bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound transmission through an aeroelastic plate into an acoustic cavity.
Authors: Clark Robert L. , Frampton Kenneth D.
Published: October 2005

The transmission of turbulent boundary layer (TBL) pressures into acoustic enclosures is very important to the aerospace industry. This topic is particularly important in aircraft interior noise investigations. While many studies have been published concerning TBL transmission through elastic plates into acoustic enclosures, few of these studies have considered the dynamic effects of aerodynamic flow over the plate (i.e., aeroelasticity). This presentation investigates the modeling of an elastic plate subject to full potential flow and TBL loading on one side and coupled to a reverberant acoustic enclosure on the other side. The elastic plate and acoustic enclosure are modeled through a Rayleigh–Ritz approach. The effects of the external fluid flow are modeled through a singular valued decomposition technique which performs a system identification on an approximate numerical solution to the full potential flow equations. This aerodynamic model is then coupled to the elastic plate/cavity model to form the complete system. The primary focus of this investigation is the effects of the external flow on the sound transmission through the elastic plate into the cavity. It is demonstrated that external flow can significantly affect the system dynamics and, hence, the sound transmission.
Discontinuous constrained layer damping treatments applied to a vibrating free-free beam.
Authors: Uppal Samir , Flatau Alison B. , Bailey Theodore B.
Published: October 2005

The vibration response to application of discontinuous constrained layer damping (CLD) patches to varied portions of a free-free beam was studied. Since neither closed-form solutions nor finite element methods can be readily implemented for CLD analysis with partial coverage of a structure under broadband excitation [C. T. Sun and Y. P. Lu, Vibration Damping of Structural Elements (Prentice-Hall, Englewood Cliffs, NJ, 1995), pp. 318–362], an empirical approach was taken. The test object was a 26.5- × 1- × 1/8-in. steel beam, and was subjected to a chirp. The aim was to quantify the relative effectiveness of varied lengths and positions of CLD patches in reducing the response of the first five resonant modes of the beam. Assessment of the potential for strain energy dissipation was made based on the net displacement of the beam (appropriately phased mode summation), with relative phase of the summed modes specific to the input force signal. Attempts were made to correlate the effect of CLD on each mode to the time-averaged percentage of strain energy for that mode under the treatment patch, coupled with the percentage of the beam’s strain energy under the patch. [Work supported by NSF.]
Simulations of temporal resolution and integration data with a computer model using a modulation filter bank.
Authors: Münkner Stefan , Kohlrausch Armin
Published: October 2005

Temporal resolution and temporal integration in the auditory system, with their conflicting time constants, are often regarded as paradox phenomena. In this study a model is presented for the simulation of a number of temporal resolution experiments (e.g., gap detection, forward masking) and classical test tone integration data (cf. contributions by Dau et al.). The model consists of two major parts. A preprocessing stage that transforms the acoustic stimulus into an internal representation, simulating the peripheral processing in the auditory system. Processing errors are accounted for by adding internal noise which introduces detection limits. The second stage is an optimum detector to simulate a ‘central’ decision device. The preprocessing stage consists mainly of three subunits: a Gamma tone filterbank to simulate peripheral filtering; a set of adaptive feedback loops that derives an adapted envelope of every peripheral filter output; a modulation filterbank (per peripheral channel) that analyzes stimulus periodicities in these adapted representations. The model is able to simulate gap detection and test tone integration experiments quantitatively without changing its parameters. It can be shown that within this model the modulation filterbank is vital to achieve this performance. [Supported by the DFG (Az. Mu/1201).]
New masking experiments using low-noise noise maskers.
Authors: Kohlrausch Armin
Published: October 2005

Low-noise noise generally refers to narrow-band noise with a flat temporal envelope. Hartmann and Pumplin [J. Acoust. Soc. Am. 83, 2277–2289 (1988)] used one 100-Hz-wide low-noise noise sample to mask a sinusoidal signal, and found that thresholds were 5 dB lower than for a comparable Gaussian noise. These experiments were performed as frozen-noise measurements and the threshold values were the averages of the results for six different signal starting phases. The thresholds for the signal in Gaussian noise (about −11-dB signal-to-overall-noise ratio) were considerably lower than thresholds typically found in a random-noise presentation (−3 dB). The experiments reported here were initiated to test whether the difference in masking behavior between low-noise noise and Gaussian noise is also observed in a random-noise experiment and how it depends on masker bandwidth and signal duration. In a 100-Hz-wide masker centered at 1000 Hz, the same difference of about 5 dB was found. This difference increases with decreasing masker bandwidth, reaching a maximum of 9.5 dB for a 10-Hz-wide masker. The difference also increases somewhat with decreasing signal duration, from 5 dB for a 500-ms signal to 7.6 dB for a 20-ms signal.
(Bragg mode)-(leaky mode) coupling due to a finite periodic array of scatterers on a submerged elastic layer.
Authors: Nagem Raymond J. , Felsen Leopold B. , Collins Brian J.
Published: October 2005

