bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of “modulation” in speechlike signals I: Matching amplitude depth to frequency extent
Authors: Porter Robert J. , Miller Creigton J.
Published: October 2005

A recurring proposal in the auditory literature is that variations in frequency and variations in intensity may, in some instances, have equivalent perceptual consequences. Some versions of this proposal argue for the existence of a psychological dimension of “modulation” nearly orthogonal to those of pitch and loudness [e.g., E. Zwickler, J. Acoust. Soc. Am. 34, 1425 (1962)]. Such a dimension may play a role in phonetic perception [L. Chistovich, Fiziol. Chel. 3(6), 1103 (1977)]. The study to be discussed examines this proposal by asking listeners to adjust amplitude variations to match speechlike frequency variations in second formant signals. The frequency variations are produced by changing the center frequency (by 100, 200, 300, or 400 Hz) of a second formant resonance over a 60 or 120 ms (hayersine shaped) interval which is temporally centered in a 600-ms signal. Comparison signals are temporally analogous second formants in which the depth of a hayersine amplitude modulation can be adjusted. Preliminary results for one listener reveal a systematic relationship between adjusted amplitude depth and the extent of frequency variation in the standard; the nature of the relationship is consistent with a “modulation” perception interpretation. [Supported in part, by NIH/NINCDS NS ♯ 11647 and the Louisiana Eye and Ear Foundation.]
The effects of training on intelligibility of synthetic speech: I. Pre-test and post-test data
Authors: Schwab Eileen C. , Pisoni David B.
Published: October 2005

Several previous experiments have suggested that the intelligibility of synthetic speech can be improved with practice. However, an alternative interpretation of this research is that subjects simply learned to perform the experimental tasks better without any change in intelligibility. To test these alternatives, we conducted an experiment to separate the effects of training on task performance from improvements in the intelligibility of synthetic speech. Three groups of subjects were tested on day 1 (pre-test) and day 10 (post-test) of the experiment with synthetic speech generated by the Votrax Type-N-Talk text-to-speech system. One group received training with synthetic speech on days 2–9; a second group received exactly the same training procedures on days 2–9 with natural speech; the third group received no training at all. Intelligibility was assessed for isolated words, syntactically correct meaningful sentences, syntactically correct but semantically anomalous sentences, and prose passages. In this paper, we will discuss the effects of training measured by changes in intelligibility between the pre-test and the post-test. The implications of these results for applications of low-cost text-to-speech systems will be discussed.
The effects of training on intelligibility of synthetic speech: II. The learning curve for synthetic speech
Authors: Nusbaum Howard C. , Schwab Eileen C.
Published: October 2005

This paper presents the second part of a report on the changes in intelligibility of synthetic speech produced by training. Two groups of subjects received training between the pre-test and post-test assessments of the intelligibility of the Votrax Type-N-Talk system. One group was explicitly trained on the synthetic speech. The second group received the same training procedures with natural speech. During training, subjects were presented with isolated words, meaningful and anomalous sentences, and prose passages. On each trial for words and sentences after identifying the stimulus, subjects were presented with feedback of a visual presentation of the stimulus and a second auditory presentation. For the first prose passage, subjects were given a printed version to read during auditory presentation of the passage. Subjects listened to three other passages without a printed version and then answered comprehension questions. Accuracy of word identification and response latency and accuracy to comprehension questions were recorded. Based on these data we will discuss the time-course of learning to perceive synthetic speech more accurately.
The Riverbank years of Hale J. Sabine
Authors: Kopec John W.
Published: October 2005

Once again the files at the Riverbank Acoustical Laboratories in Geneva, Illinois provided various insights to an extraordinary career in acoustics involving another member of the Sabine family—Hale Johnson Sabine. While researching the files for information pertaining to Professor W. C. Sabine [J. Acoust. Soc. Am. 69, L. Beranek, J. Kopec (1981)], and the forthcoming Paul E. Sabine story, various reports, papers, notes, and references involving Hale J. Sabine would surface. When compiled they disclosed his involvement in a wide spectrum of acoustical related activities at Riverbank from 1919 until 1961. Also included are accounts of Hale Sabine's continuing association with Riverbank until his death in the fall of 1981.
“Trapping” sound; the early development of commercial sound absorbents
Authors: Yerges Lyle F.
Published: October 2005

Almost 75 years of research and development of commercial acoustical absorbents have brought about a billion-dollar industry which produces products which are essentially refinements of the original fabrics and hair-felts first used to “trap” sound in buildings. The original producers of the various boards, blankets, and tiles used for sound absorption are all still in business, producing improved and more versatile products, and at prices remarkably comparable with those of more than one half-century ago. The pioneer work of Sabine, Norris, Mazer, and others will be reviewed; and the development of test procedures and performance standards will be discussed.
New methods of measuring normal acoustic impedance
Authors: Wayman James L.
Published: October 2005

