bluuebunny/crossref_metadata_2025 huggingface dataset:
Palatalization of /s/ in American English: when is a /š/ not a /š/?
Authors: Zue Victor W. , Shattuck-Hufnagel Stefanie
Published: October 2005

Acoustic measurement show that when /s/ or /z/ are followed by the palatal fricative /š/, they are often produced as /š/ or /ž/ in casual speech, even when the palatal segment is on the other side of a word boundary. Thus “gas shortage” can be rendered [gæššɔrɾəǰ]. A similar phenomenon might be expected in a different palatalizing environment, when word-final /s/ or /z/ are followed by the palatal glide /y/, as in “miss you” or “use your”. From the same corpus and using the same measurement procedures reported earlier [S. Shattuck-Hufnagel, V. W. Zue, and J. Bernstein, J. Acoust. Soc. Am. 64, S92(A) (1978)], we examined the acoustic consequences of this second palatalization process. Our measurements suggest that: (a) palatalization of word-final /s, z/ preceding a /y/ occurs quite frequently; (b) when such palatalization occurs, it results in acoustic characteristics which are uniform across the entire segment, with no residual alveolar fricative; and (c) for some speakers, the palatalization process results in acoustic properties significantly different from /š/ suggesting an articulatory target somewhere between the /s/ and /š/ in American English. [Work supported by N1NCDS.]
Surface duct propagation with ray to mode and mode to ray scattering
Authors: Bucker H. P.
Published: October 2005

There is often a mixed layer of water near the surface of the ocean which tends to trap sound with small grazing angles in RSR (refracted-surface-reflected) type propagation. This surface duct propagation is best described by normal-mode theory using a surface reflection coefficient S to represent sound energy scattered out of the modes at the surface. In this presentation additional integrals will be derived which represent energy scattered from high-angle rays into modes near the source and energy scattered from modes into high-angle rays that travel to the receiver. These integrals represent a significant part of the sound field when | S | ⩽ 0.9 and the source and/or receiver is below the duct. Also, a comparison of calculated and experimental data at 530 and 1030 Hz will be made showing good agreement between calculations and data. [Work supported by NORDA, Code 500.]
A discussion on finite-difference solutions to the parabolic wave equation
Authors: Lee Ding , Botseas George , Papadakis John S.
Published: October 2005

The application of numerical ordinary differential equation (ODE) methods for solving the parabolic wave equation has been presented at past symposia. These techniques were shown to be an efficient alternative to the usual solution via the split-step Fourier algorithm due to their stability and capability for a large step size in range. In this presentation, a solution based on finite differences is discussed. All three of the above techniques have been used to solve a number of representative, range-dependent, as well as range-independent, problems. The merits and disadvantages of each will be contrasted. [Work support jointly by NAVMAT and NAVSEA.]
Theoretical study of the penetration of highly directional acoustic beams into sediments
Authors: Tjötta Jacqueline Naze , Tjötta Sigve
Published: October 2005

Recently Muir, Horton, and Thompson [J. Sound Vib. 64, 539–551 (1979)] presented results of an experimental study of the penetration of directional acoustic beams into bottom sediments. We consider here the linearized theory of the refracted soundfield produced by a highly directional beam on a bottom sediment. A simplified equation valid for k′a tanθa ≫ 1 (k wavenumber in the sediment, k′ wavenumber in the overlaying water, a width of the incident beam at the interface, θa angle of the acoustic axis with the normal to the interface) is derived and solved analytically subject to the nondissipative boundary condition at the interface. The radiation field is found to be similar to that of a phase shaded piston source. The solution is valid whenever the characteristic length of the diffraction effects, which is of order (a;/k′ sin2θa1/2, is small compared to the attenuation length in the sediment; this is the case in the experiment referred to. When k′ sinθa < k, the refracted soundfield is a beam with axis in the direction predicted by the ray theory. At critical incidence, the axis lies along the interface. When k′ sinθa > k, there is also penetration into the sediment that the beam structure is practically lost in this case.
Acousto-optic sensor comparison
Authors: Cole J. H. , Lagakos N. , Bucaro J. A.
Published: October 2005

Optical devices for detecting acoustic signals are currently under investigation in a number of laboratories. These sensors operate by modulation of the optical intensity or phase. A comparison of the relative merits of phase and intensity modulation is discussed. Theoretical estimates of sensitivities are compared to available experimental data.
A parametric acoustic source with an endfire primary projector
Authors: Moffett Mark B. , Konrad William L.
Published: October 2005

A new type of parametric acoustic source configuration utilizes an endfire projector for the primary beam. This configuration shows promise for those applications requiring a projector having small frontal area, e.g., a source to be towed. A small endfire projector consisting of 20 half-wavelength elements at 30 kHz in line with 20 half-wavelength elements at 35 kHz was built and tested at NUSC's Dodge Pond test facility. The resulting difference-frequency beam patterns compare favorably with nearfield beam pattern predictions when the actual primary patterns (which deviate from ideal endfire shape) are taken into account. [Work supported by Naval Material Command.]
Adaptation to changes in aircraft noise exposure
Authors: Fidell S. , Horonjeff R. , Teffeteller S. , Pearsons K.
Published: October 2005

