bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of unexpected tones in noise: The effect of signal duration
Authors: Wright Beverly A. , Dai Huanping
Published: October 2005

The effect of signal duration on the detectability of unexpected tones masked by a continuous wideband noise was assessed using a probe-signal method. This method encourages the listener to attend to a target frequency by presenting the signal most often at that frequency, and only occasionally at other unexpected probe frequencies. The attention contour (percent correct as a function of probe frequency) was considerably broader with 5-ms than with 295-ms signals. However, auditory filter shapes measured using the notched-noise technique were very similar for those two signal durations, indicating that the results obtained in the attention experiments do not simply reflect peripheral frequency selectivity. Further supporting this interpretation, probe tones having the same frequency but a different duration from the target were poorly detected. It is proposed that the subject listens through a time-frequency window whose location and shape in the time-frequency plane is determined by the duration and frequency of the target. [Work supported by the NIDCD and NIH.]
Distribution discrimination of signal duration
Authors: Weber Daniel L. , Sanger Stephen P.
Published: October 2005

This experiment examined a listener’s ability to judge signal duration in the context of a 2IFC, distribution discrimination procedure. A ‘‘standard’’ distribution for the duration of a 1-kHz sinusoid had a mean of 10, 30, 100, 200, or 500 ms. Comparison distributions had means 1.05, 1.1, 1.2, and 1.4 times that of the standard. Both were normal distributions with standard deviations equal to the difference in the means. (All conditions thus yield a d’ of 1.0 for an ideal observer making a single observation. Obtained d’s vary as the separation of the means changes with respect to the duration jnd.) In each observation interval, listeners were presented with 1, 2, 3, 4, 5, 6, 8, 12, or 16 different samples (a fixed number within a block of trials) from one of the two distributions and had to identify which interval was drawn from the comparison (longer mean) distribution. The observed increase in d’ with up to six presentations is well described by the observation-integration model [D. M. Green, J. Acoust. Soc. Am. 30, 904–911 (1958)] in all conditions. Our listeners generally fail to show improvement beyond 8 presentations, so the partitioned-variance model [D. E. Robinson and B. G. Berg (1986)] described by Lutfi [R. A. Lutfi, J. Acoust. Soc. Am. 86, 934–944 (1989)] provides a better fit to the entire set of data. [This research was supported by a grant from AFOSR through WPAFB AL/CFBA.]
Pure-tone thresholds of 1-month-old infants
Authors: Werner Lynne A. , Mancl Lisa Rickard
Published: October 2005

Thresholds for the detection of tones at 0.5, 1, and 4 kHz were estimated for 1-month-old infants using insert earphones. On each trial, the infant was presented with either 8 repetitions of a tone burst or with no sound for an 8-s period.Based on the infant’s response, an observer, blind to trial type, gave a confidence rating at the end of each trial. Correct infant responses were reinforced. The level and frequency of the tone were fixed within a session; several sessions, at different levels, were completed for each subject. The confidence ratings were used to calculate p(A). Performance for a session was taken as the highest p(A) achieved in a block of 8 trials. Thresholds were calculated as the level at which p(A)=0.83, where 0.83 just exceeds chance for 8 trials. Thresholds were calculated for infants who achieved p(A)≥0.83 in at least one session and who had monotonic psychometric functions. The results were in close agreement with previous studies and suggest that 1-month-old infants are more sensitive at lower frequencies. The current procedure uses fewer trials to estimate a threshold and allows thresholds to be estimated for a higher proportion of the infants tested. [Work supported by NIH.]
The internal signal-to-noise ratio in hearing-impaired listeners
Authors: Leek Marjorie R. , Van Summers W. , Cord Mary T.
Published: October 2005

The reduced frequency resolution often demonstrated by listeners with sensorineural hearing impairment might have at least two related effects on their perception of speech in background noise. The internal representation of the peaks and valleys in the speech spectrum become smeared, resulting in less precise frequency analysis than can be achieved by normal-hearing persons. In addition, when the speech is embedded in noise, poorer frequency resolution will, in theory, result in a greater-than-normal decrease in the signal-to-noise ratio at the outputs of the auditory filters. This poorer-than-normal internal S/N might account for the common observation that noise is more degrading to speech understanding by hearing-impaired listeners than by normal-hearing listeners. To assess the validity of this notion, both normal-hearing and hearing-impaired subjects participated in an identification experiment using highly simplified vowel-like harmonic complexes presented in quiet and in three levels of broadband noise. After equating individual performance in terms of percent correct identification in quiet, trading relationships were established between amount of spectral contrast in the stimuli (level differences between peaks and valleys in the spectra) and levels of the background noise. When the effect of spectral smearing introduced by reduced frequency analysis was compensated by increasing the input spectral contrast, the effects of additional background noise were similar for normal-hearing and hearing-impaired groups of subjects. Results from individual listeners will be discussed in light of the degree of impaired frequency resolution as determined by auditory filter shape measurements. [Work supported by NIH.]
Sound localization in noise with hearing protectors: The effect of aging
Authors: Abel Sharon M. , Hay Valerie H. T.
Published: October 2005

