bluuebunny/crossref_metadata_2025 huggingface dataset:
Sampling requirements for nth-order correlations
Authors: Pflug Lisa A. , Ioup George E. , Ioup Juliette W.
Published: October 2005

As has been derived previously [Pflug, MS thesis, Univ. of New Orleans (1990); Pflug et al., J. Acoust. Soc. Am. 91, 975–988 (1992); Pflug et al., J. Acoust. Soc. Am. 94, 2159–2172 (1993)], the sampling intervals required to prevent nonremovable and removable aliasing in higher-order correlations calculated from discrete-time data are Δt3≤1/(3ft) for the bicorrelation and Δt4≤1/(4ft) for the tricorrelation, where ft is the highest or top frequency present in a signal. It is shown here that a general expression for the sampling required to prevent aliasing for each order n of correlation calculated from discrete-time data is Δtn≤1/(nft). Time-domain computer calculations of correlation central ordinate values for orders two through eight are consistent with this result. Removable aliasing can be eliminated for data which are sampled such that Δt≤1/(2 ft) by (1) the application of n-dimensional transform or time-domain masking filters, (2) one-dimensional filtering of the transform domain diagonal factor, or (3) interpolation of the data before correlating.
Acoustic and perceptual properties of intervocalic consonants produced by talkers with cerebral palsy
Authors: Bunnell H. Timothy , Hoskins Steven , Polikoff James
Published: October 2005

Speech produced by ten talkers with cerebral palsy was studied. Talkers recorded semantically anomalous sentences of the form ‘‘The N1 is Ving the N2’’ where N1, N2, and V are single-syllable nouns and verbs (in the bisyllabic infinitive form) selected from lists of noun and verb target words. Listeners heard sentences over headphones and identified the target words in a closed response set task in which each target word had an associated set of four to six minimally different response alternatives (e.g., {boat, moat, vote, oat}). For the present analyses, only verb targets that differed in the final consonant of the root word (e.g., waiting, wading, waning, waving, weighing) have been examined. Perceptual data were analyzed for percentage of incorrect responses and proportions of various types of errors (e.g., voicing/place/manner) per token. Acoustic analyses included measures of vowel and consonant durations, extent of VC and CV formant transitions, categorical measures of a variety of acoustic features such as presence/absence of voicing in the consonant constriction interval, nasalization, and laryngealization. Analyses completed on six of the ten talkers’ data suggest that inappropriate presence/absence of voicing and laryngelization, and restricted F1 VC (but not CV) transitions are most predictive of perceptual errors. [Work supported by the Nemours Foundation.]
Perception of processed speech by the profoundly hearing impaired
Authors: Bosman Arjan J. , Smoorenburg Guido F.
Published: October 2005

For many profoundly hearing-impaired speech reading is the most important means of communication; amplified speech may provide, at best, additional information to speech reading. In an attempt to improve audio-visual communication, speech pattern elements that were thought to be most beneficial as a supplement to lip-reading were analyzed. The elements were fundamental frequency (f0), voicing, and the first two formants (F1 and F2). With these elements auditory stimuli were pro-duced with different encodings for voiced speech fragments. In the F1F2 encoding both formants were represented by two adjacent harmonics of f0 around each formant frequency; in the F1 encoding by two harmonics of f0 around F1. In the f0 encoding fundamental frequency was encoded as a single sine wave. In all cases white noise was used during voiceless speech. Out of 20 profoundly hearing-impaired subjects, all subjects but one showed a considerable improvement in lipreading scores when supplemented with an auditory stimulus. In most cases highest scores were obtained with the natural speech condition. For four subjects the F1-encoded signal provided highest scores. Relations among intelligibility scores and dynamic range, gap detection, and difference limen for frequency will be discussed.
Reassessment of the role of head movements in human sound localization
Authors: Wightman Frederic , Kistler Doris , Andersen Kristen
Published: October 2005

This project sought to quantify both the nature and consequences of a listener’s head movements during a sound localization task. The task required listeners to report the apparent direction and distance of virtual sound sources. The virtual source stimuli were synthesized from measurements of each listener’s own head-related transfer functions and were presented over headphones so that the acoustical consequences of head movements could be controlled. In one condition head movements were discouraged, and the stimuli delivered to the headphones were not influenced by movements of the listener’s head. In another condition the listener was encouraged to use small head movements to aid localization. The position of the listener’s head was tracked and the synthesis of each virtual source was modified in real time, in accordance with the head movements, to simulate a stationary external source. For those listeners who demonstrated a high rate of front–back confusions in the first condition, head movements apparently provided the information needed to resolve those confusions, since the confusion rate was near zero in the second condition. There was also some improvement in elevation perception with head movement information provided. Analyses of the head movement trajectories support the hypothesis that the major role of head movements is resolution of the confusions that result from reliance on interaural time and intensity cues. [Work supported by NIH, NASA, and the ONR.]
Multimicrophone hearing aids with binaural output
Authors: Desloge Joseph G. , Zurek Patrick M. , Rabinowitz William M.
Published: October 2005

