bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic heating of lung tissue
Authors: Hartman C. L. , Child S. Z. , Penney David P. , Carstensen E. L.
Published: October 2005

Tests with mice show that lung tissue is not selectively heated in comparison with other soft tissues and that lung has an efficient mechanism for dissipating that heat which is produced. Temperatures measured with a fine thermocouple placed at the outer surface of the mouse lung show approximately 1 °C total rise in temperature in the living animal for an incident intensity of 1 W/cm2 (4 MHz, unfocused sound field).
Improving performance for matched field processing with a minimum variance beamformer
Authors: Ozard John M. , Brooke Gary H. , Brouwer Peter
Published: October 2005

Matched field processing (MFP) employing reduced minimum variance beamforming (RMVB) has been described in the literature as being robust to signal phase errors for vertical line arrays in modal noise. These techniques are extended to horizontal line arrays and evaluated for both horizontal and vertical arrays. The evaluation of RMVB is also more general in that it is extended to white and modal noise fields in the presence of phase or amplitude errors. Two phase error models were employed, one corresponding to constant sensor-position errors the other to short-term fluctuations of mode phase during the covariance matrix estimation. For minimum variance beamforming (MVB), in the presence of both types of random phase errors, array gain, peak-to-sidelobe ratios, and peak-to-background ratios all decreased in a modal noise field. Performance was far less sensitive to phase errors in spatially white noise than in modal noise. MVB was modified by reducing the number of eigenvectors employed in the matching. For the modified forms performance was improved over that of MVB with an attendant reduction in the number of computations. The equispaced horizontal arrays consistently outperformed and were more robust than the equispaced vertical arrays. Similar results were obtained with amplitude errors that were constant during the estimation.
High-frequency ultrasonic wave propagation in polycrystalline materials
Authors: Rokhlin S. I. , Bolland T. K. , Adler L.
Published: October 2005

Ultrasonic propagation through a multigrained anisotropic medium is studied in the high-frequency (geometric) region via supercomputer simulation. The grains and their boundaries are considered randomly oriented. Material texture is also included in the model. A ray-tracing approach is used with an exact solution for reflection and transmission of ultrasonic waves at grain boundaries. Transmission losses are studied for both phase-sensitive and phase-insensitive receiving transducers. Dependence of transmission loss and wave phase distribution on grain size and anisotropy is considered. It is shown that at high anisotropies the transmission loss for a fixed distance between transmitter and phase-sensitive receiver passes through a minimum as a function of the grain size. The wave-front orientation angles and the beam deviations at the receiving transducer are also found.
Phonoscopy: An acoustical holography technique for plane structures radiating in enclosed spaces
Authors: Villot M. , Chavériat G. , Roland J.
Published: October 2005

The present paper provides a modification of near-field acoustical holography (NAH) enabling reconstruction of sound fields in a room in order to study plane structures radiating in enclosed spaces; the new technique is called phonoscopy. A description of the measurement laboratory is given; a single microphone scanner is used to measure the pressure on the hologram plane. Three examples of measurement are presented: a point source located on a rigid wall, a homogeneous wall, and a window mounted in a wall. Maps of the velocity of the structure and of the acoustic intensity radiated are given. The accuracy of phonoscopy is demonstrated by comparison with the accelerometer methods (for measuring vibration velocities) and the two-microphone technique (for measuring acoustic intensities). Some K-space spectra are also presented and analyzed, giving more information about the physics of the vibrator.
Modeling the identification of concurrent vowels with different fundamental frequencies
Authors: Meddis Ray , Hewitt Michael J.
Published: October 2005

Human listeners are better able to identify two simultaneous vowels if the fundamental frequencies of the vowels are different. A computational model is presented which, for the first time, is able to simulate this phenomenon at least qualitatively. The first stage of the model is based upon a bank of bandpass filters and inner hair-cell simulators that simulate approximately the most relevant characteristics of the human auditory periphery. The output of each filter/hair-cell channel is then autocorrelated to extract pitch and timbre information. The pooled autocorrelation function (ACF) based on all channels is used to derive a pitch estimate for one of the component vowels from a signal composed of two vowels. Individual channel ACFs showing a pitch peak at this value are combined and used to identify the first vowel using a template matching procedure. The ACFs in the remaining channels are then combined and used to identify the second vowel. Model recognition performance shows a rapid improvement in correct vowel identification as the difference between the fundamental frequencies of two simultaneous vowels increases from zero to one semitone in a manner closely resembling human performance. As this difference increases up to four semitones, performance improves further only slowly, if at all.
Intensity and frequency resolution: Masking of absolute identification and fixed and roving discrimination
Authors: Mori Shuji , Ward Lawrence M.
Published: October 2005

