bluuebunny/crossref_metadata_2025 huggingface dataset:
The contribution of CV transition duration to the perception of final-consonant voicing in natural speech
Authors: Raphael L. J. , Dorman M. F.
Published: October 2005

The experiments reported here were attempts to replicate the results of previous research which had employed synthetic stimuli [Raphael et al., J. Acoust. Soc. Am. Suppl. 1 57, S49(A) (1975), and 58, S57(A) (1975)]. A speaker recorded a single token of the syllable [sεd]. Under computer control the syllable was edited to produce three continua: [sεd] to [sεt], created by deleting pitch pulses from the vowel; [dεd] to [dεt], created by deleting the [s] friction from the [sεd-sεt] continuum; and [εd] to [εt], created by deleting the initial transitions from the [dεd-dεt] continuum and reiterating pitch pulses from the vowel to compensate for the duration of the deleted transitions. For each continuum listeners were asked to identify the final consonants as voiced or voiceless. The [d]-[t] phoneme boundaries, plotted as a function of vocalic duration, fell within 3 ms of each other, indicating (as did the earlier experiments) that initial CV transitions contribute equally with “steady-state” formants to the perception of that vowel duration which cues final-consonant voicing. [Work supported by NICHD.]
Relation of peak intraoral air pressure to tone
Authors: Zee Eric
Published: October 2005

Much attention has been paid to the differences in peak intraoral air pressure between voiced and voiceless stop consonants. The present study, however, explores the differences in peak intraoral air pressure in voiceless unaspirated bilabial stop consonant [p] in a CV syllable where V is produced with different tones. Native speakers of three Chinese dialects which have different tonal systems participated in the investigation. The results show that there is a positive correlation between the peak intraoral air pressure in [p] and the onset F0 value of the tone that occurs on the following vocalic element. The results are discussed in terms of possible physiological explanations, such as the use of a higher subglottal pressure to produce a higher F0. [Research supported by NSF.]
Comparison of measured acoustic propagation characteristics over uniform terrain with a point-to-point prediction model
Authors: Tate D. C.
Published: October 2005

Extensive acoustic tests were conducted to simulate traffic noise to determine variations in the sound field over uniform terrain due to various surface impodances and various types of sound-impeding barriers. The tests were conducted indoors to provide exercise control over environmental parameters affecting acoustic propagation. Special data from 500 Hz to 31.5 kHz were measured for four source heights at various distances from the source and heights above the surface. Two sets of these exercises, hard uniform terrain (infinite impedance) and uniform terrain with finite impedance obtained by covering the floor with carpet, were selected for comparison with predictions from a model developed by Thomasson. The Thomasson model, provided in the form of a computer algorithm, was adapted to predict receiver levels corresponding to the measured data. During implementation, modifications to the basic algorithm were required to eliminate computational overflow and underflow errors. Predictions of spectra and sound pressure level summations over frequency and source travel distance were computed and compared with both the infinite and finite impedance measured data. [Work jointly supported by NCHRP and FHWA.]
Computer-controlled experiment for scaled indoor measurements of traffic noise propagation effects
Authors: Tate D. C. , Lawther J. M.
Published: October 2005

A series of acoustic measurements have been completed, simulating traffic noise produced by automobiles and trucks. In order to provide controlled tests, scaled measurements were conducted in a large gymnasium using a 5:1 scale factor. An automated, computer-controlled system was specially designed to complete the large number of measurements required. A remote-controlled cart simulated the traffic vehicles. A digital computer controlled the tests, collected and processed the raw data for quicklook analysis, and recorded both the raw and processed results for detailed postrun analysis. Measurements were made simulating uniform terrain with the hard floor for infinite impedance terrain and covering the floor with carpet for finite impedance terrain. Sound field variations due to sound-impeding barriers of various shapes were also measured. This paper presents an overview of the measurements conducted and the data collection-processing systems, and illustrates some of the measured results. [Work jointly supported by the NCHRP and FHWA.]
Semantic ratings of annoyance judgments of sounds
Authors: Elliott T. F. , Wilbanks W. A.
Published: October 2005

A frequently cited, though rarely examined, factor in human annoyance by sound is that of meaning, i.e., information which a sound conveys to the listener concerning the nature of its source. A method is described by which the effect of meaning on judgments of annoyance by sound may be quantitatively examined. Thirty-six environmental sounds, grouped into three general cognitive categories (transportation, common household, and miscellaneous) were presented via earphones to listeners at two intensity levels (72 and 92 dB SPL). Annoyance judgments were made by subjects on 2 seven-point semantic rating scales (noisiness and acceptability). Information as to the identity of sound sources was limited by brief exposure to the sounds and brought under a degree of experimental control through a method of labeling. The effectiveness of this method as a means of studying the effects of meaning on sound annoyance will be discussed.
Models for acoustic propagation over ground theory and experiment
Authors: Hayek S. I. , Lawther J. M. , Nobile M. A.
Published: October 2005

