bluuebunny/crossref_metadata_2025 huggingface dataset:
Reacquisition of contrastive stress in an adventitiously deaf speaker using a single-channel cochlear implant
Authors: Leder Steven B. , Spitzer Jaclyn B. , Milner Paul , Flevaris-Phillips Carole , Richardson Frederick , Kirchner J. Cameron
Published: October 2005

Acoustic correlates of contrastive stress, i.e., fundamental frequency (F0), duration, and intensity, and listener perceptions of stress, were investigated in a profoundly deaf subject (RS) pre/post single-channel cochlear implant and longitudinally, and compared to the overall patterns of age-peer profoundly deaf (JM) and normally hearing subjects (DL). The stimuli were a group of general American English words in which a change of function from noun to verb is associated with a shift of stress from initial to final syllable, e.g., CON′trast versus conTRAST′. Precochlear implant, RS was unable to produce contrastive stress correctly. Hearing one day post-stimulation resulted in significantly higher F0 for initial and final stressed versus unstressed syllables. Four months post-stimulation, RS maintained significantly higher F0 on stressed syllables, as well as generalization of significantly increased intensity and longer syllable duration differences for all stressed versus unstressed syllables. Perceptually, listeners judged RS’s contrastive stress placement as incorrect precochlear implant and as always correct post-cochlear implant. JM’s contrastive stress was judged as 96% correct, and DL’s contrastive stress placement was 100% correct. It was concluded that RS reacquired all acoustic correlates needed for appropriate differentiation of contrastive stress with longitudinal use of the cochlear implant.
A timing model for word-initial CV syllables in Modern Greek
Authors: Fourakis Marios
Published: October 2005

Measurements of the temporal characteristics of word-initial stressed syllables in CV CV-type words in Modern Greek showed that the timing of the initial consonant in terms of its closure duration and voice onset time (VOT) is dependent on place and manner of articulation. This is contrary to recent accounts of word-initial voiceless consonants in English which propose that closure and VOT together comprise a voiceless interval independent of place and manner of articulation. The results also contribute to the development of a timing model for Modern Greek which generates closure, VOT, and vowel durations for word-initial, stressed CV syllables. The model is made up of a series of rules operating in an ordered fashion on a given word duration to derive first a stressed syllable duration and then all intrasyllabic acoustic intervals.
Perception of the [m]–[n] distinction in CV syllables
Authors: Repp Bruno H.
Published: October 2005

The contribution of the nasal murmur and the vocalic formant transitions to perception of the [m]–[n] distinction in utterance-initial position preceding [i,a,u] was investigated, extending the recent work of Kurowski and Blumstein [J. Acoust. Soc. Am. 76, 383–390 (1984)]. A variety of waveform-editing procedures were applied to syllables produced by six different talkers. Listeners’ judgments of the edited stimuli confirmed that the nasal murmur makes a significant contribution to place of articulation perception. Murmur and transition information appeared to be integrated at a genuinely perceptual, not an abstract cognitive, level. This was particularly evident in [−i] context, where only the simultaneous presence of murmur and transition components permitted accurate place of articulation identification. The perceptual information seemed to be purely relational in this case. It also seemed to be context specific, since the spectral change from the murmur to the vowel onset did not follow an invariant pattern across front and back vowels.
Partial groups in the bell sound
Authors: Lehr André
Published: October 2005

The flexural vibrations of a bell can be classified into different groups, each group consisting of partials with an equal number of nodal circles in about the same position on the bell wall. A bell also shows extensional vibrations which seldom occur at frequencies below the nominal, except in carillon bells with a thick wall. These vibrations are sometimes important for the timbre of the bell in spite of the fact that their amplitudes are usually small because extensional vibrations have an antinode at the head of the bell. Research into the dependence of partial frequencies on wall thickness did not support the linear function predicted by the elementary bending theory. Measurements on especially designed bells that differed only in wall thickness were more consistent with an extensive theory of, e.g., a ring. Partials were found to shift in groups, not individually, as a function of increasing wall thickness. From a musical viewpoint, the group of flexural partials with a nodal circle at the waist of the bell is important in forming the bell’s primary and secondary strike notes. The bell’s timbre will depend on relative partial amplitudes, the partial intervals within groups, and the position of partial groups with respect to one another.
Vibration characteristics of two buoy bells
Authors: Kuntz Herbert L. , Hixson Elmer L.
Published: October 2005

Various methods have been used to study the complex vibrations of bells; most methods employ striking the bell. In this paper, sinusoidal excitation of two buoy bells (38.5 and 102 kg) and measurement of the dynamic mass (force/acceleration) at the strike point are applied to determining the resonances. Transfer functions between two locations on the bell surface are used to measure mode shapes. Impact excitation is used to substantiate the impedance results and to measure the decay times of the modes of vibration. Resonance frequency predictions are made for a third, untested buoy bell.
Acoustic radiation characteristics of two buoy bells
Authors: Kuntz Herbert L.
Published: October 2005

