bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral differences in the ability of temporal gaps to reset the mechanisms underlying overshoot
Authors: McFadden Dennis
Published: October 2005

When very brief tonal signals are presented immediately after the onset of a gated noise masker, detectability can be 10–20 dB worse than when the signal is delayed by several hundred milliseconds, an effect known as the overshoot. It has long been known that, when an ‘‘onset’’ is created in an otherwise continuous, broadband masker by briefly turning it off and on again, the detectability of a brief signal presented soon after this temporal gap will decline gradually as the gap is increased from a few milliseconds to a few hundred milliseconds. In other words, the auditory system recovers to its quiescent, resting state following an adequate silent interval. Here, the broadband maskers consisted of three adjacent spectral bands—one centered on the frequency of the tonal signal, one low passed below the lower edge of the center band, and one high passed above the upper edge of the center band. The signal was a 2500-Hz tone having a total duration of 6 ms. In different blocks of trials, either all three bands, only the center band, or only the two flanking bands were temporally gapped by a duration ranging from 10–300 ms.

When the center band was about 750 Hz wide (about 2.5 critical bandwidths), this differential gapping process resulted in typical recovery functions when all three bands (the entire spectrum) or when just the two flanking bands were gapped. However, when only the center band was gapped, there was no evident recovery—rather, detectability remained near the signal level required with a continuous masker, even for a gap duration of 300 ms. That is, the process of recovery required that spectral regions adjacent to the 750 Hz centered on the signal frequency be temporally gapped; gapping the frequency components actually doing the masking was neither sufficient nor necessary. Once the center band was made 3000 Hz wide, and the flanking bands were made correspondingly narrower, gapping the center band did yield a typical recovery function—presumably because the relevant, adjacent spectral regions were now being affected by the gapping process—and gapping the relatively narrow, and remote, flanking bands did not produce a recovery function. These outcomes reveal that the standard neurophysiological explanation of the overshoot effect needs to be extended to include the contributions of adjacent frequency regions.
The influence of final-syllable position on the vowel and word duration of deaf talkers
Authors: Tye-Murray Nancy , Woodworth George
Published: October 2005

Hearing talkers produce shorter vowel and word durations in multisyllabic contexts than in monosyllabic contexts. This investigation determined whether a similar effect occurs for deaf talkers, a population often characterized as lacking coarticulation in their speech. Four prelingually deafened adults and two hearing controls produced three sets of word sequences. Each set included a kernel word and six derived forms (e.g., ‘‘speed,’’ ‘‘speedy,’’ ‘‘speeding,’’ etc.). The derived forms were created by adding unstressed and stressed syllables to the kernel form. A spectrographic analysis indicated that the deaf subjects did not always decrease word and vowel durations for the derivatives. Unlike hearing speakers, they often did not reduce vowel segments more than consonant segments. Three explanations are forwarded for the shortening effects. One relates to the implementation of temporal rules, the second concerns the organization imposed upon the articulators to produce speech, and the third suggests a language-independent vocal tract characteristic. The role of auditory information in developing the shortening effects is also considered.
A closed-form solution for removing the dead time effects from the poststimulus time histograms
Authors: Bi Qi
Published: October 2005

Discharge patterns from cochlear nerve fibers contain important information about acoustic stimuli and encoding schemes of the peripheral auditory system. Yet these patterns are distorted due to refractory or dead time effects. By modeling discharges from peripheral auditory nerves as a self-exciting Poisson process, the effects of dead time on a poststimulus time histogram can be determined, assuming the recovery time does not depend on acoustic stimuli. If the recovery function is known, a closed-form formula is available to remove the dead time distortions from the poststimulus time histogram.
Detecting single-cycle frequency modulation imposed on sinusoidal, harmonic, and inharmonic carriers
Authors: Carlyon Robert P. , Stubbs Richard J.
Published: October 2005

Thresholds for detecting frequency modulation (FM) of various carriers were measured in quiet and in noise. The carriers were either pure tones, harmonic complexes, or inharmonic complexes. The modulator was always a single cycle of a 12.5-Hz sinusoid. When the carrier was a complex tone, each component of that carrier was modulated by the same percentage of its starting frequency. This is the form of FM that occurs when the fundamental frequency (F0) of a complex sound is modulated. Threshold was defined in terms of this percentage frequency change. Two phases of the modulator were used, producing percepts of either upward or downward frequency glides. Experiment 1 used sinusoidal carriers with frequencies between 200 and 2400 Hz. Thresholds were constant for carrier frequencies of 1200 Hz and above, increased below 800 Hz, and were higher for the ‘‘down’’ than for the ‘‘up’’ glides, especially with low carrier frequencies. Experiment 2 measured thresholds for carriers consisting of three adjacent harmonics of complexes with F0’s of 50, 100, and 200 Hz as a function of the frequency of the center component of each complex (CF). Thresholds varied with CF in a similar way to those for the pure-tone carriers. In the frequency region 1200–2400 Hz, where thresholds did not vary with CF, they did not vary systematically with F0. Experiment 3 compared thresholds for a 20-component harmonic complex with those for an inharmonic complex. Thresholds were only slightly lower for the harmonic complex than for the inharmonic complex when presented in quiet, but were much lower when the complexes were presented in bursts of pink noise. Thresholds in noise for the completely harmonic complex were also lower than those for 20-component complexes in which only five adjacent components shared a harmonic relationship. It was concluded that a harmonic relationship between components occupying widely different frequency regions aids the detection of frequency modulation, particularly in the presence of noise.
Speech perception studies using a multichannel electrotactile speech processor, residual hearing, and lipreading
Authors: Cowan R. S. C. , Alcantara J. I. , Whitford L. A. , Blamey P. J. , Clark G. M.
Published: October 2005