Analytic models which predict the propagation of noise from a point source to a point receiver over an impedance covered terrain have been used in this investigation to predict the sideline noise received from an incoherent line noise source. The point to point propagation models include a direct, a reflected, a ground wave, and sometimes a so-called surface wave. Different authors have given different forms of the solution. The incoherent line simulates traffic noise and is located at the accepted source height having the spectrum of an automobile, a light truck, or a heavy truck. To validate these models, tests were made on 1:5 scale model in a gymnasium covered by carpets that simulate grassy terrain. A carriage carrying a set of nine height-adjustable speakers is moved along a line to simulate traffic noise. Each speaker is pulsed with pure tones, so that the nine speakers reproduce 19 third octave components of the simulated traffic noise spectrum. A set of 16 microphones are used to record receiver field. In general, the agreement between the theoretical prediction the experiment was good except for receivers near the ground when the levels were overpredicted. [Work supported by NCHRP and FHWA.]
Ultrasonic measurement of third-order elastic constants of fused silica
Authors: Breazeale M. A. , Fischer M.
Published: October 2005

A finite amplitude ultrasonic wave propagating through a solid generates harmonics whose magnitudes are determined by some of the third-order elastic constants. Other third-order elastic constants determine the magnitude of the variation of ultrasonic wave velocity as the sample is subjected to hydrostatic pressure. We have combined results of harmonic generation experiments and pressure variation of ultrasonic wave velocity to evaluate third-order elastic constants of fused silica. We used four different samples having different hydroxyl ion content and different homogeneities and obtained the following results.

OH

content C111 C112 C123

Sample (ppm) (1012 dyn/cm 2) (1012 dyn/cm 2) (1012 dyn/cm 2)

Suprasil W1 5 6.70 ± 0.12 1.81 ± 0.09 1.77 ± 0.16

Suprasil W2 5 6.85 ± 0.06 1.64 ± 0.06 1.59 ± 0.12

Suprasil 1 1200 7.31 ± 0.07 1.69 ± 0.14 2.16 ± 0.11

Suprasil 2 1200 6.75 ± 0.07 1.79 ± 0.07 1.80 ± 0.11

The relationship between these results and results available from other techniques is discussed. [Research supported by the Office of Naval Research and by NATO.]
Grüneisen gamma from solid nonlinearity parameters: A generalized approach
Authors: Cantrell John H.
Published: October 2005

Generalized Grüneisen parameters which measure the strain derivatives of the lattice vibrational frequencies are often used to test atomic theories of crystalline solids and to model their anharmonic properties. The relationship between these parameters and the solid nonlinearity parameters measured directly in ultrasonic harmonic generation experiments is derived using a generalized approach valid for normal mode acoustic wave propagation in any crystalline direction. The resulting Grüneisen parameters are purely isentropic in contrast to the Brugger-Grüneisen parameters which are of a mixed thermodynamic state. The equations are specialized to the case of longitudinal wave propagation in the three pure mode directions of cubic crystals in order to compare available experimental data.
Velocity and attenuation measurements in metal waveguides
Authors: Frost H. M. , Prout J. H.
Published: October 2005

Noncontacting electromagnetic-ultrasound transducers (EMT's) have been used on metal rods and tubes [H. M. Frost, Physical Acoustics, Vol. XIV, edited by W. P. Mason and R. N. Thurston (Academic, New York, 1979), Chap. 3]. Work is scarce, though, on wire or on inhomogeneous or roughly surfaced waveguides. Too, scientific use of EMT's is slowed by measurement errors from EMT-waveguide gaps varying during scanning. We report on a two-transducer (sender-receiver) setup for (nonferromagnetic) wire with 12- to 1-mm diameters. Nondispersive torsional pulses with ∼10-μs durations are transduced by Lorentz forces on stationary and moving wire, without access to wire ends. Velocities for alloy wire and graphite/aluminum metal matrix composite wire agree well with prior shear wave values at megahertz frequencies for corresponding “bulk” material. Oscilloscope and x−y plotter data for moving wire illustrate measurement sensitivity to artificial flaws yet insensitivity to transducer-wire gap variations. Early work on three- and four-transducer setups indicates even greater capability for measurement precision and accuracy and application to nondestructive testing and to surface acoustic waves. [This work was supported in part by NAVSEA 62R4.]
The measurement of hearing protector attenuation via ASA STD1-1975 (ANSI S3.19-1974)
Authors: Berger E. H.
Published: October 2005

E-A-R® Corporation has recently completed construction of a hearing protector attenuation measurement facility that complies with the requirements of the new real ear attenuation standard, ASA STD1-1975 (ANSI S3.19-1974). The test room is a 113-m3 a double walled, mechanically isolated chamber. All significant acoustical, physical, and electrical requirements of ASA 1 will be discussed as they relate to the performance of the E-A-R facility. Topics will include sound field uniformity, diffusivity, and background noise level measurements. Experiments were also conducted to determine open ear hearing threshold levels of 12 subjects and compare them to ISO R226 (corrected for diffuse field listening). Agreement was good. Additional data was acquired for pulsed versus nonpulsed thresholds and “noisy” versus silent subject response switches. These results as well as those of some hearing protector attenuation data will be presented and finally comparisons will be made between attenuation data from at least two independent testing laboratories.
The appropriate sound level for auditory warnings on civil aircraft
Authors: Patterson Roy D. , Milroy Robert
Published: October 2005

