bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental studies of attenuation in sediments
Authors: Stoll Robert D.
Published: October 2005

Recent theoretical work suggests that attenuation of acoustic waves in ocean sediments depends on two distinct types of energy loss; these losses result from inelasticity of the skeletal frame and motion of the pore water relative to the frame. In this paper, experimental evidence is presented which verifies the type of response predicted by the theoretical model. Torsional resonance and logarithmic decrement are measured over a wide frequency range in both water-saturated and dry sediments. A changeover from dominance by one type of loss to the other is clearly demonstrated by a change of response that is observed as the frequency is varied. Specially designed equipment is used which allows the intergranular stress to be controlled to simulate various depths of embedment in the sea floor. Both the theory and the experiments suggest that for some sediments the attenuation will vary in a manner quite different from the usual dependency on the first power of frequency that is often assumed.
Parametric acoustic sources of transient signals
Authors: Moffett Mark B. , Mello Peter
Published: October 2005

A theoretical treatment is formulated for transient, or broadband, parametric acoustic sources, i.e., parametric sources using an arbitrarily modulated primary carrier signal. This treatment makes use of previously calculated characteristics for steady-state, or narrow-band, parametric sources. The theory does not include saturation effects. A fortran computer program, using Fast Fourier Transforms, generates spectra and waveforms for specified modulation envelopes. Experimental results, in good agreement with the theory, are presented for a 30-μs pulse applied to a 4-mm active diameter, 2-MHz quartz-crystal underwater projector.
Nonlinear propagation of an asymmetric double exponential waveform
Authors: Rogers Peter H. , Weiner Andrew M.
Published: October 2005

A weak-shock solution is obtained for the nonlinear propagation of a waveform that initially has the form of an asymmetric double exponential. Such a wave shocks at its peak, so that shock growth and wave-amplitude attenuation occur simultaneously. Simple formulas for wave amplitude, shock amplitude, and arrival time are given as is an expression for the waveform. We also present a general technique for obtaining weak-shock solutions for the amplitude of any integrable waveform that forms a single shock.
Studies of place and manner of articulation in syllable-final position
Authors: Miller Joanne L. , Eimas Peter D. , Zatorre Robert J.
Published: October 2005

In three experiments we extended our earlier investigations of place and manner of articulation in syllable-initial position by examining the processing of information for these two features in syllable-final position. In all cases, the results indicated that the two features are processed in much the same way in the two syllable positions.
Author’s reply to ’’Comment on ’Weak shock solution for underwater explosive shock waves’ ’’ [J. Acoust. Soc. Am. 66, 308 (1979)]
Authors: Rogers Peter H.
Published: October 2005

It is noted that there are a number of equally valid methods that may be used to formulate weak shock theory.
Acoustic invariance in speech production: Evidence from measurements of the spectral characteristics of stop consonants
Authors: Blumstein Sheila E. , Stevens Kenneth N.
Published: October 2005

On the basis of theoretical considerations and the results of experiments with synthetic consonant-vowel syllables, it has been hypothesized that the short-time spectrum sampled at the onset of a stop consonant should exhibit gross properties that uniquely specify the consonantal place of articulation independent of the following vowel. The aim of this paper is to test this hypothesis by measuring the spectrum sampled at the onsets and offsets of a large number of consonant–vowel (CV) and vowel–consonant (VC) syllables containing both voiced and voiceless stops produced by several speakers. Templates were devised in an attempt to capture three classes of spectral shapes: diffuse-rising, diffuse-falling, and compact, corresponding to alveolar, labial, and velar consonants, respectively. Spectra were derived from the utterances by sampling at the consonantal release of CV syllables and at the implosion and burst release of VC syllables, and these spectra (smoothed by a linear prediction algorithm) were matched against the templates. It was found that about 85% of the spectra at initial consonant release and at final burst release were correctly classified by the templates, although there was some variability across vowel contexts. The spectra sampled at the implosion were not consistently classified. A preliminary examination of spectra sampled at the release of nasal consonants in CV syllables showed a somewhat lower accuracy of classification by the same templates. Overall, the results support an hypothesis that, in natural speech, the acoustic characteristics of stop consonants, specified in terms of the gross spectral shape sampled at the discontinuity in the acoustic signal, show invariant properties independent of the adjacent vowel or of the voicing characteristics of the consonant. The implication is that the auditory system is endowed with detectors that are sensitive to these kinds of gross spectral shapes, and that the existence of these detectors helps the infant to organize the sounds of speech into their natural classes.
Bimodal cues for speech loudness
Authors: Glave R. D. , Rietveld A. C. M.
Published: October 2005

