bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual differences in the perception of frequency changes in three-element sequences
Authors: Lauter Judith L.
Published: October 2005

Three-element sequences consisting of pure tones, complex tones, or combinations of the two were prepared for testing. Complex tones were designed in a variety of ways for testing frequency perception: For example, in an “embedded” design, components at 100-Hz separation ranged from 500–1500 Hz with the “figure” 1000-Hz component 12 dB above the other, “ground” components; frequency change affected only the 1000-Hz component. In a second design, components at 100-Hz separation began with 1000 Hz and ranged to 2000 Hz; amplitudes of all components were equal, and all changed to signal a frequency change. Performance on discrimination and identification tasks with such signals, comparing monaural and dichotic presentation, showed dramatic individual differences among a group of four observers. Some listeners could hear 3- to 6-Hz changes in pure tones, but performed at chance when listening to complex tones of the first design. Other listeners' performance was strikingly better for complex tones than for pure tones. Results can be used to provide support for hypotheses regarding the basis for individual differences in perceptual testing. [Work supported by AFOSR.]
Frequency-difference thresholds for tones in noise for the cat: Comparison with auditory nerve responses
Authors: Costalupes J. A.
Published: October 2005

Frequency-difference thresholds for 950-Hz tones in the presence of continuous broadband noise were obtained from three cats using a behavioral paradigm described previously [J. A. Costalupes, J. Acoust. Soc. Am. 74, 758–764 (1983)]. Four noise spectrum levels ranging from 13.5–43.5 dB SPL were used and the same signal-to-noise ratio was used at each noise level. The signal-to-noise ratio was approximately 9 dB above mean behavioral detection threshold for a 1-kHz tone in noise for each cat. The largest frequency-difference thresholds for each cat were noted at the lowest noise level. Frequency-difference thresholds were approximately constant at the higher noise levels. Results will be compared with the representation of tones in noise in the responses of populations of auditory nerve fibers in the cat, which reveal rate-change information over a similar range of stimulus intensities.
Evaluation of sonar phase-altered audio
Authors: Berlage E. J.
Published: October 2005

Some researchers have indicated that substantial improvements in the sonar audio detection threshold may be achieved by a technique referred to as phase-altered audio. The technique described in the literature, sometimes referred to as the masking level difference phenomenon, involves phase shifting the signal 180° and presenting this to one ear while the unphase shifted signal is presented to the other ear. The noise background is presented in phase at each ear. Alternatively, the noise to one ear may be phase shifted (180°) and the signal presented in phase at each ear. The degree of improvement is a function of the frequency of the signal and the degree of noise correlation. While it is clear from the literature that large improvements in audio detection threshold may be achieved under laboratory conditions where the signal and noise can be independently controlled, it is not clear how this phenomenon can be utilized to improve the audio presentation to sonar operators. A series of tests with a cylindrical array sonar was conducted at a US Navy Ashore Training Facility and a contractor test facility to determine if a phase-altered approach offers any substantial improvements to sonar operators on a passive sonar. The tests showed no significant benefit from the masking level difference phenomena for any phase-altered audio mode in the normal operating range of passive sonar half-beam noise correlation. But there was a significant improvement in sum (right half-beam plus left half-beam) beam audio performance for high negative half-beam noise correlation and with difference (right half-beam minus left half-beam) beam audio performance for high positive half-beam noise correlation. Any improvement in performance at high half-beam noise correlations was due primarily to the sum or difference beam gain and not the masking level difference phenomena. [Work supported by NAVSEA.]
Intonational upstep in Arabic
Authors: McCarthy John J.
Published: October 2005

An intonation contour used for echo questions and exclamations in Egyptian Arabic has been determined to be an instance of upstep, the systematic raising of the pitch level of all high and low tones at every accented syllable in an intonation phrase. This contour was investigated by constructing lists of two to five adjectives from the set sooda wbeeDa wHamra wxaDra wSafra, “black and white and red and green and yellow,” with 20 lists of each length constructed so that all words and pairs of adjacent words are equally frequent in all positions. These were then read by a native of Cairo under three different conditions of emphasis. Fundamental frequency values for accented syllables in the resulting utterances were averaged by position in the list. Results are compared to the model of downstep in Liberman and Pierrehumbert [“Intonational invariance under changes in pitch range and length,” in Language Sound Structure, edited by M. Aronoff and R. Oehrle (1984)]. [Work supported by NSF BNS-8121002 and System Development Foundation 626.]
Voice fundamental frequency changes associated with clinically identified stress state
Authors: Anderson Samuel W. , Dillon Donald
Published: October 2005

