bluuebunny/crossref_metadata_2025 huggingface dataset:
Forward “masking” of responses from single fibers of the cat auditory nerve
Authors: Bauer J. W.
Published: October 2005

A forward masking paradigm was used to mask the responses elicited by a probe tone in an auditory-nerve fiber. By varying the frequency and level of the masking tone, masked threshold functions were obtained. For low probe tone levels the masked threshold functions were similar in shape to tuning curves obtained using tone bursts. The level of the masked threshold functions depended on the specific criterion selected for judging whether a response was masked. Varying the duration or frequency of the probe tone did not change the shape of the masked threshold functions, but increasing the probe tone level did. For some fibers with CF above 4 kHz, low-frequency maskers were more effective (lower levels re tuning curves) than maskers whose frequency components were near the fiber's CF. Thus, masked threshold functions resemble the tuning curves best for the tips of tuning curves best for the tips of tuning curves and may be significantly different for the tails. These results may be important in interpreting “psychophysical tuning curves” obtained with forward masking paradigms. [Work supported in part by NIH.]
Articulatory feature detection
Authors: Fujimura O. , Miller Joan E. , Escolar Gayle
Published: October 2005

How accurately can simple algorithms identify segmental gestures by direct observation of articulatory movements in connected speech? We have made a preliminary examination of this problem using x-ray data on the movements of six metal pellets placed on the tongue, lip, mandible, and velum [Fujimura, Miller, and Kiritani, J. Acoust. Soc. Am. 60, S64, (A) (1976)]. The data pertained to natural utterances of English sentences, at a speed of 4–6 syllables/sec. It is relatively easy to identify visually the labial, palatal/velar, and interdental consonants, respectively. In most cases this can be done by merely setting an appropriate threshold for the pellet coordinate value of the most pertinent articulator, particularly if we know how many of such events we should expect in the given utterance. By combining such feature detectors we can identify /p, b/, /m/, /f,v/, θ, ∂/, /k, g/, /η/, /∫/, and /r/ with high accuracy. Stressed syllables are mostly identifiable via mandible height. The domain of nasalization generally covers any string of nasal consonants and vowels uninterrupted by non-nasal true consonants. Data produced by two additional American speakers and similar data on Japanese are being examined. We acknowledge our thanks to Dr. S. Kiritani, University of Tokyo, for his cooperation.
Distinctive features: evidence from dichotic identification of 21 English consonants
Authors: Kirstein Emily , Hayden Mary Ellen , Sargent Margaret , Singh Sadanand
Published: October 2005

A dichotic tape was constructed from all possible ordered pairings of 21 spoken CV syllables, /pa, ta, ka, ha, da, ga, fa, va, θa, ∂a, ∫a, t∫a, d∫a, sa, za, wa, la, ja, ra, ma, na/. A computer was used to edit each syllable to a duration of 378 msec and to align syllable onsets for dichotic pairs. In an ear monitoring paradigm 10 female Ss were instructed to report the consonant at a designated ear. (Both attended ear and channel were controlled by counterbalancing.) A significant right ear advantage was found for the entire stimulus set and for those pairs involving only stops, only fricatives, and only sonorants. Consistent with previous studies, stops in pairs contrasting between ears in only one feature were correctly identified more often than in two-feature contrast pairs. However, for fricatives and affricates the reverse occurred, with correct responses increasing directly with number of contrasting features. Intrusions from the unattended ear were most frequent with one-feature contrast pairs and declined progressively with more contrasts. Analysis of nonintrusion errors revealed “blends” of features from opposite ears, not only with stop-stop pairs, but also for stop-nasal pairs, fricative-nasal, and fricative-stop pairs.
External and middle ears, the determinants of the auditory threshold curves
Authors: Khanna S. M. , Tenndorf J.
Published: October 2005

The pressure transformation ratio of the cat's ear under auditory free-field conditions was calculated from Nedzelnitzky's data [pressure in scala vestibuli (sc. v.) for a constant SPL at the tympanic membrane] with appropriate corrections applied for his open bulla and the tympanic membrane reference. For a constant SPL at the pinna, the pressure in sc. v. followed a curve identical to an inverted plot of the cat's free-field threshold. Therefore, when expressed in terms of threshold SPLs at the pinna, the pressure in sc. v. became independent of frequency, its absolute value being 0. 003 dyn/cm2. These results demonstrate the importance of the acoustic properties of ear canal and pinna. They also suggest that the free-field threshold curve is mainly determined by properties of the external and middle ears, including the inner-ear input impedance. The power entering the inner ear at threshold was calculated from cat impedance data of Lynch and Peake. Its value is about 10−18 W for frequencies between 50 and 7000 Hz. [Supported by NIH grants.]
Design of a vented box stage monitor speaker system
Authors: Stacy Keith
Published: October 2005