Auditory intensity and frequency resolution were studied in three paradigms under masking conditions. Absolute identifications of single stimuli (one-interval paradigm) and 2IFC judgments of fixed- and roving-level pairs of stimuli (two-interval paradigm) were obtained from the same experienced observers. Judgments were made under optimal (no mask) conditions, in the presence of a broadband noise mask (simultaneous mask), and when the stimulus(i) to be judged were either preceded (forward mask) or followed (backward mask) by a broadband noise mask. Substantial masking of intensity resolution was found in all mask conditions. Only a simultaneous mask affected frequency resolution. In the no mask condition, performance was best for fixed-level (or frequency) 2IFC discrimination, followed by roving-level (frequency) 2IFC, and finally absolute identification. These differences were maintained under masking for frequency resolution, but not for intensity resolution. The results are discussed in terms of the Braida and Durlach (1988) model of intensity resolution. A similar model is suggested for frequency resolution with differences suggested by the differences in neural coding of sound intensity and frequency.
Equivalent networks for representing the two-dimensional propagation of dilatational and shear waves in infinite elastic plates and in stratified elastic media
Authors: Rudgers Anthony J.
Published: October 2005

An elastic plate (lamina) of infinite lateral extent, in which there exists a plane-wave elastic field owing to propagating dilatational and shear waves, is represented by a four-port equivalent network. The equations describing this equivalent network are mathematically identical to those equations taken from the theory of linear elasticity that describe the mechanical behavior of a plate with arbitrary plane-wave excitation of its surfaces. The equivalent network comprises two coupled transmission lines, one line representing dilatational-wave propagation and the other shear-wave propagation within the plate. A pair of ports at each plate surface transmit the normal and the transverse stresses acting at the surfaces to the input and output ports of the two transmission lines. The surface ports are coupled to the transmission-line ports by an arrangement that includes both multiwinding ideal transformers and gyrators. Gyrators are required in the network that is the topological equivalent of an elastic plate in order to make the network equations identical to the equations resulting from the theory of linear elasticity. Consequently, the network demonstrates that mode conversion at the boundaries of an elastic plate (i.e., the conversion of dilatational-wave motion into shear-wave motion and vice versa) is a nonreciprocal phenomenon. By cascade interconnection of appropriate equivalent networks of the kind reported, a network model can be constructed that fully and exactly describes two-dimensional elastic-wave propagation in an arbitrarily stratified medium.
Discrimination of interaural envelope correlation and its relation to binaural unmasking at high frequencies
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2005

Listeners’ sensitivity to interaural correlation of the envelope of high-frequency waveforms and whether such sensitivity might account for detectability in a masking-level difference paradigm were assessed. Thresholds of interaural envelope decorrelation (from a reference correlation of 1.0) were measured for bands of noise centered at 4 kHz and bandwidths ranging from 50–1600 Hz. Decorrelation of the envelope was achieved by ‘‘mixing’’ two independent narrow-band noises. Separately, with the same listeners, NoSo and NoSπ detection thresholds were measured for maskers of the same center frequency and bandwidths. For bandwidths of noise up to about 400 Hz, listeners were similarly sensitive to interaural decorrelation in both types of task. However, for bandwidths greater than 400 Hz or so, while sensitivity in the discrimination task was unaffected, sensitivity was reduced in the NoSπ conditions. Additional data suggested that listeners were able to maintain their sensitivity independent of bandwidth in the discrimination task by focusing on binaural information within select spectral regions of the stimuli.
Spectral integration of broadband signals in diotic and dichotic masking experiments
Authors: Langhans Angela , Kohlrausch Armin
Published: October 2005

The method of Gässler [Acustica 4, 408–414 (1954)] was used to measure the audibility of multicomponent signals as a function of their bandwidth against a broadband, white-noise masker. Test signals were composed of 1 to 41 sinusoids with a spectral spacing of 10 Hz and were always spectrally centered around 400 Hz. Masker duration was 400 ms and the 300-ms signals were centered within the noise intervals. A three-interval forced-choice procedure with adaptive level adjustment was applied. NoSo, NoSm, NoSπ, and NπSo masked thresholds were obtained for four subjects. A comparison of the diotic and the three dichotic conditions yields no significant difference in the bandwidth dependence and suggests equal integration bandwidths for all conditions. However, the original results of Gässler could not be replicated: Neither were the overall levels of signals with a bandwidth below the critical bandwidth constant nor were the results for broadband signals in accordance with a single-band model of detection. The narrow-band data are much better described by calculating the overall signal level at the output of a rounded exponential filter [Patterson et al., J. Acoust. Soc. Am. 72, 1788–1803 (1982)] with an equivalent rectangular bandwidth of 65 Hz. For broader signal bandwidths, the signal level at threshold increases as predicted by a multiband model.
Potential benefits of adaptive frequency-gain characteristics for speech reception in noise
Authors: Rankovic Christine M. , Freyman Richard L. , Zurek Patrick M.
Published: October 2005

