bluuebunny/crossref_metadata_2025 huggingface dataset:
Topographic organization in the brainstem auditory system: Projections of specific neuronal types
Authors: Cant Nell Beatty
Published: October 2005

Connections in the auditory system will be discussed from the point of view of the efferent projections of specific cell types of the cochlear nucleus and the topography of their terminations in the superior olivary complex and the inferior colliculus. Three cell types will serve as examples: spherical bushy cells and multipolar cells of the ventral cochlear nucleus and fusiform cells of the dorsal cochlear nucleus. The spherical bushy cells project to both the lateral and the medial superior olivary nuclei. Both projections are organized topographically with respect to the cochlear receptor surface. The convergence and divergence of the inputs from the bushy cells will be emphasized. The multipolar cells of the ventral cochlear nucleus and the fusiform cells of the dorsal cochlear nucleus project to the inferior colliculus. Both projections appear to be topographically organized, but the projection patterns within the inferior colliculus may be somewhat different. When the topography of the projections with respect to the cochlear receptor surface is established, other aspects of the spatial organization can be considered. Small strips of the cochlea are represented in the auditory pathways in “sheets” or “bands” of neuronal tissue. Stacks of these sheets or bands form the basis for the well-known tonotopic organization in areas from the cochlear nucleus to the auditory cortex. In the auditory cortex, another level of organization within isofrequency representations has been demonstrated. Evidence for an analogous organization within isofrequency representations in other parts of the auditory system, including the cochlear nucleus, will be presented. Where possible, this organization will be related to the organization of the projections of identified cell types.
Energy detection in the ocean acoustic environment
Authors: Machell Fred W. , Penrod Clark S.
Published: October 2005

The performance of the energy detector is evaluated using ambient noise data from several ocean acoustic environments. Estimates of the false alarm probability are presented as a function of the detection threshold for each environment. Estimated values for the corresponding minimum detectable signal-to-noise ratio (MDS) are also given for an artificially generated white Gaussian signal. The results presented indicate that nonstationary and non-Gaussian noise statistics can have a significant impact on the relationship between the false alarm probability and the detection threshold. This threshold adjustment results in a serious degradation of energy detector performance in terms of the MDS for some non-Gaussian noise environments. [Work supported by the Office of Naval Research.]
Randomized arrays
Authors: Lockwood James C.
Published: October 2005

In previous treatments of random arrays [see, for example Thorn, Booth, and Lockwood, J. Acoust. Soc. Am. 67, 1277 (1980)] the probability density functioin (pdf) of each element position has generally been assumed to extend over the entire array dimension. In such cases the ensemble average pattern amplitude is generally small outside the main lobe and the pattern amplitude variance depends on the number of independent element positions. The present work begins with an array that is not random and examines the behavior of the ensemble average and variance of pattern amplitude as the element coordinates are randomized within specified regions about the original positions. The size of the regions is a parameter that can extend from zero up to the full array size. it will be shown that the pattern amplitude average and variance depend on both the design pattern of the original element positions and on the size of the region within which the coordinates are randomized. If this region is significantly less than one acoustic wavelength, it will be seen that the pattern statistics differ substantially from those of a totally random array. [Work supported by Naval Material Command.]
Exercise in acoustic measurement and signal analysis: A real-world approach
Authors: Hixson Elmer L.
Published: October 2005

This presentation emphasizes measurement and analysis exercises appropriate for an introductory course in acoustics and/or noise control, or for a course in acoustic measurements. The exercises are chosen to represent the blending of measurement and interpretation required by acousticians without elaborate laboratories. The critical question is “How do we obtain useful information in spite of a hostile (less than ideal) environment?” One set of demonstrations illustrates complementary frequency and time domain analysis techniques for in-situ measurements. The areas of application, advantages, and pitfalls of each technique are discussed. Another suggested exercise involves the relationship between sound-field surveys and their environmental implications.
The evolution of real-time music synthesizers
Authors: Mathews M. V.
Published: October 2005

A broad history of real-time synthesizers will be traced. One root goes back to electronic tape studios pioneered in the early 1950's by Ussachevsky and Luening in the United States and by Schaeffer and Stockhausen in Europe. The RCA synthesizer (Olson, Belar), modular synthesizers (Moog), keyboard-controlled synthesizers, and sequencer-controlled synthesizers were notable developments along this path. Another root goes back to pure digital synthesis in the late 1950's (Mathews, Chowning). Developments include the computer-controlled analog synthesizer (Mathews, Moore) and the digital synthesizer (Alonzo, Appleton). Today realtime synthesizers can be purchased at prices ranging from less than $100 for toys to more than $100,000. In the future we expect close association of synthesizers and personal computers plus special VLSI music chips which will greatly reduce costs and strengthen the power of the synthesizers.
Real-time synthesis using the Synclavier
Authors: Mendelsohn Brian
Published: October 2005

The operating principles of the Synclavier are discussed. Demonstrations are performed on an actual instrument.
Interior dynamics of acoustic scattering from elastic cylindrical targets
Authors: Raju P. K. , Subrahmanyam J. V. , Überall H. , Nagl A. , Flax L.
Published: October 2005

