bluuebunny/crossref_metadata_2025 huggingface dataset:
Summating potentials during and following acoustic trauma
Authors: Durrant J. D.
Published: October 2005

Differential recording electrodes were utilized in the guinea pig to determine to what extent the SP reflects the adverse effects of overstimulation, specifically when the frequency of the exposure stimulus is near the best frequency of the recording site (viz., 750 Hz, turn III and 10 kHz, turn I). Data from the first turn concerning the DIF− (SV-ST) component suggests that, to a considerable extent, the behavior of the SP during and following traumatic sound stimulation (typically 120 dB for 15 min) corresponds favorably with that of the cochlear microphonic and, thus, may be accounted for by a simple reduction in hair-cell output. The SP, like the CM, exhibits greater amounts of reduction (proportionally), when elicited at sound pressure levels at which the CM input-output function is linear, and less suppression at levels in the bend-over region. DIF SP recorded in the third turn and recordings of the AVE+ or common mode component [(SV + ST/2)] reflect somewhat more complex trends which perhaps reflects changes in the electrical properties of the cochlear partition. This contention is supported by observed changes in the endocochlear potential during and following exposure. It is concluded that hair-cell sensitivity, while clearly important, is not the sole determinant of the electrophysiological manifestations of acoustic trauma and that the most complete description of hair-cell function is achieved only when both the SP and CM are recorded. [Supported by DRF.]
Categorizing hearing loss from speech recognition data
Authors: Corliss Edith L. R. , Moore Elizabeth F.
Published: October 2005

During the National Health Survey of 1971–1973, pure-tone threshold measurements were made for octaves from 500 to 4000 Hz. At the same time, subjects were presented with lists of test sentences, and scores were kept identifying the individual words missed. Initial presentation of the test material was keyed to the subject's hearing level at 1000 Hz, and if more than a few words were missed, the level of successive test lists was raised in 10-dB increments until a high score was achieved or the maximum level of 80 dB for the list presentation was reached. By classifying the individual phonemes of each word and grouping the test results for each list, growth functions for intelligibility were derived for each ear of every subject who received more than a single list for each ear. The results show distinct groupings of slope of growth function and intercept along the level of list presentation, separating classic cases of “recruitment,” sensorineural loss, and conductive losses. The categorization permitted separate consideration of low-frequency, midfrequency, and high-frequency losses.
Laterization and the MLD: detection-threshold performance of an auditory-nerve-based model for lateral position
Authors: Stern Richard M.
Published: October 2005

Predictions of a binaural-interaction model featuring a description of subjective lateral position are compared to detection-threshold measurements using interaurally time-delayed and amplitude-shifted tonal targets and broadband maskers. Position predictions of the model are obtained by nonoptically weighting interaural comparisons of auditory-nerve firing times, as described previously [R. M. Stern, Jr., J. Acoust. Soc. Am. 59, S23 (A) (1976)]. Detection predictions are obtained, assuming that judgments are made on the basis of a single position estimate for each stimulus, and that internal noise is caused by the randomness of the auditory-nerve patterns. Although the model had successfully described the results of most lateralization and discrimination experiments, its predictions are in contradiction to the observed joint dependence of detection thresholds on the interaural time and intensity differences of the masker. It is suggested that detection thresholds are more accurately described by a model that makes judgments on the basis of stimulus attributes other than lateral position. This conclusion is compared to the results of previous studies of binaural-detection performance with interaurally-identical broadband maskers. [Work supported by NIH.]
Subjective sound quality of all-pass networks
Authors: Milner Paul , Bauer Benjamin B.
Published: October 2005

In an earlier study [J. Acoust. Soc. Am. 54, 334 (1973)] we reported that the subjective quality of music appeared to be unaffected by processing signals through all-pass phase-shift networks as used in the SQ quadraphonic matrix encoding system. These conclusions were based on the results of a same/different experiment in which the listeners appeared to be operating at a chance level for a two-alternative forced-choice paradigm. They responded with an equal likelihood (50%) of same and different regardless of the nature of the stimulus pairs. Additional experiments have been performed with speech samples using several lists of Harvard PB Sentences. In a same/different experiment, the listeners overwhelmingly judged “same” regardless of conditions. However, in an A-B-X experiment, the listeners favored the “B” choice, the one nearest the time to the unknown. Foil conditions of high-pass filtering, low-pass filtering, and peak-clipping were included to verify the performance of the listeners. Correct responses to these conditions were provided except at near discrimination thresholds. One may therefore conclude that such all-pass networks have no audible effect on subjective quality. In addition, whe presented with a difficult A-B-X discrimination task, a significant response bias results from a preference to the stimulus closest in time to the unknown.
Recognition and detection of pure tone
Authors: Green David M. , Weber Daniel L. , Duncan Joseph E.
Published: October 2005

