bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrotactile thresholds for detection of sinusoidal vibration as a function of stimulus duration measured in the presence of vibratory background noise
Authors: Gescheider G. A. , Hoffman Kathleen , Travis Michael , Bolanowski Stanley J. , Verrillo Ronald T.
Published: October 2005

Thresholds for the detection of sinusoidal vibration were measured for stimuli ranging in duration from 15 to 1000 ms. The test stimuli were 250-Hz bursts of vibration with 10-ms rise-fall times applied through either a 3.0 or 0.01 cm2 contactor to the thenar eminence of the right hand. Thresholds were measured in the presence of and in the absence of narrow-band noise with frequencies centered around that of the test stimuli. Temporal summation, as indicated by a decrease in thresholds as stimulus duration increases, was observed at all intensities of the noise masker. This was true whether the stimulus was delivered through a large contactor designed to stimulate the Pacinian channel or through the small contactor designed to stimulate non-Pacinian systems. On the other hand, when stimuli were detected in the presence of sinusoidal maskers, the amount of temporal summation depended on the intensity of the masker in a way predictable from the hypothesis that temporal summation can occur in the Pacinian, but not in one of the non-Pacinian channels.
Frequency selectivity and pitch discrimination in young and elderly subjects with cochlear hearing loss
Authors: Peters Robert , Moore Brian C. J.
Published: October 2005

Pure and complex tone pitch discrimination data were obtained for two groups of hearing-impaired subjects, young and elderly, and for normally hearing subjects. Auditory filter shapes were also estimated for center frequencies of 100, 200, 400, and 800 Hz using a modified notched-noise method [B. J. Glasberg and B. C. J. Moore, Hear. Res. 47, 103–138 (1990)]. Frequency DLs for pulsed tones were measured for frequencies from 50–4000 Hz. DLs for the fundamental frequency (F0) of complex tones were measured for F0s of 50, 100, 200, and 400 Hz, for complexes containing harmonics 1–12, 6–12, 4–12, and 1–5. The components were added in either cosine phase or in alternating sine-cosine phase. Auditory filters for the young and elderly impaired subjects were similar; both groups had broader filters than the normal subjects. Complex tone DLs were larger for the impaired subjects. Complex tone DLs were especially large for the tones with harmonics 1–5 and 1–12 at F0s of 50 and 100 Hz. These DLs were reduced (i.e., performances improved) when the lower harmonics were removed. Complex tone DLs were affected by the relative phases of the components for some but not all of the hearing-impaired subjects. The implications of the results for pitch theories will be discussed. [Research supported by the Andrus Foundation.]
Multimode database and its preliminary results
Authors: Wallace Karen , Horna Josephine , Monzen Yukiko , Umeda Noriko
Published: October 2005

Data from four speaking modes—word-list reading, text reading, conversation, and reading of sentences occurring in the conversation—were collected from American English speakers (five male, five female). Each speaker spoke for approximately 5 h. Smaller amounts of similar data are being collected for Japanese and Spanish. The principal objective is to better understand speech activities and their underlying rules by capturing them in speaking modes that exhibit very different ranges of variation. The reading of sentences spoken in conversation is particularly useful, because it allows us to directly compare acoustic attributes of linguistic forms in formal versus spontaneous speech. Several research projects that contrast conversation and more formal modes (two of which will be presented at this meeting) are being carried out. These include formant frequencies of unstressed vowels [Wallace]; acoustic properties of /ɚ/s [Horna); prosodic attributes of stressed and unstressed vowels; perception and acoustic correlates of degrees of emphasis. Ideas for future research, including a cross-language study of contractions used in conversation, will be proposed.
Some nonlinear aspects of the frequency response of a strongly excited gas bubble oscillator
Authors: Kim Dong H.
Published: October 2005

A numerical analysis is carried out for the nonlinear phenomena of the bubble oscillator. The model is based on the Keller's formulation for the bubble dynamics. Interpretation of the bubble interior is based on the formulation by Prosperetti. His formulation adopts the energy equation for the analysis of the bubble interior. The numerical simulation shows typical nonlinear phenomena in its frequency response. Among such nonlinear aspects are the jump phenomenon, the hysterisis effect, the shift of natural frequency of the system, and the appearance of superharmonic resonances. It is deduced that the nonlinear frequency response is dependent upon the initial condition of the bubble oscillator, and some multivalued frequency region can appear in the response curve. Nonlinear phenomena that appeared in the bubble oscillator are compared with those of the Duffing equation and it may be said that the bubble dynamic equation has similar nonlinear aspects to the Duffing equation.
A preliminary examination of the out-of-plane motion of the violin bridge
Authors: Marshall Kenneth D.
Published: October 2005

