bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative schlieren visualization
Authors: Stanic S.
Published: October 2005

Using a closed circuit television camera (CCTV), a method was developed to directly obtain quantitative sound pressure measurements from the sound fields imaged in a Schlieren system. By using the exact timed format of the composite video signal and a series of time delay circuits, it was possible to take vertical intensity scans of a Schlieren image at any position on the television raster. The method used the camera's horizontal blanking pulse to trigger a broadband, high-speed sample-hold amplifier. This amplifier was triggered to sample each of the horizontal scan lines at a selected time in the horizontal scan sweep and to feed this value into a transient recorder. The signal was digitized and a continuous analog voltage signal corresponding to the black-white information from a Schlieren image was displayed on a scope. The same analog signal was also plotted on an X-Y recorder. The ease with which the Schlieren system can be operated is evident from the fact that only a single calibration curve at each frequency was needed. The curves plotted applied transducer voltage against the video output level. Thus, by comparing the video output levels for several vertical image intensity scans on a Schlieren image, relative sound pressure measurements were routinely obtained.
Low-frequency acousto-optic schlieren
Authors: Buraro J. A. , Dardy H. D.
Published: October 2005

Schlieren visualization of acoustic waves is generally carried out at megahertz sound frequencies since, in a practical situation, lower-frequency waves are more difficult to observe. We have considered the factors involved in the sensitivity of acousto-optic schileren and have calculated minimum sound levels which could be observed in an ideal system at lower frequencies. The results indicate. and our experimental observations confirm, that low amplitude waves can be visualized in the 10–100-kHz frequency region. The factors involved in these sensitivity estimates will be discussed and a technique suggested which would make the sensitivity at these low frequencies comparable to that realized at the higher frequencies.
Quantitative visualization of scattered acoustic fields
Authors: Bucaro J. A. , Dardy H. D. , Moore W. E.
Published: October 2005

Two acousto-optic imaging techniques—schlieren and acoustic holography—are used to obtain quantitative images of the acoustic field scattered from a cylindrical target. The schlieren geometry is ideal for the near field of such a target, while the far field can be readily obtained with the holographic system. The implication of these results are discussed in view of the recently obtained capability of on-line digital processing of these images.
Sonic agglomeration: a promising method of enhancing the collection efficiency of electrostatic precipitators
Authors: Volk M. , Hogg R.
Published: October 2005

Experimental and theoretical studies of the effect of sound on the agglomeration of airborne particulates have been carried out to determine the feasibility of using sonic agglomeration as a means of enhancing the collection efficiency of electrostatic precipitators. Experiments were conducted using carbon black, kaolin clay, white lead, and fly ash aerosols. In each case, it was found that the rate of agglomeration increases with increasing concentration, sound pressure level, and exposure time, and with decreasing particle size. For each aerosol, there appears to be an optimum frequency at which the rate of agglomeration passes through a maximum. Experiments have also been conducted to determine if the efficiency of electrostatic precipitators, could be increased by pretreating the aerosol acoustically. Depending on the sound field conditions, the overall collection efficiency for the white lead aerosol was increased from 75% (on a mass basis) for the untreated aerosol up to as much as 90%. On the basis of these experimental results, it appears that sonic agglomeration has considerable potential for elimination of ultrafine particles prior to subsequent treatment using a conventional collection device such as the electrostatic precipitator.
Superdirective array performance in shallow water
Authors: Ozard J. M. , MacKinnon R. F.
Published: October 2005

The cross-spectral matrices of signal and noise were recorded for a superdirective array in shallow water. Well defined beam shapes were formed from the 4-min cross-spectral averages. Endfire configurations of three hydrophones equally spaced by 0.2 wavelengths enabled an array gain of 8.5 dB to be achieved at 136 and 230 Hz. The array weights used were adapted to an average measured noise field. If weights are optimized for an isotropic noise field an array gain of 7.5 dB is obtained.
Correction of inaccuracies in estimation of the narrow-band ambiguity surface
Authors: Marsh W. H.
Published: October 2005

A narrow-band ambiguity surface (NAS) is the coherence or correlation between two signals as a function of the Doppler difference and time delay difference between them. A peak in the NAS indicates the presence of a coherent relationship with specific Doppler and time delay differences between the two signals. An estimate of the NAS can be obtained by using time sequences of Discrete Fourier Transforms of the two signals and using a narrow-band approximation for Doppler compensation. This sort of compensation is required when processing propagation data, taken from a moving source. Inaccuracies may arise from the narrowband approximation when large numbers of degrees of freedom are used in the estimate. Such inaccuracies occur not only in coherence estimation, but in wide-band correlation estimation using FFT and inverse FFT for the correlation process if a narrow-band approximation is used for Doppler compensation. The nature of these inaccuracies is described and related to such factors as signal bandwidth, Doppler range, and integration time. Procedures are then outlined for minimizing approximation effects on the coherence estimate.
Transient interaction of an acoustic pulse with a finite cylinder within a fluid half-space
Authors: Sabbagh Harold A. , Krile Thomas F.
Published: October 2005

