bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective observation of elastic-body resonances via their ringing in transient acoustic scattering
Authors: Howell W. E. , Numrich S. K. , Überall H.
Published: October 2005

Experiments recently carried out at the University of Le Havre, France [G.Maze and J. Ripoche, Rev. Phys. Appl. 18, 319 (1983); J.Acoust. Soc. Am. 73, 41 (1983)] and at the CNRS laboratories, Marseilles, France [C. Gazanhes et al., Rev. CETHEDEC 70, 1 (1982); Acustica 52, 265 (1983)] regarding the scattering of acoustic transients from submerged elastic bodies exhibit in some instances the ringing of individual resonances of such target objects when insonified by tone bursts of long duration. This phenomenon is interpreted in terms of the interference of multiply circumnavigating circumferential wave trains, and its connection with the complex-frequency poles of the scattering amplitude f (ω) is established. The poles are visualized via a contour plot of ‖ f (ω)‖ in the complex-frequency plane.
Piezoelectric properties of calcium-modified lead titanate and its application in underwater transducers
Authors: Rittenmyer Kurt M. , Ting Robert Y. , Henriquez Theodore A.
Published: October 2005

The dielectric and piezoelectric properties of a calcium-modified PbTiO3 ceramic were determined as a function of pressure from 0 to 70 MPa by using an acoustic reciprocity technique. The transverse piezoelectric coefficients (d31, g31) of this material are very small, which results in high values of hydrostatic gh (=g33+2g31) and dh (=d33+2d31) constant. Consequently, the material is considerably more sensitive than lead zirconate titanate (PZT). Measurements of the resonance properties of this ceramic indicated that it is suitable for use in a high-frequency underwater transducer. Prototype transducers were designed and constructed. The free-field voltage sensitivity was measured over the frequency ranges 1–100 kHz and from 200 kHz–2 MHz. The results of these measurements are compared with those obtained from existing high-frequency hydrophone standards. Since this material is a volume expander, it is very useful for electroacoustic transducer applications.
Comparison of amplification systems in an auditorium
Authors: Nábělek Anna K. , Donahue Amy M.
Published: October 2005

Intelligibility of speech at two positions in a large auditorium was compared for the public address system (PA) and two assistive listening systems: Frequency modulation of radio frequencies (FM) and modulation of infrared light waves (IR). Listening groups were: (1) normal-hearing adults, (2) hearing-impaired, (3) hearing aid users, (4) elderly, and (5) non-native. Word-identification scores were obtained with the Modified Rhyme Tests. Analysis of variance indicated that the main effects of systems, groups, and listening position were significant. Also significant were the two-way interactions. For all groups, the assistive listening systems provided better scores than the PA system. The difference between the two systems was statistically significant, but very small. It can be concluded that both listening systems provide improved speech intelligibility for various types of listeners.
Consonant influences on vowel duration as a function of speech intelligibility for hearing-impaired individuals
Authors: Whitehead Robert L.
Published: October 2005

The purpose of this investigation was to study the effects of consonant environment on vowel duration for normally hearing males, hearing-impaired males with intelligible speech, and hearing-impaired males with semi-intelligible speech. The results indicated that the normally hearing and intelligible hearing-impaired speakers exhibited similar trends with respect to consonant influence on vowel duration; i.e., vowels were longer in duration, in a voiced environment as compared with a voiceless, and in a fricative environment as compared with a plosive. The semi-intelligible hearing-impaired speakers, however, failed to demonstrate a consonant effect on vowel duration, and produced the vowels with significantly longer durations when compared with the other two groups of speakers. These data provide information regarding temporal conditions which may contribute to the decreased intelligibility of hearing-impaired persons.
Spectrographic voice identification: A forensic survey
Authors: Koenig Bruce E.
Published: October 2005

A survey of 2000 voice identification comparisons made by Federal Bureau of Investigation (FBI) examiners was used to determine the observed error rate of the spectrographic voice identification technique under actual forensic conditions. The qualifications of the examiners and the comparison procedures are set forth. The survey revealed that decisions were made in 34.8% of the comparisons with a 0.31% false identification error rate and a 0.53% false elimination error rate. These error rates are expected to represent the minimum error rates under actual forensic conditions.
Acoustical comparison of three theaters
Authors: Bradley J. S.
Published: October 2005

Three theaters, including both thrust stage and proscenium arch designs, are evaluated using acoustical measures not yet in common use. The unique characteristics of each theater are considered and include a partially covered orchestra pit and a music shell. A computer model is used to estimate the detrimental effects of excessive ceiling lighting holes.
Detection and discrimination of simulated motion of auditory targets in the horizontal plane
Authors: Grantham D. Wesley
Published: October 2005

