bluuebunny/crossref_metadata_2025 huggingface dataset:
An approach to the theoretical background of statistical energy analysis applied to structural vibration
Authors: Woodhouse J.
Published: October 2005

Rayleigh’s classical approach to the study of vibration of systems having a finite number of degrees of freedom is applied to the problem of coupling of subsystems in a complicated structure, in order to probe the regions of applicability of the approach to vibration analysis usually known as statistical energy analysis (SEA). The classical method has advantages of simplicity and rigor over previous approaches to the background of SEA in certain cases, and provides extensions and simplifications in several areas of the theory. It also suggests modifications to SEA modeling strategy depending on the type of coupling involved, even when that coupling is weak, so that earlier analyses might be thought to apply.
Acoustic transmission matrix of a variable area duct or nozzle carrying a compressible subsonic flow
Authors: Miles J. H.
Published: October 2005

The differential equations governing the propagation of sound in a variable area duct or nozzle carrying a one-dimensional subsonic compressible fluid flow are derived and put in state variable form using acoustic pressure and particle velocity as the state variables. The duct or nozzle is divided into a number of regions. The region size is selected so that in each region the Mach number can be assumed constant and the area variation can be approximated by an exponential area variation. Consequently, the state variable equation in each region has constant coefficients. The transmission matrix for each region is obtained by solving the constant coefficient acoustic state variable differential equation. The transmission matrix for the duct or nozzle is the product of the individual transmission matrices of each region. Solutions are presented for several geometries with and without mean flow.
Sound levels around buildings in suburbia
Authors: Quirt J. D.
Published: October 2005

This paper presents the results of preliminary measurements of the difference between the incident sound levels at the front and rear facades of suburban detached and semi-detached houses adjacent to major roadways. The measurements also yielded data on sound transmission through open windows and comparisons between the sound levels measured in open windows, at the surface of the building facade, and at 2 m from the facade.
Modeling reverse middle ear transmission: Aural acoustic distortion products, “echoes,” and spontaneous emissions
Authors: Matthews J. W. , Kim D. O. , Molnar C. E. , Neely S. T.
Published: October 2005

Since 1978, when Kemp reported the existence of stimulated acoustic emissions from within the human auditory system [J. Acoust. Soc. Am. 64, 1386–1391], several studies have indicated that acoustic signals originating within the cochlea propagate through the middle ear into the ear canal. We have used nonlinear cochlear mechanical models to interpret distortion products observed both in the acoustic signal in the ear canal and in the response patterns of single cochlear nerve fibers. In addition to a nonlinear cochlear model, our modeling system includes a bidirectional middle ear model and an acoustic coupler model; these additional elements are needed in order to make quantitative comparisons between model results and the experimental observations, The mechanical middle ear model we have developed is based on experiments measuring the forward transmission characteristics of the auditory systems of cats [e.g., Guinan and Peake, J. Acoust. Soc. Am. 41, 1237–1261 (1967)], and is adequate for frequencies below 3 kHz. In order to extend the model to higher frequencies a more elaborate representation of the motion of the eardrum will have to be included. Our model results give indirect support for the adequacy of our middle ear model with respect to reverse transmission, but direct experimental measurements of reverse transmission properties of the middle ear are needed. [Supported by NIH grants NS07498, RR00396, NS00162, GM01827.]
A further study of the space and time stability of a narrow-band acoustic signal in the ocean: Intermediate range results
Authors: Herstein P. D. , Koenigs P. D. , Browning D. G.
Published: October 2005

The initial analysis of a narrow-band signal was conducted for a source-receiver distance of 1000 km [D. G. Browning, J. Acoust. Soc. Am 68 (S1), S72(A) 1980]. Although the bandwidth remained relatively narrow (∼3 mHz) it appeared there were distinct frequency components that could be associated with separate ray groups. In order to verify this, a similar analysis has been conducted at an intermediate range (125 km) where preliminary results indicate that the components may be resolvable. Space and time variability are given for percentage Doppler shift, bandwidth and intensity. The results are compared to predictions obtained from the FACT Option of the Generic Sonar Model. [Work supported by DARPA].
Temporal discrimination of tone burst pairs with and without frequency transitions
Authors: Divenyi Pierre L. , Robertson Lynn C.
Published: October 2005

