bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental aspects of the production of velar stop consonants
Authors: Lieberman Philip , Sereno Joan A.
Published: October 2005

This experiment examines vowel context effects. In adults, the general spectral characteristics of velar stop consonants vary as a function of vowel context. A velar stop preceding a front vowel has a predominant spectral peak in the mid-frequency region whereas a velar stop preceding a back or central vowel has a spectral peak in the low-frequency region and a secondary spectral peak in the high-frequency region. In the present experiment, CV syllables ([ki], [ka]) were produced by adults and children. Short time spectra were computed for each stimulus. The results indicate that the adult stimuli, as expected, show significant vowel context effects. In the child data, however, the differences for the velar stops preceding front and back vowels are not always present. A perceptual analysis was then conducted using the aperiodic portion of the [ki] and [ka] syllables. These data show that the vowel context effects for adults are perceptually salient but that these cues are often not perceptible in the child stimuli. The results arc discussed in terms of their implications for language learning.
Transmission intensity in shallow oceans, and implications for passive tracking
Authors: Robertson J. S. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

The behavior of incoherent total-field intensity is considered for a moving cw source in shallow water. The ocean channel is assumed isospeed, with a planar perfectly reflecting surface and a planar lossy bottom. The source is located at constant depth on a linear path, and the receiver is fixed on the bottom. An expression for incoherent total-field intensity is derived in terms of source-motion and environmental parameters. For a bottom with uniform loss per ray reflection, an approximation for intensity using special functions is developed and analyzed. The behavior of this novel approximation with respect to variations in source parameters such as range, depth, and speed, as well as bottom loss variations, suggests its usefulness for prediction of source motion. Two properties of the approximation, peak curvature and peak width, are selected as source motion descriptors. Both are shown to be relatively sensitive to changes in source parameters and insensitive to bottom loss variations. We apply our descriptors to an example, and discuss their use in supplementing existing passive tracking methods. [Work supported by ONR.]
Approximation of the dynamics of a towed sonar antenna using linear FIR filters
Authors: Brandenburg Wulf
Published: October 2005

In low-frequency sonar systems, long towed arrays are used to estimate target parameters like bearing etc. The standard method for bearing estimation is based on conventional beamforming. This procedure requires the knowledge of the sensor locations. Therefore, a point mechanical model for the dynamics of a towed array is developed, which is described in the Proceedings of the IEEE-ICASSP, 1984. These results show that the dynamics of a towed array can be approximated by linear systems with transfer functions given by polynomials (FIR filters). The advantage of this method is that the shape of the towed array can be easily estimated in real time by convolution while the tow ship is performing maneuvers. One needs the system functions which are only calculated once and then stored in a computer. For each point of the towed array there exists a different system function. The input of the system “towed array” is the course Φ0(t) of the towing ship at time t and the outputs are the directions Φi (t) of the tangential vectors at different points i = 1,…,N of the towed array. This method is very useful, for example, for adaptive beamforming or for evaluation of the sensitivity of the beam pattern to the two ship's maneuvers. Examples show that the approximation is valid for a wide range of parameters. This is also verified by measurements.
In situ optimal reshading of arrays with failed elements
Authors: Sherrill M. S. , Streit R. L.
Published: October 2005

An algorithm is presented which computes optimal weights for arbitrary linear arrays. The application of this algorithm to in situ optimal reshading of arrays with failed elements is discussed. It is shown that optimal reshading can often regain the original sidelobe level by slightly increasing the mainlobe beamwidth. Three examples are presented to illustrate the algorithm's effectiveness. Hardware and software issues are discussed. Execution time for a 25-element array is typically between 1 and 2 min on a HP9836C microcomputer.
Method for study of the three-dimensional beam patterns and directivity indices of volumetric arrays using a microcomputer
Authors: Greene David C.
Published: October 2005

PASCAL language computer programs are described which allow the calculation of the three-dimensional sensitivity patterns and directivity indices (DI's) of volumetric arrays of omnidirectional receivers steered to any direction in space. The method reads a disk file containing the array design (element positions and real and imaginary shading coefficients), responds to user inputs of frequency, beam-steer direction, and angular resolution (in colatitude and azimuth angles), and produces a disk file containing the response relative to that at the steered direction for each resolved element of solid angle. The output disk file is accessed by a separate program to plot selected beam patterns. The directivity index for the array at the specified frequency and steer direction is estimated by numerical integration and presented on the console. The number of receiving elements in the array and the resolution in solid angle are limited only by available memory (5-deg×5-deg resolution over all space on the author's implementation).
Very-high-resolution object imaging by CTFM airborne echo location
Authors: Kay Leslie , Anderson Christopher , Cusdin Michael J. , Sinton Julian
Published: October 2005

