bluuebunny/crossref_metadata_2025 huggingface dataset:
On the use of energy in LPC-based recognition of isolated words
Authors: Brown M. K. , Rabiner L. R.
Published: October 2005

Recognition of isolated words by encoding speech into Linear Predictive Coefficients (LPC) is well known and widely accepted as one of the better methods for speech recognition. One of the drawbacks in relying entirely on LPC for recognition, however, is that the energy information in the speech is removed during the LPC analysis. This talk discusses problems involved in combining energy pattern information with the LPC pattern information and presents results of recognition experiments with one method. The method is general and applicable to the addition of any new feature to the recognition feature set. The energy information and LPC information are combined linearly in the frame-by-frame manner utilizing the dynamic time warping (DTW) method of Itakura. The Itakura distance function, which determines the spectral difference between two frames of speech, does not lend itself to direct statistical analysis in multiple dimensions. The method for obtaining the weighting for the linear combination involves an iterative minimization of a probability of error function. The combined energy and LPC distance function was tested using a 129-word “airline” vocabulary which was designed for speaker independent, isolated word recognition. The inclusion of energy information in the recognition feature space reduces recognition error rates by an average of about 3% as compared to LPC alone.
Speaker-independent discrete utterance recognition system, combining deterministic and probabalistic strategies
Authors: Vysotsky G.
Published: October 2005

A speaker-independent discrete utterance recognition system is described which represents utterances as sequences of segments. Each segment is labelled with one of four broad phonetic classes intended to be highly reliable over a large population of speakers. Each type of segment is parameterized by a set of acoustic features obtained from various combinations of the basic acoustic measurements provided by the front-end processor. Each sequence of segments together with its feature sets constitutes a test pattern. Each test pattern is compared with similarly constituted reference prototype patterns to obtain a recognition decision. Reference prototypes are stored in tables indexed by each possible sequence of segments. Stored in each table are means and standard deviations of segment features associated with each vocabulary word characterized by that sequence of segments. The system was evaluated using a 20-word vocabulary which includes the ten digits. A mean recognition accuracy of about 95% was obtained over a population of ten speakers, five of who participated in training the system. Over 90% of the errors were rejections rather than misidentifications.
Speaker independent isolated digit recognition using hidden Markov models
Authors: Levinson S. E. , Rabiner L. R. , Sondhi M. M.
Published: October 2005

A method for speaker independent isolated digit recognition based on modeling entire words as discrete probabilistic functions of a Markov process is described. Training is a three-part process comprising conventional methods of linear prediction analysis and vector quantization of the LPCs followed by an algorithm [L. E. Baum, Inequalities 3, 1–8 (1972)] for estimating the parameters of a hidden Markov process. Recognition utilizes linear prediction and vector quantization steps prior to maximum likelihood classification based on the Viterbi algorithm [A. J. Viterbi, IEEE Trans. Inf. Theo. IT-13, 260–269 (1967)]. After training based on a 1000-token set, recognition experiments were conducted on a separate 1000-token test set obtained from 100 new talkers. In this test a 3.5% error rate was observed which is comparable to that measured in an identical test of an LPC/DTW system [L. R. Rabiner et al., IEEE Trans. Acoust. Speech Signal Process. ASSP-37, 336–349 (1979)]. The computational demand for recognition under the new system is reduced by a factor of approximately ten in both time and memory compared to that of the LPC/DTW system. Issues of selection of model structures, averaging techniques to obtain model stability, and methods of compensating for finite training set size are also discussed.
Some experiments of a speaker-independent isolated word recognition using the Selective Weighted Matching
Authors: Mizuno K. , Iizuka H. , Yamada K.
Published: October 2005

At the last meeting in Chicago, we reported the speaker-independent isolated word recognition system using the Selective Weighted Matching. This paper refers to the results of some experiments to investigate the relation between recognition accuracy and following items: (1) the number of training talkers, (2) the number of reference patterns, and (3) the recognition accuracy for 100 test talkers. In these experiments, we used a vocabulary (digits and two command words in Japanese) uttered over a telephone line by 500 talkers. Concerning (1), we made recognition tests for 100 test talkers within 96 reference patterns. The number of training talkers was varied from 100 to 400. In the case of 100 talkers, the recognition accuracy was 96.96% for the training talkers and 93.37% for the test talkers. In the case of 400 talkers, the results were 95.37% and 94.17%, respectively. By increasing the training talkers, the recognition accuracy was inclined to decrease for the training talkers and to increase for the test talkers, and the difference between them was diminished. From the results of these experiments, we decided the practical conditions for our recognition system.
Tuning to the speaker: dynamic adaptation of statistical parameters in isolated letter recognition
Authors: Stern Richard M. , Lasry Moshe J.
Published: October 2005

