bluuebunny/crossref_metadata_2025 huggingface dataset:
Inversion of sound-speed and density profiles in deep ocean sediments
Authors: Chapman N. R. , Levy S. , Stinson K. , Jones I. F. , Prager B. T. , Oldenburg D. W.
Published: October 2005

Wide-angle seismic reflections obtained in a deep ocean environment are analyzed to obtain estimates of the sound-speed profile and density contrasts in the surficial sediment layers. The analysis begins with a new deconvolution technique based on autoregressive modeling, which is used to deconvolve the bubble-pulse signature from the data. Sound-speed profiles are then obtained by inverting the identified arrivals by first treating them as reflection events, and then as refraction events. The first inversion was performed twice, once using a Backus–Gilbert approach (to produce a smooth model) and once using a linear programming method (to produce a blocky model). For the refraction inversion, the Garmany p−τ method was used. Finally, the offset-dependent phase shifts of supercritically reflected arrivals were estimated using the complex Karhunen–Loeve transform. These phase shifts were used with Rayleigh’s equation in a new inversion scheme to obtain density and sound-speed contrasts in the shallow sediments.
Response to ‘‘Comment on ‘Transfer function method of measuring acoustic intensity in a duct system with flow’ ’’ [J. Acoust. Soc. Am. 7
9, 1180 (1986)]
Authors: Blaser Dwight A.
Published: October 2005

D. A. Blaser, co-author of ‘‘Transfer function method of measuring acoustic intensity in a duct system with flow’’ thanks M. S. Vasudevan and F. J. Fahy for their correction of Eq. (35). It should be noted, however, that the typographical error in that equation does not invalidate the numerical results presented in the paper because Eq. (35) was not evaluated explicitly. Instead, the complex acoustic reflection coefficient was evaluated and then used in Eq. (29) to determine the net acoustic intensity in a duct system with flow. [AIP]
Continuous versus gated pedestals and the ‘‘severe departure’’ from Weber’s law
Authors: Carlyon Robert P. , Moore Brian C. J.
Published: October 2005

Thresholds were compared for the detection of 20-ms sinusoidal signals presented with either continuous or gated sinusoidal pedestals of the same frequency (500 or 6500 Hz). Pedestal levels ranged from 35–80 dB SPL. For 500-Hz signals, thresholds were lower in the continuous-pedestal condition than in the gated-pedestal condition, for all pedestal levels above 35 dB SPL. When the pedestal level was 35 dB, thresholds were higher in the continuous-pedestal condition than in the gated-pedestal condition. This was also true at all pedestal levels when bandstop noise centered around the pedestal frequency was added to the pedestal. For 6500-Hz signals, a deterioration in performance at intermediate levels, similar to that reported by Carlyon and Moore [J. Acoust. Soc. Am. 76, 1369–1376 (1984)], was found in the gated-pedestal condition. No such deterioration occurred in the continuous-pedestal condition. However, masking signal onsets and offsets by bursts of bandpass noise produced a midlevel deterioration in the continuous-pedestal condition. This was true when bandstop noise was absent, and when it was gated on and off in each observation interval. When continuous bandstop noise was present, no midlevel deterioration was observed, even when onsets and offsets were masked. The results suggest that in the continuous-pedestal condition subjects may normally maintain performance across level at 6500 Hz by attending to a transient response to signal onsets. Presenting bursts of bandpass noise disrupts the detection of such a response. The absence of a midlevel deterioration when continuous bandstop noise was present may be related to the adaptation to the sinusoidal pedestal that was caused by the bandstop noise.
Reflection and refraction of elastic waves on a plane interface between two generally anisotropic media
Authors: Rokhlin S. I. , Bolland T. K. , Adler Laszlo
Published: October 2005

A unified approach to the study of reflection and refraction of elastic waves in general anisotropic media is presented. Christoffel equations and boundary conditions for both anisotropic media in coordinate systems formed by incident and interface planes, rather than in crystallographic coordinates, are considered. Consideration of wave propagation in an acoustic-axis direction is included in the general algorithm, so results can be obtained both generally and for planes of symmetry, including planes of isotropy. General features of the numerical results are discussed. Energy conversion coefficients are shown to satisfy reciprocity relations which are formulated. It is much more natural to consider intensity–conversion ratios, rather than amplitude–conversion ratios, showing the important role of ray (rather than wave-vector) directions in describing phenomena such as grazing angles. In particular, it is shown that the incident wave vector for grazing incidence may be greater or less than 90°: The domain of incident wave-vector angles can actually split into disjoint pieces. The reflection coefficient at grazing incidence is shown to be unity, as in the isotropic case. Critical-angle phenomena are described naturally by this approach.
An analysis of nonlinear resonance in contoured-quartz crystal resonators
Authors: Tiersten H. F. , Stevens D. S.
Published: October 2005

