bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-language study of perception of the oral–nasal distinction
Authors: Beddor Patrice Speeter , Strange Winifred
Published: October 2005

To investigate the effect of linguistic experience on the perception of the oral–nasal distinction in vowels, Hindi and American English speakers were tested on identification and discrimination of four speechlike series generated by articulatory synthesis. In experiment I, no language-group differences were found in the discrimination of either a consonant series, [ba–ma] (a phonemic contrast in both languages), or a vowel series, [ba–bã] (phonemic only for the Hindi speakers). The vowel results were due to floor effects which obscured differences across language groups. Experiment II examined perception of two modified vowel series, one which increased the interval between members of discrimination pairs and one that extended the range of velar port opening. Cross-language differences in discrimination were found. Hindi perception of the oral–nasal distinction was categorical. English speakers’ perception of the vowel series was more continuous. They accurately discriminated differences not only across categories, but also within the oral category. These findings indicate that linguistic experience can influence listeners’ perception of vowels, but the effect is different from that shown for consonants.
Fricative–stop coarticulation: Acoustic and perceptual evidence
Authors: Repp Bruno H. , Mann Virginia A.
Published: October 2005

Eight native speakers of American English each produced ten tokens of all possible CV, FCV, and VFCV utterances with V = [a] or [u], F = [s] or [ℱ], and C = [t] or [k]. Acoustic analysis showed that the formant transition onsets following the stop consonant release were systematically influenced by the preceding fricative, although there were large individual differences. In particular, F3 and F4 tended to be higher following [s] than following [ℱ]. The coarticulatory effects were equally large in FCV (e.g., /sta/) and VFCV (e.g., /asda/) utterances; that is, they were not reduced when a syllable boundary intervened between fricative and stop. In a parallel perceptual study, the CV portions of these utterances (with release bursts removed to provoke errors) were presented to listeners for identification of the stop consonant. The pattern of place-of-articulation confusions, too, revealed coarticulatory effects due to the excised fricative context.
Measurement of pitch in speech: An implementation of Goldstein’s theory of pitch perception
Authors: Duifhuis H. , Willems L. F. , Sluyter R. J.
Published: October 2005

Recent developments in hearing theory have resulted in the rather general acceptance of the idea that the perception of pitch of complex sounds is the result of the psychological pattern recognition process. The pitch is supposedly mediated by the fundamental of the harmonic spectrum which fits the spectrum of the complex sound optimally. The problem of finding the pitch is then equivalent to finding the best harmonic match. Goldstein [J. Acoust. Soc. Am. 54, 1496–1516 (1973)] has described an objective procedure for finding the best fit for stimuli containing relatively few spectral components. He uses a maximum likelihood criterion. Application of this procedure to various data on the pitch of complex sounds yielded good results. This motivated our efforts to apply the pattern recognition theory of pitch to the problem of measuring pitch in speech. Although we were able to follow the main line of Goldstein’s procedure, some essential changes had to be made. The most important is that in our implementation not all spectral components of the complex sound have to be classified as belonging to the harmonic pattern. We introduced a harmonics sieve to determine whether components are rejected or accepted at a candidate pitch. A simple criterion, based on the components accepted and rejected, led to the decision on which candidate pitch was to be finally selected. The performance and reliability of this psychoacoustically based pitch meter were tested in a LPC-vocoder system.
Measurement of the temporal phase stability of the medium
Authors: Christoff J. T. , Loggins C. D. , Pipkin E. L.
Published: October 2005

The temporal phase stability of the medium was measured at a site used for the collection of synthetic-aperature sonar data. These measurements were conducted over a two-year time span, and were made at several different heights-above-bottom. Results obtained show that for small heights-above-bottom, the standard deviation of the phase is as small as 0.04 radians over a 20-min measurement interval. At larger heights-above-bottom, the standard deviation of the phase is much larger, getting as large as 0.31 radians over a 2-min interval for one measurement.
Exact solutions of the one-dimensional acoustic wave equations for several new velocity profiles: Transmission and reflection coefficients
Authors: Abraham P. B. , Moses H. E.
Published: October 2005

After reviewing the relationship of the acoustic equation to the Schrödinger equation, solutions of the latter are used to construct new indices of refraction [or equivalently sound velocity profiles (SVP)] for which the solutions of the acoustic equation are expressed in terms of elementary functions. The new indices of refraction can be used to form layers to model more general inhomogeneous media, just as piecewise constant slabs or other indices have been used in the past. Four of the new indices of refraction also provide especially simple closed-form examples which can be used to describe how waves are scattered in media with such indices. More general scattering problems are discussed. In particular, the notion of outgoing wave is gone into. The five indices given in the present paper are the first of several which have been obtained from Schrödinger equations with potentials for which the eigenfunctions can be found in closed form. Others will be given in later papers.
Sound propagation in a pipe containing a liquid of comparable acoustic impedance
Authors: Horne M. P. , Hansen R. J.
Published: October 2005