Various methods have been used to study the complex acoustic radiation of bells; most methods employ striking the bell. In this paper, sinusoidal excitation of two buoy bells (38.6 and 102 kg) and measurement of the radiated acoustic pressure to the driving point force transfer function (p/F) are applied to determining the directivity patterns and the geometric nearfield size for several partials of each bell. Impact excitation is used to measure the temporal characteristics of the sound. Analysis indicates that the first partial directivity pattern of a bell may be predicted through the use of a tesseral quadrupole. The quadrupole has the same diameter as the bell rim.
Diffraction of Rayleigh waves in a half-space. II. Inclined edge crack
Authors: Kinra Vikram K. , Vu Bien Q.
Published: October 2005

This paper is concerned with the diffraction of a Rayleigh surface wave by an edge crack included at an arbitrary angle to the free surface of a half-space. The corresponding problem for a normal edge crack was studied in [B. Q. Vu and V. K. Kinra, J. Acoust. Soc. Am. 77, 1425–1430 (1985)]. The scattered field was measured on the free surface both in the vicinity of the crack and far away from it. The nearfield possesses a number of interesting features which can be used to characterize an inclined crack. The farfield transmission and reflection coefficients, AT and AR, respectively, were measured under both the steady time-harmonic motion (tone burst) and the transient motion (spectroscopy) of the half-space. All three regions of interest were studied: wavelengths large, equal, and small compared to the crack lengths. As expected, in the short-wavelength limit, AR asymptotically reaches its frequency-independent limit which is the reflection coefficient of an infinite wedge. This limit was found to agree very well with the earlier results by Viktorov for a wedge [I. A. Viktorov, Rayleigh Waves and Lamb Waves—Physical Theory and Application (Plenum, New York, 1964)]. The transmission coefficient exhibits an oscillatory dependence on frequency; this is attributed to a resonance between the crack tip and the free surface. The spacing between the peaks of AT was found to satisfy the following simple kinematic condition: wavelength equals twice the crack length. Furthermore, AT was found to be measurably identical for two complementary cracks of inclination θ and π−θ, where θ is measured from the free surface.
Sound scattering from a thin rod in a viscous medium
Authors: Lin Wen H. , Raptis A. C.
Published: October 2005

Sound waves incident on a thin elastic rod whose radius is smaller than the wavelength of the incident sound induce flexural and uniform compressional oscillations in the rod. These elastic oscillations, in turn, radiate sound waves into the fluid medium and affect the scattered waves. This paper deals with an analytic study on sound scattering by, and acoustoelastic vibrations of, a thin elastic unbound rod in a viscous fluid. The shear viscosity of the fluid is considered in the solutions to boundary value problems concerning the sound scattering and the elastic response of the rod. Results show that the scattered compressional waves consist of the rigid-rod scattering of compressional waves, monopolar waves due to the uniform pulsating of the rod, and dipolar waves due to the flexural vibration of the rod. The scattered viscous waves consist of the rigid-rod scattering of viscous waves and dipolar waves due to the flexural vibration of the rod. Acoustic resonances occur when the effective inertia force of the rod balances the stiffness force of the rod. The fluid viscosity and the scattering of sound give rise to damping effects for the rod vibrations and signficantly affect the acoustic resonances.
Synthesis of backscattering from an elastic sphere using the Sommerfeld–Watson transformation and giving a Fabry–Perot analysis of resonances
Authors: Williams Kevin L. , Marston Philip L.
Published: October 2005

The Sommerfeld–Watson transformation (SWT) was recently applied to the acoustic backscattering from elastic spheres in water having ka≫1 [K. L. Williams and P. L. Marston, J. Acoust. Soc. Am. 78, 1093–1102 (1985)]. Expressions for the scattering due to each class of elastic surface wave (e.g., the Rayleigh wave) were interpreted in terms of contributions from repeated circumnavigations. In the present paper, these expressions are summed in closed form as in the analysis of Fabry–Perot resonators. The form function is synthesized by adding this sum to the specular reflection. The procedure is confirmed by comparison with the exact form function f for a tungsten carbide sphere in the range 10≤ka≤80. In this case, the interference of the specular and Rayleigh contributions produces the underlying structure in ‖f(ka)‖, while the whispering gallery wave resonances produce a finer superposed structure. Phase shifts and coupling coefficients are identified which affect the signatures in ‖f(ka)‖ of the Rayleigh wave resonances.
Acoustic attenuation in fluid-saturated porous cylinders at low frequencies
Authors: Dunn Keh-Jim
Published: October 2005

Laboratory measurements on the elastic moduli and the acoustic attenuation of fluid-saturated porous rock cylinders are frequently affected by the boundary conditions of the rock sample, i.e., whether the curved surface of the cylindrical sample is exposed to air or properly sealed. In this paper, the analytical solutions of these problems for the extensional, torsional, and flexural modes are derived, and several numerical examples are computed. It was found that there exists an ‘‘artificial’’ attenuation caused by the open-pore boundary condition, whose relaxation frequency, in the case of extensional mode, is directly proportional to the permeability of the rock and inversely proportional to the viscosity of the pore fluid and the square of the sample radius. This attenuation exists in both the extensional and the flexural modes but not in the torsional mode.
On the mode-splitting of Love waves in a rough layer
Authors: Lerche I.
Published: October 2005