In recent years new methods based on signal processing techniques have been developed to measure the normal acoustic impedance of materials. These methods prove to be considerably faster and easier to implement than the old Standing-Wave-Ratio technique that they replace. The hardware, software, and mathematical aspects of these techniques will be discussed and results obtained over a frequency range of 200 to 4000 Hz for several architectural materials will be shown.
Discrimination of stationary and revolving targets by the FM bat, Eptesicus fuscus
Authors: Zhang Weiping , Jen Philip H.-S.
Published: October 2005

Four FM bats, Eptesicus fuscus, were trained to use their echolocation ability to discriminate a revolving target and a stationary target that were randomly and simultaneously placed in the directions of two of a three-ramp platform. The bat-to-target distance ranged from 30 to 100 cm. The target was of semicircular shape with a radius of 16 mm and was made of thin copper plate of 0.05 mm. During the test, the frequency of a bat's approach to either target was recorded at each bat-to-target distance. Such a study revealed that a bat approached a revolving target more often than a stationary one. During the test, echolocation sounds emitted by three bats were recorded at bat-to-target distances of 40 and 80 cm. Analysis of these sounds revealed that there was no obvious difference in signal duration, interpulse intervals, or frequency contents among these sounds. A partial lesion was made electrolytically in the right hemisphere of the cerebellum of one bat. However, our study showed that such a partial lesion did not affect the bat's discrimination ability or the signal parameters of its emitted sounds. [Work supported by NSF 80-07348 and USPH 1-K04-NS00433 to Philip H.-S. Jen.]
Dynamic cues in binaural perception
Authors: Bachorski Stephen J. , Stern Richard M.
Published: October 2005

In recent years there has been renewed interest in the perception of stimuli with time-varying interaural time delay, intensity difference, and correlation. The results of most of these studies indicate that the binaural system loses its ability to process time-varying spatial images when the modulation rate of these interaural cues exceeds a few Hz. The position-variable model of subjective lateral position [R. M. Stern and H. S. Colburn, J. Acoust. Soc. Am. 64, 127–140 (1978)] can be extended to accommodate stimuli with time-varying interaural differences by forming time varying estimates of lateral position from interaural coincidences in auditory-nerve activity, with greater weight applied to more recent neural events. The extended model is similar to the classical running crosscorrelation theory, but it is based on the crosscorrelation of hypothetical neural activity rather than the stimuli themselves. In this paper we present predictions of the model for the subjective laterality of time-varying stimuli. We also compare predictions and data for discrimination and detection experiments, assuming that judgements are made on the basis of samples of the perceived lateral position and that performance is limited by the intrinsic variability of auditory-nerve activity. [Supported by NIH.]
Masking-level differences for trains of clicks
Authors: Dye R. H. , Yost W. A.
Published: October 2005

The detectability of masked click trains was measured under homophasic (NoSo) and anitphasic (NoSπ) conditions as a function of the number of clicks (n = 1,2,4,8,16,32) in the train and the interclick interval (ICI = 2,5,10 ms) between the clicks. The clicks were bandpass filtered at 2 kHz and presented against broadband noise (5 kHz, low pass). The 3-dB decline per doubling of duration usually found for antiphasic conditions [e.g., D. McFadden and A. D. Sharpley, J. Acoust. Soc. Am. 52, 574–576 (1972)] can be accounted for on the basis of energy detection or on the basis of optimal integration of samples of interaural differences of time and intensity between the S + N resultants at the two ears. The purpose of the present study was to measure MLDs under conditions for which optimal integration of interaural cues does not occur (short ICIs). Our results show that the slopes of the threshold versus n functions do not change with ICI, with the MLD remaining nearly constant across conditions. From this we conclude that the decline in threshold with duration (or n) for NoSπ is most consistent with energy detection and cannot easily be accounted for on the basis of integration of samples of interaural differences.
Bandwidth of three-element patterns and its effect on relative ear advantages
Authors: Lauter Judith L.
Published: October 2005

Since the earliest use of dichotic listening to measure performance differences in the two ears, the question of the influence of sound characteristics on the observed ear advantages (EA's) has been of central concern. In recent experiments studying the interactions between individual differences and sound characteristics, preliminary evidence for the importance of such characteristics as event timing, multi-dimensional temporal changes, and bandwidth has been found. We have designed a stimulus set for studying the effect of three-element pattern bandwidth on relative ear advantages. Three-element patterns-(6AFC), some made with filtered noise bursts, others with complex tones, have been tested on a number of subjects, for identification with contralateral interference [cf. J. L. Lauter, J. Acoust. Soc. Am. Suppl. 69, S22 (1982)]. Patterns or relative ear advantages indicate that as bandwidth in the patterns increases (e.g., comparing patterns made with tenth-octave noise bands versus patterns of third-octave noise bands), performance increasingly favors the right ear. It is suggested that this sensitivity of ear differences to stimulus bandwidth may contribute to the ear advantages observed for some speech sounds.
Dichotic temporal order judgment for long duration stimuli differing in stimulus microstructure and intensity
Authors: Hughes L. F. , Miller C. J. , Rafferty E.
Published: October 2005