The transient interaction of an acoustic plane wave with a finite, cylindrical, elastic structure lying a fluid half-space is computed by utilizing N-port system theory. An N-port representation of the external fluid environment is obtained by solving a boundary integral equation relation between surface pressure and normal velocity. The Green's function for the integral equation satisfies a boundary condition for the fluid half-space. The N-port representation for the elastic structure is determined by first computing the normal modes by means of two-dimensional finite elements. The important modes considered are the longitudinal and lowest circumferential order flexural modes. The response of the coupled N-ports to the incident plane wave, whose temporal form is an exponential pulse, is obtained by a numerical inversion of Laplace transforms.
A community noise code. I. Background
Authors: Bounds S. E. , Garbak J. A. , Mendelsohn E. S. , Peppin R. J. , Whelan J. H.
Published: October 2005

Ever since emphasis for noise control in the community has become greater, noise codes, both simple and complex, have emerged from states and municipalities. Most “simple” codes are based on A-weighted standards while the “complex” codes are based on octave band or statistical criteria. Montgomery County, Maryland's noise code has become effective relatively recently. Based on an A-weighted sound pressure level measurement, it attempts to provide a means for quantitatively determining noise violations. This paper presents the background of the development of the code and the code requirements. It will be shown that the A-weighted code and its development may not be as simple as one would expect.
Model program to control motorcycle noise
Authors: Jura Russell D. , Hagie Roger , Harrison Robin T. , Walsh John B.
Published: October 2005

As a result of increased citizen concern about excess motorcycle noise, control of motorcycle noise is an issue of increasing importance to both governmental regulatory agencies and the motorcycle industry. The Motorcycle Industry Council (which represents most motorcycle manufacturers) has developed a model motorcycle noise control program which will allow governmental jurisdictions to effectively and reasonably control motorcycle noise. This program contains new vehicle sound levels and in-use vehicle sound levels, and also incorporates an exhaust system certification program. Implementation of this model program will enable a jurisdiction to control the manufacturer and the user, so as to ensure that only acceptably quiet motorcycles are sold, and that motorcycles once sold are maintained at the same acceptable quiet level. To be successfully implemented a jurisdiction must be willing to expand the necessary financial and physical efforts to enforce this program. This program, when properly implemented, should thus enable the jurisdiction to meet citizen concern about the motorcyle noise problem.
Some comparisons of traffic noise indices
Authors: Bradley J. S.
Published: October 2005

A major field study of human responses to traffic noise has been completed on 1200 subjects. Sites for noise and human response measurements were chosen on a deterministic basis so that the research was as much as possible a controlled experiment. Human response measurements were obtained from interviewer-administered questionnaires, and noise data from several days of digitally recorded data near the subjects' homes. Controlled variables included: type of road, size of community, type of dwelling, and socio-economic status. As a part of the overall study a number of traffic noise measures were evaluated as predictors of annoyance and activity disturbances. In general, the simpler measures (percentile levels and energy average level), were quite successful. Little improvement was gained by the use of the more complex measures incorporating terms relating to the fluctuating component of the noise. Data supporting the day—night sound level concept was obtained. [Supported by the Canadian Ministry of Transport.]
A sensitivity study of NOISEMAP power offset profiles
Authors: Holger D. K.
Published: October 2005

The USAF NOISEMAP computer program uses measured noise data for each aircraft in the inventory at selected reference power settings and airspeeds together with operational data for a given installation to predict noise exposure contours near the installation. The contribution from aircraft flying at other than reference conditions to the contours is computed through the use of offset profiles. The influence of offset profiles on noise contours was studied for seven bases selected to be representative of various aircraft type and operational situations. All computer runs made were for a complete set of actual operations for the bases chosen. Runs with actual-, modified-, and zero-power offset profies were made for each base. The simulations indicate that offset profiles may be important for only the statistically dominant aircraft at a base. [Work supported by USAF OSR.]
Development of an integrated airport noise model
Authors: Bartel C.
Published: October 2005

A set of computer programs, called Integrated Noise Model (INM), has been developed to compute noise exposure values due to aircraft at various locations around airports. The INM evolved from an earlier computer model used for investigating noise around 23 U. S. airports in terms of NEF. The INM consists of three independent routines: (1) Contour Analysis Model, (2) Grid Analysis Model, and (3) Contour Plotting Pack.age. INM will compute noise exposure values for the following: Noise Exposure Forecast (NEF); Day—Night Average Sound Level (Ldn); Community Noise Equivalent Level (CNEL); Aircraft Sound Description System (ASDS); and Daily Overall Sound Exposure (DOSE, an experimental noise metric). The calculations are sensitive to details of fleet mix data and flight operational procedures. The Contour Analysis Model develops points on curves of equal noise exposure. The Grid Analysis Model computes exposure levels at user-specified points. Optional output allows examination of the noise contribution from each flight. The Contour Plotting Package retrieves contour point locations from mass storage and plots them. [Work supported by U. S. Department of Transportation.]
Discrimination measurement and experimental design II. Phase and frequency discrimination using nine psychophysical procedures
Authors: Creelman C. Douglas , Macmillan Neil A.
Published: October 2005