Electroelastic equations containing terms up to cubic in the small mechanical displacement field, but no higher than linear in the electric variables, are applied in the analysis of nonlinear resonance in doubly rotated contoured-quartz resonators and all terms present in the general anisotropic case are included. Since the modes of motion in contoured-quartz resonators are essentially thickness modes varying slowly along the plate, only the thickness dependence of the elastic nonlinearities are retained in the equations, as in earlier work. The linear portions of the equations are the same as those that have recently been derived and employed in the analysis of doubly rotated contoured-quartz resonators. The steady-state solutions are obtained by means of an asymptotic iterative procedure and an expansion in the linear eigensolutions while retaining the nonlinear correction to the eigensolution that has a resonant frequency in the vicinity of the driving frequency. The slow variations in the mode along the plate are included in the nonlinear correction by averaging over the plate. Lumped parameter representations of the solutions, which are valid in the vicinity of a resonance and relate the amplitude of the mode nonlinearly to the voltage across the electrodes, are obtained. In each instance the expression for the current through the crystal is determined, the external circuitry is incorporated in the description and an equation relating the mode amplitude nonlinearly to the driving voltage and other circuit parameters is obtained. The analysis holds for the fundamental and odd harmonic overtones. Nonlinear resonance curves are calculated for AT-cut quartz using the known nonlinear coefficients. In particular, it is shown that the order of the harmonic has a more significant influence on the shift in resonant frequency from the linear value than the current through the crystal. An equation relating the change in resonant frequency resulting from the nonlinearity to the current through the crystal, independent of the external circuitry, is derived. This latter equation is employed in the evaluation of the coefficient of nonlinear resonance for SC-cut quartz from measurements of the shift in resonant frequency with current level in contoured resonators.
High-frequency bottom backscatter measurements in shallow water
Authors: Jackson Darrell R. , Baird Andrew M. , Crisp John J. , Thomson Patricia A. G.
Published: October 2005

Bottom backscatter measurements have been made at six shallow-water sites over the frequency range 20–85 kHz for bottom types including silt, sand, and gravel. Bottom samples were taken at all experimental sites, and some sites are well characterized in terms of seabed acoustic parameters and roughness. A slight frequency dependence was observed, and scattering strength was generally found to decrease as grazing angle decreased. Backscatter measurements in four azimuthal directions showed no measurable anisotropy for grazing angles between 10° and 40°. Spatial variability of backscatter strength was measured along two tracks approximately 35 and 75 km long.
Reflection and transmission of an obliquely incident wave by an array of spherical cavities
Authors: Achenbach J. D. , Kitahara M.
Published: October 2005

A plane wave is incident on a doubly periodic array of spherical cavities in an elastic solid. The cavities are of equal radius d, and their centers are located in a single plane, the x1x2 plane, at positions x1=ma, x2=nb. The propagation vector of a plane, time-harmonic, incident longitudinal wave is located in the x1x3 plane. The scattering problem is formulated rigorously by taking advantage of the geometrical periodicity. The reflected and transmitted longitudinal and transverse wave motions may be expressed as superpositions of an infinite number of wave modes, each with its own cutoff frequency. Reflection and transmission coefficients have been defined as integrals over a single cavity in terms of the displacement components and auxiliary surface traction terms on the surface of the cavity. The system of singular integral equations for the displacement components has been solved numerically by the boundary integral equation method. Curves show the reflection and transmission coefficients for the reflected and transmitted longitudinal and transverse waves as functions of the frequency.
Scattered wave inversion for arbitrary receiver geometry
Authors: Porter Robert P.
Published: October 2005

By combining images from backpropagated scattered waves from successive plane-wave illuminated scatterers, we are able to reconstruct a low-pass filtered version of the three-dimensional scattering function of a weak scatterer. Imaging or, equivalently, backpropagation corrects for the spherically diverging scattered field permitting sparse sampling on the recording surface and making coherent wave inversion more practical. As in conventional tomography, true reconstruction requires a filtering operation on the scattered field recorded on a planar hologram or other recording medium. For holograms of arbitrary shape, a postfiltering operation is needed to produce a low-pass replica of the object. This work draws heavily on the theory of generalized holography developed for holograms of arbitrary surface shape.
Spurious resonances in adaptations of elastic layer model to simulate liquid layers
Authors: George Jacob
Published: October 2005

When computer programs based on an elastic layer model [e.g., Folds and Loggins, J. Acoust. Soc. Am. 62, 1102 (1977)] are used to simulate liquid layers, spurious resonances in the transmission coefficient appear as a function of frequency. It is shown that they are not caused by numerical precision limitations in the computer, but are inherent in the model. In the computer representation of the elastic layer model, the limit of the Lamé constant μ→0 is approximated by assigning a very small value for μ. With such a choice, spurious resonances appear when the transmission coefficient is plotted as a function of frequency. This is also proven analytically, and graphs are used to illustrate the mechanism of typical resonances. For frequencies away from the spurious resonances, the model does yield the correct liquid layer results.
Discrimination and response bias for CV syllables differing in voice onset time among children and adults
Authors: Elliott Lois L.
Published: October 2005