The performance of a feature-based, speaker-independent recognition system can be improved by enabling the system to learn the acoustical characteristics of individual speakers. Even when features are designed to be speaker-independent, it is typically observed that for a given feature and pair of letters within-speaker variation can be less than between-speaker variation. For example, across all speakers a given feature may have an expected value of 5 for the letter M and 10 for N, but a certain speaker may produce average values of 9 for M and 14 for N. In such cases it is necessary to adjust statistical feature parameters to the individual speaker to obtain optimal recognition performance. This paper describes a dynamic adaptation procedure for updating expected feature values during recognition. The algorithm uses maximum a posteriori probability (MAP) estimation techniques to update the mean vectors of sets of measure values on a speaker-by-speaker basis. In updating these mean vectors, the algorithm makes use of the observations input thus far, the relative variability of the features' means within and across subjects, and the covariance of the mean vectors within and across the various letters or sets of letters. The use of tuning produced a dramatic decrease in error rates for certain speakers and letters. [Work supported by NSF.]
Identification of CV syllables by children and adults when task demands are varied
Authors: Elliott Lois L. , Clifton Lu Ann
Published: October 2005

We previously reported that normal children require higher intensities, than adults, to identify three CV syllables [bɑ,dɑ,gɑ] [Elliott et al., Percept. Psychophys. 30, 411–416 (1981)]. We replicated the previous experimental condition and, also, presented a 5-CV condition (the 3 CVs used previously plus 2 CVs located at the category boundaries). Intensity ranges for each 6-year-old and adult S assured performance that varied from less than 50% to better than 90% correct. Thus all Ss received approximately equal numbers of positively reinforced trials. Since responses were limited to “ba,” “da,” and “ga,” Ss could never be correct when responding to the two extra CVs of the 5-CV test condition. It was hypothesized that if 6-year-olds were less attentive to the task than adults, they would perform relatively more poorly on the 5-CV task than the 3-CV task, when compared to adults, because of the longer test run and because of the lower overall level of positive reinforcement. An ANOVA showed no differences in “identification thresholds” or slopes of the identification functions between the 3- and 5-CV conditions, for either children or adults. This provides additional support for the conclusion that the higher intensities required by normal children do not reflect lack of attention. [Supported, in part, by NSF.]
Perceptual test of the error severity model of the recovery process for articulatory disorders in children
Authors: Sharf Donald J. , Ohde Ralph N.
Published: October 2005

According to the error severity model of the recovery process from articulatory disorders, children progress from errors of omission to substitution to distortion before correct sound production. Inherent in this model is the assumption that the distorted phoneme is perceived as a unique sound category. Although categorical perception studies have shown within category perception, by far the most robust effects have been observed across categories. Consequently, categorical perception theory would provide only weak support for the above assumption. Since the perception of a distorted phoneme category is fundamental to the error severity model, this study tested the perceptual reality of the distorted /r/. In order to determine if subjects could categorize acoustic properties of /Cej/-type utterances varying in F2 and F3 onset frequencies as distorted /r/, speech pathologists identified two 25-stimuli manifolds synthesized so as to approximate /r/, /w/ and defective /r/ sounds modeled after child and adult vocal tracts. Subjects scaled the stimuli between /r/ and /w/ in one condition and labeled them as /r/, /w/, or distorted /r/ in another condition. The results showed that subjects consistently identified a distorted /r/ category for the adult manifold but not for the child manifold. These results cast some doubt that the distorted /r/ is a viable perceptual category for speakers who hold the greatest interest among speech pathologists—children. [Work supported in part by NINCDS.]
Speech perception in noise as a function of hearing status
Authors: Matthies M. L. , Bilger R. C. , Yuchtman M.
Published: October 2005

Speech-recognition scores were obtained for two recorded tests (SPIN and MRT) at signal-to-babble ratios ranging from + 7 to − 1 dB S/B for 90 subjects. These subjects were selected to meet criteria of age, audiometric configuration, and hearing-aid use which defined five subgroups of 18 subjects each (college age, normal hearing; adult, normal hearing; adult, high-frequency hearing loss; adult, successful hearing-aid use; adult, unsuccessful hearing-aid use.) To assess the effects of increasing babble level on speech recognition scores, one should first try to minimize the group differences. We attempted to equate the three hearing-impaired groups with the normal subjects in three ways, equating the groups for the mean at the optimal S/B, across all S/B's and by graphically shifting that data to the normal's S/B function. The graphical method did not preserve the shape of the S/B function but the adjusted means made it possible to look primarily at the noise effects. Conclusions based on the corrected data about the speech recognition performance of hearing-impaired subjects in noise are substantially different from those based on the uncorrected data. In the corrected data, there is little difference between the hearing-impaired and the normal-hearing groups on the MRT and the apparent affects of S/B on the SPIN scores arc substantially reduced. [Work supported under contract to NINCDS.]
The feasibility of deriving an articulation index based scheme for assessing residual auditory function in listeners with sensorineural hearing impairment
Authors: Pavlovich Chaslav V.
Published: October 2005