Sound localization ability was assessed in two groups of 24 normal-hearing subjects, aged 20–35 and 40–60 years. The test was conducted in a semi-reverberant chamber, using an array of six speakers, surrounding the subject at azimuth angles 60° apart, at a distance of 1 m. Three variables were investigated: the wearing of hearing protectors (unoccluded, conventional E-A-R plug and E-A-R muff, and Bilsom 2392 stereophonic muff with limited amplification), background (quiet vs 65 dB SPL white noise), and stimulus frequency (500 vs 4000 Hz). For each of the 16 listening conditions, one block of 120 trials was presented. Within a block, the test sound, an 80-dB SPL 300-ms one-third octave noise band, was randomly presented from each speaker on 20 trials. The subject judged the direction using a hand-held response box with an array of microswitches configured like the speaker array. Analysis of the overall and conditional proportions of correct response and the correct and incorrect response times is currently underway. Focii of interest are the effects of (1) stereophonic amplification on accuracy and (2) aging on decision reaction time.
Wheel chair vibration and bioresponse criteria
Authors: Collier Robert D.
Published: October 2005

Wheel chairs are being used increasingly in outdoor environments including paved and unpaved roads and sidewalks with widely varying roughness. Wheel chair design and development for active users is a lively field in which weight, stability, control, and comfort are important design criteria. An ongoing research project at Tufts includes baseline laboratory and field vibration measurements of both conventional and new prototype wheel chairs and associated bioresponse. A test track includes a range of roughness conditions. Representative results show: (1) wheel hub vibration levels on the order of 1–3 g (0–200 Hz) with impulse waveforms of 5–10 ms occurring several times a second; (2) frequency response functions of a standard wheel chair structure contain several low-frequency resonances below 100 Hz that are lightly damped; (3) cushions provide comfort but limited low-frequency vibration and shock isolation. A review of models of whole body vibration together with an analysis of wheel chair dynamics provide guidance for vibration isolation/stability design criteria for nonstationary impulsive forces. An isolator that can be installed on an existing chair has been designed and evaluated.
Auditory organization in music: Let the (defunct) composer speak
Authors: Divenyi Pierre L.
Published: October 2005

Auditory organization of music as the stimulus must reflect to a large degree the organization and the structure of ‘‘musical building blocks’’—elements consisting of notes and simultaneous clusters of notes, as well as patterns built from successive elements—intended by the composer. One aspect of this organization is the internal cohesion of successive elements, i.e., the formation of amelodicstructure or an auditorystream [A. S. Bregmann, AuditorySceneAnalysis (MIT, Cambridge, 1991)]. Experimental and theoretical foundations of auditory stream cohesion and stream segregation, developed during the last two decades, make it possible to derive rules that are both solidly anchored in psychoacoustic reality and that, at the same time, are well-integrable with music theory (see the following paper by David Huron in this session). However, much can be learned from observing musical compositions to see how the composer makes the elements come together to form melodic entities, or to break up into separately audible voices (streams). While, for the most part, compositional practice confirms predications of psychoacoustic-auditory stream theory, not infrequently, the results are contrary to expectations and, sometimes, to common sense. Excerpts from pieces throughout Western music history will be shown and demonstrated in an effort to illustrate usual as well as unusual examples of melodic organization. [Work supported by the National Institutes of Health and the Department of Veterans Affairs.]
A derivation of the rules of voice-leading from perceptual principles
Authors: Huron David
Published: October 2005

The tradition rules of voice-leading in Western music are elucidated using empirically established perceptual principles. Six core principles are shown to account for the majority of traditional rules of voice-leading given in music theory texts. The pertinent principles include the principle of dissonant spread, the principle of tonal fusion, the pitch proximity principle, and the pitch comodulation principle. These principles are treated as axioms in a formal system from which the traditional rules of voice-leading are derived. All of the major rules of voice-leading are derived—including such arcane rules as avoiddoublingtheleading-tone, and whenapproachinganoctavebysimilarmotion, ensurethatonepartmovesbydiatonicstep. In the process of the derivation, several novel rules arise that are not found in treatises on voice-leading. For these novel rules, computer-based score analysis show that composers do indeed write in a manner consistent with these additional rules.
Spectro-temporal factors in the perceptual segregation of tonal sequences
Authors: Singh Punita G. , Bregman Albert S.
Published: October 2005