An upward shift in voice fundamental frequency (pitch) has been reported in human subjects undergoing a wide variety of experiences that are assumed to be stressful [J. K. Darby, Ed., Speech Evaluation in Psychiatry (1981)]. Precise measurement of pitch rise as a function of ongoing physiological stress level was obtained from 35 patients with panic disorders and 18 controls undergoing a biochemical challenge (infusion of sodium lactate) that is known reliably to elicit stress reactions from panic patients within 20 min, but not from normals. Pitch was computed from the narrow-band harmonic spectrum of the word “five” uttered during the course of a counting task performed at 5-min intervals during the infusion. Twenty-one patients who panicked showed an average pitch rise of about 1 semitone in the 5-min period before panic, and reached a maximum of 2 semitones which was significantly related to time of panic onset. Among 14 patients who did not panic, pitch showed no consistently upward trend, but did reach a maximum significantly above that of the controls. Among the controls, panic never occurred, and pitch change was negligible.
Generation of elastic ultrasonic waves by electric spark
Authors: Kishoni Doron , Sachse Wolfgang
Published: October 2005

The ultrasonic elastic waves generated while an electric spark strikes a solid are investigated. Attention is given to the interaction with aluminum specimens and to cases where no apparent damage is observed. Several mechanisms are suggested as the source for the generated waves, and experiments investigating each of these mechanisms are described. It is found that the thermo-elastic mechanism is of primary importance in the range of electric currents considered. As in the case of low energy laser-generated ultrasound, the ablation mechanism becomes significant only at higher currents, when visible damage to the surface of the specimen is apparent. [Work supported in part by Materials Science Center at Cornell University.]
The quasicrystalline approximation and multiple scattering of waves in random media
Authors: Varadan Vasundara V. , Varadan Vijay K.
Published: October 2005

The quasicrystalline approximation (QCA) was first introduced by Lax to break the infinite heirarchy of equations that results in studies of the coherent field in discrete random media. It simply states that the conditional average of a field with the position of one scatterer held fixed is equal to the conditional average with two scatterers held fixed, i.e., 〈ψ〉iji = 〈ψ〉ii. The QCA has met with great success for a range of concentrations from sparse to dense and for long and intermediate wavelengths. In this paper, the QCA is interpreted as a partial resummation of the multiple scattering series that includes only two body correlations and yields the same dispersion equation. Explicit improvements to the QCA are presented that still require only a knowledge of the two body correlation function.
Acoustic screening for vocal pathology
Authors: Laver John , Mackenzie Janet , Hiller Steven
Published: October 2005

A computer-based acoustic system for detecting signs of laryngeal pathology from the tape-recorded speech waveform (40 s of continuous speech) is described. The system uses a parallel processing technique for pitch detection, with phase compensation, low-pass filtering, nonlinear smoothing for intonational baseline measurement, and local perturbation analysis. This provides two types of data: intonational data derived from the smoothed fundamental frequency trend line and waveform perturbation, which reflects irregularity of vocal fold vibration. Acoustic results are presented for a control group (100 speakers) and compared with the results for 80 speakers with known laryngeal disorders. The value of these results in screening for the effect of laryngeal abnormalities is examined. Statistical treatment of the data allows over 80% of speakers with known pathology to be differentiated from the control group. A second stage of analysis examines the possibility of using acoustic profiles to discriminate between different classes of vocal fold pathology (e.g., carcinoma, nodules, and Reinke's oedema). The relative discriminatory power of individual and combined acoustic measures is discussed. [Work supported by British Medical Research Council.]
Effects of anisotropic poroelastic beds on wave propagation in shallow water
Authors: Yamamoto Tokuo , Badiey Mohsen
Published: October 2005

Wave propagation in seabeds is modeled by the propagator matrix derived from the Biot theory of anisotropic poroelastic media. The theoretical calculations are compared with measurements of wave-induced pore pressure distributions in sand beds in wave tanks as well as in the field. It was found that a strong coupling between the shear waves and the two compressional waves exists in anisotropic beds which is absent in isotropic beds. The intrinsic coupling in the anisotropic beds is responsible for strong wave attenuation and wave reflection. [Work sponsored by ONR, Code 425UA].
Attenuation changes due to diagenesis in marine sediments
Authors: Anderson Roger N. , Goldberg David S. , Moos Daniel
Published: October 2005

Cenozoic marine sediments were drilled and cored by the Deep Sea Drilling Project at Site 613 in the Baltimore Canyon Trough, and four-channel sonic waveforms were recorded from 115 to 585 m below sea floor. Compressional wave velocities and spectra were calculated from the sonic waveforms. In situ porosity was estimated and compared to core measurements. As expected, velocity increased with depth as porosity decreased. However, the energy loss between near and far receivers increased and the peak crosspower frequency decreased with depth, suggesting that attenuation increases over the same interval. The large changes in energy and frequency cannot be explained solely by changes in the elastic propeties of the sediments. We model the observed compressional wave spectra using measured values of velocity and density. Reasonable fits to the observed spectra are obtained using either a constant Q (CO) or nonconstant Q model. For the CO model, O decreases from 100 to 20 over this depth interval. Diagenesis observed in the recovered core increases with depth, and the number of low aspect ratio pores increases as the porosity decreases. The sonic attenuation can be explained by heat loss due to fluid flow in low aspect ratio pores.
Boundary layer induced pressure fluctuations on a compliant surface
Authors: Williams J. E. Ffowcs
Published: October 2005