The vibrations of violin strings excited by bowing or plucking are mainly in the transverse and vertical directions, and are communicated to corpus through the rocking and vertical motions of the bridge. These factors have been extensively studied, but much less is known about how the longitudinal and torsional vibrations of the string, and the out-of-plane motions of the birdge, affect the sound radiated by the instrument. This talk will briefly review what has been learned to date about the out-of-plane vibrations of the bridge. Information is then presented showing: (1) the in-plane (y and z direction) motions of the bridge generally related at low frequency but quite different at higher frequency, and (2) the out-of-plane (x direction) bridge vibrations, distinctly different from the in-plane, and in several instances providing a negative resistance that may absorb energy from the vibrating strings. It is concluded that three-dimensional bridge motion should be considered to provide an improved understanding of violin dynamics.
Wide-angle one-way wave equations
Authors: Halpern Laurence , Trefethen Lloyd N.
Published: October 2005

A one-way wave equation, also known as a paraxial or parabolic wave equation, is a differential equation that permits wave propagation in certain directions only. Such equations are used regularly in underwater acoustics, in geophysics, and as energy-absorbing numerical boundary conditions. The design of a one-way wave equation is connected with the approximation of (1−s2)1/2 on [−1,1] by a rational function, which has usually been carried out by Padé approximation. This article presents coefficients for L2, L∞, and other alternative classes of approximants that have better wide-angle behavior. For theoretical results establishing the well posedness of these wide-angle equations, see the work of Trefethen and Halpern [‘‘Well-posedness of one-way wave equations and absorbing boundary conditions,’’ Math. Comput. 47, 421–435 (1986)].
Investigation of possibility of damage from the acoustically coupled seismic waveform from blast and artillery
Authors: Sabatier James M. , Raspet Richard
Published: October 2005

This article examines the source of ground vibrations in regions adjacent to artillery fire or explosive operations. Measurements have been performed to evaluate the possibility of damage from high levels of ground-borne vibration in the vicinity of residential homes. The result of these measurements demonstrates that the acoustically coupled seismic wave is much larger than the directly coupled seismic wave from large scale impulsive sources. The theory of acoustic-to-seismic coupling is extended to impulsive sources, in order to investigate the damage potential of the acoustic-to-seismic coupled wave with respect to the airborne wave. The results of the theory are compared to controlled measurements made using a small scale impulsive source. In addition, the theory and experiment are shown to be in good agreement with the large scale impulsive source with reasonable assumed values of the seismic velocities and layer depths. The theory is used to develop the acoustic-to-seismic coupling ratio for a typical blast wave over the expected range of wave speeds and porosities normally encountered. Worst-case scenarios are developed. It is demonstrated that it is unlikely that damage will occur to houses due to the acoustically coupled seismic wave unless the acoustic pulse pressure exceeds 162 dB.
Computation of the impulse diffraction of any obstacle by impulse ray modeling—Prediction of the signal distortions
Authors: Cassereau Didier , Guyomar Daniel
Published: October 2005

In this article, a numerical method of modeling the output signal of a transducer after reflection of the pulsed radiated wave on a reflector of arbitrary geometry is presented. This method, based on impulse ray modeling, corresponds to a discrete approach of the Kirchhoff-radiation integral: It leads to a numerical evaluation of the diffraction effects. The overall response can be written as a time convolution of the transducer impulse response with the radiation coupling function related to the reflector geometry. This linear system approach permits an easy explanation of the signal distortion due to the reflector geometry. After a presentation of the basic principles of the method and their justification, the model is applied to several geometrical configurations: tilted plane, cylindrical, and spherical reflectors of infinite acoustical impedance. The method is extended to model a focused transducer and a solid layer reflector of finite acoustical impedance.
A synthesis scheme for British English intonation
Authors: Willems Nico , Collier René , ’t Hart Johan
Published: October 2005

A synthesis scheme is proposed that provides British English utterances with a variety of acceptable artificial F0 contours. It is based on the acoustic analysis of a large corpus of (semi-) spontaneous utterances and on the perceptual evaluation of synthetic F0 contours that have been stylized and standardized. The scheme consists of three parts: (a) an explicit description of the perceptually relevant F0 changes, i.e., the pitch movements, as found in the corpus; (b) combination rules that specify the possible sequences of pitch movements in contours at the clause level; and (c) rules of sequence that govern the concatenation of pitch contours at the level of the sentence. The algorithm has been implemented in the form of a computer program that provides any input utterance with fully specified F0 values, which can be merged with its other source parameters in a (linear predictive code) LPC speech file. Thus the program can be incorporated in a text-to-speech system or be used as a research tool. A representative sample of synthetic F0 contours, generated by the program, has been evaluated in a formal listening experiment with 30 native British subjects. The results indicate that the artificial pitch contours sound as acceptable as their natural counterparts.
Pure-tone sensitivity of human infants
Authors: Olsho Lynne Werner , Koch Elizabeth G. , Carter Elizabeth A. , Halpin Christopher F. , Spetner Nancy B.
Published: October 2005