Changes in the pervasiveness of community annoyance associated with a series of major changes in aircraft noise exposure in the vicinity of an airport with appreciable air carrier traffic were assessed. Repeated rounds of interviews at intervals of several weeks were conducted in four neighborhoods near the airport before and after the changes in exposure. Attempts were made, both in person and by telephone, to administer a brief and direct questionnaire to adult residents of all affected households in each neighborhood while concurrent long term noise exposure measurements were being made. Findings include substantial immediate effects of exposure changes, while suggesting the time course of adaptation to aircraft noise exposure.
Results from an attitudinal survey dealing with impulse noise
Authors: Schomer Paul D.
Published: October 2005

The Army has completed a major attitudinal survey in the vicinity of one of its major bases. In this survey, subject responses were compared amongst five types of sources in order to compare and “calibrate” the Army types of noise as compared to more normal, urban types of noises. The specific types of sources included: blast sources, helicopters, fixed-wing aircraft, traffic, and children and pets. Several types of analyses have been completed and will be discussed. These include the growth of community response to the various types of noises as functions of sound amplitude, and event frequency of occurrence. The existence and numerical value of nighttime and evening penalties is discussed and attributes which make the various types of noise sources bothersome to people are compared. Finally, the percent of respondents “highly annoyed” as a function of the noise climate is discussed and several variations in formulation of the “noise climate” are utilized.
Utilization of community noise attitudinal survey data to effect program policy changes
Authors: Fricks Patti Thiel , Ranck Richard B.
Published: October 2005

A community noise assessment survey was conducted in Salt Lake City, Utah to estimate individual and group variations in attitudes and responses toward noise. The data generated from the survey provided local noise control officials with an evaluation of the existing noise program, identification of specific problem sources of noise in the city, identification of noise control measures supported by community members, an assessment of the health and welfare effects of noise on residents, and perceptions of noise as an environmental hazard in the community. By stratifying the population of the city according to 14 homogeneous noise zories and eight geographical areas, the needs of various sections of the community became apparent. An analysis of the public's awareness of the existing noise control program and the effectiveness of that program was used to influence program policy changes. Based on survey data, certain geographical locations and noise zones were identified as in need of program strategy changes in the areas of public awareness, land use planning, and enforcement. The survey allowed local noise control officials to establish a comprehensive noise abatement plan addressing critical areas in need of immediate attention and long-range program goals.
Pattern masking and pattern unmasking effects in auditory detection
Authors: Woods David D. , Sorkin Robert D. , Boggs George J.
Published: October 2005

The detectability of a sinusoidal signal was observed to vary as a function of the organization of a series of five tones rapidly presented prior to the signal. In one condition all context tones were lateralized (by an interaural intensity difference) towards the ear contralateral to the signal. In a second condition all tones alternated ear of lateralization. Only the pattern of lateralization distinguished these conditions. In addition, a potential masker occurred either immediately prior to the signal or two tones prior to the signal. In the former case, the effect of the masker on detectability decreased when the sequence alternated ear of lateralization (pattern unmasking). In the latter case, the effect of the masker increased when the sequence alternated ear of lateralization (pattern masking). Masker-signal interactions in the absence of the other context tones did not account for the observed effects. In general, signal detectability was a function, not of the characteristics of the tone immediately prior to the signal, but rather of the characteristics of the tone prior to the signal in the same perceptual channel (as defined by ear of lateralization). [Work supported by NSF.]
Tone-on-tone masking in the chinchilla
Authors: Long Glenis R. , Miller James D.
Published: October 2005

Greenwood [J. Acoust. Soc. Am. 50, 502-543 (1971)] found that measurements of masking with the signal (fg) higher in frequency than the (fm) revealed a region of lower thresholds (notch) due to the detection of the 2fm − fg combination tone. He argued that this masker-notch interval provides a measure of the width of the apical segment of the traveling wave on the basilar membrane. In an attempt to estimate this width in chinchillas, masked thresholds with fg < fm were obtained from three operantly conditioned chinchillas. The maskers used were 50 dB SPL tones at 1000 and 1500 Hz. Two notches were found at each frequency, one of which was independent of masker frequency and was probably due to the perception of amplitude modulations. The other, most likely the notch described by Greenwood, was dependent on masker frequency. The masker-notch intervals obtained are not consistent with Greenwood's claim that the width of the apical segment will occupy a shorter distance, in millimeters, on the basilar membrane of an animal such as the chinchilla than it does in man. [Work supported by NINCDS Grant NS03856.]
Internal noise estimates and noise bandwidth
Authors: Spiegel Murray F. , Green David M.
Published: October 2005

