bluuebunny/crossref_metadata_2025 huggingface dataset:
Bispectral analysis of parametric and nonlinear phenomena
Authors: Choi D. , Powers E. J. , Chang J-H. , Stearman R. O.
Published: October 2005

A parametrically excited system at a frequency fp near the sum of two natural frequencies of the system usually exhibits the so-called combination resonances at frequencies fa and fb which are close to the corresponding natural frequencies. This interesting phenomenon in which a single spectral component of the excitation induces two spectral components in the response cannot be identified by conventional spectral analysis. In the case of the combination resonances, a phase coherence exists between the two resonance modes and the excitation. This coherence can be detected by a triple correlation in the frequency domain between the spectral components at fp, fb, and fp. This triple correlation known as bicoherence is effective in studying the combination resonances. It is also useful in detecting nonlinear interactions that occur among various resonance modes as the amplitude of the excitation is increased. The applicability of digital bispectral analysis in studies of the parametric and nonlinear phenomena is demonstrated by analyzing vibration data from a parametrically excited cantilever beam. Results for both sinusoidal and random excitations are presented. [The authors' work on bispectral analysis is supported in part by the DoD Joint Services Electronics Program.]
Dissipative, nonlinear acoustics in fluids having positive and negative nonlinearity
Authors: Cramer M. S. , Watson L. T. , Pelz W. , Kluwick A.
Published: October 2005

Recent studies by the first and last authors have shown that the nonlinear acoustics of fluids in which the nonlinearity parameter 1 + B/2A changes sign is governed by a cubic Burger equation. Numerical solutions to this equation have been obtained by combining a collocation scheme in space and backward differencing in time. These will be presented and compared to exact solutions of the inviscid equations. New results include the viscous structure of the collision between expansion and compression shocks. Conditions under which flows are self-similar will also be presented.
How loudly should you hear your colleagues and yourself
Authors: Ternström Sten , Sundberg Johan
Published: October 2005

A choir singer needs to hear both the sound of his/her own voice and the sound of the other choir members. If either of these signals becomes too loud, problems can be assumed to arise. The present study investigates the importance of the amplitude ratio between the sound of one's own voice and the sound of an external reference signal. Nine male choir singers were asked to sing in unison with synthetic reference vowel stimuli presented over earphones. In the earphones they also heard the sound of their own voice as picked up by a microphone in front of the mouth. The SPL of the reference stimuli was varied over a range of 40 dB, while the subjects were asked always to sing at a constant SPL, as indicated by a level meter. The fundamental frequency agreement between the reference and the subjects' responses was analyzed. The fundamental frequency of the responses depended strongly on the SPL of the reference in the case of the vowel /u/, presumably because of a pitch-amplitude dependence, which, however, was compensated for in the analysis. It was found that the fundamental frequency agreement between the reference vowels and the corrected responses was approximately constant over a dynamic range of 20 dB of the reference vowels. Outside this range, choir singers tended to fail in matching the pitch of the external reference.
Effects of cochlear hearing loss on perceptual grouping cues in competing-vowel perception
Authors: Rossi-Katz Jessica A. , Arehart Kathryn Hoberg
Published: October 2005

This study compared how normal-hearing listeners (NH) and listeners with moderate to moderately severe cochlear hearing loss (HI) use and combine information within and across frequency regions in the perceptual separation of competing vowels with fundamental frequency differences (ΔF0) ranging from 0 to 9 semitones. Following the procedure of Culling and Darwin [J. Acoust. Soc. Am. 93, 3454–3467 (1993)], eight NH listeners and eight HI listeners identified competing vowels with either a consistent or inconsistent harmonic structure. Vowels were amplified to assure audibility for HI listeners. The contribution of frequency region depended on the value of ΔF0 between the competing vowels. When ΔF0 was small, both groups of listeners effectively utilized ΔF0 cues in the low-frequency region. In contrast, HI listeners derived significantly less benefit than NH listeners from ΔF0 cues conveyed by the high-frequency region at small ΔF0’s. At larger ΔF0’s, both groups combined ΔF0 cues from the low and high formant-frequency regions. Cochlear impairment appears to negatively impact the ability to use F0 cues for within-formant grouping in the high-frequency region. However, cochlear loss does not appear to disrupt the ability to use within-formant F0 cues in the low-frequency region or to group F0 cues across formant regions.
The tongue stops here: Ultrasound imaging of the palate
Authors: Epstein Melissa A. , Stone Maureen
Published: October 2005

This letter presents a method for imaging the palate and extracting the palate contour from ultrasound images. Ultrasound does not usually capture the palate because the air at the tongue surface reflects the ultrasound beam back to the transducer. However, when the tongue touches the palate during a swallow, the ultrasound beam is transmitted through the soft tissue until it reaches and is reflected by the palate. In combination with tongue contours, the palate contour has the potential for disambiguation of the tongue surface, registration of images within and across subjects, and calculation of phonetically important measures.
Tactile information transfer: A comparison of two stimulation sites
Authors: Summers Ian R. , Whybrow Jon J. , Gratton Denise A. , Milnes Peter , Brown Brian H. , Stevens John C.
Published: October 2005