Temporal order judgments were determined for dichotically presented speech and speech-eveloped noise stimuli. Stimulus onset asymmetries of 3, 6, 9, 20, 40, and 60 ms were factorially combined with intensity disparities between the ears of 0, 4, 8, and 16 dB. Naive subjects were instructed to indicate which ear was stimulated first. Hit and false alarm rates were obtained for each subject in each condition. Results contrasted with published nonmonotonic data (H. Babkoff, Percept. and Psychophys. 27, 273–275 (1980)], in that the difference between the normal deviates for hit and false alarm rates was a monotonic function of stimulus onset asychrony regardless of intensity desparity or stimulus type. The data were further analyzed in terms of the type of stimulus used, intensity imbalances between channels, ear differences, and stimulus onset asynchrony. Results will be discussed in terms of sensitivity and PSE measures for the foregoing factors.
Predicting frequency selectivity in forward masking from simultaneous masking
Authors: Lutfi Robert A. , Kistler Doris J.
Published: October 2005

Measures of frequency selectivity from forward masking indicate sharper tuning than those from simultaneous masking (Houtgast, 1974; Moore, 1978). We show that a simple relation between forward and simultaneous masking predicts this result. Consider the masking of a 10-ms, sinusoidal signal of frequency fs = 2.0 kHz by a 200-ms, 50-Hz-wide narrow-band noise masker with center frequency fm. Let Df = fm − fs be the frequency interval between the signal and the masker, and let Dt = ts − tm be the time interval between their offsets. We may define the following three masking conditions: (1) on-frequency forward, Dt = 15 ms, Df = 0 Hz, (2) off-frequency simultaneous, Dt = 0 ms, Df = 200 Hz, and (3) off-frequency forward, Dt = 15 ms, Df = 200 Hz. Masking functions (signal intensity at masked threshold versus masker intensity) were obtained in each of these conditions. Our preliminary data indicate that the off-frequency forward masking function (F) is predicted reasonably well by the composite relation F = G(kH), where G is the on-frequency forward masking function, H is the off-frequency simultaneous masking function, and k is a constant. Predictions were equally as good for other values of Df, yielding the expected difference in tuning between simultaneous and forward measures.
Forward masking tuning curves with randomized masker frequencies
Authors: Shelton B. R. , Booth J. C.
Published: October 2005

Forward-masking psychophysical tuning curves broaden as the signal level is increased, and the detection of components remote from the nominal signal frequency is one of the mechanisms proposed to account for the observation [D. M. Green, B. R. Shelton, M. C. Picardi, and E. R. Hafter, J. Acoust. Soc. Am. 69, 1758–1762 (1981)]. It is reasonable to assume that the effectiveness of such a strategy would be maximized in the situation where the same signal and masker frequency is uncertain from one trial to the next. Tuning curves were obtained in 250-trial runs with maskers of 500, 750, 1000, 1250, and 1500 Hz either randomized from trial-to-trial or presented in five 50-trial blocks. The signal was a 1000-Hz tone of either 5 or 30 dB SL. The tuning curve broadened with the high signal level, but the randomization of masker frequency had little or no effect on the sharpness of tuning. Similar results have been reported for a simultaneous masking procedure [B. R. Glasberg, B. C. J. Moore, and R. A. Lufti, J. Acoust. Soc. Am. 72, 273–275 (1982)]. The data offer no support to the hypothesis that off-frequency listening can account for the broadening of psychophysical tuning curves with increased signal level. [Work supported by NSERC].
Measurement of adaptation effects using serial reaction times
Authors: Goldman Thomas M. , Weiler Ernest M. , Davis James M.
Published: October 2005

This investigation examined the use for a reaction time procedure to measure monaural auditory adaptation. Several studies using reaction times to a pure tone have demonstrated significant increases in latency after 7-min duration of a continued tone. In the present study, serial reaction times to tonal onset (400 Hz) were measured at regular intervals while the subjects were stimulated with a continuous (500 Hz) pure tone for 3 min. Although mean values indicate a change of response latency between baseline at 400 Hz and the first test in the presence of 500 Hz, there is no evidence of further significant change in latency. No evidence was found for cumulative adaptation of latency times.
A functional adaptivity basis for the mechano-neural transduction process in hearing
Authors: Adelman Roger A. , Weiler Ernest M.
Published: October 2005

A model for the mechano-neural transduction process which includes an adaptivity or tuning mechanism is presented. The adaptivity system is predicted on the role of inner hair cells as primary transducers whose action potential thresholds are modified by neighboring outer hair cells. The proposed mechanism finds basis in the neural anatomy associated with these structures and is consistent with the predominance of efferent terminations on outer hair cells and the predominance of afferent origins from inner hair cells. The adaptivity is functionally consistent with phychoacoustic demonstration of pitch and loudness discrimination as well as adaptive and fatigue behavior.
A comparison of detection thresholds obtained with forced-choice procedures and with a standard clinical procedure
Authors: Marshall Lynne , Jesteadt Walt
Published: October 2005

