bluuebunny/crossref_metadata_2025 huggingface dataset:
A tympanometric evaluation of middle-ear development in neonatal hamsters
Authors: Relkin E. M. , Saunders J. C. , Konkle D. F.
Published: October 2005

Tympanometry was used to follow the maturation of middle-ear function in neonatal hamsters from 6 to 80 days of age. Subjects in each of seven age groups were anesthetized, mounted in a head holder, and the tympanic ring and auditory bulla were exposed surgically. The bulla was ventilated with small bore nylon tubing in order to equalize middle-ear pressure to ambient pressure. A tympanometer probe was sealed directly over the tympanic membrane using a short piece of rubber tubing to couple the probe to the tympanic ring. The magnitude of relative acoustic impedance was measured at frequencies between 1.0 and 1.5 kHz. Relative acoustic impedance was the difference between the impedance measured when the tympanic membrane was stressed with a pressure of +200 mm H2O and the minimum impedance that could be obtained as the pressure was reduced. There was no measurable impedance magnitude difference on day six, but by day 15 small though reliable values could be obtained. Thereafter, impedance magnitude changed rapidly and reached a plateau after 33 days. No further changes were noted in 77-day-old animals which were considered to be adults. Results will be discussed with regard to the maturation of middle-ear morphology and inner-ear physiology. [Supported in part by the NSF and the Deafness Research Foundation.]
The tectorial membrane may sharpen the cochlear frequency selectivity
Authors: Zwislocki J. J. , Kletsky E. J.
Published: October 2005

Radial shearing motion between the tectorial membrane and the reticular lamina is generally held responsible for the excitation of the hair cells. However, the shearing motion must depend on the coupling between the tectorial membrane and the organ of Corti. A sufficiently tight coupling would effectively prevent it. Motion of one part of the tectorial membrane must also depend on the motion of the adjacent parts because of a longitudinal coupling within the membrane. When the membrane is driven by the organ of Corti in the same direction over a substantial length, it should be entrained more than when neighboring sections are driven in opposite directions. Consequently, the shear relative to the reticular lamina should be minimized where the cochlear waves are long and maximized where they are short. Since the wavelength is the smallest near the vibration maximum, the shear should be the greatest there. A computer simulation shows that such a mechanism can account for the difference between the known neural and basilar membrane tuning curves. [Work supported by NIH.]
Psychoacoustical tuning curves and narrow-band masking in normal and impaired hearing
Authors: Florentine Mary
Published: October 2005

Psychoacoustical tuning curves and narrow-band masking were measured in normal and groups of moderately hearing-impaired observers (conductive, otosclerosis, noise-induced, and degenerative). The SPL of pure tones needed to just mask an intermittent 4-kHz tone at 10 dB SL was measured as a function of the masker's frequency. Results support Schorn, Wurzer, Zollner, and Zwicker [Laryngol. Rhinol. 56, 121 –127 (1977)] and show wider tuning curves for the noise-induced and degenerative groups than for the other groups. In the same observers, thresholds for 600-ms pure tones were measured as a function of frequency in the presence and absence of a continuous 40-dB-SL narrow-band noise centered at 4 kHz. Results show an enlarged upward spread of masking only for the noise induced and degenerative groups. However, at equal SPL the differences between observers with normal hearing and those with cochlear impairment were considerably reduced. [Work supported by Rotary Foundation and Deutsche Forshungsgemeinschaft through Sonderforschungsbereich 50 “Kybernetik,” Munchen.]
An articulatory synthesizer for perceptual research
Authors: Rubin Philip , Baer Thomas
Published: October 2005

A software articulatory synthesizer, based upon a model developed by Mermelstein [J. Acoust. Soc. Am. 53, 1070–1082 (1973)], has been implemented at Haskins Laboratories. The synthesizer is being used as a tool for studying the linguistically and perceptually significant aspects of articulatory events. A prominent feature of this system is that it easily permits modification of a limited set of key parameters that control the positions of the major articulators: the lips, jaw, tongue body, tongue tip, velum, and hyoid bone. Time-varying control over vocal-tract shape and nasal coupling is possible by a straightforward procedure that is similar to keyframe animation: Critical vocal tract configurations are specified, along with excitation and timing information. Articulation then proceeds along a directed path between these key frames within the time script specified by the user. Such a procedure permits the required degree of control over articulator positions and movements. The organization of this system and its present and future applications will be discussed. [Work supported by NSF Grant BNS-7682023.]
The perception of oral-nasal continua generated by articulatory Synthesis
Authors: Abramson A. S. , Nye P. W. , Henderson J.
Published: October 2005