In the first experiment the AI theory was applied to audiograms of normal and sensorineural hearing impaired individuals in order to predict speech discrimination under various conditions. Good predictions were found for the normal and the lesser impaired subjects, but not for those with greater impairments. Also, poor correlation was obtained between the reduction in the AI for everyday speech and different subjective estimates of auditory handicap. In the second experiment it was investigated whether the AI predictions for presbyacusic individuals could be improved by making use of the frequency unspecific proficiency factor concept as suggested by Fletcher [J. Acoust. Soc. Am. 24, 490 (1952)] and Dugal et al. [in Acoustical Factors Affecting Hearing Aid Performance, edited by G. A. Studebaker and I. Hochberg, (University Park Press, Baltimore, 1978), Chap. 17]. The results indicate that the proficiency factor is not frequency independent. It assumes the value of 1 at those frequencies where hearing sensitivity is normal and it is substantially reduced for frequencies where hearing threshold is elevated.
Effects of mild hearing loss and age on speech recognition in noise
Authors: Dubno Judy R. , Dirks Donald D. , Morgan Donald E.
Published: October 2005

Previous investigations have established that, under identical test conditions, hearing-impaired listeners have more difficulty than normal-hearing listeners understanding speech in noise. Using an adaptive strategy, the effect of mild sensorineural hearing loss on speech recognition in babble was evaluated and the extent of the interaction of mild hearing loss with adult listeners' chronological age was examined. The signal-to-babble ratio required to achieve 50% recognition was measured for three speech materials presented at 56, 72, and 88 dB SPL; likewise, performance without babble was measured. Four sets of subjects (N = 18, each set) were tested: normal-hearing listeners <44 and >65 years of age, and hearing-impaired subjects <44 and >65 years. Subjects were selected so that age-group audiograms were closely matched. For results in babble, a consistent and statistically significant difference was demonstrated between the groups differentiated by age and by hearing loss, while only the latter effect was present in the absence of babble. Significant differences in articulation indices (AIs) between the two age groups were found for results in babble only, while no differences in AIs were seen between the two hearing loss groups under either listening condition. [Work supported by NINCDS.]
Horizontal and vertical covariance of surface reverberation
Authors: Wilson Gary R.
Published: October 2005

Lake surface reverberation was measured simultaneously on four horizontally separated and nine vertically separated staves in two linear arrays. The vertical array was found to maintain a significant level of coherence at much larger separations than the horizontal array. The normalized horizontal covariance was constant with time, while the normalized vertical covariance oscillated slowly with a period that depended on the separation of the vertical staves. The measurements were compared to a theoretical model of reverberation by D. Middleton. The model was implemented with a uniform planar distribution of surface scatterers and adequately predicted the horizontal spatial covariance and the time dependence of both the horizontal and vertical covariance. However the simple planar surface model was unable to model the vertical spatial covariance, indicating a need for a more detailed description of the surface.
Backscatter from the ocean surface at low frequency
Authors: Barger James E.
Published: October 2005

Backscatter strengths from the ocean surface were measured using a vertically directive, impulsive sound source having a 26-Hz bandwidth centered at a frequency of 52 Hz. The ocean surface was characterized by a 6.3-m swell having an 80-m wavelength, with 15-kt wind waves superposed. Backscatter strengths were measured as functions of the vertical grazing angle θ and of the horizontal angle ψ between the swell and the backscatter directions. The results are summarized by the expression for scattering strength, SS = −66.5 + 53 sin θ + 8.7 cos ψ. These values of scattering strength are somewhat larger than those reported by Brown and Saenger [M. V. Brown and R. A. Saenger, J. Acoust. Soc. Am. 52, 944–960 (1973)], but their data were not obtained from surfaces having such a large swell. The backscattered intensities have swell-induced amplitude modulation, suggesting that backscatter from wind waves is periodically shadowed by swell troughs. [Work supported by DARPA.]
Modeling the vertical directionality of ambient noise in a range dependent environment using the adiabatic invariant approximation method
Authors: Northrop John
Published: October 2005

The adiabatic invariant approximation (AIA) method of tracing sound rays in a range dependent environment was used in computing the vertical arrival angle of ambient noise at various frequencies and depths. Both surface- and bottom-reflection coefficients were incorporated in the model so that calculations could be performed out to any number of convergence zones. Noise from shipping and storms were treated as monopoles and dipoles, respectively. It is shown how the results can be used to choose the best operating depth for a vertical line array.
A linear regression model for the wavenumber-frequency spectrum of the turbulent boundary layer pressure fluctuations
Authors: Hwang Y. F.
Published: October 2005

The rationale of using a linear regression model for estimating the wavenumber-frequency spectrum of the turbulent boundary layer pressure fluctuations is presented. The contention is that the wavenumber-frequency spectra, normalized by the convected ridge value at the respective frequency, are the same for all frequencies if the wavenumber is expressed in terms of a nondimensional wavenumber. The nondimensional wavenumber is the streamwise wavenumber that is normalized by the convected wavenumber at the respective frequency. The normalized wavenumber spectrum is then approximately represented by a set of discrete spectral coefficients. The linear regression model relates the response of a measuring system to these discrete spectral coefficients. The spectral coefficients are determined by least-square minimization of a set of randomly collected response data.
Hybrid phase-shift/time-delay digital beamforming
Authors: Gabel Robert A. , Kurth Richard R.
Published: October 2005