A method for establishing the appropriate sound level for the auditory warnings on the flight decks of commercial aircraft has been developed. First, the spectrum of the flight-deck background noise is measured and auditory threshold is determined as a function of frequency using a recent model of auditory masking. This general threshold curve is then used to establish the range of appropriate levels for the spectral components of warning sounds. Finally the spectrum of a particular warning is compared with the band of appropriate levels to determine which spectral components dominate the perception of the sound, and the overall level of the warning is adjusted so that these crucial components fall within the range of appropriate levels. The procedure will be illustrated for two aircraft —a Boeing 727 and a BAC-11. The analysis shows that some of the warnings are far too loud; for example, in both cases, the under-carriage warning is 20 dB above the maximum of the range of appropriate levels. [This research was supported by the Civil Aviation Authority of Great Britain.]
Survey of hearing function in ambulance paramedics
Authors: Johnson David W. , Hammond Robert J. , Sherman Robert E.
Published: October 2005

Fifty-two subjects (51 males and 1 female) employed by a major medical center as paramedicals in ambulance service were evaluated with pure tone audiometry from 0.25 to 8 kHz. All subjects were asymptomatic for hearing problems. Amount of time on the ambulance service ranged from a mean of 2.2 years for the youngest age group (18-24 years) to 15 years for the oldest age group (55–59 years). Specific heating threshold was established for each frequency for each subject. Hearing thresholds for each age/sex/frequency category were compared to presbycusis standards derived from Spoor [Int, Audiol. 5, 48–57 (1967)] and Hinchcliff [Acoustica 9, 303–308 (1959)]. Deviations from derived standard values in standard deviation units were averaged across age. Though the amount of hearing loss was not great, data suggested hearing was poorer than mean expectations for the given frequencies with larger differences noted at 0.25, 0.5, 6, and 8 kHz. Preliminary interpretation of data is guarded because of lack of regional-based presbycusis norms.
Spectral structure of pressure measurements made in a combustion duct
Authors: Miles Jeffrey H. , Raftopoulos D. D.
Published: October 2005

The spectral structure of pressure measurements made in a ducted combustion test facility are studied. Dispersion and attenuation of acoustic plane waves may occur in the duct at low frequencies due to combustor emissions and affect the spectral structure. A model that considers the propagation of plane waves through a cloud of particles in a flowing gas and which includes heat transfer between soot particles and the gas is discussed. Experimental results are compared with theory.
Detectability of time-varying interaural correlation
Authors: Grantham D. Wesley
Published: October 2005

In a two-interval, forced-choice task, observers were to discriminate a binaural noise whose interaural correlation, r, varied according to the function r(t) = m cos 2πfmt from an interaurally uncorrelated noise [NU; r(t) = 0.0]. The former stimulus produces a perceptual binaural “flutter,” where the flutter rate is equal to the modulation frequency fm, and the amount of flutter corresponds to m. The stimuli were narrowband Gaussian noises with center frequencies of 0.5, 1.0, 2.0, or 4.0 kHz. Presentation level was 75 dB SPL; duration was 1.0 s. For a given modulation frequency, modulation “depth,” m, was varied in a blocked procedure, and thresholds were estimated from the psychometric functions as that value of m required for 75% discdminability. For the 0.5-kHz stimulus. thresholds increased from m = 0.28 at fm = 1 Hz to m = 0.78 at fm = 50 Hz. For higher-frequency stimuli, discrimination was generally poorer and the function relating threshold m to fm was flatter: thus, for 2 kHz, m = 0.56 at fm = 1 Hz, and m = 0.71 at fm = 20 Hz: for 4 kHz, m = 0.80 at fm = 1 Hz, but no thresholds could be determined for fm < 5 Hz. The data will be discussed in relation to previous work on dynamic binaural processing. [Supported by NSF.]
The temporal course of the masking of tinnitus
Authors: Penner M. J.
Published: October 2005

For 20 patients with tinnitus, we found that the intensity of broadband noise required to mask the tinnitus increased (by as much as 45 dB) during 30 rain of noise exposure. in contrast, the intensity required to mask an external tone remained nearly constant. Some speculations which might account for these results are offered. We posit that excess neural activity is the physiological determinant of tinnitus, and that the excess activity is central, generated in the brainstem postsynaptic to the eighth nerve. [Work supported by NIH.]
Design and testing for rail vehicle shock environment
Authors: Herring J. M.
Published: October 2005

This presentation is a review of techniques used by The Budd Company to design for the shock environment experienced by rail cars. Additionally, there is a discussion of techniques proposed for the future. There are brief discussions of the ride quality, stability, and wayside vibration models presently used. The structural test procedure for truck frames and dynamic tests for suspension systems used are described. The future introduction of a nonlinear analytical model and variable load structural tests are also described.
On the fall of the declination theory: breath-group versus “declination” as the base form for intonation
Authors: Lieberman P. , Tseng C. Y.
Published: October 2005