The role of the audio engineer in the design of a professional sound reinforcement system is becoming a more and more difficult and complicated one with the advent pre-equalized speaker systems that must operate at given sound pressure levels before feedback in less than ideal acoustical environments. Possibly the most feedback critical and important speaker systems in “the house” are the monitors—the speakers by which the performer judges himself. The systems engineer must be able to guarantee the acoustic output level over an ever increasing bandwidth approaching the limit of human hearing. Special emphasis must be placed on the high-frequency response if the system is to be useable for monitoring acoustic guitars and other instruments with high-frequency content. All this must be accomplished with regard to speaker “break-up,” efficiency, cost, and complexity. For these reasons a two-way system using a vented box enclosure seemed to offer an optimum solution for monitoring requirements.
Concorde supersonic transport noise monitoring program
Authors: Foster C. R. , Sellman E. W.
Published: October 2005

The operational specifications of Air France and British Airways were amended to allow limited scheduled commercial flights of the Concorde supersonic transport into the United States for a trial period not to exceed 16 months. An interagency steering group comprised of representatives from the Secretary, National Aeronautics and Space Administration (NASA), Environmental Protection Agency, and FAA developed plans for noise, sonic boom, community response, and low-altitude pollution monitoring. Measurements have been taken since initiation of Concorde operations into Dulles Airport on 24 May 1976. Two community opinion surveys around Dulles Airport have been completed and the first JFK opinion survey was started on 1 February 1977. Results of the first two Dulles area surveys indicate that fewer people now disapprove of the Concorde than at the time of initiation of operations. Later surveys will provide results which may be compared to the first survey to detect changes in attitudes. A content analysis of print and broadcast media is being conducted to determine their treatment of the Concorde issue. Structural vibration studies conducted by NASA at Sully Plantation and in typical residences showed that Concorde caused more vibrations in the structures than other aircraft but not as much as nonaircraft events such as doors closing.
Acoustic transients in pulse-echo systems
Authors: Andrew G. A. , Stepanishen P. R.
Published: October 2005

An approach is presented to analyze the transient behavior of a piezoelectric transducer in a pulse echo system using FFT algorithms. The radiation field is described using impulse response and Fourier integral techniques [P.R. Stepanishen, J. Acoust. Soc. Am. 60, S100 (A) (1976)] whereas the transducer is described via the use of a distributed parameter model which includes piezoelectric losses. The approach can be used to readily evaluate the near field time dependent pressures which result from short pulse electrical excitations of a transducer. The receiving response of the transducer for the short pulse excitation can then be readily evaluated for the case of idealized scatterers in the acoustic near field. Extensive numerical results are presented for the near field pressures and receive voltages which result from the short pulse excitation of a piezoelectric disc operating in the thickness mode. For pulse durations which are less than the travel time across the disc, a multipulse structure is clearly observed in both the field pressures and the receive voltages. [This work was supported by NIH.]
Ultrasonic enhancement of cancer radiotherapy
Authors: Kremkau F. W. , Witcofski R. L.
Published: October 2005

The ability of elevated temperatures to reduce the amount of x irradiation required to locally control transplanted tumors has been reported. As part of an investigation of combined x-irradiation and ultrasound treatment, we have studied the response of subcutaneously implanted C3H mammary tumors (C3HMT) and sarcoma-180 (S-180) to either radiation or radiation and ultrasound in 330 animals. Ultrasound (1.9 MHz, continuous wave, 1.5 W/cm2 spatial average) was delivered to the 7-mm-diam. tumors in a water bath for 15 minutes. Ultrasound alond did not affect the growth of either type of tumor. For combined treatment the endpoint observed was the ability of ultrasound to reduce the radiation dose required to locally control 50% of the tumors (TCD50). Sound treatment before or after irradiation of the C3HMT did not result in a TCD50 different from that for radiation alone. For the S-180 tumor, a TCD50 of 2500 rad was obtained with X-ray treatment. Treatment of S-180 tumors with ultrasound immediately after x irradiation reduced the TCD50 by approximately 1000 rad. [This investigation was supported by Grant Number CA 17581, awarded by the National Cancer Institute, DHEW.]
Interaction of spectrally-mismatched continuous and impulse-noise exposures in the chinchilla
Authors: Blakeslee E. A. , Hynson K. , Hamernik R. P. , Henderson D.
Published: October 2005

Combinations of “safe,” spectrally overlapping continuous and impulse-noise exposures have been shown to have a potentiating interaction [R.P. Hamernik et al., J. Acoust. Soc. Am. 55, 117 (1974)]. The present study was designed to determine whether matching of the impulse and continuous-noise spectra is a necessary condition for the interaction effect. Ten monaural chinchillas were exposed to a combination of 60 min of 500–1000-Hz noise at a level of 100 dB SPL and 50 impulses (CF ≈ 6 kHz; 40 μsec A duration) presented at a peak pressure of 158 dB SPL and a rate of 1/min. Thresholds were determined before and after exposure using either averaged-evoked-response AER) or shock-avoidance conditioning audiometry. A control group of five monaural chinchillas was exposed to the continuous noise alone. The control animals developed no permanent threshold shifts and two of the five animals had slight cochlear damage. The aforementioned study (Hamernik et al., 1974) showed that the 158 dB, impulse-noise exposure also produced no PTS and three of eight animals had slight cochlear damage. However, of the animals exposed to the combined noises, five of ten animals had a significant increase in TTSmax over the controls and these same five animals developed a significant PTS (>15 dB) after 30 days of recovery. Of the five cochleas which have been histologically examined, three show moderate to heavy damage. Our tentative conclusion is that the spectrally mismatched combination has an interaction with increased traumatic power, but the effect is not as great as when the spectral distribution of the impulse and the background noise is more closely matched.
Hearing and sound localization in the kangaroo rat (Dipodomys merriami)
Authors: Heffner H.
Published: October 2005