Pure-tone thresholds at frequencies ranging from 250 to 8000 Hz were estimated for 3-, 6-, and 12-month-old infants and for adults, using the Observer-based Psychoacoustic Procedure (OPP). Sounds were presented monaurally using an earphone. Psychometric functions of infants were similar to those of adults, although 3-month-olds had shallower functions at higher frequencies. The thresholds of 6- and 12-month-old infants were 10–15 dB higher than those of the adults, with the difference being greater at lower frequencies. This result is in general agreement with results from other laboratories. The thresholds of 3-month-olds were 15–30 dB higher than those of adults. The greatest difference between 3-month-olds and adults was at 8000 Hz. This threshold difference is smaller than that reported in earlier behavioral studies; higher thresholds at high frequencies have been previously reported for newborn and 3-month-old infants. The relative contributions of sensory and nonsensory variables to these age differences are discussed.
Modification of spontaneous and evoked otoacoustic emissions and associated psychoacoustic microstructure by aspirin consumption
Authors: Long Glenis R. , Tubis Arnold
Published: October 2005

The discovery that aspirin consumption can abolish spontaneous otoacoustic emissions [D. McFadden and H.S. Plattsmier, J. Acoust. Soc. Am. 76, 443–448 (1984)] provides a technique for further exploring the relation between otoacoustic emissions (spontaneous and evoked) and psychoacoustic threshold microstructure. Spontaneous emissions, delayed evoked emissions, synchronous evoked emissions, and threshold microstructure in four subjects were monitored before, during, and after consumption of 3.9 g of aspirin per day (three 325-mg tablets every 6 h) for 3 or 4 days. The changes in spontaneous emissions are consistent with the findings of McFadden and Plattsmier except that one spontaneous emission appeared to plateau at a reduced level above the noise floor during the last day and a half of the 3-day period of aspirin consumption. Evoked emissions and threshold microstructure were also reduced by aspirin consumption but persisted longer and recovered sooner. In most instances, the initial change in threshold microstructure was a trend to increased sensitivity (reduced thresholds), with a greater increase near threshold maxima than at threshold minima. Further reduction in the levels of the evoked emissions was accompanied by the eventual decrease in sensitivity (elevation of all thresholds).
Transient Rayleigh wave transmission along periodic and random grooved surfaces
Authors: Chamuel Jacques R. , Brooke Gary H.
Published: October 2005

New experimental findings generic to the problem of transient wave transmission in periodic and random structures are discussed. Specifically, results are presented on the transmission of transient Rayleigh waves on grooved surfaces where the groove depth is small compared to a wavelength. These results, obtained using two-dimensional ultrasonic models, reveal that, in direct contrast to continuous wave (cw) transmission, substantial energy can be transmitted along a grooved periodic surface at the Rayleigh wave Bragg frequency where the wavelength of the Rayleigh wave is twice the spatial wavelength of the grooved surface. The Bragg frequency energy arrives late over a wide time window. The transmission is characterized by a dominant main pulse followed by a ringing tail component. The spectrum of the main pulse has no major dips or peaks indicating that it is simply attenuated by the grooves (no discrimination against a specific frequency). Conversely, the spectrum of the tail portion for small grooves has a strong component near the Bragg frequency. The spectrum of the entire received signal has a dip at the ringing frequency indicating that the tail is out of phase with the main pulse. Shifts in the Bragg frequency occur due to the effects of topography on the Rayleigh wave velocity. Several different groove configurations are used to illustrate the effects of groove dimensions and spacing. Other results, obtained for unequally spaced grooves, show that destructive interference may eliminate the Bragg frequency ringing. The periodic grooves also initiate other Bragg frequency components associated with body waves and hybrid mode-converted surface/body waves.
An analytical, one-dimensional, standing-wave model of a linear active noise control system in a duct
Authors: Munjal M. L. , Eriksson L. J.
Published: October 2005

Assuming plane waves, and making use of the transfer matrices and electroacoustic analogies, a standing wave analysis of the active noise control system in a duct is presented incorporating the characteristics of the primary source as well as the auxiliary source. Analytical expressions have thus been derived for the ratio of the two source pressures and certain other ratios or relations of interest for complete or partial cancellation of noise downstream of the auxiliary source. The resulting closed-form expression for the filter transfer function H0 reveals the real role of the auxiliary source both when it is on and off, and the importance of the distance between the input microphone and the auxiliary source (generally, a loudspeaker). Finally, the analysis is extended to incorporate the convective and dissipative effects of the meanflow and viscothermal damping.
Acoustic backscattering at low grazing angles from the ocean bottom
Authors: Boehme H. , Chotiros N. P.
Published: October 2005

The measurement of acoustic backscattering at low grazing angles from the ocean bottom in a shallow water area near Charleston, South Carolina is described and the results of data analyses are compared with results reported earlier. It was found that, with fixed platforms resting on the bottom in shallow water at both test sites, interference in the form of backscatter from a rough sea surface is a significant problem. A modest frequency dependence and relatively strong azimuthal dependence for bottom backscattering strength were observed at both test sites. No strong relationship could be determined between bottom backscattering strength azimuthal dependence and bottom roughness characteristics.
High-frequency scattering from liquid/porous sediment interfaces
Authors: Williams Kevin L. , Hackman Roger H. , Trivett D. H.
Published: October 2005