A detailed experimental study of sound propagation in liquids contained by pipes constructed of polymeric materials is discussed. Experiments were conducted with vertically aligned cylinders containing water ensonified at one end by a piston-driven sound source. Significant sound attenuation (as much as 60 dB) was observed in pipes made of flexible polymeric materials, the effect increasing with frequency and loss tangent. Sound propagation in more rigid polymeric pipes exhibited similar characteristics to that in metallic pipe in that negligible attenuation was observed. In this latter case, a comparison was made with recent analytical work for which excellent agreement was obtained.
Application of the WKBJ Green’s function to acoustic propagation in horizontally stratified oceans
Authors: Brown Michael G.
Published: October 2005

The Green’s function (response to an impulsive point source) for ocean acoustic propagation is found using the WKBJ seismogram technique [Chapman, Geophys. J. R. Astron. Soc. 54, 481–518 (1978)]. It is shown that the WKBJ Green’s function reduces to geometric ray theory; in the vicinity of caustics it gives the well-known Airy function range dependence of each harmonic component of the acoustic field. Arrival patterns constructed using the WKBJ Green’s function are in excellent agreement with a solution to the parabolic equation (PE) except when the source and/or receiver depth is near the turning depth of a geometric ray. Agreement with a measured arrival pattern is also found to be good.
Analysis of deep ocean sound attenuation at very low frequencies
Authors: Focke Karl C. , Mitchell S. K. , Horton C. W.
Published: October 2005

The attenuation coefficient of low-frequency, deep ocean acoustic waves is computed for various assumptions regarding the depth profile and the frequency dependence of the scatterers. The calculations are made for a realistic velocity profile by means of a perturbation technique proposed by Guthrie [Ph. D. dissertation, The University of Auckland (1975)]. It is shown that excellent agreement with experimental data is obtained when the attenuation function is independent of frequency and decreases exponentially with depth with a characteristic depth of 200 to 500 m. A surface value of 0.11 dB/km gives good agreement with the data. At frequencies below 50 Hz the attenuation in the water column is comparable to the attenuation in the sediments for the lowest order normal modes.
On the ray equivalent of a group of modes
Authors: Kamel A. , Felsen L. B.
Published: October 2005

The raylike behavior of a cluster of normal modes furnishes a useful concept for determining the interference properties of a normal-mode pressure field. In previous investigations, a selected group of modes has been heuristically smeared out into a continuum, and it has been established that the interference maximum lies along a path traversed by the ’’modal ray’’ for the central mode in the group. This approximate analysis does not quantify the corresponding amplitude behavior of the mode cluster. A rigorous basis may be provided by Poisson summation of the group of modes, which procedure incorporates systematically not only the transition to the continuum but also the effect of truncation of the mode bundle. As a result, a mode cluster may be shown to be completely equivalent, in phase and amplitude, to a ray field plus a remainder. The equivalence remains intact even in convergence zones and other transition regions where simple ray acoustics must be corrected by uniform asymptotic treatment. The remainder can be minimized by an appropriate ’’optimum’’ choice of the number of modes in the bundle, and by weighting the first and last included modes. Numerical calculations for a simple ducting environment are presented in support of these conclusions.
Effects of partial water saturation on attenuation in Massilon sandstone and Vycor porous glass
Authors: Murphy William F.
Published: October 2005

The advent of new high resolution seismic reflection and borehole sonic techniques has stimulated renewed interest in what information stress wave propagation may carry about rock properties and pore fluids in situ. We have measured extensional and shear wave velocities. Ve and Vs, and their specific attenuation, Q−1e and Q−1s, in Massilon sandstone and Vycor porous glass as a function of continuously varying partial water saturation and relative humidity. Measurements were made at frequencies from 300 Hz to 14 kHz using a resonant bar technique and from 25–400 Hz using a torsional pendulum technique. Energy loss is very sensitive to partial water saturation. In Massilon sandstone, Q−1s is maximum and greater than Q−1e only at full saturation. Q−1e rises to a strong peak at 85% water saturation. Energy loss drops significantly as the Massilon becomes ’’very dry.’’ Q−1e and Q−1s in partially saturated Massilon and Vycor are strongly frequency dependent throughout the acoustic range, exhibiting peaks between 1–10 kHz. Q−1 in dry Massilon and Vycor is independent of frequency, at least in the acoustic range. Two pore fluid mechanisms absorb energy. Viscous dissipation due to fluid flow in pores dominates in fully and partially water saturated materials. A surface capillary film mechanism dominates at low moisture contents. Nonlinear frame mechanisms such as frictional grain sliding are not signficant at normal acoustic strains, even in ’’dry’’ rocks. Compressional wave velocity and specific attenuation, Vp and Q−1p, and bulk compressional specific attenuation, Q−1k, were calculated at given frequencies. While the dependence of velocities on water saturation agrees well with a very simple explanation, there is no satisfactory theory yet available for attenuation. Vp/Vs and Q−1p/Q−1s provide sufficient information to distinguish between fully and partially water saturated Massilon sandstones, yet are insufficient to resolve the degree of partial water saturation.
On the evolution, generation, and regeneration of gas cavitation nuclei
Authors: Yount David E.
Published: October 2005