Using the technique of mean-field renormalization, it is shown that the general effect of surface roughness on Love waves is to cause not only a splitting of the mode frequency but also an effective attenuation because of multiple scattering from the rough surface. The precise amounts of splitting and attenuation are shown to be dependent on the power spectrum of the surface roughness as well as on the normal mode. The calculation is restricted to the two-dimensional problem where the roughness varies in one spatial direction only so that coupling of the Love modes to P–SV waves is strictly forbidden. For surface roughness, of rms amplitude 〈 f 2〉1/2, occurring on a scale that is long when compared to the Love mode wavelength, both the frequency splitting and effective attenuation are of fractional order ω〈 f 2〉1/2(s21−s22)12/2, where ω is the angular frequency and s1 and s2 are the slowness on either side of the rough boundary. For a surface roughness dominating the evaluation of certain basic integrals occurring in the mean-field dispersion relation, it is shown that the modes couple nonlinearly to the rough fluctuations so that both resonant scattering of the modes amongst themselves, as well as nonresonant scattering to ‘‘background’’ oscillations, takes place. These analytic calculations have been done to both illustrate the broad range of diverse phenomena that can arise as well as to provide formulas for later comparison against numerical experiments and synthetic seismograms.
The existence of caustics and cusps in a rigorous ray tracing representation
Authors: Floyd Edward R.
Published: October 2005

With rigorous ray tracing, caustics and their associated cusps in addition to those of classical ray tracing are encountered. These additional caustics are associated with classical (WKB) vertex points. Rigorous ray tracing also confirms those caustics that exist under a classical ray tracing representation, albeit both displaced from the classical locations into the classical shadow zone and perhaps deformed with additional cusps.
Applications of multifold Kirchhoff–Helmholtz path integrals to sound propagation in the ocean. Part I: Theory
Authors: Frazer L. Neil
Published: October 2005

Kirchhoff–Helmholtz theory is used to derive a generalized ray theory, called the multifold path integral (MFPI) method, that enables the calculation of frequency-dependent ray theoretical amplitudes at caustics and shadows where ordinary ray theory (geometrical acoustics) fails. The method is then applied to some problems of acoustic propagation in an ocean whose sound-speed profile, bathymetry, and bottom characteristics are all range dependent. Specifically, considered are: (a) rays with multiple bounces between the surface and a bottom that is rough on a scale much larger than a wavelength of the signal; (b) rays in a sound-speed channel whose axis height varies with range; and (c) rays around an obstacle such as a seamount. Modeling examples will be presented in a subsequent paper but included here is a discussion of various methods for evaluating the multifold integrals.
Flat-spectrum speech
Authors: Schroeder M. R. , Strube H. W.
Published: October 2005

Flat-spectrum stimuli, consisting of many equal-amplitude harmonics, produce timbre sensations that can depend strongly on the phase angles of the individual harmonics. For fundamental frequencies in the human pitch range, many realizable timbres have vowel-like perceptual qualities. This observation suggests the possibility of constructing intelligible voiced speech signals that have flat-amplitude spectra. This paper describes a successful experiment of creating several different diphthongs by judicious choice of the phase angles of a flat-spectrum waveform. A possible explanation of the observed vowel timbres lies in the dependence of the short-time amplitude spectra on phase changes.
Some observations on the development of anticipatory coarticulation
Authors: Repp Bruno H.
Published: October 2005

The influence of vocalic context on various temporal and spectral properties of preceding acoustic segments was investigated in utterances containing [E♯CV] sequences produced by two girls aged 4;8 and 9;5 years and by their father. The younger (but not the older) child’s speech showed a systematic lowering of [s] noise and [th] release burst spectra before [u] as compared to [i] and [æ]. The older child’s speech, on the other hand, showed an orderly relationship of the second-formant frequency in [E] to the transconsonantal vowel. Both children tended to produce longer [s] noises and voice onset times as well as higher second-formant peaks at constriction noise offset before [i] than before [u] and [æ]. All effects except the first were shown by the adult who, in addition, produced first-formant frequencies in [E] that anticipated the transconsonantal vowel. These observations suggest that different forms of anticipatory coarticulation may have different causes and may follow different developmental patterns. A strategy for future research is suggested.
Frequency selectivity of single cochlear-nerve fibers based on the temporal response pattern to two-tone signals
Authors: Greenberg Steven , Geisler C. Daniel , Deng Li
Published: October 2005

The physiological basis of auditory frequency selectivity was investigated by recording the temporal response patterns of single cochlear-nerve fibers in the cat. The characteristic frequency and sharpness of tuning was determined for low-frequency cochlear-nerve fibers with two-tone signals whose frequency components were of equal amplitude and starting phase. The measures were compared with those obtained with sinusoidal signals. The two-tone characteristic frequency (2TCF) is defined as the arithmetic-center frequency at which the fiber is synchronized to both signal frequencies in equal measure.