A method for remote determination of the mean grain size of sand sediments is demonstrated. The method uses the backscattered signal from a bounded acoustic beam incident onto a water–sediment interface. The possibility of grain size determination stems from a localized enhancement in the backscattering for acoustic wavelengths of the same order as grain size. A phenomenological model that recaptures the overall structure of the experimental data is developed. The sediment is pictured as having a network of channels running through it, and the model developed is novel in its inclusion of channel effects as well as rough surface effects in modeling the backscattered signal.
F1 structure provides information for final-consonant voicing
Authors: Summers W. Van
Published: October 2005

Previous research has shown that F1 offset frequencies are generally lower for vowels preceding voiced consonants than for vowels preceding voiceless consonants. Furthermore, it has been shown that listeners use these differences in offset frequency in making judgments about final-consonant voicing. A recent production study [W. Summers, J. Acoust. Soc. Am. 82, 847–863 (1987)] reported that F1 frequency differences due to postvocalic voicing are not limited to the final transition or offset region of the preceding vowel. Vowels preceding voiced consonants showed lower F1 onset frequencies and lower F1 steady-state frequencies than vowels preceding voiceless consonants. The present study examined whether F1 frequency differences in the initial transition and steady-state regions of preceding vowels affect final-consonant voicing judgments in perception. The results suggest that F1 frequency differences in these early portions of preceding vowels do, in fact, influence listeners’ judgments of postvocalic consonantal voicing.
Modulation and gap detection for broadband and filtered noise signals
Authors: Formby C. , Muir K.
Published: October 2005

Modulation detection thresholds (as a function of sinusoidal amplitude modulation frequency) and temporal gap detection thresholds were measured for three low-pass-filtered noise signals (fc =1000, 2000, and 4000 Hz), a high-pass-filtered noise signal (fc =4000 Hz), and a broadband signal. The two latter noise signals were effectively low-pass filtered (fc =6500 Hz) by the earphone. Each of the filtered signals was presented with a complementary filtered noise masker. Modulation and gap detection thresholds were lowest for the broadband and high-pass signals. Thresholds were significantly higher for the low-pass signals than for the broadband and high-pass signals. For these tasks and conditions, the high-frequency content of the noise signal was more important than was the signal bandwidth. Sensitivity (s) and time constant (τ) indices were derived from functions fitted to the modulation detection data. These indices were compared with gap detection thresholds for corresponding signals. The gap detection thresholds were correlated inversely (ρ=−1.0, p<0.05) with s (i.e., smaller gap detection thresholds were correlated with greater sensitivity to modulation), but were not correlated significantly with τ, which was relatively invariant across signal conditions.
The application of linearly swept frequency measurements
Authors: Poletti Mark A.
Published: October 2005

The theory of linearly swept frequency measurements has been studied [M. A. Poletti, J. Audio. Eng. Soc. 36(6) (1988)]. This theory shows that the Fourier transform of a linear system impulse response may be produced as a function of scaled time by convolving, multiplying, and reconvolving the impulse response with infinite duration, complex linear frequency-modulated (FM) signals. The first convolution is implemented by injecting a linear FM signal into the system. The multiplication may be viewed as a synchronous detector that removes the carrier from the output of the system. The third operation may be viewed as a quadratic phase filter that removes the skewing distortion to produce the true transfer function as a function of time. The application of the theory using finite real signals is discussed. It is shown that for a finite duration impulse response a suitably time-limited signal may be injected into the system which produces the response that would be produced with an infinite signal, and that the response to a complex input signal may be produced by sequentially exciting the system with the real and imaginary parts of the complex signal. The second and third complex signals may also be successfully applied to produce the true frequency and phase response of the system without any errors due to the chosen sweep rate.
Finite difference approximation errors in sound intensity estimates of interfering sources
Authors: Shirahatti U. S. , Crocker Malcolm J. , Raju P. K.
Published: October 2005

In this article, theoretical expressions for the finite difference approximation errors in estimates of the sound intensity in the sound fields of interfering simple harmonic and random monopole point sources are given. Expressions are also given for the finite difference approximation error analysis of a simple harmonic point monopole over a reflecting plane. The method of images is used in the formulation. Sample calculations are included to show the effects of the microphone separation distance, the distance of the measurement location from the source, the geometrical arrangement of the sources, the phase difference between the two point sources, and their relative strengths. From the sample calculations, it is observed that increasing the microphone spacing increases the magnitude of the error level. It is also seen that the geometrical arrangement of the sources has a considerable effect on the error levels.
Hearing loss due to partly impulsive industrial noise exposure at levels between 87 and 90 dB(A)
Authors: Thiery L. , Meyer-Bisch C.
Published: October 2005

A cross-sectional epidemiological survey was carried out in a car-body workshop involving 234 workers divided into three groups according to age and noise exposure duration. Their hearing levels, determined by using a standardized audiometric testing procedure, were compared to those of a reference population not exposed to noise, to those of a population exposed to quasisteady noises at 95 dB(A), and also to ISO 1999-1987. Results reveal significant hearing loss after 9 years of exposure, greater than that from quasisteady noise exposure with the same equivalent continuous A-weighted sound-pressure level.
Finite amplitude sound near cutoff in higher-order modes of a rectangular duct
Authors: Hamilton Mark F. , TenCate James A.
Published: October 2005