We report measurements of the relation between the detection and recognition of sinusoids of different frequencies. The motivation for these measurements was a theorem presented by S.J. Starr, C.E. Metz, L.B. Lusted, and D.J. Goodenough [Radiology 116 533–538 (1975)] The theorem related recognition performance to a transform of the area under the detection ROC curve. They tested these predictions in a visual experiment, we tested these predictions in a noise masking experiment using sets of sinusoidal signals of four and two frequencies. In this latter case frequency separation was systematically varied to violate the theorem's assumptions concerning orthogonality. Except for the very small frequency separation (20 Hz). the theorem provided reasonably good predictions of the recognition data. [This research was supported in part by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Temporal processing of paired clicks: monaural and binaural summation at threshold
Authors: Bruder G. E. , Yozawitz A. , Sutton S.
Published: October 2005

The threshold reduction that results from presenting the second of two equally intense clicks to either the same or the other ear after a brief interval (Δt) was measured using a three-interval forced-choice technique. The difference between thresholds for single clicks and click pairs randomized in the same session were measured monaurally for nine listeners and binaurally for 15 listeners. Summation of either monaural or binaural clicks was consistently less than would be predicted by a model of perfect energy summation, which concours with other studies using noise bursts of variable duration. The threshold reduction for a pair of monaural clicks was 2 dB at a Δt of 2 msec and even smaller reductions were obtained at longer Δt's. The threshold reduction for a pair of binaural clicks was 1.5 dB at interaural Δt's ranging from 0.01 to 15 msec. At Δt's ranging from 30 to 200 msec the threshold reductions for both binaural and monaural click pairs agreed with the level predicted by Green and Swets's “integration model” for the case of two independent observations.
Some properties of narrow-band high-frequency waveforms
Authors: Colburn H. S.
Published: October 2005

Since waveforms whose spectra are limited to frequencies above 2000 Hz have been used extensively in recent binaural experiments, we decided to generate waveforms of this type, to filter them through critical-band-like filters, and to study the properties of the resulting waveforms with some simple visual displays. For binaural processing, interaural comparisons between envelopes and carriers of two monaural waveforms are especially relevant as are the effects of the interaural relations of component waveforms (as in a binarual detection stimulus, for example) on the interaural differences in the total waveforms. We believe that people who use narrowband waveforms in experimental or theoretical studies should understand them on both a mathematical and an intuitive level. Our displays should be helpful in both these areas. [Work supported by NIH.]
Discrimination of a moving auditory “dot” from a stationary auditory “line”
Authors: Grantham D. Wesley , Wightman Frederic L.
Published: October 2005

In order to assess the binaural system's ability to detect varying interaural temporal differences (IATD's) we required observers to discriminate a binaural noise with a sinusoidally modulated IATD (a “moving dot”) from a binaural noise with random static IATD's (a “stationary line”). This latter stimulus was constructed so that its image presumably filled the same intracranial space as that described by the excursions of the “dot.” For several modulation frequencies (fm) from 0 to 200 Hz we determined the peak IATD (Δtmax, corresponding to the extent of movement) required for 75% discriminability of the dot from the line. As fm increased from 0 to 50 Hz, threshold Δtmax increased from 30 to 130 μsec, reflecting the decreasing ability of the binaural system to follow the fluctuating IATD's (forfm > 50-Hz thresholds decreased again, probably because cues other than movement were available at these high rates of modulation). A simple extension of the Jeffress coincidence network model for localization is proposed as a possible “movement detector.”
Recovering decision latency distributions from reaction time experiments
Authors: Burbeck S. L.
Published: October 2005

Reaction times (RT's) involve residual delays due to physical inertia and neural transmission latencies, as well as a decision latency. If the residual and decision latencies are independent additive stages, as is widely assumed, then the observable distribution of RT's is the convolution of the un-observable distribution of decision latencies with that of residual latencies. RT to the offset of a 70-dB SPL wide-band noise was used to estimate the residual distribution for each observer under the assumption that decision latencies approach zero for loud signals. RT distributions were also collected using the offset of weak (P/N0 = 23 and 25 dB) 3000-Hz tones in wide-band noise. Estimates of the decision distributions were obtained using Fourier methods [D. M. Green, Behav. Res. Meth. & Instrum. 3, 121–125 (1971)] to deconvolve the estimated residual distributions from the weak signal distributions. The results appear to be valid distributions, supporting the independent additive stage assumptions. [Work supported in part by NSF.]
Annoyance produced by aircraft noise: relationship to fear of overflights and general anxiety
Authors: Vanderhei Moran Sharon , Loeb Michel
Published: October 2005