Digital phase-shift beamforming of narrow-band signals from uniform colinear hydrophone arrays may be accomplished by computationally efficient algorithms which exploit the functional regularity of the required phase-shift operations. However, phase-shift beamforming is a valid approximation to delay-and-sum steering over only a limited bandwidth whose value depends on array aperture and steering angle. This paper describes a multiple-beam digital beamforming structure which is a phase-shift/time-delay hybrid and which an be designed for operating bandwidths in excess of the phase-shift limit. Much of the computational efficiency of colinear array phase-shift beamforming is retained in this approach, and it can offer substantial advantage over the alternative of delay steering by digital interpolation. This will be demonstrated by examples.
On the use of focused horizontal arrays as mode separation and source location devices in ocean acoustics
Authors: Lynch James F.
Published: October 2005

It is shown that one can perform mode separation and source location using a focused horizontal array by utilizing the fact that the system response is greatest to a source located at or near the focal point. This mode separation/source location scheme is discussed for four different physical situations: (1) a motionless point cw source in a range invariant environment, (2) a motionless point cw source in a range varying environment, (3) a motionless point broadband source in a range invariant environment, and (4) a moving cw source in a range invariant waveguide environment. Two types of (horizontal) arrays are treated, the line array and the circularly curved array.
A pseudorandom noise source, programmable in center frequency and bandwidth
Authors: Coulbourn Dixon W.
Published: October 2005

A source of pseudorandom (PR) noise with switch-selectable center frequency and bandwidth is discussed. PR noise is generated by shift register encoders. The noise is filtered at baseband before being heterodyned to form uncorrelated symmetric sidebands of a suppressed carrier. The carrier is generated by an accumulator frequency synthesizer employing a multiplier-accumulator chip. The chip makes possible use of various crystal frequencies and allows for a variety of frequency step sizes.
Optimizing the performance of a quantizer
Authors: Struzinski William A.
Published: October 2005

In a previous paper [W. A. Struzinski, J. Acoust. Soc. Am. Suppl. 1 70, S16 (1981)], a mathematical model was developed to compute the OR-ing loss for quantizers followed by an OR-ing device and an accumulator. The quantizer investigated was a three-bit device that extended from the noise-only mean m0 to m0 + 2σ. The subject paper examines different spans of the same three-bit quantizer. It is determined that the best performance results when the quantizer extends from the noise-only mean m0 to m0 + 3σ. The OR-ing loss and the input SNR requirements to the OR-ing device are computed for the m0 to m0 + 3σ quantizer. These results are compared to those of the m0 to m0 + 2σ quantizer. It is concluded that a quantizer spanning the range m0 to m0 + 3σ is most beneficial for small alarm probabilities, small number of samples in the accumulator, and higher number of channels OR-ed. [Work supported by the Naval Sea Systems Command.]
Complexity and contradiction in proscenium theater design—The last one hundred years
Authors: Izenour George C.
Published: October 2005

Proscenium theater design, rooted in Baroque tradition of court theater design and Beaux Arts architectural design achieved apogee in Opera de Paris (1875). Bayreuth Festpielhaus (1876) touched off a controversy in theater design among architecture, engineering, and artistic style that persists to this day. Opera de Paris was the last theater of historical importance where the architect alone made all crucial design decisions. Bayreuth Festpielhaus was the first theater of historical significance where the architect shared responsibility for design and technology with a theater consultant. At the time there was no such thing as an acoustical consultant. The ensuing century (1880–1980) changed everything. The industrial revolution changed structure and added mechanical and electrical engineering to the building process. Sabine provided the method for acoustical predesign of interior spaces. Post W.W. II computer revolution provided sophistication of operation. Mechanized transportation changed forever the relation of theater buildings to the overall fabric of urban design. These disparate disciplines have each contributed to the complexity of design and execution of theater buildings and the still unresolved artistic styles have all together become the modus operandi of contemporary theater design. It is for reasons both of a program dictating multiple use and the sheer magnitude of the engineering solutions resulting therefrom that apogee of proscenium theater design for our time will have been consumated in Teatro Teresa Carrena to be opened in Caracas, Venezuela (1983).
Acoustical modeling of Troy Music Hall
Authors: Ayyappan D. P.
Published: October 2005

An acoustical model built to a scale of 1:16 was utilized in evaluating the acoustics of the Troy Music Hall in Troy, New York. The model was modified into different configurations to identify the specific physical characteristics of the hall that might aid the acoustical qualities of the hall. Technical limits and usefulness of an acoustical model to determine the probable acoustical qualities of concert halls at an early stage were evaluated by comparing the objective qualities in the model and in its prototype. The initial assumption involves the accepted high quality of Troy Music Hall. It was found that an acoustical model is an effective research tool, within limitations, in probing the early energy components. The objective data obtained from the model studies coincide, in general, with the subjective qualities found in the hall. The model study shows that the first balcony in the Troy Music Hall receives an equal distribution of lateral and non-lateral energies in the first 80 ms.
Effective acoustic nonlinear parameter (B/A) of a mixture
Authors: Apfel Robert E. , Cobb Wesley N.
Published: October 2005