Coupling of energy into and out of submerged layered elastic topographies via scattering centers on the top surface is of interest for a variety of applications in bottom-interacting acoustics. To understand and parametrize the basic wave phenomena which are operative here, this study was begun with a simple model wherein a finite periodic array of scatterers situated on a single elastic layer is insonified by an incident plane wave. The problem is analyzed rigorously by spectral wave-number decomposition, and the scattered fields are obtained by asymptotic evaluation of the spectral intergrals. The results can be interpreted in terms of array-modified leaky waves and slab-modified Bragg modes, with Bragg-leaky mode coupling occurring due to end effects as well as bulk effects of the array. The coupling effects are optimized when one of the slab-modified modes is phased matched to one of the Bragg modes. The asymptotic algorithms are calibrated against numerically evaluated spectral integral reference solutions. Windowed space-wave-number processing is then applied to extract the above phenomenology from the reference data.
High-frequency backscattering by thick finite cylindrical shells in water at oblique incidence: Experiments and calculations.
Authors: Morse Scot F. , Marston Philip L. , Kaduchak Gregory
Published: October 2005

Various authors have demonstrated the importance of plotting backscattering amplitude as a function of both aspect angle and frequency for thin cylindrical shells in water. Some interesting features of analogous plots for a thick finite cylindrical shell with the frequency range extending above the coincidence region have been investigated. Impulse response measurements taken with an improved PVDF sheet source [Kaduchak et al., J. Acoust. Soc. Am. 97, 2699–2708 (1995)] reveal a backscattering enhancement in the coincidence frequency region for aspect angles in the vicinity of end-on incidence. Though the cylinder was capped, the features of interest appear to be identified with waves on the coupled shell–fluid system. Similar features are present in backscattering computations for a simply supported thick cylindrical shell and they may be useful in high-frequency inverse scattering. [Sponsored in part by the Office of Naval Research and by the UT:ARL Independent Research and Development Program.]
Temporal coordination of articulator gestures.
Authors: Wood Sidney A. J.
Published: October 2005

Movement data are analyzed to elucidate principles of articulator coordination. Procedures for tracking articulator gestures from x-ray motion films, and results obtained from Swedish and Bulgarian work are reported in Wood [J. Phon. 19, 281–292 (1991), Proc. 3rd Congress I.C.P.L.A., 191-200, Helsinki (1994), Proc. 13th I.C.Ph.Sc., Vol. 1, 392–395, Stockholm (1995), J. Phon. (in press)]. Coarticulation and gesture conflict have been studied. The domain of coarticulation has been seen variously as a between-target transition, or comprising of one or two phonemes on either side. These are usually presented as rival solutions, but the present data show speakers using all three schemes. The pertinent question is how does a speaker select one of them. For gesture conflict, there are two approaches. The one feeds all gestures to the musculature where conflicts are resolved by summing rival forces. The second modifies motor input by queuing antagonistic gestures in order to avoid conflicts. All potential gesture conflicts in the present data were resolved by queuing gestures. The data to be reported here include Eskimo to provide a further test on the universality of these principles for articulator coordination. [Work supported by Swedish Research Council for Humanities and Social Sciences.]
Study of the acoustic-to-articulatory transformation for vowels and fricatives.
Authors: Riegelsberger Edward L. , Krishnamurthy Ashok K.
Published: October 2005

Using synthetic speech from an articulatory speech synthesizer, statistics are generated of the error between actual articulatory configurations and those estimated by an acoustic-to-articulatory mapping routine. Based solely on acoustics, neglecting aerodynamic and perceptual issues, histograms of total estimation error suggest that the inverse problem is no more ambiguous for fricatives than for vowels. By examining the error covariance, dominant articulatory dimensions are identified in the fricative model that have the greatest effect on the acoustic transfer function and, as a result, are better estimated by the acoustic-to-articulatory mapping routine. Weak articulatory dimensions are also found that the acoustic-to-articulatory mapping routine can barely estimate better than simply guessing. Suggestions are made for ways in which these error statistics, and specifically the knowledge of the unequal importance of different articulatory dimensions, can be used to motivate improved techniques for the acoustic-to-articulatory mapping of speech. Demonstrations of some of these ideas will be given on real and synthetic speech. [Work supported by the AFOSR.]
The McGurk effect for non-native speech sounds perceived as nonspeech.
Authors: Brancazio Lawrence
Published: October 2005

