bluuebunny/crossref_metadata_2025 huggingface dataset:
Voids in the gerbil cochlear nucleus: Is there an anatomical substrate for intensity coding?
Authors: Statler K. D. , Chamberlain S. C. , Smith R. L. , Slepecky N. B.
Published: October 2005

The presence of voids in the gerbil cochlear nucleus has been reported by Morest et al. [IUPS Satellite Symposium on Hearing Abstract, p. 80 (1986)] and related to some aspects of auditory experience by McGinn and Faddis [Hear. Res. 31, 235–244]. The number, volume density, and void size were investigated in animals of various ages from 18–485 days. These variables were found to increase as a function of age with a maximum volume density of about 1% [Statler et al., ARO Abstracts, p. 209 (1988)]. The spatial distribution of the number of voids in the cochlear nucleus was computed as a function of the incoming neural activity produced by ambient noise over the life of the animal. In a three-dimensional reconstruction, the voids form a contiguous area in the granular layer and posteroventral cochlear nucleus. The anteroventral cochlear nucleus and dorsal cochlear nucleus are spared. The number of voids was found to be a monotonically increasing, negatively accelerated function of the total neural activity. The difference between the void distribution and tonotopic organization of the cochlear nucleus leads to the interesting possibility that the spatial distribution of voids corresponds to the low-intensity portion of the tonotopic regions of the cochlear nucleus and the void distribution reflects an anatomical substrate for intensity coding.
Effect of an acoustic wave on mean-flow stability
Authors: Thompson Charles , Manley Martin
Published: October 2005

The interaction between an acoustic wave and a mean flow near the surface of a bluff body will be discussed. The base flow solution will be presented. A nonlinear analysis will be used to find the region of validity of the linear stability solution. Nonlinear effects will be shown to stabilize disturbances outside the stagnation point region.
Mode coupling caused by a mesoscale oceanic eddy
Authors: Shang E. C.
Published: October 2005

From the full-wave theoretical point of view, there are two regimes for the interaction of acoustic waves with an oceanic mesoscale eddy: the weak coupling regime and the strong coupling regime. Understanding the limits of these two regimes is crucial for developing the new generation of ocean acoustic tomography systems based on the full-wave theoretical framework instead of ray theory. In the present paper, the mode coupling caused by an oceanic mesoscale eddy is investigated by numerical simulating on CYBER 205. The eddy is modeled as a Gaussian eddy with parameters: DR (horizontal scale), DZ (vertical scale), ZE (center depth), and DC (strength). By incorporating a single-mode starting field into a 2-D PE (IFD) code, mode coupling coefficients are given by a mode filtering processing after passing through the eddy. Mode coupling coefficients are calculated for a frequency range of 10–100 Hz, and a mode number range of 1–10. It has been found that the mode coupling has a complex “resonant feature” with eddy parameters and also has a dependence on frequency as well as on mode number. However, the limit of the weak coupling regime, within which the adiabatic mode theory is valid, can be drawn out but it is by no means a simple criterion. [Work supported by NOAA.]
Large area sensors for active acoustic control systems
Authors: Howarth Thomas R. , Bao Xiaoqi Q. , Varadan Vijay K. , Varadan Vasundra V.
Published: October 2005

The design and development of a composite piezoelectric polymer (PVDF) sensor for use in an active acoustic control system are presented. Large area PVDF plates are encapsulated in a polymer matrix to detect both the incident and reflected signals in an underwater pulse tube at low frequencies. These signals are amplified, phase shifted, and then used to drive an absorbing transducer to negate reflections. The results of this system are compared with earlier data [X.-Q. Bao, V. K. Varadan, and V. V. Varadan, J. Acoust. Soc. Am. Suppl. 1 84, S49 (1988)] that utilized piezoceramic spherical hydrophones. [Work supported by the Research Center for the Engineering of Electronic and Acoustic Materials.]
Construction of a mathematical model of the nonlinear, dynamic mechanical properties of unreinforced masonry
Authors: McNiven Hugh D.
Published: October 2005

This presentation reports the results of a study of the construction of a mathematical model for predicting the nonlinear in-plane behavior of clay brick masonry walls when subjected to dynamic excitations. The construction consists of two stages: first the development of the form of the model and then the establishment of the parameter functions appearing in it using experimental data and system identification. In previous work with system identification, it was learned that there are several advantages if the system to be modeled is linear. The optimization is easy and cheap because the iterations minimizing the cost function converge rapidly. Perhaps, even more important is the fact that the transfer function itself is optimized rather than the time response of the model to a particular input, as is the case with nonlinear modeling. Experiments consist of subjecting twin walls of masonry to earthquake excitations on the shaking table at the Earthquake Engineering Research Center (EERC), University of California at Berkeley. The experiments were designed so that the structure was subjected to a series of earthquake inputs of increasing intensity, but so that consecutive intensities differed by a small amount. As a result, the response to an individual excitation, even in the nonlinear material domain (following cracking), is almost linear. It was assumed that the wall would behave isotropically. The subsequent form of the model left two parameter functions to be established, one describes elastic-plastic stresses and depends on strains; the other describes viscous stresses and is a function of strain rates. Experimental data and system identification, using a particular optimization algorithm, showed that both the shear modulus of the masonry and its associated damping factor are bilinear. The experimental time histories of acceleration and displacement were compared with those predicted by the completed model. Even in the highly nonlinear range of material behavior, the two responses were unusually close.
The perception of English vowels by native speakers of Spanish
Authors: Flege J. E. , Bohn O.-S.
Published: October 2005