Two experiments on the discrimination of time-varying tactile stimuli were performed, with comparison of stimulus delivery to the distal pad of the right index finger and to the right wrist (palmar surface). Subjects were required to perceive differences in short sequences of computer-generated stimulus elements (experiment 1) or differences in short tactile stimuli derived from a speech signal (experiment 2). The pulse-train stimuli were distinguished by differences in frequency (i.e., pulse repetition rate) and amplitude, and by the presence/absence of gaps (∼100-ms duration). Stimulation levels were 10dB higher at the wrist than at the fingertip, to compensate for the lower vibration sensitivity at the wrist. Results indicate similar gap detection at wrist and fingertip and similar perception of frequency differences. However, perception of amplitude differences was found to be better at the wrist than at the fingertip. Maximum information transfer rates for the stimuli in experiment 1 were estimated at 7bitss−1 at the wrist and 5bitss−1 at the fingertip.
Informational masking for simultaneous nonspeech stimuli: Psychometric functions for fixed and randomly mixed maskers
Authors: Durlach Nathaniel I. , Mason Christine R. , Gallun Frederick J. , Shinn-Cunningham Barbara , Colburn H. Steven , Kidd Gerald
Published: October 2005

Sensitivity d′ and response bias β were measured as a function of target level for the detection of a 1000-Hz tone in multitone maskers using a one interval, two-alternative forced-choice (1I-2AFC) paradigm. Ten such maskers, each with eight randomly selected components in the region 200–5000Hz, with 800–1250Hz excluded to form a protected zone, were presented under two conditions: the fixed condition, in which the same eight-component masker is used throughout an experimental run, and the random condition, in which an eight-component masker is chosen randomly trial-to-trial from the given set of ten such maskers. Differences between the results obtained with these two conditions help characterize the listener’s susceptibility to informational masking (IM). The d′ results show great intersubject variability, but can be reasonably well fit by simple energy-detector models in which internal noise and filter bandwidth are used as fitting parameters. In contrast, the β results are not well fit by these models. In addition to presentation of new data and its relation to energy-detector models, this paper provides comments on a variety of issues, problems, and research needs in the IM area.
Male sperm whale acoustic behavior observed from multipaths at a single hydrophone
Authors: Laplanche Christophe , Adam Olivier , Lopatka Maciej , Motsch Jean-François
Published: October 2005

Sperm whales generate transient sounds (clicks) when foraging. These clicks have been described as echolocation sounds, a result of having measured the source level and the directionality of these signals and having extrapolated results from biosonar tests made on some small odontocetes. The authors propose a passive acoustic technique requiring only one hydrophone to investigate the acoustic behavior of free-ranging sperm whales. They estimate whale pitch angles from the multipath distribution of click energy. They emphasize the close bond between the sperm whale’s physical and acoustic activity, leading to the hypothesis that sperm whales might, like some small odontocetes, control click level and rhythm. An echolocation model estimating the range of the sperm whale’s targets from the interclick interval is computed and tested during different stages of the whale’s dive. Such a hypothesis on the echolocation process would indicate that sperm whales echolocate their prey layer when initiating their dives and follow a methodic technique when foraging.
Scattering of ultrasonic waves by defective adhesion interfaces in submerged laminated plates
Authors: Leiderman Ricardo , Braga Arthur M. B. , Barbone Paul E.
Published: October 2005

We present an analytical-numerical method to simulate time-harmonic ultrasonic scattering from nonhomogeneous adhesive defects in anisotropic elastic laminates. To that end, we combine the quasistatic approximation (QSA) with a very high-order (tens or hundreds of terms) regular perturbation series to allow modeling of nonuniform interfacial flaws. To evaluate each term in the perturbation series, we use a recursive algorithm based on the invariant imbedding method. It is applicable to solve wave propagation problems in arbitrarily anisotropic layered plates and it is stable for high frequencies. We demonstrate examples of convergence and divergence of the perturbation series, and validate the method against the exact solution of plane wave reflection from a layered plate immersed in water. We present a further example of scattering of a Gaussian beam by an inhomogeneous interfacial flaw in the layered plate. We discuss how results of our simulations can be used to indicate the frequencies and angles of incidence where scattering from potential defects is strongest. These parameters, presumably, offer the best potential for flaw characterization.
Estimation of radius and thickness of a thin spherical shell in water using the midfrequency enhancement of a short tone burst response
Authors: Li Wei , Liu G. R. , Varadan V. K.
Published: October 2005