Spectral factors such as differences in harmonic content are powerful cues in the organization of tonal sequences. Temporal factors such as rise time, however, have been shown to be poor cues [W. M. Hartmann and D. Johnson, Mus. Perc. 9(2), 155–184 (1991)]. The relative salience of these factors was investigated further using complex tones sequenced in a repeating ABA-‘‘gallop’’ format, under conditions in which tones A and B had the same, or different harmonic content and/or temporal envelope shape. The F0 difference between A and B was initially 0 Hz, but increased over the course of a trial, until terminated by a listener, indicating perceptual segregation of the input sequence into sub-sequences comprising A and B tones, respectively. The F0 difference required to reach this segregation threshold provided a measure of the efficacy of stimulus features of A and B as cues for sequential organization. Sequences combining differences in spectral content and temporal envelope shape required the smallest F0 change for segregation. Sequences of tones with the same harmonic structure and temporal envelope required the largest F0 changes, while the other conditions fell in the middle of this range. Results will be discussed in terms of implications for sequential organization as well as for the perception of timbre. [Work supported by NSERC, Canada.]
Rhythm and musical tuning joined in the minds of infants
Authors: Lynch Michael P.
Published: October 2005

Perceptual grouping in music occurs in the context of tuning relations of musical scales, but perceptual relations between rhythm and tuning have received limited study. Because evidence suggests infants perceive rhythm, an important question is whether tuning interacts in the developing mind with other factors contributing to perceptual grouping. Six- and 12-month-old infants detected elongations of silence intervals in 6-note stimuli consisting of two 3-note triads from either the Western major (often heard), Western augmented (seldom heard), or Javanese pelog (culturally foreign) scales. The 2 triads in each stimulus were 1 octave apart, with either the first triad an octave above the second triad, or the reverse. Therefore, the latter but not the former stimuli conformed to the Gestalt principle of good continuation. Elongations of silence intervals were after either the third (between-group) or fourth (within-group) note. Six-month-olds and 12-month-olds performed reliably better than chance only in the testing conditions involving good continuation, and the 12-month-olds’ performance was reliably best in the condition involving also within-group silence elongation and the Western major triad. These findings suggest that good continuation and infants’ perceptual knowledge of tuning characteristics interacted in their perception of auditory groupings. [Work supported by NICHD Grant No. HD28527.]
Detection of regular and irregular repeated tones in noise: Rhythm helps only if rhythm is detected
Authors: Hetherington C. R. , Creelman C. D. , Stuss D. T. , Schmuckler M.
Published: October 2005

Individual thresholds for 1024-Hz, 200-ms tones in noise (PEST, 80% 2IFC) were established in ten listeners, and then tones at this level were presented in a rhythmic pattern or in an irregular temporal pattern with the same average spacing and density of tones. Blocks comprising 200 tones were alternated randomly between the two conditions. A questionnaire administered at the conclusion of the session showed that half the subjects had become aware of the rhythmic pattern. Subjects were separated into two groups for data analysis; those who were aware and those who were unaware of the rhythmic pattern. In a subsequent session, detection threholds were again determined, and the subjects did a five-category rating detection. The rating data showed approximately the detectability predicted by the PEST procedure. No significant difference in this task was found between individuals from the aware the unaware groups. Relative to the detectability established with PEST (d’=1.19), rhythmic presentation yielded greatly enhanced detectability measures in listeners who were aware of the rhythm. Subjects who were unaware of the rhythm showed depressed detectability, both for rhythmic and arhythmic presentation. a)Also at Rotman Res. Inst. of the Baycrest Ctr., 3560 Bathurst Str., North York, ON M6A 2E1, Canada.
Thermoacoustic life sciences refrigerator
Authors: Garrett Steven L. , Gaitan D. Felipe , Perkins David K. , Helseth D. Andrew
Published: October 2005

This thermoacoustic refrigerator is being built to preserve biological samples (blood, urine, etc.) during Space Shuttle operations. It employs two high-power electrodynamic drivers capable of generating 60 W of acoustic power each, two ‘‘stacks,’’ and four internal heat exchangers in order to produce 700 BTU/h (205 W) of cooling in the refrigerator mode at 4 °C and 400 BTU/h (117 W) of cooling in the freezer mode at −22 °C. The working fluid is a 2-MPa mixture of He and Xe gas. Both hot and cold heat exchangers use circulating fluids to remove heat from the insulated sample enclosure and exhaust enthalpy from the engine. This talk will describe the acoustical design and electronic control systems that permit long-term autonomous operation while on orbit. Except for the fact that the entire systems operates from a 28-Vdc power supply, it is not unlike a typical small household refrigerator. [Work supported by NASA—Life Sciences Division and managed by General Electric Government Systems.]
The pathophysiology of presbyacusis: Does the aging cochlea need a jump start?
Authors: Schmiedt Richard A.
Published: October 2005

The Mongolian gerbil is used as an animal model to study the pathophysiology underlying presbyacusis. Gerbils are raised from birth in a quiet vivarium or are exposed to a long-duration wideband noise (0.5–4.0 kHz for 1–2 years at 85 dB SPL) at some time during their life. Quiet-aged ears have thresholds that are increased somewhat, especially above 4 kHz, but nonlinearities such as otoacoustic emissions and two-tone suppression are present and are largely unaffected by the aging process. Morphologically, hair cells in quiet-aged animals are highly conserved, whereas the lateral wall system degenerates, resulting in a decreased endocochlear potential (EP). Current injection to bolster the EP in these quiet-aged ears can enhance the response to low- and high-level stimuli. Noise-aged ears, while also showing increased thresholds, can be differentiated from their quiet-aged counterparts by a lack of nonlinear phenomena. Two-tone suppression is absent as are otoacoustic emissions. Thus, aging in quiet or in noise can have very different outcomes with regard to overall peripheral function, even when the respective audibility curves are similar. [Work supported by NIH P01 DC00422.]
Human infants’ sensitivity to interaural level differences
Authors: Ashmead Daniel H. , Grantham D. Wesley , Murphy Walter , Tharpe Anne Marie
Published: October 2005