This study examined native Spanish speakers' perception of four English vowels (/i, ɪ, ɛ, æ/). In experiment 1, subjects used letters (〈i,e,a,o,u〉) to identify the vowels in beat, bit, bet, bat or responded “none” if they did not hear a Spanish vowel. The pattern of responses was unsurprising: mostly 〈i〉 for the English vowels /i/ and /ı/, 〈e〉 for the English /ɛ/s, and 〈a〉 for /æ/. Subjects who could speak English responded “none” significantly more often than Spanish monolinguals for all four words, suggesting they had begun to differentiate the English vowels from their nearest phonemic counterpart in Spanish. In experiment 2, subjects identified the members of continua which varied spectral quality (11 steps) and vowel duration (3 steps). Like native speakers, most Spanish subjects showed clear crossovers when identifying stimuli ranging from /bɛt/ to /bæt/, probably because the contiuum endpoints were identified with different Spanish vowels (viz., /e/ and /a/). Only six (30%) of the Spanish subjects, however, showed clear crossovers for a /bit/-to-/bɪt/ continuum, probably because the endpoints were identified with reference to a single Spanish vowel (/i/). The pattern of identification responses did not change systematically when stimuli differing in spectral quality were blocked on vowel duration in experiment 3. The results were interpreted to mean that even experienced Spanish speakers of English may not establish phonetic categories for “new” English vowels such as /ɪ/ and /æ/. [Work supported by NIH Grant 20963.]
Experimental evidence for the unit of bird song production
Authors: Cynx Jeffrey
Published: October 2005

An experimental procedure was developed to determine the real-time nature of birdsong production. In a given trial, a burst of strobed light, directed at a male zebra finch (Poephila guttata), was triggered at a random point in his courtship song. Repeated trials allowed the formulation of three rules governing song production: (1) A zebra finch can stop song production in the midst of song, (2) the motor unit for song production is quantal, and (3) the quantal unit of song production is largely identical to a syllable, as read off a sound spectrogram. The comparative generality of the rules was tested by replicating results with another two other oscine species, the song sparrow (Melospiza melodia) and the canary (Serinus canarius). The results place constraints on neural models of song production, and suggest invariance between the units of song perception and production. [Research supported by NIH and the Cary Charitable Trust.]
A comparison between low-frequency sound absorption in seawater and high-frequency sound absorption in serum albumen
Authors: Browning David G. , Mellen Robert H.
Published: October 2005

Although large scale (> 1000 km), low-frequency (<20000 Hz) sound absorption measurements in seawater [Mellen et al., J. Acoust. Soc. Am. 74, 987–993 (1983)] might appear to have nothing in common with high-frequency sound absorption in serum albumen [Barnes et al., J. Acoust. Soc. Am. 83, 2393–2404 (1988)], the results show some intriguing similarities that may be due to a common chemistry. Specifically, both show a pH dependence, a buffered reaction involving a carboxyl group, and the need of calcium to promote the principal reaction. However, boric acid, which is essential for seawater absorption, is apparently not a factor in serum absorption. A comparison is presented in the hope of stimulating a dialogue with the bioacoustics community to explore a possible linkage.
The influence of biophysical conditions on hemolysis near ultrasonically activated gas-filled micropores
Authors: Miller Douglas L. , Thomas Ronald M.
Published: October 2005

Hemolysis in 0.5% suspensions of canine erythrocytes exposed to 1.9-MHz ultrasound in the presence of 3.7-μm-diam gas bodies in filter micropores (Nucleopore®) was investigated as a function of spatial peak intensity for varied biophysical conditions. Significant hemolysis was observed above 90 mW/cm2, which increased to 50% at 500 mW/cm2, for 30-min exposure at 37 °C in isotonic phosphate buffered saline. Hemolysis increased with exposure duration (4–64 min) but did not greatly change with exposure temperature (25, 37, 48 °C), or prior heat treatment (48 °C for 30 min). The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the shear stress generated in acoustic microstreaming flow near the ultrasonically activated gas bodies. Increasing the viscosity (1, 2, 4 cP) of the medium decreased the effect, while variations in osmolarity (180, 290, or 580 mOsm) or density (1.03 or 1.12 g/cm3) had little influence on the results. Increasing the density of the medium might have been expected to reduce the effectiveness of the exposures, since the radiation force, which theoretically gathers cells to the gas bodies, vanishes for isopycnic conditions. [Work supported by PHS Grant CA42947 awarded by the National Institutes of Health.]
Cues to perceptual normalization of talker differences
Authors: Morin Todd M. , Nusbaum Howard C.
Published: October 2005