The McGurk effect—the integration of visual information into speech perception—is well documented for English consonants. However, a recent attempt to extend the effect to musical events (violin plucks and bows) showed only a weak visual influence on perception [Saldaña and Rosenblum, Percept. Psychophys. 54, 406–416 (1993)]. Thus the conditions required to produce a strong McGurk effect are unknown. The effect may be specific to perception of native phonological categories; alternatively, it may apply to dynamic vocal-tract events in general. This study tested for a McGurk effect with click consonants, which are phonological in some African languages, but are treated as nonspeech by English speakers [Best, McRoberts, and Sithole, JEP:HPP 14, 345–360 (1988)]. Audio bilabial, dental, and lateral clicks, spoken in isolation and coarticulated with a vowel, were dubbed onto video presentations of each click. Parallel stimuli were made from English stops in syllables and with their excised bursts only. English-speaking subjects made bimodal matching judgments on the dubbed stimuli. Results revealed a visual influence on perception of the non-native sounds that was somewhat weaker than for native speech, although stronger than Saldaña and Rosenblum’s effect for violin sounds. [Work supported by NIH.]
Interface waves in seafloor propagation and scattering problems.
Authors: Stephen Ralph A. , Bolmer S. Thompson
Published: October 2005

Interface waves often play a significant role in seafloor propagation and scattering problems. Because they are not solutions to the pure acoustic wave equations, but require a nonzero shear modulus, they are frequently overlooked in model and inversion studies. There are two areas in particular where interface waves are relevant in underwater acoustics: (1) when the source and receiver are close (in terms of wavelengths) to the seafloor, and (2) when interface roughness or heterogeneities near the interface act as secondary scatterers. The first case is important for low-frequency propagation in shallow water. The second case is important in scattering problems such as low-angle, monostatic backscatter or the scattered field of seafloor or buried ordinance. Insight into the generation and propagation mechanisms of interface waves can be gained through time-domain shapshots of the wavefield and by analysis of time series record sections. Animations of wavefront propagation in vertical slices through the seafloor show clearly the energy partitioning between the various body and interface wave types. [Work supported by ONR.]
Wave field visualization as an interpretational tool in borehole geophysics.
Authors: Rao V. N. Rama , Schmidt Henrik , Vandiver Kim
Published: October 2005

A hybrid model for computing the radiation from a borehole while drilling has been developed. A model for modal propagation in a radially layered borehole is coupled with the OASES code for full wave modeling of the resultant seismic wave field. The coupling is performed using the concept of effective sources. First, an equivalent seismic source array that produces the same far-field radiation as the borehole is determined. This source array is then introduced into the layered earth model and the resulting seismic field is computed. Three propagating modes exist in the borehole in the presence of the drill-pipe. The individual modes radiate into the formation in a pattern that is dependent on geophysical properties, with the resulting radiation pattern being extremely complex and difficult to interpret physically. Here, visualization and animation in particular has proven to be an extremely useful tool. For example, animation allows the direct identification of the complex arrival pattern recorded on surface mounted geophones. The fundamental differences between the radiation patterns in fast and slow formations are also clearly demonstrated using computer visualization and animation.

Standards Committee S12 on Noise. Working group chairs will report on their progress for the production of noise standards. The interaction with ISO/TC 43/SC1 and ISO/TC 94/SC12 activities will also be discussed, with reference to the international standards under preparation. A report will be given on the meeting of ISO/TC 43/SC1 in Pretoria, South Africa, held in February 1996. The Chairs of the respective U.S. Technical Advisory Groups (H. E. von Gierke and E. H. Berger) will report on current activities of these international Technical Subcommittees under ISO. Scope of S12. Standards, specifications and terminology in the field of acoustical noise pertaining to methods of measurement, evaluation, and control; including biological safety, tolerance and comfort and physical acoustics as related to environmental and occupational noise.
Assessment of HVAC sound power data for sensitive spaces.
Authors: Miller Kevin C. , Beam Martin J.
Published: October 2005

Certification testing of air handling unit sound power (PWL) indicates that individual unit PWL can vary significantly from manufacturer published data. Published data are typically based on a limited number of actual tests with results extrapolated for other fan sizes and operating conditions. Although published data are normally acceptable for routine applications, indiscriminate use for sensitive designs (studios, theaters, conference centers, etc.) can result in excessive finished space noise levels. The fact that the design goals have been exceeded can be accurately documented. The exact reason for the exceedance, however, cannot be as firmly established in a complex system. Certification PWL testing of air handling units prior to installation can detect PWL variations from the published data. Individual unit PWL certification was often not cost effective prior to the developement of sound intensity and the establishment and use of recognized standards for in situ PWL testing (e.g., ASA 104-1992, ANSI S.12.12.1992). Case histories to be presented document fan PWL variations from published data of up to 10 dB and higher in certain octave bands.
Air pedestal diffusion method of introducing air silently to spaces.
Authors: Essert Robert , Doria Damian
Published: October 2005