An ultrasonic unitary transducer array incorporating 60 independent radiating elements has produced a focused beam of airborne ultrasonic waves varying in wavelength from 1.5 to 3 mm as the frequency varied cyclically from 200 to 100 kHz. The focal region was digitally controlled in four radial steps within the range 0.3 to 0.6 m, and in 60-deg steps. Measurements showed the resolution in radial distance to agree closely with the theoretical limit of 1.6 times the mean wavelength of 2.25 mm. Azimuth resolution agreed well with the theoretical value when using an aperture of 150 mm and a focal distance of 0.3 to 0.6 m. This was measured to be 9 mm at a radial distance of 0.45 m. Resolution is here defined as the displacement necessary to reduce the peak intensity by 20 dB. The cross section of a 120-mm cylinder covered with corrugated paper to produce spaced specular reflections was imaged showing the resolution limits. The CTFM system was highly noise resistant compared with a pulse system having the same radial resolution. This is because to achieve an octave bandwidth, solid dielectric capacitance transducers are used. The maximum pulse power of approximately two cycles duration is therefore limited to the maximum continuous wave power as used in the CTFM system.
Ultrasonics in manufacturing
Authors: Knight J. A. G. , Pomeroy S. C. , Beurle R. L.
Published: October 2005

Research was initiated at the University of Nottingham, UK in 1983 to develop ultrasonic sensor systems for flexible manufacturing. This research work, undertaken jointly by the departments of Production Engineering and Electrical Engineering, has developed into a research center for investigating the uses of ultrasonics in manufacturing. Industrial participation has been present from the inception of the research through a cooperating partner, Transfer Technology Ltd. The industrial contribution to the research is shortly to be enhanced through the formation of a “club” of industrial companies, all of which will commit resources, and in return will receive access to the research findings so as to be able to implement ultrasonics into manufacturing more effectively. The research to date has developed both single transducers and arrays to operate at frequencies up to 200 kHz in air. A computerized automatic test facility has been built for transducers. A range measuring system has been constructed utilizing two proprietary ranging systems interfaced to a microcomputer. The system operates between 130 mm and 10 m and has a range resolution of 0.05 mm at distances up to 500 mm. An ultrasonic imaging evaluation system has been built consisting of a dedicated multichannel acquisition system attached to a microcomputer. Image formation and analysis are performed in software. Further research involves the integration of ultrasonic information with simple binary vision information to obtain high resolution 3-D information.
Synchronization of spontaneous otoacoustic emissions and driven limit-cycle oscillators
Authors: Long Glenis R. , Tubis Arnold , Jones Kenneth
Published: October 2005

Spontaneous otoacoustic emissions (SOAE's) can be synchronized by external tones within a narrow frequency band characterized by a synchronization tuning curve [E. Zwicker and E. Schloth, J. Acoust. Soc. Am. 75, 1148–1154 (1984)]. Surrounding this range of synchronization is a region of unstable partial synchronization leading to amplitude fluctuations of the stimuli. Psychophysical synchronization threshold curves [D. T. Kemp, Scand. Audiol. Suppl. 9, 35–47 (1979)], based on an abrupt change in the percept of low-level stimuli near threshold microstructure, show similar tuning. These two types of synchronization tuning curves are compared in subjects with strong SOAE's and associated threshold microstructure. Simple models for these tuning curves are discussed in terms of driven limit-cycle oscillators. [Work supported by NIH.]
Auditory nonlinearities: A new approach in light of an active model
Authors: Caerou J. C. , Dolmazon J. M. , Shuplakov V. S.
Published: October 2005

A new model of ear which simulates the nonlinear behavior of the peripheral auditory system for real input sounds is described. The main assumption underlying the structure of the model is the presence of an active mechanism which works mainly near the resonance. The general structure of the model looks like classical lumped transmission line. Each cell has its own frequency resonance according to the coordinate-frequency correspondence observed along the basilar membrane. A nonlinear local feedback from the resistive element is mixed to the input signal in each cell. Such a circuit exhibits interesting results concerning, mainly, the evolution of selectivity with respect to the input signal level, two-tone suppression effects, and combination tones generation. The first experiments carried out by a computer simulation which uses a classical numerical method for resolution of a nonlinear differential equation system are presented. Tuning curves which show a decreasing Q factor when increasing the input level, and the results obtained with multifrequency component input signals, are presented.
Latency of otoacoustic emissions and ABR wave V using tone-burst stimuli
Authors: Neely Stephen T. , Norton Susan J. , Gorga Michael P. , Jesteadt Walt
Published: October 2005

Auditory brain stem responses (ABR) and otoacoustic emissions (OAE) were measured in normal-hearing subjects, using tone-borst stimuli. The measured latency of wave V can be characterized as the sum of two components: (1) a “mechanical” component which varies with both intensity and frequency; and (2) a “neural” component which is independent of intensity and frequency. The mechanical component can be viewed as the time it takes for the stimulus to reach its point of maximum displacement on the basilar membrane. The neural component can be thought of as the time between this mechanical event and the generation of wave V. The determinants of OAE latencies are not completely understood. Current theories suggest that OAE's are determined by cochlear mechanical properties and that their latencies should be twice the “forward” travel time to the cochlear place which responds best to a given frequency component. Using similar stimuli, the latency of the “mechanical” component of the ABR was compared to the latency of the OAE. The data are consistent with the “two-way” travel hypothesis. [Work supported by NINCDS.]
Noncontact ultrasonic gauging for industrial applications
Authors: Billings John K.
Published: October 2005