The “declination” theory [S. Maeda, “A Characterization of American English Intonation,” MIT dissertation (1976)] claims that a linear fall in fundamental frequency throughout a sentence characterizes the language-universal base form for sentence intonation. This theory is tested by deriving fundamental frequency contours from read sentences and actual discourse in English and Chinese, taking both intra- and inter-speaker variation into account. The data refute Maeda's claims; fundamental frequency, in general, does not show a linear fall throughout a sentence, nor can a linear “declination” line be derived for local fundamental frequency peaks or valleys. The most consistent acoustic markers of the end of a sentence are a terminal fall in both fundamental frequency and amplitude accompanied by an increase in the relative duration of the last word or syllable. These data are consistent with the breath-group theory [P. Lieberman, Intonation, Perception and Language (MIT Press, Cambridge, MA 1967)] as well as traditional analyses of intonation.
Intonation of restrictive and nonrestrictive relative clauses in English and Spanish
Authors: Garro Luisa L. , Parker Frank
Published: October 2005

Some investigators have commented on the intonational differences between restderive (RRC) and nonrestrictive relative clauses (NRRC); however, none of them provide instrumental evidence for their claims. In order to test the differences, identical utterances containing both clause types were recorded from speakers of English (Southern American dialect) and Spanish (River Plate dialect) so that lexical peculiarities would not affect the outcome. Broad and narrow band spectograms were made of each utterance. Three significant variables emerged: (I} pitch [fo] fluctuation and (2) vowel length in the word preceding the pause, and (3) the pause length preceding and following the relative clause. Variation of these parameters indicate that both clause types are accompanied by characteristic patterns of intonation and juncture in both languages, although no major differences were found between languages. RRCs typically have sustained or rising pitch; NRRCs display rising-falling or falling-rising pitch. RRCs have a shorter vowel and pause, while NRRCs lengthen either one or both. However, these characteristics are not always present simultaneously. In sum, intonation may well provide information for decoding relative clauses, in addition to that supplied by their syntactic and lexical structure.
Effects of vowel duration on stress boundaries in disyllables
Authors: Smith Mary R.
Published: October 2005

In a previous study of stress perception using nine disyllables, it was found that the ratio of duration of the first vowel to that of the second which distinguished first and second syllable stress (the stress boundary) was not independent of the identity of the two vowels. [Smith, J. Acoust. Soc. Am. Suppl. 1 66, S87 (1979)]. The present study had two purposes: first, to determine if the observed relative distribution of boundaries was specific only to the durations used in that experiment, and second, to test the hypothesis that stress boundaries could be expressed as a ratio that would be invariant with respect to changes in rate. The same nine disyllables of the form /s_ds_d/with fixed formant patterns for each of the vowels /i/, /I/, and /ɝ/ were synthesized. For each form the duration of the first vowel was varied in 10 ms steps across three ranges: the original 50 to 150 ms, 80 to 240 ms, and 110 to 330 ms. Listeners reported the stress of isolated words presented in a block design with one range per block. The relative ordering of boundaries was not preserved entirely across the three ranges. The ratio description of stress boundaries describes the data only for the three words in which both syllables contain the same vowel.
Sound-silence patterns and the perception of speech rate
Authors: Feldstein Stanley , Crown Cynthia L.
Published: October 2005

An earlier study [S. Feldstein, J. Acoust. Soc. Am. Suppl. 1 60, S46 (1976)] found that the sound-silence sequence of monologues yielded a measure of speech rate highly correlated with words-per-minute. The present exploration asked whether listeners use the sound-silence sequence in their perceptions of speech rate. Thirty 1-min speech segments were presented in three forms: as originally recorded; in pitch-scrambled form that kept stress and intensity contours intact but not words; in “tone-silence” form in which all speech sounds were changed to 1200 Hz tones and only the sound-silence pattern remained intact. Of the 30 segments, ten were spoken at an ordinary rate of speed, ten rapidly, and ten slowly. After each segment, listeners rated the speed at which it was spoken on a ten-point scale. Analyses indicated that the magnitudes of the mean ratings increased appropriately from “slow” to “ordinary” to “fast” segments for the three segment forms, but differences among the ratings were not significant for the “tone-silence” form. Apparently, listeners were unable to reliably use only sound-silence patterns to detect speech rate.
R-matrix theory of sound scattering from an absorbing bubble
Authors: Gaunaurd G. , Überall H.
Published: October 2005

The R-matrix theory of acoustic scattering, developed by us earlier [G. Gaunaurd and H. Überall, J. Acoust. Soc. Am. Suppl. 1 66, S81 (1979)] is here applied to the case of sound scattering from an absorbing bubble. The mechanical impedance of the scatterer is a meromorphic function of frequency, belonging to the class of Wigner's R functions [E. P. Wigner, Ann. Math. Stat. 53, 36 (1951)] which have poles on the real axis. Developing the S matrix (which contains the R functions) in the one-level approximation leads to a Breit-Wigner resonance formula with a frequency shift and a resonance width. The effect of absorption in the bubble consists in a further shift of the resonance frequency and a broadening of the resonance width. Both of these effects (in particular the broadening of the widths) are suitable means for determining the absorption, which is crucial for the echo reduction of a target. [H. Überall is also at Catholic University, Washington, DC 20064, additionally supported by Code 421 of ONR.]
Acoustic intensity measurement using a microphone tube
Authors: Schwind David R.
Published: October 2005