Some current single-microphone hearing aids employ techniques for adaptively varying the frequency-gain characteristic in an attempt to improve speech reception in noise. The potential benefit of this strategy depends on the spectral spread of masking and the degree to which it can be reduced by changing the frequency-gain characteristic. In this study these benefits were examined for subjects with normal hearing under static listening conditions. In the unprocessed condition, subjects were presented with nonsense syllables in an octave-band noise centered on 0.5, 1, or 2 kHz. The frequency-gain characteristic was then modified with the goal of reducing the intensity of the frequency region containing the octave-band noise. This processing resulted in increases as large as 60 percentage points in consonant-correct scores with the low- and mid-frequency octave noise bands, and a small increase with the high-frequency noise. Masking patterns produced by the octave noises were also measured and were related to the intelligibility results via an analysis based on Articulation Theory. The Articulation Index was also used to compare the effectiveness of three adaptive rules. A simple multiband volume control is expected to provide much of the benefit of more sophisticated systems without the need for separate estimation of input speech and noise spectra.
On the sufficiency of compound target specification of isolated vowels and vowels in /bVb/ syllables
Authors: Andruski Jean E. , Nearey Terrance M.
Published: October 2005

It has been suggested [e.g., Strange et al., J. Acoust. Soc. Am. 74, 695–705 (1983); Verbrugge and Rakerd, Language Speech 29, 39–57 (1986)] that the temporal margins of vowels in consonantal contexts, consisting mainly of the rapid CV and VC transitions of CVC’s, contain dynamic cues to vowel identity that are not available in isolated vowels and that may be perceptually superior in some circumstances to cues which are inherent to the vowels proper. However, this study shows that vowel-inherent formant targets and cues to vowel-inherent spectral change (measured from nucleus to offglide sections of the vowel itself) persist in the margins of /bVb/ syllables, confirming a hypothesis of Nearey and Assmann [J. Acoust. Soc. Am. 80, 1297–1308 (1986)]. Experiments were conducted to test whether listeners might be using such vowel-inherent, rather than coarticulatory information to identify the vowels. In the first experiment, perceptual tests using ‘‘hybrid silent center’’ syllables (i.e., syllables which contain only brief initial and final portions of the original syllable, and in which speaker identity changes from the initial to the final portion) show that listeners’ error rates and confusion matrices for vowels in /bVb/ syllables are very similar to those for isolated vowels. These results suggest that listeners are using essentially the same type of information in essentially the same way to identify both kinds of stimuli.

Statistical pattern recognition models confirm the relative robustness of nucleus and vocalic offglide cues and can predict reasonably well listeners’ error patterns in all experimental conditions, though performance for /bVb/ syllables is somewhat worse than for isolated vowels. The second experiment involves the use of simplified synthetic stimuli, lacking consonantal transitions, which are shown to provide information that is nearly equivalent phonetically to that of the natural silent center /bVb/ syllables (from which the target measurements were extracted). Although no conclusions are drawn about other contexts, for speakers of Western Canadian English coarticulatory cues appear to play at best a minor role in the perception of vowels in /bVb/ context, while vowel-inherent factors dominate listeners’ perception.
A new portable sound processor for the University of Melbourne/Nucleus Limited multielectrode cochlear implant
Authors: McDermott Hugh J. , McKay Colette M. , Vandali Andrew E.
Published: October 2005

A new processor, called the spectral maxima sound processor (SMSP), has been developed for the University of Melbourne/Nucleus Limited multielectrode cochlear implant. The SMSP analyses sound signals by means of a bandpass filterbank having 16 channels which are allocated tonotopically to the implanted electrodes. Every 4 ms, typically, the six channels with the largest amplitudes are selected, and six corresponding electrodes are activated. In an ongoing study the performance of the SMSP is being compared with that of the Mini Speech Processor (MSP). Some results of speech perception tests from the first two SMSP users are presented, in which scores for the recognition of vowels, consonants, and words all showed significant increases over the corresponding MSP scores.
An adaptive method for tracking voicing irregularities
Authors: Qi Yingyong , Shipp Thomas
Published: October 2005

A method has been developed for tracking irregularities in the acoustic waveform of a sustained phonation using the adaptive Wiener filter. Irregularities are determined by the technique of correlation cancellation. The algorithm is evaluated using sustained vowels produced by a formant synthesizer and by subjects with and without phonatary disorders. Results indicate that the method is capable of differentiating between normal and abnormal voices. Most significantly, however, it can also track sporadic or nonstationary irregularities in the shape of an individual acoustic wavelet. This method is expected to be a useful tool for the acoustic analysis of voice production.
Formant frequency estimates for abruptly changing area functions: A comparison between calculations and measurements
Authors: Sundberg Johan , Lindblom Björn , Liljencrants Johan
Published: October 2005