This paper presents a bimodal (audio–visual) study of speech loudness. The same acoustic stimuli (three sustained vowels of the articulatory qualities ’’effort’’ and ’’noneffort’’) are first presented in isolation, and then simultaneously together with an appropriate optical stimulus (the speaker’s face on a video screen, synchronously producing the vowels). By the method of paired comparisons (law of comparative judgment) subjective loudness differences could be represented by different intervals between scale values. By this method previous results of effort-dependent speech loudness could be verified. In the bimodal study the optical cues have a measurable effect, but the acoustic cues are still dominant. Visual cues act most effectively if they are presented naturally, i.e., if acoustic and optical effort cues vary in the same direction. The experiments provide some evidence that speech loudness can be influenced by other than acoustic variables.
Effects of selected vocal disguises upon speaker identification by listening
Authors: Reich Alan R. , Duke James E.
Published: October 2005

This research was designed to investigate the effects of selected vocal disguises upon speaker identification by listening. The experiment consisted of 360 pair discriminations presented in a fixed-sequence mode. The listeners were asked to decide whether two sentences were uttered by the same or different speakers and to rate their degree of confidence in each decision. The speakers produced two sentence sets utilizing their normal speaking mode and five selected disguises. One member of each stimulus pair in the listening task was always an undisguised speech sample; the other member was either disguised or undisguised. Two listener groups were trained for the task: a naive group of 24 undergraduate students, and a sophisticated group of three doctoral students and three professors of Speech and Hearing Sciences. Both groups of listeners were able to discriminate speakers with a moderately high degree of accuracy (92% correct) when both members of the stimulus pair were undisguised. The inclusion of a disguised speech sample in the stimulus pair significantly interfered with listener performance (59%–81% correct depending upon the particular disguise). These results present a similar pattern to this authors’ previous results utilizing spectrographic speaker-identification tasks (Reich et al., 1976).
Encoding voice fundamental frequency into vibrotactile frequency
Authors: Rothenberg Martin , Molitor Richard D.
Published: October 2005

Measured in this study was the ability of eight hearing and five deaf subjects to identify the stress pattern in a short sentence from the variation in voice fundamental frequency (F0), when presented aurally (for hearing subjects) and when transformed into vibrotactile pulse frequency. Various transformations from F0 to pulse frequency were tested in an attempt to determine an optimum transformation, the amount of F0 information that could be transmitted, and what the limitations in the tactile channel might be. The results indicated that a one- or two-octave reduction of F0 vibrotactile frequency (transmitting every second or third glottal pulse) might result in a significant ability to discriminate the intonation patterns associated with moderate-to-strong patterns of sentence stress in English. However, accurate reception of the details of the intonation pattern may require a slower than normal pronounciation because of an apparent temporal indeterminacy of about 200 ms in the perception of variations in vibrotactile frequency. A performance deficit noted for the two prelingually, profoundly deaf subjects with marginally discriminable encodings offers some support for our previous hypothesis that there is a natural association between auditory pitch and perceived vibrotactile frequency.
Acoustic study of medial /t,d/ in American English
Authors: Zue Victor W. , Laferriere Martha
Published: October 2005

This paper describes the acoustic characteristics of medial /t,d/ in American English as a function of phonetic environment. The data consisted of some 3000 word tokens, each embedded in a carrier phrase, recorded on two separate occasions by six subjects, three male and three female. Quantitative results were obtained on the acoustic characteristics of each stop for all phonetic environments, as well as the difference between /t/ and /d/ for a given phonetic environment. The interaction between certain phonological rules such as flapping and glottalization and low-level phonetic recoding rules such as vowel nasalization and nasal deletion was investigated. Based on the statistics derived from our corpus, probabilities of occurrence were derived for all phonetic realizations. In addition, interspeaker variability was examined and a significant difference was found in the application of phonetic rules between male and female speakers.
Perception of the simple difference tone (f2−f1)
Authors: Humes Larry E.
Published: October 2005

The present study examined the dependence of difference tone level [L (f2−f1)] on the following parameters of the two-tone input: f1, f2/f1 (f2≳f1), L1, L2, and L1=L2. Difference tone levels were estimated in four normal hearers using a 2AFC adaptive temporal gap-masking paradigm. The key finding in this study is the apparent interaction of each factor with the other. For example, primary level (L1=L2) was found to affect the dependence of L (f2−f1) on f1 and on f2/f1. In addition, the frequency separation of the primaries (f2/f1) was also seen to exert an influence on the dependence of difference tone level on L1, L2, and L1=L2.
V
p
/V
s and Poisson’s ratios in marine sediments and rocks
Authors: Hamilton Edwin L.
Published: October 2005