The 2TCF closely corresponds to the characteristic frequency as determined by the frequency threshold curve. Moreover, the 2TCF changes relatively little (2%–12%) over a 60-dB intensity range. The 2TCF generally shifts upward with increasing intensity for cochlear-nerve fibers tuned to frequencies below 1 kHz and shifts downward as a function of intensity for units with characteristic frequencies (CF’s) above 1 kHz. The shifts in the 2TCF are considerably smaller than those observed with sinusoidal signals. Filter functions were derived from the synchronization pattern to the two-tone signal by varying the frequency of one of the components over the fiber’s response area while maintaining the other component at the 2TCF. The frequency selectivity of the two-tone filter function was determined by dividing the vector strength to the variable frequency signal by the vector strength to the CF tone. The filter function was measured 10 dB down from the peak (2T Q10 dB) and compared with the Q10 dB of the frequency threshold curve. The correlation between the two measures of frequency selectivity was 0.72. The 2T Q10 dB does change as a function of intensity. The magnitude and direction of the change is dependent on the sharpness of tuning at low and moderate sound-pressure levels (SPL’s). The selectivity of the more sharply tuned fibers (2T Q10 dB>3) diminishes at intensities above 60 dB SPL. However, the broadening of selectivity is relatively small in comparison to discharge rate-based measures of selectivity. The selectivity of the more broadly tuned units remains unchanged or improves slightly at similar intensity levels. The present data indicate that the frequency selectivity and tuning of low-frequency cochlear-nerve fibers are relatively stable over a 60-dB range of SPL’s when measured in terms of their temporal discharge properties.
Critical modulation frequency based on detection of AM versus FM tones
Authors: Schorer E.
Published: October 2005

The ratios between the modulation index (η) for just noticeable FM of a sinusoidally modulated pure tone and the degree of modulation (m) for just noticeable AM at the same carrier and the same modulation frequency were measured at carrier frequencies of 0.125, 0.25, 0.5, 1, 2, 4, and 8 kHz. Signal levels were 20 dB SL and 50 dB SPL or 80 dB SPL. At low modulation frequencies, for example, 8 Hz, AM and FM elicit very different auditory sensations (i.e., a fluctuation in loudness or pitch, respectively). In this case, η and m show different values for just noticeable modulation. Since both stimuli have almost equal amplitude spectra if η equals m ( m<0.3), the difference in detection thresholds reflects differences in the phase relation between carrier and sidebands in AM and FM. With increasing modulation frequency, the η–m ratio decreases and reaches unity at a modulation frequency called the ‘‘critical modulation frequency’’ (CMF). At modulation frequencies above the CMF, the same modulation thresholds are obtained for AM and FM. Therefore, it can be concluded that the difference in phase between the two types of stimuli is not perceived in this range. At center frequencies below 1 kHz, where phase errors caused by headphones and ear canal presumably are small, the CMF is useful in estimating critical bandwidth.
Reactions of bowhead whales, B
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s, to seismic exploration in the Canadian Beaufort Sea
Authors: Richardson W. John , Würsig Bernd , Greene Charles R.
Published: October 2005

The behavioral reactions of bowhead whales to (1) distant seismic vessels not under our control, (2) a controlled approach by a seismic vessel, and (3) controlled tests with a single airgun were observed. (1) On 21 occasions in the summers of 1980–84, general activities of bowheads exposed to pulses of underwater noise (107–158 dB re: 1 μPa) from seismic vessels 6–99 km away were observed. Activities were indistinguishable from those without seismic noise; there was no detectable avoidance. Hints of subtle changes in surfacing, respiration, and diving behavior were unconfirmed, but were consistent with reactions to stronger noise pulses from closer seismic boats. (2) In a test with a full-scale seismic boat (30 airguns totaling 47 l, source level 248 dB re: 1 μPa, closest point of approach=1 1/2 km), bowheads began to orient away when the airgun array began to fire 7 1/2 km away. However, some whales continued apparent near-bottom feeding until the vessel was 3 km away. Whales were displaced by about 2 km. Reactions were not much stronger than those to any conventional vessel. (3) Tests with one 0.66-l airgun showed that some bowheads move away from sources of strong seismic impulses even in the absence of boat noise, and that bowheads can detect the direction from which seismic impulses arrive. In general, bowheads exhibit avoidance reactions when they receive seismic pulses stronger than about 160 dB re: 1 μPa. Evidence of reactions to lower received levels remains inconclusive.
Measurement of acoustic impedance using a capillary: An attempt to achieve optimization
Authors: Kergomard Jean , Caussé René
Published: October 2005

The choice of the dimensions of capillary tubes used for acoustic impedance measurements (with applications to wind musical instruments or materials) depends on the frequency and impedance ranges. It is shown that there is an optimum range for the ratio of the length of the tube to its area, in order to have a flat amplitude response over a wide range of frequency. Several shapes of capillaries, in particular a narrow slit with arbitrary shape, such as a hexagon inscribed in a circle, using an approximate theory of viscothermal effect are studied. The upper limit of frequency does not depend on the shape, but only on the length of the capillary. Therefore, the choice of the dimensions starts with the frequency range, and our study allows one to deduce successively the length, the transverse dimension related to the width of the slit, and finally, from the impedance range, the transverse dimension related to the number of capillaries.
Specific acoustic impedance measurement by a protruding tube method
Authors: Dunlop John I.
Published: October 2005