Detection thresholds, psychometric functions, and response criteria were measured for groups of younger and older normal and hearing-impared adults (total N = 72). Detection thresholds were obtained at 500 and 4000 Hz using a standard clinical procedure and a two-interval, forced-choice (2IFC) adaptive procedure. A measure of response bias was obtained using a yes-no procedure. Psychometric functions were obtained for all three procedures. The 2IFC adaptive thresholds were approximately 7 dB lower than standard clinical thresholds for all four groups of listeners. Data from the yes-no procedure indicated that all four groups were equally conservative. There was no correlation between the magnitude of the difference between adaptive and clinical thresholds and the degree of response bias. Psychometric functions for the forced-choice procedures were generally shallower than those for the standard clinical procedure and were shifted several dB to the left. Criterion effects do not appear to account for the difference between these psychometric functions or the difference between adaptive and clinical thresholds. [Work supported by NIH and UCR-UNO.]
Stepwise dependence of binaural loudness summation of interaural phase
Authors: Mulligan B. E. , Gleisner D. P.
Published: October 2005

Findings reported previously [B. E. Mulligan and L. S. Goodman, J. Acoust. Soc. Am. Suppl. 1 70, S106 (1981)] indicated a stepwise dependence of binaural loudness on interaural phase for 250-Hz tones presented in “quiet.” The step in loudness {for both monaural-binaural pairs of tones) was found to occur in the vicinity of the Hornbostel-Wertheimer constant (± 59°) on each side. Utilizing the same procedure, the present research extends these findings to tone frequencies of 500, 650, 1000, 1200, and 1400 Hz. Again the step was found to occur in the region of the Hornbostel-Wertheimer constant for 500- and 650-Hz tones (± 117° and ± 153°). However for frequencies of 1000, 1200, and 1400 Hz, the steps occurred at approximately ± 125°, ± 78°, and ± 31° respectively. These values corespond to the natural limits of confusion-free zones for tones of these frequencies. This suggests that binaural loudness may reflect a summative process which differentiates between tonal signals originating at angles of azimuth within and without confusion zones.
Computerized pulsed-ultrasound techniques for the measurement of lingual, laryngeal, and lateral pharyngeal wall movements
Authors: Ostry David J. , Munhall Kevin G. , Parush Avraham
Published: October 2005

Keller and Ostry (J. Acoust. Soc. Am., in press) described a microcomputer-based system for the measurement of tongue dorsum movements with pulsed-echo ultrasound. We have recently completed an upgrade of this system to provide facilities for (1) simultaneous ultrasound measurement of any two of lingual, larygeal, and lateral pharyngeal wall movements, (2) the transduction of jaw movements and force. (3) concurrent EMG sampling, and (4) acoustic sampling at rates up to 7 kHz. The presentation focuses on the pulsed-ultrasound recording, display, and analysis techniques. The transducer placement procedures for tongue dorsum, vocal folds, and lateral pharyngeal wall are described and several examples of simultaneous recordings are presented. Data analysis techniques involving separate application of natural cubic spline functions to each of the records are also presented and an iterative procedure for optimizing goodness of fit of the spline functions is described.
Motor control of laryngeal articulation
Authors: Löfqvist Anders , McGarr Nancy S. , Honda Kiyoshi
Published: October 2005

Differences have been reported on the contributions of the intrinsic laryngeal muscles for the control of voicing and glottal aperture. Although glottal abduction/adduction in single voiceless consonants appears to be controlled by PCA and INT, our previous work has shown that variations in glottal aperture during voiceless consonant clusters can be controlled by PCA alone. The present experiment examined electromyographic recordings of four intrinsic laryngeal muscles (INT, LCA, VOC, and CT). Transillumination was used for recording glottal opening. The results of the present study indicate that glottal opening in voiceless consonant clusters is also controlled by the VOC, while INT, LCA, and CT tend to remain inactive. The CT is also active for voiceless consonants; this activity might be associated with the cessation of voicing. A high correlation was found between size of maximum glottal opening and speed of glottal adduction in voiceless sounds. This result implicates a significant passive component in glottal adduction. [Work supported by NINCDS.]
Analysis of tongue motion during swallowing using real-time ultrasound visualization
Authors: Sonies Barbara C. , Shawker Thomas H.
Published: October 2005

Because real-time ultrasound provides an excellent method to visualize the soft tissue structures of the tongue during speech, this technique was applied to analyze the oral and pharyngeal stages of swallowing. Eight normal subjects (ages 19–26, x̄ − 22.7] and one patient with a neurologic disease were subjects. Sagittal ultrasound scans of the tongue were obtained while subjects swallowed 5 cc of water in single swallows. Measurements were made of mid-tongue thickness at rest and during swallow, tongue length, sequence and timing of bolus movement, and tongue activity during swallow. Comparison of data for the normal and impaired subjects will be presented along with a discussion of the stages of swallowing. The results will be discussed with respect to neuromuscular theory and standard radiologic techniques.
Rating of impulse noise, in particular shooting noise, with regard to annoyance
Authors: Smoorenburg G. F. , Vos J.
Published: October 2005