The interior fields in a glass cylinder, immersed in water and subject to an incident acoustic plane wave, are studied via an application of the resonance theory of acoustic scattering. They consist of resonant amplitudes only, and substantial penetration of the incident field into the scatterer occurs only at or near resonance frequencies. The dynamics of the interior motions is investigated here; the results are compared to, and agree with, experimentally measured fields inside glass cylinders by the method of optic-elastic birefringence. The elastic body is shown to undergo resonances in the radial and angular directions, except for the case of the breathing mode. [Supported by the Office of Naval Research.]
Dynamic properties of elastomers containing a random distribution of nonspherical inclusions
Authors: Varadan V. K. , Varadan V. V. , Ma Y. , Madigosky W. M. , Scharnhorst K. P.
Published: October 2005

A self-consistent multiple scattering theory will be employed to study the frequency-dependent complex material properties of elastomers containing a random distribution of nonspherical inclusions. It has been found that “superviscous” damping can be achieved by exciting resonances of the inclusions by a judicious choice of matrix and filler properties, filler size, geometry, and frequency of the wave. Numerical results will be presented for various shapes, material properties and orientations of the inclusions and compared with some available experimental results.
Categorical tendencies in vowel imitation: I. Synthetic vowel stimuli
Authors: Williams David R. , Repp Bruno H.
Published: October 2005

The question whether isolated stationary vowels are imitated in a continuous or categorical fashion [R. D. Kent, Phonetica 28, 1–25 (1973)] was pursued further by replicating Kent's study with slight modifications. The subjects (the two authors) imitated synthetic stimuli from [u] - [i] and [i] - [æ] continua at three different temporal delays. Acoustic analysis of the response vowels revealed very similar patterns across delays. Both subjects showed clear evidence of nonlinearities in the stimulus-response mapping and of preferred response formant frequencies, though strictly categorical responses were generally absent. The origin of these nonlinearities and their relation to the phonemic vowel categories of English are not fully understood at present. Vowel imitation responses presumably reflect the joint influences of perceptual and articulatory factors that need to be disentangled in future research. [Work supported by NICHD Grant HD-01994.]
Principal component amplitude compression of speech for the sensorineural hearing impaired
Authors: Bustamante D. K. , Braida L. D.
Published: October 2005

This study investigated the ability of principal component (PC) amplitude compression [D. K. Bustamante and L. D. Braida, J. Acoust. Soc. Am. Suppl. 1 74, S104 (1984)] to compensate for reduced dynamic range in sensorineural hearing impairments. Two types of PC compression were examined: compression of the lowest-order PC (corresponding roughly to overall level), and compression of the two lowest-order components (corresponding to both overall level and slope). For comparison purposes, wideband compression, independent multiband compression, and linear amplification were also tested. Subjects with moderately severe and severe sensorineural hearing losses identified CVC nonsense syllables spoken by one male and one female speaker. Training was performed at each subject's MCL, and testing was conducted at two input levels, MCL and MCL-10 dB. A detailed discussion of the results will be presented. [Work supported by NIH.]
Representation of synthetic vowels in the cochlear nerve sad cochlear nucleus of the guinea pig
Authors: Palmer A. R. , Winter I. M. , Darwin C. J.
Published: October 2005

Responses were measured in anaesthetized guinea pigs of cochlear nerve and nucleus neurones to synthetic /i/, /a/, and /u/ vowels at 60 and 80 dB SPL. Fourier transformation of period histograms locked to the pitch period (100 Hz) generated from the response during the last 38 of 40 vowel periods presented at 1/s was used to measure the response to the harmonics of the vowel. The response of the nerve fiber population assessed by either average localized synchronized rate or by the dominant response component [e.g., E. D. Young and M. B. Sachs, J. Acoust. Soc. Am. 66, 1381–1403 (1979)], was very like that reported for the cat. The first three formants and F0 were well represented in the nerve rate/time/place code up to 80 dB SPL. Similar analyses of ventral cochlear nucleus primary-like neurones revealed that, at least in this preparation, the rate/time/place code is not faithfully transmitted through this first synaptic relay. In this primary-like population the peaks of discharge synchronized to the formants are less distinct and may be absent. [Work supported by the Royal Society and MRC.]
Cochlear prostheses: Stochastic model of electrical excitation
Authors: White M.
Published: October 2005

In a model of intracochlear electrical stimulation, an integrated Gaussian function defines the probability of auditory-nerve-fiber discharge versus stimulus amplitude. The stimulus current delivered to each fiber is a function of the distance between the stimulating electrode and excitation site. In the model, behavioral threshold is reached when a fixed number of discharges are elicited from converging fibers over a time interval of 100 ms. Model simulations indicate that stochastic behavior in peripheral auditory nerve processes strongly affects behavioral thresholds. The relative level of neural membrane noise was estimated by comparing model predictions with measurements of behavioral threshold as a function of the number of stimulus pulses. Estimated membrane noise levels are similar to those observed in unit recordings in electrically stimulated cochleas. Estimated membrane noise levels are relatively high, as might be expected with stimulation of small-diameter dendrites. Estimated levels of stochastic activity may be related to the status of dendrites in the cochlea.
Formant discrimination in a multichannel cochlear prosthesis
Authors: White M. , Ochs M. , Raggio M. , Morledge D. , Merzenich M.
Published: October 2005