Trained listeners were asked to discriminate, in a four-level 2AFC paradigm, the interval separating two tone burst markers. The total duration of the first marker was 10 ms (2-ms rise and fall times), whereas that of the second marker was 100 ms (with a 2-ms rise and a 10-ms fall time). The duration of a gap just discriminable from a nominally 0-ms gap was about 1 ms when the frequency of the two markers was identical (1 kHz). On the other hand, thresholds wet about ½ to 1½ orders of magnitude higher when the two frequencies differed by 2 octaves (2000 and 500 Hz, respectively). These data confirm earlier results. [Divenyi and Sachs, Percept. Psychophys. 24, 429–436 (1978)]. In the remaining conditions the first marker was a 10-ms tone burst of 2 kHz, while the second marker was a 100-ms tone burst starting with a frequency sweep toward a terminal frequency. This sweep either started at 2 kHz and ended 2 octaves lower at 500 Hz (i.e., the sweep moved away from the frequency of the first marker) or vice versa (i.e., the sweep moved toward the frequency of the first marker). Several sweep durations (10, 30, 50, and 100 ms) were used. Gap discrimination thresholds were found to be in the 1-ms range regardless of the direction of the frequency sweep in the second marker as long as the duration of the frequency transition was no longer than 30 ms. The threshold remained similarly low for the longer sweep durations whenever the frequency of the second marker started at that of the first and then moved away from it. On the other hand, gap thresholds became higher in those conditions in which the duration of the transition was 50 ms or longer, and the frequency of the second marker moved toward that of the first but started at a frequency 2 octaves below. The results appear to bear relevance to the time window of auditory analysis, on the one hand, and to the perception of CV formant transitions, on the other. [Work supported by NINCDS and the Veterans Administration.]
Word constraints on syllable identification
Authors: Massone María Ignacia , de Manrique Ann María B.
Published: October 2005

In a previous work [Ana M. B. de Manrique and María I. Massone, submitted to J. Acoust. Soc. Am. (19791] a vowel effect on the identification of voiceless Spanish fricatives [f, s, ∫] in transitionless syllables was observed. The present experiment was conducted to determine whether the lexical-semantic value of words neutralized the vowel effect just described. The test material consisted of two sets of six words each recorded by a male Spanish-speaker. The initial syllables which were one of the following: [so, su, fi, fe, ∫o, ∫u;], were gated out and replaced by the transitionless syllables previously mentioned by tape-splicing technique. Words in the first set allowed two alternatives: e.g. “suma” [suma] ‘he sums’/ “fuma” [fuma] ‘he smokes,’ words in the second set allowed no choice: e.g., “lluvia” [∫uβia] ‘rain.’ The results showed that the vowel effect is apparent when the phonetic percept evoked by this effect follows a lexical possibility, while it disappears when the phonetic percept competes with word identification. These data gives evidence of the level interaction in the speech perception process.
Scattering coefficients and Doppler spectra of specularly scattered sound from the sea surface
Authors: Roderick W. I. , Kanabis W. G.
Published: October 2005

A sea surface scattering experiment has been conducted in shallow water. A narrow beam parametric array, operating over the frequency range 10–30 kHz, projected acoustic energy at a 10° grazing angle to the surface. The reflected and scattered signals were received in the specular direction. Both the source and receiving hydrophone were mounted to underwater towers. Simultaneous with the scattering experiment, the time-varying wave height of the sea surface was measured by an acoustic technique. Scattering coefficients and Doppler spectra were computed from the scattered quadrature components. Likewise, processing of the wave-height data yielded rms wave heights and wave spectra. For the measurements, the Rayleigh roughness parameter varied between 4 and 100. The Doppler spectra were Gaussian with bandwidths related to the roughness parameter, and the scattering coefficients ranged from −2 to −10 dB. Familiar physical optic methods were used to model the acoustic data and the Pierson-Moskowitz spectrum modeled the sea surface data. [Work supported by NAVSEA and NUSC Independent Research Program.]
A confined parametric source
Authors: Leung P. M. , Berktay H. O.
Published: October 2005

A parametric source confined within a fluid-filled tube is proposed for use in a study of the properties of sea ice and to measure the ice thickness and the depth of water below the ice layer. This paper presents some experimental results obtained with a parametric array formed within a tube with pressure-release boundaries; the array being truncated, effectively, at the radiating end of the tube by the use of an acoustic low-pass filter. Two tubes of diameters 15 and 20 cm were used for the experimental study. The results are compared with those obtained for a truncated parametric array of the same length, but not confined laterally. [This work is supported by the Canadian Hydrographic Service, Central Region of the Department of Fisheries and Oceans and the Department of Supply and Services.]
Scattering and diffraction of acoustic waves by partially compliant cylinders
Authors: Benthien George , Gonzalez Manuel
Published: October 2005

The acoustic field that results from diffraction by an infinite cylinder which is rigid with the exception of two compliant strips parallel to the axis of the cylinder is very complex. In addition to the normal mechanisms for diffraction around a curved surface there is also edge diffraction by the compliant-hard interfaces. In this paper the diffraction by a partially compliant cylinder is analyzed for both an incident plane wave and a line source on the surface of the cylinder. The integral equation which describes the diffracted field is converted to a system of algebraic equations and solved numerically. The compliant strips are described by a surface impedance which is obtained from a layered medium model. A comparison of the numerical results with those obtained using geometrical theory of diffraction “GTD” methods is also presented.
Average excess attenuation during sound propagation from an isotropic source above grassland
Authors: Soom Andres , Gu Ron-ren
Published: October 2005

