-ms maskers. The maskers were notched noises presented at a spectrum level of 40 dB SPL. Quiet thresholds for the signal were also obtained. The distributions of the measured variables and correlations between them are reported. The average filter was nearly symmetric but the most common filters had steeper upper slopes. The shapes of the two sides of the filter were independent. Filter asymmetry was not correlated with the equivalent rectangular bandwidth (ERB), and quiet threshold was not consistently correlated with the dynamic range of the filter or with ERB. The mean ERB was 255 Hz.
Attention cueing aids auditory intensity resolution
Authors: Ward Lawrence M. , Mori Shuji
Published: October 2005

Intensity resolution of pure tones in a one-interval forced-choice paradigm was measured for experienced musicians under fixed- and uncertain-frequency conditions, and under uncertain-frequency conditions with informative cues as to target frequency. The uncertain frequency effect for intensity resolution, when present, was reduced or removed by frequency cueing, both with auditory stimulus cues and with visually presented information cues. Also, intensity resolution performance improved over the course of the experiment, both for fixed- and for uncertain-frequency conditions, as had been found previously. Analysis of the individual data indicated that across-experiment learning was unrelated to the ability to use the auditory stimulus cue, and that multiple-band learning was incompatible with the use of the visual information cue. The results are consistent with the idea that the single-band listening observed in fixed-frequency conditions was induced in most listeners by the auditory stimulus cue, but that some listeners chose to use the visual information cue to single-band listen while others ignored it and used multiple-band listening in that condition.
On the use of the normalized correlation as an index of interaural envelope correlation
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2005

The purpose of the present study was to obtain new empirical observations that would help determine the form of interaural envelope correlation that accounts for listeners’ sensitivity to binaural information conveyed by high-frequency stimuli. In a four-interval, two alternative task, listeners detected which interval contained a 4-kHz tone added antiphasically to diotic, 200-Hz-wide noise (NoSπ). The ‘‘nonsignal’’ intervals contained the tone added homophasically (NoSo). Discriminability (d′) was measured as a function of S/N for values between −30 and +30 dB. For all S/Ns, overall level was 70 dB SPL. Using a similar procedure, listeners were also tested in ‘‘direct’’ discrimination tasks where changes in envelope correlations were produced in one of two manners. First, changes in the normalized interaural envelope correlation were produced by varying the degree to which the envelopes covaried. This was accomplished by ‘‘mixing’’ two independent Gaussian noises. Second, changes in the normalized interaural envelope correlation were produced by adding dc values to the envelopes of the stimuli. Overall, in both experiments, listeners’ ability to discriminate changes in interaural envelope correlation (from a base correlation of 1.0) was well accounted for by the normalized correlation. It is also shown that the normalized correlation of the envelope accounts for classic data concerning discriminability of interaural time differences at high frequencies as a function of depth of modulation.
Recognition of concurrently-sounding musical instruments with different fundamental frequencies
Authors: Sandell Gregory J. , Darwin Christopher J.
Published: October 2005

The ‘‘double vowel’’ paradigm [P. F. Assmann and Q. Summerfield, J. Acoust. Soc. Am. 88, 680–697 (1990)], in which recognition for two concurrently-sounding vowels is measured over various fundamental frequency (F0) separations, is applied to natural musical instrument sounds. The findings of the previous work, in which recognition reaches peak by 1 to 2 semitone difference, is replicated here, with about 35% greater accuracy overall for musically experienced over naive listeners. Attention is given to special cases of instruments that are frequently confused for one another even whenF 0 separations are wide (e.g., clarinet and English horn, or flute and French horn), since such combinations may have special value in musical orchestration. In another condition, concurrently sounding instruments are adjusted in level by listeners so the two sound equally salient. The double-timbre study is then run with variable relative levels between the two instruments. Translations between the effects of semitones separation and difference in level are explored.
Sea-surface roughness effect on underwater coherent acoustic communications
Authors: Al-Kurd Azmi A.
Published: October 2005