The midfrequency enhancement phenomenon for tone burst backscattering by thin spherical shells in water has been discussed by several investigators. In their works, it is found that the earliest elastic tone burst echo is enhanced relative to the specular reflection, and this enhancement is mainly due to the lowest subsonic antisymmetric Lamb wave. In this paper, the tone burst backscattering obtained from the convolution integral of the incident tone burst and the impulse response by a submerged spherical shell is investigated to display the midfrequency enhancement. The modified ray approximations are used to calculate the echo contributions from different Lamb waves. The numerical results show that the ratio of a∕h and the dimensionless echo delay have nearly linear relationship with the frequency of greatest enhancement. Based on this property, two linear approximate equations are formulated to evaluate the radius and thickness of a thin spherical shell. A simple method is developed to estimate the frequency of greatest enhancement and the corresponding echo delay from a short tone burst echo with a higher carrier frequency. The evaluated results show that the present method is effective on determination of the radius and thickness of a thin spherical shell in water.
Fluctuations in sound transmission through internal waves associated with the thermocline: A computer model for acoustic transmission through sound velocity fields calculated from thermistor chain, CTD, XBT, and acoustic backscattering
Authors: Baxter Lincoln , Orr Marshall H.
Published: October 2005

Data sets obtained from towed thermistor strings, instrumented tow bodies, conductivity temperature depth sensors, expendable bathythermographs, sound velocimeters and high-frequency acoustic backscattering systems provide detailed information on the temporal and spatial variability of the sound velocity field in the upper ocean. The data sets show that internal waves and other small scale fluid phenomena such as instabilities can significantly perturb the sound velocity field and consequently sound propagation. Little attention has been focused on the magnitude of short-range, high-frequency acoustic propagation variability caused by internal wave field and/or water mass variability. A ray trace program package has been developed which numerically integrates with a fourth-order Runge–Kutta method the time dependent eikonal equations through a range dependent sound velocity field. The sound-speed profiles, which are calculated from field data, are entered into a matrix with sizes larger than the numerical integration steps. Consequently, the profiles are interpolated between matrix steps with the bicubic interpolation technique of Akima. Calculations for sound-speed fields perturbed by internal waves show that at a fixed position the intensity of the sound intensity field can vary by as much as 20 dB as a function of time.
Method for computing the sound power of machines based on the Helmholtz integral
Authors: Koopmann Gary H. , Benner Henry
Published: October 2005

A computational method is presented for assessing the sound power characteristics of machines. The method, which is based upon a Helmholtz integral formulation, requires a knowledge of the geometry and the modal characteristics of a machine’s vibrating surfaces so that the pressure on the surface can be computed. Closed form integration of the associated surface integrals is carried out in a piecewise manner over planar surface elements in the shape of rectangles or triangles. This choice of element allows the grid geometries associated with the acoustic power computations to be made identical to those used in existing structural modal analysis methods. In this way, the sound power characteristics of a given machine can be computed in terms of the sound power radiated by each of the structural modes comprising the overall response. The structural modes can then be ranked in order of their radiation efficiency for purposes of noise control treatments. The accuracy of the method is demonstrated by calculating the pressure on the surface of a uniformly pulsating sphere and of an oscillating sphere for values of ka (dimensionless frequency) up to 10.
Psychophysical studies for two multiple-channel cochlear implant patients
Authors: Tong Y. C. , Clark G. M. , Blamey P. J. , Busby P. A. , Dowell R. C.
Published: October 2005

Psychophysical studies were conducted on two multiple-channel cochlear implant patients to examine the nature of the hearing sensations produced by electrical stimulation of auditory nerve fibers using electrodes at different sites in the scala tympani (one electrode at a time). Both time-invariant stimuli, whose parameter values did not vary in time, and time-varying stimuli, specified by a linear variation in parameter values, were used. A sharpness ranking study using time-invariant signals suggested that the hearing sensations produced by different electrodes varied from dull to sharp in an apical to basal direction in the scala tympani. A categorization study showed that the hearing sensations produced by two adjacent electrodes (1.5 mm apart) were rarely confused for a restricted range of time-invariant pulse rates. Discriminability studies by a same–different procedure for stimuli with pulse rates below 250 pps showed: (1) relative difference limens of 6% to 12% for time-invariant pulse rates, and 9% to 13% for time-varying pulse rates; (2) stimuli with time-varying electrode position differing in the direction of electrode trajectory were readily discriminated; and (3) the discrimination of time-varying pulse rates deteriorated with decreases in the duration of the variation, while the discriminability of single-electrode trajectories was the same for three durations: 25, 50, and 100 ms. A speech processing strategy was also proposed on the basis of these results.
On the status of temporal cues to phonetic categories: Preceding vowel duration as a cue to voicing in final stop consonants
Authors: Wardrip–Fruin Carolyn
Published: October 2005