A technique is presented for use in industrial plants to measure acoustic intensity from individual machinery components in the presence of contaminating noise from other machinery. A microphone is placed inside a plexiglas tube; the open end of the tube is sealed to the machinery and the closed end contains an anechoic termination. The effect of microphone position on the amplitude response inside the tube has been examined. Four different procedures have been used to characterize the frequency response of the tube to different noise source radiation impedances. The sound intensity of a pump and motor were measured using the substitution method and the tube. Similarly, measurements made in the tube were compared with those made over a hemisphere around a thin panel source. A loudspeaker coupled to the tube was used to identify tube resonances. An FFT processor was used to find the tube's transfer function using a broadband thin-panel velocity source.
Generalized three-dimensional time dependent displacement wavefield description for arbitrary inhomogeneous, lossy media
Authors: Akers G. R.
Published: October 2005

The general nonlinear behavior for a one-dimensional wavefield solution has been established and through the use of convolution of one-dimensional solutions the general three-dimensional wavefield is obtained. Whereas in the case of the lossless modified homogeneous partial differential wave equation a product solution is obtainable by separation of variables, one may obtain by complex convolution of one-dimensional series solutions the total general solution for the nonhomogeneous lossy partial differential equation for three dimensions. This general three-dimensional solution describes the decay and distortion of the displacement field in the lossy, inhomogeneous medium, and the operation of the losses is seen in the nonlinear character of the solution. [Work supported by Navy Long Term Training Program.]
Echolocation and hearing in the mouse-tailed bat (Rhinopoma hardwickei)
Authors: Kick S. A. , Simmons J. A. , Lawrence B. D.
Published: October 2005

Rhinopoma produces four-harmonic, constant frequency orientation sounds. The 7- to 8-ms-long search and 2- to 4-ms-long approach signals rise to full amplitude in two to three waves of the fundamental (18 kHz), producing an onset transient. This click-CF signal appears unique to Rhinopoma and may link the complex orientation sounds of the Microchiroptera with the sonar clicks of shrews. The N4 audiogram shows sensitivity peaks corresponding to the harmonic peaks of the signal spectrum. Sensitivity is particularly great for the second harmonic, the strongest component of the signal. This sharp tuning around the second harmonic suggests that primary auditory neurons may have Q-10 dB values as high as 20 to 50. The sharp roll-off on the low frequency side of this sensitivity peak further suggests Rhinopoma may perform the Doppler-compensation response.
Response differences in gerbil and guinea pig auditory nerve fibers for low frequency sinusoidal acoustic stimuli
Authors: Oshima W. , Sokolich W. G. , Strelioff D.
Published: October 2005

Time locked responses of auditory nerve fibers to a 50-Hz sinusoidal acoustic stimulus were studied in both guinea pigs and gerbils. Whereas the time locked responses of all guinea pig fibers resulted in single peaked histograms, those of gerbil auditory nerve fibers resulted in either single, double, or triple peaked histograms. Generally speaking, single peaked histograms are associated with gerbil fibers having CFs below about 2 kHz, double peaked histograms with fibers having CFs between 2 kHz and 8 kHz, and triple peaked histograms with fibers having CFs above 8 kHz. Although the shapes of the histograms vary with stimulus level, the locations of the peaks of maximum response are essentially invariant over the range of stimulus intensities used. In guinea pigs, the relative latency of peak response increases progressively with increasing fiber CF. In gerbils, the same is true only for fibers having CFs below about 2 kHz. Accordingly, there does not appear to be a CF independent preferred time of occurrence of neural response relative to the acoustic stimulus in either species.
/s/ + stop clusters in the speech of ten language-delayed children
Authors: Bond Z. S.
Published: October 2005

In the acquisition of /s/ + stop clusters, before correct production, children commonly substitute one of the members for the entire cluster, the most common substitute being a stop at the appropriate point of articulation. Furthermore, there is tentative evidence that some children attempt to distinguish the stops substituting for clusters from voiced stops. The purpose of this investigation was to compare the acquisition of /s/ + stop clusters by language-delayed children to normal acquisition, first, in terms of phonemic substitutions and, second, in terms of differential use of VOT for the substituted stops. Ten children diagnosed as language-delayed served as subjects, C.A. 3;0 to 8;7; all used language below expectation for their chronological age. Each child recorded three tokens of near minimal triplets, beginning with a voiced stop, a voiceless stop and an /s/ + stop cluster, (e.g., Kate, gate, skate), for all three points of articulation, bilabial, alveolar, and velar in the course of identifying pictures. The children produced 95% of the intended clusters as singleton stops. VOT measurements for all stops were made from spectrograms. If the criterion for appropriate use of VOT to distinguish voiced from voiceless stops is taken to be +30 ms, then six of the ten children were producing voiceless and voiced stops appropriately over 80% of the time. For these children, 86% of the stops substituting for clusters were produced with VOT values in the long lag range. The other four children employed a unimodal VOT distribution for all types of stops, voiceless, voiced, and substituting for clusters. The data suggest that language delayed and normal children follow similar strategies in the acquisition of /s/ + stop clusters.
Computer-aided speech training in articulation therapy
Authors: Joost Michael G. , Petry Frederick E. , Olroyd Marie
Published: October 2005