A previous experiment demonstrated age-related differences in voice-onset-time (VOT) discrimination when an adaptive procedure was used and trials were concentrated among pairs of stimuli that were discriminated 50% of the time. The major purpose of this experiment was to determine whether the same types of age effects would be replicated for new groups of subjects and a different task in which all stimuli were presented equal numbers of times. An eight-item, five-formant consonant–vowel (CV) continuum in which VOT ranged from 0–35 ms was used. The same–different task presented all possible pairs of CV syllables in which VOT differed by 10 and 20 ms and an equal number of catch trials that contained identical CVs. Results showed that children displayed poorer discrimination than adults for CV pairs differing by both time intervals. Adults displayed a somewhat greater tendency to respond ‘‘same’’ than children. The outcomes supported results of the previous study and were interpreted as representing true age-related differences in VOT discrimination.
Beating motion of a damped mechanical oscillator
Authors: Cunniff Patrick F. , O’Hara George J.
Published: October 2005

The beating motion of a damped mechanical oscillator is examined for three different forcing functions that produce expanding beating, decaying beating, and steady beating, respectively. In the case of decaying beating, both the frequencies where the peaks occur in the shock and Fourier spectra derived from the beating signal are predicted, as well as the damping factor associated with the mathematical form of the beating motion.
On the role of spectral transition for speech perception
Authors: Furui Sadaoki
Published: October 2005

This paper examines the relationship between dynamic spectral features and the identification of Japanese syllables modified by initial and/or final truncation. The experiments confirm several main points. ‘‘Perceptual critical points,’’ where the percent correct identification of the truncated syllable as a function of the truncation position changes abruptly, are related to maximum spectral transition positions. A speech wave of approximately 10 ms in duration that includes the maximum spectral transition position bears the most important information for consonant and syllable perception. Consonant and vowel identification scores simultaneously change as a function of the truncation position in the short period, including the 10-ms period for final truncation. This suggests that crucial information for both vowel and consonant identification is contained across the same initial part of each syllable. The spectral transition is more crucial than unvoiced and buzz bar periods for consonant (syllable) perception, although the latter features are of some perceptual importance. Also, vowel nuclei are not necessary for either vowel or syllable perception.
Axisymmetric vibration of a piezoelectric solid cylinder guided by a thin film
Authors: Paul H. S. , Venkatesan M.
Published: October 2005

The exact frequency equation for the axisymmetric vibration of a piezoelectric cylinder guided by a thin film of (6 mm) or (∞ m) class is obtained. The surface of the cylinder is coated with a perfectly conducting material. The same problem is analyzed by an asymptotic method. The numerical results obtained in the exact method are compared with the solutions of the asymptotic method for 0<ε≤0.1 (where ε is the dimensionless wavenumber). The dispersion curve has been presented graphically and it is compared with the dispersion curve obtained for the vibration of a piezoelectric solid cylinder without a coating.
Solutions of elastodynamic slab problems using a new orthogonality condition
Authors: Folk Robert , Herczynski Andrzej
Published: October 2005

An orthogonality condition developed and used by R. Folk [Ph. D. thesis, Lehigh University (1958)] to solve elastodynamic problems for slabs is generalized so that it applies to the eigenfunctions of a class of nonself-adjoint operators and so that these eigenfunctions are also the dual-space functions. This orthogonality condition is used to determine the coefficients in a sum of eigenfunctions satisfying any mixed end conditions on a semi-infinite elastic slab. To test the practicality of this general solution, the time-varying stress is evaluated for a slab that is subjected to a step-function normal stress on its end. Details are given of how the integrals and the sum occurring in the answer are evaluated.
Space variances in the mean-square pressure at the boundaries of a rectangular reverberation room
Authors: Tohyama Mikio , Suzuki Akira
Published: October 2005

It was found that it was possible to reduce the number of samples needed for power measurements by sampling at the boundaries in a reverberation room. The space variances in the mean-square pressure of oblique wave fields in a rectangular reverberation room were calculated. The sound source was assumed to be a narrow-band noise source. Space variances throughout the room σ2A, on the floor σ2B, on the edge σ2C, and at the corner σ2G were compared with each other numerically. The numerical results confirmed that the relation σ2G <σ2C <σ2B <σ2A holds well. Particularly, in a rectangular reverberation room, under the condition that the receiver position is fixed at the corner of the room (corner method), the number of samples reduces to (1)/(2) – (1)/(3) the number of samples needed under the condition that both receiver positions and source positions are changed throughout the room. Some experimental results regarding the power measurements by the corner method are also shown. The experimental results confirmed the suitable estimation of the power for a noise source at low frequencies.
Nonlinear response in evaluating the subjective diffuseness of sound fields
Authors: Ando Yoichi , Kurihara Yoshitaka
Published: October 2005

Tests were conducted to determine which horizontal reflection angles are most effective in stimulating subjective diffuseness for a listener in a room. Paired comparison tests were carried out where subjects were asked to judge in which of two sound fields they perceived more diffuseness. Results show that the most effective horizontal angle depends on the frequency of the one-third-octave-band noise, as is indicated by the interaural cross correlation. The remarkable finding in this investigation is that the scale value of subjective diffuseness may be formulated in terms of the (3)/(2) power of the magnitude of interaural cross correlation (IACC) and that the scale value does not vary with the frequency of the bandpass noise source.
Experimental study of a slow-waveguide barrier on finite impedance ground
Authors: Nicolas J. , Daigle G. A.
Published: October 2005