Three experiments investigated subjects’ ability to detect and discriminate the simulated horizontal motion of auditory targets in an anechoic environment. ‘‘Moving’’ stimuli were produced by dynamic application of stereophonic balancing algorithms to a two-loudspeaker system with a 30° separation. All stimuli were 500-Hz tones. In experiment 1, subjects had to discriminate a left-to-right moving stimulus from a stationary stimulus pulsed for the same duration (300 or 600 ms). For both durations, minimum audible ‘‘movement’’ angles (‘‘MAMA’s’’) were on the order of 5° for stimuli presented at 0° azimuth (straight ahead), and increased to greater than 30° for stimuli presented at ±90° azimuth. Experiment 2 further investigated MAMA’s at 0° azimuth, employing two different procedures to track threshold: holding stimulus duration constant (at 100–600 ms) while varying velocity; or holding the velocity constant (at 22°–360°/s) while varying duration. Results from the two procedures agreed with each other and with the MAMA’s determined by Perrott and Musicant for actually moving sound sources [J. Acoust. Soc. Am. 62, 1463–1466 (1977b)]: As stimulus duration decreased below 100–150 ms, the MAMA’s increased sharply from 5°–20° or more, indicating that there is some minimum integration time required for subjects to perform optimally in an auditory spatial resolution task. Experiment 3 determined differential ‘‘velocity’’ thresholds employing simulated reference velocities of 0°–150°/s and stimulus durations of 150–600 ms. As with experiments 1 and 2, the data are more easily summarized by considering angular distance than velocity: For a given ‘‘extent of movement’’ of a reference target, about 4°–10° additional extent is required for threshold discrimination between two ‘‘moving’’ targets, more or less independently of stimulus duration or reference velocity. These data suggest that for the range of simulated velocities employed in these experiments, subjects respond to spatial changes—not velocity per se—when presented with a ‘‘motion’’ detection or discrimination task.
Loudness summation, masking, and temporal interaction for sensations produced by electric stimulation of two sites in the human cochlea
Authors: Tong Y. C. , Clark G. M.
Published: October 2005

Three psychophysical studies were conducted on two multichannel cochlear implant patients. The first study investigated the amount of loudness summation as a function of the spatial separation between two bipolar electrode pairs in the cochlea. Summation was found to increase in an orderly way with the separation between the two electrode pairs. This observation suggested that loudness was related to the distribution of discharge rate of auditory neurons along the cochlea for electric stimulation, and a model of loudness summation formulated on the basis of a functional relationship between loudness and the discharge rate distribution was proposed. The second study investigated the possibility of estimating the discharge rate distribution by means of masking. The amount of masking was found to decrease in an orderly fashion with the spatial separation between the masker and probe electrode pairs. This pattern of masking is consistent with the physiological and modeling observation that the current and neural discharge rate distributions produced by an electrode pair (masker) in the cochlea are approximately bell shaped with gradually decaying borders. The third study investigated the just-discriminable changes in the temporal delay between two interleaving pulse trains delivered, respectively, to two electrode pairs in the cochlea. Discrimination performance was found to decrease with the spatial separation between the two electrode pairs.
The sound level of the singer’s formant in professional singing
Authors: Bloothooft Gerrit , Plomp Reinier
Published: October 2005

The relative sound level of the ‘‘singer’s formant,’’ measured in a 1/3-oct band with a center frequency of 2.5 kHz for males and of 3.16 kHz for females, has been investigated for 14 professional singers, nine different modes of singing, nine different vowels, variations in overall sound-pressure level, and fundamental frequencies ranging from 98 up to 880 Hz. Variation in the sound level of the singer’s formant due to differences among male singers was small (4 dB), the factors vowels (16 dB) and fundamental frequency (9–14 dB) had an intermediate effect, while the largest variation was found for differences among female singers (24 dB), between modes of singing (vocal effort) (23 dB), and in overall sound-pressure level (more than 30 dB). In spite of this great potential variability, for each mode of singing the sound level of the singer’s formant was remarkably constant up to F0=392 Hz, due to adaptation of vocal effort. This may be explained as the result of the perceptual demand of a constant voice quality. The definition of the singer’s formant is discussed.
The differential and total bulk acoustic scattering cross sections of some human and animal tissues
Authors: Nassiri D. K. , Hill C. R.
Published: October 2005

This paper describes methods that have been developed for the accurate measurement of total and differential bulk acoustic scattering cross sections. Analysis is made of the sources of uncertainty entailed in measurements of this kind and a complete derivation is developed for the angular variation of the interrogated scattering volume. Experimentally determined values of differential scattering cross sections are reported for specimens of skeletal muscle, blood, liver, and secondary tumors arising in liver, obtained in the frequency range 4–7 MHz for scattering angles in the practically attainable range 60°–150° and also at 180° (backscatter). A basis for extrapolating these results to other scattering angles can be derived from a combination of theoretical and experimental considerations, as presented in a companion paper [J. Acoust. Soc. Am. 79, 2048–2054 (1986)]. Based on such extrapolation, values for total scattering cross sections are estimated for the above tissues, the values are compared with determinations by different techniques as reported by other authors, and corresponding estimates are derived for the contribution of scattering processes to total attenuation in the tissues.
The use of angular acoustic scattering measurements to estimate structural parameters of human and animal tissues
Authors: Nassiri D. K. , Hill C. R.
Published: October 2005