A brief 1000-Hz sinusoid served as signal in a two-interval forced-choice detection task. The noise waveform was digitized and in each of the two intervals either independent or identical waveforms were presented. Assume detection is based on waveform energy with internal Gaussian noise added to each sample. Detection performance is determined by the signal-to-noise ratio and the level of internal noise. We can therefore calculate estimates of noise levels using decision rules appropriate for each test condition. For narrow-band noise (WT = 1) or wide-band noise (WT > 100) these estimates are similar for either independent or identical noise samples. In the narrow-band case the signal-to-noise ratio needed for a constant detection performance is smaller than the wide-band case by almost 10 dB. Despite this change the internal noise estimates remain the same. [This work was supported by an NIH grant and post-doctoral fellowship.]
A temporal model of speech production
Authors: Bell-Berti F. , Tuller B.
Published: October 2005

Attempts to model speech production processes based on abstract static units, such as syllables, phonemes, or features, fail to account for a number of observations of natural speech. For example. a phonetic feature such as lip rounding has been described as being anticipated varying numbers of consonant segments before the vowel for which it is specified. Such data conform to predictions made with models assuming a CnV syllable structure. Such models, however, fail to predict nasality anticipated in vowels preceding nasal consonants. On the other hand, feature-based models that apparently account for observations of anticipated nasality fail to predict other coarticulatory phenomena, such as the suppression of lip-rounding or tongue-fronting activity during the production of an intervening consonant presumably containing no conflicting articulatory gesture. A model assuming that speech is specified segmentally with fixed timing relationships between the end and beginning of successive segments (and variable durations of dynamic gestures) can eliminate these, and other, discrepancies between predicted and observed behavior. [Work supported by NINCDS and BRSG grants.]
Backward normalization in the perception of temporal speech cues
Authors: Pind Jorgen L.
Published: October 2005

Two experiments will be reported which have investigated, for Icelandic, the effects of number of subsequent syllables in a word on the perception of vowel quantity (cued by duration) and preaspiration (cued by voice-offset time). The first experiment randomly varied the duration of the stressed (first syllable) vowel and the number of syllables (one, two, or three) in a word. Results showed that the vowel duration needed to cue a long vowel depended on the number of syllables in the test word. The second experiment investigated the value of voice-offset time needed to cue preaspiration in the first syllable of one-, two- or three-syllable words. Preliminary analysis shows backward normalization similar to but smaller than that found for vowels. Both experiments demonstrate that the perceived category of a phone can depend on information occurring after the immediately following syllable. [Work supported by the Icelandic Science Foundation.]
Cue trade offs of spoken fricatives: Duration and intensity of the noise and vocalic formant transitions
Authors: McCasland George P.
Published: October 2005

Spoken /s/ was manipulated using both PCM and splicing techniques, and perceptual results were obtained from a group of native American subjects. Prevocalic /s/ noise as in /sa, si/ must have sufficient intensity and duration to override a /θ/ percept produced at weak noise levels by the conflicting place cue of the natural vocalic transitions. In one intervocalic context determined by a final /i/ vowel as in /sasi, sisi/, the /s/ requires even greater noise intensity and duration to override the conflicting labial cue of the combined arresting and releasing transitions, which produces an /f/percept with weak noise. Postvocalic /s/ as in /has, his/ requires the least noise energy because the vocalic transitions contribute to the place impression of the /s/ percept. In all of these contexts, a shorter, more intense /s/ noise segment has the same cue strength as some longer, less intense segment in overriding conflicting transition cues. This investigation extends work on fricatives previously reported by the author [J. Acoust. Soc. Am. 63, S21(A) (1978); 65, S78(A) (1979); and 66, S88(A) (1979)]. [Haskins Laboratories has provided valuable assistance in the preparation of stimuli on Contract No. N1H-71-2420, National Institutes of Health, HEW.]
Experimental detection of boundary diffraction waves irradiated by an impulsively excited line source of finite length
Authors: Rudgers Anthony J.
Published: October 2005

It has been shown theoretically that the transient acoustic pressure field radiated by a finite line source comprises three distinct components: a spatially discontinuous cylindrical wave (“geometrical wave”) and two directional boundary-diffraction waves radiated by the ends of the line. This model of the structure of the pressure field, which is that predicted by the Rubinowicz-Maggi diffraction theory, has also been demonstrated experimentally. The experiments were conducted in a water tank. Bursts of pseudorandom band-limited white Gaussian noise were used to impulsively excite a line transducer electrically. By crosscorrelating these signals with the acoustic signals that the transducer radiates, and by using a computer to filter the resulting crosscorrelation functions, the waveform of the transducer's spatial impulse response was obtained at a number of observation points in the source transducer's radiated field. The experimentally obtained waveforms agree closely with those predicted by the theoretical calculations.
Standards Committee S2 on Mechanical Shock and Vibration
Authors: Eshleman R. , Booth G.
Published: October 2005