We derive an expression for the effective nonlinearity parameter, B/A, of a mixture for which the density, compressibility, B/A, and mass (volume) fraction of each component is known. We then compare the predictions with experimental results reported in the literature and with our own experimental results for compositions ranging from solutions to tissues. Finally, we attempt to rationalize differences between predictions and experimental results, where they exist. [Work supported by U.S. Office of Naval Research.]
Rapid cavitation in water induced by the reflection of shock waves
Authors: Unger Bruce T. , Marston Philip L.
Published: October 2005

Negative pressures were produced in distilled water by reflecting shock pulses of 11 MPa off a quasifree water-Mylar-air interface. The incident pulses, created by conventional impact techniques, were typically 1.7 μs in duration. An interferometer measured the displacement of the interface from which the velocity history of the Mylar could be extracted. Tension is created in the water when rarefaction waves collide. The tension results in cavitation which is evidenced by a rapid rebound of the Mylar's velocity. Difficulties experienced in previous experiments [P. L. Marston and G. L. Pullen, in Shock Waves in Condensed Matter, 1981, edited by W. J. Nellis et al. (AIP, New York, 1982), pp. 515–519] have been overcome by reducing the thickness of the Mylar which initially constrains the water. Velocity histories give a clear indication of cavitation in the sample; the abrupt tension being relieved by bubble formation within 1 μs. Also evident is reverberation within the spalled layer of the pressure wave radiated by the bubbles. The results suggest an apparent dynamic tensile strength ⩾5 MPa for moderately clean water. [Work supported by ONR and the American Chemical Society Petroleum Research Fund. Marston is an Alfred P. Sloan Research Fellow.]
Parametric acoustic array formation in dispersive fluids
Authors: Hamilton Mark F. , Fenlon Francis H.
Published: October 2005

The effect of dispersion on parametric array formation is investigated via solutions of the second-order paraxial wave equation for Gaussian source excitations. Only when |δ| > αT/k− does dispersion noticeably influence the nonlinear interaction, where δ = 1 − (k1 − k2)/k− is the dispersion parameter, kj (j = 1,2) and k− are primary-beam and difference-frequency wavenumbers (f1 − f2 = f−), respectively, and αT = α1 + α2 − α− is the combined attenuation coefficient. In contrast with one-dimensional dispersive wave interactions, the entire difference-frequency pressure field depends significantly on the sign of δ (δ > 0 if the sound speed increases with frequency). Axial pressure field curves [F. H. Fenlon and M. F. Hamilton, J. Acoust. Soc. Am. Suppl. 1 69, S81 (1981)], farfield directivity patterns, and three-dimensional field plots will be presented. For an absorption-limited array the directivity function reduces to [1 + i(2k−/αT)(sin2 θ/2 − δ/2)]−1. The maximum radiation is therefore shifted off axis to a direction determined by k1 − k2 = k− cos θ, which is the resonance condition for collimated plane-wave interactions. [Work supported by ONR.]
Parametric sonar as applied to high resolution boundary scattering measurement
Authors: Konrad William L. , Roderick William I. , Carlton Lynn F.
Published: October 2005

The use of the parametric acoustic source with its narrow beam and lack of sidelobes permits measurement of sea surface and bottom forward and back scatter to very low grazing angles. Measurements using conventional sources are often contaminated by sidelobe or other unwanted returns which result when unavoidably large boundary areas are illuminated. This paper describes the design and performance of one parametric source which has been employed for such measurements. [Work supported by NAVSEA and NORDA 530.]
Recovery of spatial tuning of auditory neurons in the owl's optic tectum
Authors: Leibovic Stephen J. , Knudsen Eric I.
Published: October 2005

Monaural occlusion alters binaural sound localization cues. Nevertheless, young barn owls learn to localize sounds after eight weeks of occlusion. We investigated effects of monaural occlusion on responses of space-tuned neurons in the optic tectum. In normal birds, 85% of cells in deep layers respond to sound and light (bimodal); the rest respond to sound only. None respond to light only. Bimodal cells have coincident auditory and visual receptive fields and space for both modalities is mapped onto the tectum. Acute ear plugging abolished the auditory responsiveness of tectal cells. In contrast, after 8 to 14 weeks of occlusion, tectal cells were responsive and space-tuned. Twenty recordings from superficial tectal layers revealed all normal receptive fields. In deeper layers (43 recordings), 50% of the cells were bimodal, 40% responded to light only and 10% to sound only. Although the auditory fields were elongated vertically, they were normal in their horizontal dimensions. Moreover, the auditory and visual fields of single neurons were horizontally aligned. The recovery of auditory spatial tuning and the alignment of auditory and visual fields indicates that the binaural stimulus requirements of these neurons changed in an adaptive manner in response to altered binaural input.
The external ears as receiving antennas in echolocating bats
Authors: Simmons J. A.
Published: October 2005