Theoretical formulations are developed, based on mathematical models of inhomogeneous continua for the expected angular variation of bulk scattering from human and animal tissues. These results are compared with experimental data on angular scattering from liver, muscle, and blood, reported in a companion paper [J. Acoust. Soc. Am. 79, 2034–2047 (1986)], and deductions are drawn as to the appropriateness of the various models for representing the mechanical structure of the different tissues. On this basis, the experimental data and theoretical formulations are used to derive estimates, appropriate to the frequency range of observation (4–7 MHz), of correlation distance (or effective scatterer spacing) d, the local variabilities of density and compressibility, γρ =Δρ/ρ and γκ = Δκ/κ0, and their ratio γρ/γκ. For blood, liver, and skeletal muscle, the values derived at 6 MHz for d are approximately 5, 55, and 75 μm and for γρ/γκ are 0.5, 0.15, and 0.28, respectively. These results are, in particular, at variance with the commonly made assumption, based on evidence from low-frequency measurements, that the ratio γρ/γκ is sufficiently small that density terms can be ignored in calculations of human tissue scattering.
Acoustical properties of partially reticulated foams with high and medium flow resistance
Authors: Allard Jean-F. , Aknine Achour , Depollier Claude
Published: October 2005

A new method for measuring impedance has been used for evaluating the normal surface impedance of three foams in free field. The results have been interpreted using the Biot theory, the two dilatational waves being taken into account. It has been pointed out from the theory that, for high flow resistance, the ratio of the acoustical velocities of the frame and the air is close to 1 at the surface of the foam. This ratio decreases with flow resistance but is never negligible for the studied foams. For foams with high flow resistance, the contributions of the two waves must be taken into account when calculating the impedance, and a description with only one wave would not be realistic. For foams with medium flow resistance, the one-wave approximation for calculating the surface impedance is a good approximation in the whole range of acoustical frequencies.
Simulation of bottom interacting waveforms
Authors: Knobles David P. , Vidmar Paul J.
Published: October 2005

Current understanding of the acoustic processes occurring in the seafloor is used to develop a detailed ray approach for simulating the received time series of a broadband acoustical signal interacting once with the seafloor. The environment is assumed to be horizontally stratified, and the seafloor is described in terms of a geoacoustic profile. The frequency response is constructed from the superposition of the individual responses of each of the eigenrays. The ray approach includes the effects of reflection from the water–sediment interface, penetration into the sediment, refraction due to a constant compressional sound-speed gradient in the sediment, absorption within the sediment, phase shifts due to caustics, and multipaths. The one-bounce time series is constructed from the inverse Fourier transform of the product of the source spectrum and the eigenray frequency response. As an example application, the one-bounce time series for an explosive source in a deep water environment is calculated and analyzed in terms of acoustical processes. Excellent agreement with measured time series is demonstrated.
Rough surface elastic wave scattering in a horizontally stratified ocean
Authors: Kuperman W. A. , Schmidt Henrik
Published: October 2005

A previously developed boundary perturbation method [W. A. Kuperman, J. Acoust. Soc. Am. 58, 365–370 (1975)] is extended to treat scattering at a randomly rough interface which separates viscoelastic media. This method is then combined with a full wave treatment of sound propagating in a stratified ocean described by a system of fluid and elastic layers [H. Schmidt and F. B. Jensen, J. Acoust. Soc. Am. 77, 813–825 (1985)]. The net result of combining the extended boundary perturbation method with the full wave solution technique is to define a set of effective potentials which, when inserted in the full wave solution algorithm, yield the coherent components of the compressional and shear wave fields which decay with range due to boundary roughness scattering into incoherent compressional and shear waves. A natural outcome of this model is also the option to calculate the coherent reflection coefficient for an arbitrarily arranged layered system of fluid/solid media separated by randomly rough interfaces. Numerical examples of reflection coefficients and sound propagation in an ocean described by a stratified waveguide are presented.
Real-time study of frequency dependence of attenuation and velocity of ultrasonic waves during the curing reaction of epoxy resin
Authors: Rokhlin S. I. , Lewis D. K. , Graff K. F. , Adler Laszlo
Published: October 2005

The frequency dependence of the phase velocity and attenuation of ultrasonic waves were measured as a function of time during the polymerization (curing) reaction of epoxy resins. The phase velocity and attenuation were evaluated from the amplitude and phase spectra of ultrasonic signals transmitted through a layer of curing epoxy resin. The measurements were made in the frequency range of 2–20 MHz. From the experimental data follows an important conclusion: The attenuation coefficient increases linearly with frequency at all stages of the curing reaction from the viscous liquid to the solid state. The slope of the attenuation coefficient as a function of frequency is strongly dependent on the time of cure (degree of cure). The linear behavior of attenuation versus frequency suggests that the attenuation effect cannot be explained by classical viscothermal absorption or relaxation theory. This type of behavior (so-called hysteresis behavior) is poorly understood on the molecular level and was found previously for some highly viscous liquids, for solid polymers, and for biological tissue. The phase velocity data were evaluated from the phase spectrum of the transmitted signal. The ultrasonic velocity changes with time according to an S-shaped curve. It is also moderately dependent on the frequency.
Pressure wave reflections in an organ note channel
Authors: Finch T. L. , Nolle A. W.
Published: October 2005