Surface compliance admits the possibility of wave energy absorption from the flow. Absorbed also is the momentum flux difference between the incoming and reflected waves, the streamwise component of which represents a change in surface friction. The momentum flux in evanescent waves is similarly exchangeable with the surface, and in subsonic flows this part is usually, by far, the most significant. This paper discusses the fundamental aspects of modeling this problem through an acoustic analogy.
Flow noise in a hydrophone resting on the sea floor
Authors: Strasberg M.
Published: October 2005

When a hydrophone is resting on the bottom of the sea, low-frequency noise may be induced in the hydrophone by water flowing past it. Even though the flow may be negligible at the very bottom, pressure fluctuations generated in the turbulent boundary layer developed by natural currents flowing above the bottom will be transmitted to the hydrophone and result in noise. Estimates of the level of this locally generated low-frequency noise are presented, using dimensional analysis to extrapolate from data on boundary-layer pressure fluctuations obtained in wind tunnels and on the ground in the presence of natural winds. Disagreements between the two sets of data are discussed. The estimates are compared with previously reported levels of subsonic ambient noise measured in the sea with bottom-mounted hydrophones, to determine whether the measured levels were perturbed by the locally generated boundary-layer noise.
An experimental study of the effects of turbulence on the rise time of shock waves propagation in the atmosphere
Authors: Layton Bruce A. , Bass Henry E. , Bolen Lee N.
Published: October 2005

As a shock wave propagates through the atmosphere various effects change the waveform. Nonlinear steepening tends to shorten the rise time of the leading and trailing edges of the shock. Frequency dependent dissipation and scattering from atmospheric turbules tend to lengthen the rise time. Simultaneous measurements of turbulence (i.e., wind velocity and temperature fluctuations) and shock waveforms resulting from supersonic projectiles were obtained and analyzed. The shock wave measurements required dielectric capacitive microphones specifically designed for this application. The simultaneous measurement of turbulence parameters and shock waveforms are the first reported and allow for the comparison between measured rise times and those computed assuming turbulence is the dominant mechanism affecting the rise time. The measured rise times are also compared to those computed considering only relaxation effects (ignoring turbulence). The rise times computed from those two different mechanisms are similar in magnitude; both agree reasonably well with measurements. [Work supported by ARO.]
Propagation and attenuation of intense tones in air-filled porous materials
Authors: Nelson D. A. , Blackstock D. T.
Published: October 2005

In a previous presentation [J. Acoust. Soc. Am. Suppl. 1 74, S59 (1983)] it was demonstrated that the nonlinear mechanism for propagation in bulk porous material is an amplitude-dependent resistivity of the form r = r1 + r2u sgn(u), where u is the instantaneous particle velocity and r1 and r2 are constants that depend on porosity and material geometry. An approximate Helmholtz equation was derived that governs the change in signal harmonies with distance. Recently obtained numerical solutions of this equation compare favorably with experimental data. By assuming that harmonic interaction is weak, we have obtained analytical solutions for the amplitude and phase of the fundamental. It is found that the attenuation increases at high intensity, while at the same time the phase velocity decreases. Experiments have been done with Kevlar® 29 in the porosity range 0.94 to 0.98, in the frequency range 500–1500 Hz, at SPLs up to 165 dB. The experimental data confirm the predictions. [Work supported by NASA and ONR.]
Exact psychometric functions for a wideband envelope detector
Authors: McGill William J. , Teich Malvin C.
Published: October 2005

Recent calculations of exact psychometric functions traced by an envelope or energy detector operating in two-alternative forced choice to decide between signal and noise, disclose that the classical Gaussian approximation converges slowly to the exact distribution. Hence a commonly accepted estimator of degrees of freedom (E75/N0)2 may be quite poor when the degrees of freedom are fewer than 50. Jeffress used his electronic analog of envelope detection to show that human data are well-fitted by chi-distributions with degrees of freedom between 10 and 30. The present study confirms Jeffress' findings on degrees of freedom and attempts thereby to refine estimates of auditory bandwidth based upon detection experiments. Calculation of exact two-alternative forced choice psychometric functions for sine waves in wideband noise proves to be surprisingly simple. It is easily done on a handheld programmable calculator using an iteration scheme to sum a finite series.
Effect of envelope fluctuations in simultaneous masking
Authors: Buus Søren , Florentine Mary
Published: October 2005

The purpose of this experiment was to examine the effect of short-term energy fluctuations in a masker. Maskers were a pure tone at 1075 Hz and two-tone complexes with the high component at 1075 Hz and the low component at frequencies between 755 and 1060 Hz. For masker levels around 90 dB SPL, signals were pure tones at 3400, 4000, and 4800 Hz; for masker levels around 70 dB SPL, signals were at 1600, 1850, and 2150Hz. Results show that two-tone maskers with frequency separations of 15 and 50 Hz produce up to 30 dB less masking than a pure-tone masker set equal to the overall level and 20 dB less than a pure-tone masker set to the level of a single component. With frequency separations of 160 and 320 Hz, masking is slightly less than that of a pure-tone masker with the same overall level. These results are inconsistent with a simple frequency selective energy-detector model and indicate that the auditory system can take advantage of brief periods of low energy to enhance detection of a tone. [Work supported by NIH-NINCDS.]
The use of interaural temporal disparities in lateralization tasks employing narrow bands of noise and sinusoidally amplitude-modulated tones: Effects of spectral locus
Authors: Trahiotis Constantine , Bernstein Leslie R. , Nuetzel John , Schiano Jeffrey L.
Published: October 2005