It has been suggested that expressions of annoyance attributable to aircraft noise may reflect in part fear of aircraft overflights and possible crashes. If this is true, then residents of areas where crashes have occurred should express more annoyance. To test this hypothesis, 50 residents of an Albany, New York area where an aircraft crash producing fatalities recently occurred and 50 residents of a comparable nearby area without such a history, were asked to respond to a “Quality of Life Questionnaire.” Among the numerous items on it were items designed to test annoyance by noise and fear of aircraft overflights. It was predicted that those in the crash area would express more annoyance and more fear and would more often identify aircraft as a noise source. These hypotheses were sustained. Intercorrelations of responses to items also suggest that generalized fears, annoyances, and anxieties may generate or modify annoyance by noise. [This research was facilitated by a grant between the University of Louisville and NASA.]
Research on tactile communication of speech
Authors: Durlach N. I. , Braida L. D. , Reed C. M. , Rabinowitz W. M.
Published: October 2005

We are interested in developing tactile communication displays for use by the profoundly deaf and the deaf blind. The approach we are taking involves a laboratory-based comparative study of various spectral and articulatory display schemes, including the Tadoma method of speech reading. We will conduct an informal discussion of issues related to our research, and in particular, to fundamental problems concerned with the choice of display schemes and the choice of training procedures. Examples of the types of questions that we intend to address are the following: (1) Is there any tactile display that can provide good speech communication? (2) What are the advantages and disadvantages of articulatory displays relative to spectral displays ? (3) How well can one estimate the ultimate potential of a given tactile display on the basis of experiments that involve only limited, laboratory-type training in the use of the display?
Role of implosive transitions in word perception
Authors: Streeter L. A. , Nigro G.
Published: October 2005

In VCV nonsense utterances while both the C-to-V transition and the V-to-C (implosive) transition are perceptible, the C-to-V transition has been found to be more important for stop consonant identification. Thus, the question arises; what role, if any, does the implosive transition play in word perception? Stimuli were two-syllable English words in which the initial element was consonantal, followed by a tense vowel, followed by a labial or alveolar stop or fricative, e.g., “gravy”. Each word was constructed in three ways: (1) the implosive transition was inappropriate in either place, manner or both; (2) the implosive transition was removed and the steady state of the vowel extended; and (3) original word. Suprasegmental variables were identical in all conditions. Data from a paired-comparison preference task and a word/nonword decision task indicate that while inappropriate implosive transitions hinder word identification, lack of implosive transitions does not. To determine whether appropriate implosive transitions facilitate word identification, we are using reaction time to make word/nonword judgments.
Consonant duration in speech production and perception of adults and children
Authors: Hawkins Sarah
Published: October 2005

A method of adjustment to internal criterion was used to investigate the perception of consonant duration. Three adults and two children, 5 and 7 years old, adjusted the durations of /s/ and /t/ in the synthesised words say, tay, stay, and stray. The words were presented in two synthesised sentences, in both an adult male and a child's voice. The perceptual data were compared with speech produced by the same and different subjects. The just noticeable difference (jnd) for consonant segment duration was of the order of 25 msec; but the internal criterion for “acceptable” durations can shift over time by more than the jnd at any one time. Durations of /s,t/ in perception and production were strongly associated within and between subjects, but there were some interesting adult—child differences. Compared with adults, children appeared to lack sensitivity to differences between sentence contexts in the same speaker voice, but to differentiate more between /s,t/ durations they required for the child versus the adult speaker.The differences required in perception for the child speaker did not always mirror the child listener's own production durations. These data are interpreted with respect to possible processes governing the regulation of segmental timing and rhythm in perception and production. [Supported by SRC, Great Britian.]
Perception of /w, r, l, y/ by normally articulating and misarticulating children
Authors: Bremer Christine D. , McGovern Katherine
Published: October 2005

Three ten-step series of synthetic speech stimuli were constructed: /ræm/ to /læm/, /ræm/ to /wæm/, /læm/ to /yæm/. Within each series, differences consisted of variations on onset frequency and slope of transition in F2 or F3. These stimuli were presented to 5- to 7-year-old children in identification (picture-pointing) and 3-step same—different (AX) discrimination tasks. Two groups of subjects were tested: children having normal articulation and children who misarticulated /r/ or /l/. Results support the view that some articulation-disordered children exhibit correlated perceptual deficits. [Research supported by NICHD grant No. HD-00098 to the Center for Research in Human Learning, NIMH grant No. MH-21153 to J.J. Jenkins and W. Strange, and NICHD Contract No. NO1-HD-1-2420 to Haskins Laboratories.]
Stimulus dominance in dichotic listening
Authors: Speaks Charles , Nicuum Nancy , Johnson Cynthia , Carney Edward
Published: October 2005

Twenty-four listeners received 20 dichotic-listening trials of natural stop-vowel syllables aligned by reference to onset of noise burst. Listeners marked two responses for each of the 30 pairs of syllables per trial, which provided 480 pairs of responses for each pair of syllables. The direction of ear advantage varied considerably across the 30 pairs; 11 had a significant REA, 10 had a significant LEA, and a nonsignificant ear advantage occurred for nine pairs. These differences in direction arose mainly from stimulus-dominance effects in which the advantage belonged to one member of a pair independent of which ear received the syllable. Stimulus dominance will be discussed from two perspectives. The first is feature dominance; voiceless stops, on the average, produced higher scores than voiced stops in voiced-voiceless pairs. The second is syllable dominance; performance was sufficiently low for two syllables, /ba/ and /da/, to account for a substantial amount of the observed stimulus dominance. These two alternatives will be interpreted with respect to binaural intelligibility of the syllables in the presence of masking noise. [Supported by PHS Grant No. NS-12125.]
Perceptual switching in bilinguals
Authors: Elman Jeffrey L. , Diehl Randy L. , Buchwald Susan E.
Published: October 2005