To recognize vowels produced by a specific talker, a listener must know something about the talker's vowel space. How do listeners learn about a talkers' vowel space? How different must two talkers' vowels be to constitute different vowel spaces? To investigate these questions, listeners monitored sequences of target vowels for a specified target. In one condition, a single talker produced the vowels for each trial. In a second condition, a mix of four talkers produced the vowels for each trial. Previous research demonstrated that vowel recognition is accurate when talkers are mixed, but it requires more attention. The present study compared recognition for whispered and voiced vowels in these conditions to eliminate the use of F0 as a cue for talker normalization. Another experiment examined the effects of talker differences on normalization. Performance for a pair of talkers with similar vowel spaces was compared to performance for a pair of talkers with more disparate vowels. The results of these studies indicate the importance of fundamental frequency in vowel recognition across talkers and that the amount of effort required for normalization of talker differences depends on the similarity of the different talkers' vowel spaces. [Work supported by NIH.]
On the perceptual representation of vowel categories
Authors: Johnson Keith
Published: October 2005

Subjects' behavior in a vowel perception task was compared with the predictions of two different types of vowel perception models. Both models use auditory spectra generated by a model of the peripheral auditory system [Bladon and Lindblom, J. Acoust. Soc. Am. 69, 1414–1422 (1981)]. In the first model, it is assumed that the spectral information in vowels is represented as a whole spectrum. The spectral characteristics of a vowel category are modeled as a spectral template against which incoming vowel spectra are compared. In the second model, the spectral information in vowels is characterized by the frequency locations of spectral peaks. Here, the spectral component of a vowel category is taken to be information concerning the frequencies of spectral peaks. Two sources of vowel templates for the models were also compared. In one case, templates were derived from the subject's own productions of the vowels in question. In the other, templates were derived from vowels synthesized with average formant values reported by Peterson and Barney [J. Acoust. Soc. Am. 24, 175–184 (1952)]. Subjects were instructed to find the best exemplars of each of 11 different vowel categories from an array synthetic steady-state vowel tokens by adjusting the F1 and F2 of the tokens until the best exemplar was located. In all cases, it was found that the whole spectrum approach provided the best fit to the subjects' perceptual judgments. It was also found that model predictions based on the Peterson and Barney vowels provided a better fit to the perceptual data than did predictions using the subject's own productions as the basis for spectral templates. This finding suggests that perceptual vowel categories are not subject to the idiosyncrasies of the individual's own speech production, but rather are a product of the listener's range of the perceptual experience.
Training methods for the facilitation of Japanese students' perception of American English /r/ and /l/
Authors: Miranda Salvatore , Underbakke Melva , Strange Winifred , Micceri Theodore
Published: October 2005

This study investigated the effects of two types of discrimination training on the perception and production of /r/ and /l/ by Japanese students of English. Training stimuli cansisted of synthetic syllables drawn from three different ten-step /r/-/l/ series: rock-lock, rake-lake, and rook-look. The prototype group received discrimination training using only the endpoint stimuli from each series (the clearest instances of /r/ and /l/). The gradient group received discrimination training that began with the endpoints and proceeded gradually to stimuli near the (English) category boundaries. Control subjects received discrimination training on naturally produced tokens of /b/ vs /v/ (another contrast that Japanese find difficult). Comparisons of pre-test and post-test scores showed improvement for both prototype and gradient groups in identification of synthetic speech series and in production, but not in perception of naturally produced minimal pairs. Improvement for the control group was restricted to the perception of the synthetic /r/-/l/ series. No differences were found in the overall effectiveness of prototype versus gradient training. [Supported by NINCDS.]
Perceptual characteristics of English syllable-initial /r,l/ for Japanese listeners
Authors: Yamada Reiko , Tohkura Yoh'ichi , Kobayashi Noriko
Published: October 2005

This study investigates the perceptual characteristics of American English /r,l/ for Japanese listeners using synthesized stimuli. Five major findings are obtained. (1) The Japanese listeners identify the stimuli using a variety of acoustic cues, and their response patterns are strongly influenced by acoustic features of the stimuli. In contrast, the American listeners can identify /r/ and /l/ as long as a primary cue remains, even under the condition where some of the acoustic cues are missing. (2) As the Japanese listeners tend to perceive some stimuli as /w/ more than American listeners do, perception experiments with /w/ as well as /r/ and /l/ for a choice of identification better clarify the perception mode of the Japanese listeners. (3) A positive relationship between the identification ability of the natural /r,l,w/ spoken by native Americans and that of the synthesized /r,l,w/ is found for the Japanese listeners. (4) Contextual effects in words are very strong for the Japanese listeners when trying to identify /r/ and /l/. (5) The Japanese listeners who have lived in English-speaking countries before a certain age are able to identify /r/ and /l/ as well as native Americans.
Physical bases for Arctic ambient noise
Authors: Dyer Ira
Published: October 2005