For impulsive noises ISO 1996 on “Assessment of noise with respect to community response” proposes to apply a penalty of 5 dB to the equivalent level Leq of the noise. In 1977 we tentatively concluded on the basis of the literature that the rating sound level (Lr, as defined in ISO 1996) for impulse sounds separated by relatively silent periods can be obtained from Lr = Limp + 10 log N − 42, where Limp = level of a single impulse, A-weighted, 35-ms integration time and N = number of impulses per day. This formula implies a penalty of about 12 dB to Leq of the noise. In two laboratory studies we found that the ratings for traffic noise at Leq = 45–50 dB(A) equaled those for shooting noise and pile driving noise both at about a 12-dB-lower Leq. A subsequent study, in which we included background noise at 35 and 55 dB(A), showed that ratings for traffic noise presented at a level 5 to 10 dB above the background equaled those for shooting noise at an equivalent level 10 dB below the level of the traffic noise. These laboratory studies support the application of a 10- to 12-dB penalty to the Leq of impulse noise from shooting or pile driving.
Wind noise reduction in blast noise measurement
Authors: Wagner Mark
Published: October 2005

Wind-generated noise presents a major obstacle in outdoor blast noise measurement. Research in the area of microphone windscreening is sparse and tends to be empirical at best. A microphone system will be described which attacks the wind noise problem from two directions: first, the system uses a windscreen which has been optimized for rejection of low-frequency wind noise, and second, a multimicrophone signal processing system is used to discriminate between acoustic signals and wind-induced noise. Performance data on a prototype system will be presented.
Sound absorption in aqueous mixtures of MgSO4-HCl and MgSO4-H2SO4
Authors: Fisher F. H.
Published: October 2005

An analysis is made of the Kurtze and Tamm acoustic absorption data in MgSO4-HCl and MgSO4-H2SO4 aqueous mixtures. The reduction in absorption as acid is added to a 0.05 MgSO4 solution cannot be explained on the basis of ion-pairing alone. However, these apparently different sets of data for each acid-MgSO4 mixture can be analyzed on a common basis. The results are explained empirically in terms of normal mode kinetic coupling of volume changes between the MgSO4 and HSO4− dissociation reactions as a function of free hydrogen ion concentration.
Phonological short-term memory preserves phonetic detail
Authors: Mattingly Ignatius G. , Studdert-Kennedy Michael , Magen Harriet
Published: October 2005

If phonological short-term memory preserves phonetic detail (as would seem necessary if listeners are to correct misperceptions on the basis of later information), a sequence of words in different dialects might be difficult to recall, because phonological redundancy could not be exploited. Five women (one Scottish English, one ESL with Italian interference, three GA speakers) recorded the digits one, two⋯ten. From these we compiled 20 pseudo-random, 12-word single-talker sequences, 20 three-talker same-dialect (GA) sequences, and 20 three-talker, mixed-dialect (GA, SE, ESL) sequences. Serial order recall by 18 female GA speakers was tested. Recall of single-talker sequences was not reliably better if talker and listeners shared dialect (GA), nor did recall of of later words in a sequence vary systematically with sequence-type. But earlier words were better recalled in three-talker, same-dialect than in three-talker mixed-dialect sequences, both for all words and for GA words common to both sequence-types. Implications for the role of phonetic storage in normal listening will be discussed. [Supported by NICHD and NSF.]
Species differences in neural lateralization of species-specific calls
Authors: Petersen Michael R.
Published: October 2005

Petersen et al. [Science 202, 324–327 (1978)] reported that Japanese macaques exhibited a right ear advantage (REA} when listening to a semantically distinctive feature of their vocalizatioos. Several heterospecific monkeys tested in identical conditions with the Japanese monkeys' calls failed to show any reliable ear advantage. However, recent studies with humans have shown that the size and/or direction of ear advantages vary with the physical feature to which subjects attend. This raised the question of whether the species differences in lateralization obtained in our setting represented (1) a processing difference for the same signal feature or (2) a difference between species in the signal feature to which they attended. To choose between those alternatives we ascertained whether Japanese and heterospecific monkeys were in fact attending to the same acoustic feature when they showed their respective patterns of lateralization. Two Japanese and two heterospecific monkeys received extensive training on a discrimination task that required them to classify 15 vocalizations into two categories. During this time the Japanese monkeys exhibited REA's but the heterospecifics showed no ear advantage. The animals were then tested for generalization to 25 novel, natural vocalizations and six synthetic calls. These tests revealed that all four animals were attending to the same feature of the Japanese monkey calls. The animals were then returned to the original training stimuli and they exhibited their earlier patterns of lateralization. Thus this study shows that even when attending to the same physical feature, Japanese and heterospecific monkeys employ different neural processing strategies. This suggests that the communicative valence of the signals used in testing may account for the lateralization differences observed between species. [Work supported by NSF. Deafness Research Foundation and Sloan Foundation.]
Irreversible thermodynamics formulation of multiple relaxation processes, with application to laser-generated sound in 4 °C water
Authors: Pierce Allan D.
Published: October 2005