Three groups of subjects, monolingual English speakers, monolingual Spanish speakers, and English-Spanish bilinguals, identified a series of naturally-produced syllables which varied in voice-onset time (from /ba/ to /pa/). The two monolingual groups differed substantially in their identification performance with English speakers tending to label most of the syllables as /ba/ and Spanish speakers tending to label most of them as /pa/. The bilingual subjects heard the test stimuli in both an English and a Spanish context, each designed to induce a particular language “set”. These subjects perceived a reliably greater number of the test items as /ba/ in the English context than in the Spanish. The magnitude of this perceptual switching effect depends on the listener's degree of bilingualism.
Tone spreading, perception and linguistic background
Authors: Maddieson Ian
Published: October 2005

At the 92nd Meeting of the ASA, results of an experiment investigating perceptual asymmetries in tone-spreading environments were reported [J. Acoust. Soc. Am. 60, S45 (A) (1976)]. It was shown that in an ambiguous case a syllable was more likely to be judged to be high toned than low toned. In addition, the ambiguous syllable was more likely to be judged to have a tone which was the same as the tone of the following syllable rather than the preceding syllable. This result was unexpected, as, in tone languages, perseverative tone spreading is more frequent than anticipatory tone spreading. The subjects in this experiment were speakers of English, and the unexpected result could be due to the fact that English is not a tone language. In order to see if the linguistic background of subjects affected the results, the same experiment was conducted with speakers of Nigerian-tone languages. A comparison of the results from the two groups of subjects will be presented. [Work supported by NSF.]
Noncategorical perception of tone categories in Thai
Authors: Abramson Arthur S.
Published: October 2005

Arguments continue over categorical perception of phonetic segments versus continuous perception. In tone languages, phonemic tones are characterized principally by F0 contours. Theories of categoricity would predict continuous perception of tones; i.e., there out to be no peaks in the discrimination of variants at category boundaries, more as in experiments with isolated synthetic vowels than with synthetic stop consonants. This was the outcome of earlier work [A. S. Abramson, J. Acoust. Soc. Am. 33, 842 (1961)], but it seems to have been contradicted by recent work on Mandarin [S. W. Chan, C-K. Chuang and W. S-Y. Wang, J. Acoust. Soc. Am. 58, S119 (A) (1975)]. The present study involves a considerably larger number of subjects, 34 native speakers of Thai, a language with five phonemic tones. Sixteen flat F0 variants synthesized on a syllable of the type [kha:] were sorted into the three “static” high, mid and low tones with considerable overlap. Discrimination tests yielded a high level of discrimination across the continuum with no effects of boundaries between categories, thus implying noncategorical perception of tone categories.
Syllable affixes in speech snythesis
Authors: Macchi M. J. , Nigro G.
Published: October 2005

Fujimura has proposed that English syllables be treated as a syllable core plus syllable affixes [O. Fujimura, J. Acoust. Soc. Am. 59, S25 (A) (1976)]. Since the core may contain only one true postvocalic consonant, syllable-final consonant clusters are derived by attaching one or more affixes, the apical consonants /tdszθ/. According to this analysis, it should be possible, in a speech synthesis-by-rule system, to concatenate syllable affixes to the syllable core with only simple coarticulatory rules. We report on several experiments testing the feasibility of this approach. In one experiment, phonetic affix segments corresponding to /s/ and /z/ were sliced onto CVC syllable cores, in which the core-final consonant varied in terms of place and manner of articulation. The original and concatenated versions of each test syllable were presented to listeners who rated each version according to naturalness. In general, there was no difference in rated naturalness between the concatenated syllables and the originals, showing the feasibility of the process of affixation for /s/ and /z/. A similar experiment is being conducted for /t/ and /d/ affixes.
Memory, comprehension, and judged quality of synthetic speech under several prosodic conditions
Authors: McHugh A. , Larkey L. S.
Published: October 2005