The ability of an implanted subject to utilize second formant frequency (F2) information was investigated. The speech signal was split into four bands: 200–800 Hz, 800–1450 Hz, 1450–2200 Hz, and 2200–8000 Hz. Each filter output was connected to a separate electrode. The subject listened to one stimulus and selected which of two vowels sounded more like the stimulus. One vowel had a high F2 and the other had a low F2 otherwise they were similar. Stimuli were 11 synthetic steady-state vowels, identical except in F2. F2 ranged from 1100–2100 Hz in 100-Hz steps. If the lower frequency bandpass filters were connected to the more apical electrodes, stimuli with low F2s sounded more like the low F2 vowel. The high F2 stimuli sounded like the high F2 vowel. When the electrode connections to the two filters passing F2 (i.e., the 800 to 1450 and 1450 to 2200-Hz filters) were reversed, a stimulus with a low (high) F2 sounded more like the vowel with the high (low) F2. In other words, when the filter passing low F2s was connected to a more basal electrode than the electrode connected to the filter passing high F2s, the categorizations were reversed. This study supports the value of differential stimulation of multiple electrode channels. [Work supported by NIH.]
Perceptual similarity of complex signals presented by electrical stimulation of the auditory nerve
Authors: Widin Gregory P. , Soli Sigfrid D. , Kirby Virginia M.
Published: October 2005

Electrical stimulation of the auditory nerve bypasses the transduction mechanisms of the cochlea. Thus the properties of electrical stimuli that make them perceptually similar or dissimilar may differ from those of acoustical stimuli. We have examined the influence of bandwidth, center frequency, peak factor, spectral shape, and tonality on perceptual similarity. Nineteen stimuli were presented electrically to four cochlear implant subjects and acoustically to two normal-hearing subjects. All subjects first adjusted the stimuli for equal loudness and then rated their similarity in a triadic comparison task. The similarity matrices from the triadic mask were submitted to multidimensional scaling analyses using the KYST-2A and SINDSCAL programs. The obtained stimulus configurations and dimensions for implanted and normal-hearing subjects will be discussed and interpreted in terms of the psychophysics of hearing with electrical and acoustical stimulation.
Identification of intonation contours by normal hearing and profoundly hearing-impaired listeners
Authors: Grant Ken W.
Published: October 2005

Poor control of voice pitch is a common attribute of the speech of profoundly hearing-impaired individuals that may be at least partially corrected through the use of visual or tactile pitch displays. Of concern in this study is why conventional hearing aids fail to provide the same degree of sensory feedback necessary for pitch control. To better understand why hearing aids fail in this regard, we measured the ability of normally hearing and profoundly hearing-impaired listeners to categorize synthetic intonation contours according to the location of the primary stressed peak in the contour. Listeners with a profound heating loss required approximately four times the amount of pitch inflection to locate the stressed position in the contour than did listeners with normal hearing. Implications for signal-processing hearing aids will be discussed. [Work supported by NIH.]
A test of predicted maximum susceptibility to impulse noise
Authors: Price G. Richard , Wansack Samuel
Published: October 2005

Given the hypothesis of a spectrally dependent critical level in the ear [G. R. Price, J. Acoust. Soc. Am. 69, 171–177 (1981)], it was predicted that for a cat ear, a Friedlander impulse with its spectral peak at 4.0 kHz would be maximally hazardous. To test this contention, both ears of 28 lightly anesthetized cats were exposed in an anechoic chamber to 50 impulses at 140-, 144-, or 150-dB peak SPL. Losses were measured electro-physiologically from the vertex at 2.0, 4.0, 8.0, and 16.0 kHz, 30-min postexposure and again 60 + days later. The data supported the hypothesis, with permanent losses being produced at pressures above 140 dB. A calculation revealed that the energy required to produce a 25 + dB PTS was only 0.4 J/m2. This energy is equivalent to an exposure for 8 h to only 72 dB SPL, which would not be expected to produce any permanent changes, even if repeated on many occasions. The data are interpreted as supporting the idea that a critical mechanical stress had been exceeded. Implications for damage-risk assessment will be discussed.
Temporary threshold shifts of hearing and physiological responses in men under complex exposures
Authors: Manninen Olavi J.
Published: October 2005

This study deals with changes in the temporary hearing threshold (TTS2), heart rate (HR), R-wave amplitude (RWA), diastolic blood pressure (DBP), systolic blood pressure (SBP) and pulse pressure (PP) in subjects (n = 108) who, while working, were exposed in an exposure chamber to combinations of broadband noise and whole body vibrations at dry bulb temperatures of 20° and 30 °C. The variance analysis model explained best the variation in TTS2 values at 4 kHz and second best the variation in TTS2 values at 6 kHz; it explained the variation in HR values third best, the variation in SBP values fourth best and the variation in PP values fifth best. On the other hand, the model explained least well the variation in DBP and RWA values. In general, the explanatory power of the model increased together with the number of exposures. The psychic stress of the competition type work accelerated the growth of the TTS2 values, HR values, and SBP values, when the subjects were simultaneously exposed to noise or to combination of noise and vibration. An interesting finding was that sinusoidal and stochastic vibration affected the cardiovascular changes and temporary hearing thresholds in different ways. [Work supported by the Academy of Finland.]
The growth of TTS as a function of the peak level and the duration of exposure to an impact noise
Authors: Hétu Raymond , Poirier Sylvie
Published: October 2005