Vocal tract area functions may contain quite abrupt changes in cross-sectional area. In formant frequency calculations for such area functions, an inner length correction (ILC) should be applied. The relevance of this correction was investigated by comparing acoustic measurements obtained from a physical model of the vocal tract with data gathered by means of computer simulations. Calculating formant frequencies without applying internal length corrections caused substantial errors, particularly for area functions representing apical stops just anterior to occlusion. Decentering and axial symmetry in the arrangement of the area elements of the physical model were briefly studied and found to have effects on the formant frequency values.
Formant frequencies in Estonian folk singing
Authors: Ross Jaan
Published: October 2005

Formant frequencies in an old Estonian folk song performed by two female voices were estimated for two back vowels /a/ and /u/, and for two front vowels /e/ and /i/. Comparison of these estimates with formant frequencies in spoken Estonian vowels indicates a trend of the vowels to be clustered into two sets of front and back ones in the F1/F2 plane. Similar clustering has previously been shown to occur in opera and choir singing, especially with increasing fundamental frequency. The clustering in the present song, however, may also be due to a tendency for a mid vowel to be realized as a higher-beginning diphthong, which is characteristic of the North-Estonian coastal dialect area where the singers come from. No evidence of a ‘‘singer’s formant’’ was found.
Radiation or scattering from multiple axisymmetric cylinders
Authors: Sarkissian Angie
Published: October 2005

The boundary-element method is applied to solve for the radiation or scattering from multiple cylinders having given surface normal velocity distributions. The axisymmetric case is considered where all cylinders have the same axis of symmetry with an arbitrary surface velocity field. The algorithm is applied to solve for scattering from rigid cylinders with hemispherical endcaps. Numerical results are presented for different two- or three-cylinder configurations with a plane wave incident from various directions. The dependence of the scattered field on the distance between two identical cylinders is examined as well as scattering from one large and one small cylinder.
Simulation of drop dynamics in an acoustic positioning chamber
Authors: Min Shermann L. , Holt R. Glynn , Apfel Robert E.
Published: October 2005

To support experiments scheduled for the First United States Microgravity Laboratory (USML-1) shuttle mission, experimental and computer simulation methods have been developed which allow ground-based investigation of the translational, rotational, and vibrational motions of single and dual liquid drops in an external acoustic field in a microgravity environment. The acoustic fields used are the 3-D orthogonal resonant modes of a rectangular chamber. Hardware and software development are described in detail. Results for the translation of single and dual drops are presented, and semi-automated schemes for controlled translation are proposed, tested, and evaluated.
Sonoluminescence and bubble dynamics for a single, stable, cavitation bubble
Authors: Gaitan D. Felipe , Crum Lawrence A. , Church Charles C. , Roy Ronald A.
Published: October 2005

High-amplitude radial pulsations of a single gas bubble in several glycerine and water mixtures have been observed in an acoustic stationary wave system at acoustic pressure amplitudes on the order of 150 kPa (1.5 atm) at 21–25 kHz. Sonoluminescence (SL), a phenomenon generally attributed to the high temperatures generated during the collapse of cavitation bubbles, was observed as short light pulses occurring once every acoustic period. These emissions can be seen to originate at the geometric center of the bubble when observed through a microscope. It was observed that the light emissions occurred simultaneously with the bubble collapse. Using a laser scattering technique, experimental radius-time curves have been obtained which confirm the absence of surface waves, which are expected at pressure amplitudes above 100 kPa. [S. Horsburgh, Ph.D. dissertation, University of Mississippi (1990)]. Also from these radius-time curves, measurements of the pulsation amplitude, the timing of the major bubble collapse, and the number of rebounds were made and compared with several theories. The implications of this research on the current understanding of cavitation related phenomena such as rectified diffusion, surface wave excitation, and sonoluminescence are discussed.
Examination of three-dimensional effects using a propagation model with azimuth-coupling capability (FOR3D)
Authors: Lee Ding , Botseas George , Siegmann William L.
Published: October 2005

A three-dimensional wave propagation model of parabolic approximation type (FOR3D) is used to examine 3-D ocean environmental variations. The background theory and characteristics of the model are reviewed briefly. Propagation situations that are classified as 3-D, N×2-D, and 2-D are described in connection with FOR3D and are interpreted in several ways. An analytic exact solution is used to demonstrate the model’s accuracy and its capability for treating fully 3-D propagation, when coupling exists between solutions in adjacent vertical planes of constant azimuth. It is also employed to illustrate a procedure for using approximate conditions at vertical side boundaries in a 3-D calculation. An application is made to an Atlantic Ocean shelf-slope environment with realistic bottom topographic variations and sound-speed profiles. The occurrence of significant azimuthal coupling is demonstrated in propagation loss versus range curves. It follows that, while the N×2-D approximation of no azimuthal coupling is useful in many situations, not all 3-D ocean acoustics problems can be adequately solved without a fully 3-D propagation model.
Waveform inversion for the geoacoustic parameters of the ocean bottom
Authors: Rajan Subramaniam D.
Published: October 2005