Measurements of sound attenuation from an isotropic source have been made over a meadow at propagation ranges between 15 and 300 m and for source and receiver heights within 3 m of the ground. Approximately 800 measurements were made at more than 70 source-receiver geometries under essentially constant ground conditions. The sound source was driven by a pseudo-random signal giving a discrete spectrum in the 100 to 2500 Hz frequency range. The received signal was analyzed and averaged in narrow bands of 3 Hz. The effects of propagation range, source height, receiver height, and vector wind in determining excess attenuation are presented in detail. The surface used in the tests appears to have a boundary impedance different from grasslands studied by previous investigators. It is also evident from the data that the theory of a simple source radiating into a quiescent, isothermal medium above an impedance plane often cannot be used to accurately predict average attenuation to distances much beyond 50 m from the source. Finally, it is shown that the method of averaging propagation data can significantly alter the apparent results. [Work supported by NSF.]
Free plate tuning and a range of different woods in 10 viola backs
Authors: Hutchins Carleen M.
Published: October 2005

Ten 16-in. violas each with a different back wood—but with other features maintained as constant as possible—have been constructed according to our plate tuning theories based on the frequency relationships of modes ♯2 and ♯5 in each pair of top and back free plates before assembly. These mode frequency relationships will be discussed and the instruments demonstrated as far as time permits.
Thermodynamic corrections to the sound velocity in a bubbly medium
Authors: Floyd Edward R.
Published: October 2005

For sufficiently low frequencies so that the adiabatic assumption holds, the sound velocity in a bubbly medium consisting of an air—water froth has been described by Wood's equation [A. L. Anderson and L. D. Hampton, J. Acoust. Soc. Am. 67, 1865–1889 (1980)] where the adiabatic compressibilities and densities of the bubble (heretofore air) and water are weighted by their respective fractional volumes. For adiabatic volume changes, bubble compressibility is inversely proportional to the ratio of specific heats. Heretofore, the specific heats considered were those for air. But bubbles innately have two additional degrees of freedom due to the energies partitioned into surface tension and buoyancy. These two additional degrees of freedom are investigated and a corrected ratio of specific heats is developed for incorporation into Wood's equation. In all cases, this correction lowers the sound velocity in a bubbly medium. [Work supported by the Independent Research Program of the Naval Ocean Systems Center.]
A simple method for measuring the temporal characteristics of broadband ultrasonic pulses
Authors: Riley Ward A. , Love L. Alan , Griffith David W.
Published: October 2005

Several optical diffraction techniques have been proposed for studying the temporal characteristics of ultrasonic pulses propagating in water [B. D. Cook, J. Acoust. Soc. Am. 60, 95–99 (1976); W. A. Riley, ibid. 65, 82–85 (1979); W. A. Riley, ibid. 67, 1386–1388 (1980)]. While these techniques have the advantage of permitting measurements to be made without disturbing the field during the measurement process, they have found limited application due in part to the nonuniform nature of the frequency response over the range of interest. A simple modification of two of these techniques can result in a method having an essentially flat frequency response from 1–15 MHz. This approach was used to study the temporal characteristics of the acoustic fields transmitted by diagnostic medical ultrasound transducers having nominal center frequencies of 2.5, 5.0, and 10 MHz. Temporal peak acoustic intensities were limited to approximately 0.01 W/cm2 to avoid nonlinear effects which could occur within the transducer, the acoustic medium, and the optical diffraction pattern at higher intensities. Measurements were performed at three distances from the transducer face to determine the extent to which the temporal field characteristics vary with position in the ultrasonic field. Techniques are currently being explored to permit the observation of higher acoustic intensities so that the nonlinear effects occurring in the transducer and the acoustic medium can be accurately studied with this approach. [Work supported by NIGMS Grant 27755.]
Further investigation into the influence of preceding liquids on stop consonant perception
Authors: Mann Virginia A. , Madden Jim , Russell J. Michael , Liberman Alvin
Published: October 2005

A perceptual dependence of stop consonants on preceding liquids was previously demonstrated by excising the CV portions of natural tokens of /al da/ and /ar da/ and replacing them with synthetic stimuli from along a /da/-/ga/ continuum. [V. Mann, Percept. Psychophys. 28, 407–412 (1980)] Using these “hybrid disyllables” a “duplex percept” has been created by presenting the F3 formant transition of the CV portion to one ear and the remaining stimulus portion to the other ear. Thus the F3 transition is simultaneously perceived as supporting the /da/-/ga/ distinction, and as an isolated “chirp,” Listeners performed a discrimination task on these materials, attending to either the speech percepts or the chirps. Speech discrimination was a clear function of liquid context: Consistent with previous results, the category boundary along the /da/-/ga/ continuum shifted in favor of more “g” responses when stops followed /al/ than when they followed /ar/. Chirp discrimination, however, was not related to liquid context. Since the effect of the preceding liquid appears specific to “perceiving in the speech mode” an explanation cannot be couched in terms of some low-level auditory effect on perception of the F3 transition. Rather, a phonetic explanation of the effect of liquid context remains plausible. [Research supported by NICHD and BRS.]
Perception of anticipatory coarticulation effects in /stri, stru/ sequences
Authors: Martin James G. , Bunnell H. T.
Published: October 2005