In a paper presented at these meetings, Macmillan, Kaplan, and Creelman predict relative performance for several procedures for measuring discriminability. These predictions are tested tested for two sets of signals: tones differing in frequency, and sinusoidal octaves differing in the relative phase of the two components. Psychometric functions were obtained for both frequency and phase, with each of nine experimental procedures: yes—no; two-interval forced-choice (2IFC): AX, ABX, and AXA, each using both fixed and variable standards; and four-interval same-different. For the variable-standard designs, performance was ordered as predicted. Fixed-standard designs yielded performance somewhat better than yes—no, and 2IFC performance was better relative to yes—no than predicted by standard Detection Theory. Phase discrimination was better relative to yes—no and forced-choice than was frequency discrimination. The relations among various psychophysical procedures apparently depend on the sensory continuum under study.
Perceptual analysis of the amplitude envelope of AM signals
Authors: Bunnell H. T.
Published: October 2005

The manner in which the auditory system encodes the “shape” of the amplitude envelope of AM signals was examined. On the basis of modulation frequency tuned channels previously demonstrated for FM signals [R. H. Kay and D. R. Matthews, J. Physiol. (Lond.) 225, 657–677 (1972)] it was thought the auditory system might be responding to the power spectrum of the amplitude envelope. A 500-Hz carrier was amplitude modulated at 2, 4, or 8-Hz with either a sine wave or square-wave signal. The Method of Adjustment was used to determine the “modulation thresholds” for the 6 frequency by waveform conditions. At each of the modulation frequencies, subjects' thresholds were lower for square wave than for sine wave modulation. The mean ratio between the thresholds for the two wave forms was 1.32 with a SD of 0.22, which approximates 4/π (1.27) as would be predicted on the assumption that the auditory system performs a Fourier analysis on the amplitude envelope of the modulated 500-Hz tone. Additional data suggest that the two waveforms are indiscriminable until the third harmonic of the square wave reaches its independent threshold. Some implications for speech perception are considered. [Work supported by Penn. State Department of Psychology for partial fulfillment of master's degree.]
Response latencies are determined by the current stimulus and the current response criterion
Authors: Watson C. S.
Published: October 2005

There has been a recent renewal of interest in the response latency as a psychophysical index of detectability, discriminability, or perceptual magnitude. This response measure depends on a number of variables other than those of the stimulus and thus some care is required in its interpretation. It has been proposed that one of the most powerful determinants of response latency in discrimination tasks should be the distance of the current stimulus from the current criterion, measured along a decision axis. This proposition was demonstrated in nine experimental conditions, in which the tasks were (a) a difficult frequency discrimination, (b) an easy frequency discrimination, and (c) assignment of a two digit number to the correct one of two distributions. Each of these stimulus conditions was tested (1) in a standard statistical decision procedure, (2) with the optimal criterion demonstrated on each trial, and (3) in a “labeling” procedure without real or implied rewards. In all cases the response latencies fall off systematically to either side of the observers' current criterion, suggesting that the perceptual distance between the current criterion and the stimulus, rather than the inherent difficulty of a judgment, must determine the time required to process that stimulus. [Work supported by NIH.]
Revised perceptual-anchor model for context coding in intensity perception
Authors: Lira J. S. , Berliner J. E. , Braitin L. D. , Duriach N. I.
Published: October 2005

In large-range identification experiments, resolution is better near the edges of the stimulus range than in the middle. Similar changes in resolution occur in the vicinity of reference stimuli presented on a trial-by-trial basis. We have shown previously that these effects can be modeled by assuming that the observer uses the edges of the range and the reference stimulus (when present) as perceptual anchors and estimates the intensity of the stimulus to be judged by comparing it with these anchors [J. E. Berliner and N. I. Durlach, J. Acoust. Soc. Am. 54, 336 (A)]. In both the original and revised models, distances are measured by counting off “steps” from anchors, where the steps are assumed to be identically distributed random variables. Unlike the original model, in which the step size is infinitesimal, in the revised model the step sizes are assumed to be exponentially distributed with finite mean size (dependent on range). This assumption, together with the assumptions that the anchors are completely correlated and that the distance estimates are combined optimally, appears to permit a simpler and yet more rigorous description of context coding. [Work supported by NIH and NSF.]
Relationships among formant frequency measures of vowels in an “imitation” dialect
Authors: Papçun George
Published: October 2005