Hearing thresholds were determined for two kangaroo rats using a two-choice procedure with an observing response. The animals were trained to initiate a trial by entering a small observing compartment located in front of a loudspeaker. The kangaroo rats were then rewarded for entering a compartment located on their left if a tone were present and for entering a compartment located on their right if no tone were present. Entry into a compartment was detected by a photocell and correct responses were rewarded with millet seed which was dispensed into the correct compartment. The kangaroo rats successfully responded to frequencies ranging from 50 Hz to 64 kHz. The two-choice procedure was then used to determine the ability of the animals to localize single clicks. The results of these tests indicate first, that the kangaroo rat possesses good high- and low-frequency hearing and, second, that it can locate the source of a brief sound. [Work supported by NIH grants NS12992 and HDO2528.]
Complex tonal perception through hearing aids
Authors: Bowling L. S. , Schweitzer H. C. , Causey G. D.
Published: October 2005

The influence of nonlinear distortion in hearing aids on three tone complex perception was evaluated in a comparison paridigm requiring a Same/Higher/Lower pitch judgment. Thirty normal-hearing subjects listened to recordings of the simultaneous tones 888, 1000, and 2140 Hz processed by two hearing aids and the hearing-aid test system alone. A comparison signal differed only in the center frequency, which was varied over a 40 Hz range. Hearing-aid—generated non-linear distortion improved the accuracy of the same judgments. The evidence of confusion errors for the Higher and Lower stimuli were significantly greater for the low-fidelity conditions. Cubic difference tones (CDT), identified in the hearing-aid outputs, appeared to relate to the direction of the listener confusions. The results for the two hearing aids were essentially the same in spite of substantial difference in amounts of nonlinear distortion. [Work supported by VA.]
Discrimination of symmetric, time-intensity traded stimuli
Authors: Ruotolo B. Robert , Stern Richard M. , Colburn H. Steven
Published: October 2005

New experiments have been conducted to determine the extent to which listeners can discriminate between different combinations of interaural time and interaural amplitude for stimulus configurations which eliminate loudness, lateralization, and image-diffuseness cues. A 21, 2AFC paradigm was used and the task of the subject was to determine the order of two stimuli, each of which was a slowly gated 500-Hz tone with an interaural time and amplitude combination that resulted in a centered image. The two stimuli to be discriminated were symmetric in that they differed only in the polarity of the interaural differences. Also, in order to reduce artifacts introduced by variations in the coupling of the earphones to the head, acoustic monitoring was performed both before and after each experimental run. For three of the four subjects tested, discrimination performance was at the chance level. However, the fourth subject (the experimenter) was able to perform well above chance after extensive practice utilizing a special listening technique. His perceptions were not consistent with models predicting a “time” image and a “time-intensity traded” image. [Work supported by NIH.]
Relation of some personality types to annoyance response to noise
Authors: Shigehisa T. , Gunn W. J.
Published: October 2005

Subjects were classified into several groups based on their scores on extraversion, neuroticism, psychoticism, and lie scales of the Eysenck Personality Questionnaire. They were instructed to estimate the magnitude of annoyance of 27 aircraft noise stimuli while engaged in viewing television. Test/retest correlations between average annoyance estimations (over the 27 noises), slopes and intercepts of annoyance function in three test sessions (three different conditions of test room illumination), as well as split-half reliabilities, showed that annoyance measures were stable and consistent among the subjects. The slope increased and the intercept decreased when the illumination was lower than ordinary in psychotics (but not in nonpsychotics) and in low-L scorers (but not in high-L scorers). The intercept tended to correlate positively while the slope correlated negatively with introversion, when illumination was brighter, and the slope correlated negatively with neuroticism whet illuminations was dimmer. The average estimation measures showed that hysterics (neurotic extroverts) are high annoyance estimators, where dysthymics (neurotic introverts) are low annoyance estimators of noise at relatively high levels (ranging from 84 to 92 dBA, peak value).
Anchoring effects on a synthetic consonant continuum
Authors: Simon Helen J. , Studdert-Kennedy Michael
Published: October 2005

Anchoring effects on several acoustic continua were studied by manipulating the probabilities of occurrence of end-point stimuli. Two six-step double continua were constructed by simultaneously varying both the initial formant transitions of a CV syllable and either its pitch or its vowel. Thus, the first continuum ranged from low-pitched /bae/ (114 Hz) to high-pitched /dae/ (150 Hz); the second from /bae/ to /dɛ/. Two random-order test tapes were prepared for each double continuum: in one (control) all seven stimuli occurred equally often, in the other (anchor) an end-point stimulus (either /bae/ — “low” or /bae/ occurred four times as often as each of the other six stimuli. Nine subjects listened to each tape twice, once judging the initial consonant of each syllable (/b/, /d/), once judging either its pitch (low, high) or its vowel (/ae/, /ɛ/). On the first test, the mean category boundary was significantly shifted toward the anchoring stimulus on the pitch judgment, but not on the consonant judgment. On the second test, the mean category boundary was significantly shifted toward the anchor stimulus on both vowel and consonant judgments. Judgments of synthetic consonants are thus not always immune to the psychophysical effects of anchoring. [Work supported by NICHD.]
Response bias and subjective estimation of consonant frequency
Authors: Goldstein Louis , van den Broecke Marcel
Published: October 2005