The influence of the peak level and the duration of exposure on the growth of TTS was measured using an impact noise having a decay time of approximately 500 ms. Four normal hearing subjects participated in the experiment. For each subject, TTS was measured 2 min after exposure at the most affected ear and audiometric frequency for this particular noise. The subjects were exposed to series of impacts at peak levels of 102, 108, 114, and 120 dBA. The repetititon rate of 1 pps was kept constant throughout the experiment. Exposure durations of 0.5, 1, 2, 4, 8, 16, 32, and 60 min were tested. For the higher peak levels, the exposure was limited to durations that induced amounts of TTS inferior to 20 dB. Individual and median data relating TTS to exposure duration were fitted with a high degree of accuracy using Gumpertz functions. The median rate of growth of TTS doubled for each 6-dB increase in the peak level between 102 and 114 dBA. Asymptotic threshold shift appeared to be reached or approached within 60 min at 102 dBA, within 32 min at 108 dBA and within 16 min at 114 dBA.
Changing relationship between lovebird mates brought out through bioacoustics
Authors: Wheeler Leslie A.
Published: October 2005

Lovebirds are considered to be monogamous and to mate for life. Indeed, the particularly strong bond between Peak-faced lovebird mates (Agapornis roseicollis), and its importance to social organization, led us to believe that acoustic recognition could be demonstrated simply and unequivocally, and the acoustic signature on which it was based studied in a straightforward manner, using a classical two-choice mate-versus-other situation, in which the mate's calls (acoustically modified or unmodified controls) would invariably, or at least usually, be chosen. Processing of control data obtained over a 1-yr period with the same individuals indicates that this is not the case. A source of large variation in responses to unmodified calls is correlated with changes in pairbond strength and preferences for individuals other than the mate. Responses vary from changes in selectivity according to the identity of the second bird in the choice experiment to “negative recognition,” i.e., outright rejection of the mate. The good news is that the field of acoustics continues to astound and amaze with its versatility and usefulness in a wide variety of domains.
Segmental speech errors occur earlier in utterance planning than certain phonetic processes
Authors: Shattuck-Hufnagel Stefanie
Published: October 2005

If single-segment speech errors occur when planning segments are represented abstractly (i.e., independent of their immediate context), and contextual adjustments are made by later processes which apply after serial ordering errors have occurred, then these contextual adjustments should reflect the influence of segments which have been introduced by error. An example of such a contextual adjustment is the duration difference in CVC syllables, where the voiced portion of the syllable is longer if the final C is voiced, and shorter if the final C is voiceless. In an error-elicitation experiment using tongue twisters, ten instances were observed where final consonants exchanged, e.g., “dig duck”→“dick dug,” “pack pig”→“pag pick” etc. When these 20 syllables were compared with correct control utterances produced by the same speakers, 19 showed durations of voicing appropriate to the segment that was introduced by error, and one was equivocal. These results are compatible with the hypothesis that segmental interaction errors occur earlier in production planning than at least some phonetic processes, and that these processes then apply to error segments and correct target segments alike. [This research is supported in part by a grant from the National Institutes of Health.]
Individual differences and word-final devoicing in Polish
Authors: Slowiaczek Louisa M. , Dinnsen Daniel A.
Published: October 2005

Within phonological theory a fundamental distinction is made between rules that are neutralizing and those that are non-neutralizing. Recently, experimental research has examined a number of neutralizations and has found that they are, in fact, non-neutralizing, thereby raising questions about the validity of such a distinction (Dinnsen, 1984). The purpose of this paper is to report the results of an experimental study which investigated the phonetic implementation of word-final devoicing in Polish. All previous phonological accounts of Polish have characterized this devoicing rule as neutralizing. Fifteen pairs of words (distinguished underlyingly by word-final voicing) were recorded in two contexts (---- ♯C and ---- ♯V by five native speakers of Polish. Measurements of final consonant closure duration, voicing into closure, and preceding vowel duration were obtained for each subject. The results of this study showed that the underlying voice distinction is phonetically preserved. Moreover, we found variation in the implementation of the voice contrast for individual subjects. These findings are similar to those observed for Catalan which also exhibits non-neutralized word-final devoicing. [Supported by a research grant from NIH to Indiana University.]
Measures of phonation contrasts in Hmong
Authors: Huffman Marie K.
Published: October 2005