The ratio of compressional wave velocity Vp to shear wave velocity Vs, and Poisson’s ratio in marine sediments and rocks are important in modeling the sea floor for underwater acoustics, geophysics, and foundation engineering. Vp and Vs versus depth information was linked at common depths in terrigenous sediments (to 1000 m) and in sands (to 20 m) to yield data on Vp vs Vs, and Vp/Vs and Poisson’s ratios versus depth. Soft, terrigenous sediments usually grade with depth into mudstones and shales; Vp/Vs ratios vary from about 13 or more at the sea floor to about 2.6 at 1000 m. Poisson’s ratios vary from above 0.49 at the sea floor to about 0.41 at 1000 m. In sands, Vp, Vs, and Vp/Vs have very high gradients in the first few meters; below about 5 m, Vp/Vs ratios decrease from about 9 to about 6 at 20 m; Poisson’s ratios vary from above 0.49 at the surface to above 0.48 at 20 m. The mean value of Vp/Vs in 30 laboratory samples of chalk and limestone is 1.90 (standard error: 0.03); mean Poisson’s ratio is 0.31. Literature data on basalts from the sea floor are reviewed. Equations relating Vp to Vs are given for terrigenous sediments, sands, and basalts.
A unidirectional acoustic focusing device with a group of three electrodes
Authors: Toda Kohji
Published: October 2005

A unidirectional device for acoustic focusing has been devised. The transducer consists of a group of three electrodes deposited on two surfaces of a thin piezoelectric ceramic plate. One of them is used as a common earth electrode and is on the substrate surface in contact with water. The others are interdigital electrodes on the other surface. The design and basic focusing properties of the device are described.
Distinctive characteristics of underwater calls of the harp seal, P
h
o
c
a g
r
o
e
n
l
a
n
d
i
c
a, during the breeding season
Authors: Watkins William A. , Schevill William E.
Published: October 2005

Underwater calls of the harp seal, Phoca groenlandica, from the early March whelping and breeding season (1967, Gulf of St. Lawrence) were analyzed. Seventy-five percent of the seal calls were characterized by increasing amplitude and/or increasing frequency (Hz) components. In addition, 94% of the calls were repetitive. These features contrasted sharply with the general features of ambient noise, and provided a distinctive quality to the harp seal calls that could be used to recognize the reproductive herd at a distance.
Acoustic correlates of perceived sexual identity in preadolescent children’s voices
Authors: Bennett Suzanne , Weinberg Bernd
Published: October 2005

This project was undertaken to provide information about the sexual characteristics of preadolescent children’s voices. In one series of experiments, perceptual judgments of sexual identity were obtained in response to 73 children’s productions of isolated whispered and normally phonated vowels, normally spoken sentences, and sentences spoken in a monotonous fashion (Bennett and Weinberg, 1978). The purpose of this portion of the project was to describe certain acoustic and temporal characteristics of these children’s speech samples, and to assess the relationship of these variables to perceptual judgments of sexual identity. Sexual differences in the frequency location of vocal tract resonances were significantly correlated with listener judgments of child sex in all four utterance conditions. The origin of the observed differences in vocal tract resonance characteristics is discussed with reference to possible sexual differences in vocal tract size as well as certain articulatory behaviors. Average fundamental frequency was significantly related to listeners’ sex identifications in two utterance conditions. However, the influence of this variable was considerably less pronounced when compared to vocal tract information. Although certain measures of fundamental frequency variability (mean duration of level inflections and the rate of frequency change associated with upward shifts) were significantly related to perceptual measures of sexual identity, these cues were also interpreted to play a secondary role in defining maleness and femaleness in these children’s voices.
Transmission and reception of short ultrasonic pulses by circular and square transducers
Authors: Hayman A. J. , Weight J. P.
Published: October 2005

The transient fields of circular and square wide-band (1–5 MHz) ultrasonic transducers have been studied in water. Transmission and reception of short pulses have been observed using a small (150 μm) wide-band probe as both receiver and transmitter. Transmit-receive mode results from a small target have also been considered. Detailed comparisons with the theoretical waveforms for an ideal transducer (pistonlike in transmission and pressure-sensitive in reception) exhibit generally good agreement. The principle of reciprocity between transmission and reception has been verified. Discrepancies from pistonlike behavior, most marked at short ranges near the axis of each transducer, have been shown by schlieren observations to be caused by an extra (’’head’’) wave which originates from a plate wave propagating laterally across the face. It is concluded that nearfield pulse echo results must be interpreted with some circumspection.
A pistonless Stirling engine—The traveling wave heat engine
Authors: Ceperley Peter H.
Published: October 2005

The propagation of acoustical waves through a differentially heated regenerator results in gas in the regenerator undergoing a Stirling thermodynamic cycle. One direction of wave propagation results in amplification of the waves and conversion of thermal energy into acoustical energy. The opposite direction results in acoustical energy being used to pump heat. The ideal gain and maximum energy conversion rates are derived in this paper. Low power gain measurements were made which verify the derived gain equation. Practical engines and heat pumps using this principle are discussed.
Multi-obstacle acoustic scattering in the simple source formulation with accuracy checks
Authors: Sorensen Lawrence
Published: October 2005

The simple source formulation is extended to the case of several smooth, rigid obstacles of arbitrary shape. Numerical calculations are presented for scattering by two circular cylinders and by two elliptical cylinders. Results are checked by use of both the reciprocity principle and the optical theorem and are found to be quite good in all cases.
Optimum threshold crossings and time-window validation in threshold pure-tone computerized audiometry
Authors: Harris J. Donald
Published: October 2005