Twenty trained phoneticians of widely varying physical characteristics imitated vowels from Japanese, Spanish, and English under conditions designed to allow them to achieve maximally accurate imitation. In a previous report [George Papqun and Richard Harshman, “How do different speakers say the same vowels?” J. Acoust. Soc. Am. 59, S71(A) (1976)], discriminant analysis used with a subset of this data showed the necessity of using nonlinear terms in describing the overall phonetic space. In this report, regression and similar analyses are applied to vowels individually to examine the issue of which combinations of formant frequencies may be construed as representing one and the same vowel. [Work supported by USPHS and NSF.]
Voicing in the speech of language-delayed children
Authors: Bond Z. S. , Wilson Howard F.
Published: October 2005

Voicing as a phonological contrast emerges relatively early in the speech of children learning English. However, the acoustic realization of this contrast is quite complex. The purpose of this study was to investigate the details of the control of the voicing contrast in the speech of 10 children diagnosed as language-delayed in comparison with the speech of 10 children developing language normally. Each child was given a short test to determine if he could respond appropriately to minimal pairs differing in the voicing of stop consonants, and then recorded repeating 12 test words. Spectrograms of the three best productions of each word were analyzed, examining VOT differences between voiced and voiceless stops in initial position and the duration of the vowel preceding the stop pairs in final position. For all children, the control of VOT seemed to be in one of three stages of development: (1) overlap, (2) little overlap but great variability, (3) little overlap and decreased variability. A similar pattern of development, involving a decrease in overlap with a subsequent decrease in variability, was observed for vowel duration. Neither VOT nor vowel duration values comparable to adult values were achieved by the children.
Children's speech discrimination in quiet and noise
Authors: Elliott L. L. , Connors S. T. , Wier C. C. , Kille E. A. , Levin S.
Published: October 2005

Normal children 5–8 years old, were tested on a new speech discrimination procedure. Stimuli were monosyllabic nouns within the receptive vocabularies of three-year-old inner-city children. An up—down procedure tracked the 71% correct level of response. Open- and closed-set conditions were tested. Closed-set conditions used four-alternative picture responses. Subjects were tested in quiet with an open response set (no pictures) and then on three closed-set conditions: quiet, with a 12-talker-babble masker at 70 dB SPL, and with a filtered-noise masker (filtered to have the same spectrum as the babble) at 70 dB SPL. Thresholds in babble were about 10 dB higher than thresholds in noise, and open-set quiet thresholds were about 10 dB higher than closed-set quiet thresholds. No age differences were observed. The absence of an age effect with the monosyllable stimulus items contrasts with an earlier report [L. L. Elliott, J. Acoust. Soc. Am. 60, S28 A (1976)] where there was an age effect for older children tested in noise on a linguistically more complex task. [Supported by BEH.]
Phonemic errors of deaf children on a nonsense syllable test
Authors: McGarr N. S. , Stromberg H. , Hochberg I.
Published: October 2005

A closed response nonsense syllable test was developed to assess the reception of gross phonemic contrasts by deaf children. Test items were composed of V, VC, and CV syllables with the vowels /i,a,u/ and the consonants /m,s,g/. The test was administered over a two-year period (1975 and 1976) to one hundred 12–14 year old deaf children enrolled in schools for the deaf throughout New York State. Percentile plots showed improvement in overall performance over the two-year period. Greatest improvements were for vowels. Results indicated a pattern of errors similar to those reported by previous investigators for adults and adolescents [Pickett et al., in Speech Communication Ability and Profound Deafness, 119–133 (1970)]. These included: (1) scores for vowels were consistently higher than those for consonants, (2) scores for /u/ and /a/ were roughly the same and were in turn higher than the scores for /i/, (3) scores for the initial consonants were higher than scores for final consonants except for the nasal in which the reverse was true. [Work supported by Cooperative Research Endeavors in Education of the Deaf (CREED), Bureau for Special School Supervision, Office for Education of Children with Handicapping Conditions].
Palatalization of /l/ in Italian and Spanish
Authors: Javkin Hector
Published: October 2005

The palatalization of /l/ in Italian and Spanish presents an important case of the interaction of universal phonetic and language specific factors. In both languages, short, non-post-occlusive /l/ to /j/. Spanish palatalized geminate /l/ to /j/. Spanish palatalized geminate /l/ to /j/. These changes appear to be due to the fact that post-occlusive and geminate /l/ both have a higher tongue position than short, non-post-occlusive /l/: geminate /l/ due to a continuation of the tongue-raising gesture after the /l/ contact is reached; post-occlusive /l/ because the mandible is in a higher position following the occlusive. The higher tongue position alters the acoustic characteristics of the /l/ release, making it perceptually similar to a palatal glide. Both types of /l/ thus contain the phonetic conditions for a sound change. Why Italian and Spanish chose to palatalize only one of these types of /l/ (and why each made a different choice) is a question that the phonetician cannot answer. [Work supported by NSF.]
The declination effect
Authors: Breckenridge J.
Published: October 2005