Infants’ sensitivity to interaural differences was assessed using a lateralization paradigm. Infants aged 5 to 6 months heard speech sounds with interaural level or time differences (ILD, ITD), while an observer made forced choice judgments about the side of the louder (or leading) sound. In experiment 1 (N=10), the stimuli were 10 dB ILD, 100 dB ILD (monaural), and 400 μs ITD. Performance was well above chance (70%, 74%, and 78% correct), indicating appropriate responses to ‘‘easy’’ interaural differences. In experiment 2 (N=16), a group threshold for ILD sensitivity was determined, using ILDs of 2, 5, 8, and 100 dB (as well as the 10 and 100 dB ILD trials from experiment 1). The threshold estimate was 6.6 dB, far higher than adult thresholds of 0.5 to 1 dB. These findings, together with previous work on infants’ free field sound localization, suggest that ILDs are not a strong basis for sound localization in this age range. [Work supported by NIH.]
Neural processing of temporal gaps in the inferior colliculus of the awake young and old CBA mouse
Authors: Walton Joseph P. , Frisina Robert D. , O’Neill William
Published: October 2005

The ability to detect brief silent intervals or gaps in sound forms one important property of temporal resolution. Psychoacoustical evidence suggests such fundamental processing correlates with more complex perceptions, such as speech perception in noise. Moreover, studies have also implicated deficits in temporal resolution as a possible cause for the difficulties observed in presbycusis. The current study compared neuronal response properties and minimal gap thresholds (MGT) in the young (2–4 month) and old (≳24 month) CBA mouse model of presbycusis. The following measures were obtained from over 40 single units in each age group; intensity functions for 100-ms tone and noise bursts, spontaneous rate, Q10 bandwidth, and gap functions. Neural correlates of gap detection were studied by imbedding a silent gap (widths from 0.5 to 20 ms) between two noise bursts presented at 30 dB above unit threshold. MGT was quantified by comparing spike counts in multiple time windows before, during, and after the gap. Comparison between young and old response patterns indicate: (1) PST histograms displayed numerous patterns including; onset, onset-sustained, on-off, primarylike, buildup, and off responses, (2) a wide range of spontaneous rates were encountered from 0 to 60 spikes/s, (3) MGT varied with response type regardless of age, and (4) the lowest MGTs (1–2 ms) observed were found both in young and old animals, but the frequency of occurrence was lower in the older animals. [Work supported by NIH-NIA P01 AG09524-01A1.]
Directional microphones in computer simulated and real rooms
Authors: Berkley David A. , West James E.
Published: October 2005

Directional microphones are being used increasingly for teleconferencing in a variety of environmental conditions such as varying size and design of the rooms in which they function. However, little is known about the subjective effects of varying environments on the hypothetical improvements produced by these complex microphone systems. It is possible, but quite difficult and expensive, to directly test any proposed microphone system design in a variety of actual or experimental rooms. An alternative approach is use of computer simulation, both of the microphone system and the room environment. A complex microphone system can be modeled as a collection of point microphones distributed in space and summed with appropriate time delays. Established room simulation modeling methods were used. Combining both models together, with appropriate attention to spatial and time resolution of the microphone model, allows calculation of the impulse response of the complete structure, in an arbitrary room environment. The resulting impulse response can be used as a filter for speech. Results of such simulations are presented and compared with real room results.
Observations of humpback whale songs in Australian waters
Authors: Cato Douglas H.
Published: October 2005

Songs of humpback whales have been recorded in Australian waters for more than 10 years, and show features that are broadly similar (though different in detail) to the complex and stereotyped songs observed in the northern hemisphere. Observations have been made along the migration paths that follow the east and west coasts of the continent. Recordings at similar times but separated by thousands of kilometers along a particular coast are similar, but the song off the east coast does not appear to be related to that off the west coast. Both the characteristics of the sounds and the song pattern have changed progressively, but the rate of change has varied substantially from year to year. On the east coast the song has been observed to degenerate from its usual complex pattern to one with little structure, during a year of rapid change, and then return with time to its more usual form.
Modeling vowel identification by listeners: A comparison of cepstrum-based and auditory models at reduced signal-to-noise ratios
Authors: Paschall D. D. , Assmann Peter F.
Published: October 2005