A slow-waveguide filter consisting of an open network of rigid strips is used to modify a conventional noise barrier. The acoustical performance of the resulting device relies on the interference between the field diffracted by the barrier edge and the field propagating through the waveguide. The possibilities of enhancing low-frequency noise reduction with this device is studied experimentally. In addition, limitations in the existing waveguide model are removed and the theory is extended to allow for reflections due to the presence of the ground. Both theory and experiments show that, at frequencies where significant destructive interference occurs between the diffracted field and the field transmitted through the waveguide, there is an enhanced noise reduction. However, at adjacent frequencies there is constructive interference which can degrade the performance of the barrier.
Closed-form solutions for rigorous ray tracing
Authors: Floyd Edward R.
Published: October 2005

Closed-form solutions and expressions for rigorous ray tracing are presented for the effective sound velocity profile, the generating function, the equations of motion, and the initial conditions. These closed-form solutions may be expressed in terms of the closed-form solutions of the corresponding Helmholtz equation. Even if the closed-form solutions for the corresponding Helmholtz equation are unknown, we may still process rigorous ray tracing in terms of the symbolic solutions of the Helmholtz equation. Comparisons are made to both normal modes and classical ray tracing. An Ermakov invariant for rigorous ray tracing is developed and evaluated with closed-form solutions. A Green’s function that is couched in terms of closed-form rigorous-ray-tracing solutions is developed for acoustic sources.
A computer model for simulating reflected ultrasound signals
Authors: Kuc Roman , Miwa Hirohide
Published: October 2005

This letter describes a model for simulating an ultrasound signal reflected from a medium composed of randomly distributed scatterers, as typified by soft biological tissue, such as liver. The model is specified in terms of the effective transducer beam radius B and the mean scatterer spacing S. The novel feature of the model is that the transducer field is partitioned by packing cylinders, called microbeams, into concentric annular regions that lie parallel to the transducer axis. The radii of the microbeams and the annuli are related to S. An independent reflector sequence is generated for each microbeam, the microbeam sequences in each annulus are summed and convolved with the impulse response of a point reflector. The reflected waveform sequence is then generated by summing the annular contributions and convolving with a band-limited pulse waveform. Simulated signals were generated for different values of B and S and compared with actual signals reflected from two in vivo livers and a tissue-equivalent phantom. Estimates of the kurtosis for the simulated signals indicate the range of signals that can be generated by varying the values for S and B.
Pitch and rhythm paradoxes: Comments on ‘‘Auditory paradox based on fractal waveform’’ [J. Acoust. Soc. Am. 7
9, 186–189 (1986)]
Authors: Risset Jean-Claude
Published: October 2005

Schroeder [J. Acoust. Soc. Am. 79, 186–189 (1986)] describes the paradox of acoustic waveforms that sound lower when reproduced at higher speeds. The author has also demonstrated this paradox [J. C. Risset, J. Acoust. Soc. Am. 46, 88 (A) (1969); see also Seventh ICA, Budapest, S10, 613–616 (1971)]; in addition he has recently synthesized a rhythmic analog of the paradox, namely rhythmical sequences that can sound slower when reproduced at higher speeds.
Acoustics of ear canal measurement of eardrum SPL in simulators
Authors: Gilman Samuel , Dirks Donald D.
Published: October 2005

The effect of standing waves on the ear canal measurement of eardrum sound pressure level (SPL) was determined by both calculation and measurement. Transmission line calculations of the standing wave were made using the dimensions of the ANSI S3.25-1979 ear simulator and three different eardrum impedances. Standing wave curves have been obtained for the standard eardrum impedance at 1-kHz intervals in the range of 1–8 kHz. The changes in standing wave position due to each of the three eardrum impedances and their effects on ear canal measurements of SPL were computed for each of the eardrum impedances. Ear canal SPL measurements conducted on simulators modified to correspond to the eardrum impedances used in the calculations were compared to the computed values. Differences between eardrum SPLs and those measured at different locations in the ear canal approached a standing wave ratio (SWR) of 10–12 dB as the position of the measuring probe approached the standing wave minimum at each frequency. These maximum differences compared favorably with data developed by other investigators from real ears. Differences due to the eardrum impedance were found to be significant only in the frequency region of 2–5 kHz. Calibration of probes in a standard or modified ANSI simulator at the same distance from the eardrum as in the real ear reduces the eardrum SPL measurement errors to those resulting from differences in eardrum impedance.
The effect of bandwidth on the performance of a postbeamformer interference canceller
Authors: Godara Lal C. , Cantoni Antonio
Published: October 2005