The duration of the preceding vowel has been called a primary and even necessary cue to voicing in final stop consonants. The results of this investigation suggest that in natural speech, vowel duration differences are probably neither necessary nor adequate cues to this distinction and that voicing during closure may be required to disambiguate final voiced stops. The stimuli were 52 one-syllable words recorded by two speakers and subjected to an analog-to-digital process and to linear predictive coding. Deletions, compressions, and expansions of segments of these 104 syllables produced 521 stimulus items which were randomized and presented to 12 adult listeners who judged the syllables to end in a voiced or voiceless stop. Though syllable duration was a more significant cue to the voicing feature than was vowel duration, syllable duration was not a necessary cue in that, even at the extremes of syllable length, syllables with final transition and/or final segment information intact did not effect a crossover in voicing judgment. Syllable duration was not an adequate cue to the voicing feature in that syllables without final transition and final segment information were not heard as better than 60 percent voiced at any syllable duration. By contrast, voicing during closure determined the voicing decision across the full range of syllable durations.
Question of dynamics of mass acceleration on elastic members
Authors: Raske T. F.
Published: October 2005

An analysis based on linear theory is presented for a mass moving on the surface of an elastic member. Major emphasis is directed towards the development of the three-dimensional components of mass acceleration on a plate. It is shown that the transverse component is given by the well-known total derivative of plate deflection while the in-plane components appear to be new to the literature. An example of a rolling mass traversing a beam is included.
Further studies on acoustic impedance of major bovine blood vessel walls
Authors: Geleskie J. V. , Shung K. K.
Published: October 2005

Data on ultrasound velocity and specific impedance of major bovine blood vessel walls are compared to structural protein content measured by hydroxypoline assay as well as total solid tissue content of these tissues. Results indicate that acoustic velocity in these tissues is determined largely by the collagen and elastin contents of the tissues. However, acoustic impedance, which is the product of density and velocity, shows a stronger dependence on the total tissue content, suggesting that other solid tissues, in particular, muscle in blood vessel walls, may also play a significant role in the determination of acoustic impedance.
Determination of the nonlinearity parameters for liquids using thermodynamic constants
Authors: Endo Harumi
Published: October 2005

On the basis of thermodynamic relations, the expression for the nonlinearity parameter B/A is obtained in the form of a polynomial in terms of the ratio of specific heats. The values of B/A for liquids are calculated by using the available thermodynamic data. In the case of 35%o seawater, comparison between our approach and the conventional one using the T and P coefficients of sound velocity is within 1.5%.
Anomalous infrasound generated by the Alaskan earthquake of 28 March 1964
Authors: Young Jessie M. , Greene Gary E.
Published: October 2005

In this paper we present and analyze data recorded at three microphone arrays (Boulder, Colorado; Boston, Massachusetts; and Washington, DC) associated with the Alaskan earthquake of 03 h 36 min 13 s UT, 28 March 1964 (61.05N, 147.50W). We show that the recordings from all three stations contain not only the epicentral and locally generated air waves reported by other authors, but also contain evidence of atmospheric radiation apparently generated from seismic surface waves along the Rocky Mountains. The latter became decoupled from the surface wave and traveled at about 314 m/s through the air to the arrays.
Caustic corrections using coherence theory
Authors: Frankenthal Shimshon , Beran M. J. , Whitman A. M.
Published: October 2005

In the vicinity of a caustic the intensity is very different from that calculated on the basis of geometrical acoustics. Using the basic formulation of coherence theory we show here how the correct intensity may be obtained when the source has a finite (i.e., nonzero) size. We use a two-scale expansion to include the correction term to the geometric acoustic calculation (here already modified to include the effect of a finite source). It is shown that in the limit of a point source the results are the same as those previously obtained. Finally a numerical example is presented.
Analytical model of the truck tire vibration sound mechanism
Authors: Keltie Richard F.
Published: October 2005

A theoretical model is developed to describe the sound radiation by the surface vibration of in-service truck tires. The tire is modeled as an infinitely long incomplete circular cylindrical shell. The effects of inflation pressure and structural damping are included. The normal displacement, velocity, and acceleration resulting from a fluctuating load are determined using Flügge’s thin shell theory. Through numerical integration of the surface acoustic intensity, the radiated sound power is calculated as a function of damping, inflation pressure, and bending stiffness. Results indicate that the forced acoustic response is insensitive to small changes in the material loss factor and the bending stiffness. The inflation-induced membrane stresses determine the acoustic response character to a large extent and total neglect of the bending stiffness does not seriously affect the calculated sound power. The basic sound radiation mechanism is shown to be the damped progressive wave field on the structure in the vicinity of the applied force. The results indicate that the potential sound reduction might best be approached through study of the tire loading and vibration response mechanisms.
Multiple scattering of acoustic waves by random distribution of discrete spherical scatterers with the quasicrystalline and Percus–Yevick approximation
Authors: Tsang L. , Kong J. A. , Habashy T.
Published: October 2005

