bluuebunny/crossref_metadata_2025 huggingface dataset:
More on the speech production deficit associated with Parkinson's disease
Authors: Weismer Gary , Kimelman Mikael D. Z. , Gorman Steven
Published: October 2005

For certain patients with Parkinson's disease, we have shown that aspects of vowel production inferred from acoustic analysis are consistent with the akinetic and bradykinetic characteristics of Parkinsonian limb movements [G. Weismer and M.D.Z. Kimelman, J. Acoust. Soc. Am. Suppl. 1 77, S87 (1985)]. Because Parkinsonian dysarthria is often characterized by abnormally fast articulation rates, it is possible that some of the reduced transition extents and rates observed for Parkinson's patients do not reflect directly the nature of the speech movement disorder, but rather are by-products of the abnormally fast rates. To address this issue, vowel transition data will be presented from three groups of speakers (Parkinson's patients, young adults, and geriatrics) who tend to separate on the variable of articulation rate. In addition, the effect of fast rate productions on transition extents and rates in normal speakers will be discussed as a potential simulation of Parkinsonian dysarthria. [Work supported by NIH Award No. NS 13274.]
Long-term average spectra of continuous speech before and after Tomatis andio-vocal training
Authors: Weiss William
Published: October 2005

Three subjects have undergone the Tomatis audio-vocal training, which is a method that filters sidetone for auditory feedback. Long-term average spectra of voiced and whispered speech was taken before and after the training with the following results: (1) Decrease in energy in the 50- to 200-Hz zone; (2) increase in energy in the 800- to 1200-Hz zone; (3) different individual overall energy shifts; (4) larger and wider formantic peaks in the long-term average spectra; (5) increase in global energy; (6) greater pitch and power variability; and (7) increase in average pitch. A discussion concerning the employment of auditory feedback techniques in voice training follows. Future research should determine which psychophysiological characteristics of individuals determine their reactions to auditory feedback. It is also necessary to establish acoustic standards that could indicate desirable directions for voice training.
Frequency and amplitude perturbations of the human voice determined with a reflectionless tube
Authors: Anderson Claire W. , Yonovitz A. , Anderson Wallace L.
Published: October 2005

In this study, the glottal function was obtained through the use of a reflectionless tube. This tube acted as a pseudoinfinite termination of the vocal tract. Male subjects phonated a neutral vowel (schwa) while target matching to tones throughout the vocal range. These waveforms were digitized at 61 440 samples per second for 1 s. Amplitude and frequency perturbations were obtained for cycle-to-cycle variations, as well as a normalized distribution. Spectral analysis of the digitized waveforms provided a simultaneous description of frequency modulation (jitter) and amplitude modulation (shimmer). Frequency perturbations monotonically increased (approximately 1%) with target frequency. Amplitude deviations will be discussed as they relate to the frequency modulation.
High-frequency anderice acoustic backscattering: A simulation model study
Authors: Bishop Garner C. , Mellberg Leonard E.
Published: October 2005

A simulation model that evaluates the backscatter of a high-frequency acoustic pulse from the underice surface of pack ice regions, characteristic of the interior Arctic, has been used to investigate the extent to which various morphologic, geometric, and acoustic parameters, used to describe the underice surface, influence the backscatter. The simulation model utilizes a three-dimensional underice canopy synthesized from two-dimensional acoustic profile data. The large scale scattering features of the underice surface are modeled as first-year ice keels and sloping flat ice regions. The small scale surface structure is modeled as an ensemble of randomly oriented ice blocks. The Kirchhoff approximation is used to evaluate the scattering strength of an individual ice block which, in turn, is used to calculate the scattering strength of the underice surface. The sonar equation is used to calculate reverberation. The parameters used in the model may be divided into four groups: canopy, ice keel, ice block, and acoustic parameters. Parameters used to identify and classify the constituent ice features of the canopy are varied, and it is shown that, for physically reasonable parameters, reverberation is essentially independent of the feature identification and classification criteria. Reverberation is also shown to be largely independent of the parameters that describe only the large scale structure of the ice keel, but is strongly dependent upon parameters that effect the area and spatial orientation of individual ice blocks.
The influence of water-to-ice transition layers on the reflection coefficient and high-frequency acoustic backscatter from an ice keel
Authors: Chin-Bing Stanley A.
Published: October 2005

The physical properties of ice have been included in a plane-wave reflection coefficient calculation that is then used in a model to predict high-frequency acoustic backscatter from an ice keel. Reflection coefficients were computed using a plane-wave model which had parallel layers of varying thicknesses. Each layer was homogeneous in density, compressional velocity and attenuation, and shear velocity and attenuation. Roughness could be included on any layer. A profile of the ice was used [Branch and Posey, J. Acoust. Soc. Am. Suppl. 1 77, S56 (1985)] that allowed a gradual transition from water to multilayered ice. The ice was backed by water to simulate conditions that exist on ice blocks, which form ice keels. An ice-keel model [Bishop et al., J. Acoust. Soc. Am. Suppl. 1 77, S56 (1985)] was modified to accept oblique incidence signals and different types of ice-block rotations. The reflection coefficients were used in the ice-keel model to calculate target strength. Examples are presented that indicate that the reflection coefficient can, at low grazing angles, be highly dependent upon the water-to-ice transition layers. This can give higher returns from the ice-keel model than expected. Moreover, the reflection coefficient's influence on the ice-keel model is dependent upon the type of ice-block rotation used. [Work supported by NAVSEA.]
Source localization in range and depth in an Arctic environment
Authors: Fizell R. G. , Wales S. C.
Published: October 2005