The fundamentals of noise generation by ice fracture processes such as occur in the Arctic Ocean are reviewed. Noise events, presumably associated with individual ice fractures, are measured and studied in terms of their source strengths, characteristic frequencies, event signatures, event densities, and ice morphologies. A usefully narrow set of possible mechanisms seems to be emerging as a plausible explanation for a wide variety of cases. [Work supported by ONR Arctic Acoustics Program.]
A continuous-wave reflection bridge ultrasonic spectrometer constructed from off-the-shelf components
Authors: Sundfors Ronald K.
Published: October 2005

A versatile continuous-wave reflection bridge ultrasonic spectrometer has been developed. This spectrometer features simple tuning of the bridge element (commercial hybrid junction) for frequencies up to 100 MHz, a wide variation of applied acoustic power, simple computer control to lock frequency to any point of the acoustic response, diode and phase coherent detection, sensitivity equivalent to the best nuclear acoustic resonance spectrometers, and construction from off-the-shelf components. Use of the spectrometer as a cw spectrometer, sampled-cw spectrometer, and NAR spectrometer will be discussed.
Effects of focusing on the scattering of sound by sound
Authors: Darvennes Corinne M. , Hamilton Mark F. , Tjøtta Jacqueline Naze , Tjøtta Sigve
Published: October 2005

The effects of absorption on the scattering of sound by sound were discussed by the authors at the previous meeting [J. Acoust. Soc. Am. Suppl. 1 85, S5 (1989)]. In the present paper, the effects of focusing are considered. The Khokhlov-Zabolotskaya-Kuznetsov equation is used to derive asymptotic results for the sum and difference frequency sound that is generated by the noncollinear interaction of focused sound beams radiated from displaced Gaussian sources. As in the case of unfocused primary beams, there are two main contributions to the nonlinearly generated sound field: pumped sound and scattered sound. Attention is devoted to the effects of focusing on the relative and absolute levels of the pumped and scattered waves. Strong focusing causes the pumped and scattered sound fields to broaden and overlap, which increases the difficulty of identifying the scattered sound. Numerical results are presented. [Work supported by ONR (CMD and MFH), IR&D Program of ARL:UT, and VISTA/STATOIL (JNT and ST).]
Critical behavior of the ultrasonic attenuation and velocity and shear viscosity for the binary mixture of nitrobenzene-n-hexane
Authors: Abdelraziq I. R. , Yun S. S. , Stumpf F. B.
Published: October 2005

Ultrasonic velocity and absorption and shear viscosity as a function of temperature and frequency are reported for the binary mixture nitrobenzene-n-hexane in the homogeneous phase above Tc. The observed absorption αc/f2 vsf f−1.06 yields a straight line as predicted by the dynamic scaling theory of Ferrell and Bhattacharjee. The critical amplitudes of the thermal expansion and specific heat have been calculated using the two-scale factor universality relation. The adiabatic coupling constant g is calculated and compared to the experimental value. The experimental values of α/αc for nitrobenzene-n-hexane are compared to the scaling function F(ω*) and show a good agreement with the theory. The velocity for the system at the critical concentration above the critical temperature appears to linearly decrease with increasing temperature.
A performance-oriented approach to the hearing of complex sounds: Nonspeech and speech
Authors: Watson Charles S.
Published: October 2005

Two general questions have been addressed with experiments using word-length tonal sequences, or “patterns”: to what degree can the discriminability of complex auditory patterns be predicted from listeners' performance with simpler stimuli, especially single tones presented in isolation? and, (2) How do listeners' abilities to extract information from complex nonspeech sounds compare to their abilities to resolve the details of the waveforms of speech? The answers appear to be consistent with the results of comparable investigations conducted for the past half-century in the field of vision. Very little degradation in sensitivity or resolving power for components of complex sounds can be attributed to the complex stimulus context per se, aside, of course, from temporal masking. When patterns vary from trial to trial, selective attention and accurate discrimination performance can be achieved only when prior experience has made them so familiar that processing has become “automatic.” Listeners' remarkable resolving power for speech sounds can readily be imitated by overtraining them on the discrimination of at least some nonspeech sounds.
Auditory profile analysis
Authors: Green David M.
Published: October 2005

Data are reported on the ability of listeners to discriminate changes in the power spectra of complex acoustic signals. Since randomizing both the phase spectrum and the overall level of the signal on each presentation does not change detection performance, it is known that detection is not based on the signal's phase spectrum or the absolute level of energy at a particular frequency location. The discrimination must be based on a change in the shape of the power spectrum of the signal, what is called profile analysis. The most critical feature of profile analysis is that detection of a change at one spectral location depends on energy at very remote spectral locations. For example, the detection of an increment in the intensity of a component at 1000 Hz is influenced by the presence or absence of energy more than 2 oct away. Recent experiments show that these effects may depend on whether the standard power spectra are fixed or changing over successive trials, since spectra with randomly changing levels do not show such effects. Finally, some recent experiments will be discussed that provide estimates of the spectral weights employed by profile listeners, using a technique developed by Dr. Bruce Berg. [This research was supported by NIH and AFOSR.]
Factors in detection under uncertainty
Authors: Hafter Ervin R. , Schlauch Robert S.
Published: October 2005