Working group chairpersons will present reports of their recent progress on writing and processing letter ballots on various shock and vibration standards. In addition, there will be a report on the interface of S2 activities with those of ISO/TC 108 (the Technical Advisory Group for ISO/TC 108 consists of members of S2, S3, and other persons not necessarily members of those committees). The Technical Advisory Group meeting will be held jointly with the meeting of Standards Committee S2.
A review of the acoustical aspects of hush house design
Authors: Vér I. L.
Published: October 2005

This paper reviews the acoustic requirements, the acoustic performance of hush houses, and the present state of available design information. Emphasis will be placed on dry-cooled-type facilities. Experience gained, through model studies and through performance evaluation of recently completed facilities, will be cited. The conflict between acoustical aerodynamical, aerothermal, and structural design requirements, and cost limitations will be discussed and the need for close cooperation between acoustical aerodynamical, aerothermal, and structural designer and the close consultation with future user, as a prerequisite for a balanced design, pointed out.
An exploratory survey of noise levels associated with a 100-kW wind turbine
Authors: Balombin J. R.
Published: October 2005

During the past few years, NASA's Lewis Research Center has managed a wind turbine project for the Department of Energy. This effort has included the design, construction, and operation of a 125-ft-diam, 100-kW wind turbine at the NASA Plum Brook Station near Sandusky, Ohio. During some of the performance tests, the opportunity arose to make exploratory noise measurements and results of those surveys are presented. The data include measurements as functions of distance from the turbine, and directivity angle, and cover a frequency range from 1 Hz to several kHz. Potential community impact is discussed in terms of A-weighted noise levels relative to background levels, and the infrasonic spectral content. Finally, the change in the sound power spectrum associated with a change in the rotor speed is described.
Resonant porous material absorbers for use underwater
Authors: Moore James A. , Lyon Richard H.
Published: October 2005

A theory for the propagation of sound in a resistive porous material is developed that is formulated in terms of the bulk elastic properties of the material making up the structure of the porous material and the permeating fluid. Impedance relations are developed for characterizing the acoustic behavior of a layer of porous material of finite thickness. The acoustic behavior of resistive screens and impervious septa is also characterized. The sound absorption characteristics of different coating configurations consisting of arrangements of porous material layers, impervious septa, and resistive screens are evaluated analytically. A novel design configuration is presented for achieving low-frequency sound absorption in a thin coating design. The dynamic behavior of the design is explained in physical terms. Several potential material embodiments of the design are presented.
Reflection behavior of linear slip interfaces
Authors: Johnson Richard K. , Schoenberg Michael
Published: October 2005

A linear slip interface is one across which tractions are continuous but normal or shear displacements may be discontinuous [M. Schoenberg, J. Acoust. Soc. Am. 66, S2 (1979)]. At low frequencies, the slip interface is equivalent to a thin low impedance layer. If the compliance has nonzero real part, it will produce a frequency-dependent reflection coefficient. In this paper, we describe the reflection behavior of a system consisting of an acoustic half-space, an elastic layer, a slip interface, and an elastic half-space. The frequency response of this system is affected by both the thickness resonance of the elastic layer and the compliance of the slip interface. Comparisons are made with a similar system lacking the slip interface and with a system in which the slip interface is replaced by a thin low impedance layer.
Basilar membrane mechanics in the guinea pig cochlea—Comparison of normals with kanamycintreated animals
Authors: LePage Eric L. , Johnstone Brian M. , Robertson Donald
Published: October 2005

Basilar membrane mechanical responses were recorded from seven guinea pigs which had been treated with kanamycin sulphate (400 mg/kg for 8 to 10 days) and kept for different survival times so as to result in different levels of degeneration of the outer hair cells and organ of Corti. Following mechanical recording the cochleas were immediately prepared for scanning electron microscopy [D. Robertson and B. M. Johnstone, J. Acoust. Soc. Am. 66, 466–469 (1979)]. The mechanical responses to impulses differed from normal increasingly with the state of degeneration of the outer hair cells. Loss of the outer hair cells appear to correlate with loss of the vulnerable nonlinearity. The differences were pronounced in older animals in which the organ of Corti was totally missing, notably the impulse response continued to ring for longer. The cutoff frequency was raised and the phase curve lacked the rapid roll segment. These results indicate that, contrary to the widely held view, the structure of the organ of Corti exerts a significant influence on the motion of the basilar membrane on the apical end of the traveling wave envelope.
Mechanical techniques for enhancing damping in viscoelastic layers
Authors: Junger M. C.
Published: October 2005

Representative mechanical techniques for enhancing strains and consequently energy dissipation in viscoelastic layers applied to structures are described. In the familiar constrained damping treatment the viscoelastic layer is bonded to a shear strain-enhancing light metal facing. Other configurations described here utilize inertia as well as elastic forces to enhance both compressive and shear strains, thereby also acting as tuned dynamic absorbers. Stave damping treatment calls for a viscoelastic layer sandwiched between a pipe or beam and parallel metal rods. A recent generalization of this concept consists in dispersing small metal spheres or rods, preferably of varying size, through a relatively thick viscoelastic layer bonded to one plate or sandwiched between two plates.
The effectiveness of some recent damping treatments in the reduction of the vibration of fluid-loaded finite plates
Authors: Thomas Richard W. , Macaluso John A. , Wilson Geoffrey L.
Published: October 2005