The monitoring of responses and reinforcement of correct responses are time consuming aspects of traditional speech therapy. A microcomputer-based system has been developed which will relieve the therapist of much of the burden in repetitive practice sessions. It has been designed around commercially available systems which permit the recognition of isolated words or short phrases and utilizes a computer-aided instruction format in the patient practice sessions. A discriminant analysis approach is used for word recognition rather than the more common template comparison technique. Discriminant functions are formulated for each word to be used in the practice sessions based on the productions (classified satisfactory or unsatisfactory) of the target words elicited by a therapist in initial sessions. A pilot study has shown that this approach permits common phonemic developmental articulation errors, such as omission of an initial /s/, to be detected with very high reliability. Discriminant functions prove to be more efficient in both memory and speed than template matchings for the practice sessions and this is a major consideration in a cost effective system. This system should prove to be inexpensive enough to permit widely decentralized installation and is currently being considered for use in speech therapy services of a major city school system.
Arrays of random line arrays with constrained separations
Authors: Lockwood J. C. , Thorn J. V. , Booth N. O.
Published: October 2005

The statistical properties of beampatterns of random array s of line arrays are derived. The elements of each line array are distributed randomly with uniform probability density except for a restriction that no two elements are to be closer than a specified minimum separation. Except for this separation constraint, the array of line arrays presently considered has the same configuration as the partially random disk array described earlier [J. V. Thorn, N. O. Booth, and J. C. Lockwood, J. Acoust. Soc. Am. (to be published)]. The acoustic elements are arranged in vertical strings of M elements each. The array envelope is a disk of diameter D and thickness T, within which the strings are arranged at random horizontal positions. As in the partially random array studied previously, the ensemble average power pattern in the present case is characterized by a region of high average side-lobe power extending 360° in azimuth at the main-lobe elevation. The vertical separation constraint causes the high side-lobe region to be surrounded by a broad region of diminished average side-lobe power. Outside the latter region the average side-lobe power is constant. Calculated results presented show that the ensemble average directivity index, which in the unconstrained case is lower than for an array of individual elements, increases as a result of the separation constraint. Thus, the use of constrained separations represents a means of reducing the loss in random array directivity index that results from arranging the elements as an array of random line arrays. [Work supported by ONR.]
Generalized shading from a Taylor shaded line array
Authors: Miller Max K. , Lockhart Clayton M.
Published: October 2005

Because of the introduction of random access memory (RAM) into digital beamformer design, it is now possible to shade arrays so that the shading changes as the desired beam direction changes. For the simple case of a one-dimensional array [x,f(x)] we demonstrate a method of shading and give computer-simulated results. This method of shading is immediately applicable to two-dimensional arrays of the form [x,y,f(x)]. With this capability for shading we can analyze a restricted class of conformal arrays. [This work was supported by NAVSEA 63XT under contract N00024-79-C-6358.]
Free field rooms for industrial applications
Authors: Moreland J. B.
Published: October 2005

In order to develop a cost-effective design for a free field room having an overall shape of a rectangular parallele piped, we predict the acoustical field within such rooms by summing the contributions of the six primary images formed by the four walls, the ceiling, and the acoustically “hard” floor. Although the reflected energy in rooms of this type can be significant near the room boundaries, there generally exists a region around the source where sound pressure level measurements can be made that will be the same as those obtained with the source out-of-doors and resting on an acoustically hard surface. The performance of a free field room is, therefore, described in terms of the sound pressure levels that would exist out-of-doors. Because the constructive and destructive interference between the source and the image formed by the ground plane obscures the conformity of the sound field with the inverse square law, we have used a carousel method for evaluating the performance of free field rooms having “hard” floors.
Helmholtz air resonance of the cello and baritone
Authors: Hutchins Carleen M.
Published: October 2005

The so-called Helmholtz air resonance of the cello lies approximately an octave below its main wood resonance. This relationship causes the frequency range of the Helmholtz resonance to be extremely powerful because of second harmonic reinforcement when bowing. The original concept for the new violin family instruments (NVF) was to have these two main resonances in each instrument near the frequency of its two open middle strings, about a musical fifth apart. In designing the large cello, baritone of the NVF, it was found that musicians, accustomed to the power and tone quality of the cello's low C string range, liked the baritone when its Helmholtz resonance was more than the fifth below its main wood resonance. However, in the musical evaluation of the NVF at the Royal College of Music, London, the low C string range of the baritone seemed to overbalance the other instruments, particularly the higher ones. Therefore a baritone with shallower ribs was built with its Helmholtz resonance at 89 Hz and its main wood resonance at 157 Hz. Construction parameters and musical evaluation of these instruments will be discussed.
Effect of lubricants on ball bearing noise
Authors: Lalwani R. J.
Published: October 2005