The finite amplitude distortion of sound that is transmitted in a higher-order mode of a rectangular duct is investigated both theoretically and experimentally. A perturbation solution is used to determine the general form of the governing equations for source frequencies near cutoff, where dispersive wave interactions may frequently be ignored. A set of coupled first-order equations in terms of the harmonic amplitudes is obtained for the nondispersive interactions. Tube wall attenuation is included ad hoc. Experimental results are reported for the distortion of a 140-dB (re: 20 μPa) tone transmitted in the (1,0) mode of an air-filled rectangular duct. The cutoff frequency is 2470 Hz, and the theory for nondispersive interactions is in reasonable agreement with experimental results for source frequencies between approximately 2600 and 3300 Hz. Above 3300 Hz, the nonlinear interactions are strongly affected by dispersion. Below 2600 Hz, where thermoviscous absorption is very high, the predicted tube wall attenuation is unreliable.
Interaction of strain waves with noise in nonlinear elastic materials
Authors: Matsumoto Eiji
Published: October 2005

The nonlinear interaction of strain waves with noise is analyzed for one-dimensional nonlinear elastic materials. In a previous article [E. Matsumoto, J. Acoust. Soc. Am. 81, 1713 (1987)], the author showed that the variation of the spectra of strain waves is governed by an integrodifferential equation. According to the result, the variation of a weak wideband spectrum (noise) is of small order when it exists alone. However, this article shows that if there exist a noise and a strong wave with a narrow-band spectrum, secondary noises of the same order as the initial noise are generated. The frequency ranges of the secondary noises are determined by the combination of the frequency range of the initial noise and the central frequency of the strong wave.
Energy conservation for inhomogeneous plane waves
Authors: Leroy O. , Quentin G. , Claeys J. M.
Published: October 2005

In studying the reflection and transmission of inhomogeneous plane waves at liquid–solid interfaces, it is found that the theory predicts a minimum in the reflection coefficient at the Rayleigh angle. This phenomenon has not been predicted by previous treatments of homogeneous plane waves. A second surprising point is that the theory predicts that the modulus of the reflection coefficient becomes greater than unity for angles larger than the Rayleigh angle. A physical interpretation of this result is given, and it is shown that it is consistent with the conservation of energy.
Borehole modes in a cylindrical fluid-saturated permeable medium
Authors: Liu Hsui-Lin
Published: October 2005

Utilizing the borehole Stoneley wave generated in a permeable sample is a promising technique for measuring the frequency-dependent nature of permeability. The cylindrical boundary of the sample introduces complex extensional modes. In this article, numerical results of modes associated with an axially symmetric fluid-filled borehole in a cylinder of permeable medium are presented. Besides the Stoneley mode, there are two classes of extensional modes: the fast-wave modes and the slow-wave modes. These modes vary as functions of the sample permeability and size. In a highly permeable sample, the slow extensional modes, having velocity and attenuation near the Stoneley mode at low frequency, can obscure the identification of the Stoneley mode.
Comments on ‘‘Determination of natural frequencies of a thick spinning annular disk using a numerical Rayleigh–Ritz’s trial function’’ [J. Acoust. Soc. Am. 8
1, 357–369 (1987)]
Authors: Laura P. A. A. , Bambill D. V. , Rossit C. A.
Published: October 2005

This work provides additional reference citations appropriate to the interesting discussion made by Sinha in the Summary of his important contribution [J. Acoust. Soc. Am. 81, 357–369 (1987)]. Furthermore, it will be shown in the present letter that Rayleigh’s optimization criterion seems to yield excellent accuracy when applied to the determination of higher natural frequencies of structural elements carrying concentrated masses.
Intensity discrimination, increment detection, and magnitude estimation for 1-kHz tones
Authors: Viemeister Neal F. , Bacon Sid P.
Published: October 2005

Intensity difference limens (DLs) were measured over a wide intensity range for 200-ms, 1-kHz gated tones and for 200-ms increments in continuous 1-kHz tones. Magnitude estimates also were obtained for the gated tones over a comparable intensity range. The discrimination data are in general agreement with those from earlier studies but they extend them by showing: (1) good discrimination for gated tones over at least a 115-dB dynamic range; (2) a slight increase in the relative DL (ΔI/I) as intensity increases above 95 dB SPL; (3) smaller DLs for increments than for gated tones, with the difference approximately independent of intensity; (4) negligible ‘‘negative masking’’ when thresholds are expressed as intensity differences (ΔI). For two of the three subjects, magnitude estimates do not conform to a single-exponent power law for suprathreshold intensities. Over the middle range of intensities where a single exponent is appropriate, the value of the exponent is less than 0.1 for all subjects.
A cochlear model for acoustic emissions
Authors: Furst M. , Lapid M.
Published: October 2005