A fixed cw source in the Central Arctic was accurately localized in range and depth using wave-based full-field ambiguity function techniques. The data were taken during the Fram IV experiment, utilizing a vertical array spanning the upper 960 m of a deep-water environment (generally greater than 2800 m) and a high SNR signal from a 20-Hz source at a distance of 270 km from the array, both suspended from the ice cover. The predicted field was computed using a fast field program. Both a linear correlation of the predicted field with the received field and a maximum likelihood method (MLM) estimator correctly localized the source. The MLM estimator produced sidelobes significantly below the main peak, while the linear correlator produced sidelobes sufficiently large to be taken as false targets. The linear processor, however, was less sensitive to mismatch between the predicted and measured field. Array gain for the linear estimator was found to be 2 dB higher than for a conventional plane-wave beamformer.
Resonant scatterer configurations near elastic boundaries
Authors: Tolstoy I.
Published: October 2005

Systems of precisely spaced bubbles, air-filled shells or balloons in water, insonified at frequencies near their intrinsic radial resonance ω0 exhibit true resonant modes. For resonant wavenumber kR (in water) and scatterer radius a, this leads to amplification factors (kRa)−1 above and beyond the similar classical factor due to single scatter, and thus to net pressure amplification of order (kRa)−2 relative to the incident field (i.e., over 120 dB on the intensity scale, on or inside the scatterer). This effect is predicted by formulas for the equivalent source strength B of each scatterer of the system, account being taken of multiple scatter interaction. Whereas for pairs of scatterers, or periodic lattices, B is known to exhibit relatively modest maxima for selected values of x = kl (l being the spacing between scatterers), which had been called resonances [V. Twersky, J. Opt. Soc. Am. 52, 145–171 (1962)], one can show that, under certain conditions, true resonances exist— i.e., in the absence of attenuation, B exhibits real poles. This phenomenon is much enhanced for systems near elastic boundaries for which coupling between scatterers is mediated by surface waves, and doublet or triplet configurations develop spectra of resonant configurations xn at frequencies ωn (the latter being all close to ω0 for a spectrum of scatterer sizes an). [Work supported by ONR.]
Numerical computation of pulse response functions in an oceanic environment with rough surface scattering
Authors: Nghiem-Phu Lan , Tappert Frederick
Published: October 2005

A recently developed split-step Fourier algorithm for solving the parabolic wave equation, exactly with the effects of rough surface scattering included [J. Acoust. Soc. Am. Suppl. 1 77, S102 (1985)], has been used to compute the pulse response functions in an oceanic environment where a surface duct is present, while the surface of the ocean is treated as a randomly rough pressure release boundary. In particular, we have studied the effects of surface roughness characterized by a typical k−3 spectrum parametrized by the rms roughness σ and correlation length L on the pulse response patterns. Coherency of the time domain transmission loss is examined as surface roughness is varied in a manner similar to that discussed by the authors in a study of rough ocean bottom scattering. [Symposium on Ocean-Seismo Acoustics, La Spezia, June 1985.]
High-frequency bottom backscattering in the Arafura Sea
Authors: Jackson Darrell R. , Richardson Michael D.
Published: October 2005

Detailed backscatter and geoacoustic measurements were made at a 1-km2 site in the Arafura Sea, north of Australia. Data were collected in collaboration with the Royal Australian Navy Research Laboratory in May 1984. Sediment geoacoustic and roughness properties were characterized using box core samples, underwater television, stereophotography, and sidescan sonar. Sediments consisted of a silty-clay matrix, mixed with up to 30% whole and broken sand and gravel-sized molluscan shells. X-radiograpbs of the sediment showed fine scale volume inhomogeneities due to burrowing animals and shell fragments. Compressional wave attenuation (65 dB/m at 125 kHz; CV = 47.5%) was much more variable than the sediment/water sound velocity ratio (0.989 at 125 kHz; CV = 0.66%). Backscatter measurements were made over the frequency range of 15–45 kHz and over a wide range of grazing angles. Scattering strength at a 20°-grazing angle ( −27 dB) was independent of frequency. Comparison of measured results with those predicted by physical scattering models suggests that backscattering was primarily due to sediment inhomogeneity. Measurements obtained along a 144-km track showed that this scattering process was remarkably constant over a wide geographic area. [Work supported by NAVSEA 63-R and administrated by NORAD.]
The unreasonable effectiveness of number theory in acoustics
Authors: Schroeder Manfred R.
Published: October 2005