An irreversible thermodynamics formulation for a fluid with an arbitrary number of internal coordinates leads to an inhomogeneous wave equation for acoustic pressure with source term, −(β/cp) ∂q/∂t − (K/cp)∂2q/∂t2. Here β is coefficient of thermal expansion, q is heat added per unit time and volume, and K is a constant of the order of 10−11 s/°C which is related to the relaxation time matrix. The theory explains the tripolar pressure pulses observed by Hunter et al. [J. Acoust. Soc. Am. 69, 1563–1567 (1981)] following irradiation of 4 °C water (for which β = 0) by short laser pulses. A precise evaluation of K follows from analysis of reported waveforms. If water has only a single relaxation process, the magnitude of K is at variance, however, with the Hall structural relaxation theory of bulk viscosity, for which the estimated relaxation time is of the order of 10−12 s. The conflict is resolved if water has a second relaxation process that has negligible influence on absorption and wave speed, but which substantially influences β. The relaxation time for this newly inferred process may be as long as 10−6 s. [Work supported by ONR.]
The measurement of sound propagation from an elevated source
Authors: Raspet R. , Schomer P. D. , Hottman S. D.
Published: October 2005

Accurate source characterization and sideline decay prediction is necessary for assessing the environmental impact of rotary wing aircraft. Analysis of aircraft flyby sound level data indicates that atmospheric refraction can have a significant effect on the measured sound levels at longer slant distances [R. Raspet, J. Acoust. Soc. Am. Suppl. 1 70, S68 (1981)]. We have begun a measurement program to investigate the effect of atmospheric refraction on the sound levels from an elevated source for a variety of meteorological conditions. In this paper we will describe the physical layout of our experimental range, the experimental design, and instrumentation used. Prime consideration in the design are (1) simultaneous sound level and meteorological measurements; (2) reduction of wind noise so that measurements can be performed under all wind conditions; (3) sufficient sampling of the sound field at each distance so that the level measured represents an average level received in the region of the ground.
History and some applications of digital signal processing
Authors: Gold Bernard
Published: October 2005

Digital signal processing started to become a discipline about 20 years ago, although its roots go much further back. The spark that generated the ensuing great activity was the realization that digital computer technology was on the verge of great leaps forward in both speed and miniaturization. This made it possible to predict that traditional analog processing devices such as filters and spectrum analyzers would become digital and result in big improvements for many applications. Acoustic signals such as speech, seismic, and sonar signals were prime candidates for digital processing because of their relatively low bandwidths. A brief history will be presented of the development of this field, and its subsequent inclusion in electrical engineering curricula. Controversy still exists on how this new entry should be treated academically, and that subject will be discussed. Several applications to the field of speech communications will be considered and a series of audio recordings will be played to help illuminate these applications. [Work sponsored by Department of the Air Force.]
Auditory and phonetic processing of speech: Adaptation, anchoring, and contrast
Authors: Sawusch James R. , Mullennex John
Published: October 2005

Three different experimental procedures were used to assess the relative contributions of auditory and phonetic coding processes in speech perception. Synthetic and natural [spa] syllables were used in conjunction with a synthetic [ba]-[pha] test series. The [spa] and [ba] syllables had virtually identical effects as adaptors in a selective adaptation procedure, indicating an auditory locus for adaptation effects. In the paired-comparison procedure, [spa] and [pha] syllables produced similar effects on an ambiguous test item, indicating that phonetic processes mediated these results. Finally, in an anchoring procedure, the inclusion of a [spa] syllable as an anchor in the [ba]-[pha] series produced results that were intermediate between the adaptation and paired-comparison results. Thus results with the anchoring procedure seem to reflect both auditory and phonetic coding processes. The implications of these results for models of speech perception and the nature of phonetic coding will be discussed. [Work supported by NIMH.]
A shared mechanism for perceiving and producing voice-onset times in speech
Authors: Gordon Peter C. , Meyer David E.
Published: October 2005

A reaction-time method was employed to assess the relationship between speech perception and production mechanisms at the level of phonetic features. Subjects memorized a set of CV syllable pairs so that they could respond to the stimulus syllable of a pair by saying the corresponding response syllable. With acoustic presentation of the stimuli, response latencies depended on the phonetic relationship between the stimuli and the responses. Shared voice-onset time facilitated the response but shared place of articulation had no effect. This facilitation did not occur with visual presentation of the stimuli, indicating that it was due to speech perception priming speech production and not due to the ease of memorizing different syllable pairs. Similar results were found for different consonant types (stops and fricatives) and for stimulus-response combinations containing different vowels. These findings partially confirm classic views of the relationship between speech perception and production, such as those assumed by the motor theory of speech perception. It appears that speech perception and production may involve a shared voice-onset time mechanism. [Supported by NSF grant BNS-8206809.]
The b/w contrast and considerations of syllable duration
Authors: Maxwell Edith M. , Landahl Karen L.
Published: October 2005