Prosodic information contributes to the understanding of natural speech. Stress and timing convey semantic and syntactic information. Similarly, acceptable synthetic speech depends on more than correct phonemic specification. Appropriate intonation and timing patterns should improve the speech quality. Not only should such speech be judged to sound better, but one might also expect improvement on a number of other tasks such as memory, comprehension, or listening under adverse conditions (e. g., noise). Tests were conducted using multiple versions of synthesized sentences, paragraphs, and word lists. All had the same phonemic sequence but varied in prosodic specification. Possible versions were as follows: no stress information (a monotone), inflection information alone (pitch/loudness changes), timing information alone, or both inflection and timing. Listener ratings were very consistent: the more correct prosodic information was available, the better the speech was judged to sound. Scores on a simple comprehension test were higher for “good” versions only with unpracticed listeners. There was some evidence that with a more stringent memory test, scores were higher for prosodically good versions. [Work supported by NINDS, NICHD, and NIMH.]
Mathematical framework for time-scale modification of speech signals
Authors: Portnoff M. R.
Published: October 2005

There are a variety of applications in which it is desired to modify a speech signal in such a way that its speed is changed while its intelligibility and natural quality is retained. An appropriate mathematical representation for the speech waveform is formulated such that time scaling the parameters of the representation corresponds to effecting the desired time-scale modification. A high-quality analysis/synthesis system based on this representation was designed and simulated. This system employs short-time Fourier analysis techniques to implement the desired modification of the speech signal and is capable of producing high-quality speed-transformed speech with large compression and expansion factors. Issues such as non-integer scale factors, phase unwrapping, and feature-dependent (nonuniform) modifications will be considered.
Interrelationship between several classes of narrowban digital speech communication techniques and an underlying canonical baseline system
Authors: Walter C. M.
Published: October 2005

Statistical redundancy minimization techniques are used to transform from a conventional time-based digital signal representation to its canonical coordinate representation. A similar canonical representation is shown to hold when redundancy minimization is applied to a frequency-based representation of the same signal data ensemble. The relationship of this underlying canonical baseline system to both LPC-type analysis/synthesis systems and to power spectrum type systems, such as channel vocoders, is illustrated. Meansquare error bounds are derived in terms of the eigenvalues of a short term cross correlation matrix and are used to estimate the relative performance of several different classes of speech data compression systems. These results are compared with the results of intelligibility score data that was obtained on the performance of both LPC and channel vocoder systems. Computationally simple methods for carrying out the redundancy minimization process, for cyclic stationary data, are described, as one mechanism for implementing the canonical baseline system.
Phonetic labeling by template matching
Authors: Goldberg Henry G. , Reddy Raj
Published: October 2005

Results are reported of recent investigations into improving the basic template match scheme often used for initial phonetic labeling of speech segments. The technique is sensitive to (1) The set of templates (What are relevant phonetic classes?), (2) The manner of template derivation (Average a set of samples? Which set? Best representative? Most common?), and (3) The a priori labeling of training samples. (What is “correct” in Phonetics?) A novel approach to problems 1 and 3 is taken by employing the Harpy speech recognition system [B. Lowerre, Ph.D. dissertation, Carnegie-Mellon University, 1975] to define the best fit of a phonological dictionary to the segmental pattern space signal. Treating the population of training patterns as a distribution of (possibly mislabled) samples offers some solutions to (1) and (2) above. Intra-population clustering, using sample distributions to reject mislabeled training samples, and correcting the template match score by training population statistics are techniques which were investigated. Improved methods for template derivation, sample rejection, and match score correction yield significant improvements in labeling accuracy and overall speech understanding system performance.
Influence of hearing aid nonlinear distortion on closed set intelligibility performance in noise
Authors: Schweitzer H. C. , Howard M. T.
Published: October 2005

Two hearing aids of highly similar electroacoustic characteristics except for notable differences in nonlinear distortion were used in a study of speech intelligibility. Bandpass filtering provided further assurance of electroacoustic homogeneity. New recordings of Modified Rhyme Tests (MRTs) were recorded through these hearing aids in the presence of speech spectrum noise. Signal-to-noise ratio at the input to the hearing aids was +3 dB. Thirty normal-hearing young adult listeners gave written responses on the six-foil closed-set intelligibility test. Despite substantial differences between the aids for both harmonic and intermodulation distortion, no differences on intelligibility were obtained. Mean performance was 2% better for the aid with the higher distortion but the t score was non-significant. [Work supported by VA.]
Mouth/voise synthesis for lipreading research
Authors: Erber Norman P. , De Filippo Carol Lee
Published: October 2005

Relative onset times of voicing and visible articulation are potential cues for lipreaders to recognize nasal/stop consonants. For bilabials, a phototransistor behind the teeth and an external microphone indicated mouth opening and voice onset, respectively. Average voice leads for ten adults were: /ma/, +66 msec; /ba/, −1 msec; /pa/, −8 msec (/ma-ba/ boundary, +28 msec; /ba-pa/ boundary, −18 msec). To test relative voice/mouth onset as a perceptual cue. we produced synthetic syllables: the face substitute was an oscilloscope pattern, forming a mouth shape for 250, 400. or 550 msec; the voice substitute was a vowel-like buzz delivered through a hand-held vibrator. Buzz accompanied mouth opening with lead times of +200 to −200 msec (40 msec steps), and ended simultaneously with mouth closure. Normal-hearing observers labeled each combination “ma” “ba.” or “pa.” Practiced lipreaders with knowledge of the onset cue subdivided the continuum with boundaries at +82 msec (ma-ba) and −87 msec (ba-pa). Because articulatory and perceptual boundaries are not coincident, this combined-mode cue appears insufficient unless performance can be improved through training.
Development of directional responses toward sound by young guinea pigs
Authors: Kelly Jack B. , Clements Maureen
Published: October 2005