A growing body of evidence suggests that speech perception is intrinsically related to the mechanism of production. By means of an articulatory synthesizer described in another paper, the perception of the oral-nasal distinction was explored experimentally. It was chosen because it is achieved by a very simple articulatory maneuver and it is phonologically relevant in virtually every language. The effect of variation in the size of the velo-pharyngeal port on the perception of oral versus nasal consonants was tested. Two stimulus continua varying in size of velo-pharyngeal opening were synthesized, one with equal increments of port area and the other with equal increments of velar lowering, ranging from full closure for an English /da/to a large enough opening for an unambiguous /na/. These two syllables formed the end-points for the two continua, each of which contained nine variants. Native speakers of English were instructed to label randomized presentations of the two continua as either /da/ or /na/. The subjects were also given AXB discrimination tests. The relations between categorization and discrimination data for each of the two continua will be discussed. [Work supported by NSF Grant BNS-7682023.]
Some relationships between articulation and perception
Authors: Raphael L. J. , Bell-Berti F. , Pisoni D. B. , Sawusch J. R.
Published: October 2005

EMG studies of the American English vowel pairs /i-ɪ/ and /e-ε/ reveal two different production strategies: some speakers appear to differentiate the members of each pair primarily on the basis of tongue height; for others the basis of differentiation appears to be tongue tension. To determine if these production differences correspond to perception differences, two vowel identification tests were given to the EMG subjects. Subjects were asked to label the members of a seven-step vowel continuum, /i/ through /ɪ/. In one test each item had an equal probability of occurrence. The other was an anchoring test: the first stimulus, /i/, was heard four times as often as any other. Compared with the equal-probability test labelling boundary, the boundary in the unequal-probability test was displaced toward the anchor stimulus. However, the magnitude of the shift was greater for subjects using a production strategy based on tongue height than for subjects using tongue tension to differentiate the vowels. [This work was supported by NIH Grants NS-13617, NS-05332, HD-01994, and RR-05596 to Haskins Laboratories; and SUNY Research Foundation.]
Fluctuations in vertical angle of arrival caused by the surface reflection
Authors: Urick R. J.
Published: October 2005

It is well known that a transducer split into its right and left halves can determine the bearing of a target with a high degree of accuracy. However, in the vertical plane, the vertical angle of arrival as found by phase comparison of its upper and lower halves is found to fluctuate wildly so as to prevent an accurate determination of target depth. To explain this, one would at once suspect interference by the surface reflection. That such was indeed the case has been demonstrated by a field experiment, in which the magnitude of the observed fluctuation was found to agree with theoretical expectations based on the depression angle and beam pattern of the split transducer. Photographs of short 25-kHz pulses showed that the sea surface acted as a reflector for a near-surface receiver, even though the Rayleigh parameter (equal to the product of the acoustic wave number, the rms surface wave height and the sine of the grazing angle) was appreciably greater than unity and so indicated an acoustically rough, rather than an acoustically smooth, surface.
Distributed aperture model of the nearfield of a parametric sonar
Authors: Lockwood James C.
Published: October 2005

That difference frequency sound levels measured close to a parametric source can not be readily extrapolated to farfield levels is by now well known. A number of theoretical treatments for predicting nearfield levels have been advanced and all are in substantial agreement. The treatment now presented, which applies to parametric sonars with circular projectors, is of particular interest because it lends itself to extension to rectangular projectors of arbitrary aspect ratio. In addition, the method leads to an algorithm for predicting axial levels that includes both finite-amplitude and nearfield affects, and is implementable on a programmable, hand-held calculator. The algorithm is based on the farfield parametric radiator model of Moffett and Mellon [J. Acoust, Soc. Am. 61, 325–337 (1977)]. The distributed aperture approach is used to derive factors that correct the farfield model for significant variations in the source to field-point distance within the parametric array nearfield. The present paper presents the derivation of the algorithms for axial levels and for nearfield beam patterns for a circular parametric projector. Experimental data supporting the theory are also presented. The extension to the rectangular projector is the subject of a companion paper by R. G. Pridham also in this session. [Work supported in substantial part by Defense Advanced Research Projects Agency under Contract N00024-74-C-1151 at AMETEK, STRAZA Division.]
Syllable timing and vowel perception
Authors: Verbrugge R. R. , Isenberg D.
Published: October 2005

Consonantal environment may aid in specifying vowel identity by supplying critical information about timing. Several vowel pairs in American English are distinguished by temporal as well as spectral variables, and these temporal differentia vary with articulatory rate. Two studies were designed to explore the following paradox: When consonantal formant transitions are introduced into a steady-state vowel, holding syllable duration constant, a response shift is observed toward longer-vowel alternatives, even though steady-state duration has been reduced. The first study verified this finding for the vowel pair /ε/-/æ/ in comparisons of ♯V♯ and bVb continua. Pairs of continua were defined separately by F1 variation and by duration variation, and each continuum type evidenced the paradox. A second study varied the rate of symmetric consonantal transitions in F1-varying CVC continua (V = /ε, æ/, C = ♯, b, w/) in order to test whether transition rate might specify an articulatory rate that effectively scales vowel duration. Vowel responses did not vary monotonically with either transition rate or steady-state duration, but interacted with the perceived identity of the initial consonant. Listeners' judgments may demonstrate a sensitivity to constraints on the relative timing of consonantal and vocalic gestures. [This work was supported by NIH grant HD-01994 to Haskins Laboratories, and by the University of Michigan Society of Fellows.]
Pitch-matching of tone glides with a pure-tone cursor
Authors: Whittaker R. G.
Published: October 2005