Do people have expectations about the frequency of occurrence of consonants in a given context and if so, do such expectations manifest themselves as consistent response biases in perceptual confusions? Subjective estimates of the frequency of selected /ιC/ syllables in English were measured. Subjects were auditorily presented with pairs of syllables and were asked to judge which member of the pair was the more frequent sound sequence in English. The scaled frequency judgments correlated highly (r = 0.84, p < 0.001) with consonant frequencies in the same environment in published counts, Available data on perceptual confusions was analysed to determine if there was any consistent response bias. Consistent differences among various consonants in terms of their tendency to occur as responses would constitute a response bias. The number of times a certain consonant was given as a response in the material examined did not correlate with that consonant's frequency of occurrence. Such consistent response biases as did occur were due to asymmetric relations within a small subset of the total set of consonants. [Work supported by NSF, Z.W.O.]
Anticipatory coarticulation in dyads
Authors: Olive J. P. , Nakatani L. H. , Bachenko Joan
Published: October 2005

Speech can be synthesized by concatenating dyads representing the transition between phoneme pairs. The resulting speech should be well coarticulated if the dyads themselves are free of coarticulatory influences and are therefore independent of context. We tested dyads for anticipatory coarticulation in 151 words as follows. Within each word, the /XæY/ sequence, where /X/ and /Y/ were consonants. were dyadically synthesized. The word /pæn/, for example, was synthesized with the dyads /pæ/ and /æn/. The /pæ/ dyad was an archetypal form derived from many words (pan, papoose, pad, sphagnum, etc.); the /æn/ dyad was taken unchanged from /pæn/. Only the segmental features were synthesized; the prosodic features were left intact. Listeners noticed degradation in words where anticipatory coarticulation of a nasal /Y/ consonant caused /æ/ to be nasalized: words with non-nasal /Y/ were well synthesized. We conclude that nasalized vowels are needed in dyadic synthesis to cope with anticipatory coarticulation of nasal consonants.
Low-resource system for all-digital speech synthesis
Authors: Herman George , Duquet Robert T.
Published: October 2005

A program for all-digital speech synthesis by rule was developed for a Nova 800 computer with limited memory and no hardware multiplication. The objective was to provide commands which are easy to use, reasonably rapid computation, and great flexibility in the design of output, within the resources of a very small system. In the process, a number of novel approximations and shortcuts were adopted. Most of these succeed in providing speech as natural and intelligible as was hoped for. Unusual features include the reading of the “glottal waveform” from table storage, generation of formants by addition rather than multiplication or digital filtering, use of fixed formant bandwidths and relative formant amplitudes, and stored narrow-band pseudorandom noise for fricatives. The system is controlled by stating six parameters: fundamental frequency, three formant frequencies, amplitude, and noise band. These need be stated only at a small number of time coordinates; the program uses linear interpolation to supply intervening values. The entered data are displayed on a screen in the form of a simplified spectrogram accompanied by graphs of frequency and amplitude vs time, for a 1-sec segment. Segments can be stored, truncated, and concatenated for delivery to the digital-analog converter.
Simple pitch-dependent algorithm for high-quality speech-rate changing
Authors: Neuburg Edward P.
Published: October 2005

A time-domain algorithm for speeding up or slowing down speech is described. Present cut-and-splice methods preserve pitch contours and spectral shape, but produce buzzy speech, even if care is taken to blend or match edges of segments. The new method is a variant of cut-and-slice; it consists of a crude pitch detector followed by an algorithm that discards (or repeats) pieces of speech equal in length to a pitch period, then blends together the ends of the pieces that are retained. The method is easily implementable in real time, and is effective for noisy speech. The method is not pitch-synchronous. Rate changes from 0.5 to 2.0 sound natural; slowdown to 0.1 is intelligible. The method has been used (experimentally) in conjunction with silence removal to compress speech 4/1 and then reexpand to a signal that is perceptually almost identical to the original.
Chladni patterns and the modes of a circular steel plate
Authors: Rose C. D.
Published: October 2005

Chladni patterns have proven to be a useful tool in both teaching and research. Chladni patterns, obtained when a “free-free” circular steel plate is driven in steady state, are employed to study the normal and combined modes of vibration. The frequencies of the normal modes are compared to the number of nodal diameters and nodal circles. When two normal modes have nearly the same frequency a linear combination can occur. [Acustica 3, 135 (1953)] The resultant nodal patterns for different proportions of the individual normal modes will be discussed.
Alcohol has little effect on TTS
Authors: Ward W. Dixon , Cushing E. M.
Published: October 2005