In this investigation, measurements of windchest pressure, organ pipe sound output, and air velocity into the foot of a small pipe are displayed as functions of time, using a long windchest note channel with a hand-operated pallet valve. For rapid opening of the pallet, the pressure signal advancing along the channel consists of (a) a negative pulse due to the pallet displacement, followed by (b) a rising pressure step of height p, typically 80% to 95% of the supply pressure. When the pressure step is reflected from the rigid far end of the channel, a pressure pedestal of height 2p and duration equal to the double passage time is observed there. With further reflections, the pressure changes continue as damped oscillations which depend in detail upon position in the channel. These results indicate that a long channel must be considered as an acoustic transmission line. An extension tube was also added to the end of the note channel. The pressure attained at the end of the extension tube was nearly 3p (theoretical limit 4p) as a result of reflection from its end in addition to the reflection at the impedance discontinuity between the tube and the note channel.
Model for a compliant tube polymer hydrophone
Authors: Ricketts Donald
Published: October 2005

A mathematical model of the compliant tube polymer hydrophone has been developed, which facilitates the evaluation of its low-frequency electroacoustic sensitivity and maximum operating pressure. Developed by the Naval Underwater Systems Center/New London Laboratory (NUSC/NLL), this type of hydrophone is comprised of the compliant tube (an air-filled tube of flattened oval cross section and closed ends), a plastic spacer plate which attaches to the flattened surface of the tube, and the piezoelectric polymer (PVF2) film. The PVF2 film is bonded to the surface of the plastic plate. It is shown that the sensitivity is enhanced by the use of the spacer, rather than bonding the PVF2 film directly to the flattened surface of the compliant tube. Moreover, there is an optimal spacer thickness that maximizes the hydrophone sensitivity. Numerical results are presented for a steel compliant tube polymer hydrophone. The theoretical model has been applied to the NUSC/NLL steel compliant tube polymer hydrophone, with good agreement between the predicted and experimental values for hydrophone sensitivity and maximum operating pressure.
Two concepts of acoustic radiation pressure
Authors: Beissner K.
Published: October 2005

Two different concepts of the Langevin radiation pressure which are ultimately due to Langevin and Brillouin are discussed. The measurement of the radiation force on an absorber at oblique incidence can be regarded as an experimentum crucis in this respect. Herrey’s experimental result, which is confirmed by the author’s observations, is in favor of Brillouin. Some fundamentals and limitations of our present knowledge of the Langevin radiation force in nonabsorbing fluids are considered.
Electrophysiological evidence for the critical band in humans
Authors: Zerlin Stanley
Published: October 2005

The amplitude of wave V of the auditory brainstem response (ABR) has been found to vary in a manner consistent with the psychophysical critical band data. When the frequency separations between members of a tone pair, displaced symmetrically around some center frequency, exceed some critical value, the amplitude of wave V undergoes an abrupt increase. Specifically, tonal pairs straddling 2 and 4 kHz were studied; abrupt increases in wave V amplitude were generally seen when frequency separations were between 600 and 800 Hz for a center frequency of 4 kHz, and between 200–400 Hz for a 2-kHz center frequency. These electrophysiologically derived estimates are in reasonable agreement with psychophysical values found in the literature.
Auditory filter shapes in subjects with unilateral and bilateral cochlear impairments
Authors: Glasberg Brian R. , Moore Brian C. J.
Published: October 2005

The shape of the auditory filter was estimated at three center frequencies, 0.5, 1.0, and 2.0 kHz, for five subjects with unilateral cochlear impairments. Additional measurements were made at 1.0 kHz using one subject with a unilateral impairment and six subjects with bilateral impairments. Subjects were chosen who had thresholds in the impaired ears which were relatively flat as a function of frequency and ranged from 15 to 70 dB HL. The filter shapes were estimated by measuring thresholds for sinusoidal signals (frequency  f ) in the presence of two bands of noise, 0.4 f  wide, one above and one below  f . The spectrum level of the noise was 50 dB (re: 20 μPa) and the noise bands were placed both symmetrically and asymmetrically about the signal frequency. The deviation of the nearer edge of each noise band from  f  varied from 0.0 to 0.8 f. For the normal ears, the filters were markedly asymmetric for center frequencies of 1.0 and 2.0 kHz, the high-frequency branch being steeper. At 0.5 kHz, the filters were more symmetric. For the impaired ears, the filter shapes varied considerably from one subject to another. For most subjects, the lower branch of the filter was much less steep than normal. The upper branch was often less steep than normal, but a few subjects showed a near normal upper branch. For the subjects with unilateral impairments, the equivalent rectangular bandwidth of the filter was always greater for the impaired ear than for the normal ear at each center frequency. For three subjects at 0.5 kHz and one subject at 1.0 kHz, the filter had too little selectivity for its shape to be determined.
Frequency discrimination as a function of tonal duration and excitation-pattern slopes in normal and hearing-impaired listeners
Authors: Freyman Richard L. , Nelson David A.
Published: October 2005