Noise generated by ball bearings has been of considerable interest from various points of view. A noiseless ball bearing has become a necessity in many applications. Noise generated by ball bearings is very complex in nature and depends on a large number of parameters. Lubricant is one of these parameters. This paper deals with the experimental investigation carried out in a specially designed anechoic chamber to determine the effect of various types of lubricants on ball bearing noise. The lubricants used for the investigation include different grades of SAE oils, sodium-, lithium- and calcium-based greases. Noise spectrum obtained during the investigation indicate that due to inefficient and improper lubricants both the magnitude of noise levels as well as the characteristic frequencies are considerably changed. From the present investigation it is concluded that some lubricants behave very well in reducing the overall noise levels. Ball bearings running with sodium-based greases are found quieter than those with lithium and calcium-based greases. Therefore, it is suggested that proper lubricant is necessary for quiet running of ball bearings.
An effective noise diagnosis scheme for industrial plants
Authors: Elmaraghy R. , Baronet C. N.
Published: October 2005

This diagnosis is part of a comprehensive noise abatement program designed to provide an understanding of the overall noise problem in a plant before any controls are implemented subsequently. Field measurements are performed in order to generate the plant noise matrix defining the noise level at different working locations independently of the production rate prevailing on the day of the tests. Rank ordering of machine noise sources, noise reduction priorities, and magnitudes required in the plant are established based on the workers exposure indexes criteria. This scheme provides the required information to proceed in defining an optimum noise control protection plane, from an economical and technical standpoint in order to comply with the regulations. An actual application in a sawmill plant is discussed in this paper.
Neural response patterns for frequency.changing signals
Authors: Shore S. E. , Cullen J. K.
Published: October 2005

In previous studies, whole nerve AP's recorded from the guinea pig VIII nerve were shown to differ in response to 5-ms rising and falling frequency tone glides (Shore and Cullen, 1978). The rising glide resulted in larger N1 and N2 amplitudes. The present study examined AP's in response to 2-ms rising and falling glides with seven differing rates of frequency change. Waveform analysis indicates greater N1 and N2 amplitudes in response to the rising glides for rates of change up to 160 Hz/ms. At rates of change greater than 160 Hz/ms, amplitudes are larger for the falling glide. Later peaks show larger amplitudes for rising glides at all rates, suggesting convergence of neural input. These findings suggest that directional responses to frequency-changing signals reported for higher-order neurons are not solely a function of neuron type. Rather, differential coding is initiated at a cochlear level. [Work supported in part by NIH.]
Effects of glutamate and aspartate on tone-evoked and spontaneous activity in posterior ventral and dorsal cochlear nucleus
Authors: Caspary D. M.
Published: October 2005

As previously reported [Caspary and Havey, Neurosci. Absts. 5, 17 (1979)], iontophoretic application of the excitant amine acids, glutamate and aspartate, can affect thresholds and response patterns of cochlear nucleus (CN) neurons. This and recent data [Godfrey et al., J. Histochem. Cytochem. 25, 417 (1977); Wenthold, Brain Res. 143, 544 (1978); 162, 338 (1979)] support the hypothesis that glutamate and/or aspartate may be the neurotransmitter(s) at acoustic nerve endings. Control rate-intensity curves were obtained from neurons in the posterior ventral CN “on” and “chopper” responders) and dorsal CN (“pauser” and “build-up” responders). Rate-intensity curves shifted to the left with iontophoretic application of effective dose levels of glutamate and aspartate. Data plotted as percent increase (above control response) against intensity demonstrated that the largest changes occurred at near threshold intensities. “Chopper” neurons displayed increased non-tone-evoked activity at lower doses (2–150 hA) of excitant amino acids than “on,” “pauser,” and “build-up” neurons (100–250 nA). These data further demonstrate that glutamaro and aspartate can differentially affect CN neurons. [Supported by NIH and the Deafness Research Foundation.]
Neural generators of brainstem auditory-evoked responses
Authors: Britt Richard H. , Rossi Glenn T.
Published: October 2005

In a series of 55 pentobarbital anesthetized cats, discrete lesions (36 animals) and gross electrode recordings (28 animals) were made in the nuclei and tracts of the ascending auditory pathway. Ten per second clicks were presented monaurally, and the responses averaged from differential recordings between vertex and mastoid. Cochlear microphonic (CM) was monitored from round window electrodes. Five waves (I-V) were routinely recorded. Wave I matched the latency of N1 of the CM and remained, although significantly elongated in configuration, after complete aspiration of the cochlear nucleus (CN). If the CN were surgically isolated, or large lesions made of the ipsilateral superior olivary complex (SOC), all but waves I and II disappeared. Wave III was most affected by large lesions of either SOC. Activity with a latency of wave III was recorded from either SOC and, to a lesser extent, from the trapezoid body, the latter of which also had activity with a latency of wave II. Activity with a latency of wave IV was recorded in the region of the lateral lemniscus extending caudally to the SOC and rostrally to the inferior colliculus, but primarily in the dorsal nucleus of the LL. Activity compatible with wave V was seen only in either inferior colliculus. This work suggests that there are ipsilateral neural generators of waves I and II and multiple bilateral neural generators for waves III, IV, and V. [Work supported by VA RAG and Merit Review Grants and the Stanford Neurosurgery Research Fund.]
Detection of mixed modulation
Authors: Hartmann W. M. , Hnath G. M.
Published: October 2005