An especially effective tool for examining cognitive factors in hearing is the study of masking under conditions of uncertainty. Past studies of frequency uncertainty and its alleviation with cues leads to the proposal that the role of attention in detection is to govern the trade-off between the number of monitored bands and their effective bandwidths. In an extension of that work, attempts to measure the bandwidths directly and to understand the nature of cuing are made, whether it is a bottom-up process, as in the ringing of sensory filters, or top-down, as in the selection of the appropriate filter. Two distinct approaches are offered. In one approach, a modified “probe” technique presents a cue of either 1, 2, or 4 tones which includes, on most trials, the frequency of the signal; on probe trials, the signal is some fixed percentage (other than 100%) of the frequency of one the cues. Performance based on data collapsed across equal percentages support the contention that changes occur in both effective number and bandwidth. Additional studies examine cues that require higher-order processing such as computation of musical interval or fundamental pitch. The effectiveness of these cues supports the notion of top-down processing. [Research supported by Grants from NINCDS.]
Cross-sectional tongue shapes and palatal contours during sibilant and lateral consonants
Authors: Stone Maureen , Raphael Lawrence J. , Faber Alice
Published: October 2005

This presentation will examine the relationship between tongue shape and palatal contour during the production of /s/ , /∫/, and /l/. A combination of electropalatoraphy (EPG) and ultrasound (US) was used to compare tongue-palate contact patterns with their related cross-sectional tongue shapes. The phonemes /s/, /∫/, and /l/ are interesting to study because they are physiologically demanding. They necessitate distinct posterior tongue shapes to channel the air anteriorly (sibilants) or laterally (/l/). In addition, these phonemes exhibit specific palatal contact patterns that result in their unique acoustic waveforms. Another effect of tongue-palate contact, which is usually overlooked, is the resultant bracing of the tongue. With the anterior tongue braced against the alveolar ridge, the posterior tongue is able to deform into a variety of cross-sectional shapes (concave for /s/, convex for /l/).
Articulatory and acoustic analysis of consonants differing in intelligibility
Authors: Bunnell H. Timothy
Published: October 2005

Articulatory and acoustic recordings of a single talker producing multiple repetitions of nonsense utterances were made at the University of Wisconsin X-Ray Microbeam facility. The utterances consisted of the fixed frames “Say a Cawa” and “Say a waCa” with C = {/b/, /d/, /g/}. Each utterance was repeated three times in each of three speaking styles ranging from an exaggerated style intended to be “clear” (i.e., easier for the hard of heating to understand) to a relaxed style intended to be “conversational.” The audio recordings were presented to hearing impaired listeners in a three-alternative forced-choice stop consonant identification task to determine the relative intelligibility of the stop consonants. By hypothesis, the clearest consonants would be found in utterances that exhibited the greatest amounts of articulatory and acoustic change. However, this pattern was not found. For utterances with syllable-initial consonants (e.g., “Say a gawa”), actual intelligibility as estimated by percentage correct stop constant identification was inversely related to both the talkers intent and measures of the extent of articulator motion. Correlational analyses using both articulatory and acoustic measures to predict obtained intelligibility scores will be presented. [Work supported by NIH.]
Speech movement coordination: Oral-laryngeal interactions
Authors: Gracco Vincent L. , Lofqvist Anders
Published: October 2005

Kinematic investigations of speech motor actions have revealed elegant examples of coordinative motor control principles that reduce the degrees of movement freedom. For example, recent studies of upper lip, lower lip, and jaw movements for oral closure have demonstrated a temporal organization similar to rhythmic motor behavior such as locomotion. Consistent temporal coupling among multiple articulators is maintained and systematically scaled following unexpected mechanical perturbations of the lower lip or experimental manipulations of the phonetic environment. In order to generalize these apparent coordinative principles to include other phonetic environments and articulatory subsystems, the present study investigated the adjustments underlying lip, jaw, and vocal and vocal fold movements associated with various voiceless sounds. Movements of the upper lip, lower lip, jaw, and vocal folds were recorded. Kinematic measures, including relative timing among jaw, upper/lower lip, and glottal opening/closing (devoicing) movements were obtained. Results demonstrate that coordinative timing relations among the multiple articulators are systematically scaled as a function of movement speed and phonetic context. Thus, consistent relative timing among functionally related articulators is a general property of speech movement coordination. It is hypothesized that such a constraint while simplifying the motor control process can provide sufficient kinematic variability while maintaining the underlying synergistic organization. [Work supported by NIH.]
Remote and local effects of stress within and among articulatory subsystems
Authors: Fowler Carol A. , Gracco Vincent , Vatikiotis-Bateson Eric
Published: October 2005