Previous studies of contrastive phonation types have found that measures of the prominence of the first harmonic relative to the first formant or lower harmonics are fairly reliable correlates of phonation contrasts involving normal, breathy, and creaky voice qualitites. Because variations in phonation type are attributed to the glottal source, it is of interest to determine the extent to which such spectral differences hold of the glottal flow waveform, one indicator of laryngeal behavior. Inverse filtered flow data were analyzed for normal voiced, breathy voiced, and so-called creaky voiced vowels of Hmong, a tone language of Southeast Asia. Spectral analysis indicated that the difference in relative amplitude of the fundamental frequency and the first harmonic (F0-H2) of the glottal spectrum is a very successful indicator of the normal versus breathy voice quality contrast. The supposedly creaky vowels did not differ by any spectral measure. [Work supportd by NINCDS.]
Distinguishing between tense and lax phonation in four minority languages of China
Authors: Ladefoged Peter , Maddieson Ian
Published: October 2005

The terms “tense” and “lax” have been applied to a number of different distinctions between vowel sets depending on the language(s) being discussed. Linguists working on Southeast Asian languages have used these terms to discuss phonological contrasts whose main component we can show to be one of phonation type. Aerodynamic and acoustic data were collected on four languages spoken in southwestern China—Jing-pho, Hani, Yi, and Wa. Vowel quality and duration and some properties of adjacent consonants were involved in the distinction in some of these languages, but not in a consistent way. However, oral airflow is greater for the “lax” vowels, particularly when considered in relation to the subglottal pressure (inferred from measurements of the oral pressure in voiceless bilabial stops preceding the vowel). Also the fundamental has greater amplitude relative to the second harmonic in “lax” vowels than in “tense” vowels. The agreement between these two measures confirms that the contrast is one of phonation type. [Work supported by NINCDS.]
Acoustic characteristics of fricatives and fricative-like models
Authors: Shadle Christine H.
Published: October 2005

Spectra of spoken fricatives and of the output of mechanical models designed to mimic fricatives were compared in order to test the applicability of such models to speech, and to explore the acoustic mechanisms of fricative production. Power spectra were computed from recordings of five speakers uttering the sustained fricatives [φ, f, θ, s, š, x]. Mechanical models were assembled using a variety of articulatory and aerodynamic data, guided by previous work with models [C. Shadle, J. Acoust. Soc. Am. Suppl. 1 75, S24 (1984)]. The models fell into three groups according to source location and type. To produce [s, š] an obstacle is required at the approximate location of the teeth. A very short front cavity is required for [φ, f, θ]; the jet of air must be located near the tube wall or other surface to mimic the role of the lips. For [x, ç] the palate and possibly alveolar ridge act as a turbulence-generating surface anterior to the constriction. Although perfect spectral matches are not attained in all cases, the mechanical models can be used to test the adequacy of source-filter representations of the fricatives. [Work supported by NINCDS.]
Measures of spectral tilt
Authors: Jackson Michel , Ladefoged Peter , Huffman Marie , Antoñanzas-Barroso Norma
Published: October 2005

Crude measures of spectral tilt (F0-H2 difference, and F0-F1 difference) have been demonstrated to be useful for distinguishing phonation types. However with such methods, it is difficult to control for differences due to variations in vowel quality and F0. In order to place such measures on a firmer foundation, the differences in vowel quality can be compensated for by inverse filtering. This technique has been used for analyzing vowels in languages having contrasting phonation types. FM recordings of airflow data in Burmese and Hmong, and ordinary AM audio recordings of !Xóõ and Jalapa Mazatec were analyzed. AM recordings can be used, as phase distortion may be neglected while working in the frequency domain. FFT spectra were made of the inverse-filtered waveforms. We considered several questions such as computational methods for deriving the amplitudes of harmonics, the expected dependency of amplitude on frequency, and the appropriate range of frequencies to examine. The results show that measures of spectral tilt obtained from inverse-filtered data can be used to characterize differences in phonation type. [Work supported by NINCDS.]
Aerodynamic and acoustic characteristics of the voicing distinction in electronic larynx speech
Authors: Kobayashi Noriko , Horiguchi Satoshi , Baer Thomas
Published: October 2005

Speech attributes that depend primarily on laryngeal adjustments in normal speech can also be produced by skilled alaryngeal speakers. For example, listeners reliably perceive the consonant voicing distinction in the production of good electronic larynx speakers. In most cases, electronic larynx speech is produced with a continuous sound source regardless of the voicing features of consonants. Therefore, voicing distinctions are evidently not produced by systematic control of voice timing relative to consonantal closure. It has been suggested that electronic larynx speakers use some alternative strategies, such as markedly higher intraoral pressure for voiceless consonants than for their voiced cognates, producing different acoustic patterns for different voicing features. In this study, acoustic and intraoral pressure measurements were made during multiple repetitions of nonsense syllables produced by laryngectomees and normals with and without (transcervical-type) electronic larynges. Different aerodynamic and acoustic patterns pertaining to voicing distinctions in normal and electronic larynx speech were observed. Some specific mechanisms in electronic larynx speech will be discussed. [Work supported by NIH Grant NS13870.]
Vowel spectrum variability due to the source-tract coupling
Authors: Carré René , Guérin Bernard
Published: October 2005