Two versions of the ’’10 dB down–5 dB up’’ rule were computerized: (1) with a ’’lax’’ time-window response validation in which a subject had to press and release a button within the window of 15–3750 ms after onset of a 1-s tone in his earphone (this was designed to simulate the condition often found in manual audiometry) and (2) with a ’’strict’’ condition in which he had to respond within 60–795 ms after onset of the tone and release the button within 15–750 ms following the tone. A threshold-seeking run was continued using 5-dB steps until the threshold had been crossed six times. With 24 subjects it was found that 13 of 288 runs did not yield the ’’ASHA’’ criterion (three ascending series ending on the same hearing level (HL), out of any six or fewer consecutive series), but of these 13 runs all but one run did meet the ’’ANSI’’ criterion (two ascending series ending on the same HL, out of any three or fewer consecutive series). The ANSI Hearing Threshold Levels (HTL’s) were as reliable on test–retest as the ASHA and yielded essentially the same means. An ANSI HTL was established within four or fewer ascending series for 95% or more of the runs, while an average of five extra stimuli was needed to pursue the run until an ASHA HTL was achieved (a savings of nearly 5 min per person). It was recommended that the ANSI criterion for HTL be adopted for many audiometric situations, that a maximum of four ascending series be completed in any single threshold-seeking run, and that rather strict time windows be set within which onset and offset responses may register.
Comments on ’’On errors in some papers on array processing’’ [J. Acoust. Soc. Am. 65, 530–531 (1979)]
Authors: Carter G. Clifford
Published: October 2005

It is shown that the author’s work contains no known errors at this time and that there appears to be no discrepancy between his work and that of Hannan and Thomson (1973).
Reply to C. S. Clay’s ’’Comments on ’Array gain of a broadside vertical line array in shallow water’ ’’ [J. Acoust. Soc. Am. 66, 1548–1551 (1979)]
Authors: Buckingham M. J.
Published: October 2005

The author responds to Clay’s comments regarding the plane-wave representation of the noise field and the choice of unshaded array.
Numerical calculation of the mutual impedance between pistons in a plane wall
Authors: Thompson Stephen C.
Published: October 2005

Calculation of the mutual impedance between two plane pistons in an infinite plane baffle involves a fourfold integration over the areas of the two pistons. In general, all of these integrations must be done numerically. However, for simple piston shapes, a change of variable can reduce two of the integrations to triviality leaving only two to be computed numerically. Results are presented for half-wavelength-diameter circular pistons and half-wavelength-dimension square pistons.
Signal detection in computer-synthesized noise
Authors: Sorkin R. D. , Woods D. D. , Boggs G. J.
Published: October 2005

Human observers detected sinusoidal and pulse-train signals in noise derived from two computer-synthesized sources and from a Gaussian noise source. The synthesized noise stimuli were generated from sequences of pulses whose amplitudes were drawn from two divergent types of probability distributions: a centrally peaked distribution and a bimodal distribution. No differences in the detectability of signals in these noise stimuli were evident at pulse rates of 1000, 2000, 4000, or 10 000 Hz. Subjects could not discriminate between the two types of computer-generated maskers at any pulse rate. The data support a spectrum-analyzer model of detection in which multiband filtering of the input smooths the masker energy in each spectral region to approximate the Gaussian case.
The range of spectral integration
Authors: Spiegel Murray F.
Published: October 2005

The results of two complementary detection tasks using digitally synthesized noise are reported. In one experiment the bandwidth of the synthetic noise was varied to reveal the region most effective in masking a 1-kHz signal. The bandwidth of the internal filter (’’critical band’’) so measured was about 80 Hz. In another experiment, a wideband noise was used as the masker for a synthetic signal whose bandwidth was varied to determine the maximum effective width of the internal filter. Although some earlier experiments suggest maximum effective widths as small as 180–200 Hz (around 1 kHz), the data reported here indicate the range of spectral integraton extends from the critical band to a maximum width that may exceed 3 kHz. In addition, the good agreement between the two experiments suggests a new method for estimating critical bandwidths based on the determination of two thresholds: that of a tonal signal in a wideband masker and that of a supracritical-width noise signal in a wider-bandwidth masker.
Optimum turbulent boundary layer induced noise suppression with suboptimum realizations
Authors: Owsley Norman L. , Fay John W.
Published: October 2005

Optimum beamforming of a line array of either two-or three-element closely spaced hydrophone clusters is considered. The objective is the cancellation of convective noise due to the excitation by the turbulent boundary layer. Expressions for array gain using both uniform and optimum cluster-element weighting are obtained. Suboptimum realizations of the optimum cluster-element combining schemes are proposed that suggest simplified hardware implementations.
Analysis of acoustic fill time effects on cylindrical arrays
Authors: Stokes Robert H. , Koehler George A.
Published: October 2005