Three studies are reported on the speech perception of normally hearing and hearing-impaired adults using combinations of visual, auditory, and tactile input. In study 1, mean scores for four normally hearing subjects showed that addition of tactile information, provided through the multichannel electrotactile speech processor, to either audition alone (300-Hz low-pass-filtered speech) or lipreading plus audition resulted in significant improvements in phoneme and word discrimination scores. Information transmission analyses demonstrated the effectiveness of the tactile aid in providing cues to duration, F1 and F2 features for vowels, and manner of articulation features for consonants, especially features requiring detection and discrimination of high-frequency information. In study 2, six different cutoff frequencies were used for a low-pass-filtered auditory signal. Mean scores for vowel and consonant identification were significantly higher with the addition of tactile input to audition alone at each cutoff frequency up to 1500 Hz. The mean speechtracking rate was also significantly increased by the additional tactile input up to 1500 Hz. Study 3 examined speech discrimination of three hearing-impaired adults. Additional information available through the tactile aid was shown to improve speech discrimination scores; however, the degree of increase was inversely related to the level of residual hearing. Results indicate that the electrotactile aid may be useful for patients with little residual hearing and for the severely to profoundly hearing impaired, who could benefit from the high-frequency information presented through the tactile modality, but unavailable through hearing aids.
Transient ultrasonic waves in a viscoelastic plate: Theory
Authors: Weaver Richard L. , Sachse Wolfgang , Niu Lin
Published: October 2005

The nearfield response of a thick viscoelastic plate at epicenter, off-epicenter, and on the same side of the plate to a point step load acting normal to the surface is discussed. The integral expressions resulting from Fourier and Hankel transforms of the governing equations are evaluated by two procedures. An asymptotic evaluation of the frequency-domain response is presented for high frequencies corresponding to ray arrivals. A numerical double inverse transform procedure is developed for obtaining exact time-domain waveforms.
Dynamic response of cross-ply laminated shallow shells according to a refined shear deformation theory
Authors: Reddy J. N. , Khdeir A. A.
Published: October 2005

The dynamic response of cross-ply laminated shallow shells is investigated using the third-order shear deformation shell theory of Reddy [J. Appl. Mech. 41, 47 (1984)]. The theory accounts for cubic variation of the in-plane displacements through the thickness and does not require shear correction coefficients. The state-space approach is used to develop the analytical solutions of simply supported, cross-ply shells using the classical, first-order, and higher-order theories. The use of the separation of variables technique for the higher-order theory is also presented. Numerical results of the higher-order theory for center deflection and normal stresses of spherical shells under various loadings are compared with those obtained using the classical and first-order [or Sanders, Q. Appl. Math. 21, 21–36 (1963)] shell theories.
Comments on ‘‘Two-mass models of the vocal cords for natural sounding voice synthesis’’ [J. Acoust. Soc. Am. 8
2, 1179–1192 (1987)]
Authors: Nudelman Harvey B. , Hoyt Bradley D.
Published: October 2005

Koizumi et al. [J. Acoust. Soc. Am. 82, 1179–1192 (1987)] have proposed a way to incorporate mucosal waves into previous two-mass mechanical models of the vocal folds. This was accomplished by allowing the mass of the masses to vary with time. The equations of motion Koizumi et al. used to mathematically describe this model neglected terms from the time rate of change of momentum of Newton’s second law. In this letter, approximations of the magnitude of this term indicate that it must not be neglected.
Resolution of steady-state sounds in simulated auditory space
Authors: Divenyi Pierre L. , Oliver Susan K.
Published: October 2005