The perception of the declination effect, which is the nearly universal tendency of intonation to drift downward in pitch, was investigated. The perception of this effect is interesting because it exemplifies the general problem of how the moving pitches used in intonation are processed and remembered. The stimuli for the experiments were nonsense sentences of the form “ma MA ma ma MA ma.” The pitch on one stressed syllable was varied by small increments and the resynthesized stimuli were randomizod before presentation. Subjects judged which peak was higher in pitch. A second peak with the same pitch as the first generally sounded higher. This demonstrated that the declination effect is psychologically real. The crossover point, or point of subjective equality, for wide pitch range stimuli reflected the large declination effect found in animated speech, whereas a negligible effect was found for narrow pitch range stimuli. A 3.6-dB increase in amplitude on the second stressed syllable shifted the crossover point downward to a surprising degree. Raising the pitch on the unstressed syllables made the second stressed syllable sound lower. [Work carried out at Bell Laboratories.]
On the establishment of oscillatory acoustic shock waves in monorelaxing fluids
Authors: Fenlon F. H. , Cohick S. M. , McKendree F. S.
Published: October 2005

Analytical approximations and numerical solutions exhibiting oscillatory shock formation in mono-relaxing fluids have been obtained for plane and spherical finite-amplitude waves. By comparing these results with previously reported oscillatory solutions of the Korteweg—de Vries (K—dV) and K—dV—Burgers' equation for plane wave propagation in a purely dispersive medium, necessary conditions have been established for the formation of osciliatory shock waves in mono-relaxing fluids. These conditions which are expressed in the form of dimensionless parameters of the medium and the propagating wave have been evaluated for particular relaxing fluid media. Several examples of the radiated intensities required to realize oscillatory acoustic shock waves at selected frequencies in such media will be provided. The “solitonlike” property of these oscillatory shock waves and those of the ideal “soliton” solutions of the longless K—dV equation will then be considered.
Demonstration of strong resonance of spinning model in annular ducts
Authors: Vaidya P. G.
Published: October 2005

When a single higher order model is generated in a rigid rectangular or narrow annular duct, at high enough intensities, generation of higher harmonics is observed. In the case of multimode inputs, the author and his collegues have shown theoretical results indicating the existence of strong acoustic—acoustic interactions at the first order of the perturbation scheme. This interaction would lead to energy being fed into both higher and lower harmonics. In this paper experimental results are presented, using a spinning mode synthesizer, which varify the theoretical predictions. Implications of these results for some of the practical problems have been discussed.
Outdoor propagation of spherically spreading acoustic waves of finite amplitude
Authors: Theobald M. A. , Webster D. A. , Blackstock D. T.
Published: October 2005

The outdoor propagation of spherically spreading sound of finite amplitude was experimentally investigated. The main purpose of the experiment was to determine the extent to which the outdoor environment, mainly random inhomogeneity of the medium, affects finite amplitude propagation. Periodic sources with fundamental frequencies of 6–8 kHz and source levels SPL1m from 140 to 149 dB were used. The sources were an array of horn drivers and a siren, The propagation path was vertical and parallel to an 85-m tower, whose elevator carried the traveling microphone. Measurements were made in late summer under a wide range of weather conditions. The inhomogeneities caused significant fluctuations in the instantaneous acoustic signal, but with sufficient time averaging of the measured harmonics levels, the results were comparable to results expected for propagation in a quiet medium. Propagation data for the fundamental of the siren approached within 1 dB of the weak shock saturation levels. Extra attenuation on the order of 8 dB was observed. The measurements generally confirmed the predictions of several theoretical models. [Supported by NASA, AFOSR, NOAA, and ONR.]
Propagation of monochromatic sound through a random noise field
Authors: Bourret R.
Published: October 2005

An analysis is given, using stochastic perturbation theory, of the propagation of a coherent monochromatic sound wave in a medium uniformly filled with acoustic noise of a given power spectrum. The results describe how the wave undergoes dispersion and attenuation as a result of the interaction with the noise field. Various easy and nontrivial generalizations are included as well as a discussion of the relevance of advanced acoustic propagators (Green's functions).
Comparisons between CM and apparent resistance changes in scala media
Authors: Hubbard A. E. , Geisler C. D. , Mountain D. C.
Published: October 2005

Potentials have been recorded from scala media of the guinea pig's cochlea while simultaneously delivering low frequency harmonically related tonal stimulation at the eardrum and electrical current into the scala. The recorded voltage signal contains energy at the primary frequencies, harmonics of those frequencies, and modulation products (sidebands). The demodulated sidebands (DBS) and the CM were analyzed using an FFT. Between 70 and 95 dB SPL, the magnitudes of the even harmonics of the CM and DSB vary somewhat proportionally. The odd harmonics, including the fundamental, are not so nearly scaled replicas of each other. Using a time-varying linear resistance hair-cell model, the DSB data can be interpreted as resistance change. However, linear time-varying resistance changes would produce DSB components proportional to corresponding CM components. A model which better fits these data is a time-varying current source in parallel with a fixed nonlinear resistor. [Supported by NIH grant NS 12732.]
A comparison of some measures of performance
Authors: Frank Alan S.
Published: October 2005