When a plane acoustic wave impinges on a cylindrical array, the leading edge insonifies the first few elements of the array. As the wave front continues past the leading edge of the cylinder, more and more elements are insonified until all elements in the array are insonified. The time between the first and last element to be insonified is called array ’’fill time.’’ For a cylindrical array with a phase-shift beamformer, in which the insonifying pulse length is long compared to the fill time, the resultant beam pattern is essentially the same as a cylindrical array with a delay line beamformer and is approximately the same as a planar array of similar aperture size. Up to this time there has been no detailed description of how the beam pattern is affected when the pulse length and the fill time are approximately the same. This article reports a thorough analysis of array fill time of a cylindrical array; a phase-shift beamformer is compared to a delay line beamformer. The conclusion from this study is that fill time has little effect on the array beam pattern as long as the fill time is no greater than the pulse length.
The determination of acoustic source levels for shallow underwater explosions
Authors: Gaspin Joel B. , Goertner Jean A. , Blatstein Ira M.
Published: October 2005

Pressure–time records from the underwater detonation of 8-, 48-, and 1000-lb explosive charges are presented. These data allow a limited verification of the extrapolation of depth dependent parametric relationships for the pressure–time waveform from deep to shallower sources. Time–domain deconvolution of the data to remove the effects of surface reflection is demonstrated. Similar methods are effective for the pressure histories in which cavitation is present or absent. The accuracy of the method is dependent on the signal-to-noise ratio in the data and on the relative arrival time of the surface reflected shock wave. Previously reported source energy levels have been scaled to the conditions of this data set. These scaled values generally agree with the mean energy levels derived from the data for each combination of charge weight and depth to within 1 to 2 dB.
Directional spectral spreading in randomly inhomogeneous media
Authors: McCoy John J. , Beran Mark J.
Published: October 2005

The redirection of the energy flux in an acoustic signal due to random volume scatter can be described by a radiative transport theory. We consider and compare three such theories, differing one from another in the form of the beam pattern of the incrementally scattered energy, sometimes referred to as an effective scattering cross section. Two of the three theories (termed here quasi-isotropic and highly anisotropic) have already received some attention in the acoustics literature. The third (termed here exact) contains the other two as limiting approximations. The comparison is both analytical and numerical; the numerical phase accomplished for an illustrative acoustic experiment carried out in a canonical environment. The results emphasize the importance of the high anisotropy of the sound-speed fluctuations caused by internal waves on the redirection of energy flux measured in a vertical plane.
An examination of multipath processes in a range dependent ocean environment within the context of adiabatic mode theory
Authors: Rutherford Steven R.
Published: October 2005

An extension of the work by Tindle and Guthrie, allowing extraction of ray path information within the context of adiabatic mode theory, has been carried out. The purpose of this extension is to examine the adiabatic solution with respect to the process of multipath conversion due to a sloping bottom. Examples are given which compare ray traces performed by conventional means and ones performed within the context of adiabatic mode theory for upslope propagation in an isovelocity, wedge shaped ocean. The agreement is seen to be quite good even up to bottom slopes as high as 10°.
The significance of beam pattern side lobes in fluid flow measurement
Authors: Sullivan Edmund J. , Kemp Kenneth A.
Published: October 2005

Use of idealized equivalent beam patterns which neglect angular dependence and side lobe structure can lead to errors when interpreting the results of farfield fluid flow measurements. A computer model has been developed which allows estimation of long time average spectra for bistatic transducer configurations. The program is described and computed spectra are discussed for selected mean and fluctuating flows at two beamwidths for a simple geometry in a medium with uniform volume scattering strength. It is demonstrated for this case that, where spectral spreading is dominated by mean flow, the angular dependence and side lobe structure cannot be neglected, whereas for dominant fluctuating flow, idealized beam pattern models are adequate.
Vibration isolation: Use and characterization
Authors: Snowdon John C.
Published: October 2005

The results of a search and critical evaluation of the literature pertinent to both the use and the characterization of the performance of antivibration mountings for the control of noise and vibration are described. First to be discussed are the static and dynamic properties of rubberlike materials that are suited for use in antivibration mountings. This is followed by analyses of the simple (one-stage) mounting system and its subsequent, impaired performance when second-order resonances occur either in the isolator (wave effects) or in the structure of the mounted item itself (nonrigid supporting feet). A discussion is then given of the performance of the compound or two-stage mounting system which possesses superior isolation properties for high frequencies. Next, the four-pole parameter technique of analysis is described and applied, in general terms, to the characterization of the performance of an antivibration mounting with wave effects for the cases where either the supporting foundation or mounted item are nonrigid. The methods adopted for the direct measurement of antivibration-mounting performance are described, followed by an explanation of how this same experimental determination of transmissibility can also be made using an indirect measurement technique based upon four-pole parameter analysis considerations.
A low-cost high-performance ultrasonic amplifier for directly driving solid-dielectric capacitance speakers
Authors: Mitz A. R. , Pottala E. W.
Published: October 2005