A simulated acoustic equivalent of a sound source placed on the perimeter of a circle having a 4-m radius in the frontal horizontal half-plane was generated by obtaining, in 5-deg azimuthal steps, head-related transfer functions measured in both ears of an artificial head placed in an anechoic room. When an arbitrary sound is passed through the digital filter defined by the left and right transfer functions corresponding to a given angle, the sound will acquire a subjective azimuth comparable to the one at which the transfer function was measured [J. Blauert and P. Laws, Acustica 29, 273–277 (1973)]. This technique was used to measure the resolution of pairs of simultaneous steady-state stimuli (frequency-modulated, amplitude-modulated, and pure sinusoids or noises). The listener was required to identify the relative location of the two sounds. In one set of experiments, the position of the two sounds was fixed, and thresholds were obtained for the modulation- or carrier-frequency difference at which the two sounds could be localized. In other sets of experiments, the pair of sounds was constant and the minimum audible angular separation was determined at which association of each sound with a particular locus was possible. Generally, both kinds of resolution were better around the midline than at the sides. Angular resolution at the sides approached the threshold for the minimum audible angle between serially presented sounds only for pairs of complex (FM-) stimuli having little spectral overlap; for most other sound pairs, spatial resolution was possible only at angular separations of 60° and larger. Results suggest that segregation of the two component sounds and their correct localization constitute competing processes. Spatial resolution will be inefficient when either the localizability of the sounds is poor (e.g., for long-duration sine waves) or when the spectra of the two components display large regions of overlap (e.g., for two noise signals). The relationship between the data and the ‘‘cocktail-party effect’’ is discussed.
Vibrotactile masking: Effects of stimulus onset asynchrony and stimulus frequency
Authors: Gescheider G. A. , Bolanowski S. J. , Verrillo R. T.
Published: October 2005

Vibrotactile thresholds for the detection of a 50-ms vibratory stimulus on the thenar eminence of the hand were measured in the presence of and in the absence of a 700-ms suprathreshold vibratory masking stimulus. When thresholds were measured in the presence of the masking stimulus, stimulus onset asynchrony (SOA) was varied so that backward, simultaneous, and forward masking could be measured. The amount of masking, expressed as threshold shift, was greatest when the test stimulus was presented near the onset or offset of the masking stimulus. For both backward and forward masking, the amount of masking decreased as a function of increasing stimulus onset asynchrony. Comparisons were made of the amounts of masking measured when the test and masking stimuli were both sinusoids, and when the test stimulus was a sinusoid and the masking stimulus was noise. In all conditions, the masked threshold decreased approximately 4.0 dB when SOA was increased from 100 to 650 ms with reference to the onset of the 700-ms masking stimulus. More simultaneous masking was observed when sinusoidal test stimuli were detected in the presence of noise than when they were detected in the presence of sinusoidal maskers of the same frequency. The functions were essentially identical for detection of a low-frequency (20 Hz) test stimulus mediated by a non-Pacinian channel and detection of a high-frequency (250 Hz) test stimulus mediated by the Pacinian channel.
A model of spatiotemporal tactile sensitivity linking psychophysics to tissue mechanics
Authors: Van Doren Clayton L.
Published: October 2005

Sensitivities were measured for tangible spatiotemporal sinusoids applied to the index fingertip. The sinusoids had temporal frequencies of 8 and 128 Hz, in order to selectively activate the non-Pacinian I (NP I) and Pacinian (P) cutaneous mechanoreceptor systems, respectively, and had spatial frequencies from 0.00–1.03 cycles/mm. The sensitivity of the NP I system increased as the spatial frequency increased, whereas the sensitivity of the P system generally decreased as the spatial frequency increased. A mechanical model of the fingertip was used to calculate the normal and shear strains in the tissue, and a psychophysical linking hypothesis was introduced to predict tactile sensitivities based on the calculated strains. Specifically, the fingertip was modeled as a slab of a linear, isotropic, homogeneous, viscoelastic material. The boundary conditions were imposed by the spatiotemporal sinusoid at the top of the slab and the rigidly attached bone at the bottom of the slab. It was then assumed that the detection threshold was equal to the stimulus amplitude, which produced a constant, criterion strain at the location of the receptor. For both the P and NP I responses, the agreement between the predicted and measured sensitivities was best for calculations based on the normal strain, and for spatial frequencies below 0.5 cycles/mm. At higher spatial frequencies, the measured sensitivities were higher than predicted. The model also predicted the location of the P and NP I receptors in the tissue, the thickness of the tissue, and the value of the threshold strain for both receptor types. The predicted values agreed reasonably well with independent anatomical and physiological measurements.
Auditory-perceptual interpretation of the vowel
Authors: Miller James D.
Published: October 2005

The major issues in relating acoustic waveforms of spoken vowels to perceived vowel categories are presented and discussed in terms of the author’s auditory-perceptual theory of phonetic recognition. A brief historical review of formant-ratio theory is presented, as well as an analysis of frequency scales that have been proposed for description of the vowel. It is illustrated that the monophthongal vowel sounds of American English can be represented as clustered in perceptual target zones within a three-dimensional auditory-perceptual space (APS), and it is shown that preliminary versions of these target zones segregate a corpus of vowels of American English with 93% accuracy. Furthermore, it is shown that the nonretroflex vowels of American English fall within a narrow slab within the APS, with spread vowels near the front of this slab and rounded vowels near the back. Retroflex vowels fall in a distinct region behind the vowel slab. Descriptions of the vowels within the APS are shown to be correlated with their descriptions in terms of dimensions of articulation and timbre. Additionally, issues related to talker normalization, coarticulation effects, segmentation, pitch, transposition, and diphthongization are discussed.
Hot-film anemometry for measuring lateral line stimuli
Authors: Coombs Sheryl , Fay Richard R. , Janssen John
Published: October 2005