The external ears of bats appear to vary greatly in size and shape, but they in fact have dimensions specifically related to the structure of sonar sounds in different species. They determine the directionality of hearing and produce cues for vertical target localization. The pinna of broadband (FM) bats is equal in length to the wavelength of the lowest first-harmonic frequencies in the sonar signals, even if the bat only broadcasts higher-order harmonics into the air. The bladelike tragus focuses the directional sensitivity of hearing more sharply and cleanly to the front than the pinna alone can achieve. It also produces secondary reflections within the external ear which encode target elevation and which are necessary for accurate vertical localization of targets. Narrow-band (CF) bats have a pinna 5 to 8 times longer than the wavelength of predominant signal frequencies and have sharper directional sensitivity than broadband bats, which have a pinna only 3 to 4 times the predominant wavelengths. The configuration of the external ear matches the timing of tragus reflections to the period (autocorrelation) structure of FM sonar sounds to avoid average-phase ambiguity in perception of target elevation.
Beluga whale echolocation signals in two different ambient noise environments
Authors: Au Whitlow W. L. , Carder Donald A. , Penner Ralph H. , Scronce Billy L.
Published: October 2005

The echolocation signals of a Beluga whale (Delphinapterus lecus) were measured, first in San Siego Bay, and later in Kaneohe Bay, Oahu, Hawaii, while the animal was performing a target detection task. The ambient noise of both bays is dominated by snapping shrimp, with the noise level in Kaneohe Bay typically 20 dB greater than in San Diego Bay. In San Diego Bay, the animal emitted clicks with peak frequencies between 40 and 60 kHz, and bandwidths between 15 and 25 kHz. When the animal was moved to Kaneohe Bay, it used higher frequency clicks with peak frequencies between 100 and 120 kHz, and bandwidths between 20 and 40 kHz. The shift in the peak frequencies was probably caused by the difference in the ambient noise environment between the two sites, and may represent an attempt by the animal to optimize the signal-to-noise ratio during the target detection task. The whale also emitted signals with higher source levels and source energy flux densities in Kaneohe Bay than in San Diego Bay, even though the detection task in Kaneohe Bay was relatively simple and the task in San Diego Bay was relatively difficult.
Temporal resolution in normal-hearing and noise-exposed chinchillas
Authors: Giraudi-Perry Diane , Salvi Richard J. , Henderson Donald
Published: October 2005

Auditory temporal resolution has been shown to deteriorate with sensorineural hearing loss (Boothroyd, 1973; Fitzgibbons, 1979); however, there is considerable intersubject variability in human studies. The purpose of the present experiment was to investigate the effect of stimulus presentation level on the gap detection thresholds obtained from chinchillas during various amounts of noise-induced asymptotic threshold shift (ATS). ATS was induced with an octave-band of noise centered at 500 Hz and having a SPL of 75, 85, 95, and 100 dB. Gap detection thresholds were unaffected by the 75-dB SPL noise exposure. However, during the 85-dB SPL noise exposure, gap detection thresholds were longer than normal if compared at the same sound pressure levels, but within normal limits if compared at similiar sensation levels. At ATS for the 95 or 100-dB SPL noise exposures, gap detection thresholds were significantly wider than pre-exposure measures regardless of whether the comparison was in terms of sound pressure level or sensation level. The results show that there is an orderly breakdown in temporal resolution as the degree of noise-induced ATS increased. [Supported in part by grants from NIH (NS 1676), NIOSH (OH-00364), and the U.S. Army Medical Research and Development Command (DAMD 17-80-0133)].
No hysteresis effect in adaptive masked thresholds
Authors: Weber Daniel L. , Habler Betty L.
Published: October 2005

We measured forward-masked thresholds for a 10-ms, 1-kHz sinusoidal signal as a function of masker level for both sinusoidal and narrowband (60 Hz wide) noise maskers at five masker frequencies (0.6, 0.8, 1.0, 1.15, and 1.25 kHz). We measured these growth-of-forward-masking functions in the conventional fashion (determine the threshold level of the signal for a fixed level of the masker) and with the converse procedure (determine the masker level necessary to just mask a given signal). A common growth-of-masking function describes the results of both procedures for a given masker type and frequency, i.e., identical stimuli lead to identical performance regardless of whether one varies signal level or masker level. The growth-of-masking functions for different masker frequencies show varying degrees of nonlinearity. The nonlinearity of the growth-of-masking functions underlies the discrepancies which arise between masking pattern and tuning curve data. These discrepancies do not arise because of a “hysteresis effect” between the psychophysical procedures. [Research support by NIH and NSF.]
A quantal first effect of pitch shift?
Authors: Burns Edward M.
Published: October 2005

Langer [Exp. Brain Res. 44, 450–454 (1981)] has proposed a model for the perception of the “periodicity pitch” of AM tones based on the neuronal cross correlation of subharmonics of the carrier frequency with an internal oscillator with a period of 0.4 ms which is phase locked to the modulation envelope. The evidence for the 0.4-ms-period internal oscillator comes from two sources: (1) physiological measurements on single neurons from the midbrain of the Guinea fowl, and (2) psychophysical measurements on the pitch perception of AM tones by humans. The pitch experiment is a version of the classic “first effect of pitch shift” experiments wherein observers match the pitch of an AM tone whose carrier frequency is shifted, in constant (Hz) increments, over a range corresponding to about twice the modulation frequency. The primary difference between Langner's experiment and previous experiments is in the resolution of carrier shifts (increments of 10 Hz). Langner reports that, in contrast to the smooth shift in pitch estimates obtained in previous studies, many observers show steplike shifts, with the step size corresponding to a change in the period of the pitch estimate of about 0.4 ms. In an effort to replicate this result, we have obtained similar measurements on a large number of highly-trained observers. To date we have found no evidence of quantal shifts in pitch of the type described by Langner.
Peristyle—50 years
Authors: Harris D. A.
Published: October 2005