The ocean represents a band-limited, temporally unstable multipath, and rapidly fading communication channel. Although the joint implementation of an adaptive decision feedback equalizer and phase-locked loop synchronizer updates the receiver filter coefficients to offset the signal error introduced by the time-varying channel transfer function, the effects of the temporal variation on the symbol rate and bit error rate have not been quantitatively investigated. This is because several oceanographic processes with inherently different temporal and spatial scales are simultaneously contributing to the amplitude and phase fluctuations of the signal; these factors are not easily isolated in the received data. In this study a full-field wave propagation code is used to simulate the transfer function for a temporally varying oceanic waveguide. An exact and approximate methods are being used to compute the rough surface scatter. The signal intensity and phase fluctuation statistics are investigated, and the effect of the magnitude, spatial coherence, and temporal variabilities of the surface roughness on the maximum communication data rate and the average bit error rate are being evaluated.
Underwater acoustic tracking in shallow water for naval training ranges
Authors: Stein Peter J. , Euerle Steven E. , Menoche Richard K. , Janiesch Robert E.
Published: October 2005

During the next several years the U.S. Navy will be installing large-area O (1500 km2) shallow-water training ranges off the U.S. mainland. These ranges require underwater acoustic tracking of targets to an accuracy of 100 m. Tracking will be performed via high-frequency (10–50 kHz) pingers located on the targets and bottom-mounted hydrophones (nodes). Traditional multilateral techniques, which require detection and decoding of the track ping at a minimum of three nodes, is not cost feasible. This is due to the limited propagation distance and the large number of nodes required. Another problem is potential damage to the nodes due to fishing operations. Recent experimentation has focused on unique solutions to these problems. These include bearing determination from a single node with a minimum number of sensors O(4) and concrete and steel underwater horns. The influence of the acoustic propagation and SNR on these systems is actively being investigated. Considerable high-frequency propagation data sets in shallow water have been collected and are being analyzed. The systems installed and the data collected will be described. Results of on-going analysis will be presented. Results point to a cost feasible engineering design which satisfies the Navy’s needs.
Target detection in a shallow-water environment using pseudorandom bipolar phase coded pulses
Authors: Commander Kerry W. , Croft Robert V.
Published: October 2005

Recent experiments with the Littoral Sea Mine Test Vehicle (LSMTV) have provided a direct comparison of the performance of pseudorandom bipolar phase coded (BPPC) pulses for use in detection and localization of near-surface shallow-water targets. A February 1996 experiment at Ft. Lauderdale utilized a triplane of known target strength and position to evaluate various BPPC pulses with different Doppler and range resolutions. The purpose of this experiment was to measure the signal-processing gain by these pulse types against slow moving targets (1–3 kn) and compare it with the theoretical values for this environment. The target return was immersed in a white Gaussian noise background with volume and surface reverberation. Runs were made with the LSMTV on the ocean floor at 535 ft and triplane depths of 50 and 110 ft. The range craft was positioned so that it would drift through the test area. This study evaluates the resolution performance of these BPPC pulses via direct comparison to 0.5- and 32-ms cw pulses against the same target by sequencing the pulses during each target opportunity. Comparative performance results are presented for the measured signal processing gains and resolutions versus theoretical calculations. [Work supported by ONR.]
Inversion in shallow water using the Wentzel–Kramers–Brillouin modal condition
Authors: Shang E. C. , Wang Y. Y. , Sun Shaobo
Published: October 2005