We wished to assess the relative potency of interaural temporal disparities in the fine structure and in the envelope of stimuli having continuous spectra. In order to do so, we employed an acoustic pointing task in which listeners varied the interaural intensitive difference of a 500-Hz narrow-band noise (the pointer) so that it matched the intracranial position of a second, experimenter-controlled, stimulus (the target). Targets were narrow bands of noise centered at octave intervals between 500 and 4 kHz. The bandwidths of the noises ranged from 50 to 400 Hz. These data will be compared to those obtained previously utilizing sinusoidally amplitude-modulated tones as targets. Both sets of data will be discussed in terms of modern theories of binaural hearing which presume that interaural temporal disparities within the envelope of high-frequency stimuli are processed similarly to interaural temporal disparities within the fine structure of low-frequency stimuli.
Quantitative determination of porosity: Theory and experiment
Authors: Lewis Kent , Wang Shaio-Wen , Adler Laszlo , Rose James H.
Published: October 2005

When an ultrasonic wave propagates in a solid with a low concentration of voids the attenuation coefficient is proportional to the scattering cross section of each void multiplied by the number of voids [Gubernatis and Domany, Rev. Prog. QNDE 2A, 833 (1983)]. Exact calculation was carried out for the scattering cross section of elastic waves as a function of ka from spherical voids in several solids. A turning point between low and high ka values of the scattering cross section provides a turning point at ka = 1. This turning point depends only on the ratio of transverse to longitudinal velocity in the solids—can be used to calculate both the pore radius and their concentration. Experimental method was developed to measure attenuation coefficient as function of frequency using ultrasonic spectroscopy system. The theoretical model was successfully tested experimentally for several aluminum cast materials containing porosity up to 6% and with average radius for 10–150μ. [This work was supported by the Center of NDE operated by Ames Laboratory for the Air Force Wright Aeronautical Materials Laboratory.]
Application of elastic guided waves for interface properties characterization
Authors: Rokhlin S. I.
Published: October 2005

We discuss a new ultrasonic method for evaluation of interface properties. The method is based on utilization of the ultrasonic interface waves, for bonded semispaces and of Lamb waves for bonded layers. Using theoretical analysis we select experimental conditions in a manner such that the interface wave induces only shear stresses on the interface. This makes it possible to estimate the effective shear modulus of the interface. The effect of boundary conditions between layers on Lamb wave propagation and conversion is also considered. The transformation coefficients for Lamb waves conversion on the bonded and nonbonded regions between layers are derived and discussed.
Augmentation of acoustic transmission by a transition layer
Authors: Pierucci Mauro
Published: October 2005

It has already been reported by the author at a previous meeting [J. Acoust. Soc. Am. Suppl. 73, S95 (1982)] that certain types of transition layers can improve the transmission of acoustic waves from one medium to another. In this paper, conditions under which the transmissions of an acoustic wave is enhanced by the transition layer are presented. The case of a finite thickness elastic layer has been studied and it has been determined that at certain key frequencies, an optimum transition layer thickness exists which greatly improves the interaction between the two media.
Diffraction by acoustically penetrable scatterers
Authors: Copeland James E. , Milner O. Martin
Published: October 2005

The problem of acoustic diffraction by nonrigid scatterers in water was treated both theoretically and experimentally. A theoretical model of diffraction by a matrix of square or rectangular blocks was developed. The Helmholtz integral equation was solved by making Kirchhoff-type approximations that relate surface pressure to transmission and reflection coefficients calculated from the Brekhovskikh layered media model. Experimental measurements of pressure amplitude and phase difference were made on the shadow side of matrices of metal blocks. The blocks were insonified by sound waves of frequencies 2500 and 3500 Hz. An array of three hydrophones on the shadow side of a matrix sensed diffracted pressure amplitude and phase as a function of distance between the matrix and the hydrophones. Comparison of model predictions and experimental data shows good agreement. The agreement for small hydrophone-matrix separations becomes better with increasing ka where 2a is the outside dimension of the matrix. [Work supported by NAVSEA, Code 55N and DTNSRDC Code 1933.]
A temporal model of pitch perception based on spiral periodicity detection
Authors: Patterson Roy D.
Published: October 2005

The logarithmic spiral (base 2) offers a simple passive means of detecting the regularity observed in the streams of nerve pulses produced when phase locked fibers respond to periodic sounds. That is, if time is wrapped into a spiral with time zero at the spiral's origin, then when nerve pulses-flow outwards along the path of the spiral, the pulses of a regular stream will coalesce onto spokes emanating from the center of the spiral once per cycle. The spoke pattern has a fixed shape and it rotates around the spiral as the periodicity of the pulse stream varies. Secondary units can be used to detect coalescence on spoke patterns with specific orientations and so convert the temporal pitch information into spatial pitch information. The spoke pattern completes one revolution as the pulse rate rises or falls an octave, and the primary intervals of the Just diatonic scale produce the simplest combined spoke patterns. Thus, the logarithmic spiral provides a basis for a temporal model of pitch perception which can also predict musical harmony.
Seismic sense and seismic signals of a frog
Authors: Lewis Edwin R. , Narins Peter M. , Moore Steven W. , Lopez Pamela T.
Published: October 2005