Infant guinea pigs were tested in a circular apparatus for their tendencey to approach the source of auditory stimulation. A tape recording of guinea pig vocalizations was played over a loud speaker and the incidence of directional responses was noted. Even without external reinforcement there was a tendency to approach the particular stimulus used in this study within the first four days after birth. In order to determine the cues involved in infant localization, animals were tested with wax plugs inserted in one ear or in both ears. The plugs attenuated but did not totally eliminate sound entering the ear. Directional responding was reduced to chance by monaural blocking, but not by binaural blocking. Similar results were obtained with older animals eleven to thirty-one days of age. Furthermore, directional responding was impaired in animals raised from birth with monaural ear plugs, but tested without ear plugs. These results indicate that sound localization occurs early in development in the guinea pig, that binaural cues are important, and that monaural deprivation can affect subsequent responding.
An investigation of speaker height and weight identification: II. Direct estimations
Authors: Lass Norman J. , Beverly Amy S. , Nicosia Debra K. , Simpson Laurel A.
Published: October 2005

Results of a previous investigation [N.J. Lass and M. Davies, J. Acoust. Soc. Am. 60, 700–703 (1976)], in which subjects were given a multiple-choice response task for their judgments, indicated that listeners were capable of identifying the heights of male and female speakers and the weights of male speakers at better than chance levels. The purposes of the present investigation were: (1) to determine if listeners were also capable of making accurate direct estimations of speakers' heights and weights from recorded speech samples (without the benefit of available multiple choices), and (2) to determine the importance of the sex of the speaker and listener on speaker height and weight identification tasks. A standard prose passage was recorded by 30 speakers, 15 females and 15 males. A master tape containing the randomly arranged recorded readings of all speakers was played to a group of 40 judges, 20 females and 20 males. All subjects participated in two experimental sessions. In one session they were asked to determine the height of each speaker and in another session weight judgments were made. The order of presentation of the two experimental tasks was randomized so that 20 subjects made height judgments first and 20 made weight judgments first. Results indicate that listeners are capable of accurately identifying the approximate heights and weights of speakers by means of direct estimations. Moreover, the sex of the speaker and listener did not significantly affect speaker height and weight identification judgments. Implications of these findings and suggestions for future research are discussed.
Large speech data bases
Authors: Reddy D. Raj , Lowerre Bruce T.
Published: October 2005

It is easy enough to digitize a large amount of speech data. But before it can be effectively used in speech research, it must be cataloged to indicate position and descriptions of words and phones that are present in the data. In the absence of adequate tools, experts must do these tasks manually. Given interactive, automatic, and semiautomatic speech analysis programs, one can significantly improve the quality of the data base and the productivity of the experts. This paper describes the structure and characteristics of programs developed at Carnegie-Mellon University which interactively bootstrap themselves to generate symbolic descriptions of a given set of data. The present system contains programs for (1) generating environment and speaker adapted phone templates (2) interactive generation of a phone lexicon containing alternating pronunciation of words generated from data, and (3) a program for machine aided labeling of a given phrase or sentence giving the beginning and ending of each phone and each word. Using these programs, over three hours of connected speech data has been digitized, and analyzed, to generate symbolic descriptions of the data in terms of phones and words. Retrieval programs are then used to retrieve all symbols satisfying a given property.
Ultrasonic velocity and absorption measurements in several binary mixtures with pyridine
Authors: Gupta P. K. , Stumpf F. B.
Published: October 2005

Ultrasonic velocity and absorption measurements have been made with binary liquid mixtures of pyridine with heavy water, phenol, and tertbutyl alcohol. These measurements were conducted with pulsed ultrasound at a frequency of 19.5 MHz. The data was taken at several temperatures between 15° and 40°C. By taking measurements at several concentrations of each liquid mixture, information about the molecular association between the two different molecules in the liquid mixture was obtained. Previous work has been done with binary mixtures of pyridine with water, methanol, and ethanol [K. N. Thomas and F. B. Stumpf, J. Acoust. Soc. Am. 53, 714–718 (1973)].
Diffraction-based tissue characterization with ultrasound
Authors: Lee Paul P. K. , Lerner Robert M.
Published: October 2005