A postbeamformer interference canceller, PIC, processes the signals derived from an antenna array by forming two beams using fixed beamforming weights. The weighted output of one beam, referred to as the interference beam, is subtracted from the other beam referred to as the target beam. This paper analyzes the performance of PIC in the presence of narrow-band directional interference by deriving the analytical expressions for the output signal power, the output interference power, and the output signal to interference ratio, and presents the results of a computer study showing how the performance of PIC varies as a function of bandwidth of the directional sources.
A design for a general digital filter for state estimation of an arbitrary stochastic sound system
Authors: Ohta Mitsuo , Uchino Eiji
Published: October 2005

This article describes a new attempt at the design of a general digital filter for the state estimation of a nonstationary nonlinear stochastic sound system. A recursive algorithm for estimating the higher-order statistics of arbitrary-function type, mean, and variance is obtained by introducing a new expansion form of Bayes’ theorem. Further, the state probability density function (PDF) can also be estimated in a unified form of orthogonal or nonorthogonal series expansions by using these estimates. This method is widely applicable for cases where the random-noise fluctuation is non-Gaussian. The estimation algorithm proposed in this article agrees completely with a well-known Kalman filtering theory [J. Basic Eng. 82, 35–45 (1960); Kalman and Buchy, J. Basic Eng. 83, 95–108 (1961)], as a simplified special case when the stochastic system is of linear type with Gaussian random excitation. The validity and effectiveness of the proposed theory were confirmed experimentally by applying it to actually observed room acoustic data and road-traffic noise data.
Echolocation transmitting beam of the Atlantic bottlenose dolphin
Authors: Au Whitlow W. L. , Moore Patrick W. B. , Pawloski Deborah
Published: October 2005

The transmitting beam patterns of echolocation signals emitted by an Atlantic bottlenose dolphin Tursiops truncatus were measured in the vertical and horizontal planes with an array of seven hydrophones. Particular emphasis was placed on accurately verifying the animal’s position on a bite-plate/tail-rest stationing device using underwater video monitoring equipment. The major axis of the vertical beam was directed at an angle of 5° above the plane defined by the animal’s lips. This angle was 15° lower than previously measured. The vertical beam measurements indicate that the major axis of the transmitting beam is aligned with the major axis of the receiving beam. The horizontal beam was directed forward. The directivity index of 26.5 dB calculated from the beam pattern measured in both planes agreed well with previous calculation of 25.4 dB.
Elderly listeners’ estimates of vocal age in adult females
Authors: Linville Sue Ellen , Korabic Edward W.
Published: October 2005

The purpose of this study was to provide data on the ability of elderly listeners to estimate the age group of women (25–35, 45–55, 70–80) from phonated and whispered vowel productions. Further, comparisons were made between the performance of these elderly listeners and results for young listeners reported previously [S. E. Linville and H. Fisher, J. Acoust. Soc. Am. 78, 40–48 (1985)]. Tape recordings of whispered and normally phonated /æ/ vowels were played to 23 elderly women for relative age judgments. Results suggest that elderly women are not as accurate as young women in estimating age from sustained vowel productions, although the two listener groups tend to categorize individual speakers similarly. Further, it appears that listener age is a factor in acoustic cues used in making age judgments.
A central spectrum theory of binaural processing. Evidence from dichotic pitch
Authors: Raatgever Johan , Bilsen Frans A.
Published: October 2005

A theory is presented that describes the binaural processing of interaural time or phase differences. It is an elaboration of the central spectrum concept for the explanation of dichotic pitch phenomena [F. A. Bilsen, ‘‘Pitch of noise signals: Evidence for a ‘central spectrum’,’’ J. Acoust. Soc. Am. 61, 150–161 (1977)]. The generation is postulated for central activity patterns (CAP) due to binaural interaction. From these CAPs the central processor selects specific spectral information that constitutes the information for lateralization, dichotic pitch, binaural masking, etc. Here, a strategy is assumed to be based on central spectra (CS) rather than on interaural cross correlation. For the calculation of the central activity patterns a number of assumptions have been introduced. The peripheral filters are supposed to be infinitesimally narrow. The analog filter outputs from corresponding filters at both ears are thought to interact by means of a linear delay-and-add mechanism. The squared output (power) of such a binaural (addition) network constitutes the CAP. The theory has been tested with lateralization and BMLD measurements using dichotic stimulus configurations characteristic of the perception of dichotic pitch. The predictions of the model concerning the pitch and the lateralization of the pitch images as well as the BMLD patterns for this kind of stimuli are confirmed.
A central spectrum theory of binaural processing. The binaural edge pitch revisited
Authors: Frijns Johan H. M. , Raatgever Johan , Bilsen Frans A.
Published: October 2005