The geoacoustic properties of ocean sediments in deep water environments are important parameters necessary to predict low-frequency acoustic fields in the water column. A full wave method for obtaining the geoacoustic parameters from the acoustic field measured as a function of range with a cw source is presented. By assuming horizontal stratification, the unknown geoacoustic parameters are reduced to functions of one variable, i.e., depth. The problem of estimating the geoacoustic properties of the ocean floor is then cast as a parameter estimation problem in which a cost function φ(m), where m is a vector containing the unknown parameters, is minimized. This problem is then solved using a nonlinear optimization algorithm. This algorithm requires the determination of the derivative ∂φ/∂m. For a fluid bottom model an efficient algorithm for obtaining these partial derivatives is presented. The performance of the inversion algorithm is studied using noise free and noisy synthetic data. These inversions are carried out using the complex pressure field and the magnitude of the field as data. For the noise-free case, both approaches yield estimates close to the true value.

In the case of noisy data, inversions carried out using the magnitude of the pressure field as data do not perform as well as inversions where the data are the complex pressure field. However, in both cases the algorithm is stable. The effect of modeling errors on the estimates is studied and it is shown that even small errors in source/receiver location lead to significant errors in the estimates. The effect of modeling the sediment as a fluid on the estimation of its geoacoustic properties is studied. In the case where the sediment shear speed is much smaller than compressional wave speed, the fluid approximation has no significant effect on the estimate of the compressional wave speeds. On the other hand, if the shear speed is such that considerable conversion exists, the fluid bottom model leads to a poor estimate of the compressional wave speed. In both cases the estimates of compressional wave attenuation and density are significantly affected by the fluid approximation. Finally this method is applied to data obtained in a field experiment and an estimate of the compressional wave speed profile in the sediment layers is obtained. This result is compared with the model obtained by iteration of forward models [G. V. Frisk et al., J. Acoust. Soc. Am. 80, 591–600 (1986)].
Power-law relationships between the dependence of ultrasonic attenuation on wavelength and the grain size distribution
Authors: Nicoletti Denise , Bilgutay Nihat , Onaral Banu
Published: October 2005

Grain size is one of the factors that influence mechanical properties of metals like strength and fracture toughness. Ultrasonic waves propagating in polycrystalline materials are subject to attenuation dominated by grain boundary scattering. The importance of grain size estimation for industrial applications warrants the investigation of alternative methods of nondestructive grain size determination. Analysis of the power-law behavior of ultrasonic attenuation experimental data is used to link the wavelength dependence of the attenuation coefficient directly to the grain size distribution. The outcome is a simple relationship between the power law that describes the grain size distribution and the power-law dependence of attenuation on wavelength. Careful attention is given to the limitations in terms of a practical grain size distribution with finite limits. Two types of measurements are presented to verify the theoretical development: grain size distribution and ultrasonic attenuation. Nickel samples were prepared using three different annealing durations. The attenuation exponent is experimentally shown to be an appropriate nondestructive measurement of the grain size distribution exponent.
Test of a model of auditory object formation using intensity and interaural time difference discrimination
Authors: Woods William S. , Colburn H. Steven
Published: October 2005

A model of auditory object formation and an experimental evaluation of the model are described. Specifically, predictions for intensity discrimination and interaural time difference discrimination for the central component of a three-component harmonic complex are evaluated empirically. The onset time of the central, target component is varied relative to the onset times of the remaining, interferer components in order to vary the degree of fusion (versus perceptual segregation) of the target and the interferers. The model, which is based on the idea of attenuation of the components in the nonattended auditory image (in the case of segregated images), predicts lower sensitivity to information at the target component for the fused versus segregated target, and equal sensitivities for completely segregated targets and targets presented in isolation. Results are presented for four subjects with component frequencies of 400, 600, and 800 Hz and with onset time differences of 0 or 250 ms. The target duration was always 100 ms and offset times were the same for all components. The subjective results were as expected, with synchronous onsets yielding one sound object, and asynchrony of the central component yielding two sound objects. Also, the empirical results on interference in the synchronous case were in qualitative agreement with the above predictions. However, significantly more interference was found than was predicted for both synchronous and asynchronous conditions. In fact, the amount of interference found contradicts the simple attenuation model of object formation.
Controlling changes in vocal tract resistance
Authors: Warren Donald W. , Rochet Anne Putnam , Dalston Rodger M. , Mayo Robert
Published: October 2005