A hot-film anemometer system has been calibrated and evaluated for the measurement of sinusoidal water motions used in stimulating the mechanosensory lateral line system of a teleost fish. The response of the anemometer system to water motions created by a vibrating sphere was measured over a wide range of frequencies, intensities, and distances from the sphere. The amplitude response of the system to signals along the axis of sphere vibration was found to be linear over a 50-dB range for frequencies from 10–200 Hz, with the lowest end of the dynamic range (between 10−8 and 10−9 m) corresponding to physiological measures of best sensitivity in the lateral line system of the mottled sculpin, Cottus bairdi. The measured attenuation of the signal with distance was also linear over this frequency range out to distances of six times the radius (=3 mm) of the sphere and followed the predicted falloff rate for a dipolar source. The linear response of the anemometer system over a wide dynamic range encompassing the detection range of the lateral line system, and the match between predicted and measured motions at varying distances from a dipolar source, indicates that hot-film anemometry is a useful technique for measuring low-level, low-frequency signals likely to stimulate the lateral line system and other hydrodynamic detectors.
Frequency dependence of tissue attenuation measured by acoustic microscopy
Authors: Daft C. M. W. , Briggs G. A. D. , O’Brien W. D.
Published: October 2005

Broadband scanning acoustic microscopy (SAM) has been used to investigate the mechanical properties of sections of tissue with a resolution of around 8 μm. The work reported here extends these results by reporting the frequency dependence of the attenuation coefficient from 100–500 MHz. A discussion of the theory of the measurements is presented. The scanning laser acoustic microscope (SLAM) is used to characterize similar tissue sections at 100 MHz. The data obtained with the two forms of acoustic microscopy are compared with results from the literature.
A note on the viscous attenuation of sound in suspensions
Authors: Hay Alex E. , Mercer Douglas G.
Published: October 2005

An expression for the viscous attenuation coefficient in a suspension of solid particles is derived using the viscosity-modified phase shifts for a solid sphere presented in a previous article [Hay and Mercer, J. Acoust. Soc. Am. 78, 1761–1771 (1985)]. This expression reduces in the appropriate limits to the well-known result for viscous attenuation by small rigid mobile particles.
Acoustic eigenfrequencies of cavities with an internal obstacle: A modified perturbation theory
Authors: Mehl James B. , Hill Robert Nyden
Published: October 2005

The eigenfrequencies of a hard-walled acoustic cavity resonator are found by solving the Helmholtz equation with Neumann boundary conditions. A cavity C with an internal hard obstacle B of vanishing size was considered. Because the perturbation is never small in the neighborhood of the obstacle even in the limit of a small obstacle, a modified perturbation theory is required. A formalism was developed and tested by calculating the eigenfrequencies of a cylinder with an internal sphere on the axis. The results are compared with theoretical and experimental values determined by other investigators. The difference between the perturbation calculations and the numerical results varies from less than 10−5 to about 0.02 of the unperturbed eigenfrequency, depending on the size of the perturbing sphere and the mode.
Ray methods for flat and sloping shallow-water waveguides
Authors: Westwood Evan K.
Published: October 2005

A ray method for finding the acoustic field due to a point source in the presence of a plane, penetrable interface is extended to two simple models for shallow-water ocean environments: the flat, isovelocity waveguide (the Pekeris model) and the sloping, isovelocity waveguide (the penetrable wedge). In both cases, the sound speed in the bottom is assumed larger than that in the water. The total field is expressed as a sum of ray fields, each of which takes the form of a plane wave integral. The integrals are solved using the method of steepest descent, where the plane wave reflection and transmission coefficients are allowed to influence the location of the saddle points. For a Pekeris waveguide in which three modes are trapped, agreement between the ray model and the SAFARI model is nearly perfect at all ranges, while the discrete normal mode solution is in error when a mode is near cutoff. The ray model is accurate even when the water depth is half of the acoustic wavelength. For the penetrable wedge problem, the plane wave integral for the ray field is developed, and the origin of the multiple lateral wave fields is examined. Excellent agreement between the ray model and a two-way coupled mode model is demonstrated. Examples of the eigenray structure in both the flat and sloping waveguides are given.
The growth of and recovery from TTS in human subjects exposed to impact noise
Authors: Laroche C. , Hétu R. , Poirier S.
Published: October 2005