These experiments assess the identity and temporal reach of anticipatory coarticulation effects in /stri, stru/ sequences which can influence perception. Spoken /stri, stru/ pairs were cross-spliced after /s/ and after /t/ so that any coarticulatory information preceding the crosspoint incorrectly predicted the remainder of the sequence. Results were that recognition time (RT) to final vowel targets /i/ or /u/ was slower in crossed compared to intact (as spoken) sequences. Differences in RT between crossed and intact sequences were much smaller when crossing after /s/ than after /t/. Further work examines the relative contributions of acoustic information throughout the /str/ region. These experiments and others reported earlier on vowel-to-vowel effects show that the perceptual effects of anticipatory coarticulation are not limited to information in adjacent segments. Theories may treat context effects from nonadjacent segments as unwanted or unaccounted-for variance, but there is little reason to believe listeners do so. [Work supported by NIH.]
Identification of [bdg] at moderate and high sound pressure levels
Authors: Dorman M. F. , Marton K. , Dobbins E.
Published: October 2005

In experiment I listeners were presented a two formant [bdg] continuum at 55, 70, and 90 dB SPL. In the 90-dB condition the [g] category was greatly enlarged at the expense of the [d] category. In experiment II exemplars of [bdg] synthesized with two and three formants, with and without a burst, were presented to listeners at 50 and 90 dB. At 90 dB a decrement in intelligibility was found only for stimuli synthesized without a burst. In experiment III, the stimuli were presented in monaural and dichotic modes and in a condition with F1 reduced in intensity. Dichotic presentation increased intelligibility slightly more than F1 reduction.
Measuring the ride comfort of automobile seats
Authors: Varterasian John H.
Published: October 2005

A ride number to measure the “ride comfort” of an automobile seat has been developed that could be used to numerically rank nearly all seats. In this research, ride comfort is regarded as the capability of the seat to isolate the occupant from annoying road vibrations. The results were obtained from a program where subjects rated a variety of different seats on a paired comparison basis. The ride number is a result of arranging the measured dynamic seat parameters in an empirical formula for the best correlation with the subjective ratings. The ride number agreed with 67% of the ratings; this compares with a 60% agreement for a commercial “ride meter” that is based on the International Standards Organization (ISO) comfort criterion for humans. When seats of a more similar design (bucket seats) were considered, the agreement with the ride number was 80%, while with the rider meter it was 65%. The ride number, being “tuned” particularly to automotive vibrations, has shown that, in general, seats need not be heavy to provide traditional ride comfort.
Predicting vehicle ride comfort
Authors: Griffin Michael J. , Parsons Kenneth C.
Published: October 2005

Laboratory experiments have shown that the discomfort caused by whole-body vibration is highly dependent on the frequency, direction and duration of the vibration, the occurrence of impulses, and on the locations of the points of contact of the body with vibrating surfaces. The acceptability of vibration in vehicles depends on situational factors which vary over time and between vehicles. It must be recognized that vibration acceptability depends on these factors in addition to vibration intensity. The relative vibration discomfort in different vehicles can more easily be measured and predicted. The results of a series of laboratory experiments are used to define a general vibration discomfort prediction procedure which can be applied to seated subjects experiencing complex (random and impulsive) vibration occurring in up to twelve axes (three translational and three rotational axes on the supporting seat surface: three translational axes on the seat-back, and three translational axes at the feet). It is shown how this procedure may be applied with time-series analysis methods to determine the principal frequency components, axes, and vibration interfaces responsible for discomfort. The procedure may also be used for the evaluation of the vibration isolation provided by seating and other changes in vehicle design.
Observation of violin string motion with optical sensors and acoustic excitation
Authors: Arnold Eric B. , Weinreich Gabriel
Published: October 2005

Optical sensors [C. E. Gough, Acustica 44, 113–123 (1980)] are practical nonperturbative detectors of string position at individual points. Acoustic excitation provides a driving force which also is nonperturbative [G. Weinreich and E. Arnold, J. Acoust. Soc. Am. Suppl. 1, 67, S84 (1980)]. This method provides sufficient information about the terminating impedances of the string that realistic models may be used. Data obtained suggest that the assumption of a rigid nut should not be accepted without careful consideration, and effects of flexible support at both ends of the string on normal modes and bowing response are considered. [Work supported by NSF.]
Compliance of violin tables under static load in relation to tone quality
Authors: Pickering Norman C.
Published: October 2005

The static deflection of violin tops was measured in several places with and without string tension and with and without sound-post. A close estimate of the internal structure of the instrument can be made, with particular reference to the strength of the bass bar and thickness of the top in critical areas. The effective stiffness of the back at the soundpost position can be calculated. Data for good and bad instruments will be shown with clear indication of plates which are too thick, too thin, or too irregular.
Nonlinear scattering of ultrasound by bubbles: Numerical and experimental investigations
Authors: Eatock Brian C.
Published: October 2005