Recent research suggests that a set of acoustic properties are ambiguous with regard to their categorization as /b/ or /w/ depending on the duration of the following vowel [J. Miller and A. Liberman, Percept. Psychophys. 25, 457–465 (1979)]. Such evidence causes difficulty for a theory of acoustic invariance [S. Blumstein and K. N. Stevens, J. Acoust. Soc. Am. 66, 1001–1017 (1981)], since identification of properties at the onset appears to be dependent on the context of later-occurring acoustic material. We repeated earlier experiments [J. Miller and A. Liberman, Percept. Psychophys. 25, 457–465 (1979)] with some variation. While maintaining continua of stimuli between /b/ and /w/, our stimuli were made more natural by manipulating the spectrum of voicing prior to consonant release. The consequence was weak prevoicing and an abrupt onset at the /b/ end, and stronger prevoicing and a gradual onset at the /w/ end. Results showed that the tendency for identification of mid-valued stimuli to be affected by the following vowel duration was reduced. These findings suggest that earlier results may be explained by the structure of the synthetic stimuli and by properties of auditory processing. [Work supported in part by NSF and by NINCDS.]
Perceptual equivalence of two acoustic cues for /r/-/l/
Authors: Polka Linda , Strange Winifred
Published: October 2005

The perceptual effects of orthogonal variations in two acoustic parameters which differentiate American-English prevocalic /r/ and /l/ were examined. A spectral cue (frequency onset and transition of F3) and a temporal cue (relative duration of initial steady-state and transitions off F1) were varied in synthetic versions of “rock” and “lock.” Four temporal variations (A, B, C, D) in each of ten stimuli of a spectral-cue continuum were generated. In phonetic identification and oddity discrimination tasks with the four series, systematic displacement of perceptual boundaries and discrimination peaks reflected a trading relation between the two cues. Utilizing the A and C series, the perceptual equivalence of spectral and temporal cues was investigated by comparing the relative discrimination of three types of stimulus comparisons: facilitating cues (values of both acoustic parameters were selected to facilitate phonetic differentiation), one-cue (only spectral cue values varied), and conflicting cues (values of both acoustic parameters were selected to conflict as to phonetic differentiation). As predicted, discrimination accuracy was ordered: facilitating cues > one-cue > conflicting cues comparisons, indicating that perceivers responded on the basis of an integrated phonetic percept. [Supported by NIMH.]
Memory for isolated vowels and for vowels in a consonantal context: An individual differences scaling comparison
Authors: Rakerd Brad , Verbrugge Robert R.
Published: October 2005

We have previously reported that an individual differences scaling comparison of the perception of isolated vowels and the perception of vowels in a consonantal environment (/dVd/) indicated the following: vowels are processed in a more linguistically appropriate way when they occur in consonantal context [B. Rakerd and R. R. Verbrugge, J. Acoust, Soc. Am. Suppl. 1 71, S76 (1982)]. In the present investigation, the method of that earlier experiment was extended to a study of vowel memory. Subjects were asked to make similarity judgments about their memories of (a) isolated vowels, or (b) vowels in /dVd/ consonantal context, and the resulting similarities matrices were submitted to nonmetric individual differences scaling. The scaling analysis indicated (1) that vowel memory, like vowel perception, is to a measurable degree organized around the features of advancement, height, and tenseness; and (2) that the previously reported perceptual influence of consonantal context is largely to be explained in terms of the stimulation that was presented to perceivers, rather than in terms of any sort of knowledge that perceivers brought to bear in perceptual processing. [Research supported by NIH grants HD01994 and RR05596.]
A study of two-formant models for vowel identification
Authors: Paliwal K. K. , Lindsay D. , Ainsworth W. A.
Published: October 2005

An experiment has been performed where various two-formant vowel models reported in the literature were assessed as to their ability to predict the formant frequencies obtained in a vowel identification task. An alternative model is proposed in which the auditory processing of vowel sounds is assumed to take place in two stages: the peripheral processing stage and the central processing stage. In the peripheral processing stage, the speech spectrum is transformed to its auditory equivalent and the frequencies of the first three formants are extracted from this spectrum, using the peak-picking mechanism. The central processing stage performs a two-formant approximation. The first and second formant frequencies of the two-formant model are taken to be equal to the first and second formant frequencies extracted at the peripheral processing stage plus a perturbation term which accounts for the interaction effects of the neighboring formants. The perturbation caused by each of these neighboring formants is inversely proportional to its separation from the main formants. This model compares favorably with previous models in its prediction of the formant frequencies obtained from the vowel identification task.
A cross-language study of the perception of nasal vowels
Authors: Hawkins Sarah , Stevens Kenneth N.
Published: October 2005