Multimicrophone hearing aids, implemented with fixed (time-invariant) filters, can enhance hearing aid sensitivity in a target direction (e.g., straight ahead) relative to other directions. Most designs, however, produce a monaural output, resulting in the loss of interaural signal differences that provide a sense of space. This paper explores single- and dual-array binaural output hearing aids designed to achieve a compromise between directionality and the fidelity of interaural time differences (ITDs). Single-array systems use one broadside array to form both output signals; microphone weights are selected to maximize the directional sensitivity for each output signal, subject to a constraint on the error between the system’s output ITDs and the ‘‘true’’ ITDs. A special case of these systems exploits the facts that low-frequency ITDs dominate sound localization and that broadside arrays achieve significant directionality only at high frequencies. In this case, the microphone weights retain ‘‘true’’ ITDs at low frequencies and maximize directionality at high frequencies. Dual-array systems use two independent endfire arrays to generate the two output signals; microphone weights are selected to maximize directionality for each array separately, and the physical spacing between the arrays produces the ITDs between the two output signals. [Work supported by NIDCD.]
Array shading for matched-field processing
Authors: Livingston Ellen , Porter Michael B.
Published: October 2005

Matched-field processing (MFP) is a direct generalization of plane-wave beamforming to correct sonar systems for the effects of refraction in the ocean. However, operational sonar systems never use a simple plane-wave source. As is well known, the array should be shaded or tapered to reduce sidelobes. This same principle is valid for MFP; however, shading reduces only a subset of the MFP sidelobes. How to do the shading and when it is beneficial will be discussed.
The effects of accent and target predictability on perception of mispronunciations
Authors: Schmid Peggy M. , Yeni-Komshian Grace H.
Published: October 2005

This study makes use of a listening for mispronunciations (LM) task utilizing English sentences produced by native and nonnative speakers. The test sentences included high (H) and low (L) predictability target words containing mispronunciations (MPs) that were constructed by changing the initial segmental phoneme in the target words along the dimensions of voicing, place, and manner. Sentences not containing MPs were judged by native listeners for overall accent and the speakers were classified as native, having a mild-to-moderate accent or having a heavy accent. Another group of native listeners were presented the LM task. The results showed that the listeners were faster and more accurate in detecting MPs produced by the native than non-native speakers. They were more accurate, but not faster, in detecting MPs produced by non-native speakers with milder accents, as compared to heavier accents. The results also indicate that the listeners were faster and/or more accurate n detecting MP in the H sentences, and this was more pronounced with the sentences produced by the non-native speakers. The findings suggest that listeners are less accurate in detecting mispronunciations produced by non-native speakers and that the accuracy of their responses decreases as the degree of accent increases.
Temporal characterization of flat-spectra natural acoustic transients
Authors: Grasso Frank , Mountain David C.
Published: October 2005

Certain natural acoustic transients produce broad and relatively featureless spectra. Spectrographic analysis has revealed that rustling leaves, breaking sticks, and flowing water, which are likely to have shaped the evolution of the mammalian auditory system, are examples of this class of transients. Both types of signals are composed of the superposition of smaller transients, but breaking sticks produce short duration components which are separated by brief silences while the rustle of leaves and flowing water consist of frequent, overlapping components. These differences in the temporal characteristics form a perceptual basis for the discrimination of these signals. It is found that these transients are easily classified by human listeners provided that a sample of adequate length is given. The results imply that classification of these acoustic transients must be based on temporal features instead of spectral features. A second implication is that the spectrum of the signal at the tympanic membrane will be shaped more by filtering due to the path of propagation from the source to the listener than the nature of the acoustic source. [Research supported by ONR.]
Tonal word accent II in Swedish speech directed to infants
Authors: Sundberg Ulla
Published: October 2005

Motherese (or child-directed speech) denotes a special speech style typically used by mothers and other caretakers in their interaction with infants. Prosodic modifications at sentence or phrase levels—such as higher mean fundamental frequency, wider pitch excursions, tonally and temporally coherent intonation contours—have been observed in a number of studies [e.g., Fernald and Simon, Dev. Psychol. 20, 104–113 (1984)]. Such modifications are also likely to affect the intonation contour in the word domain. This paper reports an investigation of tonal and temporal aspects in disyllabic accent II words, produced by Swedish mothers in spontaneous interaction with their 3-months-old infants. The child-directed speech data are contrasted with matching adult-directed speech data. Preliminary results are compatible with those from earlier studies. The results suggest that work emphasis is signaled differentially in infant-directed speech and adult-directed speech. Much wider pitch excursions were observed in the accent II words occurring in the former than in the latter case. In infant-directed speech, F0 may be the primary variable for marking prominence while in adult-directed speech duration seems to be the corresponding one [Sundberg, PERILUS XVII, 65–74 (1993)].
The asymmetric structure of the infant’s perceptual vowel space
Authors: Lacerda Francisco
Published: October 2005