According to Goldstein's 1967 theory [J. Acoust. Soc. Am. 41, 458–479 (1967)] modulation is detected by the detection of energy fluctuations in a critical band filter centered on the lower modulation sideband. This theory predicts the relative detectabilities of AM and FM. We have generalized the theory to the detection of mixed modulation, MM, viz., combined AM and FM. The parameter space of MM is rich; AM and FM may be combined in any proportion and with any relative phase; the ratio of upper to lower sideband levels may take on any value. Therefore, MM experiments provide a stringent test of the general detection theory. In particular, as the upper sideband level is increased relative to the lower it becomes advantageous to the listener to change to a critical band filter centered on the upper sideband. The conditions for this transition can be predicted from pure tone masking data. We performed parallel AM, FM, MM, and masking experiments. Although most data support the theory, thresholds at the transitions are anomalously high in some conditions in disagreement with theory. [Supported by the NSF.]
Phase sensitivity of human frequency-following response to the “missing fundamental.”
Authors: Greenberg Steven , Marsh James T.
Published: October 2005

The pitch of a harmonic signal is not appreciably changed upon alteration of the component phase configuration for tones of low harmonic rank (<harmonic 8) (Bilsen, 1973). This implies that the “central pitch processor” is insensitive to the relative phase of the signal's frequency components. Farfield, vertex-derived, frequency-following responses (FFR) (representing the integrated activity of phase-sensitive neurons of the upper brainstem pathway) were recorded during presentation of three-component (F1 = 732 Hz, F2 = 976 Hz, F3 = 1220 Hz) tone bursts of variable phase configuration. For each series, stimuli were identical in all respects except for the starting phase of F2. F1 and F3 always began in sine phase. The starting phase of F2 varied from 0° to 180° in 45° steps. FFR amplitude at the fundamental frequency (244 Hz) (as determined by spectral analysis) varies as a function of phase configuration when all three frequency components are of equal intensity. However, when the level of F2 is 6 dB above F1 and F3, FFR amplitude is unaffected by changes in stimulus phase configuration. These results suggest that FFR to the “missing fundamental” is determined principally by the frequency and relative amplitude of the stimulus harmonics rather than by characteristics of the aggregate stimulus waveform (such as envelope modulation pattern).
Using acoustic data to improve estimates of the mapping from saggital dimensions to area functions
Authors: Wright J. T.
Published: October 2005

Formant frequency data was used to adjust estimates of 18 cross-sectional areas of the vocal tract produced by a conversion function relating midsaggital dimensions in lateral x rays to direct physiological measurements of vocal tract area [P. Ladefoged, J. Anthony, and C. Riley, UCLA Working Papers in Phonetics 19, 4–13 (1971)]. The logarithm of the estimated area function was described by Fourier coefficients and bandlimited by preserving 2n components. The odd-numbered Fourier coefficients were adjusted until a match was achieved between the measured formant frequencies and the admittance poles for the estimated area function. The even coefficients retained their original values thereby providing a unique determination of the area function constrained by the original estimate of tract shape. Fifty sets of estimates based on the midsaggital dimensions of ten American English vowels spoken by five speakers, and their corresponding formant frequencies, aided in the construction of an improved conversion function mapping midsaggital distances to cross-sectional areas for the vocal tract. [Work supported by NIH.]
Spatial distribution of very low-frequency wind-generated noise in the ocean
Authors: Ingenito F. , Kuperman W. A.
Published: October 2005

We have adapted our model of surface-generated noise in a stratified lossy ocean to the case of low-frequency wind-generated noise produced in deep water by turbulent pressure fluctuations in the atmosphere. The model assumes a random pressure distribution at the surface and includes the effects of sound-speed profile and bottom characteristics. Using Wilson's source levels [J. H. Wilson, J. Acoust. Soc. Am. 66, 1499–1507 (1979)] we have calculated the noise level as functions of frequency and depth and compared the results with measured data. We show these results along with calculations of the spatial coherence function, which differs significantly from the standard deep-water result. Finally, we present calculations of the effective surface area, that is, the area of the surface centered above the receiver which contributes most of the noise intensity. We show that this quantity is dependent on receiver depth.
Characteristics of low-frequency propeller noise generated by merchant vessels
Authors: Gray Leslie M.
Published: October 2005

Noise radiated by propeller cavitation on merchant vessels is a major contributor to ocean ambient noise in the 2 to 100 Hz frequency regime. This cavitation generates discrete lines at propeller shaft and blade rates and harmonics. In order to understand this acoustic source, an analytical model has been developed to predict the cavitation volume—time histories on a given propeller. This paper reviews this model development, outlining the physical basis for the model, and the acoustic radiation characteristics of this source. The model is exercised for an example merchant vessel. Results are presented showing the variation of the source strength of the propeller-generated lines with ship speed, wind and sea state, vessel ballast condition, propeller design, and hull form variables. It is demonstrated that the propeller source strength is strongly dependent on the vessel design, and on operational characteristics.