Frequency difference limens were determined as a function of stimulus duration in five normal-hearing and seven hearing-impaired subjects. The frequency DL duration functions obtained from normal-hearing subjects were similar to those reported by Liang and Chistovich [Sov. Phys. Acoust. 6, 75–80 (1961)]. As duration increased, the DL’s improved rapidly over a range of short durations, improved more gradually over a middle range of durations, and reached an asymptote around 200 ms. The functions obtained from the hearing-impaired subjects were similar to those from normal subjects over the middle and longer durations, but did not display the rapid changes at short durations. The paper examines the ability of a variation of Zwicker’s excitation-pattern model of frequency discrimination to explain these duration effects. Most, although not all, of the effects can be adequately explained by the model.
Temporal integration in two species of Old World monkeys: Blue monkeys (C
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Authors: Brown Charles H. , Maloney Christopher G.
Published: October 2005

Changes in auditory sensitivity as a function of signal duration were studied in two species of Old World monkeys. Testing was conducted under free-field conditions with pure tones 250, 800, 1600, and 4000 Hz in frequency. Test stimuli ranged in duration from 35–2000 ms. The results showed that the temporal integration functions for the blue monkeys were similar to those reported for rhesus monkeys [T. D. Clack, J. Acoust. Soc. Am. 40, 1140–1146 (1966)], but differed significantly from those for mangabey monkeys and human subjects tested in the same apparatus, by the same procedure. Integration functions for humans and mangabeys did not differ. It was concluded that some taxonomic groups of primates exhibit temporal integration times that are much longer than those characteristic of humans, while others do not, and that interspecific differences in temporal integration are not readily related to species differences in their vocal repertoires.
The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part I: Review of previous work and the design of an improved test fixture
Authors: Schroeter Juergen
Published: October 2005

This paper gives a comprehensive progress report on the development of objective methods for measuring the attenuation of hearing protection devices (HPD’s), and focuses on the use of acoustic test fixtures (ATF’s), i.e., artificial heads. While there are many publications on ATF’s for the evaluation of circumaural HPD’s (earmuffs), only one serious attempt to construct an ATF for the evaluation of intra-aural HPD’s (earplugs) could be found. Consequently, no ATF for testing earplugs has been standardized so far, while two standardized ATF’s currently exist for testing earmuffs [see ANSI S3.19-1974 (1975) and ISO/DIS 6290 (1983)]. Both ATF’s are suited, however, only for production testing and are not designed for HPD-type testing. It is believed that both ATF’s do not provide sufficiently high accuracy for HPD-type testing. A new ATF with appropriate circumaural and intra-aural flesh simulations was constructed, including a suitable ear simulator and a cast of an average pinna. Objectives for design and construction of the new ATF are discussed. The effect of using artificial flesh on the insertion loss of earmuffs (max. 5 dB at 125 and/or 250 Hz) and the effect of using a pinna (max. 12 dB lower insertion loss at 2 kHz) were evaluated.
A perceptual model of vowel recognition based on the auditory representation of American English vowels
Authors: Syrdal Ann K. , Gopal H. S.
Published: October 2005

A quantitative perceptual model of human vowel recognition based upon psychoacoustic and speech perception data is described. At an intermediate auditory stage of processing, the specific bark difference level of the model represents the pattern of peripheral auditory excitation as the distance in critical bands (barks) between neighboring formants and between the fundamental frequency (F0) and first formant (F1). At a higher, phonetic stage of processing, represented by the critical bark difference level of the model, the transformed vowels may be dichotomously classified based on whether the difference between formants in each dimension falls within or exceeds the critical distance of 3 bark for the spectral center of gravity effect [Chistovich et al., Hear. Res. 1, 185–195 (1979)]. Vowel transformations and classifications correspond well to several major phonetic dimensions and features by which vowels are perceived and traditionally classified. The F1–F0 dimension represents vowel height, and high vowels have F1–F0 differences within 3 bark. The F3–F2 dimension corresponds to vowel place of articulation, and front vowels have F3–F2 differences of less than 3 bark. As an inherent, speaker-independent normalization procedure, the model provides excellent vowel clustering while it greatly reduces between-speaker variability. It offers robust normalization through feature classification because gross binary categorization allows for considerable acoustic variability. There was generally less formant and bark-difference variability for closely spaced formants than for widely spaced formants. These findings agree with independently observed perceptual results and support Stevens’ quantal theory of vowel production and perceptual constraints on production predicted from the critical bark difference level of the model.
Phoneme boundaries in normal and hearing-impaired ears
Authors: Walden Brian E. , Montgomery Allen A. , Prosek Robert A.
Published: October 2005