It is now recognized that temporary thrshold shift (TTS) grows to an asymptotic level (ATS) after a prolonged exposure to steady-state and intermittent noise. Few studies have been conducted to verify this process of acquisition for impact noise. However, results obtained on animals have demonstrated that an asymptote is reached after 1–2 h of exposure. These results have been confirmed in the present study on four human subjects using a 470- ms (B duration) impact noise at a rate of 1 pps. The above pattern of acquisition has been retested on two subjects exposed to the same impact for periods of 15–150 min. An ATS of 15–20 dB was measured (Lp=102–104 dBA) after 30–60 min of exposure. Recovery curves were determined for each exposure duration. They appeared to follow a logarithmic function of post-exposure time. It took from 30–50 min for one subject and from 4–5 h for other to completely recover. The time for total recovery did not seem to vary as a function of exposure time. Implications are drawn for damage risk criteria and for the study of the effects of impact noise on hearing.
Duration of frication noise required for identification of English fricatives
Authors: Jongman Allard
Published: October 2005

Natural speech consonant–vowel (CV) syllables ([f, s, θ, š, v, z, F] followed by [i, u, a]) were computer edited to include 20–70 ms of their frication noise in 10-ms steps as measured from their onset, as well as the entire frication noise. These stimuli, and the entire syllables, were presented to 12 subjects for consonant identification. Results show that the listener does not require the entire fricative–vowel syllable in order to correctly perceive a fricative. The required frication duration depends on the particular fricative, ranging from approximately 30 ms for [σ, z] to 50 ms for [f, s, v], while [θ, F] are identified with reasonable accuracy in only the full frication and syllable conditions. Analysis in terms of the linguistic features of voicing, place, and manner of articulation revealed that fricative identification in terms of place of articulation is much more affected by a decrease in frication duration than identification in terms of voicing and manner of articulation.
A logarithmic approach to fundamental frequency error measurement in speech
Authors: Krubsack David A. , Niederjohn Russell J.
Published: October 2005

The octave is a logarithmic unit of measure that offers significant advantages when applied to frequency error measurement. The octave provides an inherent normalization of frequency errors, displays harmonic errors, weights reciprocal errors equally, and can easily be interpreted in either the time or frequency domain. In this letter, the octave is compared with three commonly used frequency error measures. To illustrate the advantages of the octave as an error measure, its application to fundamental frequency estimation error in speech is discussed.
Spectral power determinations of compressibility and density variations in model media and calf liver using ultrasound
Authors: Waag R. C. , Dalecki D. , Christopher P. E.
Published: October 2005

A model of scattering is used to relate average differential scattering cross section and power spectra of scattering medium variations. The model expresses the average differential scattering cross section as a sum of the power spectrum of medium compressibility variations, the power spectrum of density variations weighted by the square of the cosine of the scattering angle, and the cross-power spectrum of compressibility and density variations weighted by twice the cosine of the scattering angle. Known values of the average differential scattering cross section at a minimum of three different scattering angles and temporal frequencies corresponding to the same spatial frequency are used to calculate each of the three power spectra. Since noise and statistical fluctuations are present in actual measurements of average differential scattering cross section, the calculations of power spectra are obtained from an overdetermined set of equations to which a solution is found by using a singular value decomposition. Data derived from a model for scattering from a cloud of correlated particles are employed to show the influence of additive noise. Calculations are also made from measurements of scattering from three suspensions of particles that have a different average radius in each suspension but are similarly modeled by scattering from a cloud. Additionally, the calculations are applied to measurements of average differential scattering cross section of calf liver. The results show that determinations of the power spectra of scattering medium variations can be made under practical conditions, and also imply that density variations contribute significantly to scattering by calf liver.
Acoustical higher-order mode scattering matrix of circular nonuniform lossy tubes without flow
Authors: Hudde Herbert
Published: October 2005

In this paper, the acoustical behavior of circular ducts with nonuniform area functions is considered in terms of a corresponding scattering matrix. The elements of the scattering matrix denote the portions of reflected and transmitted waves of the mode order k when a wave of mode order n is incident. This way, the approach is able to treat wave modes of arbitrary order. When the tube under consideration consists of sections of constant cross-sectional area, the method of calculation can be applied directly. Otherwise, the (continuous) area function has to be approximated by a corresponding step function; i.e., the tube is modeled by a certain number of contiguous sections (stepped duct approximation). In contrast to other publications, the area function is not restricted to be slowly varying along the tube axis. Losses as well as liners are simply taken into account by altering propagation constants and wave impedances, correspondingly. After derivation of the numerical algorithm, some examples of nonuniform ducts are investigated. The results are compared to some low-frequency solutions. The accuracy of numerical results depends on some parameters occurring in the algorithm presented. The influence of different parameters on the resulting accuracy is investigated. Finally, the theory is verified by a measurement.
Detection and discrimination of frequency modulation of complex signals
Authors: Horst J. Wiebe
Published: October 2005