In recent years the drive to air condition performance halls with greater energy efficiency and comfort has brought supply air terminals closer to the ears of audience members. Introduction to North America of the European approach of air volume displacement has required development of silent air terminals that coordinate with audience seating and allow greater efficiency and comfort. Artec Consultants Inc. has worked with leading seating manufacturers to develop pedestal chair supports and other floor mounted devices that function as terminals for air supplied from underfloor plena. The Ford Centre in North York Ontario incorporates one such design, as will several additional facilities in North America and Europe that are presently under construction. Completed facilities have met the design noise levels. This paper will examine the recent development of these terminal devices and discuss the benefits and complications associated with their implementation.
The influence of fans on low-frequency noise and rumble in HVAC systems.
Authors: Lilly Jerry G.
Published: October 2005

Low-frequency noise and rumble problems can occur in HVAC systems due to problems with the fan, the duct sytem, the fan/duct interface, and even the control system. This discussion deals with fan related problems only. Items that will be discussed include: the importance of fan-type selection (centrifugal, axial, plenum, etc.), selecting the right fan size for the required duty, the importance of aerodynamic conditions at the fan inlet and outlet, and the problems associated with VAV control mechanisms. The discussion will also address the importance of proper vibration isolation and how to prevent common problems. Specific project examples will be included.
Computer program for conducting acoustical analyses of HVAC systems.
Authors: Reynolds Douglas D. , Mitchell Scott C.
Published: October 2005

An interactive Windows-based computer program has been developed that can be used to conduct complete acoustical analyses of HVAC systems. The program can be used to track sound from a HVAC sound source such as a fan to a room. Both sound from a single path between a sound source and room or from multiple paths between a sound source and room can be investigated. The program has a full set of editing features that include change, delete, and insert options which allow an individual to interactively design an HVAC system to meet specified acoustic design criteria. Design templates for systems in which multiple acoustical analyses will be conducted can be developed and stored to minimize the time associated with inputting data to the program. The program has options for printing out tabulated results and noise criteria and room criterion curves for inclusion in reports.
Interindividual variation in the songs of humpback whales.
Authors: Frankel Adam S.
Published: October 2005

The function of humpback whale song remains elusive. Humpbacks primarily sing on the wintering grounds. Many hypotheses suggest a male advertisement function. It has been suggested that all whales of a population sing the same version of song, and its structure slowly evolves during and between singing seasons. Field observations of 1989 song indicated substantial variation in the song of humpbacks. The question remained, were the differences between individuals greater than those between successive songs of an individual. The songs of 11 whales were sampled during an 8 day period, to reduce the probability that song evolution would affect the results. Six units from three themes were sampled from four songs from each whale. Unit duration, lowest frequency, bandwidth, frequency of peak amplitude, and source level were measured. A repeated measures ANOVA found significant differences between individual whales and no such differences were found between successive songs of the same individual. These data indicate that there are real measurable differences between the songs of different individual whales. These individual differences could be used as a basis for female choice of males, based on song features. While this remains untested, these data are necessary for such a hypothesis.
Interspecific versus intraspecific variation in alarm call vocalization among two species of capuchin monkey.
Authors: Norris Kimberly S. , Norris Jeffery C.
Published: October 2005

Inter- and intraspecific variation in alarm calls were compared for two species of free-ranging capuchin monkey: the wedge-capped capuchin (Cebus olivaceus) and the white-faced capuchin (Cebus capuchinus). Alarm calls in each case were made in the presence of the same predator, a boa constrictor. Vocalizations (n=40) were compared for commonly examined acoustic parameters (e.g., signal duration, frequency, and amplitude variables), as well as for vocal features found to be acoustic cues to the monkeys [e.g., bandwidth of dominant formant; change in frequency of the dominant formant (see Norris, 4aAB3)]. Additionally, correlations of spectrograms were performed using CANARY. Interspecific variability was found to be significantly greater than intraspecific variability for signal duration (F=45.30;p<0.0001), maximum frequency (F=8.52; p<0.0059), and formant number (F=10.32;p<0.0027). However, interspecific variability of calls was not significant for any of the acoustic parameters found to be used as perceptual cues for the two species. The evolutionary and ecological significance of these findings will be discussed.
Spectrogram contour features for intraspecific classification of narrow-band animal sounds.
Authors: Pinkowski Ben
Published: October 2005