In studying the multiple scattering of acoustic waves by random distributions of scatterers with appreciable concentration, the approach of quasicrystalline approximation together with hole correction (QCA–HC) has been a common method. We show that such an approach will give rise to negative attenuation rate indicating a growth of the coherent wave in space which is a nonphysical solution. To derive better results, we employ the solution of the Percus–Yevick equation together with quasicrystalline approximation (QCA–PY) to study multiple scattering of acoustic waves by discrete spherical scatterers. Waterman’s T matrix formalism is used in formulating the multiple scattering problem. Closed form solutions are obtained for the effective propagation constants in the low-frequency limit. Effective propagation constants at higher frequencies are calculated by numerical methods. The result of QCA–HC for the two-dimensional case is also discussed.
Vibration isolation of a damped skeletal machine foundation—Theory and experiment
Authors: Lundén Roger , Kamph Esse
Published: October 2005

The vibrational behavior of a lightweight skeletal machine foundation (grillage) is investigated numerically and experimentally. For the vibration isolation problem, a combination of ’’blocking masses’’ and discrete and distributed additive damping is shown to provide desired vibrational properties in a broad frequency interval. Considering the reduction of a given set of resonance responses, optimally distributed partial damping treatment is found to be an economic measure. In the numerical study, a theory for damped second-order Rayleigh–Timoshenko beams has been applied. The computer method used has proven to be an effective numerical tool in attacking general vibration isolation problems.
Superresolution ultrasonic imaging system by forced vibration of object
Authors: Sato Takuso , Ikeda Osamu , Akiyama Yoshiyuki , Hatsuzawa Takeshi
Published: October 2005

A superresolution ultrasonic imaging method by the forced vibration of an object is proposed. This method is based on the following fact: when a periodically vibrating object is illuminated, the signal components returned from different points on the object give corresponding different sets of the Fourier expansion coefficients. An optimum algorithm for estimating the object is formulated for the case of a general array imaging system. The algorithm obtained is a kind of deconvolution operation for the Fourier expansion coefficients of the received signal to obtain the coefficients of reflection of the object. The spacing of the image reconstruction points and the dimension of the deconvolving matrix are related to the size and the numbers of resolvable elements, respectively. It is shown, in terms of the effective rank of the matrix, that the resolution is increased with the increase of the amplitude or frequency of the vibration. Superresolution imaging is possible if the spacing is chosen so that it is less than a half of the wavelength of the ultrasonic wave. The effectiveness of the method is shown by numerical analyses, and is confirmed by basic experiments.
An investigation of the validity of high-frequency audition
Authors: Fausti S. A. , Rappaport B. Z. , Schechter M. A. , Frey R. H.
Published: October 2005

In this investigation, a masking experiment was utilized to explore the validity of high-frequency audition. Threshold shifts produced by a narrow-band noise with sharp filter slopes and variable center frequency were determined for pure-tone stimuli from 8000 to 14 000 Hz. Subjects were young adults with normal hearing from 250 through 8000 Hz, and with high-frequency thresholds comparable to those obtained in a previously conducted normative survey. After pure-tone thresholds were obtained for each test frequency, a narrow-band masker was presented ipsilateral to the pure-tone stimulus with center frequency equal to the pure tone. The masker was adjusted to an intensity level necessary to shift the pure-tone threshold approximately 17 dB. The center frequency of the masker was then decreased in discrete steps with the pure-tone threshold re-established at each step. The experimental results, as demonstrated by release-from-masking functions, are consistent with the expectation of increased masker effectiveness as the center frequency of the masker approximates the test frequency. The findings of this investigation suggest that responses to high-frequency auditory stimulation are the result of high-frequency perception, and not the perception of some lower frequency distortion process.
Algorithm for extraction of pitch and pitch salience from complex tonal signals
Authors: Terhardt Ernst , Stoll Gerhard , Seewann Manfred
Published: October 2005

A procedure is described for the automatic extraction of the various pitch percepts which may be simultaneously evoked by complex tonal stimuli. The procedure is based on the theory of virtual pitch, and in particular on the principle, that the whole pitch percept is dependent both on analytic listening (yielding spectral pitch), and on holistic perception (yielding virtual pitch). The more or less ambiguous pitch percept governed by these two pitch modes is described by two pitch patterns: the spectral-pitch pattern, and the virtual-pitch pattern. Each of these patterns consists of a number of pitch (height) values, and associated weights, which account for the relative prominence of every individual pitch. The spectral-pitch pattern is constructed by spectral analysis, extraction of tonal components, evaluation of masking effects (masking and pitch shifts), and weighting according to the principle of spectral dominance. The virtual-pitch pattern is obtained from the spectral-pitch pattern by an advanced algorithm of subharmonic coincidence assessment. The procedure is based on a previous algorithm for calculating virtual pitch [E. Terhardt, Hear. Res. 1, 155–182 (1979)], and can be regarded as a generalized and advanced version thereof.
Oceanic acoustic rays in the deep six sound channel
Authors: Miller Jack C.
Published: October 2005