Ultrasonic arrays (UAI) have made advances in air-coupled, pulse-echo acoustic technology which permit noncontact gauging for many industrial applications. Noncontact ultrasonic dimensional gauging applications include measurement of thickness, distance, position, perpendicularity, shape, and orientation. Accuracy is the greater of plus or minus 0.1% of range or 0.001 in. over a dynamic range of 0.2 to 23.999 in. UAI's accuracy improvement is due to the development of an advanced-technology capacitive transducer that transmits and receives a high-frequency unambiguous sound pulse. In addition, environmental factors that affect the speed of sound in air have been largely eliminated through extensive signal processing and an external reference that recalibrates target data during each sample. The microprocessor-based controller and external reference are also used for automatic gain control thereby preserving the integrity of the waveform over time and in varying environments. The controller provides communications with other devices via RS 232 and RS 422 serial data ports as well as multiplexing multiple transducer channels. On-board software permits the selection of sample rates for rapidly moving targets, high and low limits, relay configuration, echo selection, target filtering, and diagnostics. Both 4- to 20-mA current and 0- to 10-V dc current are available for control functions. Other requirements for gauging include the use of parabolic mirrors for focusing, tilting mirrors for sound directional changes, and shaded apertures for surface detail in cluttered backgrounds.
Ultrasonic study of concentrated coal-water slurries
Authors: Gultepe M. A. Barrett , Gultepe M. E. , Yeager E.
Published: October 2005

The use of ultrasonic absorption measurements as a diagnostic tool for monitoring the particle size of coal-water slurries has been suggested by M. C. Davis [J. Acoust. Soc. Am. 65, 387 (1979)]. The present paper reports some experimental data obtained from ultrasonic absorption and velocity measurements on electrostatically and sterically stabilized coal-water slurries of average particle diameters of 5 and 50 μ. Ultrasonic absorption measurements were made in the frequency range of 1 to 25 MHz for 1 °C to 80 °C. The results are compared with various explicit expressions for heat conduction, viscous drag losses, and scattering of sound by particles. The experimental absorption was consistently higher than that predicted, even when allowing for the averaging effect era wide particle size distribution. The experimental results also indicate that velocity measurements in a coal-water slurry have the potential of becoming another possible diagnostic tool along with attenuation measurements. [Work partially supported by ONR.]
Sound wave preparation through a polydispersion of rigid particles
Authors: Margulies Timothy S. , Schwarz W. H.
Published: October 2005

The theory for infinitesimal, planar-sound wave propagation in a dilute, polydispersion of rigid spherical particles suspended in a viscoelastic fluid has been developed. Particle-fluid interaction terms for both momentum and heat transfer are taken into account in the linearized average continuum equations. General results are obtained in the form of a biquadratic characteristic equation for the complex propagation constant χ = (α + iω/c), where α is the attenuation coefficient, c is the phase speed of the progressive wave, and ω is the angular frequency. These results represent a generalization of those previously derived by S. Temkin and R. A. Dobbins [J. Acoust. Soc. Am. 40, 317 (1966)] to viscoelastic fluids. Also, the drag force on each particle includes modified Stokes drag, added mass, and Basset (time history) terms appropriate for a simple fluid with memory. Computer simulations have been made indicating the dependence of the observables, α and c, upon physical properties, such as the acoustic viscosity, particle size/distribution, and solid volume fraction, as well as, upon the drag forces modeled. Similarities and discrepancies among results of different theories, for example those by Urick and Allegra-Hawley, are discussed using available experimental measurements.
Anisotropic wave propagation in crystals: Quasilongitudinal and quasitransverse waves
Authors: Rao G. Kameswara
Published: October 2005

We can propagate elastic waves in any crystal plane along the principal directions as well as along certain specific directions as purely longitudinal and purely transverse waves. [F. E. Borgnis, Phys. Rev. 98, 1000–1005 (1955)]. In some cases, the waves deviate from their pure nature and such waves are called quasilongitudinal and quasitransverse waves, in which the displacement direction does not exactly coincide with the propagation direction. In the case of orthorhombic crystals, for a wave propagating in the {110}, planes an expression for the deviation angle 0 is derived in terms of the elastic constants and the direction cosines of the propagation vector. The deviation angles have been calculated for 11 crystals. In the case of orthorhombic crystals, the lattice parameters are designated with the convention b > a > c. [W. R. Cook, Jr. and H. Jaffe, Acta Cryst. 10, 705 (1957)]. But a survey of the crystallographic data shows that this has not been so. Only in the case of 4 crystals out of the 11, does the crystallographic data fit the b > a > c convention. This necessitates the reconsideration of the elastic constants data for the purpose of rationalization. A knowledge of the deviation angles enables one to assess the order of accuracy of the experimentally determined elastic constants of the type cij (i ≠ j). The order of accuracy of the cij (i ≠ j) is of particular importance in calculating the contribution due to stress birefringence or stress optical path retardation in the determination of the photoelastic and electro-optic constants of the crystals.
Criteria and constraints of modeling the perception of pitch
Authors: Terhardt Ernst
Published: October 2005