This paper compares the ability of various measures of performance to estimate P(A), the area under the ROC. The measures compared are PT(Y), the proportion of “yes” responses corrected for guessing; P(C), the proportion of correct responses; P(C)max, the maximum proportion of correct responses; d′ the normalized distance between the means of two equal variance normal distributions; and A′, a nonparametric measure [I. Pollack and D. A. Norman, Psychon. Sci. 1, 125–126 (1964)]. These measures will be examined assuming various underlying distributions: equal and unequal variance normal distributions, exponential distributions, Rayleigh and Rayleigh—Rice distributions and triangular distributions of both equal and unequal base widths. The measures are compared at different decision biases defined by likelihood ratio. The results show that across different biases, different underlying distributions and different variance ratios PT(Y) varies over the widest range of values, P(C) varies over a considerably smaller range of values but a slightly larger range than P(C)max, d′ or A′. P(C)max, d′ and A′ vary over approximately the same range of values. The practical implication of these results is that P(C)max, d′ and A′ are the preferred measures for describing performance in a single interval task. No one of the three measures can be selected as superior to the other two. [Work supported by PHS Mathematical Psychology Training Grant MH-11219.]
Binaural fusion in metathetic selective-attention tasks
Authors: Ahroon William A.
Published: October 2005

It has been suggested that some discrepant results of auditory attention research has been the result of the presence in some studies of an additional cue or dimension produced by the dichotic stimulus presentation which is not normally present during monaural contral conditions. For example, in two-channel prothetic discrimination or detection tasks, the presence of lateralization cues may be used by observers to overcome performance deficits caused by a limited ability to time share between the two (earphone) channels. The present study used binaural fusion as an additional (dichotic) cue which the observer could use to perform a two-channel simultaneous discrimination within a metathetic continuum. When binaural fusion was present, there were no performance deficits in divided-attention tasks relative to monaural conditions. Without this additional cue, performance in divided-attention conditions was significantly poorer than monaural performance. These results suggest that performance deficits in two-channel auditory selective-attention tasks are unrelated to prothetic versus metathetic continua or to detection versus recognition tasks.
Proposed shipboard noise and vibration monitoring system
Authors: Gafos Adamandios G.
Published: October 2005

In this paper the composition, operation, and performance capabilities of a shipboard noise and vibration monitoring system will be described. The uniqueness of this system is that it consists of readily available off-the-shelf instrumentation designed to measure or monitor both the mechanical and/or acoustic condition of shipboard machinery. For this particular application the system has been tailored for use aboard a new class of Navy ships.
Anchoring effects and vowel discrimination
Authors: Sawusch J. R. , Nusbaum H. C.
Published: October 2005

A series of synthetic, steady-state vowels varying perceptually from [i] to [I] was used in both identification and discrimination tasks under two conditions. In the control identification condition, each stimulus occurred equally often. Similarly, in the control ABX discrimination condition, each 1-step ABX trail occurred equally often. in the identification anchor condition, one of the endpoint stimuli occurred more often then the other stimuli. A similar change was made in the ABX anchor condition. In the identification anchor conditions, the category boundary between [i] and [I] shifted toward the more frequently occurring endpoint (anchor), relative to the equiprobable control. The peak ABX discrimination also shifted with anchoring toward the more frequently occurring stimulus (anchor). This change in discrimination performance rules out a response bias interpretation of the anchoring effect in identification. Rather, perceptual factors involving auditory memory or the reevaluation of vowel prototypes may be involved in the anchoring effects and recently reported selective adaptation effects for steady-state vowels. [Research supported by SUNY Research Foundation and University Funds grants.]
Perceptual assessment of vowel duration in consonantal context and its application to vowel identification
Authors: Mermelstein Paul , Liberman A. M. , Fowler A.
Published: October 2005

A consonant-vowel (CV) transition not only allows the listener to identify the consonant but it also affects the perception of the vowel. The transition influences both the perceived duration of the vowel and also its phonetic identity. Are these independent processes, or can the effect on phonetic identity be predicted from the duration effect? Synthetic vowels identifiable as /ɛ/ or /æ/ were preceded by 48 msec long /bV/ transitions incorporating linear variations in the format frequencies. In judging the duration of the vowel, listeners assigned to the vowel 27 msec of a 48-msec-long transition; the other 21 msec were presumably assigned to the consonant. As for the effect on the phonetic identity of the vowel, five of seven listeners showed a shift in the duration boundary that was essentially equal to the perceived increment in vowel duration contributed by the transition. Thus for them the contribution to perceived duration of the vowel predicts the shift in perceived phonetic identity. The other subjects' duration boundary shifts for vowel identification show greater scatter possibly indicating additional context-conditioned effects in vowel-identification performance beyond a mere change in the perceived duration value. [Research supported by NICHD Grant HD-01994.]
Near-perfect identification of speaker-randomized vowels without consonantal transitions
Authors: Kahn Daniel
Published: October 2005