A simple yet realistic model of oceanic sound-speed stratification is presented which allows the calculation of all parameters of interest describing acoustic rays. The model is based on the assumption of no surface or bottom encounters by acoustic rays and a specific choice of sound-speed profile depending only on depth. It is hoped that the model can serve as a useful zeroth-order approximation to the real ocean.
Compressional-wave velocity measurement in seabed materials by use of equipment deployed near, but above the bottom
Authors: McKay Alasdair G. , McKay P. M.
Published: October 2005

For the measurement at midaudio frequencies of the acoustic compressional wave velocity, methods are described which make use of either the refraction or the wide-angle reflection techniques in ways which do not require station keeping by the survey vessel (as when equipment is deployed on the bottom) but still minimize the adverse effect of a long water column between the sensing equipment and the seabed. Some results from areas on the Nova Scotia shelf are presented, ranging from about 3.0 km/s in a nearshore sedimentary rock sequence through 1.6 km/s on a shelf-edge sandbank to 1.25 km/s in a deep intrashelf basin.
The effective lengths for flow noise of hydrophones in a ship-towed linear array
Authors: Shashaty A. J.
Published: October 2005

To estimate the flow noise generated in a ship-towed linear array of hydrophones, the turbulent pressure fluctuations are integrated over the effective area of the hydrophone. By using a weighting process based on dipole radiation from the hose as a definition of area effectiveness, the problem of finding the effective area is reduced to an integration over the surfaces of hydrophone and hose. This effective area, expressed as a length, has been worked out for the coaxial point, line, ring, single disk, cylinder, and double disk hydrophones.
Sound transmission loss of gypsum wallboard partitions. Report ♯3. 2×4 in. wood stud partitions
Authors: Green David W. , Sherry Cameron W.
Published: October 2005

Using the data bank of the acoustics laboratory of Domtar Research, statistical equations based on surface density are derived for predicting the sound transmission class and sound transmission loss of double leaf wall partitions. The partitions are constructed using gypsum wallboard and 2×4 in. wood studs with or without glass fiber batts (R-7) in the cavity spaces. The results predicted using these equations are found to be in good agreement with results on similar assemblies tested at other laboratories. The equations are then used to illustrate the effects of surface density and method of board attachment on sound transmission loss. The STC of wood stud partitions is shown to be reduced significantly if screws directly into the studs are used for the attachment of a second layer of wallboard. The effectiveness of a glass fiber batt (R-7) cavity filler in improving STC is also shown to be highly dependent upon the method of second layer attachment. Several methods of increasing the sound transmission loss of wood stud partitions are compared.
Echo-to-reverberation (clutter) ratio for strongly bistatic systems
Authors: Stewart James L.
Published: October 2005

Expressions are derived for the echo-to-reverberation (clutter) per unit angle ratio E/R′ for the strongly bistatic case (i.e., range sum/separation, e?2) assuming the two-dimensional case of continuous channeled propagation. The E/R′ is strongly dependent on the azimuthal angle at the receiver and on the range sum but independent of the source and receiver directivities. The bistatic coverage against reverberation (clutter) is within a semicircle of the same radius as the monostatic circle of coverage in the receiver’s half-space away from the source. By source directivity which insonifies (illuminates) the region of the right bisector more strongly than the end caps, it is possible to make the echo uniform along the ellipse when E/N′ is at threshold. This extends the bistatic coverage to the whole ellipse with an area comparable with the monostatic coverage. Bistatic systems without continuous channeled propagation, e.g., in sonar at short ranges when convergence zones (CZ’s) dominate, are almost useless because the area of mutual CZ coverage by both source and receiver is insignificant. The most significant gains of multistatic over monostatic systems are the orders of magnitude lower cross-range errors and the instantaneous solutions of target course and speed.
A model of the hair cell-primary fiber complex
Authors: Ross Strange
Published: October 2005

The proposed model consists of a chain of three energy reservoirs through which energy from an infinite supply is fed to a modulator which in turn drives a firing mechanism. The modulator consists of a variable permeability p that depends on instantaneous basilar displacement a through: p = (a−A0)2 for a≳A0, and p = 0 for a?A0, where A0 is a constant. The firing mechanism consists of a Poisson generator (process) whose average output rate is proportional to energy flow through the modulator, and a classical ’’leaky integrator’’ neuronal model driven by the Poisson generator. The model, containing three fixed and eight free parameters, was examined with respect to statistical properties of spontaneous activity, relation between overall firing rate and level of stimulation, various adaptation and recovery phenomena within time ranges from a few milliseconds to several seconds, period histograms for one- and two-tone (phase-locked) stimulation, suppression of responses to one tone by subthreshold levels of another (phase-locked) tone, and neural masking. Model behavior in general was satisfactory. Deficiencies in single-cycle histograms at medium and high levels, and insufficient onset peaking in PST histograms, were attributed to the malfunctioning of one particular segment of the model, and a possible remedy was suggested.
Contralateral and ipsilateral cueing in forward masking
Authors: Moore Brian C. J. , Glasberg Brian R.
Published: October 2005