To determine the pure tone equivalent of tone-glide stimuli, a pitch-matching task was designed wherein a pure tone cursor was used to match the pitch of either pure tone or gliding test stimuli. No significant differences were found between ears, however a dramatic difference was noted between performance to glides which increased frequency over time (upglides), and those that decreased frequency over time (downglides). Upglides, particularly those that changed frequency by 40–80 Hz over the 100-ms duration, were matched by a pure tone frequency higher than any present in the stimulus; that is, subjects tended to overestimate upsweeps. Furthermore, the amount of overestimation was a nearly-linear function of the amount of frequency change present in the signal. A completely different response pattern was seen when down-glides were matched. Pitch estimates of downglides fell at or near the glide midpoint, regardless of the amount of frequency change present in the stimulus; that is, downglides seemed to be averaged. This differential responding based upon the direction of frequency change has been reported by other observers, but remains unexplained.
Ear dominance in the perception of conflicting pitch sequences
Authors: Gregory Andrew H.
Published: October 2005

Subjects were presented with a sequence of two tones differing in frequency in one ear, and at the same time a sequence of another two tones in the other ear. A low-high frequency sequence in one ear was always presented with a high-low sequence in the other ear, and the subject was asked to report which pitch sequence he heard. If the frequency difference was the same in each ear (e.g., 1650 Hz–1750 Hz in one ear and 1750 Hz–1650 Hz in the other), then subjects always reported the sequence in one particular ear, which was defined as their dominant ear. If the frequency difference in the dominant ear was progressively reduced (e.g., 1690 Hz–1710 Hz in the dominant ear and 1750 Hz-1650 Hz in the other), a point was reached where subjects changed over to reporting the pitch sequence in their nondominant ear. This change was very sensitive to changes in the frequency difference, but very insensitive to intensity differences between the two ears. These results are discussed in relation to experiments on ear dominance in the perception of dichotic chords [R. Efron and E. W. Yund, J. Acoust. Soc. Am. 59, 889–898 (1976)].
Cross-modality temporal resolution for auditory, vibrotactile, and visual stimuli
Authors: Sinex D. G.
Published: October 2005

Cross-modality temporal resolution was measured using a procedure in which subjects adjusted the temporal asynchrony ΔT between a pair of stimuli to match that of a standard pair. The stimulus pairs were click-tap, click-flash, or tap-flash with values of ΔT betweel 0 and ± 120 ms. Also, judgments were obtained for within-modality stimulus pairs. The results indicate more precise temporal resolution (e.g., more reliable judgments) for click-tap pairs than for either click-flash or tap-flash pairs. Matches made using click-tap pairs are also more accurate (e.g., have smaller constant errors). Within-modality stimulus pairs are resolved more precisely than cross-modality pairs. However, the poorest within-modality resolution, found for flash-flash pairs, approaches that seen for click-tap pairs. These results are compared to the findings of Hirsh and Sherrick [J. Exp. Psychol. 61, 423–432 (1961)], who reported that the precision of order labeling is nearly invariant for various within-modality and cross-modality stimulus conditions.
Adaptation effects in binaural experiments
Authors: Moss Peter J. , Colburn H. S.
Published: October 2005

Experiments were conducted to examine some of the effects of imbalanced interaural parameters on binaural lateralization. We examined adaptation both to stimuli with interaural amplitude differences and to stimuli with interaural time differences. To measure the adaptation over time, 30-trial runs were made with each run lasting about 15 min. On each trial, the subject was required to adjust the interaural time delay from an initial random value to a value that resulted in a centered image. For a low-pass filtered pulse train with an interaural amplitude difference of 10 dB, the amount of interaural time delay needed to center the image changed from 250 μs at the outset to 100 μsec at the end of the run. These results are consistent with earlier results using a paradigm nearly identical to ours [M. P. Bertrand, Proc. R. Soc. Med. 65, 3–4 (Sept. 1972)]. For the same low-pass filtered pulse train with no interaural amplitude differences, but with the initial random delay restricted to one ear, the amount of time delay needed to center the image changed by as much as 50 μs during the course of a run, i.e., at the end of a run the subjects no longer heard a diotic presentation (zero delay) in the center of their heads. Two possible mechanisms of adaptation will be discussed. [Work supported by NIH.]
Cue-reversal points and interaural time JND's at various frequencies
Authors: Moss P. J. , Mills A. W. , Colburn H. S.
Published: October 2005