There is some evidence that speech aerodynamics follows the rules of a regulating system. The purpose of the present study was to assess how the speech system manages perturbations that produce ‘‘errors’’ within the system. Three experimental approaches were used to evaluate the physiological responses to an imposed change in airway resistance. The first involved subjects with varying degrees of velopharyngeal inadequacy. The second and third approaches involved noncleft subjects whose airway was perturbed by bleed valves and bite blocks during consonant productions. The pressure-flow technique was used to measure aerodynamic variables associated with the production of test consonants. The results of this study provide additional evidence that the speech system actively responds to perturbations in ways that tend to minimize a change in consonant speech pressures. The degree of success in stabilizing pressures appears to reflect the capability of the system to use whatever articulatory and respiratory responses are available.
Relative timing characteristics of hearing-impaired speakers
Authors: Robb Michael P. , Pang-Ching Glenn K.
Published: October 2005

Speech duration characteristics of phrase-level utterances produced by 26 severely and profoundly hearing-impaired adults were examined acoustically using relative timing measures. The measures were then compared to the same utterances produced by 13 normal-hearing adults. Although absolute speech durations of the hearing-impaired subjects were significantly longer than their normal-hearing counterparts, relative timing did not differ between groups. Findings are discussed in relation to the biological constraint hypothesis associated with speech timing, as well as the role of auditory feedback in models of speech production.
Speech of cochlear implant patients: A longitudinal study of vowel production
Authors: Perkell Joseph , Lane Harlan , Svirsky Mario , Webster Jane
Published: October 2005

Acoustic parameters were measured for vowels spoken in /hVd/ context by four postlingually deafened recipients of multichannel (Ineraid) cochlear implants. Three of the subjects became totally deaf in adulthood after varying periods of partial hearing loss; the fourth became totally deaf at age four. The subjects received different degrees of perceptual benefit from the prosthesis. Recordings were made before, and at intervals following speech processor activation. The measured parameters included F1, F2, F0, SPL, duration, and amplitude difference between the first two harmonic peaks in the log magnitude spectrum (H1–H2). Numerous changes in parameter values were observed from pre- to post-implant, with differences among subjects. Many changes, but not all, were in the direction of normative data, and most changes were consistent with hypotheses about relations among the parameters. Some of the changes tended to enhance phonemic contrasts; others had the opposite effect. For three subjects, H1–H2 changed in a direction consistent with measurements of their average air flow when reading; that relation was more complex for the fourth subject. The results are interpreted with respect to: characteristics of the individual subjects, including vowel identification scores; mechanical interactions among glottal and supraglottal articulations; and hypotheses about the role of auditory feedback in the control of speech production. Almost all the observed differences could be attributed to changes in the average settings of speaking rate, F0 and SPL, which presumably can be perceived without the need for spectral place information. Some observed F2 realignment may be attributable to the reception of spectral cues.
Theoretical and experimental study of a fiber optic microphone
Authors: Hu Andong , Cuomo Frank W. , Zuckerwar Allan J.
Published: October 2005

Modifications to condenser microphone theory yield new expressions for the membrane deflections at its center, which provide the basic theory for the fiber optic microphone. The theoretical analysis for the membrane amplitude and the phase response of the fiber optic microphone is given in detail in terms of its basic geometrical quantities. A relevant extension to the original concepts of the optical microphone includes the addition of a backplate with holes similar in design to present condenser microphone technology. This approach generates improved damping characteristics and extended frequency response that were not previously considered. The construction and testing of the improved optical fiber microphone provide experimental data that are in good agreement with the theoretical analysis.
Frequency analysis of sound radiation from an impact-excited plate
Authors: Takahashi D.
Published: October 2005

Transient sound radiation from a plate of infinite extent excited by a transverse impact of an elastic sphere is analyzed theoretically. An analytical expression predicting the sound pressure in the frequency domain is obtained with a reasonably simple form. The expression includes two terms, which can be evaluated separately, one of which is the term for calculating the radiation characteristics of the plate and another which is the term for the impact force spectrum. The radiated energy spectrum, which may be of great importance and practically useful for assessing the radiation problem of an impact-excited plate, is calculated by integrating the energy flow over a hemisphere of an arbitrary radius. It is shown by numerical results computed for the frequency spectrum, that an almost linear relation between the impact velocity and the generated sound pressure exists and that the critical frequency for coincidence may be an important factor for the impact problem in the same way as is seen in the harmonic steady-state case.
Dynamic response of laminated orthotropic spherical shells
Authors: Narasimhan M. C.
Published: October 2005