Intracellular recording followed by tracing with intracellular dye has revealed that afferent saccular axons of the bullfrog (Rana catesbeiana) are acutely responsive to substrate-borne vibrations, with linear gain up to 3000 spike/s (neural response) per cm/s2 (seismic amplitude). Eighth-nerve (presumedly saccular) axons from the white-lipped frog (Leptodactylus albilabris) show even greater seismic sensitivity, with linear gain up to 20 000 spikes/s per cm/s2(up to 70 spike/s per Angstrom of vibrational displacement). In both species, the sensitivity frequency range matches well the principal spectra (approximately 10–300 Hz) of slow seismic waves (Rayleigh and Love waves) in moist soil. In synchrony with its airborne call (a 40-ms chirp), the male white-lipped frog often produces a seismic thump—with strong Rayleigh-wave and Love-wave components (peak accelerations ∼2 cm/s2 at a distance of 1 m from the frog) in the moist soil from which it calls. The thump waveforms match those produced by impulselike impacts on the soil surface, with spectra matching the frog's seismic sensitivity. Even in the absence of chirps, thumps provide male-male interaction responses in male white-lipped frogs. [Work supported by NSF (ERL) and NIH (PMN).]
Effects of speech rate upon the noise-induced illusory continuity of interrupted discourse
Authors: Bashford James A. , Meyers Mark D. , Brubaker Brad S. , Warren Richard M.
Published: October 2005

Bashford and Warren [Speech Communication Papers, Acoust. Soc. Am. (1979), pp. 423–426] reported that the noise-induced illusory continuity of interrupted speech is greater for normal discourse than for contextually degraded speech. When normal discourse was periodically interrupted by a louder, spectrally matched noise, the maximum interruption period permitting illusory continuity approximated the average work duration in the passage. The present study replicated that finding with a different discourse passage produced by a different speaker and played back at different rates. When the passage was played at its original speed, the limit of illusory continuity averaged 279 ms, or 95% of the average word duration. When playback rate was decreased 15%, the continuity limit increased 12.3% and equaled 93% of the average word duration. A 15% increase in playback rate produced a 17.7% decrease in continuity, with periodic interruptions equal to 92% of the average word duration. These results appear to be related to nonlinguistic temporal induction of signals by nosie, and to the effects of contextual information upon the perceptual organization of speech. [Work supported by NSF and NIH.]
Comparisons of spectrographic and computer-based measurements of speech timing characteristics
Authors: Smith Bruce L. , Hillenbrand James , Ingrisano Dennis R.
Published: October 2005

Historically, broadband spectrograms have been the primary method used for making temporal measures of speech. More recently, computer graphics terminals have been used to produce digital oscillograms. However, results that have been obtained using spectrographic and oscillographic measures have not always been in complete agreement. Although there are many factors that might account for such discrepancies, it is possible that the instrumentation differences have affected the results of these studies. The purpose of the present study was to compare temporal measurements from spectrograms with those obtained from computer oscillograms. Fifty productions by three subjects (one adult male, one adult female, and one child) were measured using (1) wideband spectrograms and (2) oscillograms displayed on a high-resolution graphics terminal. Results from the two measurement procedures typically differed by 5–10 ms for a number of different temporal properties. Although the findings suggest that employing different instrumentation techniques may have only minimal effect on durational measures, the observed effects tended to be quite systematic. Given that investigators typically assess their measurement reliability to be on the order of about 5 ms, however, it would appear that measurement differences which might occur due to analog versus digital instrumentation are negligible.
Spanish: A free rhythmical language
Authors: Toledo Guillermo A.
Published: October 2005

The purpose of this paper is to compare the rhythmic patterns of several speech materials by applying several styles of reading: poetry in free verse in “citation” style read by its author (Cuban speaker, 357 feet), prose in “citation” style read by the novelist (Colombian speaker, 711 feet), an essay read by the author in “normal” style (Argentinian speaker, 295 feet), and spontaneous speech both in “normal” and “casual” style (Argentinian speaker, 496 feet). The material was digitized and the feet segmented and measured. In the data on poetry, the statistical treatment showed a tendency toward isochrony mostly in feet of short size while the reverse was true in feet of long size. However there was a degree of proportional increase in the foot duration with respect to the increase of the foot size in the rest of the material, mainly in feet of high frequency, i.e., the short ones. Spanish would therefore appear to be a free rhythmical language rather than a syllable or a stress-timed language.
Some observations on segment duration and its interaction with the fundamental frequency contour in Swedish
Authors: Lyberg Bertil
Published: October 2005