This paper reports a study of the infant’s perceptual sensitivity to F1 and F2 changes occurring in the central region of an adult male’s vowel space. The data were collected from a group of 16 Swedish infants whose ages varied from 6 to 12 months. The infants were tested with the headturn procedure in their ability to discriminate variants of a reference schwa vowel. Four variants were generated by introducing a fixed increment or decrement (in Bark) along either F1 or F2. The results are compatible with previously reported data obtained for vowel contrasts in the low/back region of the vowel space [F. Lacerda, J. Acoust. Soc. Am. 93, 2372(A) (1993)]. Thus the general notion that there is a perceptual asymmetry favoring F1 differences during the early stages of vowel perception is supported by the present results. The paper attempts to argue that the early structure of the infant’s vowel space might be influenced by the combined effects of both the perceptual dominance of F1 contrasts and the infant’s larger articulatory precision along the open/close than along the front/back dimension. [Research supported by The Bank of Sweden Tercentenary Foundation, Grant 90-0150.]
Development of infants’ expression and perception of emotion through vocalization
Authors: Shimura Yoko , Imaizumi Satoshi
Published: October 2005

Voice samples produced by six infants at 6, 9, 12, and 17 months of age were perceptually evaluated by 79 adults (aged 20–22) and 31 children (aged 2–6) using 9-point-rating dipole scales representing emotions. The following results were obtained. (1) Both the adult and child listeners perceived rich contents of emotions from the voice samples recorded even at 6 month of age. (2) More factors were extracted from the rating scores given by the children than by the adults via factor analyses, though many characteristics of the extracted factors were common between the two listener groups. These results indicate the following. (1) Even 6-month-old infants who have not yet developed a language can produce voice necessary for emotional communication through nonlinguistic elements of voice. (2) Children are more sensitive in perception of emotions from infants’ vocalization than the adults. Children seem to perceive richer emotions from infants’ vocalizations than the adults.
Infants’ perception of word boundaries in fluent speech
Authors: Jusczyk Peter W. , Myers James T. , Charles-Luce Jan
Published: October 2005

The present study investigates infants’ sensitivity to word boundaries in fluent speech contexts. Using the headturn preference procedure, the first experiment demonstrated that 101/2-month-old American infants listened significantly longer to passages in which artificial 1-s pauses were inserted at word boundaries, as opposed to between syllables within words. A second experiment examined the possibility that word-stress patterns affect infants’ sensitivity to word boundaries in fluent speech. New groups of 101/2-month-olds were tested on new sets of passages. One group received passages with pauses at word boundaries or within words for words having a strong-weak (SW) stress pattern. Another group received similarly arranged passages but the pauses involved words having a weak-strong (WS) pattern. If infants use the onsets of strong syllables as cues to word onsets, they might be expected to prefer between-word pauses in the SW passages but within-word pauses in the WS passages, In fact, in both cases infants listened significantly longer to passages with between-word pauses. These results suggest that infants at this age may not rely heavily on word-stress patterns in locating word boundaries in fluent speech. [Work supported by NICHD and NIDCD.]
Experimental study of the scattered near field of submerged objects with surface impedance discontinuties
Authors: Martin James S. , Rogers Peter H.
Published: October 2005

The extreme near field of several targets that incorporated abrupt surface impedance discontinuities was measured in the frequency range of 5 to 40 kHz using a medical ultrasound probe as a miniature hydrophone. The probe was mounted in an automated positioning system designed specifically for this application. Although it incorporated a relatively insensitive hydrophone and a weak source, the measurement system exhibited adequate dynamic range (on the order of 80 dB) for this experiment. Targets were acoustically large with ka in the range of 1 to 10 in the measurement frequency range. Insonifying signals were narrow band and virtually plane wave. Cylindrical, spherical, and planar targets were studied. Measurements were made of total surface pressure and pressure gradient on both uniform and mixed boundary objects. High wave-number standing waves were observed in the region of the discontinuities. Good agreement with both three-dimensional boundary element and two-dimensional collocation theory was observed at the low end of the frequency range. Issues of hardware design, signal processing, hydrophone–surface separation, accuracy of positioning, and spatial resolution will be discussed in addition to a qualitative analysis of data in the light of previous modeling efforts. [Work supported by ONR.]
Self-consistent scattering theory for normal mode propagation
Authors: Tracey Brian H. , Schmidt Henrik
Published: October 2005

Rough surface scattering in ocean waveguides causes a loss of signal coherence and transfers energy between the guided modes of the waveguide. These effects are important for prediction and signal processing applications, and have been studied using techniques such as coupled mode theory. As an alternate approach, a self-consistent perturbational scattering theory developed by Kuperman and Schmidt [W. A. Kuperman and H. Schmidt, J. Acoust. Soc. Am. 57, 1511–1522 (1989)] is rewritten in terms of a normal mode representation of the pressure field. This approach is significantly less computationally intensive than the wave-number integration formulation used previously. The decay of the coherent field and statistics of the scattered field such as the cross-modal coherences can be calculated. The approach allows an arbitrary number of layers separated by rough interfaces and can be extended to elastic media as well. Numerical results are presented for a realistic shallow-water ocean environment. [Work supported by ONR.]
Inclusion of rough surface scattering in a finite element parabolic equation propagation model
Authors: Norton Guy V. , Novarini Jorge C. , Keiffer Richard S.
Published: October 2005