The magnitude of the nonlinear effect in the scattering of ultrasound by nitrogen bubbles in water was studied for ultrasonic frequencies and amplitudes typical of those used in diagnostic medical instruments. The purpose of the study was to determine whether this effect would be useful for the detection of bubbles in blood and tissue, for application in decompression research. Numerical solutions of the modified Rayleigh equation, including the effects of acoustic, thermal, and viscous damping, and the dependence of the polytropic gas constant on frequency, were obtained. A system for the spectral analysis of single pulses of ultrasound, scattered by bubbles was developed, and used in experiments intended to complement the numerical investigations. For conditions typical of diagnostic ultrasound, it was shown that nonlinear scattering is significant (second harmonic greater than −40 dB with respect to the fundamental) only for the population of bubbles which are close to, or smaller than, the resonance size. The nonlinear effect in the scattering of ultrasound by bubbles would not facilitate the detection of bubbles in blood and tissue, with currently available technology.
Segment duration and the mora in Japanese
Authors: Beckman M. E.
Published: October 2005

Linguists have made various claims for the mora as a durational unit in Japanese. One of the strongest of these claims is that the mora has such a basic phonetic reality that, for example, vowel lengths are adjusted to compensate for the intrinsic durations of tautomoraic consonants [M. S. Han, Onsei no kenkyuu 10, 81–100 (1962)]. Examination of a preliminary corpus of utterances used in the development of synthesis rules for Japanese, however, did not reveal this tendency toward moraic isochrony. This discrepancy between our findings and previous claims has led us to examine segment durations in a larger set of utterances (including readings by several native speakers of a long narrative passage) in order to determine whether a tendency to equalize mora durations might become apparent after other factors influencing duration are accounted for.
An approach to a microprocessor-based voice output
Authors: Coker C. H. , Kahn D. , Umeda N.
Published: October 2005

We describe a simple procedure for generating speech messages by means of the combination of a Bell Digital Signal Processor chip (DSP) and a conventional microprocessor. The method combines prosody rules developed for an articulatory synthesizer with concatenation of phonetically-marked, stored representations of whole English words. A Motorola MC68000 microprocessor selects data, expands it from a very compressed form, and computes pitch and duration and some allophonic modifications at boundaries. The results are supplied to the DSP, which is programmed to operate as a formant synthesizer.
Recent attempts to predict individual differences in TTS and PTS
Authors: Humes Larry E.
Published: October 2005

From the outset, large individual differences in temporary threshold shift (TTS) and permanent threshold shift (PTS) have been apparent in the results of studies on the effects of noise on hearing. A hypothesis proffered almost fifty years ago suggested that the TTS resulting from a brief exposure to a moderately intense exposure stimulus might be a good predictor of the PTS incurred by that same individual following repeated exposures to more intense acoustic stimulation. In the ensuing fifty-year period, numerous investigations have attempted to establish this “simple” relationship between TTS and PTS. The end result of five decades of research in this area has been the realization that the relationship between TTS and PTS is not a simple one. One new approach to the quantification of TTS data, however, has produced a new index called the integrated temporary threshold shift (ITTS) which shows more promise as a predictor of PTS. In addition, much recent research has focused on using the results of non-TTS paradigms to predict individual differences in noise-induced TTS. These new developments and their implications for research and industry will be reviewed.
Temporary threshold shift to 8-h noise exposures in man and monkey
Authors: Nielsen Donald W. , Elliott Donald N. , Boisvert Peter , Hunter-Duvar Ivan
Published: October 2005

Few investigators have studied the appropriateness of an animal model for the effects of noise on hearing in the human. The goal of our research is to provide such data for the squirrel monkey. Our approach was to reproduce industrial working conditions by using exposures of work-day length and recorded factory noises, in addition to octave-band and pink noises for both humans and monkeys. The results enable us to compare the effects of commonly used laboratory noises with those of recorded factory noises on man and monkey. We exposed 20 humans and 12 squirrel monkeys twice to each of five different noises (pink noise, two octave bands centered at 500 Hz and 4 kHz, stamping plant noise, and stall wrench noise) for 8 h at each of two levels. Auditory thresholds were determined after 1, 2, 4, and 8 h of noise exposure. TTS growth to each noise demonstrates that the squirrel monkey is similar to the human in the manner in which auditory thresholds shift as a function of time for these various noises. Presumably, the physiological changes underlying TTS are also similar for the two species. [Work supported by NIOSH.]
Concert shell design: A break with tradition
Authors: Kirkegaard R. Lawrence
Published: October 2005

While we all know that the shell is a critical element in the equipment of a multi-use hall, we also know that while trying to fulfill the dual role of serving both performer and audience the shell is often caught in a tug-of-war conflict unable to serve both roles at the same time. Balance, blend, projection, retention, intercommunication, differential support, appearance, economy, storage, erection, striking, etc., all are concerns the designer must address. In designing the shell for the newly completed Tennessee State Cultural Center in Nashville, we established a hierarchy of responsibilities for the various shell elements and then developed unique design features that enable the shell to serve its multiple roles with alacrity. The paper will discuss the design process involving theater consultant, shell manufacturer, architect, and users, and will illustrate the hierarchy of responsibilities for the various shell elements.
Subjective effects of variable delay and speech loss in dynamically managed voice systems
Authors: Gruber John G. , Strawczynski Leo
Published: October 2005