The importance of source-tract coupling on the formant frequencies and bandwidths has already been demonstrated. Moreover, the amplitude of each harmonic component is not stable when the coupling effect occurs (for /a/ vowel for instance) [R. Carré, “Vocal source-vocal tract coupling: effects on the vowel spectrum,” The fourth F.A.S.E. Symposium, Venezia (1981)]. This phenomenon has been studied for male and female vowels (/a/, /i/, /u/) and for increasing and decreasing fundamental frequency. Studies on voiced plosives are in progress. Harmonic amplitude variations up to 20 dB have been observed, the reference being given by covariance techniques during the closed glottis conditions. Consequences for speech synthesis and speech recognition will be discussed.
Modeling study of influences of vocal-tract configurations on glottal behavior
Authors: Bickley C. A. , Stevens K. N.
Published: October 2005

We examined the behavior of a two-mass model of the vocal folds when it is coupled to vocal-tract configurations with various degrees of constriction. More extreme constrictions during vowel-like articulations result in a less peaked and somewhat longer waveform of the glottal volume-velocity pulse, leading to a spectrum with more low-frequency energy. This effect is due to the increased acoustic mass and resistance of the supraglottal airways, as discussed by M. Rothenberg [in Vocal Fold Physiology, edited by K. N. Stevens and M. Hirano (University of Tokyo Press, Japan (1981)], who assumed a fixed glottal area function. The acoustic behavior of the constricted supraglottal tract causes large fluctuations in the pressure in the glottis within a cycle of vibration, and these pressure changes can influence the waveform of vocal-fold displacement (and of glottal area function). Data from the model are discussed in relation to (1) implications concerning the phonetic classification of sonorant segments according to degree of vocal-tract constriction, and (2) the magnitude of these interactions when changes are made in subglottal pressure and in the state of the vocal folds (e.g., male versus female voices). [Supported in part by the Whitaker Foundation and by NINCDS.]
Twitch response of canine vocalis muscle
Authors: Alipour Fariborz , Titze Ingo R.
Published: October 2005

The peak tension and time course of isometric twitch contraction of vocalis muscle in vitro have been measured. Samples of vocalis muscle tissue were dissected and prepared from live dogs in Krebs-Ringer solution at a temperature of about 37 °C. The samples were stimulated with a single square pulse of amplitude 68 V and 2.5-ms duration with a Grass stimulator. Field stimulation was applied with parallel plate silver electrodes and active and passive responses of the sample were obtained electronically with a Cambridge Technology Dual Servo System (ergometer) at various levels of sample length. The twitch characteristics and the relation of physiological length of the muscle to its in-situ length are investigated. It was found that vocalis muscle has a contraction period of 25–30 ms with a latency period of 4–6 ms. [Work supported by NINCDS.]
Vowel acoustics in Parkinsonian dysarthria
Authors: Weismer Gary , Kimelman Mikael D. Z.
Published: October 2005

Motor control deficits in Parkinson's disease may include akinesia and bradykinesia. Whereas these phenomena have typically been demonstrated in the limbs, there is a small amount of evidence [e.g., R. Netsell et al., J. Speech. Hear. Dis. 40, 170–178 (1975), H. Hirose et al., Folia Phon. 33, 204–215 (1981), and C. J. Hunker et al., Neurol. 32, 749–754 (1982)], that these same deficits are present in the orofacial system of some Parkinson's patients. For those Parkinson's patients who have some dysarthria, then, we might expect changes in vocal-tract shape during speech to be both slow and of limited magnitude. These hypothesized speech motor control deficits should be characterized acoustically by a collapsed vowel space, lower-than-normal transition rates, and limited transition extents. Acoustic data from Parkinson's patients with dysarthria, normal geriatric subjects, and normal young adult subjects will be presented to address these hypotheses. [Work supported by NIH Award NS 13274.]
Design considerations for good theatre acoustics
Authors: Lee Lee-Jong , Barron Michael F. E.
Published: October 2005

Despite continued efforts by many researchers, there is little information available for acoustical design of theatres. An investigation, aimed at identifying important design elements was carried out. Extensive objective measurements were made in 12 unoccupied British theatres. Of the objective measures for speech intelligibility, the 50-ms early energy fraction is used in the analysis of the results. The significance of geometrical reflections through the design of ceiling, side walls, balconies, and through the provision of special overhead reflectors has been examined. The effects of directionality of the speaker source in relation to these design elements have also been studied. The results suggest that it would be possible to predict important reflections and thereby the early sound level as a function of design characteristics from architectural drawings. The results of late sound energy have been compared with theory and the agreement was found to be good. The study has found some of the recently completed theatres having low values of the 50-ms early energy fraction. [Work supported by SERC.]
Speech intelligibility prediction in rooms
Authors: Bradley J. S.
Published: October 2005

Three different types of acoustical measures were compared as predictors of speech intelligibility in rooms of varied size and acoustical conditions. These included signal-to-noise type measures, the sound transmission index derived from modulation transfer functions, and useful-to-detrimental sound ratios obtained from early-to-late sound ratios, speech and background levels. The most successful forms of each type of measure were of similar prediction accuracy, but the useful-to-detrimental ratios based on a 0.08-s early time interval were most accurate. Several physical measures, although based on very different calculation procedures, were found to be quite strongly related to each other.
The Pierce 3579b scale
Authors: Pierce J. R. , Mathews M. V. , Reeves Alyson , Roberts Linda A.
Published: October 2005