Previous research on stress has focused almost exclusively on articulatory correlates local to a single target syllable within a single articulatory subsystem (e.g., the lip-jaw or the respiratory system). However, the articulatory correlates of stress are not local in either sense. Although a few studies report remote effects of stress (effects not confined to the stressed segment) on the speech acoustics, articulatory studies have reported the effects of stress only for single subsystems (e.g., oral, laryngeal, and respiratory); there have been no systematic investigations of the extent to which stress effects are manifest throughout the speech production system. The present study investigates the effects of stress in the vocal tract and respiratory system. Lip and jaw and respiratory kinematics, laryngeal vibration, and intra oral air pressure were simultaneously recorded during recitation of sentences in which lexical, contrastive, or sentential (focus) stress were varied. Changes in the articulatory kinematics and in the relative timing of laryngeal, respiratory, and supralaryngeal activity are analyzed as a function of stress type and position in the utterance. Results suggest that the articulatory correlates of stress are distributed continuously within and across subsystems. [Work supported by NIH.]
Analysis of deaf speakers' breath stream dynamics during speech production
Authors: Mahshie James J. , Yadav Pradeep K.
Published: October 2005

Computer simulations have been used to characterize and better understand the articulatory behavior of normal [M. Rothenberg, Biblio. Phon. (1968); E. Muller and S. Brown, Speech Lang. (1980)] and disordered [V. Gracco and E. Muller, ASHA 13 (1981)] speakers. In the present work, details of a computer simulation of breath stream dynamics of speech produced by deaf speakers will be presented. Oral airflow, oral air pressure, nasal airflow, electroglottograph, and acoustic data were acquired from both deaf and normal speakers during production of intervocalic bilabial plosives. Measures from these data were used to establish input parameters for simulation of both the deaf and normal-hearing speakers' utterances. Among the parameters manipulated in the model were: airflow resistance at the articulatory constriction, nasal tract resistance, vocal tract enlargement, and glottal resistance. Pressure and flow outputs from both the simulations and speakers were compared. Advantages and limitations of the use of computer models to understand speech production processes of disordered speakers will be discussed. [Work supported by the Whitaker Foundation.]
Palatography: A comparison between custom-made and “flexible” artificial palates for speech production measures
Authors: McGart Nancy S. , Tsunoda Koichi , Harris Katherine S.
Published: October 2005

While dynamic palatography, a method of measuring tongue-palate contact over time, has a long history, the method has seen limited use because of the need to custom-make a palate for each subject. Recently, the Rion Company has developed a “universal” semiflexible palate, with 64 contact points, in several sizes. This methodological study was designed to assess the comparability of data from flexible and custom-made palates, and the stability and reliability of flexible palate measures. Three speakers repeated multiple tokens of /isi/ and /asa/ with both palate types, and with flexible palates removed and replaced. While test-retest reliability was satisfactory for flexible palates, the custom-flexible comparisons revealed the need to develop measures of subject-to-subject differences in palate size and shape, if the technique is to develop its potential for large-scale studies of articulation in normal and clinical populations. Comments will be made on analysis software, sampling rate, and contact-point distribution. [Work supported by NIH Grant NS-13617.]
Optimum bearing resolution for a moving towed array and extension of its physical aperture
Authors: Stergiopoulos Stergios
Published: October 2005

This paper examines the limits of the angular resolution capability of a moving towed array (MTA) by finding the Cramer-Rao lower bounds (CRLB) and providing algorithms that extend the physical aperture of an MTA. The model that is considered for the CRLB estimates assumes that an M-hydrophone towed array is moving with known constant speed and that in the received signal unknowns are all the parameters for two sources. The estimated CRLBs for this model indicated that an M-hydrophone MTA provides very high angular resolution when the period T of the received signal is very long. This ability of the moving array to resolve two closely spaced sources is related to the fact that the physical aperture has been extended by the distance traveled by the array during the T seconds of the observation period. Computer simulation examples using the maximum likelihood estimator and an extended towed array algorithm (ETAM) to find the bearing of the sources are presented. The results of these simulations agree with the CRLB if the signal-to-noise ratio (SNR) is higher than 0 dB at the hydrophone level of-8 dB re: 1-Hz band. Real data applications using the ETAM were successful, and the physical aperture of a 32-hydrophone MTA was extended to an equivalent of a 512-hydrophone fully populated array during 185 s of observation period. These results have also indicated that the performance of the above algorithm is very robust since it extends the physical aperture of an array by more than one order of magnitude for the case of a very low SNR broadband signal even though the source had 3.6-kn speed along its bearing.
A new method for passive synthetic aperture array processing
Authors: Sullivan Edmund J. , Stergiopoulos Stergios
Published: October 2005

A technique for extending the useful aperture of a towed array is presented. Its advantage over previous techniques is that it uses the existing aperture of the physical array to estimate the phase correction factor for the successive measurement. Thus the need for an accurate knowledge of the source frequency is avoided. By using the fact that, at any time, the array overlaps its position at a previous time, a maximum likelihood estimator can be constructed that computes the phase difference between the measurements taken at these two positions. This estimated phase difference is then used to correct the second measurement. An iterative procedure is then used to extend this technique over several measurements. This estimation procedure, along with estimating the kinematic phase correction factor ωτ includes any other phase errors that may be incurred by such effects as array motion, propagation effects, or loss of temporal coherence. Results with both real and synthetic data arc shown that demonstrate that the technique significantly outperforms previous techniques.
Scattering of sound by atmospheric turbulence
Authors: McBride Walton E. , Bass Henry E. , Respet Richard , Gilbert Kenneth E.
Published: October 2005