In this paper, an efficient scheme for extracting the complex bottom reflection coefficient (phase and amplitude) in a shallow-water waveguide by using the Wentzel–Kramers–Brillouin (WKB) modal condition is proposed. The input data are the measured modal wave number (km) and the modal attenuation (βm). The main advantages of this scheme are (1) it is efficient, because there are no replica calculations as in the conventional matched-field processing (MFP) scheme; (2) the inverted error induced by the ‘‘noise’’ of the contaminated data can be estimated analytically; and (3) the impact of the environmental (SSP) mismatch can also be estimated analytically. Numerical simulations illustrate that the proposed scheme works well in different scenarios of shallow-water waveguides. [Work supported by ONR and NOAA.]
Acoustic propagation experiments in the Hudson Canyon: Inversions
Authors: Rajan Subramaniam D. , Doutt James A. , Carey William M.
Published: October 2005

In September 1988 a series of acoustic propagation experiments was conducted in the Hudson Canyon area. It included a synthetic aperture experiment in which a source which transmitted a set of four pure tones was towed toward/away from a vertical array of receivers. The data obtained at 50 and 175 Hz are used to determine the compressional wave-speed profile for the bottom using the modal inverse method. The ability of the inferred model to predict the measured field at 50 Hz and at other higher frequencies is examined. Further, the applicability of the model to a contiguous area is examined to investigate the range-dependent nature of the bottom in the region. [Work supported by ONR.]
Use of angular correlation functions for detection of buried objects
Authors: Rajan Subramaniam D. , Zhang Linghong , Tsang Leung , Kuga Yasuo
Published: October 2005

In recent studies conducted on scattering of EM waves by rough boundaries, it has been shown that the angular correlation function obtained by correlating the scattered field at two incident angles has a high value along a line (‘‘memory line’’) governed by the incident and scattering angles. This approach is applied to the acoustic counterpart, and the ability of this method to discriminate clutter caused by the rough surface from that caused by partially or fully buried objects in the ocean bottom is investigated.
Case studies of design applications of impulse response tests
Authors: Siebein Gary W. , Gold Martin A. , Herr Christopher R. , Lilkendey Robert M.
Published: October 2005

Five case studies of applications of scale model impulse response tests on actual building projects will be presented to illustrate the ways that these methods can become an integrated part of the architectural design process. Case study 1 explores the acoustical and architectural design for the basic shape of a vaulted ceiling in a small auditorium. Case study 2 examines the refinement of balcony details in an 1800-seat performing arts facility. Case study 3 examines the changing of a small portion of the rear wall of an historic concert hall. Case study 4 examines the acoustical effects of sound propagation through an acoustically transparent lattice in a large concert hall. Case study 5 examines propagation of noise into a community from a partially enclosed, open-air firing range. The use of the impulse response tests in each of these instances provided the design team with a mechanism to enhance the understanding of the team members of the acoustical phenomena in question. The results of these studies point to the need for additional research to build a more direct link between the complex impulse responses heard in actual rooms and the acoustical qualities of the rooms. [Work supported by NSF.]
Mechanism of sound absorption by seated audiences in concert halls
Authors: Hidaka Takayuki , Nishihara Noriko , Beranek Leo L.
Published: October 2005

First, a prediction of the sound absorption of seated audiences in four concert halls was made by three methods. Employed were: reverberation chamber data obtained at the laboratory by the Kath and Kuhl method [Acustica 15, 127 (1965)] and the ISO-354 method on similar seating, and average absorption coefficients derived from RT data in 15 halls with three levels of upholstered seating [Beranek, Concert and OperaHalls , Acoustical Society of America, Woodbury, NY, 1996]. For each of the four halls, the residual absorption coefficients were determined from actual measurements (‘‘residual‘‘ meaning that due to all surfaces other than the seating). When the coefficients from the three methods and the measured residual coefficients were substituted in the Sabine equation, the K&K method gave the best prediction above 500 Hz and the Beranek method below 1000 Hz. In order to explain the large differences between K&K/ISO and actual hall measurements at the lower frequencies and to construct a method for predicting RTs in halls from reverberation chamber data, the difference in diffusivity in large concert halls and a reverberation chamber was examined. The incident angle distribution of sound rays onto a seated audience was determined by computer simulation and the oblique incident absorption coefficients of seated audiences were measured in an anechoic room. These findings were then employed to explain the large discrepancy.
An acoustical design criterion for balcony configuration in auditoria. II. A consideration on the directional characteristics of early reflections by computer simulation
Authors: Furuya Hiroshi , Fujimoto Kazutoshi
Published: October 2005