Propagation models in underwater acoustics usually incorporate surface scattering effects in an ad-hoc manner that in most cases requires making severe approximations. In particular, to include surface scattering in a marching algorithm for sound propagation in a coherent manner posses a difficult problem. Dozier [J. Acoust. Soc. Am. 75, 1415–1432 (1984)] introduced a novel and rigorous approach to include surface scattering in the framework of the split-step parabolic equation method. In this work the technique developed by Dozier is adapted and implemented in the realm of the finite element parabolic equation (FEPE) acoustic propagation model developed by Collins [J. Acoust. Soc. Am. 86, 1097 (1989)]. The technique is tested by applying it to scattering from a sinusoidal patch as well as from a rough surface patch defined by a Pierson–Moskowitz spectrum. These results are compared against highly accurate solutions to the surface scattering integral equation (method of moments). [Work supported by ONR.]
Improved empirical descriptions of the dependence of surface backscatter on air-sea environmental descriptors
Authors: Nicholas Michael , Ogden Peter M. , Erskine Fred T.
Published: October 2005

Between August 1988 and March 1992 six at-sea experiments were performed in which sea surface backscattering strengths were measured from ∼70 to ∼1000 Hz utilizing explosive (SUS) charges. (These were part of the Critical Sea Tests.) The latter of the six experiments (CST-7) was particularly interesting in that wind speeds as high as 17.5 m/s (at 10-m height) were encountered, which is 4 m/s higher than in any of the earlier experiments. Here, results obtained from CST-7 will be compared with those from the five earlier tests, and some important differences will be presented. Some new empirical formulas will be presented that describe the results from all six of the CST tests better than the Ogden–Erskine algorithm. (The Ogden–Erskine algorithm was formulated using data from the first five tests only and is now widely regarded as a much better description than the older Chapman–Harris formula.) Possibilities for improving still further the prediction of surface scattering strengths will be discussed. [Work supported by ONR.]
Anomalous frequency behavior in low-frequency sea-surface backscatter
Authors: Ogden Peter M. , Erskine Fred T. , Nicholas Michael
Published: October 2005

Surface backscattering strengths have been measured between 70 and 1500 Hz using broadband SUS charges as sources in the Critical Sea Test 7 at-sea test. While the results of the measurements for frequencies of 1 kHz and below have been presented previously, the extension of the results up to 1.5 kHz have shown some unexpected frequency behavior in the scattering strengths as a function of wind speed. For wind speeds of 15 m/s and higher, scattering strengths at a fixed grazing angle are found to peak in the 600- to 1000-Hz region and then decline with increasing frequency, while for lower wind speeds the scattering strengths increase roughly monotonically with increasing frequency. Possible explanations for this behavior will be discussed. [Work supported by ONR.]
Low-frequency acoustic wave generation in a resonant bubble layer
Authors: Druzhinin O. , Ostrovsky L. , Prosperetti A.
Published: October 2005

The enhancement of frequency transformation of acoustic waves (in particular, in parametric arrays) by bubbles added to water has been discussed for about a decade. However, the resonance losses usually degrade the efficiency of the process. Here, the possibility of using small, nonresonant bubbles is considered and the effect by exploiting the resonance of the whole bubble layer is enhanced. It is assumed that a plane wave is incident on such a layer and the transmitted and reflected fields, including the low-frequency waves are investigated, both analytically and numerically. For bubble volume fractions β≊10−3, at a frequency ratio of about 10 and for pump amplitudes of the order of 10−1 atm, the power of the low-frequency signal (including waves radiated in both the directions) may reach 10% of the total power of the incident biharmonic wave. This is a very good efficiency for processes of this type. Further improvements are difficult due to the formation of shocks. [Work supported by the Science Opportunities and Ocean Acoustics Programs of ONR.] a)Permanent address: Inst. of Appl. Phys., Russian Acad. of Sci., Nizhny Novgorod, Russia.
Single surface integral equation for penetrable wedge scattering
Authors: Davis Anthony M. J. , Scharstein Robert W.
Published: October 2005

The transmission problem of time-harmonic acoustic scattering by the velocity/density contrast wedge is formulated, through symmetry arguments and with the construction of suitable Green’s functions, as a pair of uncoupled surface integral equations, each with one unknown function defined on a single wedge face. The convergent solution to the Fredholm integral equation of the first kind is expressed as a Galerkin series of Laguerre polynomials, and the development takes account of the distant behavior anticipated from the asymptotic solution to the related Sommerfeld half-space problem. The required inner products for the Galerkin projection scheme, which are integrals of products of the weighted Laguerre polynomials and the pair of Green’s functions for the separate homogeneous regions, are written as Taylor series coefficients of an auxiliary function. Efficient numerical implementation of the physically based analysis produces an accurate and intuitive picture of the wave interactions with this canonical scatterer. [Work supported by the Naval Research Laboratory, Stennis Space Center.]
Zooplankton target strength: Areal or volumetric dependence?
Authors: Demer David A. , Martin Linda V.
Published: October 2005