A method is described for measuring the acoustic parameters (structure constant and damping constant) of porous absorbing materials using an open-ended tube which is inserted into the test material. The specific acoustic impedance at the face of the sample in the tube is measured and the required acoustic parameters are determined from these measurements. The results obtained from measurement on two flexible foams agree with previously determined values. The technique offers increased precision over the open flanged tube method but its range of application is more restricted.
Comment on ‘‘Transfer function method of measuring acoustic intensity in a duct system with flow’’ [J. Acoust. Soc. Am. 6
8, 1570–1577 (1980)]
Authors: Vasudevan M. S. , Fahy F. J.
Published: October 2005

An apparent error has been discovered in the published version of the principal equation of Chung and Blaser’s important paper on the measurement of sound intensity in a flowing fluid [J. Acoust. Soc. Am. 68, 1570–1577 (1980)]. This equation has been quoted in subsequent publications by other authors. Numerical analyses which have been made to investigate its practical significance indicate that application of the incorrect form of the equation can lead to very severe errors, especially in highly reactive fields.
Spectral analysis of sung vowels. III. Characteristics of singers and modes of singing
Authors: Bloothooft Gerrit , Plomp Reinier
Published: October 2005

The 1/3-oct spectra of nine different vowels, sung by 14 professional male and female singers in nine different modes of singing, were analyzed to reveal spectral characteristics of individual singers and modes of singing. The main spectral differences between singers could be described in two dimensions characterizing, respectively, differences among male and among female singers. Spectral characteristics of these dimensions suggested that interindividual differences among males, like the average difference between males and females, arise mainly from differences in vocal tract dimensions, whereas interindividual differences among females may have a glottal basis. The spectral characteristics of the modes of singing could be represented for each vowel in two dimensions. Differences among the soft (pianissimo), light, neutral, free, straight, extra vibrato, and loud (fortissimo) modes were mainly due to the spectral effect of vocal effort, which constituted a very dominant first spectral dimension. This dimension essentially reflected the slope of the spectrum. The second dimension mainly described the spectral differences between the dark and pressed modes of singing. A possible explanation of the results in terms of glottal and supraglottal morphological variation is discussed.
Effect of spherical scatterers on the driving-point impedance and directivity pattern of a sonar transducer at an air–water surface
Authors: Karim Mohd Mustaman A. , Stumpf Folden B.
Published: October 2005

Measurements of the driving-point impedance loop and directivity pattern of a small magnetostrictive-stack transducer were made for the transducer at an air–water surface in the presence of spherical scatterers in the water. The scatterers, a hollow sphere and a hard sphere, were mounted on the transducer’s radiation axis in the water below at depths of λ/4, λ/2, and λ. Significant effects were found.
Impedance formulation of the fast field program for acoustic wave propagation in the atmosphere
Authors: Lee S. W. , Bong N. , Richards W. F. , Raspet Richard
Published: October 2005

In an earlier paper, the present authors’ work in adapting the fast field program (FFP) formulation to atmospheric propagation above a complex impedance boundary was described. It was found that numerical overflow problems for high frequencies and multiple layers limited the utility of the FFP in solving atmospheric problems. In this paper is a description of a new formulation which eliminates the overflow problems inherent in the earlier formulation. The results of these two formulations are compared for a test case and the superiority of the new formulation is demonstrated. Results of the FFP2 for a simple atmospheric profile are compared with field measurements and the applicability discussed.
Coherence propagation and geometric acoustics
Authors: Berman David H. , McCoy John J.
Published: October 2005

In this work, the method of propagating the mutual coherence function through a deterministic environment using geometric acoustic Green’s functions is shown. It is also demonstrated how WKB Green’s functions for the acoustic field result in the locally quadratic approximation for the coherence function. Next, it is shown that an exact channel function can be constructed which smooths, or filters, the locally quadratic approximation and results in the exact mutual coherence function in a range-independent environment. Calculating the coherence function with WKB Green’s functions reveals multipath interference which is not properly accounted for by the locally quadratic radiative transport equation. When multipaths coalesce to form a smooth caustic, extensions of the locally quadratic transport equation give correct results only because interfering rays sample only a limited part of space. In the case of smooth caustics, it is shown that the coherence function as calculated from geometric acoustics agrees in detail with recently derived results for the coherence function which are based on the extended transport equation.
Sensitivity of a passive tracking algorithm to input variations
Authors: Bilazarian P. , Siegmann W. L. , Jacobson M. J.
Published: October 2005