Nasalization of vowels introduces one or more additional resonances in the vicinity of the first formant (F1), and often a shift of F1. The perceptual effect of these types of spectral changes has been studied for five vowels, [i e ɑ o u], synthesized in the context [tV]. Identification and discrimination functions were obtained for syllables forming an acoustic continuum from a non-nasal to a nasal vowel. Identification functions showed rather abrupt shifts from non-nasal to nasal judgments, and discrimination functions tended to peak near the boundaries. These effects were less marked for speakers of English than for speakers of certain Indian languages containing the nasal-non-nasal opposition. We have attempted to specify some common acoustic correlate of the feature nasal, associated with a reduction in prominence of the F1 spectral peak, that would account for this shift in perception. Proposals are made for describing how the auditory system responds to different degrees of low-frequency prominence, either through spectral or temporal characteristics of peripheral auditory processing. [Supported by a grant from NINCDS.]
RANDI II—An ambient noise model that includes coherent hydrophone summation for sonar system performance and signal processing in shallow and deep water
Authors: Wagstaff Ronald A. , Hamson Rachael M.
Published: October 2005

The Research Ambient Noise Directionality II (RANDI II) model is described which predicts noise levels and directionalities in specified environmental/shipping conditions and calculates the response of any arbitrary array of hydrophones to the noise field. The model includes a shallow water option based on normal mode propagation. The array response per ship is calculated by the addition of the complex pressure of individual modes at each hydrophone followed by either coherent or incoherent summation of the modes. Shallow water wind noise is provided by a wave theory model for the correlation matrix between all hydrophones of the array. Modeled results are compared with measured data at three different sites, one in shallow water. The agreement is excellent.
Array beam noise characterization
Authors: Heitmeyer R. M. , Davis L. , Yen N.
Published: October 2005

The formulation of the stochastic process for beam noise of a horizontal array operating at low frequency is analyzed based on the array's response to the distant ship-induced noise field. The general form of beam noise characteristic function obtained with nonhomogeneous compound Poisson process assumption for shipping distribution is related to three major operation environment parameters: the mean number of shipping density, the array aperture length and beam pattern, and random fluctuation and range dependence in the transmission loss function. This characteristic function can be used to derive the probability of observing low noise region in terms of frequency-azimuth-time representation of noise surface for some specific operation scenarios. Computer modeling for ship lane dominant noise field and uniform shipping distributed noise field are performed for investigating the sensitivity of the relevant parameters to the array's beam noise statistical property.
The occurrence of low beam noise level in ship induced noise field
Authors: Heitmeyer R. M. , Yen N. , Davis L.
Published: October 2005

The formulation of the stochastic process for beam noise of a horizontal array operating at low frequency is analyzed based on the array's response to the distant ship-induced noise field. The general form of beam noise characteristic function obtained with nonhomogeneous compound Poisson process assumption for shipping distribution is related to three major environmental parameters: the mean number of shipping density, the array aperture length and beam pattern, and random fluctuation and range dependence in the transmission loss function. This characteristic function can be used to derive the probability of observing low noise regions in terms of frequency-azimuth-time representation of noise surface for certain acoustic environments. Computer modeling for ship lane dominant noise field and uniform shipping distributed noise field were performed for investigating the relationship among the relevant parameters in the array's beamforming output. The results illustrate the sensitivity of beam noise statistical characteristics to the angular ship density.
Analysis of acoustic ambient noise data for Monterey Bay, California
Authors: Elles C. J. , Wilson O. B.
Published: October 2005

Analysis has been carried out of sonobuoy noise data recordings made in Monterey Bay at various times during 1980 and 1981 by Wilson, Wolf, and Ingento, Calibrations permitted reducing sound pressure spectrum levels to a standard reference level. The dependence of levels upon range from shore as a function of wave and surf conditions was investigated over the frequency from 10 to 2500 Hz. During heavy wind and surf conditions, levels are significantly higher than corresponding levels typical of the deep ocean, such as from the Wenz curves. At frequencies in the range 100–500 Hz, the decrease in levels with increasing range from shore and their increase with increasing swell wave energy support the conclusion that waves breaking at the beach can contribute significantly to the ambient noise in coastal waters. [Supported in part by funds from the Naval Research Laboratory.]
Passive localization of sounds from bowhead whales, Balaena mysticetus: Spring migration off Point Barrow in 1982
Authors: Ellison William T. , Cummings William C. , Holliday D. V.
Published: October 2005

The purpose of this field expedition was to determine if acoustic techniques could be used to assist in conducting a census of the bowhead population during its eastward spring migration past Point Barrow, Alaska. A three-hydrophone triangular array was established at the edge of the shore past ice off Point Barrow, Alaska in May 1982. The two base legs of the array were 988 and 1486 m in length with a vertex angle of 172.8°. The longest leg was oriented 44.7 °T and the short leg 231.9 °T. Over 7500 bowhead whale sounds were recorded during the period 3–17 May 1982. Localizations based on arrival time differences were developed from 145 sounds recorded during a 2-day period of high sound activity, 8–9 May. These localizations revealed some whales to be beyond an observer's maximum visual range. A 2-min film clip showing field contributions and whale sightings will be presented. [Work supported by North Slope Borough, Alaska.]