The object of this study is to make clear the relation between the shape of balcony and acoustical properties under the overhang, and to derive a design criterion for balcony configuration in auditoria. Impulse responses were calculated in models of auditoria by means of computer simulation based on geometrical acoustics when the depth and the height of balcony opening were varied. The directional characteristics of early reflections were examined in order to evaluate the lack of auditory envelopment, which was often perceived under the overhang. As a result, it was found that the ratio of the vertical component to total early reflection energy ERV was abruptly reduced under the balcony in comparison with that in the main orchestra and was closely related to the balcony index of d/h through the regression expression, where d/h was geometrically defined by the positions of sound source, receiving point, and balcony edge. Applying the difference limen of ERV to this relation, the maximum limit ofd /h, within which the degree of auditory envelopment perceived under the overhang was equivalent to that in main orchestra, was obtained between 0.7 and 1.0.
Determination of the reverberation time in any point of a closed room by a physico-mathematical model based on geometric acoustics
Authors: Marín Albert , Giménez Alicia
Published: October 2005

The determination of the reverberation time in a model based on geometric acoustics, which uses acoustic pressure and particle speed represented by means of phasors as working variables, is presented. Let p1⋅⋅⋅pm be the pressure waves that reach the receiver in orderly instances t1⋅⋅⋅tm, let p0 be the phasor sum of them; and let L0 be the corresponding equivalent level. The levels
A physico-mathematical model for the design and analysis of acoustic rooms
Authors: Marin Albert , Giménez Alicia
Published: October 2005

A model for the determination of an acoustic field in a closed room with several sound sources is presented. In this model the sound source is divided into sound rays, which are followed in the room, with these characteristics: (1) The sound pressure and the particle speed are the working variables used, so that calculating the most important qualification parameters of a room is possible; (2) the ray emission from the source is done randomly; (3) the sound ray is represented by a cone including the corresponding solid angle; (4) the receiver is a dimensionless point; (5) the outputs obtained in the receiver have a statistical treatment; (6) ray diffusion on rough walls are considered, by means of a calculation based on the Markoff–Chain theory; and (7) obstacles are allowed in the room, and the diffraction over them is considered by a combination of the Helmholtz–Kirchhoff theorem and the Markoff–Chain method. The model was applied to the Lecture Theatre of the High Technical School of Industrial Engineering at Valencia, and the results that were obtained were compared with the measurements taken there. The experimental values were, in 90% of the cases, between those given by the model as probables.
Effects of air conditioning on sound propagation in a large space
Authors: Ueda Yasutaka , Ando Yoichi
Published: October 2005

Sound-pressure level (SPL) fluctuation caused by air conditioners was measured by use of pure tones as the sound source in a gymnasium. When the air conditioner was turned on, the fluctuation of the SPL was more than 2 dB at 2 kHz, 5 dB at 4 kHz, 6 dB at 8 kHz, and 10 dB at 16 kHz. The cumulative density of mean-squared amplitude corresponds well with the gamma distribution. From this statistical analysis, it is considered that the SPL change is caused by the impulse response which is represented by the direct sound (regular) and changing delay time of reflection sound (irregular). The cumulative density of mean-squared amplitude for this model by using the pure tone also indicated the gamma distribution. It is found that the frequency characteristic and the cumulative density of the SPL change have the same tendencies as the method of modulation for the delay time of reflection sound.
A review of nonauditory physiological effects of noise on animals
Authors: Bowles Ann E. , Thompson Shirley J.
Published: October 2005