Recently, Klein and Hartmann [J. Acoust. Soc. Am. 70, 51–61 (1981)] investigated a new dichotic pitch, called the binaural edge pitch (BEP). They used computer-generated periodic noise signals to generate BEP. In the study presented here, the BEP is investigated in order to evaluate the predictions of the central spectrum theory with regard to this stimulus. Pitch-matching experiments using a nonperiodic BEP stimulus, produced by means of a modulation technique, led to the conclusion that the strongest pitch sensation in the BEP has the character of a weak fluctuating pure tones in noise, which corresponds to a frequency, equal or almost equal to the frequency of the phase transition. This result fits in with the predictions of the central spectrum theory, which, for instance, does not need the assumption of central lateral inhibition for explaining this pitch. Furthermore, it is shown that this theory can also predict the results obtained in lateralization measurements and BMLD measurements using BEP stimuli as well as related stimuli. The results are compared with the data obtained by Klein and Hartmann.
Effect of signal phase and masker separation on two-tone masking
Authors: Hanna Thomas E.
Published: October 2005

The detectability of a sinusoid masked by two sinusoids was studied as a function of signal phase and the frequency separation between the two maskers. The signal frequency fs was equal to the arithmetic mean of the two masker frequencies, fl and fh, where fl0.4, no consistent effects of signal phase were observed. For r<0.4, an effect of signal phase was evident at both signal frequencies. However, the effect of signal phase was different for the two regions 0.03<r<0.4 and r<0.03. For moderate masker separations, 0.03<r<0.4, masked thresholds were lowest at phases of 0° and 180° and highest at phases of 90° and 270°. For small masker separations, r<0.03, masked threshold was highest at 0° and the effect of signal phase depended on signal frequency. The different form of the phase effect for these three regions is discussed in terms of the use of different cues, arising from temporal resolution, spectral filtering, combination tones, and envelope spectra.
Thresholds for hearing mistuned partials as separate tones in harmonic complexes
Authors: Moore Brian C. J. , Glasberg Brian R. , Peters Robert W.
Published: October 2005

When a low harmonic in a harmonic complex tone is mistuned from its harmonic value by a sufficient amount it is heard as a separate tone, standing out from the complex as a whole. This experiment estimated the degree of mistuning required for this phenomenon to occur, for complex tones with 10 or 12 equal-amplitude components (60 dB SPL per component). On each trial the subject was presented with a complex tone which either had all its partials at harmonic frequencies or had one partial mistuned from its harmonic frequency. The subject had to indicate whether he heard a single complex tone with one pitch or a complex tone plus a pure tone which did not ‘‘belong’’ to the complex. An adaptive procedure was used to track the degree of mistuning required to achieve a d′ value of 1. Threshold was determined for each ot the first six harmonics of each complex tone. In one set of conditions stimulus duration was held constant at 410 ms, and the fundamental frequency was either 100, 200, or 400 Hz. For most conditions the thresholds fell between 1% and 3% of the harmonic frequency, depending on the subject. However, thresholds tended to be greater for the first two harmonics of the 100-Hz fundamental and, for some subjects, thresholds increased for the fifth and sixth harmonics. In a second set of conditions fundamental frequency was held constant at 200 Hz, and the duration was either 50, 110, 410, or 1610 ms. Thresholds increased by a factor of 3–5 as duration was decreased from 1610 ms to 50 ms. The results are discussed in terms of a hypothetical harmonic sieve and mechanisms for the formation of perceptual streams.
Effects of bandwidth and stimulus type on most comfortable loudness levels of hearing-impaired listeners
Authors: Byrne Denis
Published: October 2005

Measurements were made of the effects of stimulus bandwidth and type (speech bands versus pure tones) on interfrequency differences at the most comfortable loudness level (MCL). The MCLs were measured for speech bands of three bandwidths (1/3 octave, 1 octave, and 1 2/3 octaves) at three frequencies (0.4 kHz, 1.25 kHz, and 3.15 kHz) for 11 sensorineurally hearing-impaired subjects (14 test ears). The MCLs were also measured with pulsed pure tones. It was found that bandwidth and stimulus type both had significant effects on interfrequency differences in MCLs. Also, the mean speech band MCLs were significantly higher than the mean pure-tone MCLs. A subsidiary experiment suggested that, when bands of speech from different frequency regions are all presented at MCL, they will be approximately, but not precisely, equal in loudness. The findings have implications for hearing aid selection procedures because most aim to amplify all frequency bands of speech to MCL, or equal loudness at a comfortable level. The use of different types or bandwidths of test stimuli would result in substantially different frequency response prescriptions in some cases.
The effects of skin temperature on the psychophysical responses to vibration on glabrous and hairy skin
Authors: Verrillo Ronald T. , Bolanowski Stanley J.
Published: October 2005

Psychophysical detection thresholds for vibration were measured at the thenar eminence and volar forearm using a 0.008-cm2 (1.0-mm-diam) contactor. Measurements were made at 14 sinusoidal frequencies between 12 and 500 Hz at six skin temperatures between 15° and 40 °C. The results are consistent with the hypothesis that three functionally discrete non-Pacinian afferent systems mediate vibrotactile responses. It was possible to identify the response characteristic of the rapidly adapting (Meissner) system, but it was not possible to isolate the responses of two slowly adapting (SAI, SAII) systems.
Transfer function technique for impedance and absorption measurements in an impedance tube using a single microphone
Authors: Chu W. T.
Published: October 2005