Some of the problems that have occupied Vern O. Knudsen during his long career in acoustics have found surprising answers through applications of number theory, a field usually considered rather abstract even within mathematics. Among these unexpected applications are the distribution of normal modes in rooms, the design of surfaces (“reflection phase gratings”) that optimally diffuse sound, and the construction of new music scales. Another application is the selection of phase angles to minimize the peak factor in waveforms for speech synthesis and sonar. Finally, precision measurements of reverberation and absorption of sound in gases, pioneered by Knudsen fifty years ago [V. O. Knudsen, J. Acoust. Soc. Am. 6, 199–204 (1935)], can be made more robust by using “pings” shaped according to the theory of finite number fields.
Prediction of sound transmission through double-walled systems containing helium
Authors: Raju P. K. , Crocker Malcolm J.
Published: October 2005

Statistical energy analysis (SEA) is applied to study the transmission of random incidence sound waves through two finite independent panels separated by a gap filled with helium. The study was made for the following two cases: (1) glass panes with a cavity, and (2) vinyl panes with a cavity. The analytical SEA model chosen is similar to the one developed earlier by one of the authors [A. J. Price and M. J. Crocker, J. Acoust. Soc. Am. 47, 683–693 (1970)]. The analytical model consists of five linearly coupled oscillator systems, room-panel-cavity-panel-room. Both resonant and nonresonant transmissions have been considered for each wall of the double panel system. Allowance has also been made in the analytical model to include the effects of the absorption in the cavity. The results show that the use of helium instead of air in the gap of the double panel systems shifts the coincidence frequency region to a higher frequency and also increases the transmission loss values.
Development of a new artificial head for impulse noise attenuation measurements of hearing protective devices
Authors: Giguere Christian , Kunov Hans , Abel Sharon M. , Schroeter Juergen , Willmott Glenn , Myers Barry S.
Published: October 2005

While psychoacoustical methods to evaluate the sound attenuation of heating protective devices have been standardized (CSA Z94.2-M1984; ASA STD 1-1975) and proved to be practical for continuous noise, no standard exists for impulse noise. Microphone-based techniques seem to provide the best avenue for the measurement of impulse noise attenuation at the present time. This paper presents our progress in the design of a new artificial head simulating the relevant mechanical and acoustical parameters of the human head influencing the protected and unprotected eardrum sound pressure. These parameters include: (1) the diffraction of sound by the human head, (2) the mechanical impedance of human tissues, (3) the circumaural contours, (4) the external ear features such as pinna, ear canal, and eardrum impedance, and (5) the vibration of the head in the sound field. [Work supported by the Defence and Civil Institute of Environmental Medecine, Canada.]
The dependence of critical level upon duration
Authors: Ward W. Dixon , Henderson Dorisann
Published: October 2005

In the chinchilla, the critical level for single exposures to 700- to 2800-Hz noise of 20 min or longer duration has been found to be between 112 and 120 dB SPL. For example, a 22-min exposure at 120 dB produced considerably more permanent threshold shift, PTS (50 dB at 2000 Hz), and histological damage [80% destruction of the outer hair cells (OHC)] than a 220-min exposure at 112 dB or any single uninterrupted exposure longer than 220 min but equivalent in energy to the 220-min 112-dB exposure (20 dB PTS, 10% OHC destruction). However, in the present experiment, daily exposure for 9 weeks, Monday through Friday, to 40 7.2-s bursts of 120-dB noise spread over an 8-h “workday” (hence with 12 min between bursts) produced negligible PTS and OHC destruction. Clearly, therefore, the critical level depends on duration and temporal pattern, and so regulatory systems governing exposure of workers to industrial noise that put a fixed ceiling on exposure levels regardless of temporal pattern—whether this ceiling be 115 dBA, 130 dBA, or 140 dB peak—will often, if not usually, be incorrect. [Research supported by NIH Grant 12125.]
The effect of impulse intensity and the number of impulses on hearing and cochlear pathology in the chinchilla
Authors: Patterson James H. , Lomba-Gautier Ilia M. , Curd Dennis L. , Hamernik Roger P. , Salvi Richard J. , Hargett C. E. , Turrentine George
Published: October 2005

Forty-one chinchillas, divided into seven groups, were exposed to 1, 10, or 100 noise impulses having peak intensities of 131, 135, 139, or 147 dB. Hearing thresholds were measured in each animal prior to exposure using an avoidance conditioning procedure. Threshold shifts were monitored at regular intervals over a 30-day post-exposure period. A surface preparation of the cochlear sensory epithelia was performed approximately 90 days after exposure. There was generally an orderly relation between the amount of permanent threshold shift and the severity of exposure, and a general agreement between averaged histological data and the audiometric data. Detailed relations between temporary and permanent threshold shift, cochlear pathology, and exposure variables are discussed, as are the implications of these data to the development of exposure criteria.
The “seat-dip phenomenon”: Low-frequency thief plagues concert goers
Authors: Greenberg David A.
Published: October 2005

Sound propagating at grazing incidence over auditorium seats is known to exhibit anomalous attenuation (as much as 20 dB) at low frequencies. This so-called “seat-dip phenomenon,” is predominantly a quarter-wave resonance associated with the height of the seat backs and is on the order of 112 oct wide, centered at about 150 Hz [T. J. Schultz and B. G. Watters, J. Acoust. Soc. Am. 86, 885–896 (1964) and G. M. Sessler and J. E. West, J. Acoust. Soc. Am. 36, 1725–1732 (1964)]. This frequency range happens to correspond to an orchestra's low end (bassoon, horn, trombone, tuba, cello, and string bass) and so the control of the seat dip is an important factor in the communication of orchestral balance. Toward this end, a simple scale modal was built to investigate this complex sound field, particularly that between the seats. Various model configurations were utilized to investigate the sound pressure and intensity fields.
Two-ear correlation in statistical sound fields
Authors: Lindevald Ian M. , Benade A. H.
Published: October 2005