Recently a new cavitation model has been proposed in which bubble formation in aqueous media is initiated by spherical gas nuclei stabilized by surface-active membranes of varying gas permeability. By tracking the changes in nuclear radius that are caused by increases or decreases in ambient pressure, the varying-permeability model has provided precise quantitative descriptions of several bubble counting experiments carried out with supersaturated gelatin. The model has also been used to calculate diving tables and to predict levels of incidence for decompression sickness in a variety of animal species, including salmon, rats, and humans. Although the phenomena involved are in some sense dynamic, the model equations, in their present form, are essentially static and can be derived by requiring mechanical or chemical equilibrium at each setting in a rudimentary pressure schedule. In this paper, we examine the time dependence of the evolution of an individual nucleus from one equilibrium state to another, and we then investigate a statistical process by which the equilibrium size distribution of an entire population of nuclei may be generated or regenerated.
Correspondence principle in cochlear mechanics
Authors: de Boer E.
Published: October 2005

When only long waves play the most important part in the cochlea, the response can be described by a most simplified model, the one-dimensional model. When short waves are to be included, a more complex model is needed. The response then depends on the dimensionality of the model and is much harder to obtain. This applies especially to the region in the neighborhood of the point where the basilar membrane shows resonance. Both two- and three-dimensional models have been studied to assess the effects of short and long waves. The relative importance of the part played by short waves depends on the damping constant (or loss factor) δ associated with the resonance of the basilar membrane (BM). For very small δ a three-dimensional model is really necessary, it cannot be replaced by a model of lower dimensionality. When δ is small, but not too small, the three-dimensional model can be made equivalent to a two-dimensional one, provided the latter is modified in a specific manner. This paper shows why this is so and which conditions have to be met. The two-dimensional model must undergo two modifications to effect this equivalence. The first modification ensures that the model has the same long-wave behavior. In the second place, a specific additional mass (’’added mass’’) reactance should be added to Z(x). An expression for the limiting value of δ, above which this correspondence is valid, is given in the paper. A second, larger, limit is presented as well: when δ is above this limit, the responses of both the three-dimensional and the two-dimensional model are equivalent to that of an appropriately chosen one-dimensional model. In this case too, long-wave behavior must be matched and an ’’added mass’’ reactance must be included in Z(x). This holds true for the entire cochlea including the region of resonance. For both types of transition the amount of ’’added mass’’ is given.
Frequency selectivity of the monkey’s auditory system: Psychophysical tuning curves
Authors: Serafin John V. , Moody David B. , Stebbins William C.
Published: October 2005

Frequency selectivity was examined in three monkeys (Macaca nemestrina) by means of psychophysical tuning curves which were obtained under both simultaneous- and forward-masking conditions. The results showed that tuning curves obtained under the two masking conditions were qualitatively similar, sharing many of the same basic properties—sharply tuned tip segments, and greater selectivity at high frequencies than at low frequencies. As measured by Q10 dB values, however, the forward-masking tuning curves were more sharply tuned than the simultaneous-masking curves. Additionally, the two procedures resulted in different conclusions regarding how frequency selectivity varies as a function of probe frequency. The simultaneous-masking results suggested that frequency selectivity improves up to at least 16 kHz, the highest frequency tested. The results from forward masking showed frequency selectivity to be greatest in the frequency region of 1–4 kHz. The results are discussed in terms of possible differences between the procedures, and in terms of their relationship to previous studies of psychophysical tuning curves in other species.
Elastic wave scattering from surface breaking cylindrical cracks: SH waves
Authors: Varadan V. V. , Wall D. J. N. , Tsao S. J. , Varadan V. K.
Published: October 2005

The diffraction of SH waves by a crack breaking the surface of a homogeneous half-space is considered. By the use of image theory, this problem is reduced to consideration of a cavity in an infinite homogeneous space. The null field or T-matrix method is used to obtain a system of algebraic equations which are solved by a numerical scheme. The scattered field is then calculated. Numerical results are presented for the angular and frequency dependence of the scattered field from cracks of various shapes.
Empirical expression for nonlinearity parameter B/A of liquids
Authors: Endo Harumi
Published: October 2005

The nonlinearity parameter B/A is an important quantity in the study of finite amplitude sound propagation in liquids. Employing a thermodynamic expression for B/A as a polynomial of the ratio (γ) of specific heats, we empirically determined the coefficients of a quadratic equation in (γ−1) for B/A from the curve fitting of a plot of B/A vs (γ−1) by means of the least-squares method. The agreement between calculated and measured values is within the limits of variation of different measurements. If the quantity γ is obtained, it is very easy to estimate the value B/A for any liquid by the empirical expression.
Synthesis of arbitrary broadband signals for a parametric array
Authors: Singhal Sharad , Zornig John G.
Published: October 2005