This study compared the abilities of two computational models to predict the identification responses of listeners to vowels presented in quiet and with pink-noise maskers at signal-to-noise ratios (SNRs) of −6, −3, 0, +3, and +6 dB. One model used a representation derived from cepstral analysis. The other used a representation derived from a model of peripheral auditory analysis which (i) filtered the stimulus with a bank of bandpass filters; (ii) compressed the filtered waveforms using a simulation of hair cell transduction; (iii) computed the short-term autocorrelation function of the compressed, filtered waveform in each channel; and (iv) summed the autocorrelation functions across filter channels to generate a pooled autocorrelation function (PACF). Classification was performed by discriminant function analysis, using noise-free tokens as input to the classifier during the training phase. Performance using the cepstrum-based model was better than human listeners in quiet, but deteriorated rapidly with the audition of background noise. In contrast, the PACF-based model performed at levels similar to listeners in quiet, and mirrored their gradual decline in accuracy with decreasing SNR.
Estimation of articulatory-to-acoustic mapping using input and output measurements
Authors: Honda Masaaki , Kaburagi Tokihiko
Published: October 2005

An articulatory-to-acoustic mapping was estimated from real speech data and articulatory data measured by a magnetic position sensing device. The mapping function consisted of an acoustic model of the vocal tract and a multi-layered neural network to map articulatory positions on the midsagittal plane into the vocal tract log area function. Input variables to the network included eight positions on the tongue, lower and upper lip, jaw, and velum as well as two unknown inputs that locally control the log area function below and around the larynx. The weighting variables of the network and the unknown inputs were iteratively trained by the gradient method so as to minimize the cepstral distance between the pre-emphasized input speech spectrum and the synthesized spectrum. When a database consisting of 27 sentences was used to examine the mapping accuracy for a three-layered neural network configuration with 112 hidden nodes, the spectral error of the mapping was 1.3 dB for vowel data and 1.8 dB for sentence data. The mapping accuracy was fair enough for producing natural sounding speech from real articulatory movements.
Linear autoregressive modeling of unvoiced speech
Authors: Kubin Gernot , Atal Bishnu S.
Published: October 2005

Recent interest in nonlinear prediction of speech has brought up the need to assess the performance limitations of linear speech models. While nonlinearity is essential in the sound production mechanisms this need not be reflected in a speech signal model. A linear model may produce the same perceptual effect for a human listener as the nonlinear one. The validity of a linear autoregressive model has been tested for the unvoiced segments of speech. In this experiment, a linear prediction residual is first computed from the speech signal. For unvoiced segments, the residual is replaced by white Gaussian noise with its energy matched every 5 ms. The residual is left unmodified for voiced segments. The linear prediction synthesis filter is excited with the composite residual signal to reconstruct speech. The resulting speech quality has been evaluated in a formal MOS test where 32 listeners rated speech material from 12 speakers uttering 3 sentences each. The present approach yielded an MOS of 4.0. In the same test, 16-bit linear PCM obtained a score of 4.1. In conclusion, a linear model with random excitation is sufficient to reproduce unvoiced speech with very high perceptual quality. A demonstration tape will be played during the presentation.
Binaural masking and lateralization of click trains with alternating interaural time delays
Authors: Balakrishnan Uma , Freyman Richard L.
Published: October 2005

Broadband click trains were used to investigate the effect of onset and ongoing interaural time delays (ITDs) on lateralization and binaural masking. Within a train, successive click pairs had ITDs that were either identical or alternated between two values. The interclick interval was 2 ms and the total duration of each train was 250 ms. Perceived intracranial position of the signals was estimated using an acoustic pointer. Detection thresholds for the same trains were obtained in the presence of a continuous white noise masker with a fixed interaural delay. It was found that lateralization generally followed the ITD of the very first click pair in the train. Masked thresholds were dependent upon the proximity of one or both signal ITDs to the masker ITD, but were independent of the perceived lateral position of the signal relative to that of the masker. These results suggest that while the onset ITD may dominate lateralization for click trains, it has no influence on masked binaural detection of the same signals. [Work supported by NIDCD Grant No. DC01625.]
Horizontal and vertical MAAs for a wide range of sound source locations
Authors: Bronkhorst Adelbert W.
Published: October 2005

Minimum audible angles (MAA) in both the horizontal and the vertical directional were measured for sound source locations distributed over virtually the complete sphere around the listener. Stimuli were noise bursts with either a fixed (flat) spectrum, or a random spectrum with 1/3-octave levels drawn from a uniform distribution with a 20-dB range. It was found that, in general, horizontal MAAs are smallest for sound sources in or near the median plane and vertical MAAs are smallest for sources around 90° azimuth. The results for the random-spectrum stimuli show some unexpected asymmetries. Though listeners were almost unable to localize sources in the median plane with elevations in excess of 30° (vertical MAAs were then 60° or more), they attained moderate MAAs for lower elevations. The MAA for frontal presentation was even similar to the result obtained with fixed-spectrum noise. Results furthermore show that horizontal MAAs for sources at 90° azimuth are much larger for positive elevations than for negative elevations. These findings indicate that localization acuity is optimal for sound sources around or below the horizontal plane.
Asymmetric actuation and sensing of a beam using piezoelectric materials
Authors: Charette François , Plantier Guy , Guigou Catherine , Berry Alain
Published: October 2005