Recent research has indicated that contour features obtained from computer imaging are useful for characterizing some interspecific differences in narrow-band animal sounds [B. Pinkowski, J. Acoust. Soc. Am. 95, 3419–3423 (1994)]. Contour features may also characterize the intraspecific differences of animal sounds that vary among individuals. To examine this possibility, six songs from each of ten eastern bluebirds (Sialia sialis) (5 males and 5 females) recorded during 1991 and 1992 in southwestern Michigan were digitized at 22 kHz, converted to spectrogram images, and analyzed for contour using Fourier descriptors (FD’s). Following smoothing, thresholding, and segmentation, the spectrogram components corresponding to three or more basic notes were merged by a simple pixel aggregation algorithm to yield a single contour per song. The contour border was then used to compute a 512-point DFT. With 16 low-order FD’s per song, 58 of the 60 songs (96.7%) were correctly classified by a linear discriminant function. Male songs were more varied and complex and hence more difficult to classify by contour alone than were female songs. [Work supported by NIH.]
Acoustic communication by imported fire ants.
Authors: Hickling Robert , Wei Wei , Lambert Lavone
Published: October 2005

Although it is well known that ants generate sound by stridulation using gaster-flagging motion of the abdomen, acoustic communication by ants is generally believed to be almost nonexistent compared to chemical communication using pheromones [Holldabler and Wilson, The Ants (Harvard U. P., Cambridge, MA, 1990), pp. 255–259]. Contrary to this prevailing belief, it has been found that imported fire ants can use acoustic signals for meaningful communication. Signals have been recorded in situations such as alarm, distress, and attacking prey and also what appears to be an all’s-well signal. These were analyzed and distinct time-modulation differences were found depending on the situation. Acoustic signals appear to be used for urgent communication. Ant response provides an indication of the significance of the signals. The frequency range is principally below about 2 kHz. The sound-pressure level of a general alarm signal was found to be approximately 40 dB (A), which is about three times the level of a faint whisper. Background noise inside an ant mound is low and interior tunnels can act as waveguides.
An acoustic perception model for echolocation signals.
Authors: Palakal Mathew J. , Murthy Uday , Wong Donald
Published: October 2005

Bats that echolocate using biosonar pulses perceive their target as an auditory image by extracting acoustic cues conveyed in the target-reflected echoes. Neurophysiological studies suggest that a large majority of cortical neurons found in FM bats are delay sensitive. Moreover, these neurons are tonotopically organized and have a best delay (BD) at which they respond maximally to an input stimulus. In order to understand the role of these neurons during pulse-echo processing, a mathematical model capturing the functionality of delay sensitive neurons (DSN) has been developed. As a first approximation, response to a pulse-echo pair of a DSN is derived as, y(t)=exp[−i*(β−δ)2/2*σ2], where β is best delay of the neuron, δ is arrival time of the echo, i is neural spikes, and σ is delay range of the neuron. A two-dimensional cortical response map (CORMAP) of DSNs is then developed based upon the best frequencies and the above stated response property with varying BDs. The CORMAP is then simulated using phantom targets containing multiple echoes. Once a pulse is sent and as the echoes begin to arrive for every δk, the CORMAP generates a response map as the DSNs fire. The firing patterns occur at various δk can be analyzed to estimate target distance and structural information. [Work supported by NSF.]
The effects on comodulation masking release of systematic variations in on- and off-frequency masker modulation patterns
Authors: Buss Emily , Richards Virginia M.
Published: October 2005

Detection thresholds were obtained for a 500-Hz tone added to a masker comprised of an amplitude-modulated tone centered at the signal frequency (on-frequency masker) and an array of amplitude modulated tones centered at 300, 700, 800, 900, 1000, and 1100 Hz (off-frequency maskers). The shapes of the amplitude modulation patterns of the on- and off-frequency maskers were either matched or mismatched. In the shape-matched conditions the on- and off-frequency masker modulation patterns were the same, either sinusoidally or square-wave amplitude modulated. In the shape-mismatched conditions, the on-frequency masker was sinusoidally amplitude modulated and the off-frequency maskers were square-wave amplitude modulated. The rate of modulation was either 10 or 20 Hz, and the duty cycle of square-wave modulation was systematically varied. The relative phases of the on- and off-frequency modulators were either in-phase, out-of-phase, or random-phase. Comodulation masking release (CMR) was defined as the difference between thresholds in the in-phase and random-phase conditions. CMRs as large as 12 dB were obtained for the shape-matched as well as the shape-mismatched conditions. Thresholds in the out-of-phase condition were on average 2.6 dB higher than those in the random-phase condition. Results are consistent with a cued listening model where off-frequency modulation minima trigger sampling at the output of the auditory filter centered on the signal frequency.
The modal density of anisotropic structural components
Authors: Langley R. S.
Published: October 2005