Previous research on the lateralization of a 500-Hz tone as a function of interaural delay T has suggested that there exists a delay T0 (usually in the vicinity of 700 μs) that divides the interval 0 ⩽ T ⩽ 1 ms into two regions: the region 0 ⩽ T ⩽ T0, where an incremental increase in T causes the binaural image to move farther to the side, and the region T0 ⩽ T ⩽ 1 msec where an incremental increase in T causes the image to move back towards the center [Hershkowitz and Durlach, J. Acoust. Soc. Am. 46, 1464–1467 ( 1969)]. This critical delay To is referred to as the “cue-reversal” point. We are conducting experiments employing 21, 2AFC procedures and acoustic monitoring to explore the dependence of cue-reversal points on frequency f. In these experiments, no feedback is given and the subjects are required to judge whether the addition of an increment ΔT to T causes the image to move toward or away from center. Preliminary results indicate that (1) the values of T0 on the right and left are often unequal and (2) the cue-reversal phenomenon is incomplete in the sense that lateralization performance in the region T0⩽T⩽12f is less consistent than performance in the region 0 ⩽ T ⩽ T0. We also plan to investigate, using a similar paradigm with feedback, interaural time jnd's in the vicinity of the cue-reversal point. [Work supported by NIH.]
In search of optimum electroacoustic characteristics of hearing aids
Authors: Collins M. J. , Levitt H. , Freeman L. R. , Barth C.
Published: October 2005

An adaptive procedure was used to select the optimum setting on a wearable master hearing aid for discrimination of nonsense syllables. All subjects were experienced hearing-aid users with a variety of hearing impairments. Discrimination was measured at the estimated setting and with the subject's own aid. Additionally, functional gain using narrow bands of noise was determined with the wearable master hearing aid and the subject's own aid. An analysis was performed relating improvement in discrimination scores to the differences in the functional gain, and to additional factors of comfort level, dynamic range and long term speech spectrum. [Work supported by NINDS contract No. NIH-ND1-NS-4-2323.]
Effects of alcohol on the latency of the acoustic reflex
Authors: Brey Robert H. , Robinette Martin S.
Published: October 2005

A comparative study was conducted on the relative latency of the acoustic reflex in alcoholic vs. nonalcoholic test sessions on seven normal hearing adults. Acoustic reflex data were collected using impedance audiometry. Reflex eliciting stimuli were a 500-Hz pure tone, and a low frequency band of Noise 500–1000-Hz wide. The parameters analyzed were defined as: (1) L1, the onset of the signal to the initiation of the reflex, (2) L2 the initiation of the reflex to 90% of the maximum amplitude, (3) L3, the offset of the signal to the initiation of the reflex decay, and (4) L4, the initiation of the reflex decay to 10% of the maximum amplitude. Alcohol levels were monitored using a breath-analyzer test. Results showed that overall, alcohol had little effect on the L1 and L3 durations, whereas, the L2 and L4 latencies were longer in the alcohol than in the nonalcohol condition. There was a definite trend toward increased variability among the subjects for all responses under the alcohol condition when compared to the nonalcohol condition. [Work supported by NIH.]
Study of the cochlear after-potential: preliminary report
Authors: Durrant J. D.
Published: October 2005

The cochlear after-potential was originally suggested as a sequel to the neural activity elicited during the sound stimulus. To learn more about this little-known response, the influence of the temporal aspects of the stimulus on the after-potential were investigated in the guinea pig cochlea utilizing intracochlear electrodes in the first turn. The magnitude of the (positive) afterpotential was found to decrease with increased decay times of the tone-burst stimulus (usually 12 kHz at 70 dB SPL). However, except for very abrupt turnoffs, usually ⩽1 ms, the effects of decay time were not substantial. Particularly striking was the observation that regardless of decay time the peak of the after-potential always occurs at about the point in time at which the sound is completely turned off. The peak magnitude of the (positive) afterpotential was also not substantially influenced by the duration of the tone burst, but the slow negative deflection, which often appeared after the initial positive component, was found to increase with increasing duration. Finally, the after-potential was found to behave differently than the whole-nerve action potential on several counts, i.e., in terms of the influence of rise-decay time, which suggests some degree of independence between the two responses. [Work was supported by DRF.]
Diplacusis and the pitch of the cubic difference tone
Authors: Burns E. M.
Published: October 2005

Extensive monaural and binaural pure tone pitch matches to the cubic difference tone (CDT) 2f2−f2 were obtained for various CDT frequencies, with several primary tone (f1, f2) frequency Configurations for each CDT frequency. Two types of conditions were of special interest: (1) those for which moderate diplacusis existed at the frequency of the CDT but negligible diplacusis existed at the frequencies of the primary tones; and (2) those for which negligible diplacusis was present at the CDT frequency but moderate diplacusis existed at one or both of the primary tone frequencies. The results are discussed in regard to assumptions concerning the origin of monaural and binaural pitch anomalies (musical paracusis, binaural diplacusis) and in regard to the question of whether the CDT is coupled back to the basilar membrane at the characteristic place of the CDT frequency.
Detection of tones in band-reject noise
Authors: Margolis R. H. , Popelka G. R.
Published: October 2005