The sensitivity of a passive horizontal-tracking algorithm to variations in input measurements is investigated. The algorithm determines estimates for depth, range, bearing, horizontal speed, course, and frequency for a cw acoustic source moving with constant velocity at fixed depth. The receiver is a horizontal linear array towed at a constant depth. Both source and receiver move in the upper portion of a deep ocean and are separated by a relatively short range. Dominant acoustic signals are presumed to arrive along two upper-ocean ray paths. The algorithm uses a new combination of input quantities, including multipath information, Doppler frequency shifts, and array directional measurements. Procedures are developed for analyzing effects of input-measurement errors on source localization. The robustness of the algorithm to small variations in acoustic measurements and environmental parameters is demonstrated for a variety of source–receiver configurations. Variance estimates of position and motion are obtained in terms of input-measurement variances. Bounds on tracker performance are developed for measurements that are affected by noise. Results from the several types of analyses corroborate the sensitivity characteristics of the algorithm.
Effect of roughness on subsonic flexural waves in a thin plate overlying a compressible fluid
Authors: Tolstoy I.
Published: October 2005

The interaction between a thin plate (kH≲1, k being the wavenumber and H the plate thickness) and a compressible fluid half-space through a slightly rough boundary may be represented by the standard thin plate equations plus a smoothed boundary condition for the displacement of the fluid normal to the plate. This replaces the rough boundary by a fictitious smooth plane at which the relation ∂φs/∂z =ηφ1 must be obeyed, where φs is the perturbation of the smooth boundary solution due to roughness, φ1 is the total acoustic potential in the fluid at the smooth plane z=0, and η is a constant which, for isotropic roughness or for corrugations, is defined by two scatter parameters. This condition is isomorphic to those used for other types of rough interfaces [I. Tolstoy, J. Acoust. Soc. Am. 75, 1–22 (1984)]—the main difference residing in the numerical values of the parameters. The most important effects are connected with the flexural modes of the plate. Here, the roughness causes energy losses into incoherent acoustic scatter and introduces an important level of attenuation. Harmonic point source solutions are obtained for several types of interface roughness, showing that, for moderate and large ranges r (kr≳102), this effect introduces an effective cutoff frequency for κh≲1, κ being the horizontal wavenumber of the flexural waves and h the spacing between the bosses (or corrugations of the roughness model). The effect of the roughness on the flexural wave dispersion is of the order of several percent, and should be measurable for plates of relatively low flexural rigidity.
Frequency and angle spreads of acoustic signals reflecting from a fixed rough boundary
Authors: Zabal Xavier , Brill Michael H. , Collins Joseph L.
Published: October 2005

A simple geometric-acoustic model (used previously to predict time spreads of reflecting signals) is slightly modified and extended to predict frequency and angle spreads, which can be used to predict coherence losses to sonar systems. In that model, the expected energy received from a boundary facet (via reflection) is computed as a function of the x and y coordinates of the facet. A ray arriving from any facet has a well-defined travel time, relative-frequency shift (for a given source and receiver motion), polar arrival angle, and azimuthal arrival angle. The frequency-spread function is defined as the histogram of expected received energies as a function of Q=( f−f0)/ f0, where f0 and f are, respectively, sent and received frequencies of a transmitted cw signal. The angle-spread function is similarly defined for the polar and azimuthal angles. The angle-spread function shows the well-known ‘‘shifting toward the horizon’’ of the reflected image of a source as the reflecting surface gets rougher. An analogous effect occurs for frequency spread. Because the horizon limits Doppler and angle spread, increased roughness sometimes narrows the spread functions instead of broadening them. Coherence-loss computations are performed using a plane-wave approximation local to the receiver.
Time-domain first-Born approximations to backscattering from cylinders
Authors: Lee D. A. , Warhola G. T.
Published: October 2005

Time-domain first-Born approximations to backscattering of observed incident elastodynamic pulses by isolated cylindrical voids or inclusions are produced with rapid and computationally inexpensive procedures using polynomial splines represented as a series of basic splines. The approximations are in good qualitative agreement, and fair quantitative agreement, with observed backscatter.
Development of auditory-evoked potentials in the cat. I. Onset of response and development of sensitivity
Authors: Walsh Edward J. , McGee JoAnn , Javel Eric
Published: October 2005

Auditory-evoked potentials, originating from the brain stem and the forebrain, were studied in 30 unanesthetized kittens during the first 3 months of postnatal life, and from a smaller set of animals before and after surgical exposure of their tympanic membranes. In intact animals, responses to 135-dB peak SPL clicks were first reliably discernible on the seventh postnatal day; when stimuli were presented directly to the exposed tympanic membrane, responses were observed several days earlier. Responses progressed through three stages during maturation: an early period of gross insensitivity during which responses are evoked only by high-intensity stimuli and whose response thresholds remain essentially constant (week 1); a middle period characterized by rapid acquisition of sensitivity to near-adult values (week 2); and a late period during which adult thresholds and latencies are acquired. A sequential stage model of threshold maturation is proposed, in which thresholds decline linearly during stage two and exponentially during stage three. It is hypothesized that mechanical reorganization of the cochlea during the first 2 to 3 postnatal weeks and development of the stria vascularis are primarily responsible for the linear stage, and that neural factors primarily underlie the exponential stage and account for the gradual acquisition of adult thresholds. Rates of maturation for brain stem responses are frequency dependent, with responses to high frequencies achieving adult thresholds earlier than those to low frequencies.
Development of auditory-evoked potentials in the cat. III. Wave amplitudes
Authors: Walsh Edward J. , McGee JoAnn , Javel Eric
Published: October 2005