An adaptive signal synthesis technique is presented that computes the waveform needed as input to a parametric array source so that the received signal has a prescribed waveform for a particular source-receiver geometry. The technique uses the Fourier transform of the digitized received signal waveform as a basis for modifying the source signal recursively until the received waveform is close to a desired shape. The method avoids completely the numerical integrations normally associated with parametric source signal design and converges to a satisfactory result within a few iterations. Thus it is fast enough to be used on line. The theory underlying the method is outlined and some examples of signals designed using the instrumentation of the Yale Hydroacoustic Communications Facility are presented.
Off-frequency listening and masker uncertainty
Authors: Glasberg Brian R. , Moore Brian C. J. , Lutfi Robert A.
Published: October 2005

This experiment was designed to determine if masker uncertainty can reduce the effects of off-frequency listening on psychophysical tuning curves (PTCs). PTCs were determined in simultaneous masking with a 1-kHz signal at 12 dB SPL, using an adaptive two-alternative forced-choice procedure. In a given run the center frequency of the narrow-band noise masker was either fixed, or varied randomly between up to eight values distributed equally above and below the signal frequency. In a control condition off-frequency listening was restricted using a ’’notched’’ broadband noise added to the fixed-frequency masker. The notch was 200 Hz wide, centered at the signal frequency, and the spectrum level in the passband was −8 dB SPL/Hz. The ’’restricted listening’’ PTCs were considerably broader than the ’’traditional’’ PTCs, but uncertainty about masker frequency had little effect. It appears that prior knowledge of masker frequency is not necessary for off-frequency listening to be effective.
Changes in plasma Angiotensin II with noise exposure and their relationship to TTS
Authors: Dengerink Harold A. , Wright John W. , Thompson Pamela , Dengerink Joan E.
Published: October 2005

Plasma concentrations of the vasoconstrictor Angiotensin II (AII) were measured in male human subjects before and after either rest or exposure to 100-dB white noise. Plasma AII concentrations decreased for subjects in the control (no noise) condition but remained high in the noise condition. In the noise exposure condition both the pre- and post-exposure AII concentrations were negatively but nonsignificantly correlated with TTS. The cardiovascular effects of noise appear to be mediated in part by AII.
A general Chebyshev complex function approximation procedure and an application to beamforming
Authors: Streit R. L. , Nuttall A. H.
Published: October 2005

A new computational technique is described for the Chebyshev, or minimax, approximation of a given complex valued function by means of linear combinations of given complex valued basis functions. The domain of definition of all functions can be any finite set whatever. Neither the basis functions nor the function approximated need satisfy any special hypotheses beyond the requirement that they be defined on a common domain. Theoretical upper and lower bounds on the accuracy of the computed Chebyshev error are derived. These bounds permit both a priori and a posteriori error assessments. Efforts to extend the method to functions whose domain of definition is a continuum are discussed. An application is presented involving ’’re-shading’’ a 50- element antenna array to minimize the effects of a 10% element failure rate, while maintaining full steering capability and mainlobe beamwidth.
Differences between spectral dependencies in auditory and phonetic temporal processing: Relevance to the perception of voicing in initial stops
Authors: Summerfield Quentin
Published: October 2005

Untrained listeners can reliably judge the temporal order of the onsets of (a) pairs of coterminous tones [forming tone-onset-time (TOT) continua], and (b) higher-frequency bandlimited noises and lower-frequency bandlimited pulse trains [forming noise-onset-time (NOT) continua], but only if the onset of the second sound lags the first by at least 15–20 ms. It has been argued that the limitation of auditory temporal-order resolution that gives rise to this threshold also underlies the distinction between voiced [b,d,g] and voiceless aspirated (ph,th,kh] syllable-initial stop consonants [which can be expressed in differences of voice-onset-time (VOT)]. The positions of boundaries between phonetic categories on VOT continua depend on the values of a variety of spectral parameters, including the onset frequency of the first formant; lowering this results in boundaries shifting to longer values of VOT. The present experiment demonstrated that analogous spectral manipulations applied to the members of TOT and NOT continua do not result in systematic shifts in the location of the simultaneity-successivity threshold. The result suggests that the role of F1 in the perception of voicing does not have a purely auditory basis, a conclusion compatible with certain developmental and cross-language studies that have demonstrated that sensitivity to F1 is acquired and language dependent. The threshold may determine ranges of VOT between which auditory contrast is heightened, and so have helped to shape the preferred phonetic forms of phonological distinctions in the world’s languages. However, other factors, such as production constraints or arbitrary processes of cultural development, appear to be required to account for the positions of voicing boundaries in particular languages.
Paired comparison judgments of relative intelligibility in noise
Authors: Studebaker Gerald A. , Bisset Jan D. , Van Ort Debra M. , Hoffnung Steven
Published: October 2005