Two experiments are reported which explore variables that may complicate the interpretation of phoneme boundary data from hearing-impaired listeners. Fourteen synthetic consonant–vowel syllables comprising a /ba–da–ga/ continuum were used as stimuli. The first experiment examined the influence of presentation level and ear of presentation in normal-hearing subjects. Only small differences in the phoneme boundaries and labeling functions were observed between ears and across presentation levels. Thus monaural presentation and relatively high signal level do not appear to be complicating factors in research with hearing-impaired listeners, at least for these stimuli. The second experiment described a test procedure for obtaining phoneme boundaries in some hearing-impaired listeners that controlled for between-subject sources of variation unrelated to hearing impairment and delineated the effects of spectral shaping imposed by the hearing impairment on the labeling functions. Labeling data were obtained from unilaterally hearing-impaired listeners under three test conditions: (a) in the normal ear without any signal distortion; (b) in the normal ear listening through a spectrum shaper that was set to match the subject’s suprathreshold audiometric configuration; and (c) in the impaired ear. The reduction in the audibility of the distinctive acoustic/phonetic cues seemed to explain all or part of the effects of the hearing impairment on the labeling functions of some subjects. For many other subjects, however, other forms of distortion in addition to reduced audibility seemed to affect their labeling behavior.
Coaxial circular array: Study of farfield pattern and field frequency responses
Authors: Chakraborty Bishwajit
Published: October 2005

A theoretical analysis of vertical farfield patterns for a coaxial circular array of 24 discrete circular radiators has been performed. The narrowest beamwidth (2°) was obtained at an operating wavelength of 0.5λ. A sharp pattern and decreasing directive indices with an increase in the operating wavelength established the suitability of such array geometry for underwater bathymetric applications.
Articulatory asymmetries
Authors: Hamlet Sandra L. , Bunnell H. Timothy , Struntz Brian
Published: October 2005

Tongue contact patterns for /s/ and /l/ were investigated using dynamic palatography. Both spatial and temporal asymmetries were commonly found extending into the vocalic transitions for these consonants. Implications for the adequacy of tongue motion data taken in a single midsagittal plane are discussed, as well as for articulatory interpretation of speech signals and speaker recognition applications.
Visual feedback during speech production
Authors: Tye-Murray Nancy
Published: October 2005

The question of whether visual information can affect ongoing speech production arises from numerous studies demonstrating an interaction between auditory and visual information during speech perception. In a preliminary study, the effect of delayed visual feedback on speech production was examined. Two of the 13 subjects demonstrated speech errors that were directly related to the delayed visual signal. However, in the main experiment, providing immediate visual feedback of the articulators did not diminish the effects of delayed auditory feedback for 11 speakers.
Fundamental frequency patterns during spontaneous picture description
Authors: Anderson Steven W. , Cooper William E.
Published: October 2005

This study was conducted to determine if fundamental voice frequency (F0) decreases throughout the course of spontaneously produced sentences, and if so, to compare the declination pattern associated with spontaneously produced sentences to the declination pattern which is reliably found when speakers read isolated sentences aloud. A picture description task was used to elicit original sentences of the speakers’ own formulation while still providing considerable experimental control over the semantic content and syntactic structure of the sentences. Five speakers each formulated and produced five sentences in the picture description task and read aloud five matched sentences. F0 declination reliably occurred in one- and two-clause sentences in spontaneous speech and oral reading. There were no differences between the declination slopes in the two speech modes. We concluded that the domain of F0 declination is not strictly limited to read speech. Comparison of these findings with other recent reports suggests that declination is characteristic of sentences spoken in isolation but not of lengthy passages, independent of whether the speaker is reading aloud or speaking spontaneously.
Comments on ‘‘Transverse vibrations of composite piezoelectric polymer plates’’ [J. Acoust. Soc. Am. 7
7, 1939–1945 (1985)]
Authors: Laura Patricio A. A. , Gelos R.
Published: October 2005

This paper comments on, and analyzes, the case of the vibrating, completely free polymer plate which had been previously studied and discussed by D. Ricketts [J. Acoust. Soc. Am. 77, 1939–1945 (1985)].
Dual-temperature acoustic levitation and sample transport apparatus
Authors: Trinh Eugene , Robey Judith , Jacobi Nathan , Wang Taylor
Published: October 2005

The properties of a dual-temperature resonant chamber to be used for acoustical levitation and positioning have been theoretically and experimentally studied. The predictions of a first-order dissipationless treatment of the generalized wave equation for an inhomogeneous medium are in close agreement with experimental results for the temperature dependence of the resonant mode spectrum and the acoustic pressure distribution, although the measured magnitude of the pressure variations does not correlate well with the calculated one. Ground-based levitation of low-density samples has been demonstrated at 800 °C, where steady-state forces up to 700 dyn were generated.
Near-grazing, low-frequency propagation over randomly rough, rigid surfaces
Authors: Medwin Herman , D’Spain Gerald L.
Published: October 2005