A new scale, tentatively called the Pierce 3579b scale, has been invented, synthesized, and evaluated. The scale has nine notes spanning a new octave (3:1 frequency ratio). The nine notes are selected from a set of 13 equally tempered half steps, each of which has a frequency ratio of 133. The equal tempered scale gives an excellent approximation to the basic chords which have 3:5:7 and 5:7:9 frequency ratios, the average error being five cents. These chords provide a strong harmonic basis for music written in the new scale because they have high intonational sensitivity—that is, you can hear whether or not they are in tune. Some music has been composed in the new scale, using traditional musical forms such as chorals, canons, and minuets. Many of the compositional techniques used in the diatonic scale appear to have counterparts in the new scale including modulation from one key to another.
An acoustic pulse generator for wind instrument bores
Authors: Ayers R. Dean , Eliason Lowell J. , Salem M. Mongi Ben
Published: October 2005

An inexpensive piezoelectric transducer described earlier [M. I. Ibisi and A. H. Benade, J. Acoust. Soc. Am. Suppl. 1 72, S63 (1982)] is driven by an arbitrary (digital) waveform generator. The width and shape of the volume velocity pulse generated are controlled by Wiener (least-mean-squares) filtering [A. C. Holly, J. Acoust. Soc. Am. 75, 973–976 (1984)]. Using a Harming pulse, or one cycle of a raised sinusoid, we have examined the reflected and transmitted waves that arise at simple discontinuities in bores. One particularly unusual result is an exponentially growing wake in the pressure response to a volume velocity pulse generated at the closed large end of a cone. This wake is required to satisfy the conservation of mass in a closed system, as is also the case for the exponentially decaying wake that arises at the closed small end of a cone [R. D. Ayers, L. J. Eliason, and D. Mahgerefteh, J. Acoust. Soc. Am. Suppl. I 74, S29 (1983).]
Junction inertances and compliances at waveguide discontinuities
Authors: Benade A. H. , Rajkovic M. R.
Published: October 2005

The pressure and flow boundary conditions at the junction of two axisymmetric waveguides may be written pl − pr = jωMlrul and ul − ur = jωClrPl, where the series junction inertance Mlr and shunt compliance Clr arise from the rearrangement of the wavefield in the junction (Mlr >Clr). The predominance of the junction inertance arises from the nonaxial (radial) rearrangement flow, and may be understood in terms of the imaginary wave impedance of the locally excited evanescent modes. Mlr's for the junction of cylinders having unequal diameter, and at the interface between a duct and free space (end-correction) exist in the literature. We have estimated them also for the junction of cylinder and cone, and of two cones. These Mlr's affect the modeling of complex horns as a sequence of cylindrical or conical sections, and do not always go to zero in the many-segment limit which gives the horn equation. For a one dimensional axisymmetric horn with cross section πR2(x), gas density ρ(x), and bulk modulus B(x) the horn equation is normally written ∂2p/∂t2 = (B/R2)(∂/∂x)[(R2/ρ)(∂p/∂x)]. Radial flow effects may be included by multiplyingρ(x) by [1 + δ(x)], where δ depends on |(d2R/dx2)R|. Implications for the inverse scattering and input impedance methods of studying horns of sharply varying cross section will be discussed. [Supported by NSF and American Lung Association (NEO).]
A model of sound propagation from a point source in a lapse temperature gradient
Authors: Van Moorhem W. K. , Cheng Alex , Ma Yiping
Published: October 2005

A model of sound propagation above a finite impedence ground surface with a lapse temperature gradient in the atmosphere has been developed. The model is based on an approximate analytic solution of the wave equation with a variable sound speed resulting from a particular lapse temperature gradient. The solution is expressed in the form of a Hankel transform and inversion of the transform is carried out by the saddle point method for a receiver in the insonified region of physical space and by approximate contour integration in the shadow region. The results obtained are very similar to the experimental results and emperical model of Wiener and Keast [F. M. Wiener and D. N. Keast, J. Acoust. Soc. Am. 31, 724–733 (1959)]. [Work supported by NASA Langley.]
Infrasonic observations of the Direct Course high explosive test
Authors: Whitaker R. W. , Bunker S. S. , Mutschlecner J. P. , Painter C. A. , Bedard A. , Greene G.
Published: October 2005

Direct Course was an experiment involving the detonation of 600 tons of high explosive at the White Sands Missile Range, New Mexico, on 26 October 1983. Direct Course afforded an opportunity for long-range measurements of infrasound propagation. Measurements were made at four stations along a northward bearing from the source at ranges from 250 to 865 km. Each station consisted of an array of sensors covering the frequency range from about 0.1 to 10 Hz. Analysis of signals across an array provide azimuth, horizontal trace velocity, and power spectra of the signal. At the closer stations the signals contain a “precursor” which arrived well before the direct-acoustic-travel arrival time. The principal signal following the precursor region was approximately 13 min in length. Power spectra show the signal to be concentrated in the 0.15-to 1.5-Hz region. Observations of attenuation of the signal and of changes in detailed spectral characteristics are possible with the multi-station observations. Tentative interpretations of the full signal's characteristics have been made with the help of atmospheric and seismic modeling studies.
The background of atmospheric infrasound in the frequency range 0.25 to 20 Hz: Statistical results
Authors: Greene G. E. , Bedard A. J. , Ramzy C. , Khoury J.
Published: October 2005