Variability in cochlear emission properties among different species, particularly humans and small mammals, and within individuals in the same species, is modeled by a cochlear nonlinear transmission line. The difference between humans and animals is largely explained by a lower cochlear input impedance in human ears than in cats, gerbils, or chinchillas. Inconstancy in emission properties among individual human or animal subjects is related to structural variability among ears, which can be the result of a nonuniform connection between the outer hair cells cilia and the tectorial membrane. These structural differences are modeled by a nonuniform cochlear partition resistance along the cochlear length. The model predicts that an ear which has a uniform cochlear partition resistance and an adequate cochlear input impedance will emit acoustic distortion products (ADP), but not spontaneous acoustic emission (SAE), nor click-evoked emission (CE). Only a nonuniform cochlea emits SAE and CE in addition to enhanced ADPs. The model predictions agree quantitatively with cochlear emission data from humans and animals.
On the forced vibration of simply supported rotating cylindrical shells
Authors: Huang Shyh-Chin , Soedel W.
Published: October 2005

The free and forced vibrations of rotating simply supported cylindrical shells are investigated. The equations of motion, which take into account the effects of initial tensions, are derived from Hamilton’s principle. The effects of rotation on the natural frequencies are first reviewed. Next, a new approach is developed for solving the general forced vibration response problem of rotating cylindrical shells. The solution in its final form is characterized by generalized coordinates. The orthogonality of trigonometric functions allows one to separate the solution such that the generalized coordinates associated with different rotational modes form a set of second-order differential equations and can be solved for independently. The solution is further simplified for the cases where flexural vibration predominates. An inverted problem, where the cylinder is stationary and the load is rotating around it, is solved too for comparison. Finally, analytical solutions to the constant point load, and to the harmonic point load in the radial direction, are obtained using the developed method. The influence of rotation on the forced vibration is then illustrated.
Rayleigh wave scattering at coastal regions
Authors: Deshwal P. S. , Mann K. K.
Published: October 2005

A theoretical study of Rayleigh wave scattering at the corner of a rigid quarter-space is formulated in the present article. The model fits with Rayleigh wave scattering at the coastal regions. A shallow ocean (x≥0, 0≤z≤h) of depth h is superimposed on the solid earth (z≥h) and the quarter-space (x≤0, z≥0) consisting of hard materials such as mountains at the coastal regions is rigid. The technique of Wiener and Hopf is used to obtain exact solutions. The scattered field behaves as cylindrical waves decaying exponentially at distant points and dominant near the scatterer. Numerical calculations for the amplitude of the scattered wave versus the wavenumber have been obtained.
Lateralization of complex binaural stimuli: A weighted-image model
Authors: Stern Richard M. , Zeiberg Andrew S. , Trahiotis Constantine
Published: October 2005

This article describes a new model that predicts the subjective lateral position of bandpass stimuli. It is assumed, as in other models, that stimuli are bandpass filtered and rectified, and that the rectified outputs of filters with matching center frequencies undergo interaural cross correlation. The model specifies and utilizes the shape and location of assumed patterns of neural activity that describe the cross-correlation function. Individual modes of this function receive greater weighting if they are straighter (describing consistent interaural delay over frequency) and/or more central (describing interaural delays of smaller magnitude). This weighting of straightness and centrality is used by the model to predict the perceived laterality of several types of low-frequency bandpass stimuli with interaural time delays and/or phase shifts, including bandpass noise, amplitude-modulated stimuli with time-delayed envelopes, and bandpass-filtered clicks. This model is compared to other theories that describe lateralization in terms of the relative contributions of information in the envelopes and fine structures of binaural stimuli.
Prediction of enhancement factor for small explosive sources in a stratified moving atmosphere
Authors: Walkden F. , West M.
Published: October 2005

A procedure for predicting attenuation from explosive sources, which employs an accurate ray tracing method, has been obtained. Ray tubes, each consisting of a group of four rays surrounding a central ray, are launched from an initial surface close to the source. An invariant property of the ray tubes is used to allow calculation of peak pressure attenuation between a sphere of radius 100 m, centered on the source, and given ground points. Comparisons of these predicted attenuations with measured values are presented.
Gaussian models for complex sound sources in the paraxial region
Authors: Sample John D.
Published: October 2005

A Gaussian superposition model is proposed for complex, directive sound sources to simplify the calculation of their paraxial sound fields. The source field is approximated by a superposition of many Gaussian beams, each calculated using one of two paraxial (or parabolic) approximations. Both paraxial approximations are examined in detail with regard to the minimum assumptions required and the range of validity. In particular, a phase error in the commonly used paraxial approximation for a Gaussian beam is examined to ensure that it will not result in amplitude errors in the superposition model. Finally, the model is used to calculate the sound field of a circular piston source and the results obtained are compared with the sound field calculated by more traditional methods.
Comparison of various modes of presenting sentence materials in tests of speech perception in noise
Authors: Theodoridis George C. , Schoeny Zahrl G.
Published: October 2005