Ten young normal-hearing adults were exposed to magenta noise in 27-min bursts with 33-min interburst pauses. The level of successive bursts increased in 5-dB steps from 90 dBA to 105 dBA. In the experimental condition, listeners drank the equivalent of 3 oz. of grain alcohol in the period between the end of the 90-dBA exposure and the beginning of the 105-dBA exposure. In the control condition, no alcohol was ingested. Mean temporary threshold shifts at 500, 1400, and 4000 Hz measured via Bekesy audiometry 2 min after exposure (TTS2) were identical in the two conditions, even after the 105-dBA exposure. However, TTS32 was slightly higher in the intoxicated condition (by 2 dB, which just achieves significance at the 5% level). The result is interpreted as showing the effects of alcohol on threshold-finding behavior rather than on auditory fatigue per se. [Research supported by the National Institute for Occupational Safety and Health, Public Health Service, although they did not specifically authorize this particular study.]
Dependence of TTS on signal duration: Energy scattering and/or disturbances of temporal summation
Authors: Brown Richard K. , Ward W. Dixon
Published: October 2005

It has been shown that TTS is smaller for shorter test signals [J. F. Jerger, J. Acoust. Soc. Am. 27, 121–124 (1955)]. However, shortening the test signal results in the scattering of of energy to adjacent frequencies. It is therefore possible that the threshold response to shorter signals is mediated by unfatigued neural elements near those elements that normally are maximally responsive to the test frequency. Ten subjects were exposed on separate occasions to one-third-octave bands of noise centered at 2500 and 630 Hz, respectively, in order to produce a localized TTS at 4000 Hz or at 1000 Hz. They were also exposed on separate occasions to magenta noise (a noise designed to produce equal TTS at all frequencies) and to white noise (as employed by Jerger). This hypothesis predicts that the difference between the indicated TTS employing short signals and that using long signals should be smaller after exposure to magenta noise than after exposure to either narrow-band or white noise. This prediction was confirmed: The difference in TTS indicated by 4- and 400-msec signal durations was 6 dB when the TTS was produced by the 2500-Hz narrow-band noise, but only 3 dB when it had been generated by the magenta noise. Apparently, then, part of the disparity in TTS can be attributed to energy scattering, but the “temporal summation” mechanism (assuming there is one) must also have been affected by the process that produces TTS. [Work supported by the National Institute for Occupational Safety and Health, Public Health Service.]
Required attention for synthesized speech perception for two levels of linguistic redundancy
Authors: Simpson C. A. , Hart S. G.
Published: October 2005

It was hypothesized that additional contextual linguistic redundancy in the wording of synthesized speech cockpit warnings would result in less required attention for initial comprehension and subsequent recognition. Twelve airline pilots were repeatedly presented 16 unfamiliar warnings in two wording formats, key word and sentence; e.g., Fuel low, compared to The fuel pressure is low. Then they heard the same warnings embedded in weather broadcast at a warning-to-weather sound pressure level ratio of +3 dB. For both listening conditions the task was to read back the message and also estimate the passage of time during message comprehension or recognition. Peformance on time estimation had previously been found to correlate with hypothesized attention demands during manual tracking and aircraft simulator flying tasks. As expected in the present study, intelligibility was higher and response time shorter for the sentence format than for the key word format. For unfamiliar messages, the tendency to underestimate the passage of time was greater for the two word format than for the sentence format, implying that less attention was available for the time estimation task during comprehension of messages with less linguistic redundancy. By contrast, for familiar messages there was no significant difference in performance on the time estimation task for the two levels of linguistic redundancy. Possible reasons for the difference in attention requirements for comprehension compared to recognition will be discussed. [Work supported by NASA Grant NGL 05-046-002 to the San Jose State University Foundation.]
Effects of noise on short-term memory of consonants
Authors: Rastatter M. P. , Danhauer J. L. , Herman G.
Published: October 2005

The purpose of this study was to investigate intrusion errors for consonants in short-term memory (STM) when perceived in varying signal-to-noise (S/N) ratio conditions. Stimuli were eighteen English consonants paired with the vowel /a/, and presented in groups of nine blocked in threes. Twenty-seven phonetically trained college students were separated into three groups of nine subjects each. Subjects in each group heard the stimuli in either (1) 0 dB S/N, (2) −5 dB S/N, or (3) −10 dB S/N ratios (re MCL); transcribed their responses; covered them; and recalled items from STM. A paradigm described earlier [W. Wickelgren, J. Acoust. Soc. Am. 39, 388–398 (1966)] was used for stimulus presentation and recording of results. Subjects' error data were submitted to INDSCAL and analyzed for distinctive features. Features were compared across noise conditions and to earlier studies. Data were also analyzed in terms of number correct.
Changes in speech as a function of alterations in the oral and auditory environment
Authors: Garber S. R. , Speidel T. M , Glass L.
Published: October 2005