Detectability of long duration (0.5 s) tonal stimuli in the presence of band-reject noise was measured as a function of the width of the spectral notch centered on the tonal signal. Results were nearly identical at three signal frequencies (fs = 0.5, 1.0, and 2.0 kHz). When the notch width is small (NW ≈ 0.03 fs) detectability is the same as in the zero notch-width control condition. When the notch width is increased to 0.1 fs, detectability decreases. For wide notch widths (NW ≈ 0.2 fs) detectability approaches errorless performance. In a second experiment, psychometric functions were determined for four notch conditions: NW ≈ 0, 0.03 fs, 0.08 fs, and 0.2 fs. Differences in the slopes of the psychometric functions resulted in level-dependent differences in detectability in the various notch conditions.
More on temporal compensation
Authors: Ellis S. M. , Weismer G.
Published: October 2005

Ohala and Lyberg [J. Acoust. Soc. Am. 59, 990–992 (1976)] have suggested that the often observed inverse relationship between the durations of adjacent segments in speech production may not reflect a true organizational process. Rather, Ohala and Lyberg argue that the inverse relationship may be a measurement artifact resulting from the fact that the adjacent segments share a measurement boundary, and that any error in the placement of this boundary “forces” an inverse relationship between the segment durations. Because the notion of temporal compensation may have utility in a model of speech production, we decided to perform a simple test in an attempt to separate the systematic influence of measurement error from any “true” covariance that might exist for the durations of adjacent segments. A single speaker recorded the utterance To catch a fish is to hook it [Wright, J. Acoust. Soc. Am. 56, 1258–1265 (1974)] one hundred times; two complete sets of spectrograms were subsequently prepared so that one set could be measured with a simultaneous boundary placement for adjacent segments, whereas the other set allowed independent placement of all segment boundaries. Results suggest that Ohala and Lyberg overestimate the influence of measurement error on measures of temporal compensation.
The patterns of syllable duration in English
Authors: Nakatani Lloyd H. , Dukes Kathleen D. , Aston Carletta H.
Published: October 2005

We report here some preliminary results from a large study of English speech rhythm. Adjective-noun phrases with three, four and five syllables (e.g., “bold design,” “poor bystander,” “electronic gear”) were spoken in meaningful sentences with the syllable “ma” substituted for each syllable of the phrase: for example, “bold design” was spoken as “MA maMA.“ The following aspects of the phrases were varied: (a) number of syllables, (b) stress pattern, (c) position of word boundary within the phrases, and (d) position of phrases within sentences. Preliminary results from three of eight talkers show how these variables influenced the “ma” syllable durations. The implications of the results for models of English speech rhythm, especially with regard to isochrony, will be discussed. The validity of the reiterant nonsense speech technique will also be discussed.
Perceiving the stress pattern of words in sentences
Authors: Nakatani Lloyd H. , Aston Carletta H.
Published: October 2005

The cues for hearing the stress pattern of a word may be different depending on whether the word occurs in isolation or in a sentence. Furthermore, even within a sentence, the relative importance of the cues depends upon where the word occurs in the sentence, and upon phrasal accent. For example, contrary to Fry's classic results with words in isolation, the pitch contour was useless as a cue for perceiving the stress pattern of a noun preceded by an accented adjective. The word's duration pattern proved a more robust cue than pitch for stress pattern perception; the word's amplitude contour was useless as a cue. These results derive from an experiment where listeners had to identify the stress pattern of bisyllabic nonsense words embedded in meaningful sentences. The listeners had only to choose between the nonsense words “MAma” and “maMA” (10 and 01 stress patterns, respectively) on the basis of the perceived stress pattern. The duration, fundamental frequency, amplitude and spectral features of the nonsense words were manipulated factorially via LPC analysis-synthesis to assess the relative importance of these acoustic features as cues for stress perception.
A cross-linguistic study on the perception of stress
Authors: Berinstein Ava
Published: October 2005

This study is an attempt to investigate the extent to which speakers of languages with inherently different stress assignment rules use duration to discriminate a stressed syllable from a sequence of syllables. Listeners representing three language groups with different stress patterns; English (variable), Spanish (penultimate) and K'ekchi (fixed final) listened to sequences of four synthetic CV syllables. In each sequence three of the four syllables were of equal duration (100 ms), while the duration of the remaining syllable varied between 70 and 200 ms. Subjects were asked to determine which of the four syllables in the sequence was stressed. It was found that the subjects' responses showed a bias in favor of a particular position and that the bias differed systematically across languages—English showed an initial bias; Spanish, no bias; and K'ekchi, a final bias. It is suggested that the response bias pattern for the three groups is in part governed by the linguistic structure and the stress assignment rules in a particular language. [Work supported by NIH.]
Acoustic-phonetic features of stressed syllables in the speech of three year olds
Authors: Hawkins Sarah , Allen George
Published: October 2005