Although ultrasound has been used in medical imaging because of its nonionizing nature and ability to depict soft tissue structures, it also promises to provide noninvasive means of tissue characterization by signal amplitude quantitation, frequency dependent absorption measurement, and application of diffraction concepts. Diffraction-based methods provide ways of determining scatterer distribution within a sample volume on a scale corresponding to the wavelength. The underlying concept is wave interference resulting in selective reinforcement or cancellation of signals depending on wavelength, scatterer spacing, and geometry as in Bragg diffraction. By sweeping frequency or varying scattering angle, data analogous to x-ray diffraction is obtained for inference of scatterer size, or spacing from Fourier analysis. Scattered ultrasound intensity from regular arrays of cylinders has been measured as a function of frequency. Data reduction yields spacings that correspond well with actual values. Measurements of scattering as a function of angle from small particles have produced results which are in qualitative agreement with theoretical predictions. Preliminary in-vitro studies of scattering from human liver indicate the importance of off-axis scattering for tissue characterization. The studies show the promise of the approach but indicate that more work is required to develop diffraction concepts for ultrasonic characterization of tissue.
Investigation of the stability of separated shear layers in a thin (6 mm) two dimensional jet of air using a new computer-assisted synchronous hot wire technique
Authors: Schubert D. M.
Published: October 2005

An instability which causes initially laminar flow to develop an exponentially growing fluctuation was initiated artifically with sound from a loudspeaker. There were two types of fluctuations observed: symmetric, where the jet's two shear layers fluctuate in phase, and antisymmetric, where the fluctuations are 180° out of phase. Longitudinal velocity profiles have been plotted using the CASH technique (Elder, see paper M5), which separates the periodic component of velocity fluctuations from background turbulence using computer averaging. Analysis of the data will attempt a complete two-dimensional mapping of the velocity fluctuations, using the phase of the driving wave as a reference. A study will be made of the breakdown of the exponential growth as the transition to turbulence takes place. An attempt will be made also to study the development and the trajectories of eddies, and determination of the complex phase velocity of the instability waves. Results will be compared with earlier papers on the subject, particularly the classic work of Sato [H. Sato, J. Fluid Mech. 7, 53–80 (1960)].
Recent approaches to transducer array beamforming
Authors: Maksym J. N. , McMahon G. W.
Published: October 2005

The development of underwater acoustic array-processing and beamforming methods over the past decade is reviewed briefly. The trend in this period is away from fixed designs typified by shaded-aperture time-delay beamforming toward stored-coefficient and adaptive systems made possible in part by advances in digital hardware. Linear programming techniques have been used to generate prescribed directional response for arrays with fixed geometry, while nonlinear programming has allowed the inclusion of specified power response and element position as variables in the optimization process. More recently the emphasis has shifted to adaptively optimized systems, where the beam pattern adjusts to changing noise and interference fields. An example is given in which the beam pattern of an active Doppler-processing sonar is adapted to the directional properties of the reverberation noise field. Limitations imposed by nonideal transducer response on the optimization are illustrated through the use of coherent calibration data obtained with the transducer array.
Waveform coding in the inferior colliculus of the cat: cross-correlation of single unit responses with pseudorandom Gaussian white noise
Authors: Hosford H. L. , Sutter E. , Dawson B.
Published: October 2005

The linear filter characteristics (impulse response) of 96 afferent neurons have been determined by the process of cross-correlating neuron spike discharges with Gaussian white noise input. The results, representing the linear kernel of the Wiener—Volterra functional expansion for nonlinear systems, take the form of spike response-locked signal averages. Spike patterns of single units in three chronic awake cats were recorded during binaural stimulation with uncorrelated white noise presented through equalized insert ear phones. Penetrations of the inferior colliculus were confirmed histologically. Cross-correlation analysis of approximately 10 000 spikes was performed for each ear for each unit. Strong waveform periodicities in the contralateral linear kernels were found in a large majority of the cell population, while a smaller percentage also showed periodicities in the ipsilateral kernel, but of a different frequency. Linear kernels also provide quantitative information about unit latencies, phase locking, and “memory.” Good agreement is found between frequency coding revealed by noise stimulation and frequency response histograms which we obtained from conventional harmonic analysis.
Comparison of acoustic reflex thresholds using conventional and tracking measurement methods
Authors: Cohill E. N. , Greenberg H. J.
Published: October 2005

Use of an experimenter-controlled tracking procedure to obtain acoustic reflex thresholds has recently become popular. In this method, the intensity of the stimulus is adjusted by the experimenter to bracket the acoustic reflex threshold as visually observed on the meter of an acoustic impedance measuring device. The midpoint of the tracings is taken as the reflex threshold. Conventionally, the acoustic reflex threshold has been defined as the intensity needed for minimum meter deflection. This study investigated the relationships between acoustic reflex thresholds obtained using the two procedures. Acoustic reflex thresholds were obtained to pure tones of 500, 1000, 2000, and 4000 Hz. An ascending approach using manually interrupted tones in 5-dB steps was employed to determine the conventional reflex thresholds. A self-recording audiometer with a 2.5/sec pulse rate and a 5-dB/sec attenuation rate was used to obtain the tracking reflex thresholds. High correlations and no significant differences were found between the acoustic reflex thresholds obtained using both methods indicating similar accuracy in their measurement of threshold. It was concluded that the tracking method which allows easier control of stimulus parameters and response recording can provide acoustic reflex threshold data similar to those obtained using a conventional method.
Localization of brief sounds by pigeons
Authors: Jenkins W. , Masterton R. B.
Published: October 2005