When a low-frequency point source radiates sound close to a low-roughness, steep-sloped, rigid surface, multiple coherent forward scatter creates a boundary wave which propagates with cylindrical divergence and dispersion in the fluid region near the surface. Measurements using laboratory models of surfaces with two- or three-dimensional roughness elements, and a generalization of periodic roughness theory, have been used to develop empirical formulas which describe the amplitude and phase velocity of the coherent boundary wave over natural, randomly rough, rigid surfaces. The formulas are stated in terms of the average height and the rms slope of the steep-sloped roughness elements.
Uncertainties in the cross-spectral method for acoustic intensity under semireverberant conditions
Authors: Villot Michel , Bartel Thomas W. , Yaniv Simone L.
Published: October 2005

Measurements were performed, under semireverberant conditions, to examine uncertainties in the two-microphone cross-spectral method for determining acoustic intensity. Calculations of the pressure gradient error, the error associated with the correction for phase mismatch, and the cross-spectrum random error are discussed. The results of preliminary tests performed under free-field and plane-wave conditions are also presented. The influence of semireverberant conditions on the accuracy of the intensity measurement was studied through the use of a standing-wave tube as a reference sound source. With the tube source placed in a 112-m3 room having reverberation times of about 0.5 s, the radiated power was determined both from the intensity measured inside the tube and from the intensity integrated over a spherical surface enclosing the source. For a measurement system configured to limit the errors listed above to 0.5 dB under free-field conditions, phase correction and random errors of several decibels occurred for measurements in the semireverberant room, when determined for the individual frequency components of the Fourier analysis spectrum. However, the calculated 1/3-octave-band sound power levels agreed within ±0.5 dB for the bands from 160 to 630 Hz. Reductions of the errors by selecting a probe configuration to increase the cross-spectrum phase, increasing the number of time records sampled, and, for measurements within a tube, increasing the tube radius are discussed.
Development of auditory-evoked potentials in the cat. II. Wave latencies
Authors: Walsh Edward J. , McGee JoAnn , Javel Eric
Published: October 2005

Brain stem and forebrain auditory-evoked potentials were studied parametrically during the first 90 postnatal days in unanesthetized kittens using tonal and click stimuli. This paper describes changes that occur in transmission time through the auditory pathway during development by analyses of the maturational time courses of latencies associated with waves of both auditory brain stem responses (ABR’s) and late-occurring auditory-evoked potentials (AER’s), recorded subdermally from the vertex. In response to click stimuli, ABR latencies were found to decay rapidly early in postnatal life and more slowly after the third postnatal week. Those trends were modeled as a two-stage sequential process, with a linear stage occurring between 7 and 18 postnatal days followed by an exponential stage during which adult latencies were achieved. AER latencies changes during development were less complicated, and followed a single-stage exponential time course. When threshold influences were taken into account—that is, when data were adjusted so that sensation level (SL) was constant across age—the latency-maturation curves associated with all ABR waves were adequately described by a single exponential, and latencies recorded from young animals were substantially shorter than latencies associated with the same aged animals when analyses were carried out with constant sound-pressure level (SPL) stimuli across age. In addition, the difference function, generated when isoasymptotic SPL and SL latency versus age functions were subtracted from one another, was also represented by an exponential curve, suggesting that at least two processes underlie the latency decay that occurs during postnatal development. Evoked responses to tonal stimuli throughout development were consistent with the basoapical developmental gradient that is observed anatomically.
Masking effects on ABR waves I and V in infants and adults
Authors: Klein Alan J.
Published: October 2005

The effects of high- and low-pass masking on waves I and V of the auditory brain stem response (ABR) were measured in normal infants who were 2–4 weeks old, and in adults. The signal was a 4-kHz tone pip presented at 86 dB peak equivalent sound-pressure level (p.e. SPL). The masking patterns were different for latency and amplitude criteria, and were also different for infants and adults. The largest difference between infants and adults was seen in the wave I data. Low-pass maskers were very disruptive of the infant wave I, while little or no effect was noted on the adult wave I. High-pass maskers were very disruptive of the adult wave I, while less of an effect was measured on the infant wave I. The wave V data were similar between groups. Cochlear regions which contribute most importantly to wave I extend up to one octave above the frequency of the signal in adults, and to one-half octave above the signal frequency in infants. The reasons for the differences found between infants and adults are uncertain. Two possible mechanisms which can explain these data are differences in peripheral auditory sensitivity, and differences in tuning characteristics of the auditory system.
On the relations of intensity jnd’s to loudness and neural noise
Authors: Zwislocki Jozef J. , Jordan Herbert N.
Published: October 2005

It is shown experimentally that, in contradiction of the fundamental concept of Fechner’s law, the intensity jnd for auditory sinusoidal signals follows loudness, rather than its derivative with respect to sound intensity. The evidence is obtained by comparing the jnd’s of a population with normal hearing to those of a population with hearing loss accompanied by loudness recruitment. Although the recruitment increases the slope of the loudness function, the jnd’s of both populations were found to be practically equal when the loudnesses were equal. The phenomenon is accounted for mathematically by assuming that psychophysically relevant neural noise depends not only on the magnitude of loudness, but also on its derivative with respect to sound intensity. A related derivation accounts for the near miss to Weber’s law.
Level discrimination of tones as a function of duration
Authors: Florentine Mary
Published: October 2005