In this presentation we focus on speech impairments likely to arise in Dynamically Managed Voice Systems (DMVS). Here a DMVS is considered to be a system which may among other things use speech activity detection to exploit speech idle time and manage the resulting talkspurt traffic on a delay and on a loss basis. Examples of such systems include packet voice networks, buffered speech interpolators and advanced integrated services systems. Various speech quality classifications and test criteria used to evaluate the performance of speech systems are reviewed. Emphasis is placed on customer opinion of quality as defined by a rating scale, the objective being to provide the basis for exercising cost-performance tradeoffs. Based on recent subjective tests grade-of-service information is presented pertaining mainly to variable talkspurt delay and to various speech loss mechanisms including front-end and mid-talkspurt clipping. The importance of fixed delay in conjunction with echo, echo control and speech detection is also emphasized. Where possible comparisons with previous results are made.
Area noise monitor measurement to predict newspaper pressroom employee exposure
Authors: Hanson William J. , Hampel Gary A.
Published: October 2005

The information obtained in this study would be most helpful in designing a newspaper pressroom and should benefit those with existing pressrooms wishing to avoid costly engineering controls. This may be accomplished by properly locating operating consoles, work stations, and product conveyor access areas. The intent is simply to minimize employee penetration time in the relatively high noise risk areas. Pressroom noise was monitored for more than 600 hours to establish production trends. Dosimeters were employed to determine personnel exposure patterns for various locations, specific jobs, production rates, and types of product. An area monitor was used to obtain a time history and develop a correlation with audio dosimeter measurements. From this data we hope to develop a universal measurement procedure which will allow one to predict employee noise exposure from area monitor measurements. Press-room material absorption characteristics were determined from reverberation time and sound propagation from loss due to distance measurements. These parameters may be incorporated in the proposed measurement procedure. Specific dominant noise sources were verified with contour plotting, which also provided information on personnel exposure—position patterns. This was particularly applicable where employees' jobs required fairly regular patterns, allowing one to assess noise level zones most frequently encountered.
Temporal characteristics of the laryngeal devoicing gesture for voiceless consonants and fricative-stop clusters: Influences of vowel environment and speaker age
Authors: Weismer Gary
Published: October 2005

We have argued previously [G. Weismer, J. Phonetics 8, 427–438 (1980)] that the duration of the voiceless interval is essentially identical for prestressed, voiceless stops and fricatives. Moreover, small but systematic vowel influences on the duration of the voiceless interval also appear to be independent of manner of articulation, as evidenced by comparison of relevant fricative [M. F. Schwartz, J. Acoust. Soc. Am. 46, 480–481 (1969); G. Weismer and M. Elbert, J. Acoust. Soc. Am. Suppl. 1 67, S39 (1980)] and stop [G. Weismer, J. Phonetics 7, 197–204 (1979); R. Port and R. Rotunno, J. Acoust. Soc. Am. 66, 654–662 (1979)] data. In the present study, we describe voiceless interval durations associated with singleton stops and fricatives, as well as fricative-stop clusters, produced by young adults and preschool children. Results verify the above inferences drawn from the literature, and also reveal longer voiceless intervals in clusters as well as exaggerated vowel effects in children.
Mode disappearance in upslope propagation in variable depth shallow water above a fluid bottom
Authors: Pierce Allan D.
Published: October 2005

Recent work of Jensen and Kuperman [J. Acoust. Soc. Am. 67, 1564–1566 (1980)] suggest a failure of the adiabatic mode theory for upslope propagation near the critical depth Hc at which phase velocity equals sound speed in underlying fluid bottom. Present paper explores this possibility with a parametric solution [A.D. Pierce, J. Acoust. Soc. Am. 39, 1130–1141 (1966)] that relates bottom depth H(r), fraction of energy in water layer, acoustic pressure at bottom interface, and phase velocity, through a single parameter μ. Near the critical range rc (where H = Hc), the pressure amplitude in upper layer goes to zero as {rc − r)1/2 and bulk of energy is in bottom. The adiabatic mode theory applies as long as rc − r is larger or comparable to Hc and gives results similar to those computed with parabolic equation method. However, rate of transfer from water to bottom becomes very large as rc is approached and negates the adiabatic hypothesis. Proposed method of extending the model to circumvent this limitation results from an approximate substitution into a variational principle and yields equations coupling modal profile in water layer to propagating waves in bottom.
Rational linear approximation to the wave equation with bottom interaction
Authors: Greene Robert R.
Published: October 2005