The purpose of the present work is the modeling of a beam actuated by a ceramic piezoelectric on the top with a PVDF piezoelectric on the opposite side acting as a sensor. The two piezoelectric are different in types, may be of arbitrary length and can be positioned independently along the beam. Since there is only one actuator, the asymmetric excitation induces transverse and axial displacement in the beam. This asymmetric actuation contrast with the symmetric actuation normally considered in the literature. Symmetric actuation implies no axial displacement. Here, both piezos are considered perfectly bonded to the beam and the Bernoulli–Euler hypothesis is used for the displacement field. The variational approach with Hamilton’s principle is put to use in the theoretical model. Hamilton’s principle states that the definite time integral of the Lagrangian shall be stationary. This formulation, which is energy based, allows one to consider any boundary conditions and to take into account the dynamic effects of both piezos on the beam response. The theoretical model gives the axial and transverse displacements, the strains, the mean quadratic velocity of the beam, and the voltage of the PVDF piezo sensor as a function of the voltage given to the actuating ceramic piezo. Experimental results are compared to the theoretical model for the case of the beam with free-ends boundary conditions.
Curved piezo-actuator models for vibration control of cylindrical shells
Authors: Sonti Venkata R. , Jones James D.
Published: October 2005

An analytical model of curved piezo-actuators (for active noise and vibration control of cylindrical shells) is developed using Love’s theory of thin shells. It is found that a curved uniformly polarized piezo-actuator of standard size exerts five types of effective forces. The amplitude variation of these effective forces as a function of the actuator thickness shows that some of the forces attain an optimum value for a specific thickness. Also, single-sided and double-sided actuator configurations are examined. The double-sided case includes actuators driven in-phase and out-of-phase. It is found that under some of the various configurations considered above different sets of forces reinforce or cancel each other. The model is developed under the assumption that the actuator size is small in comparison to the cylindrical shell and thus it does not cause any appreciable change in the overall mass or stiffness of the system. The validity of the assumption is tested by evaluating the response of the shell to the actuator in two ways, one neglecting and the other including the mass and stiffness of the actuator.
Active control of radiated noise and vibrations from an automobile fuel tank
Authors: Varadan Vasundara V. , Hong Suk-Yoon , Varadan Vijay K.
Published: October 2005

The use of a co-located piezoelectric, disk-shaped sensor/actuator is described for controlling several modes of vibration of an actual automobile fuel tank that is excited by a shaker. The shaker is attached to the tank where the fuel pump would normally be attached. Single mode control as well as multi-mode vibration control was achieved for both the empty as well as partially filled tank. The radiated noise caused by the structural vibration can also be controlled. Experimental results and short video presentation of the experiment will be made.
Active noise control simulations in a parallelepipedic cavity
Authors: Brunet Serge , Berry Alain , Nicolas Jean
Published: October 2005

Over the last few years, much attention has been focused on the development of active noise control. This development has been spurred by the available low-cost computing power, improvements in actuator technology, and the development of effective control algorithms. Many applications exist for the control of a noise field within complex enclosures such as aircraft, helicopter, and automobile cabins. In order to understand the basic underlying working principles, an analytical model based on a modal approach was developed to simulate the acoustic response of a parallelepipedic cavity (consisting of a flexible simply supported plane structure mounted on a rigid cavity) resulting from the application of acoustic or mechanical excitations on the flexible plane structure. The controllability of the noise field was then investigated with the use of acoustic point sources within the cavity as secondary noise sources and piezoelectric devices on the flexible plane structure as counter vibration sources. The presentation shall consist of a short summary of the analytical model development, results and comparisons for some of the tested control schemes.
Evaluation of speaker normalization methods for vowel recognition using neural network and nearest-neighbor classifiers
Authors: Carpenter Gail A. , Govindarajan Krishna K.
Published: October 2005

Intrinsic and extrinsic speaker normalization methods were compared using a neural network (fuzzy ARTMAP) and L1 and L2 K-nearest neighbor (K-NN) categorizers trained and tested on disjoint sets of speakers of the Peterson–Barney vowel database. Intrinsic methods included one nonscaled, four psychophysical scales (bark, bark with end correction, mel, ERB), and three log scales, each tested on four combinations of F0, F1, F2, F3. Extrinsic methods included four speaker adaptation schemes each combined with the 32 intrinsic methods: centroid subtraction across all frequencies (CS), centroid subtraction for each frequency (CSi), linear scale (LS), and linear transformation (LT). ARTMAP and K-NN showed similar trends, with K-NN performing better, but requiring about ten times as much memory. Among intrinsic methods, ARTMAP and K-NN performed optimally using all the differences between bark scaled Fi (BDA). The ordering of performance for the extrinsic methods were LT, CSi, LS, and CS. For all extrinsic methods, ARTMAP performed best using BDA; K-NN chose psychophysical measures for all except CSi. [Work supported by BP, DARPA, NSF, AFOSR, ONR.]
Hot topics in structural acoustics and vibration
Authors: Tucker Albert J.
Published: October 2005