Dynamic response of laminated orthotropic spherical shells under axisymmetric dynamic load is investigated. The shell is assumed to be composed of layers of orthotropic materials whose principal material directions coincide with the shell curvature directions. The motion of the shell is described by a displacement field so as to include the effects of transverse shear deformation. Three coupled differential equations in terms of three generalized displacements at a point of the shell reference surface are written neglecting the rotatary inertia effects. These equations are then discretized in the time domain using the unconditionally stable Newmark-β integration scheme. The time discretized equations at any time step are solved by the method of global interior collocation at zeros of a Chebyshev polynomial of suitable order. Numerical results are presented to show the efficacy of the method. Results of parametric studies are presented to bring out the effects of the opening angle, material orthotropy, and shear deformation on the transient response.
Estimation of the spherical coordinates of multiple broadband targets via adaptive beamforming and nonlinear least squares
Authors: Ziomek Lawrence J. , Breckenridge Richard P.
Published: October 2005

Computer simulation studies of a frequency domain adaptive beamforming algorithm for planar arrays are presented. The algorithm is a modified, complex, least-mean-square (LMS) adaptive algorithm that provides estimates of the spherical coordinates (i.e., range, depression angle, and bearing angle) of multiple broadband targets in both the near-field and far-field regions of a planar array. Computer simulation results comparing the average range, depression angle, and bearing angle estimation errors as a function of the input signal-to-noise ratio (SNR) at a single element in the array, range (near field and far field), and harmonic number (frequency) are presented.
Pulse waveform recovery in a reverberant condition
Authors: Tohyama Mikio , Lyon Richard H. , Koike Tsunehiko
Published: October 2005

The phase trend of a transfer function (TF) has a nearly constant group delay in a reverberant sound field under high modal overlap conditions. This phase trend is robust and predictable from the reverberation time of a system. Inverse filtering for waveform recovery, however, is still a problem because of the nonminimum phase property of the TF. This paper proposes a method for source waveform recovery in a reverberant space. An impulsive source waveform can be recovered from a reverberant response by inverse filtering the minimum phase part of a reverberant TF. The minimum phase part is created by simply taking the absolute value of the group delay. The value of using exponential windowing waveform recovery is also discussed.
A new technique for measuring spectral shape discrimination
Authors: Kidd Gerald , Mason Christine R.
Published: October 2005

A new technique is described for studying the ability of listeners to discriminate between sounds on the basis of spectral shape, a process called ‘‘auditory profile analysis.’’ The advantage of the technique is that it reduces the range of the random rove in level necessary to provide a specified limit on the performance which listeners could achieve by ‘‘level detection;’’ that is, by employing a detection strategy based solely on comparisons of stimulus level. Thresholds were measured for the just-discriminable ‘‘ripple’’ (a pattern of alternating intensity increments and decrements) in an equal-amplitude, multitone reference spectrum for a group of normal-hearing listeners. Broadband, high-pass and low-pass filtered conditions were tested. The results indicated that the thresholds obtained using the new technique were well below the lowest level achievable by level detection (referred to as the ‘‘level-detection limit’’) in all conditions using a 20-dB random within-trial rove in overall level. The lowest threshold occurred for the broadband stimulus while the highest threshold was observed for the most extreme high-pass filtered condition. The new technique appears to be well-suited for study of profile analysis in hearing-impaired listeners where stimulus bandwidth and rove range are limited.
Overshoot in normal-hearing and hearing-impaired subjects
Authors: Bacon Sid P. , Takahashi Gail A.
Published: October 2005

Overshoot was measured in both ears of four subjects with normal hearing and in five subjects with permanent, sensorineural hearing loss (two with a unilateral loss). The masker was a 400-ms broadband noise presented at a spectrum level of 20, 30, or 40 dB SPL. The signal was a 10-ms sinusoid presented 1 or 195 ms after the onset of the masker. Signal frequency was 1.0 or 4.0 kHz, which placed the signal in a region of normal (1.0 kHz) or impaired (4.0 kHz) absolute sensitivity for the impaired ears. For the normal-hearing subjects, the effects of signal frequency and masker level were similar to those published previously. In particular, overshoot was larger at 4.0 than at 1.0 kHz, and overshoot at 4.0 kHz tended to decrease with increasing masker level. At 4.0 kHz, overshoot values were significantly larger in the normal ears: Maximum values ranged from about 7–26 dB in the normal ears, but were always less than 5 dB in the impaired ears. The smaller overshoot values resulted from the fact that thresholds in the short-delay condition were considerably better in the hearing-impaired subjects than in the normal-hearing subjects. At 1.0 kHz, overshoot values for the two groups of subjects more or less overlapped. The results suggest that permanent, sensorineural hearing loss disrupts the mechanisms responsible for a large overshoot effect.
Flexure waves in elastic rods
Authors: Coleman Bernard D. , Dill Ellis H.
Published: October 2005