Normal hearing and hearing impaired subjects listened alternately to continuous discourse processed by pairs of binaural hearing aids. In each case, they were asked to judge which pair of aids reproduced speech more intelligibly. Twenty-three pairs of aids competed in three elimination tournaments and one round-robin tournament. Speech discrimination tests obtained via each aid served as the criterion measure of the success of the judgments. The results were that the paired comparison procedure produced more reliable rankings than discrimination scores particularly when the difference between aids was small. Concerning validity, the normal hearing subjects identified the aids producing the best discrimination scores very well. Also, they applied confidence ratings to their judgments that were well related to the size of the performance difference between the aids. The hearing impaired subjects also performed well generally but on occasion individuals in this group chose aids that were clearly not best for them or the group.
IHC–TM connect–disconnect and efferent control. V
Authors: Crane Hewitt D.
Published: October 2005

Four previous papers in this series have explored how the idea of a set of disconnected inner hair cells (IHCs) that can ’’impact’’ the tectorial membrane (TM) is consistent with psychophysical data. This paper extends the model and explores the potential for mechanical interaction between the IHCs and outer hair cells (OHCs). In particular, it is speculated that the advantage of IHC–TM disconnect is extended dynamic range, and that movement of the OHCs and TM, under efferent control, constitutes a mechanical servo system for adjusting IHC–TM spacing along the cochlear partition to achieve this extended range.
Guided mode disappearance during upslope propagation in variable depth shallow water overlying a fluid bottom
Authors: Pierce Allan D.
Published: October 2005

The adiabatic mode theory for upslope propagation in shallow water breaks down when the depth H(x) decreases to a critical value Hc at which the mode’s phase velocity equals sound speed c2 in the underlying fluid bottom (density ρ2). Matched asymptotic expansion techniques yield the acoustic pressure in the transition region (of lateral extent c2/ωε2) in terms of Airy functions. The expansion parameter ε whose smallness justifies the required approximation is the cube root of ( ρ2/ρ1)[(c2/c1)2−1]‖H′‖. During the early approach to the critical range (taken as x = 0), the amplitude decreases within the water layer as (−x)1/2; beyond x = 0, asymptotically as x−5/2. A cylindrically spreading (as r−1/2) wave of narrow beamwidth 0.94 ε originates from the transition region (near x = 0) and propagates at angle ε with the interface obliquely downward into the bottom fluid. The derived characteristic critical-depth transition function is discussed in detail. The results are in accord with computations reported by Jensen and Kuperman [J. Acoust. Soc. Am. 67, 1564–1566 (1980)].
Acoustic slow waves and the consolidation transition
Authors: Johnson David Linton , Plona Thomas J.
Published: October 2005

We have investigated the ultrasonic properties of unconsolidated (loose) glass beads and of lightly fused (consolidated) glass beads when the pore space is saturated with water. At a frequency of 500 kHz we have observed a single compressional wave in the former whose speed is 1.79 km/s and two distinct compressional waves with speeds 2.81 km/s and 0.96 km/s in the latter. The Biot theory is shown to give an accurate description of this phenomenon. We also analyze the acoustics of low temperature He ii in packed powder superleaks; either the fast wave for unconsolidated systems or the slow wave in a highly consolidated (fused) frame may be considered to be the 4th sound mode. In all such systems, the acoustic properties can be very simply understood by considering the velocities of propagation as continuous functions of the elastic moduli of the solid skeletal frames.
Scattering of Rayleigh surface waves by edge cracks: Numerical simulation and experiment
Authors: Hirao Masahiko , Fukuoka Hidekazu , Miura Yosuke
Published: October 2005

Scattering of Rayleigh surface waves by surface edge cracks is numerically simulated in a two-dimensional geometry, using the finite-difference method and the FFT algorithm. For shallow cracks, it is revealed that the transmission coefficient decreases with normalized depth h* = hc/λ and the reflection coefficient increases with h*, where hc is the crack depth and λ the wavelength. For relatively deep cracks, these coefficients appear to be independent of h*, while the time-of-flight of the transmitted Rayleigh wave linearly increases with h*. The numerical solutions are in good agreement with the experimental observations based on the ultrasonic spectrum analysis and the time-of-flight measurements for the artificial cracks in mild-steel test pieces.
Scattering by multiple gratings of compliant tubes
Authors: Radlinski Ronald P. , Simon Murray M.
Published: October 2005

An analysis of the transmission loss for a plane wave normally incident on multiple gratings of highly eccentric compliant tubes immersed in water is developed. The symmetry of the selected geometric configurations allows a solution which parallels that of inclusions in a waveguide. The symmetric structural motion of each compliant tube is modeled as two plates connected with clamped end conditions, while the antisymmetric motion, which includes rigid body motion, is described as two plates with the end conditions of zero slope and zero transverse force. The interaction between the structural modes of vibration is discussed as a function of grating separations for several different grating geometries and compliant tube properties. In certain cases, antisymmetric tube motion is shown to severely modify the broadband performance of multiple gratings. Comparisons of the theory with experimental data are shown to be in good agreement.
Fluid/structure interaction analysis in the consideration of directivity patterns of hull-mounted transducers.
Authors: Sandman Bruce E. , Harari Azriel , Griffin James S.
Published: October 2005