A computer simulation of the effect of small scale turbulence on atmospheric sound propagation over a complex impedance boundary is developed. The atmosphere is broken up into spherically symmetric eddies characterized by a Gaussian profile. Single scatter is assumed and a closed form of the first Born approximation for scattering is obtained, giving each eddie's contribution to the total fluctuation of the sound pressure at a receiver downrange. The numerical simulation was accomplished with the concept of a “realization,” or snapshot of the turbulent medium. Each eddie's scatter contribution was added up for a particular configuration of eddies, giving that realization's total sound pressure fluctuation. The eddies were then given a random change in their coordinates. The total sound pressure was calculated for this realization, and the process repeated. A complex impedance boundary was added and the predictions of the standard deviations of the amplitude fluctuations, amplitude probability distributions, and structure functions were then tested against experimental data. Good agreement was found whenever the average intensity of the fluctuations was well above the background noise level. [Work supported by U. S. Army Construction Engineering Research Laboratory.]
Auditory-filter shapes at three test frequencies with a burst and a fringed notched-noise masker
Authors: Wright Beverly A.
Published: October 2005

The shapes of the auditory filters centered at 0.5, 1.0, and 3.0 kHz were determined using Patterson's notched-noise method, but with the onset of the tonal signal delayed either 1 ms (burst condition), or 350 ms (fringed condition) after the onset of the masking noise. The masking noise ranged from 0.1–10.0 kHz, and its spectrum level was 24 dB. All waveforms were gated with a rise/fall time of 10 ms, and the offset of the signal always preceded the offset of the noise by 2 ms. Although there were individual differences across listeners, for all six of them, the filters at the three test frequencies were narrower in the fringed than in the burst condition. In general, the differences in the filter shapes in the two conditions increased as the signal frequency increased. In accord with unpublished work of R. Carlyon, the narrowing process was complete with signal delays of 50–100 ms and was observed for signal durations of 25 and 50 ms, but not for a signal duration of 200 ms. Possible underlying mechanisms will be discussed. [Work supported by NINCDS.]
Acoustic characteristics of Xhosa clicks
Authors: Sands Bonny E.
Published: October 2005

Xhosa, a Bantu language of Southern Africa, has 15 distinct clicks. Clicks are made at three places of articulation—dental, alveo-palatal, and lateral—and with five different accompaniments—voiceless, aspirated, nasalized, murmured, and nasalized murmured. A recording was made of eight speakers saying words containing each of these 15 clicks before each of the five vowels /i,e,a,o,u/. The DSP Sona-Graph was used to produce wideband spectrograms, waveforms, and spectra of these utterances. Dental clicks were marked by fricative noise occurring throughout a wide frequency range, and by lack of a clear onset. Alveo-palatal clicks were marked by an abrupt release with little frication. Lateral clicks were more affricated than the alveo-palatal clicks. The place of articulation of the click was not observed to have any effect on the formant transitions of the following vowel. Observed vowel effects on clicks were limited to the reduction in amplitude of high-frequency noise before rounded vowels /u/ and /o/. The five accompaniments at each place have a number of phonetic characteristics that will be discussed. [Work supported by NSF.]
Higher harmonics and formants analysis of speech signals
Authors: Coronel Victor F. , Catto Sultan
Published: October 2005

Spectral analysis of windowed segments (12.8–52.8 ms in duration), of the approximately steady portion of vowel sounds, in the context CVC, was analyzed for several individuals at various SPL levels for each subject. It was observed that the signals with larger SPL values were much richer in harmonics and formants. A relation between the straining of the vocal cords and the higher harmonics is established and its relation with nonlinear models of the vocal chords and vocal tract examined. The higher harmonics of the fundamental frequency, sixth and above, and the higher order formants, third and above, when present for certain vowel sounds, may be of particular importance as diagnostic tools in vocal-fold-vocal-tract clinical examination.
Automatic correction of formant tracks: A progress report
Authors: Fingerhut J. Andrew , Miller James D.
Published: October 2005

Since commercially available formant trackers are often inconsistent, much hand-editing is required to correct their outputs. A software package is currently being developed that may reduce this problem. Two female and two male speakers were recorded producing ten vowels in S-vowel-T context, each vowel twice. Boundaries between burst-friction, glottal-source, and silent segments are located using zero crossing and rms energy measurements. Pitch and formant-frequency values are extracted using the API and SGM commands of ILS. Our software corrects the pitch contour and calculates a sensory reference from it [J. D. Miller, J. Acoust. Soc. Am. 85, 2114–2134 (1989)]. Rules based on the relation between peak frequencies and this sensory reference are utilized to label the peaks as formants and the resulting formant tracks are then low-pass filtered. In this way, satisfactory tracking is obtained for all 80 syllables. [Work supported by AFOSR and NIDCD.]
Accurate measurements of jitter, shimmer, and glottal turbulence noise from sustained vowels
Authors: Kasuya Hideki , Kikuchi Yoshinobu , Huang Zaoming , Komuro Osamu , Maeda Keisuke
Published: October 2005