Six middle-class children aged 3 years ± 4 months, were recorded talking with their caretakers on two occasions two weeks apart. From each session, phonetic transcriptions were made of 50 phonological phrases of two words or more in which a nuclear syllable (NS) could be identified. The phonetic features of the NS were classified in terms of pitch, length, loudness, and other categories (e.g., diphthongization, syllable doubling) developed during similar previous studies. Fundamental frequency (peak and shape), duration, and amplitude of both NS's and pre- and post-nuclear stressed syllables were measured oscillographically and spectrographically and compared with the impressionistic transcriptions. Comparisons were made between phrase-final vs nonfinal NS, and between nuclear vs non-nuclear stressed syllables. Preliminary data indicate that, although individual children vary in their pattern of use of features marking the NS, greater duration is most common phrase-finally, and change in f0, usually upwards, often accompanied by greater duration and/or intensity, is most frequent non-finally. These patterns are in general agreement with both the acoustic phonetics of adult English as well as more general psychophysical laws. [Supported by NSF.]
Variation in the duration of words
Authors: Keating Patricia , Kubaska Cathy
Published: October 2005

The acquisition of prosodic features by normal infants and children whose ages range from 10 days to 312 years is currently being investigated. In this report we will present data on the duration of single- and multisyllable words produced by a child who was tape recorded from 66 to 147 weeks of age. This sample consists of productions of utterances ranging from early words through complete sentences containing up to nine syllables. Preliminary results indicate a high variability in the duration of one of the more frequent words produced by this child in the period from 66 to 106 weeks. The mean duration of “doggie” from 71 to 73 weeks was 675 ms with a S.D. of 125 ms, and from 94 to 96 weeks it was 460 ms with a S.D. of 75 ms (t=5.19, p < 0.001). Measurements for a variety of words over a greater time span will be presented. The interaction of duration with the number of syllables, the stress pattern, and the f0 of the utterance will be discussed. [Work supported by NICHMD grant HD09 197-03.]
Developmental changes in the capacity to discriminate unfamiliar voices
Authors: Mann Virginia A. , Diamond Rhea , Carey Susan
Published: October 2005

Forced-choice discrimination of unfamiliar adult female voices has been examined in children age six to sixteen and in adults. Performance changed markedly with age, improving sharply between ages six and ten, with ten-year-olds approaching adult levels. After age ten accuracy declined significantly but returned to the adult level by age fourteen. These observations are not consistent with a previous suggestion that only a minimal change in voice recognition capacity occurs after age four [B. Bartholomeus, Canad. J. Psych. 27, 464–472 (1963)]. However, Bartholomeus' suggestion was based on observations of children's capacity to identify familiar voices. Apparently, tasks which require encoding of unfamiliar voices produce a developmental pattern distinct from that found in tasks requiring recognition of voices already represented in memory. This distinction parallels one recently documented between development of the ability to encode and recognize unfamiliar faces and development of the ability to recognize familiar ones [R. Diamond and S. Carey, J. Exp. Child Psychol. 23, 1–22 (1977)]. [Work supported by NSF, NIH, and the Spencer Foundation.]
Strings, ambiences and analyzers
Authors: Corliss E. L. R. , Breckenridge F. R. , Burnett Edwin D.
Published: October 2005

Performances by the Juilliard String Quartet visiting the National Bureau of Standards were recorded as played on two sets of instruments, under three different environmental conditions. The basic instruments were those ordinarily played by the concert artists in performance. A second set of instruments, made to duplicate the contours and size of the Stradivarius instruments played at the Library of Congress, were built by Martin Cornelissen, using classical procedures. Recordings were made also through the “eardrums” of a dummy simulating a median human listener. Using analyzers of several different designs, observations were made on the spectral and transient characteristics of these instruments, and upon several others including instruments made by Carleen Hutchins. Despite the confused echoes in the reverberation room, it did not affect the players' intonations significantly. The anechoic chamber was characterized by the players as “very intimate” but permitted study of the decays of individual notes on the instruments, both as bowed and plucked. In an auditorium basically designed for speech, instrument resonances were not strongly affected. Recordings made through the dummy demonstrate the spectral shaping introduced by the ears and ear canal. Effects will be demonstrated via recordings.
On the motion of the bowed violin string
Authors: Lawergren Bo
Published: October 2005

Oscillations with nodes at the bow point have been observed. For a typical violin string such oscillations exist for β > 0.08 (here β is the relative bow position along the string). For β > 0.18 the amplitude of this motion may become comparable to the Helmholtz motion if the bow force exceeds a critical value (2–40 g/wt. depending on the value of β). At the critical force and with β ≠ n−1 (n = 2, 3, 4...), the waveform can be well described analytically. The analytic expression consists of two terms, a sinusoid and the usual Helmholtz expression. It is used to calculate consecutive string shapes. At the critical bow force, the slip period of the string at the bow point is observably reduced to half the value given by the classical Helmholtz theory. However, this slip duration is given by the analytic expression. For bow forces much larger than the critical value the sinusoids of the waveforms (including the slip duration at the bow point) become narrower than the “predictions.” It is shown that this type of motion does not exist for β < 0.18 because it demands too high a bow force. The relationship between this motion and Raman's “higher types of motion” will be explained.
Prediction of acoustic wave angles resulting from the interaction of large eddies in unstable jet shear layers
Authors: Hall Sydney-Lynn
Published: October 2005