The normalized correlation function R (f), connecting the signals at the left and right ears, was measured in a reverberant room as a function of frequency. Head diffraction effects are made evident by comparing these data to the correlation function predicted and observed for two mikes separated by a headwidth (15 cm) of space and moving in the same room. In contrast to the familiar two-mike sine (δ) correlation (δ — kd), head diffraction gives a two-ear correlation function, which is well described by sine (αδ)/[1 + (βδ)4]1/2, where α = 2.2 and β = 0.5. The dominant effect of head diffraction is to lower fD, the decoupling frequency [first zero of R (f)], to 500 Hz, about one-half the no-head value. The denominator in the fitted correlation function represents the near total independence of the signals at the two ears above fD. Thus, with head diffraction, the variance in a paired-mike room with averaged pressure amplitude estimate at around 500 Hz, is already as small as that obtained sans head only at frequencies above 1200 Hz. [Work supported by NSF.]
A review of the acoustic properties of the Bose liquid 4He and the Fermi liquid 3He
Authors: Rudnick Isadore
Published: October 2005

Between the temperatures of 2.2° and 5.2 °K, 4He is an ordinary liquid and the sound which occurs in it is ordinary sound. At 2.2 °K the lambda phase transition occurs and below Tλ as a result of the Bose-Einstein condensation 4He is a superfluid with a galaxy of sound modes; first through fifth. Superfluidity and the acoustic modes persist as T→0. Their properties and use in determining the superfluid properties of 4He will be discussed. The critical point of 3He is 3.3 °K. It too, undergoes a superfluid transition but at much lower temperatures—at about 2 × 10−3 °K. Both above and below this temperature there is a new sound mode called zero sound. It exists both as a transverse and a longitudinal wave. Evidence that this mode arises because 3He is a viscoelastic liquid will be presented. Zero, first, second, and fourth sound have been observed in the superfluid phases of 3He. [Work supported by ONR.]
Surface acoustic wave investigation of superconducting films by means of the acoustoelectric effect
Authors: Levy Moises
Published: October 2005

The piezoelectric interaction of surface acoustic waves (SAW) with metallic films deposited on a piezoelectric substrate is quenched when the film becomes superconducting. This acoustoelectric interaction should be proportional to the sheet resistivity of the film in the limit where the SAW period is smaller than the acoustoelectric relaxation time. The attenuation coefficient of SAW propagating through superconducting films of granular Pb and NbN has been measured at 700 MHz. In both cases the attenuation is not proportional to the measured dc resistivity of the films. The attenuation remains finite in the superconducting state of the granular Pb film even when the sheet resistivity disappears. This difference is ascribed, with a percolation model, to the fact that the dc current measures the resistance of the whole film while the SAW measures the effective resistance of a sample with dimensions comparable to its wavelength. The attenuation in the NbN film attains its normal value when the temperature increases slightly above the Kosterlitz Thouless transition where antiparallel flux line pairs dissociate, while at this temperature the film resistivity has barely changed from zero. A model has been proposed that ascribes the attenuation to the presence of normal cores in the flux line pairs. [Research supported by Air Force Office of Scientific Research under AFOSR Grant No. 84-0350.]
Ultrasonic propagation in solid H2
Authors: Meyer Horst
Published: October 2005

Besides the loss mechanism from imperfections and dislocations in a periodic lattice, an additional acoustic loss can be predicted from orientational ordering in this molecular quantum solid. Two modifications of H2, namely ortho-H2 (with rotational angular momentum J = 1) and para-H2 (with J = 0) are randomly distributed in this solid, and we label by X the ortho-H2 molefraction. As the temperature decreases, the ortho-H2 molecules, which are coupled by anisotropic electrostatic forces, become orientationally ordered. This situation is similar to the ordering in diluted magnetic system with random distribution of spins. This talk will review the ordering in solid o-H2 p-H2 mixtures, the detection by acoustic and NMR techniques, and the correlation between these two methods. Furthermore, acoustic methods give a sensitive probe to the martensitic hcp→fcc transition that is induced by the ordering for X > 0.53. For lower X, the ordering takes place progressively in the hcp phase. [Work supported by NSF.]
Ultrasonic studies of metallic glasses at low temperatures
Authors: Elbaum C.
Published: October 2005

Amorphous materials, in general, including metallic glasses, exhibit very distinct characteristics at low temperatures (T ≲ 2 K), which are qualitatively quite different from those of their crystalline counterparts. Among these characteristics are unusual ultrasonic propagation features, such as a saturable, amplitude-dependent attenuation, and an “anomalous” temperature dependence of wave velocity. To account for these, as well as various thermodynamic and transport properties of amorphous solids, a phenomenological model developed some time ago, is often successfully used. This model postulates the existence of two-level systems (TLS) that give rise to excitations resulting from quantum mechanical tunneling of some unspecified entity (an atom or group of atoms) between the minima of an asymmetric double well potential. A brief review will be given of earlier work in this area followed by an account of recent ultrasonic studies conducted to probe the properties of metallic glasses, in general, and the features of the TLS model, in particular. Attention will be directed to the search for the specific nature of the as yet unknown tunneling entity of the model.
Freezing of liquids in small pores
Authors: Warner Kevin , Beamish John
Published: October 2005