The vast amount of data and observations relevant to the perception of pitch has grown through many decades and at first did not seem to support ease of modeling; it rather elucidated that pitch modeling is much more complex than just measuring “the fundamental frequency” in either the frequency or time domain. While the concept of auditory spectrum analysis is enormously helpful and successful in many respects, it failed to provide a direct explanation of the pitch of many ordinary sounds such as speech and music. Various time-domain explanations, on the other hand, proved unsatisfactory as well. In the late 1960s the conclusion was drawn that modeling pitch perception requires careful inclusion, and combination, of signal-theoretical, psychophysical, and Gestalt-psychological methods. The present author's “virtual-pitch theory” was worked out on that line. As an additional significant outcome of the new approach, it turned out to be not quite just a pitch model, but reflects and illustrates significant general principles of auditory perception and, in particular, of music perception. Until present, that type of modeling has been successful and appears to be supported by more recent experimental findings. Thus critical reconsideration and analysis of its essentials, i.e., indispensable characteristics, structures, and parameters seems appropriate. Particular attention is paid to the characteristics of aural spectrum analysis, the dichotomy of spectral versus virtual pitch, and the question of learning processes. Some crucial phenomena are demonstrated using tape examples.
Informational masking in vowel sequences
Authors: Kewley-Port D. , Watson C. S. , Czerwinski M.
Published: October 2005

In a number of earlier studies, Watson and his colleagues have described various stimulus and training variables which determine the detectability and discriminability of single components within complex sequences of tones [e.g., J. Acoust. Soc. Am. 76, 1037–1044 (1984)]. A series of studies has begun to investigate whether, under the same conditions, similar discriminability will be observed for speech and nonspeech waveforms. Modeling a female talker, ten English vowels were synthesized at five durations (20–160 ms). Detectability of the vowels was studied using an adaptive tracking task. Large (20 dB) differences in thresholds were obtained among different vowels presented in isolation. Thresholds were then obtained for 40-ms vowels presented in ten-vowel sequences. In a high-uncertainty task, parameters previously shown to affect detection in tonal sequences similarly affected vowel detection. Vowels in initial or final position were detected most easily. Informational masking for vowels was observed to vary from 0 to 45 dB across subjects. At least for these preliminary experiments, the same mechanisms shown to underlie the perception of tonal sequences also appear to determine the processing of complex speech stimuli. [Supported by NINCDS and AFOSR.]
Spectral envelopes and perceptual target zones for consonants and vowels: Preliminary estimates
Authors: Miller James D. , Hawks John W.
Published: October 2005

Preliminary estimates of the sizes, shapes, and locations of perceptual target zones (PTZ) of ten vowels, six dipthongs, a twenty-nine consonants have been made. The PTZ's are defined as enclosed volumes in the space x = log(PF3/PF2), y = log(PF1/PR), and z = log(PF2/PF1), where PR is the perceptual reference in Hertz and PF1, PF2, and PF3 are the center frequencies of the perceptual formants. The perceptual formants are estimated from spectral envelopes as guided by rules for distinguishing burst-friction spectra and glottal-source spectra and for naming and numbering formants based on their logarithmic relations to the value of the reference. The estimation of PTZ's will be illustrated for at least one allophone from each of the following classes: vowels, diphthongs, approximates, nasals, voiceless fricatives, and voiced fricatives. These preliminary estimates indicate that PTZ's: (1) are large, thus encompassing a considerable range of spectral variants as might be associated with coarticulatory effects and articulatory style; (2) have irregularly shaped, abutting boundaries; and (3) for the most part, exhibit little overlap. [NINCDS grant R0 I-NS21994-01.]
The effects of similarity neighborhood structure on auditory word recognition
Authors: Luce Paul A.
Published: October 2005

The present study examined how the structure of similarity neighborhoods of spoken words affects auditory word recognition. Similarity neighborhoods were computed on phonetic transcriptions of approximately 20 000 words in an on-line version of Webster's pocket dictionary. Among the variables of interest were: (1) the density of the similarity neighborhood; (2) the frequencies of words within the neighborhood; and (3) the frequency of the target word itself. Nine-hundred and twenty-eight three-phoneme, monosyllabic words varying on each of these variables were presented at each of three signal-to-noise ratios for identification. In addition, confusion matrices were obtained for all initial and final consonants and vowels occurring in the 928 stimuli in order to account for basic differences in segmental confusability and intelligibility. The results will be discussed in terms of the combined effects of similarity neighborhood structure and segmental confusability on auditory word recognition. [Work supported by NIH grant No. NS-12179 to Indiana University.]
Perception and interpretation of English intonation by Arabs
Authors: Mitleb Fares
Published: October 2005