Acoustic holography has allowed the theoretical concept of identifying and separating radiating supersonic surface waves (identified by low wave numbers) from nonradiating subsonic surface waves (high wave numbers) to be verified experimentally. Frequency-wave-number filtering, which embodies the idea of spatial and temporal filtering, may hold the key for assessing advances in active noise control as well as for developing innovative concepts for damping treatments for passively controlling radiation. For implementation of active control, spatial anti-aliasing filters for sensors and shaped structural actuators (which prevent actuation of high wave numbers) may provide a path to stable active control technology for complex structures. The physical understanding that supersonic radiating waves are membrane waves of structures and fast compressional or shear waves of elastic bodies can lead to new ideas for incorporating damping mechanisms within structures. To extend the concept of spatial-temporal filtering to arbitrary bodies, further analytical, experimental, and signal processing efforts will be required.
Hot topics in speech communication
Authors: Nearey Terrance M. , McGowan Richard S. , Schroeter Juergen
Published: October 2005

In speech perception, the issues emphasized are related to long-term representation of speech units, language-specific differences in speech perception by infants and adults, and some new results from cochlear implant and other hearing research relating to the auditory coding of speech cues. New results on the question of prototypes for speech units and how speaker and contextual variability affect listeners’ behavior are reviewed. Next, there is a survey of recent findings on the effect of language background on infants’ and adults’ perception of speech. Finally, results from perceptual studies of cochlear implant patients involving systematically designed stimulus sets are summarized. In speech production, focus is on the applications of instrumentation, on numerical simulation, and on sensory feedback. There is discussion of measuring instruments that are beginning to provide data on motor compensation and coproduction, and sophisticated numerical simulations that are being developed to answer questions about vibratory mechanisms, air flow, and their relation to sound output. Finally, there is a discussion on the roles of receptor and auditory feedback on articulatory coordination and timing. In speech processing, stress is placed on the progress made in auditory representations, in computational models of language, and in statistical methods for text-to-speech synthesis. In auditory-based representations, 100- to 200-ms speech segments may serve as a basis for distance measures for speech coding that reflect perceptual acceptability of acoustic distortions, and as speech-recognition features that capture dynamic aspects of speech production. In spoken-language processing, the gap between stochastic models of speech (e.g., HMM’s and more traditional models of language structure (syntax) and content (semantics) is being bridged. Finally, text-to-speech synthesis is moving, albeit slowly, from hand-tuned to automatically trained systems.
Is there an across-frequency mechanism sensitive to FM coherence?
Authors: Carlyon Robert P.
Published: October 2005

Much recent research has focused on one’s ability to perform simultaneous comparisons between different regions of a sound’s spectrum. In particular, it has been suggested that the patterns of modulation at the outputs of different ‘‘auditory filters’’ can be compared, and that this ability can be used to group together the commonly varying components of a single source. The case for an across-frequency mechanism that can compare patterns of amplitude modulation (AM) is well established, but that for a corresponding mechanism for frequency modulation (FM) is not. When attempting to identify such a mechanism, it is important to control for the fact that frequency-modulating one component of a harmonic complex out of phase (‘‘incoherently’’) from the rest causes it to become mistuned, and that listeners might detect this mistuning rather than the incoherence perse. This presentation reviews existing evidence that (i) for pairs of inharmonically related tones, listeners cannot discriminate coherent from incoherent FM, and (ii) for harmonic sounds, sensitivity to FM incoherence can be predicted from that to the resulting mistuning. New experiments are described that show that recent contradictory evidence, which has been interpreted as revealing an across-frequency mechanism sensitive to FM incoherence, can be accounted for by the existence of within-channel cues.
Temporal asynchrony and within-signal frequency discrimination for complex tones
Authors: Pollack Irwin
Published: October 2005

Within-signal frequency discrimination for mixtures of two complex tones of different fundamental frequency (‘‘modulation detection’’) was examined under conditions of temporal asynchrony of the individual complex tones. Over a wide range of temporal conditions, the accuracy of discrimination of fundamental frequency: is primarily determined by the temporal overlap of the two complex tones; is independent of the duration of the leading complex tone preceding the mixture; and, is negatively related to the duration of the lagging complex tone following the mixture. The latter result suggests a form of retroactive interference (‘backward masking’) upon the processing of within-signal frequency differences for mixtures of complex tones.
Perception of supraperiodic voices
Authors: Kreiman Jody , Gerratt Bruce R. , Precoda Kristin , Berke Gerald S.
Published: October 2005