Targets strengths of various zooplankton were measured at 200, 420, and 1 MHz and the dependence of these data on animal cross-sectional area versus volume was explored. The 420- and 1-MHz data were collected with a dual-beam sonar system and the 200-kHz data with a split-beam system. Experiments were conducted with live, but tethered, individuals in an enclosure filled with filtered seawater. The data were compared to both empirical and theoretical models of reduced target strength (RTS) versus ka (the product of wave number and equivalent cylindrical or spherical radius). Theoretical models chosen for this comparison were a volumetrically dependent high-pass bent-cylinder model and an areally dependent ray bent-cylinder model. Goodness-of-fit to these models was evaluated. The dependence of acoustic backscattering on animal volume or area was tested by fitting regression lines for TS vs ka, length, wet weight, and dry weight. The practical accuracy of each of these models was then evaluated in a demonstration of a multi-frequency inversion technique for animal size classification. [Work supported by the Hertz Foundation.]
Speech-based measures of hearing aid processing
Authors: Kheirallah Issam , Schneider Todd , Jamieson Donald G.
Published: October 2005

The electroacoustic properties of many modern hearing aids change as a function of the input stimuli. One consequence is that electroacoustic measurements obtained using commercial hearing aid test systems may differ from those made with important, ‘‘real-life’’ signals. As speech is the most important real-life signal for most hearing aid users, tests using speech stimuli have been proposed. This paper describes one approach to such testing, using spectrograms to display speech signals in a three-dimensional representation. Dual spectrogram displays prepared using the computerized speech research environment (CSRE) software allow speech signals at the input and output of a hearing aid to be compared. Such spectrograms are computed for a set of important phonemes extracted from running speech. The results of these analyses are evaluated for individual hearing aid users using a display which includes the user’s thresholds and loudness discomfort levels (LDLs), together with the target amplification levels specified by the individual’s hearing aid prescription. Such displays provide concise representations of the audibility of aided speech tokens for particular individuals. The effects of time-varying processing are addressed with additional tests which measure how specific, putative speech cues are affected by hearing aid processing. [Work supported by grants from NSERC and OMH to D. G. Jamieson.]
Neurophysiologic bases of pitch and place of articulation perception: A case study
Authors: Sharma A. , Kraus N. , Carrell T. , Thompson C.
Published: October 2005

Behavioral and neurophysiologic correlates of pitch and phoneme perception were investigated in a 42-year-old male with a unilateral cortical lesion (due to left hemisphere frontal-temporal-parietal craniotomy). Functional impairment of his speech perception ability was reflected in his behavioral performance. Electrophysiologic measures (ABR, MLR, MMN) were used to assess the underlying neurophysiologic processes. In the behavioral experiment the stimuli were synthesized syllables differing in place of articulation (/da/, /ga/) and pitch (high, low). The pitch and place differences were equally discriminable. A same-different behavioral discrimination task revealed that the subjects discrimination of pitch was intact, however his discrimination of place was severly impaired. The mismatch negativity (MMN) auditory-evoked potential is a pre-attentive neurophysiologic index of acoustic change. Of interest was whether the MMN would reflect the selective impairment in phonetic perception at a pre-attentive level. Results revealed that the MMN was elicited by pitch differences in speech stimuli but not by place differences (i.e., consistent with behavioral discrimination). Thus the MMN appears to reflect the distinct neuroanatomic sites that underlie processing of different auditory stimulus attributes. Theoretical implications for neurophysiologic processes underlying pitch and place of articulation perception will be discussed.
Vowel spaces in the speech of profoundly hearing impaired children
Authors: Tobey Emily A. , Fourakis Marios , Geers Ann E.
Published: October 2005

Centralized vowels, reflected in a reduced vowel space, are commonly associated with the speech of profoundly hearing impaired speakers. In order to characterize longitudinally the vowel spaces of children with profound hearing impairments, recordings of 12 children were obtained at two time periods separated by 3 years. Five repetitions of the vowels, /i/, /i/, /eh/, /u/, and /open oh/ produced in hVd context were recorded and digitized. Measurements were made of the first three formant peaks and fundamental frequency at the first 50-ms steady-state period of the vowels. The means for each vowel were plotted and the total space defined by the means was computed for each child at each recording date. Initial results for half the children indicated reduced vowel spaces in the initial recording session and increases in the size and changes in the shape of the spaces at the last session. Data from the remaining children will be presented and discussed relative to the effectiveness of using vowel spaces to evaluate vowel production by profoundly hearing impaired children. [Work supported by NIH.]
Voice onset time contrasts in the speech of profoundly hearing impaired children
Authors: Fourakis Marios , Geers Ann E. , Tobey Emily A.
Published: October 2005