Early studies of nonauditory physiological effects (1950s–1970s) exposed laboratory animals to unrealistically high levels (continuous levels ≳∼100 dB SPL) without adequate documentation of exposure or appropriate controls. These studies documented genetic and acoustic factors controlling life-threatening audiogenic seizures in rodents. They also reported health effects more usually associated with noxious chemicals, e.g., teratogenicity. Later, carefully controlled studies using somewhat more realistic exposures (∼80–100 dB SPL) contradicted the earlier work. Exposure in this range did cause: increase in blood pressure; change in heart rate and respiration; altered levels of blood factors such as catecholamines and glucocorticoids; increase in arousal as indicated by EEG; and changes in behavior. Recovery to baseline levels was often rapid, and substantial habituation was possible with continued exposure. However, protracted exposure could also result in elevated blood pressure, adrenal hypotrophy or hypertrophy, and immune suppression. Based on these results, health effects will be predicted by exposure level and constancy. At lower levels [Leq(24)<70 dB], studies have consistently failed to find significant nonauditory health effects in laboratory animals and humans. Psychological and sociosituational factors have been an important predictor of noise-induced stress in humans; they are likely to be important in animals as well.
How the temporal sequence of sound is represented in the primary auditory cortex
Authors: Riquimaroux Hiroshi
Published: October 2005

The present study has examined representation of the temporal sequence of sound stimuli in neurons of the primary auditory cortex (AI) in order to investigate how the central auditory system deals with time information. Adult Japanese monkeys (Macaca fuscata) prepared for chronic recordings were used. Stimuli were: noise bursts, tone bursts, and sequentially presented tone bursts. Unit recordings were made from the contralateral AI. During recording sessions, the animal was anesthetized with a mixture of nitrous oxide and oxygen. Post-stimulus-time histograms were analyzed. Results demonstrated that a single neuron in AI often showed totally different temporal firing patterns when different frequencies were presented. Moreover, neurons of this type facilitatively responded to a temporally paired burst of different frequencies with a particular interval (Δt); for a different pair, a different Δt produced a large firing. However, the Δt which evoked a big response did not produce a large excitation when the temporal order was reversed. The interval which elicited the facilitation ranged from ∼50 ms up to ∼200 ms under the various conditions used. These neurons were sensitive to Δt, frequencies, and the order of presentation, implying that they are capable of representing temporally changing sounds like communication sounds.
Call generation strategy in an Old World frog
Authors: Narins Peter M. , Lewis Edwin R.
Published: October 2005

Old World treefrogs in the family Rhacophoridae have complex vocalizations. The vocal repertoire of a population of endemic males, Boophis madagascariensis, was studied in the animals’ natural habitat in Ranomafana National Park in eastern Madagascar. Twenty-eight calls and variations were recorded. This represents the largest call repertoire of any frog reported to date. Playback studies demonstrated the strong tendency for males to respond in kind. Moreover, one sequence of call notes tended to stimulate calling, another inhibited calling, and a third had little effect on the calling behavior of males. Applying permutation tests to 100 calls produced by a single male revealed no predictable pattern to the call production sequence. This implies a call generation scheme for Boophis (and perhaps other Rhacophiorids) that differs fundamentally from New World frogs. [Work supported by NIH and a Guggenheim Fellowship to PMN.]
An analysis of the response of Sooty Tern eggs to sonic boom overpressures
Authors: Ting Carina M. , Garrelick Joel M. , Bowles Ann E.
Published: October 2005