A rational linear approximation is used to derive a range-dependent full-wave propagation model, much like the parabolic equation, which can handle the dual problem of high angle propagation and bottom interaction. It uses an inexpensive tridiagonal implicit range step for economical calculation in the presence of large gradients, where range steps are necessarily very short. The use of matched cubic splines gives an accurate treatment of reflection and refraction at density and sound-speed discontinuities. It gives an accurate treatment of propagation from 0° to 45° grazing angle. [Work supported by ONR 486.]
Processing for multipath effects
Authors: Rodgers George F. , Guthrie Priscilla E.
Published: October 2005

Two approaches to measurement of broadband data for TDOA are generated. Each uses two-channel, FFT-cascaded processing. The first, performed in the frequency domain is developed from edited, two sensor, phase data, using the MSC function. Phase dta are edited on the criterion of SNR. The second approach, performed in the time domain, is developed from split-beam sensor data. TDOA is estimated using the anti-correlation function. A model for the correlator approach was run at a range of SNR, −10 to +10 dB for a parametric range of TW products, 1–32. Variances in TDOA were measured for the model and compared to predictions. A 3-dB difference was noted, but not felt significant for the small statistical sample. The two approaches to TDOA measurement are compared and performance is predicted for each within given parameter bounds.
Acoustic propagation from deep-to-shallow water
Authors: Rubano L. A.
Published: October 2005

The results of explosive acoustic experiments performed off the coast of Panama City, Florida over two deep-to-shallow paths and one constant depth path are discussed and compared with the predictions of adiabatic mode models. Extensive seismic profiling, sediment coring, and velocimeter profiling provided model inputs. Mode-attenuation coefficients in one-third octave bands were obtained from an eight-element array and used to compare sediment absorption. In areas where mode-attenuation measurements were not feasible, absorption was predicted using a modified BIOT-STOLL model. Predicted and measured transmission loss in one-third octave bands from 31.5 to 4000 Hz are presented and discussed.
From Urbantschitsch to Davis: The first 70 years
Authors: Ward W. Dixon
Published: October 2005

The early history of research in temporary threshold shift (TTS) is recounted, from the pioneering paper by Victor Urbantschitsch [Arch. Gesch. Physiol. 24, 574–595 (1881)] to the World War II studies at Harvard's Psychoacoustic Laboratory [H. Davis et al., Acta Otolaryngol. Suppl. 88 (1950)] that involved exposure levels of 140 dB SPL. Highlights include development of the idea of TTS as a predictor of permanent hearing loss by Peyser, the discovery of multiphasicity in recovery by Bronstein, postulation of a critical intensity by Rüedi, and demonstration by Reid that exponential processes are involved. Problems encountered by these early workers that still vex us are briefly discussed, such as the definition of “pre-exposure threshold” (e.g., based on steady or intermittent tones, on that day's responses or on an average over many days), how fatigue should be expressed (threshold shift or shifted threshold, and in what units), and what constitutes “full recovery.” Finally, brief mention is made of some of the suprathreshold perceptual distortions associated with TTS: Changes in loudness, pitch, and timbre of tones and speech. [Supported by NINCDS Grant OH00350.]
Relation between binaural phase and amplitude differences in the perception of movement of a fused, lateralized sound image
Authors: Tansley Brian W. , Beverley Kenneth I.
Published: October 2005

A series of experiments investigated the interaction of phase and amplitude modulation in the auditory perception of movement of a fused, lateralized sound image. A technique was developed whereby the perception of periodic motion in the coronal plane of the head could be produced either by sinusoidal modulation of the amplitude or phase relation of a pure tone carrier presented to each ear. At a given modulation frequency the observer set the amplitude of either the phase shift or the differential amplitude change in order to just detect motion in the sound image. The threshold amount of each measure was defined as unity and the observer was then presented with various ratios of the two mixed in two ways: (1) Phase lead to one ear with amplitude increase to the same ear or (2) phase lead to one ear with amplitude increase to the other ear. Evidence for super additivity of amplitude and phase modulation was found for condition I while evidence for subadditivity for am and pm was found in condition number 2. Both these results suggest that, although both time and intensity differences are used by the human auditory mechanisms involved in the perception of movement, they have at least some different neural substrates.
Effects of signal frequency and masker bandwidth on detectability under diotic and dichotic listening conditions
Authors: Trahiotis Constantine , Appleby Michael
Published: October 2005

Detectability of a 200-ms sinusoid whose frequency coincided with the center frequency of a simultaneous narrow-band masking noise was investigated as a function of (1) frequency; (2) the bandwidth of the noise maskers, and (3) the mode of binaural presentation (N0S0 or N0Sπ). In the N0S0 condition, for a constant and narrow band of noise, thresholds of detection were relatively constant as frequency was increased in octave steps from 250 Hz to 4 kHz. In the N0Sπ condition, thresholds of detection increased dramatically as frequency was increased. The bandwidth and envelope characteristics of all noise bands were similar as a function of center frequency. Consequently, the data are interpreted as meaning that the detection of high-frequency sinusoids in the N0Sπ condition is degraded simply because the auditory system cannot use interaural time differences in the fine structure of such high-frequency waveforms.
Discriminability of interaural time disparities by normal and hearing-impaired listeners
Authors: Smoski Walter J. , Trahiotis Constantine
Published: October 2005