For an acoustic transducer mounted on the exterior of a submerged hull structure, the effect of dynamic hull mobility upon directivity patterns is a subject of considerable interest to array design engineers. Cylindrical geometry, mounting point impedance, and structural dispersion are possible significant factors in beam pattern distortion. This analytical study utilizes a fundamental fluid/structure interaction model of submerged cylindrical shells to investigate the role of hull vibrations induced by the reactive excitation of a transducer element. It is shown that hull vibration can alter a single-element directivity pattern significantly. The model employed for this study possesses sufficient generality to consider the additional effects of hull damping, transducer isolation, and array beam forming.
Initial validation of an indirect measure of subglottal pressure during vowels
Authors: Löfqvist Anders , Carlborg Björn , Kitzing Peter
Published: October 2005

Some methods for direct measurement of subglottal pressure during speech are invasive and thus cannot be used on a routine basis. The development of noninvasive techniques is thus desirable, and a simple indirect method for measuring subglottal pressure from records of oral pressure during consonants has recently been proposed and applied to studies of glottal resistance during phonation. In order to be useful, indirect measurement procedures should be validated by comparisons with direct measurements, and the present experiment was designed for such a comparison. Miniature pressure transducers were used to obtain records of pressure below and above the glottis. Results showed nonsignificant differences and a high correlation between the direct and indirect measurements. This indirect method for measuring subglottal pressure thus appears to provide valid results.
Measurement of formant transitions in naturally produced stop consonant–vowel syllables
Authors: Kewley-Port Diane
Published: October 2005

Formant transitions have been considered important context-dependent acoustic cues to place of articulation in stop-vowel syllables. However, the bulk of earier research supporting their perceptual importance has been conducted primarily with synthetic speech stimuli. The present study examined the acoustic correlates of place of articulation in the voiced formant transitions from natural speech. Linear prediction analysis was used to provide detailed temporal and spectral measurements of the formant transitions for /b,d,g/ paired with eight vowels produced by one talker. Measurements of the transition onset and steady-state frequencies, durations, and derived formant loci for F1, F2, and F3 are reported. Analysis of these measures showed little evidence of context invariant acoustic correlates of place. When vowel context was known, most transition parameters were not reliable acoustic correlates of place except for the F2 transition and a two-dimensional representation of F2×F3 onset frequencies. The results indicated that the information contained in the formant transitions in these natural stop-vowel syllables was not sufficient to distinguish place across all the vowel contexts studied.
Acoustic modal analysis experiment
Authors: Nieter Jeffrey J. , Singh Rajendra
Published: October 2005

This paper proposes an experimental modal technique for acoustic ducts, mufflers, and resonators over the plane-wave frequency regime. Global modal properties, such as natural frequencies and modes of gas oscillation, are extracted from the coincident-quadrature response curves of measured cross-point acoustic impedances at a number of observation locations. The acoustic system is excited by a vibrating piston which is driven by an electromagnetic shaker with bandlimited binary random noise signal. The acoustic impedance is determined using the following two transducers: (i) an accelerometer attached to the piston—its signal is processed to yield volume velocity information, and (ii) a microphone traverse. Digital data acquisition and processing techniques are used to generate the necessary impedance data at a number of locations for modal analysis. In order to demonstrate the validity of our experimental technique, we have applied it to the following example cases, and obtained excellent correlation between theory and experiment: closed–closed tube, closed–open tube, and symmetrical and unsymmetrical lumped parameter systems. In this paper, we discuss the conceptual, analytical, physical, and measurement considerations of the acoustic modal analysis. We also point out some areas of further research.
Impedance-matching properties of an inhomogeneous matching layer with continuously changing acoustic impedance
Authors: Pedersen Peder C. , Tretiak Oleh , He Ping
Published: October 2005

This paper analyzes the impedance-matching properties of an inhomogeneous layer whose specific acoustic impedance varies smoothly across the layer, from the effective value of the transducer specific acoustic impedance to the value of the output medium specific acoustic impedance. In this paper we first derive the energy reflection and transmission coefficients for an inhomogeneous layer with no attenuation and constant propagation speed, and the results are presented for selected profiles. Next, the performance of an inhomogeneous matching layer with an exponential impedance profile is compared with a quarter-wavelength matching plate. Finally, the general case in which both sound speed and density of the inhomogeneous matching layer may vary is analyzed; the specific acoustic impedance profile as a function of travel time is found to be a principal factor, determining the transmission and reflection properties. The spatial functions of the acoustic parameters are determined for the case where both density and sound speed vary exponentially with travel time.
Octave discrimination: An experimental confirmation of the ’’stretched’’ subjective octave
Authors: Dobbins Peter A. , Cuddy Lola L.
Published: October 2005