This paper outlines an experiment designed to assess Arab's perception and interpretation of English intonation. Subjects were 30 native Arabic speakers majoring in English. Test material was a set of 20 minimally paired sentences, differing in intonation only, or presenting the same intonation pattern twice, spoken on a tape by a native English speaker. The task was to decide whether the two sentences in each pair have the “same” or “different” intonation pattern and to assign meaning (s) of the provided glosses according to the previous judgement. The analysis of the responses indicates a clear hesitation in perceiving intonation and in assigning meaning to intonation patterns tested in this study. This hesitation, however, is not attributed to intonation interference; rather, it seems to be a result of faulty instructional process. English pronunciation is usually taught to second language learners with great emphasis on the segmental language units. Language learners usually preserve this knowledge when they are moved into suprasegmental situations. We thus propose that English pronunciation is to be introduced in suprasegmental units instead of segmental units.
Automatic target generation for vowels
Authors: Chang Hisao M. , Miller James D.
Published: October 2005

Research in phonetic recognition by computer is of interest because it may offer better performance than systems using larger-recognition units such as syllables or words. Among several techniques developed to model speech signals as phoneme sequences (e.g., hidden Markov models and other feature-based methods) is the phonetic-target model based on the auditory-perceptual theory of Miller [ASHA Reports 14 (1984)]. In it: (1) talker differences that mask acoustic phonetic correlates are minimized when incoming speech signals are represented as paths in a three-dimensional space, where X = log(P3/P2), Y = log(P1/R), and Z = log(P2/P1); and (2) phonetic targets defined in this space seem to be uniquely related to the acoustic patterns of phonelike elements. An automatic procedure generated three phonetic targets for the vowels /ɪ/, /ɛ/, and /ʌ/ from a set of training tokens in stop-vowel-stop format recorded from two male and two female talkers. When four new talkers were tested, a vowel recognition accuracy of about 98 % was attained. Additionally, a segmentation algorithm isolated the vocalic segments from the stop bursts with 100% accuracy. [NINCDS grant R01-NS21994-01.]
A further investigation of acoustic scattering from the sea surface
Authors: Nuetzel Bernd , Herwig Heinz , Monti Joseph M. , Koenigs Paul D.
Published: October 2005

The results from a recent sea surface acoustic scattering experiment, which was conducted in the North Sea, are presented with accompanying sea surface roughness parameters and subsurface bubble information. The acoustic data were obtained utilizing a high-resolution (narrow-beamwidth) pulsed parametric sonar transmitter and conventional receivers. Scattering strength values were obtained as a function of frequency (3–18 kHz) and grazing angle (10°–90°) for differing sea surface roughness and wind speed conditions. The mean scattering strength values illustrate a strong dependence on large and small scale sea surface roughness. Comparisons with theoretical and semiempirical models indicate the appropriateness of using composite roughness modeling theories.
A stochastic propagation and scattering operator for ocean propagation
Authors: Yang C. C. , McDaniel Suzanne T.
Published: October 2005

General properties of acoustic propagation and scattering in a stochastic open environment are investigated. In this study, the positions of the source and observation points can be arbitrary. Furthermore, these two points can be in relative motion. The most important factor of the ocean environment affecting wave propagation is the sound-speed profile. Also, because of the fine structure in temperature, stochastic fluctuations of the sound speed may exist along the paths of a sound wave. Therefore, effects from random scattering have to be taken into account. Because of the existence of the sound-speed profile in the ocean, more than one path may be drawn to connect the source and observation points. This multipath effect, including that due to the correlations among these paths, is fully discussed. To make computations feasible, the path integral technique is applied. [Work supported by ONR.]
A depth, range, and time probability distribution of intensity for wave propagation in random media
Authors: Ewart T. E.
Published: October 2005

The second moment of intensity as a function of depth, range, and time for WPRM can be modeled in terms of a space-time autocorrelation function, a scattering strength parameter γ, and a scaled range X. The higher moments have not been predicted for all λ and X; however, it is generally accepted that the intensity moments are lognormal at small X and exponential at large X. The generalized gamma distribution function (GGDF) [E. W. Stacy, Ann. Math. Star. 33, 1187 (1962)] forms a large class that includes the lognormal and the exponential pdf's. It is proposed that the GGDF can model the probability distributions of intensity in forward scattering over wide ranges in y and X. The temporal intensity fluctuations measured during MATE and depth-range results from Monte-Carlo simulations of WPRM for a medium with a power law autocorrelation function have been used to test the proposition. The “goodness of fit” of the GGDF's fitted to those data sets, and the benefits of using distribution modeling rather than intensity moment will be discussed. The results are convincing; it remains a nontrivial task to test the hypothesis theoretically. [Supported by ONR code 4250A.]
Evoked potential asymmetries and behavioral responses to consonant-vowel stimuli presented dichotically and diotically
Authors: Sammeth Carol A. , Barry S. Joseph
Published: October 2005