This study compares alternative modes of presenting sentences in testing situations where noise is employed and where the required response is only one word in the sentence. The purpose is to establish the extent to which contextual information is transmitted to the listener in the following four presentation modes: (1) acoustical presentation of the test word under noise and written presentation of the rest of the sentence (mode W); (2) acoustical presentation of sentence and test word under uniform noise (mode A); (3) superposition of the previous two modes (mode B); and (4) acoustical presentation of the test word under noise in one ear, immediately following the presentation of the rest of the sentence without noise in the other ear (mode C). Modes B and C are found to be essentially equivalent to mode W. When mode A is used, the intelligibility of the test word is substantially lower than with mode W, especially at low signal-to-noise (S/N) ratios. These results are particularly relevant to testing situations where the primary intent is to assess the utilization of contextual information in perceiving speech.
Velocity control and the mechanical impedance of single degree of freedom electromechanical vibrators
Authors: Johnson Michael P.
Published: October 2005

Most of the transducer devices used in present day sonar arrays are usefully approximated as single degree of freedom devices. Such devices exhibit a minimum in their mechanical input impedance to their radiating face at the fundamental resonance frequency. This minimum in impedance, leading to possible wide fluctuations in velocity across the array, can result in deterioration of electroacoustic performance and possibly disastrous results to hardware if left unchecked. The standard technique used to prevent this is attributed to D. L. Carson [J. Acoust. Soc. Am. 34, 1191–1196 (1962)] and essentially provides an electrically induced antiresonance near the mechanical resonance frequency. It is shown that this technique results in two minima, one residing on each side of the previous minimum. The resulting bandwidth over which velocity control of the array can be achieved is closely tied to the bandwidth between these minima. The relative locations of these minima are dependent only on effective electromechanical coupling coefficients and the ratio of the electrical antiresonance to mechanical resonance frequencies. This bandwidth appears to have a practical limit of approximately an octave.
Fast search strategy in a large vocabulary word recognizer
Authors: Gupta V. N. , Lennig M. , Mermelstein P.
Published: October 2005

In this article, a fast search algorithm is presented for generating word hypotheses for a 75 000-word vocabulary, speaker-trained, isolated word recognizer. The algorithm is envisioned as the first pass of a total recognition system generating a small number of hypotheses with rough likelihood estimates, to be followed by more detailed hypothesis evaluation. The possible word choices are restricted by estimating the number of syllables in the unknown word using a hidden Markov model (HMM) for syllables. A heuristic search algorithm then searches through a sequence of syllable networks to find the most likely word candidates. Arcs in the syllable network correspond to phonemes. The assumption that the likelihoods of these phoneme arcs are independent of the phonetic context allows us to convert the search through a large tree into a search through a much smaller network or graph. The computational requirements are reduced by roughly a factor of 70 compared to estimating the exact likelihood scores for the 75 000 words. This fast search algorithm is called the syllabic graph search. The recognition accuracy obtained for the syllabic graph search approaches that obtained using the exact likelihood scores for the phoneme sequences.
Detection of linear frequency glides as a function of frequency and duration
Authors: Dooley Gary J. , Moore Brian C. J.
Published: October 2005

This article compares frequency discrimination thresholds for four conditions, using a two-interval forced-choice task: (1) discrimination of a difference in center frequency for two pulsed tones (DLF); (2) discrimination of a steady tone from an up-frequency glide with the same mean frequency (UP-DL); (3) discrimination of a steady tone from a down-frequency glide with the same mean frequency (DOWN-DL); (4) discrimination of an up-frequency glide from a down-frequency glide with the same mean frequency (UPVSDOWN-DL). All glides were linear in Hz/s. Experiment 1 measured thresholds as a function of center frequency over the range 500–8000 Hz in 1-oct steps, for a fixed duration of 500 ms. The variation of glide thresholds with frequency was similar to that for the DLFs. Experiment 2 measured thresholds as a function of duration over the range 50–750 ms, for a fixed center frequency of 2000 Hz. The DLFs decreased monotonically with increasing duration. The glide thresholds decreased as duration increased from 50 to 100 ms, but did not change markedly beyond that. In both experiments, DLFs and UPVSDOWN-DLs were similar. UP-DLs and DOWN-DLs were typically two to three times greater than DLFs and UPVSDOWN-DLs, and UP-DLs tended to be larger than DOWN-DLs at center frequencies up to 2000 Hz. Experiments 3 and 4 measured thresholds for detecting glides in frequency when fixed glides in level were superimposed on all stimuli. The glides in level had only a small effect on the frequency-glide thresholds. The results are discussed in terms of their compatibility with Zwicker’s [Acustica 6, 365–381 (1956)] excitation-pattern model of modulation detection and in terms of their implications for sampling theories of glide detection.
Sound transmission experiments from an impulsive source near rigid wedges
Authors: Li Saimu , Clay C. S.
Published: October 2005