The modal density of a structural component is a key parameter in high-frequency vibration prediction techniques such as statistical energy analysis (SEA). A study of the literature reveals that the standard method of computing the modal density of a two-dimensional component, such as a plate or shell, is restricted to orthotropic components. This method (which is usually referred to as Courant’s method) is extended here to a generally anisotropic component by considering initially the case of periodic (or Born–von Kármán) boundary conditions. It is then shown that the resulting modal density is independent of the nature of the actual boundary conditions which act on the component. On a related issue, doubts have been expressed in the literature as to whether the results yielded by Courant’s method are applicable to general boundary conditions if the component exhibits degeneracy of the dynamic edge effect; the present analysis demonstrates that the method is in fact valid in such cases. The developed technique is applied to the bending vibrations of an anisotropic plate, and good agreement is found with empirical results for the modal density derived from natural frequency computations.
Lord Rayleigh and reciprocity in physics
Authors: Cook Richard K.
Published: October 2005

The reciprocal theorem of mathematical physics was not originated by Rayleigh. However, the theorem is presented, in several forms, with elegant clarity in his Theory of Sound. Since its publication his book has influenced generations of physicists, particularly those working in acoustics. When combined with the parallel reciprocal theorem of electric-circuit theory, it has proved to be invaluable to the subject of electroacoustics, on which is based the modern technology of acoustical measurements. In the ensuing 100 years since publication of his book, physicists have found the reciprocity principle to be valid in many areas of physics. However, the principle is not universally valid; we describe physical systems to which an antireciprocal theorem applies. Kelvin–Tait had, in effect, developed an antireciprocal theorem (for gyroscopic forces proportional to velocities) in a nonconservative mechanical system. The results in their 1879 book were introduced by Rayleigh in his second edition (1894), but without identification of an antireciprocal theorem. Particularly in the electroacoustics of transducers—microphones and loudspeakers—application of the reciprocal and antireciprocal theorems are of comparable usefulness. The latter theorem may be said to date from Faraday’s discovery of electromagnetic induction in 1831; the electrocmechanical action of an electromagnetic motor–generator satisfies an antireciprocal theorem.
Across-frequency processing of multiple modulation patterns
Authors: Grose John H. , Hall Joseph W.
Published: October 2005

This study sought to determine the degree to which the auditory system can perform simultaneous across-frequency analyses on concurrent, but independent, modulation patterns. This was tested by measuring detection of a multicomponent signal presented against a background comprised of multiple modulation patterns. The results indicated that independent comodulation masking releases (CMRs) could occur simultaneously, but only if the independent modulation patterns were restricted to relatively discrete frequency regions. Moreover, the analysis accomplished in each region did not appear to be optimal. This suggests that there are limits to the independence with which simultaneous across-frequency analyses can be performed.
The two-sound-pressures theorem for aerodynamic sound generated by two-dimensional flows
Authors: Henderson Brenda
Published: October 2005

The three-sound-pressures theorem [A. Powell, J. Acoust. Soc. Am. 34, 902–906 (1962)] applies to sound generated by inviscid, low Mach number, free flows when the source region is acoustically compact and shows that the acoustic far field must be reducible to lateral quadrupole radiation only. In two dimensions, the source region is not compact in the third dimension so it is not obvious that the three-sound-pressures theorem directly applies in this case. The two-sound-pressures theorem is developed and is shown to be satisfied by two-dimensional lateral quadrupole radiation.
Flexural wave reduction using a compliant tube baffle
Authors: Ko Sung H.
Published: October 2005

A theoretical model was developed to evaluate the reduction of flexural wave that is generated by a line force applied on an infinite plate using a compliant baffle. The compliant baffle layer placed between the plate excited by a line force and a signal conditioning plate is designed for reducing pressure fluctuations from the vibrating plate. The baffle layer considered here is the compliant-tube array, modeled by Junger [J. Acoust. Soc. Am. 78, 1010 (1985)] to represent a homogeneous (dispersive) fluid layer. Effects of various parameters such as the aspect ratio of the compliant tube, the distance between tubes, and the damping of the tube material on the flexural wave reduction are presented. Calculations of noise reductions were made for both the dispersive and nondispersive fluid baffles.
Influences of phonetic identification and category goodness on American listeners’ perception of /r/ and /l/
Authors: Iverson Paul , Kuhl Patricia K.
Published: October 2005