Using a periodic pseudorandom sequence as the noise source, it is possible to implement the two-microphone transfer function technique for impedance and absorption measurement in an impedance tube with a single microphone, thereby eliminating the elaborate calibrating procedure and any error associated with phase-mismatching. Results obtained by the proposed procedure compared well with those obtained by the standard standing-wave-ratio method.
Study of adhesive bonds using low-frequency obliquely incident ultrasonic waves
Authors: Rokhlin S. I. , Marom D.
Published: October 2005

The effect of the difference between slip and rigid boundary conditions on the value of the ultrasonic wave reflection coefficient from an interface is used to study properties of adhesively bonded interfaces. It is shown that changes of the amplitude of the reflected ultrasonic wave during adhesive curing occurred simultaneously with changes of the ultrasonic velocity in the adhesive. The method can be used for cure monitoring of thin adhesive layers and predicting the joint strength. The sensitivity of the method to evaluate interface properties is shown to be higher for thinner adhesive interface films.
Measurement of fish target strength with a split-beam echo sounder
Authors: Foote Kenneth G. , Aglen Asgeir , Nakken Odd
Published: October 2005

Data derived with a 38-kHz split-beam echo sounder have been analyzed to yield target strengths suitable for use with echo integrators. This has required compensation for both thresholding and saturation, since these operations can significantly bias data intended for use with systems, such as echo integrators, whose dynamic ranges are much larger. A nonparametric statistical method is introduced for this purpose. Pure-species acoustic data are extracted in several two-species cases by a method for separating superimposed frequency distributions. Mean in situ target strengths are presented for cod, saithe, Norway pout, herring, redfish, and greater silver smelt. For com- parison with other data, these are expressed through the standard equation ∼(TS) =20 log l +b, where ∼(TS) is the mean target strength in decibels, and l is the fish length in centimeters. For gadoids of lengths from 10 to over 105 cm, b=−67.5 dB. For herring of lengths from 24 to 34 cm, b=−72.1 dB. The often-ignored problem of obtaining unambiguous biological data by trawl sampling is discussed.
A multibounce, single-scatter ray theoretic model
Authors: Tolstoy A. , Berman D. H. , Wright E. B. , Baer R. N.
Published: October 2005

This study describes theoretical predictions for deep-water bistatic reverberation from a bossed surface (with boss depth a) overlying an upwardly refracting, linear, sound-speed environment. The major result of this work is that over a large range of ka (wavenumber k, 0.1≤ka≤10) the strongest scattered field is produced by the rough surface directly above the submerged source and above the receiver. Our model considers both the azimuthal and vertical redistribution of scattered energy caused by randomly distributed hard or soft bosses situated on a hard or soft boundary. The model allows one nonspecular surface scattering per path (connecting the source with the receiver) coupled with any number of specular interactions (bounces), each of which suffers losses due to scattering into nonspecular directions, i.e., consistent with conservation of energy. The propagation model is based on ray theory while the scattering model uses Twersky’s scattering cross section for hard or soft planar surfaces roughened by hard or soft, hemispherical bosses, and we note when such differences become important. The model calculates intensity at a point as a function of distance and direction from the scattering region. This paper represents a first step toward development of an under-ice reverberation model.
Acoustically induced seismic waves
Authors: Sabatier James M. , Bass Henry E. , Bolen Lee N. , Attenborough Keith
Published: October 2005

When an airborne acoustic wave is incident at the ground surface, energy is coupled into the ground as seismic motion. In a previous publication [Sabatier et al., J. Acoust. Soc. Am. 78, 1345–1352 (1986)] the ground surface was modeled as an air-filled poroelastic layer overlying a semi-infinite, nonporous elastic substrate. In this work, the model is extended to include calculations of the normal seismic transfer function (ratio of the normal soil particle velocity at a depth d to the acoustic pressure at the surface). Measurements of the seismic transfer function for three sites are considered and compared to the predicted values. Generally good agreement between theory and experiment is achieved by best fits assuming the soil or seismic attenuation. This is accomplished by specifying the ratio of the imaginary to real part of the measured seismic p- and s-wave speeds. The seismic transfer functions quite typically exhibit minima and maxima which are associated with the seismic layering of the ground surface. Typical layer depths are 1–2 m. An analytical expression predicting the location of these maxima is offered based on hard substrate and the experimental and theoretical comparisons are reasonable.
Ray paths near the ground in a realistic thermally stratified atmosphere
Authors: Van Moorhem W. K. , Ma Yiping , Brown James M.
Published: October 2005

Analytic forms for the acoustic rays in a realistic model of a thermally stratified atmosphere are presented. The present model for the temperature of the atmosphere as a function of height above the ground is in much closer agreement with observed temperature profiles, within a few meters of the ground, than the commonly used linear sound speed or approximate linear temperature profiles. Although the form of the rays is more complicated than in the simple case they are still easily programmable on a calculator or small computer and their behavior also appears to be much more realistic. Both the cases of lapse and inversion temperature profiles are considered.
Two-ear correlation in the statistical sound fields of rooms
Authors: Lindevald I. M. , Benade A. H.
Published: October 2005