Speakers may be forced to alter their speech and physiological patterns when they are fitted with a dental prosthesis. In the present study, speech alterations were assessed as a function of the speech task, the dimensions of the prosthesis and the speaker's auditory environment. Each of 24 normal subjects read lists of syllables, words, and sentences and spoke spontaneously while wearning no prosthesis, a thin (1.5 mm) prosthesis covering the entire palate, and a thick (3 mm) prosthesis covering the palate. All tasks were completed in quiet and in the presence of a 90 dB SPL speech noise. In a variety of acoustic and perceptual analyses, speech deteriorated as the thickness of the prosthesis increased, and when noise was presented. There was no interaction between the effects of the noise and the prostheses on speech. Although differences between conditions generally reached statistical significance, subject variability was striking. [Work supported by an NIDR postdoctoral fellowship awarded to S. R. Garber.]
Coarticulatory effects in speech adaptation
Authors: Hamlet S. L. , Stone M.
Published: October 2005

Experimental prosthodontic modification of alveolar contour induces a compensatory form of articulation. The initial effects on speech, noticeable particularly during the first few days of adaptation, are heard as lisping and a general indistinctness in articulation. After two weeks of adaptation, when articulatory compensations have been learned, the speech of most subjects sounds essentially normal. It would seem that the reorganization in this motor task must involve a reestablishment of subtilties in articulatory coordination. Data on jaw motions and tongue/palate contacts were analyzed to see the extent to which coarticulatory phenomena in VCV environments would be preserved in initial attempts to speak with a prosthesis and after adaptation to it. [Work supported by NIH.]
Mothers' simplification of phonetic input to their children in English and Polish
Authors: Moslin Barbara J. , Keating Patricia A.
Published: October 2005

Voice onset time measurements were made of three mothers' productions of word-initial spiral stops to their 18 month old children in order to determine whether mothers play a significant role in their child's acquisition of the voiced—voiceless distinction. Two of the mothers spoke native English to their children, and one spoke native Polish. Measurements were also made of each mother's productions of word-initial stops to another adult. Results show that mothers speak differently to their 18 month old children than they do to other adults. All three mothers employed certain clarification strategies for reducing the overlap of VOT values between voiced and voiceless categories which exists in normal adult adult discourse. These strategies included an increase in the median VOT values for productions of the voiceless stop, and/or a reduction in the range of VOT values for the voiceless category. Mothers, therefore, seem to be facilitating the task of phonological acquisition for their children by presenting them with a maximally distinct, tailored phonetic input. [Work supported by NICHD.]
Comparison of nearfield and farfield methods for studying ultrasound induced optical birefringence in liquids
Authors: Riley W. A.
Published: October 2005

Early studies of ultrasound induced optical birefringence in liquids were performed in the near optical field of the ultrasonic grating. More recently, a farfield method has been developed for studying the effect. The range of experimental conditions under which the respective methods may be accurately applied vary significantly. In addition, the methods differ considerably in their abilities to provide measurements from which theories for the effect can be directly evaluated. Experimental results obtained from each method in castor oil are compared to illustrate the significant differences which occur and to clarify the advantages and limitations of each method.
Observations in drying pulverized coal using an ultrasonically vibrating trough
Authors: Otsuka T. , Fairbanks H.
Published: October 2005

The purpose of this investigation was to study the influence of applying ultrasonics directly to a heated inclined drying trough in drying of thermal degradable powders such as desulfurized pulverized coal. A frequency of 20-kHz was used with intensities up to 150 W. The variables studies included: Ultrasonic intensity, temperature and slope of trough. It was found possible to convert 40%–60% of the heat into the evaporation of the moisture from the coal; 10% to heat the coal and moisture to the evaporation temperature; the remaining heat was lost by radiation and convection into the environment. It is conjectured that the direct addition of ultrasound to the drying trough aided both the moisture flow and heat transfer to the evaporating surface.
Acoustic impedance measuring device for marine sediments
Authors: Shirley D. J.
Published: October 2005

As part of a program to measure acoustic properties of marine sediments in situ, a device has been developed to measure the acoustic impedance ρc of such sediments. With concurrent measurement of sound speed c the bulk density ρ of relatively undisturbed sediments can be obtained. Acoustic impedance is obtained by measuring the electrical driving impedance at resonance of a small ceramic transducer element in contact with the medium. Relationship of the electrical impedance z to the acoustic impedance ρc, as well as the effect of temperature on the measurement has been examined and will be reported. [Work supported by ONR.]
Individual differences in vowel recognition
Authors: Greenberg Steven
Published: October 2005

Dorman et al. [Haskins Laboratories, Status Report on Speech Research SR 37/38 (1974)] observed that their experimental population could be divided into two groups on the basis of performance in a backward recognition masking paradigm. The experiments reported here attempt to resolve whether the pattern of individual differences originally reported by Dorman and colleagues derives principally from variability in (1) the rate of access to short-term verbal memory, or (2) the precision of acoustic-phonetic discrimination. Stimuli for Experiment I consisted of three synthetically generated, 24-msec vowels ([I], [ɛ], [æ]) followed at a variable interval (0–320 msec) by a vowel-like [εΓ] mask. Response patterns of individual subjects segregated into one of two discrete types, consistent with Dorman et al.'s “masker”, “nonmasker” dichotomy. However, experiment II, using four target stimuli ([I], [ɛ], [æ], [a]) and two masks ([εΓ], [o]) witnessed a significant narrowing of the performance gap between the “masker” and “nonmasker” groups, raising certain doubts about the role played by short-term verbal memory processes in the differentiation of “maskers” and “nonmaskers.” [Research supported by NSF and USPHS.]
Transconsonantal context effects on vowel recognition latency
Authors: Martin James G.
Published: October 2005