While the two lowest formant frequencies, F1 and F2, are the most important cues in vowel identification, the correspondence between vowels and small regions in F1−F2 space is far from one to one when data from many speakers is considered. This fact suggests that our vowel-identification mechanism, quite reliable in ordinary speech situations, either (a) makes use of additional disambiguating cues, such as the frequencies of higher formants, vowel duration, degree of diphthongization, etc.; or (b) normalizes for individual-speaker differences by deriving information on vocal-tract geometry through exposure to consonantal formant transitions and known vowels; or both. The high vowel-identification error rates observed when isolated vowels are speaker randomized (43% in a recently reported experiment) argue that (a) is relatively unimportant vís-a-vís (b), since in such experiments all the types of information referred to in (a) are retained, yet vowel identification is not reliable. In this paper I argue that there exists a systematic bias favoring hypothesis (b) over hypothesis (a) in past vowel-identification tests and describe an experiment in which near-perfect identification scores were achieved despite speaker randomization and the absence of consonantal transitions.
Selecting syllable nuclei in French
Authors: Lennig Matthew
Published: October 2005

Monophthongal vowels are often said to be specifiable in terms of their target positions [R. Houde, SCRL Monograph No. 2 (1968)]. In this paper criteria for selecting vowel nuclei within syllables of free-running conversational French are described and evaluated for their ability to represent the impressionistic phonetic quality of measured vowels. Input to the nucleus selection algorithm is a syllable matrix whose rows contain the peak frequencies of the linear prediction model spectrum of the syllable at progressively later points in time. A fast method for eliminating gross errors (e.g., missing or extra formants) is proposed. This method is applied to each syllable matrix. Nuclei are then selected based on the steady-state criterion: The point of minimum rate of change of the first and second formant frequencies. Other nucleus selection criteria, such as points of inflection and extrema of the formant frequencies are compared to the steady state criterion with respect to their representational ability of perceived similarities and differences of vowel timbre. [Work supported by NSF.]
Perception of synthetic vowels in various formant and duration combinations
Authors: Cohill Edward N. , Danhauer J. L. , Herman G.
Published: October 2005

The vowels /i/, /a/, and /u/ were synthesized using a Nova minicomputer described earlier [G. Herman, J. Acoust. Soc. Am. 61, S68(A) (1977)]. Six normally hearing subjects made similarity judgments of the vowel stimuli which were constructed with the three formant frequencies published earlier for each vowel. The vowels had a rise-decay time of 20 msec. The formant structures of the vowels varied for four experimental conditions: (1) all three formants present; (2) F1 and F2 present, F3 absent; (3) F1 and F3 present, F2 absent; and (4) F2 and F3 present, F1 absent. Vowel durations of 200 and 300 msec were used for each condition. Twenty-four experimental conditions resulted and 576 stimulus pairs were used. Subjects listened at MCL and used an equal-appearing interval scale to make their similarity judgments. Ratings were converted to similarity matrices and submitted to INDSCAL to find perceptual dimensions. Features retrieved related to tongue height, tension, and advancement, with duration having less importance.
A developmental study of speech production: Data on vowel imitation and sentence recitation
Authors: Kent R. D. , Forner L.
Published: October 2005

Ten subjects in each of five groups (4-, 6-, 10-, and 12-year-old children as well as young adults) participated in a study involving the imitation of 15 synthesized vowels and the repetition of three simple sentences. This report emphasizes spectrographic data for the two youngest groups and the adult group. In the vowel imitation task, the subjects could recreate the relative formant structure of the targets, but the children in particular tended to produce allen (non-English) vowels as the proximal English vowels. Plotting of the formant data for different age-sex groups in the F1−F2 plane revealed linear orientations, i.e., isovowel lines for unnormalized data. Standard deviations for the first two formant frequencies of the imitations were commensurate with published data on difference limens for formant frequency. The sentence repetitions were used primarily to evaluate the stability of temporal patterns. Both the inter- and intrasubject standard deviations of temporal segments tended to be larger for the children than for the adults, but even some 4-year-olds occasionally fell within the adult range of variability. [Work supported by NINCDS.]
A comparative study of the perception of species-specific communication sounds by Japanese macaques (Macaca fuscata) and other Old World monkeys
Authors: Petersen M. R. , Beecher M. D. , Zoloth S. R. , Moody D. B. , Stebbins W. C.
Published: October 2005