We have ultrasonically studied the freezing of various cryogenic fluids in a porous solid. By measuring the transverse and longitudinal sound velocities for the empty matrix as well as for the cases of liquid- and solid-filled pores, we could determine both the density of the material in the pores and its contribution to the composite material's elastic moduli. For fluid-filled pores, we find good agreement with the Biot model. Freezing in the pores is observed through changes in the sound velocities. In small pores, considerable super cooling of the liquid occurs and there is hysteresis between freezing and melting temperatures. Possible interpretations of these results in terms of interfacial free energies and wetting of the solid surface by the pore material are discussed. [Work supported by the University of Delaware Research Foundation and by the Research Corporation.]
A comparison of psychophysical tuning curves in simultaneous and forward masking
Authors: Bacon Sid P. , Moore Brian C. J.
Published: October 2005

Threshold for a short-duration pure-tone signal depends upon the signal's temporal position within a longer duration pure-tone masker, particularly for masker frequencies above the signal frequency [Bacon and Viemeister, J. Acoust. Soc. Am. Suppl. 1 76, S75–76 (1984)]. We have extended the previous work to show how this temporal effect influences a common measure of frequency selectivity. Psychophysical tuning curves (PTCs) were measured for a 20-ms, 1-kHz signal presented at 10-dB sensation level and positioned at the beginning, at the center, at the end, or immediately following a 400-ms masker. In simultaneous masking, the PTCs were broadest for the signal at masker onset, and sharpest for the signal at the center; the differences were largest on the high-frequency side. For two of the three subjects, the forward masking PTC was sharper than any of the simultaneous masking PTCs. For one subject, however, there was little difference between the forward and the simultaneous masking PTC with the signal temporally centered. These results indicate that, at least for short-duration signals, the frequency selectivity measured with simultaneous masking PTCs, and the degree of sharpening revealed in forward masking PTCs, depend upon the temporal position of the signal within the simultaneous masker. [Work supported by NIH and MRC.]
Forward masking of single and double component probes
Authors: Fleet Gregory J. , Booth John C.
Published: October 2005

A series of preliminary studies sought to examine the role of temporal information in auditory frequency resolution. A forward masking paradigm was used, similar to that used in measuring psychophysical tuning curves. The masker levels were adapted to just mask a brief (10 ms) low-level signal. In one condition, though, a second signal, presented at near threshold, was added. Therefore, the signal consisted of two frequency components presented simultaneously following the masker. The masker frequencies were 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 kHz. Signal frequencies were 1.0 and 1.5 kHz. The level of the signal components were combinations of 10, 5, and 0 dB SL. The results for the 10/10-dB and 5/10-dB signal combinations were predictable from the single frequency signal studies, but greater masker levels than expected were found in the 0/10-dB SL conditions. Therefore, adding energy to the signal (at levels of “near” detectability), increased the masker-level thresholds much more than found in the single-signal condition. The discussion will focus on the type of information present in the task that could account for this effect. [Work supported by MRC.]
Bandwidth, apparent pitch, and frequency discrimination: Effects with complex harmonic tones
Authors: Creelman C. Douglas
Published: October 2005

Harmonically complex signals which are heard as having low pitch (< 0.3–0.5 kHz) yield superior pitch discrimination compared to equivalent-pitch simple tones. On the other hand, narrow-bandwidth complexes, heard to have pitch more nearly that of a carrier frequency rather than the spacing of sidebands, are discriminated nearly as well as pure tones of equivalent pitch. Frequency discrimination was measured using the PEST adaptive procedure and small logarithmic steps for harmonic spectra with center frequencies in the range 240–4800 Hz, and fundamental frequencies from 60–300 Hz, covering much of the range of musical and voice formants. These data, and a further experiment in which frequency discrimination was measured between wide bandwidth complexes when the signals were of unpredictable amplitude, are considered to rule against a recently published model from Horst et al. [J. Acoust. Soc. Am. 76, 1067–1075 (1984)] which proposed amplitude differences among specific components to be the basis of frequency discrimination. Instead a profile analysis based on activity in the frequency range of cochlear sensitivity is proposed. [Work supported by the Canadian National Science and Engineering Research Council.]
On the effect of amplitude envelope on the pitch of short complex tones
Authors: Rossing T. D. , Houtsma A. J. M.
Published: October 2005