Thresholds of on-going interaural time difference (ITD) were obtained from normal-hearing and hearing-impaired subjects who had high-frequency, sensori-neural hearing loss. Utilizing several stimuli (a 500-Hz sinusoid, a narrow-band noise centered at 500 Hz, a 4000-HZ tone amplitude-modulated at 250 Hz, and a narrowband noise centered at 4000 Hz), four criteria for determining the level of presentation to each subject were employed: (1) Equal sound pressure level; (2) equal sensation level; (3) equal loudness; and (4) midline intracranial image. The ITD thresholds and slopes of the psychometric functions were elevated for hearing-impaired subjects for the two high-frequency stimuli in comparison to: (1) The subject's own low-frequency thresholds and (2) data obtained from normal-hearing subjects for stimuli presented with equal SPL interaurally. The ITD thresholds using stimuli level based on equal loudness and a centered image were slightly lower than those obtained using the equal SPL criterion.
Discrimination of duration at detection threshold
Authors: Widin Gregory P. , Colburn H. Steven
Published: October 2005

Levels were established for 70% detectability of 10- and 160-ms noise pulses in a noise background. These levels were used in three subsequent experiments: Detection with either duration possible, discrimination between the two durations, and a composite task requiring detection and discrimination responses on each trial. Detectability of the signals was approximately the same whether or not the subject was certain of signal duration. Discriminability of the signals was approximately the same for discrimination alone and in the composite task. A single integrator, which is optimally adjusted for each task and returns a single observation, does not account for these results. As observed elsewhere [e.g., Zacks, Science 170, 197–199 (1970)] equal detectability did not imply indiscriminability. Data from the present composite task indicate that discrimination between these low detectability signals is better than chance only on trials where correct detection actually occurs. [Work supported by NSF and NIH.]
The characteristics of a static and dynamic model of the vocal source
Authors: Al-Ansari A. , Badin P. , Guerin B.
Published: October 2005

We use a computer two-mass model of the human vocal cords to study the acoustic behavior of the vocal source. This model is directly controlled by two parameters: The subglottal pressure Ps and the cord mass-tension coefficient Q. The glottal signal issued from the model can be characterized by its fundamental frequency F0, the opening ratio QO, and the dissymmetry ration (or speed quotient) QD. The result of the static model simulation is in accordance with the previously obtained characteristics of the glottal signal [B. Guerin and L. J. Boe, Phonetica 37-3, 169–192 (1980) and J. L. Flanagan, K. Ishazaka, and R. L. Shipley Bell Syst. Tech. J. 54, 485–506 (1975)]. It indicates that the principal features of human vocal cord behavior are well presented by the static model. In order to see how the dynamic aspect can affect the static properties, we inject different slope pulses representing either the lung pressure or the cord mass-tension parameters in the two-mass model. These pulses are equivalent to that, induced by pushing on the chest or generated by laryngeal muscle activities of a phonating subject. We show that the variations of F0 and QO with P8 or Q depend on the sign and the value of the pulse slope. Their evolutions are separated from the static curves in an almost regular way, QD variations depend only on pulse slope value and scatter plot results for QD versus P8 or Q.
French vowel vocal configurations obtained by acoustical measurements
Authors: Lefèvre Jean-Paul , Lecours Michel , Tousignant Bernard
Published: October 2005

A method has been developed for the determination of the vocal tract area function from acoustical measurements. This approach is based on measurement at the lips of the response to an impulsive acoustic pressure wave, which is introduced at the lips [M. M. Sondhi and B. Gopinath, J. Acoust. Soc. Am. 49, 1867–1873 (1971)]. Such a technique presents many advantages, however, a number of precautions must be taken in data processing so as to take into account the specific requirements for such measurements. The vocal tract area function is modeled with reflection coefficients, these coefficients being directly identified from the knowledge of the incident and reflected waves measured at the lips. Numerous measurements with test cavities, then with human subjects have led to analyze and to refine the performance of this method, as well as its reliability. A systematic study of French vowel vocal configurations has been undertaken. For the first time, specific area functions related to a given subject are obtained. These measured configurations can be compared with the normalized results that have been reported in the literature.
Experimental and theoretical studies of topographical effects on sound propagation in the ocean
Authors: Akal T. , Jensen F. B. , Kuperman W. A.
Published: October 2005

Topographical features of the ocean sea floor can have a profound effect on sound propagation. Some of these effects have been studied both experimentally and theoretically. Propagation over sloping ocean bottoms as well as over shallow banks and seamounts have been studied experimentally using wideband techniques and theoretically using the parabolic equation and normal mode theory. Included in these studies are slopes ranging from less than one degree to fourteen degrees and ocean depths varying from 20–3000 m. Effects of topography on propagation levels and on the optimum frequency of propagation are discussed. Furthermore, experimental and theoretical results are presented where topography, bottom type, and sound-speed profile all change with range. The effect of smaller topographical features (bottom roughness) is also discussed.