The stimuli were spoken vowel-consonant-vowel sequences in the frame “I say V1 C V2” in which V1 was /u, æ/, C was /p,t,k/and V2 was /a,i/ in all 12 combinations. Reaction time (RT) of practiced listeners was observed to the assigned final stressed vowel target (V2). Experimental manipulations were: (a) pre-stop-consonant silence either was or was not extended by 100–200 msec and (b) the sequence either was or was not cross spliced at the silent interval. Extended silence alters the acoustic-phonetic structure of the stimulus, and it possibly allows extra time to process appropriate anticipatory cues (if any), or inappropriate anticipatory cues (if any) when cross spliced, to the target vowel. Among the results discussed are both relatively faster and slower RT which were produced by these manipulations and their interactions with target. [Supported by ARIBSS.]
Scanning acoustic microscopy—a new diagnostic tool with wide applicability
Authors: Weglein R. D. , Wilson R. G.
Published: October 2005

In this paper we describe the basic operating principles and performance characteristics of Scanning Acoustic Microscopy (SAM). Two selected applications of this emerging diagnostic technology are in the semiconductor industry as a defect-detecting instrument for large-scale integrated circuits and in medical diagnostic (cytology) for the rapid examination of tissue. The pulsed-reflection version of the SAM is well suited to the former application because of the acoustically thick materials involved there. The major emphasis in this paper is on that version of the instrument. Raster-scanned images show resolution of about 1.3 μm at our 375-MHz operating frequency and an image contrast range in excess of ten gray levels. Image resolution as well as the origin and measurement of acoustic contrast will be discussed vis-a-vis measured results. The use of a cW transmission acoustic microscope utilizing phase information to examine biological tissue is also briefly discussed (courtesy of C.F. Quate, Stanford University). Ultimate performance limitation will be projected. [This research funded by the Advanced Research Projects Agency Order 2397 through the National Bureau of Standards' Semiconductor Technology Program Contract 5-35898 (Hughes) and Contract 5-35899 (Stanford).]
Digital adaptive TVG control for grey-scale ultrasonic echocardiography
Authors: Lam Edward H. T. , Miller N. B.
Published: October 2005

In echocardiography wide-dynamic-range (∼90 dB) ultrasonic signals must be compressed for display to ∼15 dB with minimum image distortion. Large dynamic range is caused by absorption, scattering, dispersion, and by reflection from cardiac interfaces at varying angles of incidence. Echo levels in sector-scanning echocardiography differ with look angle, precluding operator adjustment. Thus, sector scanners need adaptive TVG profiles, or AGC. A digital, real-time, adaptive TVG for sector-scanning echocardiography is described herein. This technique is not subject to analog realizability constraints. The described adaptive TVG uses image data stored in a minicomputer to calculate a slowly varying TVG profile which commands a voltage controlled amplifier. The gain-profile algorithm is basic to the adaptive TVG. The grey-scale display quality of the echo output of the voltage controlled amplifier is examined and discussed. Alternatively, the technique permits the TVG input to be numerically recovered off-line and normalized relative to the average level in the neighborhood of each image point. Preliminary echocardiographic tests are discussed using one-dimensional data. The multidimensional adaptive TVG technique is currently being implemented in a scanning echocardiographic camera. [Work partially supported by NIH Grant 1 R01 HL20872-01.]
Observation of pulsed medical ultrasound gratings in the optical farfield
Authors: Riley W. A. , Barnes R. W.
Published: October 2005

A simple optical method is described for studying ultrasonic pulses as short as two or three cycles in duration in the low-megahertz frequency range. An incident collimated light beam having a width of one ultrasound wavelength is observed in the optical farfield of the ultrasonic grating midway between the maxima of the central and first diffraction orders. A close approximation to both the amplitude and phase of the acoustical pressure along the light path is obtained. The simplicity and reproducibility of this method warrants its consideration as a procedure for calibration and comparison of the transmit pulse characteristics of medical ultrasound systems. [Work supported by NINCDS Grant NS-06655 and a grant from North Carolina United Way.]
Computer system for auditory research (RAP-III)
Authors: Engebretson A. M.
Published: October 2005

The RAP-III is an extension of the original RAP [Spenner et al., J. Acoust. Soc. Am. 55, 427 (1974)] and it has been designed to meet conflicting requirements of large storage capacity and high-quality sound reproduction, simplicity of use, flexibility of application in auditory research whether in the laboratory or clinic, and low cost. Housed in a convenient cabinet are the following: a minicomputer CPU board, a 16k×16 memory, a disk drive and controller, a two-channel analog subsystem, a laboratory interface subsystem, and a keyboard/display terminal. The system can record and playback at arbitrary times in arbitrary sequences 101.5 sec of sound, control experimental conditions, and record responses. Once programmed for a particular class of experiments, the RAP-III can be operated as a turnkey, stand-alone system. Two systems have been assembled and several more are scheduled to be built. The laboratory-based RAP-III's are supported by a larger central system that is used for program development and data processing. [Supported by NS 03856 and RR 00396.]
Noise-induced increased responsiveness in the acoustic reflex mechanism
Authors: Ruth R. A. , Niswander P. S.
Published: October 2005