In reviewing the statistics we treat the data in two passbands. For the lower frequency passband (0.25 to 1.5 Hz) we apply beam-steering techniques to identify the azimuth, horizontal trace speed, dominant spectral peaks, and rms pressure. Magnetic tapes from October 1979 to date contained over 1000 signals. We present several detailed case studies and summary histograms of statistics showing the distributions of azimuth, horizontal trace speed, duration, time-of-arrival, and other parameters. We discuss possible sources for some of these signals. From analyses of sonograph records providing data for a passband covering 1–20 Hz, we categorized over 20 signal types and presently are applying a portable observatory in an effort to identify the origins of local sources. To identify the locations of regional sources (typically at distances >200 km from an observatory) we will work with our colleagues at DOE using bearings from several observatories.
Influence of humidity on sound speed in air at various temperatures
Authors: Wong George S. K. , Embleton Tony F. W.
Published: October 2005

The expected influence of humidity on the speed of sound in standard atmospheric air at various temperatures is presented. The prediction is based on theoretical [G.S.K. Wong and T.F.W. Embleton, J. Acoust. Soc. Am. 76, 555–559 (1984)] and experimental [G.S.K. Wong and T.F.W. Embleton, J. Acoost. Soc. Am. Suppl. 1 76, S65 (1984)] data obtained for the variation of the ratio of specific heats γ in humid air. Over a temperature range from 0° to 30 °C, the maximum uncertainty on the sound speed ratio ch/c0, is estimated to be less than 400 ppm; where ch and c0, are the sound speed in humid and in dry air, respectively. Comparisons are made with known experimental measurements and theoretical data.
Amino acids in inner ear fluids and adjoining compartments (guinea pig)
Authors: Thalmann Ruediger , Comegys Thomas H. , DeMott John E. , Thalmann Isolde
Published: October 2005

We have previously shown [Thalmann et al., Laryngoscope 91, 1785–1791 (1981)] that steep gradients of some amino acids (AA) exist between perilymph, cerebrospinal fluid (CSF), and endolymph. The levels in CSF are either equal to those in perilymph or lower, the most extreme example being glycine (20×lower in CSF). The majority of AAs is lower in endolymph than perilymph, usually by an order of magnitude; however, glutamate and aspartate are higher in endolymph. Most researchers currently consider perilymph to be predominantly an ultrafiltrate of plasma with some interactions with CSF and endolymph. Indeed, the majority of AAs is lower in perilymph than in blood; however, in fasted animals several AAs, most notably alanine, are clearly higher in perilymph, which cannot readily be reconciled with the ultrafiltration theory. To date no well-developed theories about the origin of endolymph have been advanced. It is of interest, though, that while most AAs are far lower in endolymph than in blood, glutamate and aspartate are significantly higher. An attempt will be made to integrate these findings with current notions on the regulation of inner ear fluids and to discuss their potential physiological significance. [Supported by NIH.]
Distribution of sound pressure along the surface of cat tympanic membrane
Authors: Musicant Alan D. , Chan Joseph C. K. , Hind Joseph E.
Published: October 2005

We presented 10-μs clicks free field in a specially treated sound attenuating chamber and measured the distribution of sound pressure as a function of position along the surface of the tympanic membrane. Using the fast Fourier transform, frequencies between 3 and 45 kHz were analyzed. As a probe, about 2–3 mm away from the tympanum, was advanced, sound pressure changes could be detected as a function of location for frequencies above about 12 kHz. These differences were essentially monotonic as the probe was advanced antero-ventrally. Pressure differences reached 12 dB at some frequencies. A second probe, placed at right angles to the first and fixed in position at the canal wall, was used to monitor pressure as the first probe advanced. Detectable pressure changes were small, less than 2 dB, indicating that the advancing probe did little to disturb the sound field, at least at the wall of the canal. As the second probe was advanced perpendicularly to the malleus (dorso-anteriorly), little detectable change was found when the probe was greater than 0.5 mm from the canal wall. We also attempted to determine the pinna amplification function for a sound source on the pinna axis. While a complex, frequency dependent pattern emerges, with some very sharp, deep minima many frequencies up to 45 kHz were amplified 15–20 dB. In addition, measurement of the pinna amplification function, using a probe placed inside the pinna and near the entrance of the auditory meatus, indicated a critical dependence upon positioning of the probe. When small changes (1–2 mm) in the placement of the probe were made, pressure differences of as much as 15 dB for frequencies above 15 kHz were detected. Pressure differences of 5–10 dB at 4 kHz were also detected when the probe was moved 3–4 mm. [Supported by NIH grants NS 12732 and NS07026.]