The normalized correlation function R( f ) connecting the signals at the left and right ears was measured in a reverberant room as a function of frequency. Head diffraction effects are made evident by comparing these data to the correlation function predicted and observed for two microphones separated by a headwidth (15 cm) of space and moving in the same room. In contrast to the familiar two-mike sinc(δ) correlation (δ=kd), head diffraction gives a two-ear correlation function which is well described by sinc(αδ)/[1+(βδ)4]1/2, where α=2.2 and β=0.5. The dominant effect of head diffraction is to lower  fD, the decoupling frequency [first zero of R( f )] to 500 Hz, about half the no-head value. The denominator in the fitted correlation function represents the near total independence of the signals at the two ears above  fD. Thus with head diffraction the variance in a paired-mike room averaged pressure amplitude estimate at around 500 Hz is already as small as that obtained sans head only at frequencies above 1200 Hz.
Scattering of sound waves by a periodic array of slotted waveguides
Authors: Mongeau L. , Amram M. , Rousselet J.
Published: October 2005

The problem of scattering of plane acoustic waves obliquely incident upon a barrier consisting of superposed rectangular slotted waveguides is treated by taking a waveguide approach. The wave equation is solved for each interior region, bounded by parallel walls, and for the half-spaces on both sides of the scattering arrangement. The use of boundary conditions then leads to two infinite systems of algebraic equations, the solution of which generates the complex transmission and reflection coefficients. The scattering effects of comblike structures show sharp variations over the frequency spectrum. They also vary strongly at certain particular frequencies with the angle of incidence of the incoming wave. Two geometries of slotted waveguides are studied and their behavior, regarding the amplitude and phase of the transmitted sound, is compared with that of a simple grating of rectangular bars having similar dimensions. Theoretical results compare favorably with experimental values which are presented in another article forming the second part of this study.
A rate gyro based on acoustic mode coupling
Authors: Bruneau Michel , Garing Christian , Leblond Henri
Published: October 2005

This paper describes the use of inertial effects from rotation of an acoustic field to determine angular velocities, with a gyroscopic instrument as a goal. A resonant acoustic cavity is used to increase the acoustic particle velocity and the associated Coriolis force; a ‘‘gyroscopic coupling’’ of two perpendicular axial modes occurs between the driven mode and that produced by rotation of the cavity. The ‘‘Coriolis acoustic pressure source’’ is distributed only inside the boundary layers because viscous and thermal phenomena are involved in the process. Calculations clearly reveal that one should be able to reach a sensitivity better than 0.01°/s (the angular velocity of the minute hand of a watch is ten times faster). A rectangular cavity filled up with air and tuned to the first axial mode (0,0,1) already allows the measurement of angular velocities in the range from 0.1°/s–100°/s with uncertainties typically less than 0.1°/s and very good linearity.
Equal-energy streamlines
Authors: Waterhouse R. V. , Feit D.
Published: October 2005

Energy streamlines show the direction of energy flow in a sound field: The intensity vector at any point is tangential to the streamline passing through that point. In earlier work, a procedure for computing energy streamlines was described [J. Acoust. Soc. Am. 78, 758–762 (1985)], but it did not give equally spaced streamlines. The latter have certain advantages, and a method for computing them is presented here. It is shown that in sound fields which vary in only two space dimensions, a scalar stream function exists, the contours of which are the energy streamlines. The stream function is obtained from the intensity function (or values) by an integration procedure. Examples of equally spaced streamlines are given for the point-driven, fluid-loaded plate, and for the baffled rigid piston.
An articulation index based procedure for predicting the speech recognition performance of hearing-impaired individuals
Authors: Pavlovic Chaslav V. , Studebaker Gerald A. , Sherbecoe Robert L.
Published: October 2005

An articulation index calculation procedure developed for use with individual normal-hearing listeners [C. Pavlovic and G. Studebaker, J. Acoust. Soc. Am. 75, 1606–1612 (1984)] was modified to account for the deterioration in suprathreshold speech processing produced by sensorineural hearing impairment. Data from four normal-hearing and four hearing-impaired subjects were used to relate the loss in hearing sensitivity to the deterioration in speech processing in quiet and in noise. The new procedure only requires hearing threshold measurements and consists of the following two modifications of the original AI procedure of Pavlovic and Studebaker (1984): (1) The speech and noise spectrum densities are integrated over bandwidths which are, when expressed in decibels, larger than the critical bandwidths by 10% of the hearing loss. This is in contrast to the unmodified procedure where integration is performed over critical bandwidths. (2) The contribution of each frequency to the AI is the product of its contribution in the unmodified AI procedure and a ‘‘speech desensitization factor.’’ The desensitization factor is specified as a function of the hearing loss. The predictive accuracies of both the unmodified and the modified calculation procedures were assessed by comparing the expected and observed speech recognition scores of four hearing-impaired subjects under various conditions of speech filtering and noise masking. The modified procedure appears accurate for general applications. In contrast, the unmodified procedure appears accurate only for applications where results obtained under various conditions on a single listener are compared to each other.