Detection and discrimination of frequency modulation were studied for harmonic signals with triangular spectral envelopes. The center frequency of the stimuli was near 2 kHz; the fundamental frequency was near 100 Hz. To prevent the possibility that the discrimination was based on differences of initial or final frequencies, these frequencies were equal within and across modulations in each individual experiment. Differences between modulations consisted of differences in the trajectories between the initial and final frequencies. Performance worsened as the slopes of the spectral envelopes decreased. Addition of noise also impaired modulation discrimination. The dependence on the signal-to-noise ratio was similar to what is found for stationary stimuli: Discrimination of frequency modulation deteriorated more rapidly with decreasing signal-to-noise ratio when stimuli had shallow spectral slopes than when they had steep spectral slopes. In spite of the precautions taken (i.e., initial and final frequency the same), the discrimination of these stimuli was more likely based on quasistationary frequency discrimination than on discrimination of modulation rate. This conclusion is consistent with previous findings for pure tones presented in quiet that frequency discrimination is more acute than modulation-rate discrimination.
Reply to ‘‘Comments on ‘earphones in audiometry’ ’’ [M. C. Killion and E. Villchur, J. Acoust. Soc. Am. 8
5, 1775–1778 (1989)]
Authors: Zwislocki Jozef J.
Published: October 2005

This is a reply to the Letter to the Editor of Killion and Villchur [J. Acoust. Soc. Am. 85, xxx–xxx (1989)] in which these authors take issue with a report of CHABA WG 91 [Zwislocki et al., J. Acoust. Soc. Am. 83, 1688–1689 (1988)] on ‘‘Earphones in audiometry.’’ The conclusion of WG 91, that the use of supraaural earphones should not be discontinued in favor of either circumaural or insert earphones, is further justified.
Neuromagnetic steady-state responses to auditory stimuli
Authors: Hari Riitta , Hämäläinen Matti , Joutsiniemi Sirkka-Liisa
Published: October 2005

Steady-state magnetic responses to clicks presented at rates between 10 and 70 Hz have been recorded in healthy humans. The responses were highest in amplitude around 40 Hz. This amplitude enhancement is satisfactorily explained by summation of responses evoked by single clicks. The field maps suggest activation of the auditory cortex at all stimulus frequencies. Similar responses were obtained with gated noise bursts and by pauses in a series of clicks. The mean ‘‘apparent latency,’’ determined from the phase lag at rates 30–70 Hz, was 54 ms. The physiological relevance of this quantity is shown to be questionable.
Observations of low-frequency acoustic interaction with the ocean surface
Authors: Mitchell Stephen K. , Machell Fredrich W.
Published: October 2005

Measurements were made using the power spectra of signals received at 1650-m depth from a 250- to 650-Hz broadband projector which was towed at 60-m depth; the range of ray-path grazing angles was from 23° to 73°. The spectra display significant modulation with frequency in accordance with the Lloyd’s mirror effect. At lower frequencies and lower grazing angles, the amplitude of the spectral modulations is greatest, in accordance with the notion that the surface-reflection loss will be smaller for lower frequencies and grazing angles. For 110 spectra, the amplitude of the spectral modulation was measured. Then, the modulation samples were converted to estimates of coherent surface-reflection loss, and averaged reflection coefficients were compared with model calculations. Our findings are similar to those of the work of Clay et al. [J. Acoust. Soc. Am. 53, 1677–1682 (1973)] with laboratory reflection measurements. That is, the data are reasonably represented by the predictions of Eckart if a non-Gaussian form for the probability density function of the surface heights is used. The probability function that was used is consistent with the notions that the sea surface has rounded troughs and sharp crests, and that shadowing may occur.
Analysis of acoustic wave scattering by scatterers in layered media using the hybrid ray–mode (boundary integral equation) method
Authors: Lu I-Tai
Published: October 2005

Acoustic wave scattering by scatterers in layered media is studied using a new method that combines the hybrid ray–mode and boundary integral equation methods. The latter is used to formulate the scattering process and the former is used to provide the Green’s function of the layered environment. Following standard procedures of the boundary integral equation method, integral equations are formulated first for field distributions along the boundaries of the obstacles. By expressing these unknown distributions in terms of appropriate basis functions, the integral equations are then reduced to algebraic equations that are solved numerically. In the integral equations, it is necessary to compute the Green’s function of the layered environment for various arrangements of locations of source and receiver. None of these conventional approaches (rays, modes, and spectral integration) to evaluate the Green’s function are satisfactory for all possible arrangements. Only the newly developed hybrid ray–mode method is best suited for this purpose because it combines rays and modes self-consistently within a single framework and optimizes the advantages of each. Numerical implementation illustrates these aspects.
Location of pointlike acoustic emission sources in anisotropic plates
Authors: Castagnede Bernard , Sachse Wolfgang , Kim Kwang Yul
Published: October 2005