In a previous study [B. Lyberg, J. Phonet. 9, 97–103 (1981)] quite strong evidence was found in favor of a relationship between segment duration and fundamental frequency change in certain positions of an utterance such as the phrase final position. The speech material used in the study was built up of Swedish words containing only phonologically long vowel segments. In the present investigation this relationship was studied once more but this time for both phonologically long and short vowel segments in order to elucidate the interaction between the signaling of the quantity distinction and the fundamental frequency contour. The results show that the segment duration of the stressed vowel in monosyllabic words in phrase final position is positively correlated with the fundamental frequency change of the terminal fall when the vowel is followed by a voiced consonant for both phonologically short and long vowels. When the vowel is followed by a voiceless consonant the terminal fall seems to be compressed in the time dimension.
Pause structure in synthetic speech
Authors: Klavens Judith L. , Edelstein Maria X. , Basson Sara
Published: October 2005

Intonation contouring of synthetic speech improves both intelligibility and comprehension [Slowiaczek and Nusbaum, to appear], while flattening appears to interfere with speech perception [Larkey and Danley (1983)]. Given the proven importance of F0, several problems remain in defining the domain of prosodic contour. Among the issues are pauses and intonational domains. These are particularly critical in an unlimited text-to-speech system where input is often unpunctuated long complex sentences. This paper reports on current work to determine pause structure of synthetic speech as a component of specifying the domain of prosodic contouring. The system uses a deterministic bottom-up parser to give a syntactic analysis of a sentence. Based on this and other information, a pause structure is computed algorithmically. The pause-parsed structure then serves as input for later stages in the application of F0. Syntactically based pause insertion is compared with a simple function/content word-based pause-insertion algorithm. We give evidence that the insertion of pauses based on a syntactic parse increases naturalness.
Long-range transient sounds recorded in the Arctic
Authors: Northrop John
Published: October 2005

Several types of low-frequency transient signals were observed on hydrophones suspended from the ice in the Arctic Ocean during April 1984. One type, containing both bubble pulse harmonics and strong frequency dispersion, is believed due to distant underwater explosions. In one case, a range of 900 ± 90 km is calculated using the time-frequency dispersion method [T. C. Yang, J. Acoust. Soc. Am. 76, 262–273 (1984)]. For this event, a charge size of 5-lb TNT detonated at 150 ft is estimated from the bubble pulse interval, S/N ratio, and propagation loss. Another type of transient, lasting for several minutes, contains several distinct phases resembling the arrivals of P, S, and T waves from undersea earthquakes. Calculations of the T-phase minus P-phase arrival time difference give a range of 360 km, which is approximately the distance of the array from the Nansen ridge where T phases have been reported previously [R. E. Keenan and I. Dyer, J. Acoust. Soc. Am. 76, 819–825 (1984)]. The T phase on our records, however, does not have a sharp onset, energy arriving more or less continuously after the P arrival. Coupling of the crustal PN and SN phases with the sound channel is suggested for excitation of the T phase. [Work supported by NOSC IR/IED.]
Numerical modeling of ice-interacting acoustic signals in the Arctic using a new Fast Field Program
Authors: Lawrence T. , Tango G.
Published: October 2005

Propagation of acoustic waves in an ocean waveguide bounded above by plane ice layers can be readily modeled using the “Fast Field Program” (FFP), as developed by DiNapoli (1968), Kutschale (1971), and Schmidt (1982). The “direct global matrix” FFP formulation embodied in the “SAFARI” algorithm of Schmidt [H. Schmidt and F. Jensen, J. Acoust. Soc. Am. Suppl. 1 76, S10 (1984)], permits rapid computation of transmission loss from a cw point source as a function of receiver range for multiple source/receiver depths, as well as synthetic pulse and seismogram generation. In this preliminary study, a basic model for short to intermediate range under-ice propagation is developed, using isovelocity and depth-dependent ice layers, and extremal values for, e.g., shear velocity and attenuation. Using this model, results of FFP computations are given for a series of frequencies (15 to 1500 Hz) and source/receiver depths. For a given experimental configuration, various shear velocity and attenuation models were investigated to show the effects on net TL due to compressional and shear wave refraction and conversion in the ice.
Spatial distribution of discrete noise sources under Arctic Sea ice
Authors: Holliday D. V. , Cummings W. C.
Published: October 2005

Numerous temporally and spatially discrete noise sources were localized under landfast Arctic ice in Kotzebue Sound, Alaska, during the spring of 1984. The localization was accomplished by determining bearings of the sounds from relative times of arrival at hydrophones positioned at the corners of a triangle of known dimensions. Transient ice generated noises, vocalizations of the ringed seal (Phoca hispida), and sounds associated with maintenance of ringed seal breathing holes or lairs were found to be associated largely with the ice topography as measured from the surface, e.g., refrozen cracks and pressure ridges. Selected spectra and levels are also presented. [Work supported by OCSEAP.]
An analytical model for waveguide acoustic probe systems
Authors: Mahan J. R. , Howard R. E.
Published: October 2005