It has been hypothesized that sonic booms caused a mass hatching failure of Sooty Terns on the Dry Tortugas, FL by causing eggs to crack. In this paper the problem is analyzed using two levels of idealization. The first model represents the egg shell as a spherical elastic shell, the embryo as an inertial concentric sphere, and the albumen as an acoustic fluid that completely fills the intervening volume. The substrate is taken to provide a point support for the egg and to double the incident pressure. The second higher fidelity, numerical model accounts for the ‘‘egg shape’’ geometry and allows for an air sac. Here the substrate is modeled as a rigid boundary of infinite extent. In both cases the boom is modeled as an incident, planar N wave. Predictions are compared to each other and with the results of empirical studies previously performed by other investigators. Data from these earlier investigations were obtained with boom-like impulsive noise sources and indicate that the hypothesis that sonic booms crack eggs unlikely. [Work sponsored by Armstrong Lab., WPAFB, U.S. Air Force.]
Acoustical flight path tracking of echolocating bats
Authors: Aubauer Roland
Published: October 2005

Most bats use echolocation for orientation and prey catching. They emit species- and situation-specific ultrasonic sounds and receive from the echoes information about the location, the shape, and the velocity of located targets. It is necessary to study the animals in their habitats under natural conditions in order to understand the foraging and echolocation behavior of bats. The Technical University of Darmstadt, Germany developed a signal-processing system, which makes it possible to analyze bat signals and track a bat’s flight paths in the field. The propagation time differences of bat sounds between several microphones are measured with a new correlation technique. A correlation receiver forms the bats sounds in narrow pulses and allows a time resolution of 2 μs. The signals can be detected and analyzed with a high reliability down to a signal-to-noise ratio of −2 dB. The microphone configuration is optimized for the tracking problem and keeps Doppler ambiguity low. The distance related location error of a flight path tracking is between 0.2% and 2%. The range of the tracking method is between 15 and 50 m.
Acoustic measurement of cardiac function on northern elephant seals
Authors: Burgess William C. , Tyack Peter L. , LeBoeuf Burney J. , Costa Daniel P.
Published: October 2005

A self-contained acoustic recording tag has obtained signatures of heartbeat from both captive and free-ranging northern elephant seals (Mirounga angustirostris). Simultaneous electrocardiogram (ECG) and acoustic signatures obtained from the submerged captive seal confirm that seal heartbeat can be monitored acoustically. Recordings from the free-ranging seal demonstrate shallow-water apneic heart rates of 40 to 55 beats per minute, comparable to past observations with ECG tags. Observation of a sixfold increase in beat amplitude at the surface (110 dB re: 1 μPa) over that at depth (94 dB re: 1 μPa) may reflect increases in stroke volume at the surface. The findings suggest the feasibility of long-term, reliable, quantitative, and noninvasive cardiac monitoring of a variety of free-ranging marine animals using acoustic logging techniques. [Work supported by MBARI and ONR.]
Canine acoustics: Source levels, principal frequencies, and the resulting interaction with the environment
Authors: Scheifele Peter M. , Browning David G.
Published: October 2005

The members of the canine family, wolves, coyotes, foxes, dogs, and to a lesser extent jackals, are one of the best known and widely distributed animal groups. However, compared to bats or dolphins, their acoustic characteristics have received relatively little attention. Although the principal methods of oral communication such as howls, barking, yelping, growls, and whimpers have been identified [Acoustic Behaviour of Animals, edited by R.-G. Busnel (Elsevier, Amsterdam, 1963)], modern analyses of source (and noise) levels have not been reported. This paper presents the results so far to correct this deficiency and from this work it is estimated how changes in environmental noise conditions might impact (and be impacted by) canine communication.
Tooth enamel thickness measurement by ultrasound imaging method
Authors: Yang Zhizong
Published: October 2005

Tooth enamel thickness measurement is of value to archaeologists in classifying hominoid primates. Traditional methods use destructive means of sawing through teeth samples and optically measure enamel thickness. Only in cases where samples were naturally fractured can a direct estimation be made. Experiments were conducted using a pulsed ultrasound technique to measure tooth enamel thickness nondestructively. The experiment used pulsed focused ultrasound transducer and composite scanning techniques to construct images of tooth enamel surface and enamel dentine interface. The ultrasound imaging results clearly showed the caption of tooth enamel interfaces and enabled the calculation of enamel thickness.