“A modern form of Greek Theater” is what Time magazine called it in January, 1933. The “Peristyle” concert hall, in Toledo, Ohio, formally opened to Leopold Stokowski conducting the Philadelphia Symphony Orchestra. Termed “a modern version of an open air theater,” semi-circular tiers surround the orchestra section with the topmost row topped by ionic colonades. A generous stage, cork flooring, marble paneled walls, and gently domed ceiling that extends beyond the colonades complete the acoustical envelope. A concealed lighting system gives an effect from “bright warm sunlight” to “a night sky shimmering with moonlight.” Opening to harsh criticisms of both the architecture and acoustics, the Peristyle, a part of the Toledo Museum of Art and a gift of Edward Drummond Libby, is generally considered to be an excellent hall for listeners. Musicians are not universally in agreement. A gentle blending of the orchestra can be found at nearly every seat. Yet the players complain of not being able to hear each other. To this day, electronic amplification is unnecessary even for verbal announcements. With only slight modifications over decades, the Peristyle acoustical attributes will be described using modern day technology and equipment with the hall in its present state.
Integration of melody and text in memory for songs
Authors: Serafine Mary Louise , Crowder Robert G. , Repp Bruno H.
Published: October 2005

Subjects with varying musical experience listened to a series of 24 brief excerpts from relatively unfamiliar folksongs. Subsequently, test series of 20 similar excerpts was presented and the subjects indicated for each excerpt whether they had heard that precise song before or, if not, whether they had heard the tune or the words. The test items included (a) old songs, (b) new songs, (c) old tunes with new words, (d) new tunes with old words, and (e) old tunes with “mismatched” old words that had previously been part of a different song. The results showed that old songs were recognized very well, whereas recognition of old tunes with new or mismatched old words was very poor, and recognition of old words with new or mismatched old tunes was good but nevertheless below the accuracy achieved for old songs. Thus, melody and text of songs seem to be remembered in an integral fashion, not as separate entities. [Work supported by NSF.]
Danish activities concerning noise in the environment
Authors: Ingerslev Fritz
Published: October 2005

The paper describes the administrative activities and the distribution between federal and local authorities. The importance of having a federal agency with highly qualified employees who can establish a superior national noise abatement strategy is stressed. The federal authority should represent the country in international collaboration. It is claimed that noise abatement will be diffuse and weak, if it is not based on a national strategy. The discussion of noise in the environment covers: external industrial noise, road traffic noise, and air traffic noise. The principles on which the maximum permissible Danish noise exposure levels are based will be explained. ISO 1996, 1st edition 1971, has played a decisive part. The maximum permissible Danish noise exposure levels for external industrial noise are strict and enforced for new plants and in connection with enlargement of existing plants. The regulations concerning road traffic noise are based on results of extensive interviews of persons living in areas with various exposure levels. The results of these interviews will be reported as well as the conclusions drawn.
Noise levels of Hong Kong marine craft
Authors: Burke Richard E.
Published: October 2005

Noise measurements were made of jetfoils, hydrofoils, hovercraft, and nine other kinds of passenger and commercial marine craft operating in Hong Kong's Victoria Harbor for the purpose of predicting noise impacts expected from similar craft at a proposed offshore airport. Tape recordings of several passbys of each craft were analyzed to obtain characteristic time histories, spectra, and maximum, statistical, and equivalent noise levels. Results provide initial indication of main concerns expected from marine craft noise and suggest operational abatement measures which may be effective. [Work supported by the Hong Kong Civil Aviation Department.]
Metabolic requirements endocochlear potential (EP)
Authors: Kobayashi T. , Rokugo M. , Thalmann I. , Thalmann R.
Published: October 2005

We have, in recent years, developed a method for arterial perfusion of the isolated inner ear of the guinea pig with “artificial blood,” consisting of an emulsion of a perfluorocarbon oxygen carrier in a physiological salt solution, containing a high molecular weight polyol as emulsifier and plasma expander. Using this technique, we found that, in addition to D-glucose, mannose can sustain the EP at normal levels for prolonged periods, while L-glucose, fructose, and galactose are ineffective. We also demonstrated that lactate and pyruvate can support the potential [Kambayashi et al., Hear. Res. 7, 105–114 (1982)]. In subsequent studies using the same technique, we have found that acetate, acetoacetate, and betahydroxybutyrate can also maintain the EP at normal levels; however, glycerol and phosphoenolpyruvate, as well as respresentative amino acids such as glutamine, glutamate, and alanine could not support the EP. Experiments concerning the possible utilization of fatty acids by the stria vascularis are still inconclusive since the synthetic blood may lack adequate carriers for these substances. A different perfusion medium containing carrier proteins will be required for a definitive answer. [Supported by NIH.]
Alteration of furosemide ototoxicity
Authors: Rybak Leonard P. , Whitworth Craig
Published: October 2005