The authors describe a low-cost ultrasonic amplifier suitable for animal studies. The amplifier delivers 100 V to a solid-dielectric loudspeaker at 100 kHz, with a 2 V peak-to-peak drive. It uses a quasicomplementary, symmetry transistor output stage with short circuit protection. The authors also discuss the problem of identifying crossover distortion while driving a capacitive load.
The effect of timing errors on the intelligibility of deaf children’s speech
Authors: Osberger Mary Joe , Levitt Harry
Published: October 2005

The purpose of this study was to quantify the effect of timing errors on the intelligibility of deaf children’s speech. Deviant timing patterns were corrected in the recorded speech samples of six deaf children using digital speech processing techniques. The speech waveform was modified to correct timing errors only, leaving all other aspects of the speech unchanged. The following six-stage approximation procedure was used to correct the deviant timing patterns: (1) original, unaltered utterances, (2) correction of pauses only, (3) correction of relative timing, (4) correction of absolute syllable duration, (5) correction of relative timing and pauses, and (6) correction of absolute syllable duration and pauses. Measures of speech intelligibility were obtained for the original and the computer-modified utterances. On the average, the highest intelligibility score was obtained when relative timing errors only were corrected. The correction of this type of error improved the intelligibility of both stressed and unstressed words within a phrase. Improvements in word intelligibility, which occurred when relative timing was corrected, appeared to be closely related to the number of phonemic errors present within a word. The second highest intelligibility score was obtained for the original, unaltered sentences. On the average, the intelligibility scores obtained for the other four forms of timing modification were poorer than those obtained for the original sentences. Thus, the data show that intelligibility improved, on the average, when only one type of error, relative timing, was corrected.
The elastic problem of the flattened-cylinder type of underwater acoustical compliance element
Authors: Shashaty A. J.
Published: October 2005

Sealed tubes containing a gas are often used in oil-filled underwater transducers to provide extra acoustical compliance beyond that of the oil. One type consists of a flattened circular cylinder. An analysis of this family of pressure release tubes is made to provide expressions for the three important characteristics: (1) the compressibility, (2) the pressure at which stress failure of the material occurs, and (3) the pressure at which the two flattened sides come together, ending the usefulness of the device. These quantities are calculated for a particular tube as an example. The effect of initial pressurization is included. Pressurized tubes were used in a transducer test. Fair agreement is found between measured shift in transducer resonant frequency with depth, and the shift calculated from compressibility change with depth.
Stress and deformation analysis of an acoustical compliance tube for use in underwater sound projectors
Authors: Shashaty A. J. , Kruchten H. M.
Published: October 2005

To increase the compressibility of the oil chamber in large, oil-filled underwater transducers, small, sealed, gas-filled, hollow vessels have been used. For these vessels compressibility, coupled with strength, is needed. The stress and deformation problem of the noncircular cylinder under pressure loading is considered. Equations are developed for the volume change, the maximum stress, and the shape change. The equations are applied to a particular shape of flattened cylindrical tube, called the ’’dogbone’’ because of its cross-sectional outline. A specific practical case is worked out numerically for each of two different metals making up the tube.
A saturated parametric acoustic receiver
Authors: Moffett Mark B. , Konrad William L. , Nelson Joseph L. , Lockwood James C.
Published: October 2005

An analysis is presented for a saturated parametric acoustic receiver that is based on the fact, first derived by Fenlon for low-amplitude waves [J. Acoust. Soc. Am. 51, 284–289 (1972)], that saturation loss for the sum- and difference-frequency components is essentially the same as that of the pump frequency alone. After extension of this result to high-amplitude waves, the theory of Rogers, Williams, and Barber [Nav. Res. Lab. Rep. 7484 (29 December 1972)] is then modified to account for saturation. Experimental data showing the validity of this approach are presented.
A geometric acoustics approach to the study of sound propagation in ducts containing sheared flows
Authors: Grimm Denny W. , Hurst C. J.
Published: October 2005

Geometric acoustics has been used to study the propagation of sound waves in a homogeneous moving medium with sheared flow bounded by the hard walls of a duct. Differential equations describing the ray trajectories and the spreading losses along each ray were developed and solved numerically for a range of centerline Mach numbers and shear boundary-layer thicknesses. Results were obtained which show the effects of upstream and downstream sound propagation on the ray paths. A method was also developed to allow the calculation of intensity loss profiles at specified downstream cross sections of the duct.
Spectral properties of fricative consonants in children
Authors: Pentz Arthur , Gilbert H. R. , Zawadzki Paul
Published: October 2005

Twenty-one preadolescent children were asked to produce stimulus words with the fricatives /f/, /v/, /s/, /z/, /ℱ/, and /-/ in various phonetic environments. Results indicated that the major resonances were higher than values reported for both male and female adult speakers. Also significant differences existed among the major resonances of the consonants studied.
On fiber-optic hydrophone noise-equivalent pressure
Authors: Stanton T. K. , Pridham R. G. , McCollough W. V. , Sanguinetti M. P.
Published: October 2005