Cortical auditory-evoked potentials (AEP's) were recorded simultaneously with the collection of behavioral responses to consonant-vowel stimuli presented both dichotically and diotically in a group of 16 right-handed normal females. During dichotic listening, the mean N1-P2 component of the AEP's recorded over the temporal region of the left hemisphere was found to be significantly larger in amplitude than the mean recorded over the homologous area of the right hemisphere. No significant amplitude differences were found for any AEP component during diotic listening. The latencies of AEP components revealed no systematic trend across hemispheres during either dichotic or diotic listening. The mean amplitude of N1, and the mean peak-to-peak amplitudes of P1 and N1 and N1-P2 were significantly larger over the right hemisphere during dichotic listening than during diotic listening, a result opposite to that expected if suppression of right hemisphere activity had occurred during dichotic testing. Correlation analyses revealed no significant relationships between hemispheric differences in AEP's, a measure of strength of handedness, and a measure of right-ear advantage during dichotic listening.
The measurement of auditory brain stem responses in the presence of high-pass and notch noise maskers
Authors: Prieve Beth A. , Abbas Paul J.
Published: October 2005

The auditory brain stem response (ABR) was recorded from hearing-impaired persons having steeply sloping, high-frequency, sensorineural hearing loss and normal-hearing persons. Tone bursts and clicks were presented to all subjects in quiet and in the presence of either a high-passed or a 1-oct, notched-noise masker. The maskers were high passed/centered at 2 and 4 kHz. For normal-hearing subjects, the latency of wave V was greater for responses to masked stimuli than for unmasked stimuli. An increase in wave V latency was also seen for masked tone bursts or to clicks presented in the 2-kHz passed/centered masker in the hearing-impaired subjects. When clicks were presented to the hearing-impaired subjects in the presence of a high-pass masker with a 4-kHz cutoff, wave V latency increased. However, when presented in the presence of a notch-noise masker centered at 4 kHz, latency decreased. These findings suggest that the response to clicks in impaired ears may arise from neurons more apical than those in unimpaired ears.
Analysis of high-frequency cw tones propagated in the Arctic Ocean
Authors: Catipovic Josko , Baggeroer Arthur B.
Published: October 2005

During the marginal ice zone experiment (MIZEX), measurements were made of the fluctuating phase and amplitude of a densely spaced set of tones centered around 50 kHz. Eight tones were transmitted simultaneously; the intertone spacing varied from 50 Hz to 1 kHz. The transmitter and receiver were located 10 m below the surface, immediately below the ice. The propagation path was approximately 1.5 km long. The received tones show extensive fading at time rates corresponding to mean drift which produces a nearly constant phase rate; ice motion at approximately 1/10 Hz; and internal waves at higher rates. The tone fading is nearly frequency independent at lower rates, but has a frequency correlation of several hundred Hertz at fade rates of approximately 1 s. The various rates of fluctuation are separated in the analysis to identify the generation mechanism. Envelope and phase amplitude analysis indicate a fully saturated path with most of the effect arising from the higher fluctuation rate. Time-frequency correlation of about 1 s and 300 Hz dominate. For underwater communications these results show that phase coherence at these frequencies is difficult to attain even at close ranges, and that the time-variant channel behavior requires either high coding levels or adaptive code selection or decoding for useful data transmission.
Vibrotactile pattern recognition
Authors: Craig James C. , Evans Paul M.
Published: October 2005

Several factors influence the identification of complex vibrotactile patterns, e.g., masking, attention, and experience. Two processes that may underlie backward masking are temporal integration and interruption. The types of target patterns used in previous studies have made it difficult to separate these two processes. The results of a study using a specially designed set of patterns that varied in the number of line segments they contained and had no intracharacter redundancy suggest that temporal integration is a major factor in masking. Masking can be reduced by spatially separating two patterns, e.g., presenting one to the index and one to the middle finger. This manipulation improves identification of a single pattern; however, identification of both patterns is difficult. Subjects appear to have difficulty in attending to two patterns presented to two fingers simultaneously. This difficulty is greatly reduced if two fingers on opposite hands are used. It has also been shown that experience improves vibrotactile pattern identification. However, comparisons of blind users of a vibrotactile reading aid with sighted subjects receiving training in the laboratory suggest that major changes in performance result from modest exposure to tactile patterns. Improvement appears to result from increased tactile sensitivity and from learning specific features of patterns.
Frequency resolution via single and multichannel tactile transforms
Authors: Hnath Terry , Boothroyd Arthur , Hanin Laurie
Published: October 2005