In situations where unsteady pressures must be measured in hot environments, thermal isolation of the pressure transducer is often afforded by an acoustic waveguide. The transducer is mounted in a side branch a relatively short but thermally safe distance from the hot open end of the waveguide. The other end of the waveguide, a relatively large distance beyond the transducer, is sealed. An inert gas is bled into the waveguide at the sealed end to keep it clear of contaminants and to provide additional cooling beyond that offered by natural convection. In theory, plane waves. propagating down the waveguide and past the transducer are sufficiently attenuated upon their return, after reflection from the sealed end, that very little distortion occurs at the transducer. In practice, there is always some distortion of the signal at the transducer produced by the finite length of the waveguide, the impedance mismatch introduced by the transducer installation, and the temperature gradient along the length of the waveguide. A detailed analytical model of such a probe system has been developed which incorporates all of the essential features. Results of a parametric study using this model are presented which establish the sensitivity of the probe pressure transfer function to the system design and operating characteristics.
Detection and sizing of thermal cracks in railroad wheels
Authors: Fahmy Mahmoud N. , Finch Robert D.
Published: October 2005

An impact on the rim of a railroad wheel causes a wave which travels around the rim at a constant speed. The reflection of this rim wave from a thermal crack can be isolated from other traveling wavelets by using a complex cepstrum analysis. The power cepstrum has already been used to detect the presence of a hand-made surface crack in a wheel rim [M. N. Fahmy and R. D. Finch, J. Acoust. Soc. Am. 75, 1283–1290 (1984)]. Signals from three wheels with different crack sizes and types were analyzed and the ratio between the maximum amplitude of the reflection echo to the maximum amplitude of the incident wavelet (AR) was measured. The AR values measured experimentally were compared with values obtained theoretically. Field data were collected from a test consist train having wheels with different known defective conditions. Both power and complex cepstrum analysis were used in the analysis of the field data and the detection rate was 91% and the false alarm rate was 28%. In the cepstrum analysis, the aliasing error was measured and the minimum phase condition was used with the complex cepstrum analysis.
Evaluated Rayleigh integrals for delta-function driven circular membranes
Authors: Warshaw Stephen I.
Published: October 2005

Analytic and semianalytic evaluations of the pressure field due to impulsively driven flat membranes imbedded in an infinite plane baffle by using Rayleigh's integral are discussed and presented for a variety of delta function type motion distributions across the membrane. We first review the field due to a circular membrane subject to a uniform delta function acceleration, and then treat more complex membrane motions composed of different spatially and temporally dependent delta function accelerations. These will include annular (ring) and uniformly expanding annular (moving ring) distributions. In some cases closed analytic forms for the pressure field can be obtained, while in others elliptic integrals result, which can be conveniently calculated by Gauss-Chebyshev quadrature of the first kind. All evaluations are performed directly in the time domain. [Work performed under auspices of U.S. Department of Energy by LLNL under Contract W-7405-Eng-48.]
Radiation impedance for baffled rectangular pistons of arbitrary aspect ratio at any frequency
Authors: Miller G. Kirby
Published: October 2005

An algorithm has been developed for calculating the complex farfield radiation impedance of a plane rectangular piston vibrating at any frequency in a coplanar infinite baffle for any ratio of length to width. The method is based on previously published expressions for the radiation from an infinite strip [J. W. Miles, J. Acoust. Soc. Am. 20, 652–1664 (1948)] and for the radiation from a long strip [O. A. Lindemann, J. Acoust. Soc. Am. 52, 1045–1048 (1972)], as well as on the expressions and calculated values found in the thesis [D. S. Burnett, “Radiation Impedance Functions of Rectangular Pistons and Their Application to Sound Transmission Through Finite Depth Apertures,” Ph.D. dissertation, University of California, Berkeley, CA (1969)]. Six different power and asymptotic series (some believed new) in combination with three empirically derived algebraic expressions are shown to be valid for each of four contiguous regions in the dimensionless length and width parameters, kl and kw. The boundaries of the regions are slightly different for the real and the imaginary parts. The algorithms are amenable to very fast computer calculation and produce results that are usually accurate to within a few percent.
One-dimensional acceleration waves in a compressible fluid mixture
Authors: Batra G. , Bedford A.
Published: October 2005

The method of singular surfaces is used to study the propagation of one-dimensional acceleration waves in compressible fluid mixtures of the type described by Bedford and Drumheller [Arch. Ration. Mech. Anal. 68, 37–51 (1978)]. It is found that four wave speeds are possible for a mixture of two constituents. The temporal evolution of the amplitude of the wave is governed by a first-order ordinary differential equation—the Bernoulli equation. Thus, depending on the initial amplitude, constitutive assumptions and the state of the material ahead of the wave front, the wave may grow or decay. The possibility of shock formation in finite time is not ruled out. These results are obtained without any specific representation for constitutive relations and hence are common to materials within a consecutive class and may contribute in the evaluation of constitutive functions for such mixtures through experimental study of wave behavior. As an extension to this work, preliminary results on the propagation of acceleration waves in bubbly liquids are obtained.
“Intensity attention bands” in normal and impaired listeners
Authors: Perkins Mark E. , Wightman Frederic L.
Published: October 2005