It has been shown that the perceived pitch of a short exponentially decaying sine tone is judged higher than the pitch of a gated sine tone of the same frequency and energy, that the frequency difference for equal pitch is adequately described by the relation Δf = K log f, and that Δf grows monotonically both with exponential decay rate and with intensity [T. D. Rossing and A. J. M. Houtsma, J. Acoust. Soc. Am. Suppl. 1 77, S36 (1985)]. We have now extended the studies to complex tones consisting of two sinusoidal components with frequencies f1 = mf + 50 Hz and f2 = (m + 1)f + 50 Hz, where m equals 3, 4, or 5. Subjects were asked to judge the “low” pitch as well as the pitch of the individual spectral components f1 and f2. We find shifts in f1 are generally less, and shifts in f2 are generally greater than the shifts observed in isolated sine-wave tones of comparable frequencies. Shifts in the perceived pitch of both components f1 and f2 show only slight dependence on the envelope decay rate in contrast to isolated sine-wave tones, where Δf increases monotonically with exponential decay rate. The “low” pitch of the complex is generally found to be 0–1.5% higher than that computed for the first-order pitch shift, and it appears to depend less on envelope decay rate than the pitch of sine-wave tones of comparable frequency. [Work supported by a grant from the Netherlands Organization for the Advancement of Pure Research (ZWO).]
Tectorial membrane—A collagen-based gel?
Authors: Thalmann Isolde , Thallinger Gertraud , Comegys Thomas H. , Thalmann Ruediger
Published: October 2005

According to traditional thinking, the tectorial membrane (TM) is a gel with a matrix of proteins, but containing no collagen. We recently reported patterns of amino acids and proteins of the TM consistent with the presence of substantial amounts of collagen [I. Thalmann et al., J. Acoust. Soc. Am. Suppl. 1 77, S93 (1985)]. Using two-dimensional polyacrylamide gel electrophoresis with extended alkaline range, we have now found that the predominant protein of the TM of the guinea pig virtually superimposes with purified collagen standards. Moreover, peptide mapping of cyanogen bromide digests (“fingerprinting”) results in a pattern closely resembling that of collagen type II. Further procedures for identification and characterization of this protein (effect of collagenase, immunoblotting, etc.) are in progress. At this stage it is not possible to decide to what extent the amino and neutral sugars present in hydrolysates of the TM are part of the alleged collagen molecule. The cupula ampullaris, a vestibular superstructure thought to be analogous to the TM, exhibits a substantially different chemical profile. The functional significance of the findings will be discussed. [Supported in part by NIH.]
Direct measurement of longitudinal movement of tracer in cochlear endolymph
Authors: Salt Alec N. , Thalmann Ruediger , Marcus Daniel C. , Bohne Barbara A.
Published: October 2005

On the basis of morphological studies which show that tracers injected into cochlear endolymph subsequently reach the endolymphatic sac, it has been repeatedly postulated that there is a bulk flow of cochlear endolymph towards the basal turn. However, no study has yet reported the relative contributions of passive diffusion and volume flow to the dispersion of substances in endolymph. We have measured the characteristics of movement of an ionic tracer between the first and second turns of the guinea pig cochlea. Tetramethylammonium (TMA) was chosen as a tracer as it can be readily detected in low concentrations by a potassium-selective microelectrode. The characteristics of TMA arrival monitored in turn II following a minute injection into turn I were compared with those monitored in turn I following injection into turn II. These results were compared with those predicted by a one-dimensional computer model of ionic diffusion in which various rates of volume flow could be incorporated. Our results demonstrate that TMA appears to spread symmetrically in the cochlea. This finding demonstrates that the movement of ions in endolymph is dominated by passive diffusion with almost negligible contribution from bulk flow. [This work supported by NIH.]
The origins of adaptation in the auditory nerve
Authors: Smith Robert L. , Westerman Larry A.
Published: October 2005

In response to stimuli of constant sound intensity, auditory-nerve firing rates are maximum at onset, and then decay or adapt towards a steady-state rate. The early decay appears to be made up of two exponential components, rapid adaptation and short-term adaptation, with time constants on the order of 5 and 50 ms, respectively. A variety of data will be presented and reviewed that generally, albeit indirectly, support the conclusion that both phases of adaptation have a common, synaptic, origin. The data demonstrate the following: adaptation is not present in the hair cell response, adaptation compresses the input-output characteristic, adaptation has an asymmetrical effect on responses to changes in intensity, adaptation does not qualitatively alter response variability, adaptation is minimally affected by stimulus rise time, adaptation is not caused by neural refractoriness, and adaptation is a complex function of sound frequency. A previously described [R. L. Smith and M. L. Brachman, Biol. Cybern. 44, 107–120 (1982)] model of adaptation, based on hypothesized properties of synaptic depletion, is consistent with most of the results. [Work supported by NSF and NIH.]
Tuning in goldfish auditory nerve fibers
Authors: Fay Richard R. , Ream Timothy J.
Published: October 2005

Tuning curves for over 500 saccular nerve fibers were systematically surveyed with 10-Hz resolution between 100 and 2000 Hz using statistically defined spike rate thresholds with an automated tracking procedure. Spontaneous rate (SR), variation in rate, spontaneous type (silent, burst, irregular, and regular), and position of the electrode in the nerve were recorded. Best frequency (BF), best sensitivity (BS), Q 10 dB, and tuning slopes were measured. Units vary considerably in BF and in degree of tuning at a given BF. Four main types of units were identified: BF at or below 150 Hz, BF between 160 and 390 Hz, tuned between 410 and 800 Hz, and tuned between 900 and 1700 Hz. Additional units were found having no BF (essentially flat, or having low-pass characteristics without measurable BF). BS varies over 60 dB with the most sensitive units within 10 dB of behavioral thresholds. The least sensitive units within each type had no spontaneous activity. Within each type, SRs range from zero to over 100 S /S. Average Q 10 dB is 0.75 ranging from 0 to 2. Although units can be selected to illustrate a continuous range of BFs from 100 to 1700 Hz, the units clearly group into the above BF types which are also characterized by different adaptation patterns. In the ventral half of the nerve, fibers with the highest BFs were found medially, and those with the lowest BFs found laterally. [Supported by the NIH.]
A comparison of AP and ABR tuning characteristics in the guinea pig
Authors: Brown Carolyn J. , Abbas Paul J.
Published: October 2005