The driving-point impedances of center-driven free square plates coated on one side by commercially available damping treatments, two trowelled on and two in the form of tiles cemented on, have been measured and compared with those of an uncoated reference plate. The tile treatments were found to be the most effective in reducing the vibrations of both air-loaded and water-loaded plates. The increase in loss factor was found to be greater than that caused by fluid loading, indicating that their application to the internal portions of a submerged body should reduce the energy available for transfer into the ambient medium as acoustic sound waves. Measurements of the sound level in the direct field of the water-loaded plates have shown that these two treatments caused the greatest reduction in the sound radiated by the plates.
Effects of stress and utterance position on stop voicing
Authors: Flege J. E. , Brown W. S.
Published: October 2005

Duration and glottal pulsing are known to distinguish voiced from voiceless stops in certain phonetic contexts. This study examined the effect of stress and position-within-utterance on these temporal and laryngeal correlates of stop voicing. Eight talkers produced utterances consisting of from one to five tokens of/pápa/or/bába/. The duration of stops and vowels was measured from intraoral air pressure traces sensed via a tube inserted in the mouth. The output of a throat microphone was used to calculate the percentage of stop closure intervals showing signs of laryngeal activity. It was found that a laryngeal contrast between/p/ and /b/was maintained in all positions except utterance-initial position. Vowels were consistently longer before /b/ than /p/. The closure of /p/was longer than that of /b/ everywhere except in utterance-initial position. Thus, the supra-segmental factors which affect segment duration obscure a temporal correlate of phonological voicing only in utterance-initial position where neither vowel duration nor glottal pulsing distinguish /p/ from /b/. None of the three correlates of stop voicing, however, were importantly affected by variation of stress placement.
Psychophysical tuning curves for phonetically relevant acoustic information
Authors: Miller Joanne L. , Connine Cynthia M.
Published: October 2005

In a series of experiments we have begun mapping psychophysical tuning functions for acoustic information that is used in specifying segmental distinctions. Our procedure is a modified selective adaptation technique, whereby we systematically vary the value of the adaptor along the dimension of interest and measure the magnitude of shift in the phonetic boundary. To date, we have found, as might be expected from previous research, that the magnitude of the adaptation effect increases as the distance between the adaptor and the phonetic boundary increases. More importantly, we have found that the shape of the tuning curve beyond the asymptotic value systematically differs as a function of the particular acoustic dimension under test. For example, for a voice-onset-time (VOT) continuum specifying a syllable-initial voicing distinction, the effect remains at maximal level across a wide range of values (at least up to + 175 ms VOT); whereas, for a continuum of second-formant transitions specifying a syllable-initial place distinction, the curve falls after asymptote, more closely resembling a typical psychoacoustical tuning curve. The significance of these findings for describing both the effective information for specific phonetic distinctions, and the operation of the mechanisms that process that information, will be discussed. [Supported by NIH.]
Scaling of glottal opening
Authors: Löfqvist A. , Baer T. , Yoshioka H.
Published: October 2005

Laryngeal control mainly occurs along two dimensions. One involves the longitudinal tension of the vocal cords and is used for F0 control. Speakers can normally exert very fine-graded control in this dimension, and it is used extensively for linguistic purposes. The other dimension is that of abduction-adduction, involved in the control of phonation type, voicing, and aspiration. From published records, it appears that more than two or three distinct degrees of glottal opening are rarely used during speech production in different languages. The present experiment was designed to clarify the control of glottal abduction-adduction and examines how many degrees of glottal opening speakers can produce consistently under various static and dynamic nonspeech and speech conditions. Glottal opening was monitored simultaneously by a fiberscope and a transillumination system. Preliminary results indicate that without training and visual feedback subjects can only produce gross abduction and adduction gestures and are unable to make finely controlled variations of glottal opening. [Work supported by NINCDS and BRSG.]
Urban light motor vehicle noise levels at close-in distances for a worst case situation
Authors: Hruska Gale R. , Williams Kent C.
Published: October 2005

Effective motor vehicle noise enforcement in many urban areas can only be accomplished if measurements are made relatively close to the vehicle. To help define reasonable enforcement levels, in situ sound level measurements were recorded in four geographical locations for 8307 light weight motor vehicles accelerating from rest or near rest. To insure a “worst case” situation, the microphones were positioned at 3.81 m from the centerline of travel and 27 to 46 m from the initial point of acceleration. The data were partitioned into three “acceptable” vehicle classes and one class which included all vehicles judged to have had defective or modified exhaust systems, or had been unreasonably driven. Analysis of the data shows that the “unacceptable” vehicle distribution has a mean sound level at least 6 dBA greater than those obtained for all of the “acceptable” classes. Relations between the posted speed limits and the mean values of the observed sound levels were obtained.
Impact of an industrial hearing conservation program on occupational injuries for males and females
Authors: Schmidt J. W. , Royster L. H. , Pearson R. G.
Published: October 2005