Acoustic reflex thresholds were obtained from ten normal-hearing adults both prior to and following exposure to wide-band noise of varying duration and intensity. A sufficient number of postexposure acoustic reflex thresholds were determined to permit the generation of recovery contours. Consistent with previous studies, threshold of the acoustic reflex was substantially lowered by application of a short-term exposure of moderately intense noise. An average of 10 dB of sensitization was produced by exposure to a 100 dB SPL, 120-sec wide-band noise signal as measured at the 0.5-min postexposure test interval. The magnitude of sensitization was dependent primarily upon the intensity of the noise exposure and, to a lesser extent, upon its duration. The maximum amount of reflex threshold shift was nearly always observed at the first postexposure measurement period, which was 30 sec following cessation of the noise. The degree of sensitization decreased systematically with time reaching full recovery from between 6 min to beyond 10 min depending upon exposure condition.
Effects of frequency-modulated signals on the threshold and persistence of the acoustic reflex
Authors: Boyer P. M. , Melnick W.
Published: October 2005

The effects of signal spectrum and loudness on the threshold of arousal and persistence (ability to maintain response to sustained stimulation) of the acoustic reflex (AR) of the middle-ear muscles in man were studied using pure tones (PT), narrow-band noise (NBN), and frequency-modulated (FM) tones at two frequency regions (500 and 2000 Hz). A separate sample of nine normal-hearing adults served as subjects for each frequency region. Changes in impedance at the tympanic membrane were used as an indirect indication of the AR. To control for loudness, spectra of all signals used were contained within one critical band for loudness, and subjects performed equal-loudness judgments for the three types of signals. Results did not support the concept that AR thresholds are loudness governed. The data indicated the AR mechanism acts more like an intensity detector than a loudness detector. Despite the spectral complexity, FM signals yielded the AR thresholds at SPL's similar to those elicited by PT stimuli. Less intensity was needed to initiate AR's when NBN was the stimulus. Changes in AR response magnitude over time (decay), observed for 2-min periods of FM stimulation, were similar to those which occurred with pure tones, rather than noise.
Timing effects on articulatory organization
Authors: Harris K. S. , Baer T.
Published: October 2005

A simple model of timing control suggests that the commands for articulatory movements are the same for different speaking rates, and different stresses, but that their temporal spacing changes. The result of this change in temporal spacing is a change in articulatory target, due to the sluggishness of the articulators [B. Lindblom, J. Acoust. Soc. Am. 35, 1773–1781 (1963)]. A test of this hypothesis was made by comparison of acoustic signal, articulator movement measured by lateral view cineradiography, and EMG signals for a nonsense disyllable, produced with variable stress and speaking rate. Results suggest that commands it the articulators are reorganized under the various conditions. [Work supported by NINCDS grant NS 13870 and NIDR grant DE 01774.]
Pulse propagation in the ocean. I: The fast field program method
Authors: Kutschale Henry W. , Tappert Fred D.
Published: October 2005

Long-range propagation experiments are often conducted in range-dependent environments. The prediction of pulse propagation characteristics in such environments is possible with the parabolic equation (PE) method, using the Tappert—Hardin split-step Fourier algorithm. A program has been developed to compute temporal waveforms from broadband sources as a function of range and depth, using Fourier synthesis to coherently add up the frequency response as obtained from the PE code at each range step. The effects of range-dependent ice roughness are modeled by a modified formula of Marsh and Mellen, using as input the rms ice roughness along the propagation path. The computed waveforms have been tested against field data on SOFAR propagation in the central Arctic Ocean, and excellent agreement has been obtained. Numerical simulations of pulse compression in the Arctic channel using predistorted waveforms to match the dispersion of the channel at specified ranges show in detail the possibility of successfully achieving significant signal gain by pulse compression.
Stochastic Green's functions and random walks
Authors: Vazholz David P.
Published: October 2005

In previous work [D. P. Vasholz, J. Acoust. Soc. Am. 60, S33(A) (1976)] a general black-box approach to wave propagation through a randomly fluctuating medium based upon the stochastic Green's function G was presented. Motivated by parallels with quantum field theory the quantities 𝒢 and M, related to the first and second moments of G, were defined. It was then shown how these quantities may be conveniently used to describe such effects as frequency broadening and coherence losses induced by the medium. In the present work it is pointed out that stochastic Green's functions readily lend themselves to interpretations of recent experimental work which have been made in terms of the random walk taken by the time-varying transfer function in the complex plane [W. H. Munk and G. O. Williams, Nature 267, 775 (1977)]. In particular it is shown how these random walks arise in a stochastic Green's function formulation and how their principal parameters may be very simply expressed in terms of 𝒢 and M.