Difference limens for level [ΔLs (dB)=20 log((p+Δp)/p), where p is the pressure] were measured as a function of duration for tones at 250, 500, and 8000 Hz. Stimulus durations ranged from 2 ms to 2 s, and the stimulus power was held constant. Rise and fall times were 1 ms. The interstimulus interval was 250 ms. At each frequency, three levels were tested: 85, 65, and approximately 40 dB SPL. An adaptive two-alternative forced-choice procedure with feedback was used. For three normal listeners, ΔLs decreased as duration increased, up to at least 2 s, except at 250 Hz. At 250 Hz, ΔL stopped decreasing at durations between 0.5 and 1 s. In a double logarithmic plot of ΔL versus duration, the rate of decrease is generally well fitted by a sloping line. The average slope is −0.28; it is steeper at high levels than at low levels. Because the average slope is shallower than the −0.5 slope predicted for an optimum detector, it may be that fast adaptation of auditory-nerve activity and/or memory effects interfere with level discrimination of long-duration tones. Finally, the ΔLs at 8 kHz decreased nonmonotonically with increasing level.
Psychometric functions for frequency discrimination from listeners with sensorineural hearing loss
Authors: Nelson David A. , Freyman Richard L.
Published: October 2005

Psychometric functions for pulsed pure-tone frequency discrimination were obtained from hearing-impaired listeners at frequencies with normal hearing and at frequencies with mild or moderate hearing losses. The general form of psychometric functions at hearing-impaired frequencies was found to be the same as at normal-hearing frequencies, i.e., d′ was linear with the frequency difference between tones, in Hz. For all but one psychometric function, the addition of an intercept term to the fitting equation did not account for significantly more variance than did the slope term alone. Therefore, it was concluded that psychometric functions for frequency discrimination can be adequately described with only one parameter: the slope of the psychometric function. Deficits in discrimination at hearing-loss frequencies were manifested by more gradual slopes of psychometric functions. Procedures for normalizing psychometric functions are presented, which facilitate comparisons of normal and impaired frequency discrimination data across studies and frequencies. Comparisons of dlf ’s (difference limen for frequency) obtained with adaptive and fixed procedures show a bias toward larger dlf ’s with adaptive procedures, but only at higher frequencies. A discussion of equal-interval and equal-ratio adaptive stepping rules indicates that an equal-ratio rule may be preferable.
Spatial mapping of intracranial auditory events for various degrees of interaural coherence
Authors: Blauert J. , Lindemann W.
Published: October 2005

The broadening and splitting of auditory events in dichotic listening conditions with various degrees of interaural coherence are discussed. By using a psychoacoustical mapping method, it has been possible to observe broadening and splitting for a wide range of stimuli, including broadband pink noise as well as bandpass noises with different relative bandwidths and center frequencies. The spatial extents of the auditory events decrease with increasing center frequencies for bandpass stimuli of constant relative bandwidth. The number of partial events for bandpass stimuli decreases with increasing degrees of interaural coherence. These results are, for example, of interest with respect to auditory spaciousness in architectural acoustics.
Perception of syllable timing by prebabbling infants
Authors: Fowler Carol A. , Smith Mary R. , Tassinary Louis G.
Published: October 2005

Adults hear alternating syllables with isochronous syllable onset–onset times as having a long–short, alternating rhythm when the syllables differ in initial consonant. This occurs because adults attend to syllable-internal events, called the ‘‘P centers’’ or ‘‘stress beats,’’ rather than to syllable onsets. Thus they report that stress-beat aligned speech is isochronous and stress-beat aligned clicks are synchronized with the speech. The question asked here is whether, like adults, infants attend to the timing of syllable stress beats. In experiment 1, infants showed differences in time to habituate to sequences of alternating monosyllables, [bad] and [strad], having two different onset–onset times (onset- and stress-beat-timed) and two different placements of clicks on the syllables (on syllable onsets and on stress beats). Infants habituated more slowly to sequences with clicks on the stress beats than to sequences with clicks on syllable onsets and most slowly of all to stress-beat-timed speech with clicks on the stress beats. To interpret these findings, a second experiment was run using sequences only of the syllable [strad] so that speech timing measured according to onsets and stress beats was the same. Syllables had isochronous timing or a long–short alternating rhythm, corresponding to two possible ways of hearing the stress-beat-timed speech of experiment 1. In addition, two patterns of click placement were compared, uniform and syncopated, corresponding to two ways of hearing the stress-beat aligned clicks of experiment 1. The patterns of sucking times in the two experiments match exactly if stress-beat aligned speech in experiment 1 is identified with the isochronous speech of experiment 2 and the stress-beat aligned clicks of experiment 1 match with the uniformly timed clicks of experiment 2. It is inferred from this correspondence that infants perceive stress beats and stress-beat timing of syllables as adults do.