A recently published mathematical model of a fiber-optic hydrophone by Shajenko et al. [J. Acoust. Soc. Am. 64, 1286–1288 (1978); 66, 1557 (E) (1979)] implies that the limiting noise-equivalent pressure depends on the photodetector gain. Further analysis shows that the gain term in the equation for the noise is exactly cancelled out by another term also appearing in the equation. The model is rederived in this paper where it is shown that this dependence does not exist. The resulting expression for noise-equivalent pressure is consistent with the results presented in the latter of the references cited above.
Speech perception in early infancy: Perceptual constancy for spectrally dissimilar vowel categories
Authors: Kuhl Patricia K.
Published: October 2005

While numerous studies on infant perception demonstrate the infant’s ability to discriminate individual speech-sound pairs, very few demonstrate the infant’s ability to recognize the similarity among phonetic units when they occur in different phonetic contexts, in different positions in a syllable, or when they are spoken by different talkers. In two studies, six-month-old infants demonstrated the ability to distinguish two spectrally dissimilar vowel categories (/a/ and /i/) in which the vowel tokens were generated to simulate tokens produced by a male, a female, and a child talker. In experiment I, the infants were initially trained to discriminate the /a/ and /i/ tokens produced by the computer-simulated male voice. They were then gradually exposed to a number of novel tokens in a progressive transfer-of-learning task. In experiment II, the infants were initially trained to discriminate the same vowel contrast, but were then immediately tested with all of the tokens in both vowel categories. In both experiments the infants demonstrated rapid transfer of learning from the traning tokens produced by the male talker to the tokens produced by female and child talkers. Both experiments provide strong evidence that the six-month-old infant recognizes acoustic categories that conform to the vowel categories perceived by adult speakers of English.
Some effects of deafness on the generation of voice
Authors: Monsen Randall B. , Engebretson A. Maynard , Vemula N. Rao
Published: October 2005

Glottal volume–velocity waveform data were collected from twenty male and female hearing-impaired adolescents by means of a reflectionless tube. The subjects each provided samples of phonation in normal- and soft-voice modes and in a three-syllable word with primary stress on the medial syllable. Analysis of the data, in comparison with characteristics of phonation produced by normally hearing subjects, indicates that deafness affects primarily the time-varying characteristics of the glottal source. Among the hearing-impaired subjects, the following abnormalities were noted: diplophonia and creaky-voice episodes at the onset or middle of phonation, and irregular patterns of change in the frequency and intensity of the glottal waveform. For some subjects, the period-to-period changes of frequency and intensity may be greater than normal. For the hearing-impaired subjects, the shape of the isolated glottal pulse and its spectrum are similar or identical to normal, while striking abnormalities may be seen in the way the glottal pulse changes over time. The effect of deafness is thus that it may prevent a speaker from learning the phonatory consequences of the muscular gestures which maintain and alter vocal-fold tension and subglottal air pressure dynamically in the production of voice.
Analysis of stop consonant production errors in developmentally dysphasic children
Authors: Stark Rachel E. , Tallal Paula
Published: October 2005

The speech production skills of 12 dysphasic children and of 12 normal children were compared. The dysphasic children were found to have significantly greater difficulty than the normal children in producing stop consonants. In addition, it was found that seven of the dysphasic children, who had difficulty in perceiving initial stop consonants, had greater difficulty in producing stop consonants than the remaining five dysphasic children who showed no such perceptual difficulty. A detailed phonetic analysis indicated that the dysphasic children seldom omitted stops or substituted nonstop for stop consonants. Instead, their errors were predominantly of voicing or place of articulation. Acoustic analyses suggested that the voicing errors were related to lack of precise control over the timing of speech events, specifically, voice onset time for initial stops and vowel duration preceding final stops. The number of voicing errors on final stops, however, was greater than expected on the basis of lack of differentiation of vowel duration alone. They appeared also to be related to a tendency in the dysphasic children to produce final stops with exaggerated aspiration. The possible relationship of poor timing control in speech production in these children and auditory temporal processing deficits in speech perception is discussed.
Psychophysical frequency resolution in the cat as determined by simultaneous masking and its relation to auditory-nerve resolution
Authors: Pickles J. O.
Published: October 2005

Critical bandwidths were measured behaviorally at 1 and 2 kHz by simultaneous masking in four cats. Three methods were used. They were (i) the masking of a tone by noise of variable bandwidth, (ii) the masking of a narrow-band signal by two tones, and (iii) the masking of a tone by noise of rippled spectrum. The three methods agreed closely and gave a mean critical bandwith of 410 Hz at 1 kHz and 690 Hz at 2 kHz. These values were about three times as great as the electrophysiologically-determined effective bandwidths of single fibers of the auditory nerve at the same frequencies, both as measured in other animals, and in one of the animals that had been tested behaviorally as well. Psychophysical tuning curves were also determined behaviorally; in contrast, they agreed closely with auditory-nerve fibers in both bandwidth and slope. The results suggest that the critical band as measured by simultaneous masking is not a close relation of the frequency-threshold curve of auditory-nerve fibers, but that the psychophysical tuning curve possibly may be. Possible reasons and implications are discussed.
Analysis of the vibratory excitation of gear systems. II. Tooth error representations, approximations, and application
Authors: Mark William D.
Published: October 2005