There has been much research on the measurement of jitter, shimmer, and glottal turbulence noise from sustained vowels, primarily aiming at acoustic quantification of pathological voices. Many problems remain unsolved, however, specifically those of accurate methods for the pitch extraction and noise measurement and of quantification of shimmer. This paper describes a sophisticated method for the pitch period determination based on a cycle-to-cycle similarity of the waveform and a novel method to quantify shimmer characteristics. In this method, shimmer is analyzed for the individual harmonic component of the waveform in terms of its variations in amplitude and phase characteristics. Acoustic measurements of glottal turbulence noise due to insufficient vocal-fold closure are also discussed. Efficacy of the new methods for the measurement of jitter, shimmer, and noise is compared with previous work using pathological voice samples. [Work supported by a Grant-in-Aid from the Ministry of Education, Science and Culture, Japan.]
Effects of temporal position on the detectability of interaurally uncorrelated noise
Authors: Rickert Martin E. , Robinson Donald E.
Published: October 2005

Listeners' ability to detect an interaurally uncorrelated segment of noise within binaural broadband noise bursts was measured as a function of the temporal position of the uncorrelated noise. Psychometric functions were obtained by varying the duration of uncorrelated noise. The results indicate that detectability improves as the duration of uncorrelated noise is increased. Temporal position affected detectability only at the shortest durations of uncorrelated noise tested; a segment positioned either at the end or at the beginning of the burst is more detectable than one in the middle. This result is not easily accounted for by models of binaural processing. For example, the EC model [N. I. Durlach, J. Acoust. Soc. Am. 35, 1206–1218 (1963)] assumes that performance is determined by the power of the difference in the waveforms in the two auditory channels. Since power is computed over the total stimulus duration, it is independent of the temporal position of the uncorrelated noise. The relationship of the current findings to those for the discriminability of diotic noise stimuli will be discussed. [Work supported by AFOSR.]
Steady-state and transient waves in random composites
Authors: Beltzer Abraham I.
Published: October 2005

A causal approach is applied to investigate harmonic waves in random media, which exhibit both scattering and viscoelastic losses. Since this approach allows for evaluation of the effective wavenumber for the entire frequency interval, the transients may then be investigated by the classical Fourier method. A particular example deals with the scattering model by Wu, and the viscoelastic model by Azimi, which find applications in seismology. Numerical results for a transient response of this Wu-Azimi model are presented. The pulse reinforcing and delaying effects of multiple scattering are shown to be interrelated through a causality constaint.
Determination of a string's impulse and step responses by Laplace transformation; relationships to exciting mechanisms
Authors: Terhardt Ernst
Published: October 2005

The excitation of a musical string is intimately dependent on the string's dynamic behavior—i.e., of the string alone—at the point of excitation. With resonable approximation that behavior can essentially be regarded as that of a linear system. An elegant way to describe it is by Laplace transformation. On the basis of the familiar equivalence of string and homogeneous electrical transmission line, the string impedance at the excitation point is expressed in Laplace-transform notation. This serves as a basis for getting the frequency characteristics of the impedance (magnitude and phase), and, by inverse Laplace transformation, the impulse and step responses of force and velocity, respectively. These characteristics of the string alone prove to be very helpful in discussing the interaction between a string and any exciting device such as a bow or piano hammer.
Phonotactic constraints as a filter of the articulatory-acoustic signal
Authors: Solé Maria-Josep
Published: October 2005

The present study investigates the working and status of phonotactic constraints in the modeling of speech production and speech perception. Phonotactic constraints act as a filter of the acoustic signal and the subsequent articulatory gestures. The adaptation of foreign borrowings and foreign language learning provide many examples of the transfer of the phonotactic constraints of L 1 to the perception and production of L 2, e.g., English speakers' pronunciation [“nou” sei] for the Spanish sequence [“no”se] “I don't know,” and [ɛl ei “trei⃗” bɛl] for the French sequence [ɛl ɛ “trɛ” bɛl] “she is very beautiful,” shows how the English syllable structure constraint that prevents short vowels from occurring in stressed open syllables is imposed on these languages. When this syllable structure constraint is not present, though, as in the words [ɛl] “elle,” [bɛl] “belle,” English speakers pronounce a short vowel. To check whether higher-order phonotactic constraints act as a filter of the acoustic signal, the same physical signals were placed in different syllabic structures by digital manipulation with an ILS program. The stimuli were presented to speakers of different languages to check whether they perceived the same stimuli differently depending on the phonotactic constraints of their language. The results show that phonetic and phonological identification is overridden by phonotactic constraints, which advocates for a top-down processing of the signal.