The ability of pigeons (Columbia livia) to localize brief sounds was assessed using a two-choice procedure. The pigeons first pecked a lighted key located at the center of a 76 cm. semicircle triggering a sound from one of two speakers separated by 120° at the periphery. If they then walked to the sound source and pecked a lighted key above it, they were rewarded with momentary access to grain. Although at first they were reluctant to approach the active speaker, eventually they demonstrated their ability to localize either a brief white noise burst or a tone pip. However, their ability to localize a tone pip varied markedly with frequency. A symptotic performance levels were found to be above 90% at 125 Hz and 250 Hz, 73% at 500 Hz, 59% at 1 kHz, 60% at 2 kHz, 67% at 4 kHz, and above 90% again at 8 kHz. Therefore, pigeons can lozalize low and high frequencies well, but middle frequencies (1K and 2K) only with difficulty. Localization in this midrange of frequencies is greatly and immediately enhanced when a narrow band of white noise is substituted for the tone pip.
Auditory effects of long exposures to noise. I. Temporary threshold shifts in human observers exposed to octave-bands of noise for 18–26 h
Authors: Mills J. H. , Gilbert R. M. , Adkins W. Y.
Published: October 2005

Human subjects were exposed in a diffuse sound field for 18–26 h to an octave-band noise (center frequency 4.0, 2.0, 1.0, or 0.5 kHz) of fixed SPL. Except for the band centered at 0.5 kHz, sound levels were varied on different exposure occasions. During an exposure subjects were removed from the noise, auditory sensitivity was measured, and the subject was returned to the noise. Threshold shifts increased for the first 4–12 h of exposure and then reached a plateau or asymptote. The relation between the threshold shift at asymptote (ATS), in the frequency region of greatest loss, and the level of the noise is given by the equation ATS=1.7[10 log10 (Ie + Ic)Ic] where Ie is the sound pressure of the noise, and Ic is the sound pressure of a constant C which is a critical level and is dependent upon the center frequency of the noise. The empirically determined value of C for humans are 82 dB SPL at 0.5 and 1.0 kHz, 78 dB at 2.0 kHz, and 74 dB SPL at 4.0 kHz. The equation describes accurately human data from four labs, chinchilla data from two labs, and monkey data from one lab. It is quite possible, therefore, that this equation describes a general property of many mammalian ears with, of course, appropriate corrections for the critical level, C. [Supported by NIEHS.]
Ear canal resonance and temporary threshold shift
Authors: Caiazzo Anthony J. , Tonndorf Juergen
Published: October 2005

An investigation was made to determine if a relation exists between ear canal resonance and the characteristic 4-kHz notch of noise-induced hearing loss. In normal-hearing subjects (N = 15), temporary threshold shifts (TTS) were induced in a free-field situation under two different conditions: (1) with the ear canal in its normal configuration and (2) with the canal extended to approximately twice its normal length and terminated by an artificial pinna. Under condition (1) the typical 4-kHz notch was observed. Under condition (2), the notch occurred at approximately 2 kHz, i.e., at one-half the normal frequency. Although for equal exposure (in terms of sensation level) no difference in TTS magnitude was observed between the two conditions, subjects demonstrated consistently longer recovery times, i.e., shallower dB/log time slopes, with the canals extended. Results support the notion that the noise-induced 4-kHz notch is mainly related to the ear canal resonance. [Supported by NIH grants.]
Underwater acoustical astrophysics: Project DUMAND
Authors: Parvulescu Antares
Published: October 2005

Project DUMAND (Deep Underwater Muon and Neutrino Detection) is an informal organization seeking to use the ocean depths as a shield to unwanted cosmic rays while using the water itself as a particular detector for neutrinos and the rarer kinds of muons. Recent work suggests that acoustical detection of the hadronic cascade produced by interaction with water would be the preferred process. Two distinctly different theories have been proposed; the corresponding estimates for the sound pressures caused by ultra-high-energy [1016 eV] neutrinos differ by 146 dB. Experiments with proton showers at Brookhaven indicate that the conversion of particle energy to sound almost agrees with the more pessimistic theory, being some 15–20 dB higher. Even this low conversion efficiency might permit detection of neutrinos and muons generated by astrophysical catastrophes, e.g., gravitational collapse, colliding galaxies and the remordial Bang. The acoustical unknowns confronting a potential experimental facility are: the proper theoretical model; the statistics of ambient noise whose waveform mimics the particle event; process of 104–105 hydrophone signals (up to 100 kHz) in a cubic mile of ocean so that source location and shape may be determined; data transmission to shore; and possible engineering configurations. Experiments now underway and being planned will be outlined.