Amplitudes of auditory-evoked brain stem response (ABR) and late-occurring auditory-evoked potential (AER) components were recorded from kittens between birth and 90 postnatal days. All ABR and AER wave amplitudes increased during the first postnatal month. Wave amplitudes exhibited nonmonotonic growth with increasing age, attaining a maximum at 40–60 days of age, after which amplitudes decreased. Amplitudes of waves originating in the auditory nerve matured somewhat faster than waves originating in the brain stem and forebrain, and the order in which waves reached maturity was roughly the reverse order of the latencies of their peaks. Input–output curves for ABR and AER waves displayed nonmonotonic behavior that varied as a function of postnatal age. Wave amplitudes recorded from adult cats increased between threshold and 70 dB SPL, then decreased between 70 and 100 dB SPL, and rapidly increased above 100 dB SPL. The intensity corresponding to the change from increasing to decreasing amplitudes was higher for younger animals and achieved adult values during the first postnatal month.
Absolute intensity discrimination using two responses
Authors: Green David M. , von Gierke Susanne M. , Hanna Thomas E.
Published: October 2005

The observer was asked to judge whether a comparison sound was more or less intense than a standard sound of 60 dB SPL. The sounds were broadband noises of 100-ms duration. The independent variables were the range of intensities used in the set of comparison sounds and the presence or absence of feedback. The main dependent variable was the variability of such judgments, which was measured from the psychometric function. The variability, measured in terms of the Weber function, increased from about 1.5 to 4 dB when the stimulus range changed from 10 to 60 dB. Increases in stimulus range increased the variability of the binary judgments in this task, as they had in previous experiments where multiple responses were required. Feedback improved performance primarily at the largest ranges. Only a small fraction of these changes in variability stems from sequential effects.
Age categorization of high-frequency auditory threshold data
Authors: Schechter M. A. , Fausti S. A. , Rappaport B. Z. , Frey R. H.
Published: October 2005

This article presents high-frequency (8- to 20-kHz) auditory threshold measurements for 157 subjects with normal conventional hearing, ranging in age from 6–30 years. Normative descriptive data are provided in five semidecade age categories. Intra-age category mean and variance values for threshold sensitivity and interaural threshold differences are included. Generally, the data are consistent with the expectation of a gradual diminution of high-frequency sensitivity through the adolescent and early adult years. Several unresolved issues related to high-frequency normative data and clinical applicability of high-frequency threshold measurements are discussed.
The role of frequency versus informational cues in uncertain frequency detection
Authors: Howard James H. , O’Toole Alice J. , Rice Susan E.
Published: October 2005

The role of frequency and informational cues in the detection of tones of uncertain frequency was investigated using the probe-signal method [G. Z. Greenberg and W. D. Larkin, J. Acoust. Soc. Am. 44, 1513–1523 (1968)] with auditory and visual test patterns. Patterns consisted of a sequence of events, either tones or visual stimuli, preceding the tone to be detected. Both frequency and informational cues were available in the auditory patterns, whereas only informational cues were available in the visual patterns. Results indicated that observers in the auditory condition displayed trial-by-trial selective attention to one or another frequency band as a function of the cues provided by earlier pattern components. In contrast, listeners in the visual condition displayed simultaneous attention to the two separate frequency bands that could possibly contain the tone, regardless of the information provided by the cues. Results are discussed in terms of single- and multiple-band models of attention.
Discrete representation of perceptual structure underlying consonant confusions
Authors: Soli Sigfrid D. , Arabie Phipps , Carroll J. Douglas
Published: October 2005

The perceptual representation of speech is generally assumed to be discrete rather than continuous, pointing to the need for general discrete analytic models to represent observed perceptual similarities among speech sounds. The INDCLUS (INdividual Differences CLUStering) model and algorithm [J. D. Carroll and P. Arabie, Psychometrika 48, 157–169 (1983)] can provide this generality, representing symmetric three-way similarity data (stimuli×stimuli×conditions) as an additive combination of overlapping, and generally not hierarchical, clusters whose weights (which are numerical values gauging the importance of the clusters) vary both as a function of the cluster and condition being considered. INDCLUS was used to obtain a discrete representation of underlying perceptual structure in the Miller and Nicely consonant confusion data [G. A. Miller and P. E. Nicely, J. Acoust. Soc. Am. 27, 338–352 (1955)]. A 14-cluster solution accounted for 82.9% of total variance across the 17 listening conditions. The cluster composition and the variations in cluster weights as a function of stimulus degradation were interpreted in terms of the common and unique perceptual attributes of the consonants within each cluster. Low-pass filtering and noise masking selectively degraded unique attributes, especially the cues for place of articulation, while high-pass filtering degraded both unique and common attributes. The clustering results revealed that perceptual similarities among consonants are accurately modeled by additive combinations of their specific and discrete acoustic attributes whose weights are determined by the nature of the stimulus degradation.
Mistuning a harmonic of a vowel: Grouping and phase effects on vowel quality
Authors: Darwin C. J. , Gardner R. B.
Published: October 2005