Children with profound hearing impairments typically err in the production of the voiced voiceless contrast in stops. In order to examine how speech training and experience with various types of prosthetic devices influences these contrasts, four groups of children were recorded producing words beginning with voiced and voiceless stops. Each group was comprised of a conventional hearing aid subject, a tactile aid subject, and a cochlear implant subject. Recordings were made before the children were fitted with either the tactile aid or cochlear implant and 2 years later. Measurements of voice onset time (VOT) were made from the waveforms. Preliminary results from one group of children revealed the voiced and voiceless distinction was correctly produced for bilabial and alveolar stops at both dates. For the velar stops, no child produced a VOT contrast at the first recording date. The child fitted with a cochlear implant produced longer VOTs for voiced velar stops than for voiceless ones. After 2 years experience with the devices, all children demonstrated normal VOT contrasts for velar stops. Data from the remaining three groups will be presented and discussed relative to prosthetic device and experience with the devices. [Work supported by the NIH.]
Speech production before and after deafening
Authors: Manzella Joyce , Wozniak Jane , Matthies Melanie , Lane Harlan , Guiod Peter , Perkell Joseph
Published: October 2005

The role of hearing in speech production was investigated by analyzing the speech of an adult female before and after she experienced sudden, substantial hearing loss. Prior to the onset of this loss, she had a mild-to-moderate hearing loss in one ear (aided), and was deaf in the other due to bilateral acoustic neuromas. She became deaf bilaterally when the second of these neuromas was surgically removed. Following this surgery, an auditory brainstem implant provided minimal speech reception benefit. Three speech production recordings made prior to deafening were compared to recordings made 11 and 35 weeks post-deafening. Results indicated significant changes in voice onset time (VOT), fundamental frequency (F0), F0 range, and vowel duration. VOTs, adjusted for changes in syllable duration [Lane etal., J. Acoust. Soc. Am. (to be published)], were significantly shorter for the voiceless plosives post-deafening. F0 was at the mean of a normative range [Holmberg etal., J. Voice 3, 294–305 (1989)] prior to deafening, and rose significantly above this range post-deafening. An analysis of prosody indicated that the subject placed pitch accents on the same syllables post-deafening, but F0 mean and s.d. were significantly higher. Vowel formants, /s–sh/ contrast, an indirect measure of breathiness, and overall SPL, showed no significant changes by 35 weeks post-deafening. [Work supported by NIDCD.]
An acoustic study of intonation in one aphasic patient
Authors: Munson Benjamin R.
Published: October 2005

An acoustic study of patterns of intonation and phrase-final lengthening was completed for one aphasic patient, referred to as Nick. Nick, who is technically classified as a Broca’s aphasic with a large left hemisphere lesion, exhibits an exceptional pattern of language breakdown in that his segmental output has been reduced to the syllable [thopen oh̃]. The results of this study show that the range of Nick’s fundamental frequency is within normal range, while his patterns of phrase-final lengthening are abnormal. This finding is interpreted within the framework of current theory on prosody, which claims that intonation is composed of two distinct components: Prosodic structure (which conditions phrase-final lengthening) and tonal melody [J. Pierrehumbert and M. Beckman, Phonology 3 (1986)]. Nick’s abnormal patterns of phrase-final lengthening are indicative of a breakdown in the prosodic structure component of intonation, while his intact fundamental frequency range illustrates an intact tonal melody component. Nick’s selective impairment of prosodic structure provides further evidence that the two components of intonation are processed by different mechanisms, a claim suggested in previous work [D. Van Lancker and J. Sidtis, J. Speech Hear. Res. 35, 936–970 (1992)]. [Work supported by NIH.]
Vocal development in 6- to 15-month-old children at risk and not at risk to stutter
Authors: Fosnot Susan Meyers
Published: October 2005

Systematic recordings were made at regular intervals (6, 9, 12, and 15 months) and utterances were transcribed and analyzed from speech samples of children at risk and not at risk to stutter. Children were audio and video recorded interacting with their own mother for 10-min play periods. The purpose of the study was to gather quantitative information on fluency development prior to the diagnosis of a stuttering disorder to determine whether or not children can be differentiated based on vocal development. Wideband spectrograms and formant tracking displays were used to analyze oral development (plotting first and second formant frequencies of the steady-state part of the vowel) and the other measurement pertained to laryngeal-oral coordination (analyzing voice onset time in stop consonants). Acoustic analyses were performed using the Kay Elemetrics CSL workstation. Control subjects had more elaborated vowel systems than children who end up stuttering in their vocalizations. Pre-stuttering children also displayed repetitive disfluencies in their vocal play. [Work supported by NIH and ASHF.]
Lingua-palatal coarticulation by deaf and normal-hearing speakers
Authors: Mahshie James J. , Goffen Robin
Published: October 2005