The recorded entries of job-related injuries were examined for employees of a cotton yarn plant in North Carolina for equal time periods before and after the advent of a hearing conservation program. Audiometric test data had previously been collected and analyzed, and were available for inclusion in this study. The number of reported injuries for a group of workers employed a minimum of 11 consecutive years decreased significantly after the advent of the hearing conservation program. This is evident when classifying employees both by age and by years of service. Improvement of injury rates was found to be greater for females than males. Comparison of injury rates for two small groups of employees having worked the same number of years during either high noise exposure or reduced noise exposure showed significantly lower injury rates for the workers employed only in the reduced noise condition. An overview of the findings indicates that a reduction in employee noise exposure contributed to a lower injury experience for the population studied.
Flow-induced tones in side branch pipe resonators
Authors: Pollack M. L.
Published: October 2005

Acoustic tones generated by turbulent flows and shear-layer-instability interactions with side-branch resonator pipes were investigated experimentally using fast Fourier transform techniques. The experimental values of resonant frequencies and instability frequencies were compared with predictions for two stages of shear-layer interaction. Relative tonal amplitudes are shown to demonstrate cut-in and cut-out phenomena. The qualitative differences between turbulent-flow-generated tones and instability-generated tones are also noted.
Syllable stress and vowel identity
Authors: Rakerd Brad , Verbrugge Robert R. , Shankweiler Donald P.
Published: October 2005

Variations in syllable stress create a constancy problem for vowel perception owing to the accompanying variations in formant structure. An earlier study [R. R. Verbrugge and D. P. Shankweiler, J. Acoust. Soc. Am. 61, 539 (1977)], failed to demonstrate perceptual “compensation” for stress changes, possibly because variation in the prosody of a carrier phrase was not effective in altering the perceived stress of the target syllables. In the present experiment, stress was varied by altering the acoustic structure of the target syllable itself. A male talker produced a set of carrier sentences containing either stressed or destressed /pVp/ syllables (V = /i, , ε, æ, a, , , ν, u/). Two types of synthetic analogs were created using an OVE-III synthesizer: (a) original formant analogs, matched in pitch, amplitude, duration, and formant frequencies to the original syllables, and (b) interchanged-formant analogs, preserving the original prosody, but containing formants taken from the syllable of opposite stress. The synthetic syllables were embedded in the original carrier sentences for presentation to listeners. Vowel identification was influenced by perceived stress: errors on stressed formants increased somewhat when the prosody was inappropriately destressed, while errors on destressed formants were paradoxically lower in the presence of stressed prosody. The results demonstrate that vowel identity is perceived in relation to stress. Comparison of error patterns for stress-interchanged and rate-interchanged syllables suggests that the two transformations are not equivalent. [Research supported by NICHD.]
Toward a principle of perceptual continuity in speech
Authors: Remez Robert E.
Published: October 2005

The speech signal is a heterogeneous sequence of whistles, clicks, hisses, buzzes, and hums. Within limits, it has been possible to point to acoustic correlates of particular phonetic segments that are often held to underlie phonetic perception. Two aspects of this framework motivate the present research. First. the sequence of acoustic cues forms a continuous perceptual stream, albeit one composed of linguistic units. Second, the acoustic cues to speech sounds trigger phonetic percepts only when presented within a speech stream. How, then, shall we conceptualize the mutual dependency of speech stream and phonetic cue? This research begins to describe the differences between those heterogeneous spectral sequences that possess continuity and those that do not. Synthetic noise bursts differing in center frequency were paired with synthetic vowel formant patterns. When burst+vowel patterns possess continuity, listeners hear a CV syllable. When burst+vowel patterns lack continuity, listeners hear a nonspeech “snap” followed by a vowel. Naive listeners used either of two closed response sets in identifying the items: (1) [p], [t], and [k], or (2) [p], [t], [k], and “snap.” The results reveal that perceptual continuity plays a role in the extraction of segmental identity from acoustic patterns. [Supported by NIMH].
On the concept of integrated scattering strength and its relation to the theory of scattering by single particles and target strength
Authors: Maples Louis C.
Published: October 2005

A simple concept of integrated scattering strength is developed from the fundamentals of volume and boundary (surface) scattering and shown to be identical to the target strength of a single scatterer as evolved from the theory of scattering by single particles utilizing the target area or effective cross section of the scatterer as the primary measure. The concept applies equally as well to surfaces such as plates as to solids and volumes, such as rigid or elastic spheres or shells. In order to arrive at a complete specification of integrated scattering strength, particularly for irregular objects, a comprehensive array of statistics is required, from the basic framework of which a simplified. ready-reference set of numbers may be derived for simple, but meaningful, comparisons of scattering effectiveness.
Standards Committee S3, Bioacoustics
Authors: Yost W.
Published: October 2005