Discrimination of the musical octave was measured by the method of constant stimuli with roving standards and four response categories. For each of three musically trained listners, and two of three untrained listeners, the estimated value of the subjective octave was ’’stretched’’ slightly sharper than the physical octave of 1200 cents. The magnitude of this stretch, about 20 cents on the average, replicated earlier findings obtained by the method of adjustment. A Thurstonian decision-theory model, providing iterative parametric solutions, generated an excellent fit to listeners’ psychophysical functions. The present experimental task is best described by a noncategorical model of interval perception.
The dominance region and ripple noise pitch: A test of the peripheral weighting model
Authors: Yost William A.
Published: October 2005

An estimate of the spatial curve of pitch dominance for the repetition pitch of ripple noise was measured using the pitch strength discrimination procedure. A variety of stimulus conditions were examined. The peripheral weighting model [Yost and Hill, J. Acoust. Soc. Am. 66, 400–410 (1979)] of repetition pitch assumes a relationship between the curve of pitch dominance and the shape of the psychophysical suppression or unmasking function. Ripple noise was also used to estimate the psychophysical suppression or unmasking function. The results indicate that with the estimates of the psychophysical suppression or unmasking function the peripheral weighting model can account for the general shape of the curve of pitch dominance.
A computer program for fitting a master hearing aid to the residual hearing characteristics of individual patients
Authors: Engebretson A. Maynard , Miller James D.
Published: October 2005

The electroacoustic characteristics of an experimental master hearing aid are determined by the choice of transducers and settings of 26 controls which include a preamplifier, the gains and limiting levels in each of 12 channels as well as the gain of a final power amplifier. Here, a computer program which aids in the fitting of the electroacoustic characteristics of this aid to the characteristics of a patient’s residual hearing is described. The patient’s audiologic data and the hearing-aid parameters are entered into the computer and the gain and limiting level of each channel of the hearing aid are adjusted until an appropriate fit is achieved. The results of the fitting procedure are displayed on a graphics terminal. Permanent copies of the results can be produced on a printer–plotter. Included in the results for each of 12 channels are (1) the discomfort level, most comfortable listening level, and hearing threshold of the patient, and (2) the maximum output and noise floor of the hearing aid as well as the aided speech level. This approach has simplified the problem of fitting a complicated hearing aid to a patient’s residual hearing and seems to offer attractive possibilities for fitting commercial hearing aids in the future.
A study of speech privacy in closed offices
Authors: Wyerman Barry R.
Published: October 2005

Sound attenuation was measured between two adjacent closed rooms sharing a common plenum area. Initial tests were conducted with a high STC partition between rooms. The majority of sound passing between rooms was transmitted along a path through the ceiling board and common plenum. Next, a low-cost office partition was constructed between rooms in order to measure the performance of each ceiling-partition assembly. Interzone attenuation measurements were conducted according to the PBS C.2 test method of the U.S. General Services Administration. These measurements were then compared to subjective tests for speech intelligibility from an elevated voice level in the presence of background masking sound. The results demonstrate the levels of speech privacy that can be achieved with different combinations of ceiling STC ratings, partition STC ratings, and background sound levels. Finally, ceiling systems were identified that could provide speech privacy for both open plan and closed plan offices.
Flexural waves and deflection mode shapes of periodic and disordered beams
Authors: Bansal A. S.
Published: October 2005

This paper deals with free flexural wave motion and natural deflection mode shapes of simply supported infinite uniform periodic beams consisting of repeating units that are identical finite beams having equal and unequal span lengths. Governing equations for the natural frequencies and that for the wave propagation constant have first been set up in terms of the receptances of the individual beam elements. The equations are then applied to compute the natural frequencies and deflection mode shapes together with the propagation constants for some specific disordered periodic beams that include four-span and eight-span periodic and disordered beams. Relationship between the natural frequencies of the symmetric finite repeating beam units and the bounding frequencies of the propagation and attenuation zones has been studied. The bounding frequencies are always identified with the resonance frequencies of such beams with their extreme ends either simply supported or clamped. The combinations of the natural frequencies, with which the bounding frequencies of the propagation and attenuation zones can be identified, have been pointed out. Studies of the deflection mode shapes of symmetrically and unsymmetrically disordered four-span beams have shown that the characteristic free waves in an infinite periodic system consisting of disordered repeating beams (beams of unequal span lengths) do not always decay at the natural frequencies. The conditions under which the waves at the natural frequencies of the repeating beam units decay have been studied and explained.
A lumped parameter model for the iterative analysis of cylinderlike antivibration mounts
Authors: Ianniello Carmine , Maffei Luigi
Published: October 2005