The second part of a theory is presented for predicting the vibratory excitation of gear systems from fundamental descriptions of gear tooth elastic properties and deviations of tooth faces from perfect involute surfaces. The first part of the theory [J. Acoust. Soc. Am. 63, 1409–1430 (1978)] provides expressions for the Fourier-series coefficients of the vibratory excitation, which was shown to be described by the static transmission errors of all pairs of meshing gears in a system. The present paper provides expressions for these Fourier-series coefficients in terms of easily interpreted gear tooth metrics that are readily evaluated from tooth-face measurements. Detailed results are given for rectangular tooth-face contact regions using two-dimensional Legendre polynomial expansions of local tooth-pair stiffnesses and stiffness–weighted deviations of tooth faces from perfect involute surfaces. A rigorous transfer function approach is developed that permits separation of the effects of gear tooth errors and gear design parameters, thereby permitting independent assessment of the effects of gear design parameters on the vibratory excitation. The theory is applicable to both helical and spur gears and is illustrated using measurements of tooth-spacing errors and tooth profiles obtained from a pair of spur gears.
Vibration of a plate having a circular inside edge and a cornered outside edge consisting of arcs
Authors: Nagaya Kosuke
Published: October 2005

This paper is concerned with a transverse vibration problem of a thin plate having a circular inside edge and a cornered outside edge consisting of some arcs. The classical plate theory is applied and the eigenvalue problem of the plate is solved by the use of the exact solution of the equation of motion which satisfies the inner boundary conditions. The boundary conditions at the outer edge are satisfied by means of the Fourier expansion method. Numerical calculations are carried out for a plate having a clamped circular inside edge and a free outer one consisting of three arcs. Experimental results are also given as an additional check of this analysis.
Subharmonic responses in liquid helium
Authors: Carey R. F. , Rooney J. A. , Smith C. W.
Published: October 2005

We report measurements of the subharmonic responses of liquid helium to ultrasound in the temperature range 1.3 K<T<2.5 K at applied frequencies of 0.3, 1.0, 2.8, and 10 MHz. Experimental results are compared in detail to the oscillating bubble model of Eller and Flynn and to predictions based upon parametric amplification. We show that the subharmonic response in liquid helium, below the superfluid transition, is directly associated with bulk turbulence. Visualization of the subharmonic response by light diffraction demonstrates that it can be a sustained and coherent bulk effect.
Viscous attenuation of sound in saturated sand
Authors: Hovem Jens M. , Ingram Greg D.
Published: October 2005

Based on Biot’s theory for the propagation of sound in a fluid-saturated porous medium, the viscous attenuation of sound has been studied both theoretically and experimentally. It is shown that the important dynamic parameters can be derived from a knowledge of the permeability, grain size, and porosity. Measurements in uniform sized beads show attenuation and velocity dispersion as a function of frequency in agreement with the theory. A comparison between theoretical viscous attenuation and earlier reported measurements indicates that viscous losses may be of significant importance for higher frequencies in sands of high permeability.
Electromagnetic field reciprocity applied to the excitation and detection of elastic waves in an electromagnetic cavity resonator
Authors: McNab A. , Richter J.
Published: October 2005

This paper discusses the generation and detection of acoustic waves in a piezoelectric material by cavity excitation. By invoking electromagnetic field concepts whereby the acoustic waves appear as equivalent current sources, the reciprocal nature of both problems can be proved. Also, from a knowledge of the cavity electric field and the acoustic excitation vector, the detected cavity responses can be evaluated, showing that two distinct responses (even and odd) are obtained for differing electric fields on the piezoelectric surfaces.
Predictive and residual encoding of speech
Authors: Makhoul John , Berouti Michael
Published: October 2005

This paper surveys recent developments in adaptive predictive coding (APC) of speech. Prominent among these developments are the use of a three-point pitch predictor, a pitch-adaptive quantizer, entropy coding of the residual, and adaptive shaping of the quantization-noise spectrum. APC systems produce high quality speech at around 16 kbit/s; their quality diminishes rapidly at 9.6 kbit/s or less. For those lower data rates, some form of baseband coding system becomes desirable. In such systems, a low-frequency baseband is transmitted. The high-frequency regeneration of the excitation spectrum from the baseband is of special importance. Traditional regeneration techniques have used some form of nonlinear distortion (usually rectification) of the baseband, followed by spectral flattening. We introduce a new set of regeneration based on duplication of the baseband spectrum at high frequencies. The audible signal distortions in rectification and spectral folding are compared.