Experimental sound transmissions in air from a spark source to a small microphone were made near rigid wedges. Two types of experiments were made. The first experiments were transmissions within an approximately 12° wedge and a 52° wedge. The Biot–Tolstoy exact wedge solution [I. Tolstoy and C. S. Clay, Ocean Acoustics (American Institute of Physics, New York, 1987), 2nd ed.] was used to calculate the theoretical impulse responses. Within the 12° and 52° wedge, the solution gives a finite set of images and a diffraction arrival. Theory and experiments matched. The second type of experiments measured the image or ‘‘optical’’ reflection as the reflection point was moved to the edge of a half-plane and tested a Fresnel–Kirchhoff solution. The exact wedge solution gives a relative reflection amplitude of 1 compared to the reflection from an infinite plane. The Fresnel–Kirchoff solution of Trorey [A. W. Trorey, Geophysics 35, 762–784 (1970)] gives a relative signal of 1/2. Experiments were made near vertical incidence over a 270° wedge. They confirmed the correctness of the exact wedge solution and the incorrectness of the Trorey solution.
Equivalent temperature of sonoluminescence by steady and pulsed ultrasound irradiation for different gas–water systems
Authors: Johri G. K. , Ciuti P. , Iernetti G. , Tomasini F.
Published: October 2005

The equivalent temperature of sonoluminescence is analyzed by focused steady and pulsed ultrasonic irradiation at 0.7 MHz for different monoatomic and diatomic gases saturating the distilled water. Transducer voltage, pulse time, total excitation time, and pulse duty ratio have been varied. The intensities of sonoluminescence in a yellow, a blue, and an ultraviolet wavelength range are measured using corresponding filters and three photomultiplier tubes viewing a cell of 160 cm3 in volume. The data are taken near the threshold and well inside the region of developed cavitation. The equivalent temperature decreases by decreasing the inverse pulse duty ratio from the threshold value down to the steady irradiation; it increases by increasing the sound pressure amplitude and decreases by increasing the pulse time and the excitation time. The equivalent temperature increases by increasing the atomic weight of the monoatomic gas saturating the water when the cavitation zone is in a nonsaturated condition, i.e., near the incipient threshold of the pulsed irradiation. The equivalent temperature of the sonoluminescence is analyzed in the initial and final stages of development of the cavitation zone, which correspond to bubble densities different by many orders of magnitude.
Surface wave characteristics of fluid-loaded multilayered media
Authors: Nayfeh Adnan H. , Taylor Timothy W.
Published: October 2005

Theoretical analyses are presented for the interaction of ultrasonic waves with multilayered media. The wave is supposed to be incident from a liquid, at an arbitrary angle, upon a plate consisting of an arbitrary number of different material layers. The composite plate is supported from the bottom by a solid half-space. It is assumed that all solid interfaces are either rigidly or smoothly bonded. Reflection and transmission coefficients are derived for the total system. By examining the behavior of the reflection coefficient, all of the propagation characteristics are identified. Numerical results are given in order to delineate the influence of the plate material orderings on the propagation process. Included are also comparisons of results obtained under the rigid and the smooth bonding assumptions.
Effects of radial layering when logging in saturated porous formations
Authors: Schmitt D. P.
Published: October 2005

In a fluid-filled borehole embedded in a radially semi-infinite saturated porous formation with a permeable borehole wall, numerical simulations have shown that the Stoneley wave dispersion and attenuation are sensitive to the in situ permeability. In this article, the configuration of a damaged (invaded or flushed) zone resulting from a general formulation, based on the Thomson–Haskell method, is used to propagate the wave field through several saturated porous layers. The two phase media are modeled following a modified Biot’s theory. Whatever the boundary conditions at the borehole wall, the Stoneley wave integrates the properties of the inner layer in the entire frequency range. With a permeable borehole wall, the Stoneley wave dispersion and attenuation are mainly representative of the rheological properties of the first layer. Such a coupling increases with increasing thickness and/or decreasing velocities, porosity, and saturant fluid mobility of the inner layer. Of course, it also increases with increasing frequency. As a result, the estimation of the in situ permeability of the virgin formation, based on the Stoneley wave characteristics, is ill-posed. Whatever the configuration, the phase velocity and attenuation of the first pseudo-Rayleigh mode start at those of the virgin formation. The low-frequency (high-velocity) part of the pseudo-Rayleigh wavetrain can then be used for the indirect estimation of the virgin formation shear wave characteristics. Higher in frequency, the inner shell becomes the controlling layer. Full wave synthetic microseismograms illustrate these behaviors in the time domain.
Acoustic beam propagation in a turbulent ocean
Authors: Tarng J. H. , Yang C. C. , McDaniel S. T.
Published: October 2005

Effects of random fluctuations of sound speed in the ocean on acoustic beam propagation are investigated. These effects are especially interesting because of the existence of the vertical sound-speed profile and hence the occurence of multiple-path propagation. The path integral technique is utilized to compute the average intensity. By examining the variations of the average intensity, the following conclusions are drawn: Random fluctuations not only smooth the oscillations of the intensity, which are due to the interference among multiple paths, but also broaden the beam. It is found that this broadening is asymmetric and the energy in the beam moves toward the deeper side of the beam. This phenomenon is attributed to the effect of the vertical sound-speed profile.