Recent experiments have demonstrated that category goodness influences the perception of vowels [Iverson and Kuhl, J. Acoust. Soc. Am. 97, 553–562 (1995)]; listeners show a perceptual magnet effect characterized by shrunken perceptual distances near excellent exemplars of vowel categories and stretched distances near poor exemplars. The present study extends this investigation by examining the relative influence of phonetic identification and category goodness on the perception of American English /r/ and /l/. Eighteen /ra/ and /la/ tokens were synthesized by varying F2 and F3 frequencies. Adult listeners identified and rated the goodness of individual stimuli, and rated the similarity of stimulus pairs. Multidimensional scaling analyses revealed that the perceptual space was shrunk near the best exemplars of each category and stretched near the category boundary. In addition, individual differences in /r/ identification corresponded to the degree of shrinking near the best exemplars of the /r/ category. The results demonstrate that category goodness and phonetic identification both contribute to the perception of /r/ and /l/.
Learning voices.
Authors: Nygaard Lynne C. , Pisoni David B.
Published: October 2005

The present experiment was designed to investigate the perceptual learning of talker’s voice. Listeners were trained over a 9-day period to become familiar with a set of ten talkers (five male and five female). During each day of training, listeners were asked to identify talkers’ voices from isolated words and to associate each voice with a common name. On the tenth day of testing, listeners were given a generalization test which consisted of a set of novel words produced by the ten talkers they heard in training and by ten unfamiliar talkers (five male and five female). The results showed that over 9 days of training, talker identification performance improved. However, there were large individual differences among listeners in talker learning performance. In addition, individual differences in the identifiability of voices was observed. Male voices were identified significantly better than female voices by both male and females listeners. The results of the generalization task showed that the introduction of unfamiliar voices reduced identification performance for familiar talkers. Listeners were able to judge overall familiarity, but confusions increased in identification of familiar talkers. The results suggest that talker-, listener-, and task-specific factors influence the perceptual learning of talker’s voice.
Perceptual compensation for vowel undershoot may be explained by general perceptual principles.
Authors: Holt Lori L. , Lotto Andrew J. , Kluender Keith R.
Published: October 2005

When presented a series of /dVd/ syllables varying perceptually from /dεd/ to /d■d/, listeners identify the vowel sound as /■/ more often than when the vowels are presented alone as steady states. Conversely, /bVb/ series lead to more /ε/ identifications. This pattern of responses appears to demonstrate a compensation for assimilatory effects of coarticulation or vowel ‘‘undershoot.’’ Experiments will be presented which test the specificity of this perceptual process. Two ten-step (/bVb/ and /dVd/) series of 100-ms /CVC/ syllables varying in F2 midpoint frequency (1260–1710 Hz) were synthesized. Nonspeech analogs were created by appending 70-ms sine-wave glides, which followed a similar trajectory to F2 in the speech stimuli, to 60-ms steady-state vowels varying in F2 frequency. A second set of nonspeech series was created by appending constant-frequency sine-wave tones to the vowel stimuli. The frequency of these tones were set at the F2 starting frequencies for the speech stimuli. These nonspeech contexts had effects on vowel identification that were analogous to those for the speech contexts. Lower frequency glides and tones (modeling /bVb/F2) led to more /ε/ (higher F2) identifications with the complementary pattern for higher frequency glides and tones. [Work supported by NIDCD and NSF.]
Vowel discrimination in a phonologically neutralized context.
Authors: Fox Robert Allen , Tran Son
Published: October 2005

The perception of vowel quality is not only affected by the formant structure of the vowel, but by the nature of the surrounding phonetic context. For example, it has been demonstrated [R. A. Fox, in Speech Perception, Production and Linguistic Structure, edited by Y. Tohkura et al. (IOS Press, 1992)] that listeners’ ability to make reliable vowel quality distinctions are lowered when the vowels are placed in a context that introduces phonological neutralization (e.g., post-vocalic [■]). One possible explanation for this phenomenon is that of listener bias, which should be eliminated using the appropriate signal detection methodology. The present study describes the results of an experiment that obtained d’ measurements of one-step differences in an [i]-[■] continuum in CV, CVr, CVl, and CVd contexts under fixed-level, minimum uncertainty conditions. Results demonstrate after several days experience with the stimuli and methodology that the discrimination differences as a function of context were eliminated. However, a post-training identification test still showed context effects on vowel categorization. These data will be discussed in terms of the possible nature of this listener bias in vowel perception.
Age-related changes in the categorical perception of stop consonants.
Authors: Slawinski Elzbieta B.
Published: October 2005