Recent research suggests that deaf speakers often exhibit context-dependent changes in speech articulation [for example, Mahshie etal., ASHA 32 (10), 183 (1990)]. However the coarticulatory patterns of deaf speakers are not always comparable to those of normal-hearing speakers. Furthermore, it is likely that deaf individuals exhibit differences among themselves in both the nature and extent of coarticulation–differences that may affect intelligibility. The purpose of the present study was to examine and compare lingua-palatal coarticulation evidenced by normal-hearing speakers and by deaf speakers differing in overall speech intelligibility. Three normal-hearing subjects, one intelligible deaf subject, and one semi-intelligible deaf subject produced multiple iterations of bisyllabic and trisyllabic words. Test words contained the lingua-alveolar target segments /t/ or /n/ followed by either the neutral vowel /schwa/ (e.g., ‘‘tana’’) or the velar consonant /k/ (e.g., ‘‘tancat’’). Palatometric measures were used to compare lingua-palatal contact patterns during production of the target consonants in the vowel and consonant contexts. Results showed that the intelligible deaf speaker, like the three normal-hearing subjects, exhibited context-dependent changes in articulation of the target segments, while the semi-intelligible deaf subject showed little evidence of anticipatory coarticulation. Possible motor organization strategies employed by the deaf subjects will be discussed.
Vowel training experiments with a computer-based vowel training system
Authors: Zahorian Stephen A. , Correal Neiyer S.
Published: October 2005

In previous work signal processing algorithms were presented for real-time mapping of vowels to a two-dimensional display for articulation training [Beck and Zahorian, ICASSP-92, II, 241–244]. In this paper, a series of tests designed to evaluate the effectiveness of this display for vowel training are reported. Experiments were conducted with five non-native normally hearing speakers of English and with four hearing-impaired children. The foreign speakers practiced with the vowel training aid for two 30 min sessions per week over a 10 week period. Pre, mid, and post-training testing showed that all subjects learned to modify vowel productions to consistently match the specified ‘‘target’’ vowel positions depicted on the computer. The vowel training exercises with hearing-impaired school children (ages 7 to 10) were performed in therapy sessions over a 1-year period. The quantitative evaluation of the children’s data is more ambiguous than for the foreign-speaker training, but there was some progress. These results show that the instantaneous visual feedback provided by the vowel training system can be used to improve vowel productions, but that additional improvement is still required to make the system more effective for hearing-impaired children.
Correlation of familiarity ratings between auditorily and visually presented Japanese words
Authors: Amano Shigeaki , Kondo Tadahisa , Kakehi Kazuhiko
Published: October 2005

Word-familiarity databases have usually been developed for visually presented words, not for auditorily presented words. The purpose of this study is to develop a familiarity database for both auditorily and visually presented words, and to investigate the relationship between both representations. Using a 7-point scale, ten Japanese adults rated the familiarity of every word in the Shinmeikai Japanese dictionary (Tokyo: Sansei-do, 1974)—about 62 000 words. The words were auditorily presented to each subject in one session and visually presented in another. The Pearson correlation coefficient between the auditorily and visually presented words was 0.76 when the mean rating of each word was calculated over the ten subjects. The results show that for a large part, familiarity is basically the same whether a word is presented auditorily or visually. However, a significant number of words received quite different familiarity ratings, suggesting that the auditory mental lexicon and the visual mental lexicon are organized differently to some extent. These differences, at least in part, could be attributed to the idiosyncratic properties of Japanese orthography. The experiment will be continued using more subjects to obtain more reliable databases.
Perceiving juncture visually
Authors: Lin Hwei-Bing
Published: October 2005

It has been shown that lipreaders can distinguish between word pairs such as ‘‘perFECT’’ and ‘‘PERfect.’’ An experimental evaluation of synthetic worked pairs showed that mouth opening and segmental duration are important cues [Levitt, Lin, and Lin (in preparation)]. A phonetic contrast that depends heavily on subtle changes in segmental duration is that of juncture. It was of interest to determine whether word pairs such as ‘‘ill eagle’’ vs ‘‘illegal’’ or ‘‘a name’’ vs ‘‘an aim’’ are visually distinguishable. Two versions of each contrast pair spoken by a male speaker with normal vocal effort were recorded for a set of 67 pairs. The recordings were lipread by eight subjects. Results showed that most of the contrasts were distinguishable. Correct responses were quite consistent between two recordings. Accuracy of the responses was affected by consonant type: both pre-juncture and post-juncture. Further, judgments were found to be biased by frequency of occurrence and linguistic factors. [Work supported by NIDCD.]
Measurement of evanescent waves on a cylindrical shell
Authors: Kil H.-G. , Jarzynski J. , Berthelot Y. H.
Published: October 2005

Calculations are made of the reflection coefficient matrix at the end of a cylindrical shell for various end boundary conditions. The calculations show mode conversion on reflection at the end of the shell, including conversion from propagating to evanescent waves. The evanescent waves are studied experimentally using the laser Doppler vibrometer (LDV) described previously [H.-G. Kil etal., J. Acoust. Soc. Am. 93, 2389(A) (1993)]. The LDV system is used to measure the amplitude and phase of the particle velocity at a large number of points on the shell surface. The data are analyzed in the frequency-wave number domain using Prony decomposition. Data will be presented for a shell 0.94 m long and 1.6 mm thick, freely suspended in air and excited radially by a shaker at approximately twice the ring frequency. [Work supported by ONR.]
Structural response of a machinery noise enclosure
Authors: Martini Kyle , Cole John E.
Published: October 2005