AP and ABR tuning curves were measured using a forward-masking paradigm in guinea pigs with chronically implanted electrodes. Measurements were made before exposure to wide-band noise and at several intervals after exposure. The noise exposure was sufficient to produce temporary threshold shifts up to 60 dB lasting several days and resulted in a systematic widening of both AP and ABR tuning curves and a reduction in tip-to-tail ratios. No significant differences were found between simultaneously recorded AP and ABR tuning curves as measured by Q10, tip-to-tail ratio, or the slope of the tuning curves. Tuning curves obtained by measuring AP and ABR response latency as a function of masker level, showed similar form and changes with hearing loss to those based on amplitude of response. The similarities between AP and ABR tuning characteristics provide evidence that the ABR is sensitive enough to peripheral changes to be a useful tool in the study of auditory frequency selectivity.
Variations in ABR morphology, absolute latencies, and interpeak intervals due to electrical stimulation in man and guinea pig
Authors: Brown D. D. , Miyamoto R. T.
Published: October 2005

Electical auditory brainstem response (EABR) recordings have been made in 16 human subjects implanted with a single channel intracochlear device, and in 25 guinea pigs (GPs) with a similar intracochlear electrode. Electrical stimulation results in an ABR that differs from its acoustical counterpart. The most prominent change in the EABR is a decrease in absolute latency of all waves amounting to 1.0–1.5 ms in man and 0.6–0.7 ms in the GP. Not all waves have the same latency decrease with electrical stimulation, and this results in a change of some interpeak intervals. This change is more prominant in man (where it affects the I–III intervals) than it is in the GP. The EABR and acoustic morphologies differ; in man this difference is small while in the GP it is quite pronounced. Normative data will be presented and the differences found between electrical and acoustical stimulation will be discussed.
Response characteristics and connections of auditory cortex in squirrels
Authors: Luethke L. E. , Krubitzer L. , Kaas J. H.
Published: October 2005

While several subdivisions of auditory cortex have been determined in cats and monkeys, the organization of auditory cortex in rodents is not well understood. Connections, myeloarchitecture, and response characteristics of clusters of neurons were used to subdivide auditory cortex in grey squirrels, which are rodents with large, well-differentiated brains. These data reveal that primary auditory cortex (AI) is tonotopically organized (high frequencies represented caudomedially, low rostrolaterally), heavily myelinated, and reciprocally connected with multiple locations in the surrounding cortex. Although many neuronal clusters outside of AI are broadly tuned and habituate rapidly, our findings show that some of the surrounding cortex is responsive to auditory stimulation and includes two zones: (1) a rostrolateral (to AI) region which appears to be tonotopically organized and (2) a newly discovered “parietal ventral” somatosensory field which is apparently bimodal. AI is also reciprocally connected with a caudolateral zone which is not responsive to auditory stimuli. These results suggest that auditory cortex in rodents is more complexly organized than previously thought. [Work supported by NIH Grant NS16446.]
Effect of formant transition rate variation on the differentiation of synthesized child and adult /w/ and /r/ sounds
Authors: Ohde Ralph N. , Sharf Donald J.
Published: October 2005

Although a primary acoustic property differentiating /w/ and /r/ is the onset frequency of the second formant transition (F2) relative to the onset of the third formant transition (F 3), it has been hypothesized that the rate of change of F2 may provide additional cues to this glide distinction. In order to investigate this supposition, transition rate of F2 was systematically varied while holding F2 onsets constant for stimuli modeled after child and adult vocal tracts. Eight subjects each participated in the child and adult conditions. The results showed that rate significantly affected the perception of /r/ and /w/ for only the adult condition. However, the results were generally opposite hypothetical predictions. That is, as transition rate increased, /w/ identification significantly decreased. These findings a re interpreted as supporting the perceptual salience of a slow transition rate for /w/, which is important in the glide-stop contrast in adult speech. Moreover, the results support the conclusion, that transition rate is not an important property in the differentiation of /r/ and /w/ relative to hypothetical predictions.
Japanese quail categorize /d/ across allophonic variation
Authors: Kluender Keith R. , Diehl Randy L. , Killeen Peter R.
Published: October 2005