An attempt is being made to psychophysically characterize the Japanese macaque's perception of sounds drawn from its vocal communication system. In the course of constructing a vocal ethogram for this species, Green (Primate Behavier 4, 1–101 (1975)] identified several distinct classes of vocalizations which differ in acoustic structure and form as well as the sociobehavioral context in which they are likely to occur. Six fuscata and three control (non-fuscata) monkeys have been operantly conditioned, via positive reinforcement techniques, to discriminate between two different types of vocal sounds from Green's classification scheme—the smooth early (SE) and smooth Late (SL) highs. While contacting a metal operandum with its hand an animal is presented a series of natural exemplars from the SL class. Occasionally, and randomly, an exemplar from the SL class is inserted into the series. If the animal correctly reports detection of the SE by breaking contact with the operandum it receives a food pellet. Results from several experiments employing this general procedure will be discussed including studies of perceptual constancy, selective attention, and the classification of synthetic versions of these communication signals. One important and consistent finding is that, although the fuscata and control animals have basically the same auditory capabilities, their perception of the communication sounds, at least during acquisition of the discrimination, differs: the fuscata seem to attend to the communication-relevant features of the sounds while the controls appear to attend predominantly to the communication-irrelevant aspects of the stimuli. [Supported by NSF Research Grants BMS 74-20050 and 5-27092, NINCDS Program Project Grant NS 5785, and NIGMS Training Grant GM-01789.]
A computational model for cochlear mechanics
Authors: Spenner B. F. , Cox J. R.
Published: October 2005

An integral equation model of the cochlea [M. D. Lien and J. R. Cox, Jr., J. Acoust. Soc. Am. 55, 432(A) 1974), J. B. Allen, J. Acoust. Soc. Am. 61, 110–119 (1977)] was revised by separating fluid mechanics and partition dynamics to allow computation of the response to complex stimuli and inclusion of nonlinear partition characteristics. The formulation is based on identifiable cochlear features: channel morphometrics and partition mass, resistance, and stiffness. Several simplifications not fundamental to the approach were used: Channel cross sections were assumed equal and independent of longitudinal position; dependence on the transverse coordinate was neglected; perilymph was assumed inviscid and incompressible; channel walls were assumed rigid except for the cochlear partition and windows. A spatial representation bandlimited by the number of computational elements was used, but otherwise no assumptions were made regarding the wavelength of the partition or fluid motion. The implementation of the model computes for an arbitrary input the instantaneous distribution of partition motion or the moving-window, discrete Fourier transform of partition amplitude and phase. [Work supported by NIH RR00396.]
Acoustic impedance measurements in infants and young adults
Authors: Walker James R. , Brenningstall G. N. , Stream K. S. , Stream R. W.
Published: October 2005

The ears of approximately 300 presumably normal-hearing young people were tested with the acoustic impedance bridge. About 50 subjects were between 18 and 30 years of age, the remainder were less than 16 weeks old. Tympanograms, acoustic reflex thresholds, and response patterns were investigated. Findings: Complicance of infants was consistently greater than adult normal limits; acoustic reflex can be elicited in a small percentage of infants; latency of contralateral reflex is approximately 10 msec greater than that of ipsilateral reflex; reflex response patterns, while highly variable among individuals, tended to fall into two classes (no significance has, as yet, been found for the dichotomy); no evidence was found to indicate that either sex or right/left handedness influenced responses. [Supported, in part, by Robert Wood Johnson Foundation.]
Quantification of the acoustic reflex latency parameters in humans
Authors: McPherson David L. , Thompson D.
Published: October 2005

This study defined and quantified reflex latencies in humans with normal auditory function and examined stimulus rise time in relation to changes in the acoustic reflex latency parameters. A carefully controlled and monitored 2000-Hz acoustic signal with four different rise times was presented 10 dB above each subject's clinical reflex threshold. The acoustic reflex response was photographed from an oscilloscope and read from a microfilm reader. The time course of the reflex responses was measured. Mean values for the latency parameters, maximum impedance changes, and acoustic reflex rise times were determined. It is proposed that latency be defined from the point of impedance change rather than from signal onset. This definition provides a less variable latency measure. Latency varied with intensity of the acoustic stimulus within the dynamic range of the reflex. It was not affected by other variables such as signal rise time, signal duration, or time constants of the electroacoustic impedance bridge. Latency of the acoustic reflex varied as a function of stimulus rise time and was energy dependent. [Work supported by HEW.]
Formant frequencies of some fixed-mandible vowels and a model of speech motor programming by predictive simulation
Authors: Lindblom Björn , Lubker James , Gay Thomas
Published: October 2005

Formant frequency data are reported for Swedish vowels produced both with fixed and unconstrained mandible. Measurements were made at the first glottal pulse to confine interpretation of the results to nonauditory feedback mechanisms. Results indicated that in spite of physiologically unnatural jaw openings, subjects were able to produce F patterns within the ranges of variation of the normal vowels. Results are explained by hypothesizing that the “instantaneous” learning of highly unfamiliar tasks, such as compensatory articulation of fixed-mandible vowels, is possible because normal speech motor programming is indeed “compensatory” rather than due to either speakers drawing upon past similar experience or invoking special motor mechanisms distinct from those of natural speech. That is, it operates in a context-sensitive mode to achieve listener-oriented goals. Since “contexts” constitutes an essentially infinite class of events the programming must be “creative,” or capable of handling conditions never before experienced. A model of speech production is proposed that achieves increased plasticity of motor control by incorporating an “upstairs” predictive component used to simulate “downstairs” processes of execution.