Simple synthetic intonation contours, consisting of 100 ms of constant frequency followed by a 100-ms linear frequency fall, were presented to five normal subjects via two vibrotactile transforms: a single channel (temporal) transform, and a multichannel (spatial) transform. Channel spacing in the multichannel transform was 1 cm. Thresholds for the detection of frequency falls were measured using a three interval, forced-choice, adaptive procedure. With the single-channel transform, mean thresholds on the index finger were 0.3 and 0.4 oct for reference frequencies of 100 and 200 Hz, respectively. On the soft tissues of the forearm, however, the threshold for a reference frequency of 200 Hz was approximately 2 oct. The multichannel transform provided thresholds of one channel on the forearm. In an eight-channel display of voice fundamental, a spatial resolution of one channel represents a frequency resolution of roughly 0.3 oct, which is equivalent to that of a single-channel display on the index finger. Improved resolution can be obtained by increasing the number of channels. [Research funded by NIH grant No. 17764.]
An order effect in the discriminability of pulse train sequences
Authors: Tillmann Hans G. , Piroth Hans Georg
Published: October 2005

During investigations of basic mechanisms for tactile speech transmission, an order effect was revealed in the discriminability of electrocutaneous pulse train sequences. Experiment 1 uses a 2IAX-one-step discrimination test to show that tactile sequences of nine pulses with a duration of 24 ms each and an interpulse interval of 15, 35, and 55 ms, respectively, are discriminated better if the sequence with the greater IPI is presented first. In an all-step discrimination test with a constant target (IPI = 35 ms), the extent of the effect could be determined (experiment 2): Of two sequences presented as a pair, the second is judged to have the same IPI as the first if it exceeds IPI of the first by 13.9%. Experiment 3 shows that the effect can be reproduced in the auditory mode with analogously constructed sinusoidal pulse trains. On the other hand, the effect breaks down when pulse train sequences of long and constant durations (2.5 s) are used (experiment 4). As an explanation an analog to the “final lengthening” phenomenon in speech is proposed, as well as an explanation in terms of “time order error.”
Auditory and oral tactile sensory system interactions: Magnitude estimation and cross-modality matching
Authors: Fucci Donald , Petrosino Linda , Harris Daniel
Published: October 2005

Research that has been done on the interaction of auditory and oral tactile sensory systems has involved experimental techniques intended to disrupt one or both sensory modalities. An instrumentation system has been designed to investigate the relationship between auditory and oral tactile sensory processes without disruption of one or both sensory channels. This instrumentation can be employed to obtain judgments of auditory and oral tactile sensation magnitudes by the psychophysical scaling methods of magnitude estimation and cross-modality matching. Magnitude estimation scaling requires the subject to assign numbers to subjectively match the intensities of different stimulus levels presented by the experimenter. Cross-modality matching requires the subject to adjust the stimulus intensities applied to one sensory modality to match those applied to another sensory modality by the experimenter. The instrumentation system was tested through a pilot investigation in which lingual vibrotactile and auditory scaling behavior was determined for a group of 20 normal speakers and a group of 10 stutterers. Results suggested that the instrumentation, utilizing the psychophysical scaling methods of magnitude estimation and cross-modality matching, may serve as a useful research tool for investigating the possible iterations of auditory and oral vibrotactile sensory processes.
Mapping musical intervals to affective qualities: A projective study
Authors: Makeig Scott
Published: October 2005

Many claim that the various musical intervals used in Western music create identifiable affective impressions which musicians use for musical communication. Alain Danielou has proposed, furthermore, that these affective impressions form a space with a three-dimensional structure isomorphic to the natural three-dimensional structure of the intervals themselves (ratios composed of positive and negative powers of 2, 3, and 5). To test this hypothesis, 36 Marathi-speaking college students at Ahmednagar College, Maharastra, India, were asked to imagine that each of 24 complex-tone melodic intervals was the “sound-name” of a person in some distant village. They were then given 36 bipolar adjective pairs and asked to rate the personality of the parson they imagined on five-point scales. (Previous studies have shown that subjects make affective judgments about sounds far more easily when imagining personalities than when rating the sounds themselves.) Results indicate that Indian students associate the main intervals used in Western music with separable personalities, and that these personalities compare well with those Western listeners reported in a previous study. [Work supported by the American Institute of Indian Studies.]
Acoustic scattering in an ocean environment: II. Shallow water applications
Authors: Sammelmann Gary S. , Hackman Roger H.
Published: October 2005

At a previous meeting of the Acoustical Society of America [R. H. Hackman and G. S. Sammelmann, J. Acoust. Soc. Am. Suppl. 1 78, S76(1985)] we presented a transition matrix formalism for the acoustic scattering in an inhomogeneous waveguide. Here, we report on an application of this formalism to the acoustic scattering from elastic targets in a range-independent shallow water environment. Particular emphasis is placed on identifying features in the backscattered wave which are unique to this environment and on elucidating the underlying physical mechanisms responsible for these features. [Work supported by the Office of Naval Research.]
Bistatic cross sections of thin spherical elastic shells at resonance, and the resonance order
Authors: Werby Michael F. , Überall Herbert
Published: October 2005