The order-1 theory of the dynamics of homogeneous elastic rods is treated with the emphasis on twist-free bending motions of inextensible rods. Various forms of the governing equations for such planar motions are presented, and their traveling wave solutions are shown to result in curves of the same form as those in Euler’s theory of equilibrium configurations. Traveling waves are called subsonic or supersonic in accord with whether their speed is less than or greater than (E/ρ)1/2 with E the tensile modulus and ρ the density. The solitary traveling waves are loops and are given by elementary functions. At each prescribed level of tension below a critical value, for both subsonic and supersonic waves, the larger the loop the faster the wave. The periodic traveling waves, both with and without inflexion points, are given by elliptic functions and integrals. Small amplitude sinusoidal waves are a limiting case of inflexional waves. The solitary waves are obtainable as appropriate limits of both inflexional and noninflexional waves. Although, in general, traveling waves are motions of rods of infinite length, there are traveling waves that are possible planar modes of motion for rods of finite length with joined ends. A rod with such a traveling wave forms a figure eight in the inflexional case and a circular ring in the noninflexional case.
Transient response of thick rectangular bars subjected to transverse elastic impact
Authors: Lin Yiching , Sansalone Mary
Published: October 2005

The objective of the research presented in this paper was to study the transient response of thick rectangular bars subjected to transverse elastic point impact. It is shown that the transient response is composed of a number of resonant frequencies caused by cross-sectional modes of vibration. The individual modes and their corresponding natural frequencies were determined using plane-strain, finite-element models of rectangular cross sections. The effect of the cross-section aspect (depth/width) ratio on the natural frequencies is shown. Three-dimensional, finite-element models of rectangular bars were analyzed to determine the transient response caused by transverse point impact. To verify the results obtained from the numerical studies, experimental studies were performed on rectangular bars with aspect ratios of 0.60, 0.75, 1.33, and 1.67. The bars used in the experimental study were representative of full-scale concrete beams and columns—typical barlike structural elements. Excellent agreement was obtained between the numerical and experimental results. This paper is the second in a series of three papers aimed at understanding the transient elastic impact response of solid bars and bars containing flaws. Together these papers establish the basis for the use of the impact-echo method (a test method based on the use of transient point impact) for nondestructive testing of barlike structural elements.
Parametric analysis of the power flow on an L-shaped plate using a mobility power flow approach
Authors: Cuschieri J. M.
Published: October 2005

In an earlier paper [J. M. Cuschieri, J. Acoust. Soc. Am. 87, 1159–1165 (1990)], the coupled response of two identical plate structures, determined using a mobility power flow (MPF) approach is presented. The plates’ responses are described in terms of the vibrational power input and transfer between the two plates. In this present paper, the MPF analysis for the vibrational response, power input, and transfer is presented for two coupled plates with arbitrary characteristics. Using the results from this analysis, a parametric evaluation of the plates’ responses is presented for changes in the plates’ structural parameters, which include different areas, thicknesses, materials, and structural damping loss factors. In the case of the structural damping, equal as well as different damping of the two plates are investigated. Furthermore, the response of the two plates for different excitation locations is included in the parametric evaluation. To minimize the number of results that are presented the source plate characteristics are kept constant except in the damping analysis. The results of the parametric analysis are used to determine the most critical parameters that influence the flow of vibrational power between the two coupled plates. The results obtained from the MPF approach are compared to results obtained using a statistical energy analysis (SEA) approach. The significance of the power flow results are discussed together with a discussion and a comparison between the SEA results and the MPF results.
Mismatch negativity evoked potential to categorically perceived speech stimuli.
Authors: Sharma Anu , Kraus Nina , McGee Therese J. , Carrell Thomas D. , Nicol Trent G.
Published: October 2005

Categorical perception of certain speech and speech-like sounds has been critical to models of speech perception for decades. Furthermore, refining our knowledge of the stimulus and task characteristics that lead to categorical perception continues to be an important part of research in speech perception. Auditory evoked potentials (AEPs) have the capability of providing new perspectives on this important phenomenon. The mismatch negativity (MMN) AEP is elicited in response to a physically deviant stimulus occurring in a series of standard stimuli [Näätänen etal., Acta Psychol. 42, 313–329 (1978)]. The MMN has been shown to be sensitive to fine acoustic differences and was used in the present study to examine a stimulus continuum that typically leads to categorical perception. The primary auditory cortex is thought to be a major source contributing to the generation of the MMN. In the present experiment a stimulus continuum ranging from /da/ to /ga/ was synthesized by varying the frequencies of F2 and F3. An identification task showed the expected steep slope in the identification function along this continuum, indicating that they were perceived categorically. An electrophysiologic index of discrimination was obtained by recording the MMN in adults to stimulus pairs, having equal acoustic differences, within and across categories. The MMN was observed in all subjects and was the same size both across and within categories. That is, the MMN indicated equal discrimination both across and within categories. These results suggest that the MMN reflects the processing of auditory aspects of these speech-like signals, but not processing into phonetic categories.