Enclosures are used to control the noise radiated by industrial machines such as pumps and internal combustion engines. The passive transmission loss of enclosures at low frequency can yield negative insertion loss occurring at resonances of the enclosure panels backed by the internal air cavity. Active noise control provides a means to enhance low frequency performance by eliminating enclosure resonances. Because it is not feasible to use far-field acoustic measurements for control, the surface vibrational response of the enclosure is used to control the noise radiated. Enclosure response characteristics are obtained from a finite element model of the three-dimensional enclosure. A vibrated surface within the enclosure is used to represent a machine. When coupled with a boundary element formulation of the Helmholtz integral equation, the model calculates the surface response of the enclosure as well as the far-field radiated pressure. Transfer functions between the excitation and both surface and far-field responses are obtained. Results of the finite element model are compared with analytical models of enclosure performance. [Work supported by the National Science Foundation.]
The variational piezoelectromagnetic equations for elastic dielectrics
Authors: Dökmeci M. C. , Aşkar G. A.
Published: October 2005

The aim of this paper is to extend the variational principles of piezoelectricity [M. C. Dökmeci, IEEE Trans. Ultrason. Ferroelec. Freq. Control UFFC-35(6), 775–787 (1988)] so as to incorporate the magnetic effects. The principle of virtual work is applied to the motions of piezoelectromagnetic medium, and an associated variational principle is derived that yields some of the fundamental equations of the medium and includes its remaining equations as constraints. By use of Lagrange multipliers, the constraints are incorporated into the variational principle and a unified variational principle is derived. Likewise, a variational principle is formulated for an electromagnetic medium with an internal surface of discontinuity. These integral and differential types of variational principles provide a standard basis for generating approximate direct solutions as well as deducing systematically lower order equations of piezoelectromagnetic medium. Also, special cases and the reciprocals of the variational principles are indicated. The results are shown to agree with the earlier variational principles [e.g., M. C. Dökmeci, J. Math. Phys. 19, 109–126 (1978) and P. C. Y. Lee, J. Appl. Phys. 69, 7470–7473 (1991)]. [Work supported in part by The Scientific and Technical Research Council of Turkey.]
Resonance oscillations of infinite and finite elastic structures with inclusions
Authors: Abramian A. K. , Andreyev V. L. , Indejtchev D. A.
Published: October 2005

It has been found that by the type of a system operator and type of inclusions the discrete spectrum may lie above the cutoff frequency of the continuous spectrum as well as below it. It is shown that the standing modes located in the inclusions region are caused by the trapping modes effect. Necessary and sufficient conditions for low-and high-frequency trapping modes were found. The discrete spectrum shifts to the continuous spectrum axis and initiation of high-frequency trapping modes is accompanied by a phenomenon of traveling waves damping. Special attention is paid at the advance of vibration through hydroelastic systems. Despite this, the problem of the effect of symmetry of a structure on the initiation of high-frequency trapping modes is studied. Some natural frequencies of finite structures are equal to discrete frequencies of the similar infinite structures. A peculiarity of the emergence of these frequencies of the finite structures is that the frequencies are multiples of two (in case of one-dimensional structures).
On the nonlinear waves in a slender rod
Authors: Rybak S. A. , Skrynnikov Yu. I.
Published: October 2005

To describe the propagation of nonlinear longitudinal strain waves in a rod that curves into an arc of radius R use is made of the nonlinear Klein–Gordon equation in the form utt−c2uxx+(c2/R2)u= (β/2ρ)(u2)xx. Here, β and ρ are the nonlinearity parameter and the density of the material, and u is the x derivative (the x axis is directed along the rod) of the longitudinal component of the displacement vector, i.e., the longitudinal strain; c is the velocity of linear longitudinal waves. The steady-state exact solution in the form of solitary wave was found. The wave has two symmetrically located vertical edges. The tails of the wave obtained, i.e., the parts that decay infinitely in either direction, have the same structure as the tails of a Korteweg–de Vries soliton. As in the case of the Korteweg–de Vries soliton, the amplitude A and the width Δ of the wave depend on its velocity. However, a different relation exists between the amplitude and the width: Δ∼A1/2.
Beamlike vibration of cylindrical shell with attached flat plate at both ends
Authors: Kovinskaya Svetlana I.
Published: October 2005

The beamlike vibration of a thin circular cylindrical shell with attached thin flat plates at each end is considered. Two mechanisms of the plates’ influence are considered: First, the plates have no stiffness in their own plane, but have stiffness in the direction transverse to their plane; and second, the plates have stiffness in their own plane, but not in the transverse direction. It is shown that the frequency bands are, to a large extent, influenced by each of the above mechanisms. The equations used for the shell vibration are based on a simplification concerning the neglect of the axial bending moment in the shell. The boundary condition equations (equations of contact) lead to a characteristic equation of beamlike vibration of the shell with attached plates. The resonance frequencies for the shell with the plates are determined by experiment also. The results of the calculation of the resonance frequencies, taking into account the plane displacements of the plates, are close to the frequency determined experimentally.