The acoustic scattering amplitude of elastic objects separates into specular-reflection terms, and elastic-resonance terms [L. Flax et al., J. Acoust. Soc. Am. 63, 723 (1978)]. For separable geometry, this holds for the individual mode amplitudes separately, and the problem arises how to classify the oberved resonances as to their mode order. For cylindrical scatterers at normal incidence, where the modal amplitudes contain cos nφ, the experimental solution is provided by observing the corresponding “daisy” pattern of the resonant bistatic cross section after isolating it by the MIIR method [G. Maze and J. Ripoche, J. Acoust. Soc. Am. 73, 41 (1983)]. We demonstrate here, for the case of spherical aluminum shells of thickness 0.1%, that mathematically, the order of a resonating mode is determined by coherent subtraction of the soft-sphere nonresonant background, and observation of the remaining bistatic resonant cross section whose pattern is determined by Pn, (cos θ). [H. Überall was supported by the Office of Naval Research.]
Synthesis of backscattering from an elastic sphere using the Sommerfield-Watson transformation and giving a Fabry-Perot analysis of resonances
Authors: Williams Kevin L. , Marston Philip L.
Published: October 2005

The Sommerfield-Watson transformation was recently applied to the acoustical backscattering from elastic spheres in water having ka > 1. Expressions for the scattering due to each class of elastic surface wave (e.g., the Rayleigh wave) were interpreted in terms of contributions from repented circumnavigations. In this presentation these expressions are summed in closed form as in the analysis of Fabry-Perot resonators. This closed form exhibits resonance behavior as is shown for the particular case of the Rayleigh wave on a tungsten carbide sphere. The sphere's form function is synthesized by adding the Fabry-Perot type contributions to the specular reflection. The procedure is confirmed by comparison with the exact backscattering form function magnitude |f| for an aluminum sphere is the range 10<ka<30 and a tungsten carbide sphere 10<ka<80. It is also shown that in the tungsten carbide case the interference of the specular and Rayleigh contributions produce the underlying structure in |f| while the whispering gallery wave resonances produce a finer superposed structure. Phase shifts are identified which affect the signature in |f| of the Rayleigh-wave resonances. [Work supported by ONR.]
Detecting spectral and temporal target differences in the harmonic complex
Authors: Daniel Jane E. , Kubovy Michael
Published: October 2005

We created pairs of harmonic complexes identical except for one harmonic (the target). Varying target amplitude and/or phase resulted in stimulus pairs which were different either in the frequency domain (spectral target difference) or in the time domain (temporal target difference). A signal detection analysis was applied to subjects' detection of spectral and temporal target differences at low through high harmonics. Spectral target differences were detectable at low harmonics only. Temporal target differences were detectable over a wider range of harmonics than previously claimed [H. Duifhuis, J. Acoust. Soc. Am. 48, 888–893 (1970)]. Using an adaptive psychophysical method we found that the number of low harmonics where spectral target differences were detectable varied with fundamental frequency. This result is not consistent with Duifhuis' (1970) observations, but does follow quantitative predictions based on the critical bandwidth, as well as other findings [R. Plomp, Aspects of Tone Sensation (Academic, London, 1976)].
Predicting the future from speech timing: Japanese data
Authors: Port Robert , Maki Daniel P.
Published: October 2005

Attempts were made to simulate aspects of the perceptual system by predicting when significant phonetic events are going to occur. The prototype model maintains a grammar of upcoming syllables and periodically computes (1) an instantaneous probability for each possible upcoming segment type using temporal information present at that point, and (2) a probability density function of the onset of prominent acoustic boundaries. Applied to some Japanese data [Port et al., J. Acoust. Soc. Am. (1982)] the model was trained on the speech of five speakers who read a controlled set of Japanese words (like baku, baaku, bakku). It trains by finding the best linear combination of segmental durations to predict (1) locations of future segmental boundaries, as well as (2) syllable-type possibilities (given the tiny implicit grammar of the experiment). The system was tested on five different speakers reading the same list and was able to anticipate word identity with fair accuracy. Although this system relies on the mora-timing constraint in order to work (since this regularity makes future events predictable), it does not directly employ the mora in its computation.
Consonant intelligibility in sentences: Effects of word position and narrow-band processing
Authors: Schmidt-Nielsen A.
Published: October 2005

The intelligibility of pairs of consonant sounds was investigated using pairs of interchangeable sentences, e.g.: He is studying (Job/Jove) in his world religion course. There were three pairs of sentences for each contrast, with the contrast occurring in word initial, word medial, and word final position. The test conditions included a 2400 bit/s linear predictive coding (LPC) voice processing algorithm and unprocessed speech. There were 60 listeners in each condition. The consonant pairs selected for this experiment were among those that had been shown to be most vulnerable under LPC processing in previous research [A. Schmidt-Nielsen, J. Acoust. Soc. Am. 74, 726–738 (1983)]. Individual pairs were more poorly recognized in some word positions than in others. Contrary to previous results, the average performance for phonemes in word medial and final positions was as good as for word initial position. These results will be compared with earlier results using VCV fragments excised from running speech and with results from standard intelligibility tests.