The present study was designed to investigate the effects of inhibitors of organic acid transport on furosemide ototoxicity. Chinchillas weighing 400–600 g were anesthetized with ketamine 45 mg/kg IM followed by pentobarbitol 30 mg/kg IM. Control animals were injected intravenously with 0.5 ml of either phosphate buffer or normal saline 30 min prior to injecting furosemide 25 mg/kg IV. Experimental animals received an intravenous injection of either probenecid 50 mg/kg in phosphate buffer or novobiocin 50 mg/kg in saline 30 min prior to the injection of furosemide 25 mg/kg IV. The magnitude of change of EP did not differ in the experimental group pretreated with novobiocin prior to furosemide compared with controls. However, the experimental group which received probenecid prior to furosemide showed a striking reduction in the magnitude of EP change compared to both controls and the novobiocin treated experimental group. The time required for EP recovery did not significantly differ in the three groups although the group treated with probenecid did show a tendency for longer recovery times. [Work supported by NIH and Deafness and Research Foundation.]
Model calculations of low-frequency intracochlear pressures and the cochlear input impedance of the cat and guinea pig
Authors: Koshigoe Shozo , Kwok Wai-Kwong , Tubis Arnold
Published: October 2005

Recent low-frequency measurements of intracochlear pressures and the cochlear input impedance of the cat [V. Nedzelnitsky, J. Acoust. Soc. Am. 68, 1676–1689 (1980); T. J. Lynch, III, V. Nedzelnitsky, and W. T. Peake, J. Acoust. Soc. Am. 72, 108–130 (1982)] and the guinea pig (A. Dancer and R. Franke, Hear. Res. 2, 192–205 (1980)] are shown to be in reasonable agreement with the results of cochlear model calculations. Included in the cochlear model are perilymph viscosity, the measured variation of the area of the scala vestibuli with distance from the stapes [P. Dallos, J. Acoust. Soc. Am. 48, 489–499 (1970)], and the finite impedance of the round window membrane. Approximate analytic expressions for the fluid pressures in the scalae are derived so as to explicitly exhibit the dependence of the model results on cochlear parameters. [This work was supported by NSF.]
A nonlinear feedback model for the mechanical response of outer-hair-cell sterocilia
Authors: Koshigoe Shozo , Kwok Wai-Kwong , Tubis Arnold
Published: October 2005

There is some experimental evidence that the mechanical cochlear function is strongly influenced by the efferent innervation of outer-hair-cell stereocilia (OHCS). [See, e.g., D. C. Mountain, Science 210, 71–72 (1980); J. H. Siegel and D. O. Kim, Hear. Res. 6, 171–182 (1982).] This suggests that the various nonlinear and active mechanical features of the cochlear response may be mainly rooted in the OHCS. We propose a specific nonlinear feedback model for the mechanics of the OHCS, which is a generalization of a linear model proposed by Mountain. It gives formally the combination of negative resistance and nonlinear damping used in previous calculations [S. Koshigoe and A. Tubis, J. Acoust. Soc. Am. Suppl. 1 71, S17 (1982)]. The parameters of the model are determined so as to account for experimental measurements of the basilar membrane response as well as stimulated and spontaneous emissions in the ear canal. [This work was supported by NSF.]
How important is syntactic resolution of orthographic ambiguity?
Authors: Fisher William M.
Published: October 2005

Low-cost English text-to-speech systems typically do not use syntactic analysis. As a result, they must sometimes mispronounce certain words whose correct pronunciation depends on their surface syntactic category, such as “use.” Using the grammatically tagged Brown Corpus as a model of English text, I estimated how much knowing the part-of-speech of words can help text-to-speech systems: the difference between the minimum phonemic error rate achievable with and without such syntactic knowledge is 0.015% counting only segmental errors, or 0.025% if stress errors are also counted. Six types of ambiguity were found: consonant voicing (“use”); location of primary stress (“present”); degree of secondary stress, with associated vowel reduction (“separate”); vowel syncope (“ragged”); “French final e” (“expose”); and vowel quality (“live”). Details of the calculations and lists of the words found to have these ambiguities will be presented.
Noise, land use planning and the HUD noise policy
Authors: Brown Richard H.
Published: October 2005

As opportunities for additional significant reductions in major noise sources decrease, land use planning remains one of the few ways to prevent noise problems from developing. The HUD noise policy specifically encourages communities to consider noise in their land use planning. It is not, however, the total answer by any means. There will always be situations where other local priorities must take precedence, particularly in urban areas. Noise attenuation measures will continue to be important and a crucial part of the HUD noise policy. Lacking any specific legislative authority on general land use issues, the Federal role can only be to encourage local governments to consider noise in their land use planning process and to provide information.