Threshold was measured for a 20-ms, 1-kHz sinusoidal signal following a narrow-band noise masker centered at 1 kHz with an overall level of 70 dB SPL. The effect of temporal uncertainty was investigated by providing a broadband, low-level noise cue, gated synchronously either with the masker intervals or the signal intervals. The cue could be either in the same ear as the signal-plus-masker, or in the opposite ear. In every case the cue produced a reduction in signal threshold, the largest reduction (about 20 dB) occurring when the cue was gated with the masker. The results indicate that in specific conditions, when the signal is similar in quality to the masker (having a similar center frequency and bandwidth), forward masking can involve a high degree of temporal uncertainty. Effects resembling ’’suppression’’ can be produced by providing a temporal cue. Adding a 1.2-kHz sinusoid at 90 dB SPL to the masker produced a 10-dB larger reduction in threshold than the noise cue. This greater effect is probably attributable to suppression of the masker by the sinusoid.
Vowel duration as a perceptual cue to postvocalic consonant voicing in young children and adults
Authors: Krause Sue Ellen
Published: October 2005

Vowel duration is a powerful acoustic cue for adults’ perception of postvocalic consonant voicing, but it has not been studied sufficiently in children. The purpose of the present work was to study the development of the use of this duration cue in 3-year-olds, 6-year-olds, and adults. The duration of the vowel was varied to construct three stimulus continua (BIP–BIB, POT–POD, BACK–BAG). The subjects, who had normal language, articulation skills, and hearing sensitivity, identified all stimuli from each of the three continua ten times. Significant developmental differences in the perceptual judgments of voicing were demonstrated. These differences were reflected in both the locus of the category boundary and the slope of the identification function.
Duration as a cue to the perception of a phrase boundary
Authors: Scott Donia R.
Published: October 2005

The presence of a phrase boundary is often marked in speech by phrase-final lengthening—a lengthening of the final stressed syllable of the phrase and a pause at the phrase boundary. The present study investigates (a) whether listeners use the feature of phrase-final lengthening to parse syntactically ambiguous sentences such as ’’Kate or Pat and Tony will come,’’ where the position of a phrase boundary after ’’Kate’’ represents one meaning, and after ’’Pat’’ another meaning, and (b) whether listeners use phrase-final lengthening directly to parse the sentence or indirectly via the effect that phrase-final lengthening has on the rhythm of the feet (the onsets of the stressed syllables) of the sentence. Four experiments are reported in which listeners are asked to judge the meaning of sentences which have been temporally manipulated so that the foot which originally did not contain the crucial phrase boundary is lengthened by (i) inserting a pause at the ’’false’’ phrase boundary [experiment I], (ii) inserting a pause and lengthening the final stressed syllable at the ’’false’’ phrase boundary [experiment II], (iii) lengthening all segments contained in the foot [experiment III], and (iv) lengthening only the conjunction within the foot [experiment IV]. The results indicate that both rhythm of the inter-stress intervals and the presence of phrase-final lengthening influence listeners’ perception of a phrase boundary, although the stress rhythm appears to be the more powerful perceptual cue.
Nearfield and farfield of pulsed acoustic radiators
Authors: Tjo/tta J. Naze , Tjo/tta S.
Published: October 2005

The acoustic field of a baffled piston source of any shape and with nonuniform velocity distribution is considered, utilizing a generalized version of the impulse response approach developed by Stepanishen [J. Acoust. Soc. Am. 49, 1629–1638 (1971)], and with emphasis in obtaining analytical results and general properties. Effects of amplitude shading and rigidity at the edge are investigated for planar sources. Asymptotic farfield expressions are obtained, which show how the shape of the pulse as well as that of the source do influence the farfield directivity. Nonplanar sources are also considered briefly.
Circumferential propagation of acoustic boundary waves in boreholes
Authors: Botter B. J. , van Arkel J.
Published: October 2005

Dispersion equations are derived to describe the circumferential propagation of elastic boundary waves along an empty and a fluid-filled borehole. These equations are solved for various Poisson ratios to yield velocity and attenuation curves as a function of the ratio of wavelength to borehole diameter. Theoretical data agree closely with data obtained in an actual borehole.
On two equations of radial motion of a spherical gas-filled bubble in a compressible liquid
Authors: Lastman G. J. , Wentzell R. A.
Published: October 2005

Two bubble models, derived from the spherically symmetric linear wave equation, are discussed. These models (second-order ordinary differential equations) differ in the way a tension-wave forcing function is incorporated into each equation. Under reasonable assumptions it is shown that the models should give similar responses. This is verified by computational examples.
Short-range acoustic transmissions through cyclonic eddies between a submerged source and receiver
Authors: Itzikowitz S. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