The current status of standards under preparation will be discussed. In addition to those topics including hearing conservation, noise, dosimeters, hearing aids, etc., consideration will be given to new standards which might be needed over the next few years.
Application of acoustic intensity to diesel engine noise reduction
Authors: Hammer William G.
Published: October 2005

Acoustic intensity is being used daily by Detroit Diesel Allison on its diesel engine noise reduction programs. Instrumentation and test technique used will be described. The total sound power nearfield versus farfield will be compared in addition to showing the source analysis of two engines. The advantages of acoustic intensity will be demonstrated by showing the results of evaluations of experimental exhaust manifold covers and air box covers.
Computer simulation of static localization cues
Authors: Davis Mark F.
Published: October 2005

A system for imposing static (fixed-head) localization cues on an artificial sound source is described. The system is based on the measurement of the peripheral binaural impulse responses at a series of target source positions using small microphones in the subject's ear canals. A computer with associated waveform processing software convolves these impulse responses with widehand noise bursts and plays the results to the subject over headphones. The headphone impulse responses are also measured and deconvolved out of the waveforms in advance by the computer. Both live and simulated localization trials have been carried out, using an identification paradigm with unconstrained source and subject-response positions. Two-dimensional, weighted error analysis is used to derive performance scores. Psychophysical localization performance with the simulator is compared to equivalent live performance.
The acoustic impedance of a layered forest floor
Authors: Talaske Richard H.
Published: October 2005

An analysis of the normal incidence acoustic impedance of the forest floor in coniferous and deciduous forests was performed by treating the forest floor as a layered medium. The acoustic properties of both individual layers and combinations of layers were measured. To determine the acoustical properties of individual orgenic layers, the techniques presented by Delany and Bazley, and Pyett were utilized and compared to direct measurements. Also, an analysis of the physical characteristics of the organic layers and mineral soils was performed which included flow resistance, bulk density, porosity, moisture content, and other parameters. Pyett's estimates of impedance compared well with direct measurements. The predictions of impedance using Delany and Bazley's method were found to not accurately predict the characteristic acoustic impedance and propagation coefficients of the organic materials tested. Statistical analysis of the measurements in the forest indicate that the presence of an organic layer on mineral soil significantly reduced the impedance when compared to bare mineral soil. These field measurements were also compared to computed values of impedance using an analytical model and compared well with the measured values of impedance. [This research was done in association with the Noise Control Laboratory at Penn State University. The author, at the time of presentation of this paper, will be employed with R. L. Kirkegaard and Associates, Lombard, IL 60302.]
Atmospheric use of ray acoustics
Authors: Roth S. David , McDaniel Oliver H.
Published: October 2005

It is commonly known that in nonhomogeneous media (phase velocity dependent on location) refraction of acoustic signals occurs. Solving the wave equation with variable c is often extremely involved and the cases where solutions can be found do not give very much insight into the physical meaning of the problem. The method of ray tracing, the solution of the eikonal equation, readily adapts itself to nonhomogeneous media and describes the propagation of wavefronts. It has been used extensively in underwater acoustics but not very much in atmospheric applications. With the relatively recent development of concern over noise pollution there has been increased interest in understanding how the atmosphere affects sound propagation. Ray tracing is seen as a useful method in studying propagation in air and also as a method to predict the sound field at a receiver. Computer models for ray-tracing and evaluation of eigenrays have been developed. Use has been made of these models to predict when noise from a distant source will be a problem.
Effects of masking noise on auditory-nerve coding of vowels
Authors: Voigt H. F. , Sachs M. B. , Young E. D.
Published: October 2005

We have previously reported on the representation of steady-state vowels in terms of both average rate and temporal aspects of the discharge patterns of populations of auditory-nerve fibers [Sachs and Young, J. Acoust. Soc. Am. 66, 470–479 (1979); Young and Sachs, J. Acoust. Soc. Am. 66, 1381–1403 (1979)]. The previous results were based on recordings made in the absence of background noise. In this paper we report the results of a study in which responses of large populations of auditory-nerve fibers to steady-state vowels were recorded in the presence of broad band background noise. Evidence will be presented that in the CF ranges between the formant frequencies, responses evoked by the background noise can be suppressed by presentation of the vowel. At noise levels high enough to drive units into rate-saturation, phase-locked responses to the vowel can still be observed. [Supported by Grant No. NS12112 from NINCDS.]
Differential behavior of endolymphatic potential (EP) and cochlear microphonic (CM) during substrate free vascular perfusion
Authors: Kambayashi J. , DeMott J. E. , Comegys T. H. , Thalmann R.
Published: October 2005