It is known that wave effects in antivibration mounts result in differences between the force transmissibility, calculated for a one-degree-of-freedom system having constant spring and dashpot parameters, and the experimentally measured one. An evaluation method which allows one to obtain the above mentioned parameters as functions of the frequency for simple rubber systems is presented. The method takes into account the high-frequency interaction between the distributed mass and elasticity which is responsible for the wave effects in the mount. Some experimental evidence about the validity of the method is given.
High-frequency normal-mode calculations in deep water
Authors: Ferla M. C. , Jensen F. B. , Kuperman W. A.
Published: October 2005

A method has been developed to perform high-frequency deep-water normal-mode calculations in the multikilohertz region in water depths of the order of 5 km. The results from this technique agree with fast field program (FFP) solutions as well as with infinite-frequency solutions in the appropriate limit. The wave-theory calculations presented therefore provide a set of test cases for future numerically more efficient approximations.
Vibration and buckling of circular plates of variable thickness
Authors: Valerga de Greco B. , Laura P. A. A.
Published: October 2005

The Ritz method and polynomial coordinate functions are used to obtain an approximate yet quite accurate and simple solution to the title problem. Results of frequency and buckling coefficients are obtained as a function of several combinations of the governing mechanical parameters.
Mode coupling due to interaction with the seabed
Authors: McDaniel Suzanne T.
Published: October 2005

A simple mode-coupling model is developed to investigate acoustic propagation in an ocean environment in which the water depth is range dependent. The model is applied to the case of a constant sloping bottom, and the results are compared with those obtained using other propagation loss models.
Acoustic propagation through a model of shallow fronts in the deep ocean
Authors: Rousseau T. H. , Siegmann W. L. , Jacobson M. J.
Published: October 2005

The effects of sound-speed variations produced by shallow (less than 300 m) deep-ocean fronts on short-range acoustic transmission between surfaced sound source and receiver are investigated using ray theory. A parametric model of such fronts, based on observational data, is constructed via sound-speed profiles which are trilinear with depth. The model is sufficiently general to permit determination of acoustical effects for fronts of varying strengths, vertical extents, and positions within the propagation range. Frontal influences on travel time and geometrical spreading loss are examined, and expressions for per-ray amplitude and phase are developed for cw transmissions with source and receiver near the surface. Then, the dependence of total-field amplitude and phase on frontal strength, vertical extent, and relative location are determined. All these frontal quantities are demonstrated to produce significant acoustical variations, such as total-field transmission-loss changes of more than 6 dB depending on frontal location. Simple and accurate approximations to both per-ray and total-field variations are presented which could predict changes in these quantities due to shallow fronts.
Parameters affecting backscattered ultrasonic leaky-Rayleigh waves from liquid–solid interfaces
Authors: de Billy Michel , Adler Laszlo , Quentin Gerard
Published: October 2005

Experiments were carried out to observe backscattered ultrasonic waves from liquid–solid interfaces. It is found that the backscattered energy is maximum at the Rayleigh angle, directly proportional to the so-called Schoch displacement (Δs) and inversely proportional to the beamwidth. This result is in qualitative agreement with the Bertoni and Tamir [Appl. Phys. 2, 157–172 (1973)] theoretical prediction for the beam distortion of the reflected field at the Rayleigh angle. It is also suggested the backscattered phenomenon enables one to measure the Rayleigh velocity at liquid–solid interfaces.
Comments on ’’Thermodynamic corrections to the velocity of propagation in a bubbly medium,’’ by E. R. Floyd [J. Acoust. Soc. Am. 70, 1748–1751 (1981)]
Authors: Cole John E.
Published: October 2005

This letter addresses an important effect omitted by the author, namely the influence of heat transfer in modifying the compressibility of the gas in a bubbly medium.
Acoustic spectroscopy
Authors: Brill D. , Gaunaurd G. C. , Überall H.
Published: October 2005

An acoustic target may be characterized by the frequency spectrum of its eigenvibrations as to size, shape, and composition. Resonance effects corresponding to acoustic excitation of the eigenvibrations, which are contained in the backscattered echoes from the target, can be used for target identification purposes. We here study the dependence of the resonance spectra of fluid targets in vacuo (or in a tenuous ambient fluid) on target shape, in order to illustrate this approach, presenting the eigenfrequency spectra in the form of ’’level schemes’’ as in atomic spectroscopy, and hereby introducing the concept of ’’acoustic spectroscopy.’’
Acoustic propagation in rigid ducts with blockage
Authors: El-Raheb Michael , Wagner Paul
Published: October 2005

The effect of blockage on the acoustic propagation in finite cylindrical cavities is studied. The shift in acoustic resonances corresponding to longitudinal and transverse standing waves is determined from a simplified one-dimensional plane-wave theory and compared to a more precise three-dimensional analysis based on a Green’s function surface element method adopted to axisymmetric geometries. One-dimensional theory is qualitatively acceptable even for large blockage while details of the acoustic field are revealed only by the three-dimensional analysis.