Consequences of eddy-induced sound-speed and current variations on acoustic propagation between a submerged source and receiver are considered using ray theory. For ranges of tens of km, those rays which exist for particular source and receiver depth and range values are determined and studied. Sound-speed and current effects on per-ray travel time and spreading loss are investigated. Changes in the former of 15 ms or more are demonstrated, depending on source and receiver locations and ray type. Then, eddy effects on total-field amplitude and phase are examined. For a cw sound signal of 400 Hz, variations of about 25 dB in amplitude and several cycles of phase are observed as source and receiver positions vary within a typical eddy. Eddy currents alone are shown to have a relatively significant effect away from the eddy center, when certain rays are present or absent, and when source and receiver change their orientations. Indeed, current effects by themselves can lead to variations of up to about 12 dB in amplitude and 0.9 cycles in phase.
The steady-state response of an internally damped double-beam system interconnected by several springs
Authors: Irie Toshihiro , Yamada Gen , Kobayashi Yukinori
Published: October 2005

The steady-state response of an internally damped double-beam system interconnected by several springs to a sinusoidally varying force is determined by the transfer matrix technique. For this purpose, the Timoshenko equations of transverse vibration of an internally damped beam are written as a coupled set of the first-order differential equations by using the transfer matrix of the beam. Once the matrix has been determined, the response of a double-beam system is obtained by the product of the transfer matrices of each beam and the point matrices at each connecting point. In this case, the elastic moduli of internally damped beams and springs are assumed to be complex quantities. The method is applied to double-beam systems interconnected by several springs of the same stiffness located at equal intervals, and the driving-point impedance, transfer impedance and force transmissibility of the systems are calculated numerically.
IHC–TM connect–disconnect in relation to sensitization and masking of a HF-tone burst by a LF tone. IV
Authors: Crane Hewitt D.
Published: October 2005

Evidence continues to accumulate that although the outer hair cells (OHCs) of the cochlea are firmly bonded to the tectorial membrane (TM), the inner hair cells (IHCs) are not. This is the fourth in a series of papers that explores how the idea of a set of disconnected hair cells that ’’impact’’ the TM is consistent with psychophysical data. The paper extends the exploration to the masking of high-frequency (HF) tone bursts by low-frequency (LF) tones and shows that the model can explain important features of these complex data.
Lip and jaw interaction during speech: Responses to perturbation of lower-lip movement prior to bilabial closure
Authors: Folkins John W. , Zimmermann Gerald N.
Published: October 2005

Electrical stimulation was used to produce unexpected, involuntary depression of the lower lip in three normal young adults. Stimulation was timed to begin 500 to 40 ms prior to voice offset in [æp] and [ip]. Upper lip, lower lip, and jaw movements were measured with a strain gauge system. Movements in 104 syllables with lower-lip stimulation were compared to the preceding normal syllable. Both the jaw and upper lip compensated for the involuntary perturbations in lower-lip movement. Compensatory movements did not occur as additional, discrete gestures following stimulation onset, but appeared as an increase in the size of closing movements. Bilabial closure was produced at the typical time (within −10 to +20 ms of voice offset) in 68% of the perturbed syllables, but it was delayed (a mean of 61 ms) in the remaining 32%. Neither the incidence nor the magnitude of this delay appeared to be related to the jaw position at stimulation onset or to the time between stimulation onset and voice offset.
Analysis and computation of the acoustic scattering by an elastic prolate spheroid obtained from the T-matrix formulation
Authors: Flax Lawrence , Dragonette Louis R. , Varadan V. K. , Varadan V. V.
Published: October 2005

The T-matrix formulation is used to compute the form function of an elastic prolate spheroid. The method allows acoustic scattering computations to be made for finite bodies at frequencies into the resonance region, and the lowest order resonance observed is, as expected, due to the excitation of a Rayleigh surface wave.
Changes in bone conduction thresholds with vibrator contact area
Authors: Queller Judith E. , Khanna Shyam M.
Published: October 2005

An experimental bone conduction vibrator was used to measure force and acceleration directly at the point of contact, the subject’s forehead. Force and acceleration at threshold were measured for six subjects over a frequency range of 250 to 6000 Hz and over a contact area range of five to one. These measurements suggest that for any test subject, the variation in force of threshold with contact area is much smaller than the corresponding variation in acceleration at threshold.
Comparison of three adaptive psychophysical procedures
Authors: Shelton Brian R. , Picardi Maria C. , Green David M.
Published: October 2005

Auditory thresholds were experimentally determined using three adaptive procedures. The procedures are a simple staircase procedure, a maximum-likelihood technique and PEST. The threshold of a sinusoid in noise (simultaneous task) and the threshold of a sinusoid in a forward masking experiment (successive task) were investigated. Number of trials per block, for the staircase and maximum-likelihood procedures, and stopping rule, for PEST, were varied in four different conditions. Nearly equal numbers of trials were obtained for each procedure. The observed variability in successive determinations of threshold was used to estimate standard errors of measurement. All three procedures produced standard errors of measurement that were nearly equal. Some slight differences among the procedures may be of interest for particular applications.