The EP and CM start to decline following 85 ± 20 (SD) min of substrate free vascular perfusion in the guinea pig. Initially the decline of the CM can be accounted for entirely by the reduction of the EP. The EP then stabilizes around +30 mV and even increases temporarily (+9.8 ± 4.3 mV), while the CM continues to decline to an asymptotic level of 80% below normal. This indicates a metabolic deficiency of the organ of Corti despite a low metabolic rate and sizeable glycogen stores. We have evidence that the stabilization and recovery of the EP is only in part due to a reduction of its (hypothetical) negative component. Recently we reported that the 8th nerve action potential (AP) could not be maintained beyond 60 min of perfusion with glucose containing media [Thalmann et al., J. Acoust. Soc. Am. 66, S47 (1979)]. We have since found that, by elevating the flowrate substantially above the “critical rate” of the CM and EP, and AP increases beyond normal by varying amounts (up to threefold) with marked input/output changes. We suspect that this phenomenon is not a true physiological response, but an artifact due to damage of nerve trunk and brain stem resulting from microsurgical manipulation. [Supported by NIH.]
Stress contrasts in the speech of the deaf: acoustic measurements
Authors: McGarr Nancy S.
Published: October 2005

The study examined the acoustic manifestations of contrastive stress in perceived correct and incorrect utterances of a deaf speaker. The utterances were of the form /əpipap/ or /əpapip/ with stress on either /i/ or /a/. Judgments of perceived stress were obtained from inexperienced listeners of deaf speech and tokens were then sorted according to the perceived and intended productions. Acoustic measurements were made of parameters known to vary with stress in normal speakers including changes in vowel duration, fundamental frequency, amplitude, and formant frequency. No obvious consistent strategy was apparent in the deaf speaker's manipulation of the acoustic characteristics of correct and incorrect utterances. Relationships among these parameters in correct or incorrect productions will be discussed. [Work supported by NINCDS and BRSG.]
Reliability of a nonsense syllable test
Authors: Dubno Judy R. , Dirks Donald D.
Published: October 2005

The reliability of a closed-response set nonsense syllable test [S. B. Resnick, J. R. Dubno, S. Hoffnung, and H. Levitt, J. Acoust. Soc. Am. 58, 114 (1975)] was determined on a group of 38 listeners with mild to moderate sensorineural hearing loss. Eight randomizations of the 91-item test (four trials on each of two days) were presented monaurally, under earphones, at 90 dB SPL with a cafeteria background noise set at a +20 dB speech-to-noise ratio. Performance under these conditions ranged from 21.4% to 91.2%, reflecting the wide range of syllable-recognition ability of these subjects. Reliability of the eight measurements was determined by analysis of variance and analysis of covariance structure (parallel-test modelling) for the entire test and each of 11 subtests. Overall and individual subject results failed to show any systematic differences in scores over eight trials. Likewise, no significant differences were found in performance on individual syllables, nor were changes in the relative occurrence of specific syllable confusions noted. This test is highly reliable when evaluating hearing-impaired subjects, and thus is appropriate for use in investigations where identical items are administered under multiple experimental conditions.
Growth of the simple difference tune and cubic difference tone with input level: Influence of f2/f1
Authors: Humes Larry E.
Published: October 2005

The present investigation examined the effect of f2/f1 (where f1 and f2 are the frequencies of a two-tone input, f2 < f1) exerted on the slopes of the functions relating simple difference tone level [L(f2 − f1)] and cubic difference tone level [2(f1 − f2)] to input level (L1 = L2, where L1 and L2 represent the levels of the tones at f1 and f2, respectively). Two normal-hearing young adults served as subjects. An adaptive 2AFC nonsimultaneous gap-masking paradigm was utilized to obtain estimates of distortion product magnitude. Parameters of the two-tone input were: f1 = 1550 Hz; f2/f1 = 1.08 and 1.41; and L1 = L2 = 35 to 85 dB SL. Results revealed that slopes for the functions relating L(f2 − f1 and L(2f1 − f2) to L1 = L2 were approximately 1.0dB/dB for f2/f1 = 1.08. For f2/f1 = 1.41, however, a slope of 2.0 dB/dB was observed for L(f2 − f1) while a slope of 3.0 dB/dB was obtained for L(2f1 − f2). It is suggested that some combination of nonlinearities is needed to account for these data.
Recall of hierarchically structured melodic sequences
Authors: Deutsch Diana
Published: October 2005

Two experiments are described which investigate recall of hierarchically organized melodic sequences. An adaptation of the technique of melodic dictation was employed, in which musically trained listeners notated each sequence after it was presented. All sequences were 12 tones in length. Pronounced effects of sequence structure were demonstrated. For those sequences that could be parsimoniously encoded in hierarchical fashion, near-perfect recall was obtained. Performance was substantially inferior for sequences that could not be parsimoniously encoded. The effect of temporal segmentation was also investigated, and this was found to have a powerful effect on perceived structure, virtually overriding that of tonal structure. Temporal groupings tended to be retained or lost in an all-or-none fashion. These findings are related to the theoretical assumption that we encode tonal materials by inferring sequence structures and alphabets at different hierarchical levels, together with rules of combination. [Work supported by NIMH.]