The harmonic sieve has been proposed as a mechanism for excluding extraneous frequency components from the estimate of the pitch of a complex sound. The experiments reported here examine whether a harmonic sieve could also determine whether a particular harmonic contributes to the phonetic quality of a vowel. Mistuning a harmonic in the first formant region of vowels from an /I/–/e/ continuum gave shifts in the phoneme boundary that could be explained by (i) phase effects for small amounts of mistuning and (ii) a harmonic sievelike grouping mechanism for larger amounts of mistuning. Similar grouping criteria to those suggested for pitch may operate for the determination of first formant frequency in voiced speech.
Coding of spectral fine structure in the auditory nerve. I. Fourier analysis of period and interspike interval histograms
Authors: Horst J. Wiebe , Javel Eric , Farley Glenn R.
Published: October 2005

The temporal fine structure of discharge patterns of single auditory- nerve fibers in adult cats was analyzed in response to signals consisting of a variable number of equal-intensity, in-phase harmonics of a common low-frequency fundamental. Two analytic methods were employed. The first method considered Fourier spectra of period histograms based on the period of the fundamental, and the second method considered Fourier spectra of interspike interval histograms (ISIH’s). Both analyses provide information about fiber tuning properties, but Fourier spectra of ISIH’s also allow estimates to be made of the degree of resolution of individual stimulus components. At low intensities (within 20–40 dB of threshold), indices of synchronization to individual components of complex tones were similar to those obtained for pure tones. This was true even when fibers were capable of responding to several signal components simultaneously. Response spectra obtained at low intensities resembled fibers’ tuning curves, and fibers with low spontaneous discharge rates tended to provide better resolution of stimulus components than fibers with high spontaneous rates. Strongly nonlinear behavior existed at higher stimulus intensities. In this, information was transmitted about progressively fewer signal components and about frequencies not present in the acoustic stimulus, and the component eliciting the largest response shifted away from the fiber’s characteristic frequency and toward the edges of the stimulus spectrum. This high-intensity ‘‘edge enhancement’’ can result from the combined effects of a compressive input–output nonlinearity, suppression, and the fortuitous addition of internally generated combination tones. The data indicate that sufficient information exists for the auditory system to determine the frequencies of narrowly spaced stimulus components from the temporal fine structure of nerve fiber’s responses.
Rate responses of auditory nerve fibers to tones in noise near masked threshold
Authors: Young Eric D. , Barta Patrick E.
Published: October 2005

The rate responses of auditory nerve fibers were measured for best frequency (BF) tone bursts in the presence of continuous background noise. Rate functions for BF tones were constructed over a 32-dB range of levels, centered on the behavioral masked thresholds of cats. The tone level at which noticeable rate changes are evoked by the tones corresponds closely to behavioral masked threshold at all noise levels used (−10- to 30-dB spectrum level). As the noise level increases, the response rate to the background noise approaches saturation, and the incremental rate response to tones decreases. At high noise levels, the rate responses to tones of low and medium spontaneous rate fibers are larger than those of high spontaneous rate fibers. Empirical statistics of auditory nerve fiber spike counts are reported; these differ from those expected of a Poisson process in that the variance is smaller than the mean. A new measure of discharge rate is described that allows rate changes to be expressed in units of a standard deviation. This measure allows tone-evoked responses to be interpreted in terms of their detectability in a signal detection task. Rate responses of low and medium spontaneous rate fibers are more detectable than those of high spontaneous rate fibers, especially at high noise levels. There appears to be sufficient information in the rate response of a small number of auditory nerve fibers to support behaviorally observed levels of detection performance.
Detection of tones in noise and the ‘‘severe departure’’ from Weber’s law
Authors: Carlyon Robert P. , Moore Brian C. J.
Published: October 2005

Thresholds were measured for the detection of 20-ms sinusoids, with frequencies 500, 4000, or 6500 Hz, presented in bursts of bandpass noise of the same duration and centered around the signal frequency. A range of noise levels from 35 to 80 dB SPL was used. Noise at different center frequencies was equated in terms of the total noise power in an assumed auditory filter centered on the signal frequency. Thresholds were expressed as the signal levels, relative to these noise levels, necessary for subjects to achieve 71% correct. For 500-Hz signals, thresholds were about 5 dB regardless of noise level. For 6500-Hz signals, thresholds reached a maximum of 14 dB at intermediate noise levels of 55–65 dB SPL. For 4000-Hz signals, a maximum threshold of 10 dB was observed for noise levels of 45–55 dB SPL. When the bandpass noises were presented continuously, however, thresholds for 6500-Hz, 20-ms signals remained low (about 1 dB) and constant across level. These results are similar to those obtained for the intensity discrimination of brief tones in bandstop noise [R. P. Carlyon and B. C. J. Moore, J. Acoust. Soc. Am. 76, 1369–1376 (1984); and R. P. Carlyon and B. C. J. Moore, accepted for publication in J. Acoust. Soc. Am.].