The study of voice quality is built largely upon the assumption of vocal (quasi-)periodicity. Supraperiodic phonation types challenge traditional concepts of vocal periodicity, and thus are of theoretic and practical importance, especially when measuring or describing pathologic vocal function. Unfortunately, the literature describing such phonation is confusing. It has been argued [Gerratt etal., J. Acoust. Soc. Am. Suppl. 1 83, S66 (1988)] that the traditional term ‘‘diplophonia’’ has been applied to two distinct phonation types. In one (true diplophonia), the two vocal folds vibrate at different rates, producing a waveform resembling a high-frequency wave modulated by a lower frequency envelope. In the second phonation type (‘‘bicyclicity’’), a pattern of two cycles repeats; cycles within the pattern differ in period and/or amplitude, giving a big–small–big–small appearance to the waveform. To investigate the perceptual characteristics of these phonation types, sets of male and female voices were constructed that included equal numbers of diplophonic, bicyclic, and noisy voices. Expert listeners judged the dissimilarity of pairs of these voices. Multidimensional scaling analyses confirmed that bicyclicity and diplophonia are easily distinguished from each other and from rough or breathy voices. Psychoacoustic studies examining factors underlying the nature of the bicyclic and diplophonic percepts will also be described. Implications of findings for periodicity-dependent models of laryngeal function will be discussed. a)Also at Bell-Northern Res., Verdun, PQ H3E 1H6, Canada.
Radiation and propagation properties of elastic waves on conical shells
Authors: Guo Y. P.
Published: October 2005

This talk discusses the radiation and propagation properties of elastic waves on conical shells by making use of a previously developed theory [Y. P. Guo, J. Acoust. Soc. Am. 92, 2388 (A) (1992)]. The three types of dominant waves in the mid-frequency domain, namely, the compressional, shear, and flexural waves are examined. It is shown that when propagating toward the apex of the cone, shear waves are turned back at caustics but compressional waves are cut off only where they have become subsonic. The radiation losses of these waves are also discussed. It is found that compressional waves radiate much more efficiently than shear waves on a cone, indicating that much less compressional wave energy would be reflected by a cone-shaped endcap. This is indeed what was observed in these scattering experiments.
Effects of click polarity on ABR parameters in the older population.
Authors: Rawool Vishakha W.
Published: October 2005

The auditory brain-stem response (ABR) is known to be useful for detection of acoustic tumors and the onset of symptoms for acoustic tumors is usually between 30 and 50 years of age. Hence, this study was designed to evaluate the effects of stimulus polarity in the older population at intensity levels that are used in obtaining ABRs for clinical diagnosis. Nine subjects between the age of 40–69 years participated in the study. Rarefaction and condensation clicks were delivered at 70 and 80 dB nHL. The latencies were significantly earlier for rarefaction clicks for components II and V (p<0.05). The interpeak interval I–II was significantly shorter for rarefaction clicks than for condensation clicks (p<0.03). The amplitudes of the IV–V complex did not change with stimulus polarity at 80 dB nHL, but at 70 dB nHL larger amplitudes were observed with rarefaction clicks yielding a significant polarity–intensity interaction (p<0.04). The ratio of the IV–V complex with wave I was larger for rarefaction clicks at both the stimulus levels. These results will be discussed in reference to clinical diagnosis and auditory physiology.
Dispersive waves in fluid-loaded, multilayer, composite plates with lossy material
Authors: Kim M. , Hwang Y. F.
Published: October 2005

One of the outstanding features of the multilayer composite plate is that it can be tailored for a specific structural-acoustic application by intelligently arranging the various layers of elastic and viscoelastic materials. In this study, the multilayer composite plate under consideration possesses a layer of viscoelastic material with high material loss factor for attenuating the propagating waves. For a fluid-loaded case, certain propagating modes dissipate their energy through radiation into surrounding fluid medium, and decreases in amplitude in the direction of propagation even if no material loss factor is assumed. Study of the wave dispersion of this composite plate indicates that the dispersion characteristics and the mode shape of the propagating wave are affected by the amount of damping in the viscoelastic material. The reasons for the aforementioned effect are discussed. Numerical examples are presented for various plate configurations with the viscoelastic layer given a range of material loss factor. [Work supported by ONR.]
Use of continuous wave ultrasound for measurement of the dynamic response of soft tissue to facilitate diagnosis of disease
Authors: Hastings Mardi C. , Schroeder Lee E.
Published: October 2005

A noninvasive, noncontact ultrasonic system for measurement of amplitudes of vibration of soft tissue has been developed for operation in air. The measurement method, based on phase modulation of low power, continuous wave ultrasound, was originally developed by Rogers and Hastings [U.S. Patent No. 4,819,643 (11 April 1989)] to measure the frequency response of auditory organs in fish underwater. In this study, the technique was used to measure the response of corneas of enucleated bovine eye globes to acoustic excitation at audible frequencies in air. Data were recorded at different levels of intraocular pressure (IOP) which is routinely clinically measured to screen for glaucoma. A mathematical model for harmonic motion of the corneal shell was developed for correlation with empirical results. The stiffness and natural frequency of the thin corneal shell are functions of IOP; thus the data provide a noncontact measurement of this parameter. This ultrasonic measurement technique eliminates the problems associated with current contact tonometry methods which include maintaining sterility, abrading the corneal surface, and inherently altering the IOP. [Work supported by NSF Grant No. MSS 9058607.]