Studies using animal subjects provide a unique opportunity to assess the nature of processes for perceiving speech. Demonstrations that animals have the ability to categorize speech sounds in ways similar to humans, serve to undermine claims that some levels of speech processing either are specific to humans or carry substantial cognitive requirements. In our study, Japanese quail were taught to discriminate natural CV + /s/ syllables beginning with /d/ from those beginning with /b/ or /g/. The phoneme /d/ was chosen because of its well-documented context-conditioned variability. Birds received food reinforcement for pecking a lighted key during repeated presentation of /d/ syllables, but were required to refrain from pecking in order for the presentation of /b/ and /g/ syllables to be terminated. The quail were first trained to discriminate /dæs/, /das/, /dus/, and /dis/ from tokens with the same vowels following /b/ and /g/. After reaching asymptotic performance for the /æ/, /a/, /u/, and /i/ contexts, birds were tested on novel tokens with the vowels /ε/, /Λ/, /v/, and /ɪ/. They received no reinforcement for pecking to novel tokens. Quail pecked substantially more to novel /d/ tokens than to novel /b/ or /g/ tokens, suggesting that they treated the novel stimuli as similar to their non-novel counterparts. Apparently, there exist significant acoustic/auditory commonalities among the class of /d/ allophones that may serve as the basis of category formation for both humans and animals. [Work supported by NICHD.]
Text to speech—An overview
Authors: Olive J. P. , Liberman M. Y.
Published: October 2005

We discuss the design of a text-to-speech synthesizer, which accepts any type of English text as input, and creates an appropriate speech signal as output. Effective algorithms for converting text to sound must make use of intermediate data structures that systematically encode the degrees of freedom available to speakers of the language being synthesized. These data structures are an engineering approximation to what linguists call phonological representations; we will call them “P-structures.” Any TTS system must: (1) define its version of P-structures; (2) design and implement algorithms for transforming input text into P-structures; (3) design and implement algorithms for transforming P-structures into sound. Task ♯1 is mainly a problem in applied linguistics; task ♯2 can best be seen as applied AI; task ♯3 is an application of phonetics and signal processing expertise. Because of the interdependence of approximate solutions in different portions of the system, integration of the various parts is a non-trivial problem. We will analyze an example of a TTS system, showing how these problems were handled in building and combining its numerous pieces. Finally, we point out some areas where better solutions are needed, and suggest how to find such solutions.
Aligning phonemes with the corresponding orthography in a word
Authors: Lawrence S. G. C. , Kaye G.
Published: October 2005

As part of a speech synthesis project a technique has been developed for aligning the phonemes in a phonemic transcription with the graphemes in a word. For example creationism /krɪeɪ∫ɪzəm/ can be aligned as c.r.e.a.t.ion.i.s.m with /k.r.ɪ.eɪ∫.n.ɪz.əm/. The technique has been used to determine in a machine-readable dictionary, where an entry is given with multiple orthographies and one pronunciation, whether the pronunciation may be used for all the orthographies. For example, in the Collins English Dictionary there appears the entry abutment /əbʌtmənt/ or abuttal. We know these two words are synonymous but are not pronounced the same. a.b.u.tt aligns with /ə.b.ʌ.t/ but the al cannot be aligned with /mənt/. The pronuciation of abutment cannot be used as the pronunciation of abuttal. The aligned forms of words and their pronunciations, together with statistics on frequency of rule use, is seen as an invaluable aid for developing a set of text-to-phoneme rules, where the ordering of rules, based on frequency of occurrence, is critical. It may also be useful as part of a pattern matching process in a speech recognition system. This paper will describe the algorithm and will give some results of using it against a phonemically tagged version of the Lancaster-Oslo/ Bergen Corpus.
Effects of listening to repeated syllables: Perstimulatory verbal transformations versus poststimulatory shifts in category boundaries
Authors: Warren Richard M. , Meyers M. D.
Published: October 2005

Listening to repeated syllables produces two quite different effects depending upon whether observations are made following or during repetition. Poststimulatory changes in category boundaries (for example, shifts in the voice-onset time boundary separation /tu/ from /du/ after hearing repetitions of either /tu/ or /du/) have been the subject of lively controversy concerning whether or not feature-detector adaptation (FDA) is responsible for such changes. Curiously, studies dealing with poststimulatory effects have not considered perstimulatory effects developing during stimulation. It is known that illusory changes (verbal transformations) occur while listening to repeated syllables, and the present study examined these verbal transformations for evidence of FDA. The repeated stimulus …/tu/, /du/, /tu/, /du/…, was used, since little or no net boundary change should be produced by FDA. The verbal transformation reported were inconsistent with adaptation theories. It is suggested that poststimulatory effects follow a “criterion shift rule” applying to perception in general, while verbal transformations tap special linquistic mechanisms employed normally to correct errors and enhance intelligibility of speech. [Work supported by NIH and NSF.]
Temporal variability in shallow-water acoustic transmission and its correlation with the environment
Authors: Ali Hassan B.
Published: October 2005

The ocean is a complex, highly variable medium of acoustic propagation. Medium-induced variability in the acoustic index of refraction (sound speed) can have significant effects on acoustic propagation. Using the results of SACLANTCEN measurements in two diverse geographical areas, the present paper discusses the correlation between the temporal variability of ocean parameters and the fluctuations in acoustic propagation. Following a discussion of the relevant spatial and temporal scales, brief comments are made on the theoretical approaches to propagation in a random medium. This is followed by a discussion of selected results of measurements in the Mediterranean and in the North Atlantic. It is shown that fluctuations in acoustic transmission loss closely correlate with ocean variability resulting from internal waves, tides, tidally advected changes in water masses, and ocean fine structure.