Good quality optical photographs of supersonic free jets show three principal types of acoustic waves: (1) nozzle-centered radiation in the form of high-frequency, closely spaced waves which steepen with distance away from the jet; (2) wider-spaced high-frequency waves emanating from the first six diameters from the exit and inclined at approximately the same angle as the initial nozzle-centered waves, but with little steepening; and (3) low-angled low-frequency waves which originate from the end of the potential jet core and are cut off at the end of the sonic core. A theoretical method developed for ideally-expanded air jets [C. K. W. Tam, J. Fluid Mech. 51, 69–95 (1972)] has been modified for refraction effects due to different density and sound speed jets exhausting into the quiescent atmosphere. The predicted acoustic wave angles are within 3° of the measured angles for six correctly expanded air and helium jets; the additional ‘shock’ noise contribution for thirteen helium and air jets operating in the 50 → 150% expansion range are underestimated by 3°–8° . The predicted angle for the low-frequency radiation is within three degrees of the “cone-of-silence” angle in the 15 cases where the acoustic cutoff is inside the optical field of view.
A Computer Model to Study Sound Propagation in Suburban Environments
Authors: Busch-Vishniac Ilene , Lyon Richard H.
Published: October 2005

A computer model has been developed to study sound propagation in suburban areas. The stimulation includes reflection, absorption, scattering, and transmission of sound at scattering surfaces as well as air absorption and predicts sound pressure levels at receivers as a function of time. Results from the computer model have been compared to scale model experiments, theoretical calculations, and field data with good agreement both in sound pressure level peaks and the time of their occurrence. The stimulation has been applied to a study of the role of multipath propagation in suburban areas.
Outdoor measurements of acoustic impedance
Authors: Willshire W. L. , Maestrello L.
Published: October 2005

Knowledge of the actual values of acoustic ground impedance is important to the understanding of and the ability to predict atmospheric propagation near the earth's surface; such propagation is involved in aircraft flyover and community noise problems. The acoustic impedance of concrete is being measured as a function of frequency using a normal incidence, interference pattern method. A unique aspect of the experimental apparatus is that it was designed to minimize the effects of scatter and spurious reflections on the measured interference pattern. The amplitude of the first maximum, the second maximum, and the distance above the ground of the first minimum of the interference pattern are used in an analytical model [based on P. J. Dickinson and P. E. Doak, J. Sound and Vib. 13, 309–322 0970)] to derive the complex acoustic impedance of a particular surface at a particular frequency. The acoustic impedance of concrete for a few discrete frequencies has been measured and will be presented; future plans include continuing the work with concrete and the measurement using a similar method of the acoustic impedance of dirt, grass, sand, and asphalt.
Influence of reflections at the ground on insertion loss of barriers
Authors: Isei T. , Embleton T. F. W. , Piercy J. E.
Published: October 2005

Widely used curves for insertion loss due to barriers [e.g., Z. Maekawa, Appl. Acoust. 1, 157–173 0968)] make allowance for the presence of ground but do not allow for interference. These curves predict monotonically and smoothly increasing insertion loss with frequency from a low-frequency, i.e., low Fresnel Number, asymptote of about 5 dB. Pure-tone sound levels have been measured behind long plywood barriers (3/4 in. thick, 0.25–1.25 m high) over flat asphalt and grass-covered surfaces outdoors to distances of 4 m and for source and receiver altitudes from 0.02 to 2 m. These experimental results agree with an appropriate theory based on Kirchoff, Sommerfeld, and Maekawa, but extended to include both magnitude and phase of the ground reflection coefficients—in general different on each side of the barrier—and ground waves. The results as a function of frequency show systematic and predictable oscillations due to interferences, distributed about the monotonic curve that represents diffraction. The low frequency asymptote is either O dB or a gain of +6 dB, depending on whether the insertion loss is defined relative to a simple source in the presence of the ground or relative to the same source in free space.
High frequency sound attenuation in short flow ducts
Authors: Posey J. W.
Published: October 2005

Traditionally, sound propagation in flow ducts has been analyzed using modal theory. However, for high-frequency (duct height divided by free-space wavelength much greater than unity) sources near (the order of the duct height or less) the duct termination, mode theory may be unnecessarily burdensome and seems to obscure the basic simplicity of the propagation phenomenon. In this paper, geometric acoustics is employed to develop absorbent liner design procedures for the case of high frequency sources in short ducts. Point and line sources in a two-dimensional parallel plate duct are utilized to develop basic concepts, which are then extended to the point and distributed sources in a cylindrical duct. In each case, an optimal impedance distribution (or segmentation) is found for subsonic plug flow. The applicability of this approach to the design of inlet and exhaust noise suppressors for aircraft turbomachinery is discussed.
Dynamic information specifies vowel identity
Authors: Strange Winifred , Jenkins James J. , Edman Thomas R.
Published: October 2005