In this paper is described a method by which a pointlike source of acoustic emission can be located in an anisotropic plate. The method is applicable for a source in an anisotropic solid of arbitrary symmetry as long as the principal acoustic axes of the material are known a priori. It is shown that from the time-of-flight differences of particular features in the waveforms detected by any pair of sensors, a set of nonlinear transcendental equations can be formed in which the coefficient of each term in the equations is related to the time-of-flight differences, the geometrical parameters of the array, and the wave speeds of quasiwaves propagating along each source/receiver path. For waves propagating in principal planes, the analytical expressions for the wave speed values are used. Extension to nonprincipal planes is obtained by computing the eigenvalues of the Green–Christoffel tensor. Determination of the optimum location of the source is found by minimizing the Euclidean functional associated with the set of transcendental nonlinear equations. The results obtained with numerical simulations of two- and three-dimensional source-location problems are presented to illustrate several characteristic features of the solution. Also shown are the results of two-dimensional source-location measurements made on specimens of a unidirectional fiber-glass-reinforced composite material. The results demonstrate the efficiency of the algorithm in locating a source of emission.
Transient elastic wave scattering by a rigid spherical inclusion
Authors: Wijeyewickrema Anil C. , Keer Leon M.
Published: October 2005

The transient scattering of a stress wave by a rigid spherical inclusion embedded in an infinite elastic medium is considered. The Fourier synthesis technique is used to calculate the response of the inclusion and the interfacial stresses. This method of solution yields an exact solution for the inclusion response. The interfacial stresses are obtained in the form of an infinite series that is suitable for the long-time response but that does not converge rapidly for early time. Hence, an early time analysis is performed by reformulating the problem in the Laplace transform domain; by utilizing Watson’s transformation, the early time stress response in the shadow region is obtained. Results in the shadow region using both techniques emphasize the importance of carrying out the early time analysis. The interfacial stresses in the illuminated zone using only the Fourier synthesis method are also given.
Determination of the shear impedance of viscoelastic liquids using Love and Bleustein–Gulyaev surface waves
Authors: Kiel/czyński P. , Pl/owiec R.
Published: October 2005

This paper presents a new method, using shear SH (shear horizontal) surface waves in solids, to determine the rheological parameters of viscoelastic liquids. Appropriate analytical formulas have been derived for Love and Bleustein–Gulyaev surface waves. The sensitivity of the proposed method is compared to that of the classical Mason method employing SH bulk waves. The measuring range of the proposed and classical methods is discussed in detail. Preliminary measurements are performed for typical mineral oil. The measured quantities agree very well with those obtained theoretically. The proposed method can be a few orders of magnitude more sensitive than the bulk wave method.
On a theoretical interpretation of the prevalence rate of noise-induced annoyance in residential populations—High-amplitude impulse-noise environments
Authors: Schomer Paul D.
Published: October 2005

In a recent paper, Fidell et al. [J. Acoust. Soc. Am. 84, 2109–2113 (1988)] have introduced a theoretical interpretation of the prevalence rate of noise-induced annoyance in residential populations exposed to common environments consisting of sources such as aircraft, motor vehicles, etc. Their model assumes a compressive transformation of DNL, and they assert that ‘‘the quantity that engenders annoyance must be strongly related to the apparent magnitude of noise exposure.’’ Thus they use the well-known finding that apparent loudness is proportional to the 0.3 root of acoustic energy. High-amplitude impulse noise has been shown to be different from typical community noise, in part because it induces vibrations and rattles in structures. So the annoyance response is due both to the audible sound and to the induced vibrations and rattles; the latter should be proportional to the 0.5 power of DNL. In this letter, a compressive transformation coefficient of 0.4 (midway between 0.3 and 0.5) is used for high-amplitude impulse sound. The results show excellent fit between theory and results. On the one hand, this fit supports the view of the Committee on Hearing Bioacoustics and Biomechanics (CHABA), a view that induced vibrations and rattles (and not only loudness) determine annoyance to high-amplitude impulse noise, and, on the other hand, this close fit lends further credence to the Fidell model.
Effect of the pulse length of ultrasound on cell membrane damage i
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Authors: Kober Lorenz O. , Ellwart Joachim W. , Brettel Hans
Published: October 2005

Suspended cells of a human lymphoblastic cell line were exposed to pulsed ultrasound of 775 kHz. The pulse lengths were varied between 16 and 1000 μs. The mark/space ratio was always kept at 1:1. Two ultrasound intensity levels were used: 3.6 and 6.4 W/cm2 spatial peak and temporal peak. After an exposure time of 5 min, cell membrane damage was measured cytometrically by a dye exclusion test. No membrane damage was observable at 16 μs, whereas, at pulse lengths of 1000 μs, about one-third of the cells were damaged.
Theory of acoustical edge waves
Authors: Ufimtsev Pyotr Ya.
Published: October 2005

The physical theory of diffraction is applied to acoustical diffraction problems, using the concept of elementary edge waves scattered in the vicinity of an infinitesimal edge element. Far from the edge element, these elementary edge waves are described by the circular function of complex arguments. Various definitions of elementary edge waves are discussed. The theory is formulated in general form, namely for the scattering surfaces with arbitrary sharp edges. Faces of edges are assumed to be acoustically soft or hard and the edges themselves are assumed to be smoothly curved (in terms of wavelength). An angle between faces varies slowly along the edge. This theory enables one to calculate the dominant term in the high-frequency asymptotic expansion for primary and multiple edge waves. Asymptotics of this kind are found for the scattered field in the ray region, near a smooth caustic, on the shadow boundary, and along a focal line. The connection between the physical theory of diffraction and other asymptotic methods is established.
Perceptual cues for place of articulation for the voiced pharyngeal and uvular consonants
Authors: Alwan Abeer
Published: October 2005