In a recruiting ear the perceived intensity (i.e., “loudness”) of a sound slightly above threshold increases more rapidly with sound intensity than normal. If “loudness” mediates “Intensity Attention Bands” (IABs) [e.g., Luce et al., Percept. Psychophys., 49–54 (1976)], then IABs for intensity regions near threshold should be narrower in a recruiting ear than in a normal ear. The same range of “loudness” is produced by a narrower range of intensity in the recruiting ear. We used a variant of the roving-level discrimination paradigm to test the ability of listeners with normal hearing and with moderate hearing loss to discriminate changes in the intensity of a 1-kHz tone burst. As the difference (in dB) is increased between the level of a fixed priming stimulus and the level of the tones to be discriminated, performance deteriorates. Comparisons among the groups of subjects will be discussed.
Individual differences in auditory evoked responses: Comparisons of between-subject and within-subject variability in brainstem and cortical waveforms
Authors: Lauter Judith L. , Loomis Robert
Published: October 2005

Auditory evoked responses have been used for some time for diagnostic puposes. However, data regarding the range of normal variability have not been reported until recently. Published results have described variability across laboratories, across sessions within the same laboratory, and across subjects. However, although within-subject variability is also of obvious importance for interpreting clinical findings, this source of evoked-response variability has not been studied. An experiment was designed to study the normal between-subject and within-subject variability of AER amplitude and latency, comparing monaural versus binaural presentation, in several waveform peaks from brainstem to cortex. Results on monaural/binaural distinctions and other details of the responses show good agreement with earlier reports. In addition, observations on individual differences suggest that levels of auditory nervous system organization may be reflected in patterns of AER variability. [Work supported by NINCDS.]
Evoked response recovery functions using a “forward masking” paradigm
Authors: Arehole Shalini , Salvi Richard J. , Saunders Samuel S. , Hamernik Roger P.
Published: October 2005

The amplitude of the evoked response was measured in a “forward masking” paradigm. Normal hearing chinchillas with electrodes implanted in the vicinity of inferior colliculus were used as subjects. A probe of 10-ms duration was set at 10 dB above the evoked response threshold. The amplitude of the probe response was measured either in isolation or following a 100-ms adaptor. The level of the adaptor required to reduce the amplitude of the probe response by 50% was measured over a range of adaptor-probe interval in order to map out the recovery function. The adaptor and probe tone were at the same frequency and the recovery functions were measured at 500, 2000, 4000, and 8000 Hz. At short adaptor-probe intervals, relatively low level adaptors were sufficient to reduce the probe response by 50%; however, as the interval between probe and adaptor increased, the level of the adaptor required to reduce the probe response by 50% increased significantly. The results of the present study will be discussed in relation to earlier physiological and psychophysical results. [Supported by NIH 1ROI-NS1676 and NIOSH I-ROI-OH00364.]
On the use of masking to simulate the effects of sensorineural hearing loss on speech recognition
Authors: Humes Larry , Dirks Donald D. , Bell Theodore S. , Kincaid Gail E.
Published: October 2005

In the present experiment, broadband noise, shaped to match the hearing loss of four listeners with moderate sensorineural hearing loss with selected configurations, was presented to 12 normal-hearing subjects (four groups of three listeners each, one group for each impaired listener). Pure-tone thresholds for all subjects were measured from 125–8000 Hz at 1/3-oct intervals. The spectrum of the broadband noise presented to the normal hearers was adjusted so that masked pure-tone threshold was typically within 5 dB of that measured in the impaired listeners. A nonsense-syllable recognition test was then presented to all listeners, the levels being selected so as to cover the linear portion of the performance-intensity functions for the impaired listeners. The same sound pressure levels were then used for presentation to the normal listeners who listened to the nonsense syllables in the background of shaped noise. Comparisons are made between the performance-intensity functions and the consonant-confusion patterns for the actual and simulated hearing loss. In addition, the accuracy of the articulation index for predicting the performance of both groups of subjects (actual and simulated hearing loss) is evaluated. [Work supported by NINCDS.]
Prediction of speech intelligibility for normal-hearing and cochlear-impaired listeners
Authors: Ludvigsen Carl
Published: October 2005

First, frequency resolution and temporal resolution were compared with hearing thresholds and acoustic reflex thresholds for four normal-hearing and thirteen cochlear-impaired subjects. Two models, one for frequency resolution (model I), and one for temporal resolution (model II) provided a means of predicting individual frequency and temporal resolution from hearing thresholds for both normal-hearing and hearing-impaired listeners. Model I is based on the assumption that upward spread of masking increases in cochlear-impaired hearing with an amount proportional to the hearing threshold in dB HL. Model II is based on the assumption that the poststimulatory masked thresholds return to the level of the hearing threshold within a duration of 200 ms, independent of the level of the masker and the amount of cochlear hearing loss. Second, the word recognition ability of the same listeners was evaluated. Articulation index theory was applied to predict the results. It is concluded that speech intelligibility of cochlearly hearing-impaired listeners may also, to a first approximation, be predicted from articulation index theory.