Research reported last year [W. Strange, J. J. Jenkins, and T. R. Edman, J. Acoust. Soc. Am. 61, S1 (1977)] was extended to investigate the contribution of dynamic spectral and temporal information to the specification of vowels. Two tokens each of ten American English vowels produced in /b/-vowel-/b/ syllables by four speakers were digitized and several stimulus conditions were constructed: (1) silent-center syllables (in which a variable-duration center “vowel” portion of each syllable was deleted). (2) variable-duration centers (with initial and final transitions removed). (3) fixed-duration centers (52 ms), and (4) long silent centers, and short silent centers (in which the temporal relations of initial and final portions were changed). Vowel identification was best for the silent-center syllables produced by three of four speakers. Vowels in the variable-duration center condition were identified better than in the fixed-duration center condition. Lengthening the silent centers increased errors while shortening did not. Effects of speaking rate, vocal tract differences, and dialect are discussed. [Supported by NIMH.]
The effect of the length of a lined duct on its average transmission loss in a frequency band
Authors: Cho Y. C.
Published: October 2005

An analytical investigation was made to determine the length dependence of the octave band transmission loss (OBTL) of a lined duct of the uniform cross section. One of the most interesting results is that the OBTL does not always increase in proportion to the length even in the absence of mean flow and self noise generation. This phenomenon, often observed in the design of silencers, is explained in terms of the distortion of the spectrum shape as the sound advances through the lined duct.
Applications of normal coordinate theory to very low frequency propagation
Authors: Tolstoy I.
Published: October 2005

In the linear theory of waves the use of exact mode theory is particularly indicated at low frequencies because the ray and WKB approximations are often invalid. This paper focuses on the normal coordinate technique, which uses mode amplitudes as generalized coordinates. This approach has the attraction of completely bypassing the need for a radiation condition, leading directly to travelling impulsive and transient solutions. It also automatically provides correct integral transform representations of the solution when the field operators or boundary conditions are nonstandard, e.g., not of the Sturm-Liouville type; the only restriction here is that such conditions must be conservative. These features are illustrated by the solution of an impulsive point source solution for a rigid surface with microroughness, a situation in which it has been shown (Biot, 1968) that the effect of roughness can be represented by non-standard types of boundary condition applied to a plane surface. The method of normal coordinates leads here to simple, closed form solutions.
Effects of variation of attenuation with depth in the sediment on the bottom reflection coefficient
Authors: Williams Winifred E. , Hawker Kenneth E.
Published: October 2005

The form of sediment attenuation versus depth is varied to study its effects on the bottom reflection coefficient for sand and clay layers. 300 m thick, overlaying a basalt substrate. Constant, linear, modified exponential, and sound-speed-linked dependences of attenuation on depth are input to a plane wave reflection coefficient model and the resulting bottom loss versus grazing angle curves are compared. The form of attenuation versus depth is found to have significant effects (as much as 10 dB at 50 Hz) on bottom loss for sediments with small critical angles and moderate sound speed gradients. Mode attenuation coefficients for the same physical situations gave similar results. [Work supported by the Naval Electronic Systems Command.]
Interpolation of normal mode eigenvalues in the frequency domain
Authors: Hawker K. E. , Payne S. G.
Published: October 2005

Direct computation of the Fourier inversion integral to obtain the time dependent pressure field for explosive sources using normal mode theory has been inhibited by the high resolution required in the frequency domain. Very large numbers of mode sets would normally be required even for bandlimited data. This number can be considerably reduced through the use of a sequence of narrow-band expansions based on the interpolation of eigenvalues between frequencies using a truncated Taylor series expansion. This approach relies on the use of very rapidly computable modal group velocities to obtain the first order term, dkn/dω. This paper shows the errors incurred in interpolating eigenvalues between discrete frequencies for several bandwidths and orders of approximation. Estimates of the second frequency derivative from a three point difference scheme are shown to considerably reduce the errors. Results thus obtained indicate that this approach, based on a sequence of narrow-band expansions, may make possible the extension of time independent normal mode modeling to the time domain. Also, this technique will have application in octave-band averaging of time independent propagation loss. [Work supported by the Naval Electronic Systems Command.]
Very low-frequency underwater sound propagation loss predictions for the NOSC tower site off Mission Beach, California
Authors: Northrop J.
Published: October 2005

Propagation loss predictions were made for the NOSC oceanographic tower at 6.1, 12.25, 25, 50, and 100 Hz. The tower is situated in 18 m of water about 1.6 km offshore. Drilling operations there show the sedimentary layers are 10 m of unconsolidated pleistocene and recent sands overlying about 1 km of the cretaceous Pt. Loma Formation. Layer thickness, density, porosity, attenuation, and velocity deduced from the cored sediment, seismic reflection profiles, and bottom samples obtained by divers [E. L. Hamilton et al., J. Geophys. Res. 75, 4039–4049 (1970); E. L. Hamilton, Geophysics 37, 620–646 (1972)] were used as input data to a normal mode computer program to predict propagation loss at the various frequencies. Results show that at 100 Hz, for example, the slope of the propagation loss versus distance curve is 3.7 dB/km, in the 5–25 km range interval, with greater slope at shorter ranges and lesser slope at longer ranges. Field measurements using both hydrophones and buried geophone cable connected to the tower are planned for later comparison. [Work supported by ONR.]