A series of perceptual experiments was conducted to investigate the perceptual cues for place of articulation for the voiced pharyngeal /// and the voiced uvular /3/ consonants in Arabic. Synthetic consonant–vowel stimuli, in which the vowel was the long vowel /aa/ of Arabic, were used in the experiments. In the first experiment, stimulus continua were constructed by systematically varying the trajectories of the first and second formant frequencies (F1 and F2) independently between the values appropriate for the two consonants. In the second experiment, the bandwidth of F2 for the pharyngeal stimuli and the bandwidth of F1 for the uvular stimuli were manipulated. Results of the first experiment show that the onset value of F1(F1o) is essential in discriminating between the two consonants, while that of F2 is not. Results of the second experiment show that widening the bandwidth of F1 increases the percent of uvular responses and enhances the naturalness of the uvular stimuli, whereas it decreases substantially the number of pharyngeal responses. Increasing the bandwidth of F2 had no effect on either the percent identification of the pharyngeal or the naturalness of the synthetic stimuli.
Transfer function method for measuring characteristic impedance and propagation constant of porous materials
Authors: Utsuno Hideo , Tanaka Toshimitsu , Fujikawa Takeshi , Seybert A. F.
Published: October 2005

A method for measuring the characteristic impedance and propagation constant of porous materials is described in this paper. Measurements were performed based on a surface impedance method that required a set of distinct acoustic impedances derived at the material surface. This requirement is satisfied by arbitrarily changing the air space depth behind the material, and then a new formulation is derived so that a recently developed method of determination, called the transfer function method, can be applied. An appropriate set of air space depths is also discussed. Glass wool and porous aluminum were used to assess the usefulness of the present method. The normal acoustic impedance and normal absorption coefficient of the test materials with arbitrary thicknesses or with an arbitrary air space depth behind them were calculated from the obtained characteristic impedance and propagation constant and were compared with the measured values that were obtained directly by using the transfer function method. The good agreement achieved suggests that the present method is reliable and effective enough to measure the characteristic impedance and propagation constant over a broadband frequency range.
Balanced noise-criterion (NCB) curves
Authors: Beranek Leo L.
Published: October 2005

The widely used noise-criterion (NC) curves are not based on the American National Standard (four-band) definition for speech-interference level (SIL) and do not extend down to the 31.5- and 16-Hz octave bands. In addition, experience has shown that the procedure originally recommended for using the curves to determine whether a measured noise in a space is acceptable to occupants should be replaced. The premises underlying the new balanced noise-criterion (NCB) curves are: (1) Use the American National Standard SIL as the rating number for each curve; (2) achieve spectral balance by making equal the calculated octave-band loudnesses for those bands with midfrequencies between 16 and 8000 Hz that contain the same number of critical bands—otherwise, weight downward the loudnesses in proportion to the number of critical bands contained; and (3) satisfy earlier studies that the difference between the overall calculated loudness level and the SIL for each curve must not exceed approximately 24 units. The NCB curves are used (1) before construction, to specify acceptable octave-band noise levels, and (2) after construction, to rate the noise as to its effect on speech communication; as to any spectral imbalance (e.g., rumble or hiss), including how many decibels of noise reduction are needed in each octave band to eliminate spectral imbalance; and as to excess low-band levels that might cause feelable or audible structural vibrations. The NCB curves have successfully predicted all cases of sizable complaints by occupants of existing building spaces accessed for this study.
Boundary integral-Gaussian beam method for seismic wave scattering: S
H waves in two-dimensional media
Authors: Benites Rafael , Aki Keiiti
Published: October 2005

A new method is introduced based on Gaussian beam superposition to calculate the scattering of plane SH waves by strong lateral heterogeneities buried in a two-dimensional (2-D) homogeneous half-space. In dealing with strong lateral heterogeneities, explicit formulas are not used for transmitted and reflected beams at discontinuous boundaries, which implies that no local modification of the asymptotic solution at the interface is necessary. Instead, artificial sources of beams are located at selected points along the boundaries to represent the transmitted and reflected fields. The boundary conditions are satisfied in the least-squares sense. To test the method, three well-known problems of scattering plane SH waves have been solved. In the first, the surface motion of a semicylindrical canyon has been calculated; in the second, the surface motion of a cosine-shaped mountain has been calculated; and, in the third, the ground response of a semicylindrical alluvial valley over a half-space has been calculated. Results are in excellent agreement with the corresponding exact or other numerical solutions. Finally, the method was used to calculate the effects of cylindrical inclusions on the surface ground motion. An interesting effect of a low-velocity inclusion that traps energy by resonance and reduces amplitude at the surface above the inclusion was found.