The study focused on changes in the categorical perception of intial stop consonants as a function of age and hearing status. The identification of intial stop consonants differing in voicing and place of articulation relies on an integration of multiple acoustic cues (VOT, character of the noise burst, onset frequency and direction of the second and third formant transitions). Four hundred subjects, divided into four age groups (20–85 years) and into three hearing groups, participated in experiments that required the identification of syllables [ba] or [pa] and [ba], [da], or [ga] along synthesized continua. Stimuli were presented to subjects via headphones at 75 dB SPL. Results demonstrated that the phonemic boundary of the [ba–pa] continuum was shifted towards a longer VOT as a function of age and hearing status. Moreover, the phonemic boundaries between [ba] and [da], and between [da] and [ga], demonstrated by older and hearing impaired subjects were shifted toward [d] and [g] categories as compared to young subjects with normal hearing. The observed changes may be due to the age-related deterioration of ability to analyze brief signals and ability to integrate multiple acoustical cues. [Work supported by Health and Welfare of Canada.]
An investigation of computational problems associated with resonant ultrasound spectroscopy.
Authors: Spoor P. S. , White P. J. , Maynard J. D.
Published: October 2005

At a previous meeting (June 1995) a report was given on anomalous behavior of the Rayleigh–Ritz method for calculating the normal mode frequencies of elastic solids (the method that forms the basis for most resonant ultrasound work), when those solids had the shapes of slightly perturbed parallelepipeds. These shapes are of interest to understand the effects of sample preparation errors on the overall elastic constant determination. In an effort to understand these effects, a systematic study of the various interrelated computational issues in RUS has been undertaken. Attempts are made to address the following issues: (1) whether the anomalous behavior of the Rayleigh-Ritz solutions is algorithmic or numerical; (2) whether these anomalies may result from problems with the inverse calculation (where the frequencies are inverted to obtain elastic constants) as well; and (3) what relationship exists between the RMS error in the frequencies and the confidence in the elastic constant determination. Results will be shown comparing analyses of actual data with and without the inclusion of a correction for nonparallelism/nonperpendicularity in the sample. [Work was supported in part by the Office of Naval Research.]
RUS investigation of the anisotropic elastic properties of GFRP composites at low temperatures.
Authors: Whitney Timothy M. , Green Robert E.
Published: October 2005

The resonance spectrum of any specimen is dependent on its symmetry, density, geometry, elastic properties, and the boundary conditions. By using specimens with simple known geometry and models including speci- men symmetry, resonance ultrasound spectrosopy can determine the full elastic stiffness tensor to great precision with one measurement. This measurement is fast, taking less than a minute with state-of-the-art instrumentation, making it appropriate for measuring properties as a function of temperature. Parts per million changes in specimen density, geometry, elastic moduli, temperature, and boundary conditions can be detected in carbon fiber reinforced epoxy composite materials with resonance ultrasound spectroscopy. It is important to know the mechanical properties of carbon fiber reinforced epoxy composite materials at low temperatures for underwater, space, and polar applications. The amplitude/frequency resonance spectra of four different lay-ups of AS4/3501-6 carbon fiber reinforced epoxy composite have been measured at 1 °C intervals from −177 °C to 25 °C. The spectra indicate increasing stiffness and decreasing damping with decreasing temperature.

All posters will be on display from 1:00 to 4:00 p.m. To allow contributors an opportunity to see other posters, contributors of odd-numbered papers will be at their posters from 1:00 to 2:30 p.m. and contributors of even-numbered papers will be at their posters from 2:30 to 4:00 p.m.
One, two, many—Judging the number of concurrent talkers.
Authors: Kashino Makio , Hirahara Tatsuya
Published: October 2005

The ability of listeners to judge the number of concurrent talkers was examined. Ten female and 11 male Japanese talkers each recorded 20 familiar Japanese words consisting of four consonant–vowel syllables each. In each trial, a number of different talkers was chosen randomly from the same-sex group, and presented synchronously to four native Japanese listeners, who were asked to judge how many talkers were present. The range of talker numbers was unknown to the listeners. To eliminate cues associated with level, the over-all sound pressure level was varied randomly in each trial, with RMS levels of the individual words equalized. It was found that judgments were nearly perfect for up to two talkers, but deteriorated abruptly for three or more talkers. In the latter case, the number of talkers was underestimated, although estimates increased slightly as the number of talkers increased. Factors that may promote sound source separation, such as lexicality (e.g., forward versus reverse speech) and spatial separation (e.g., single versus multiple loudspeakers), did not affect performance. Understanding a message in the presence of other voices may be different from the judgment of number of talkers; the former requires only the separation into two entities—one and the others.
Anticipatory perception of object pass-by using changing intensity alone: A psychophysiological study.
Authors: Erwin Terri A. , Tassinary Louis G.
Published: October 2005

Prospective information, that is, present conditions of stimulation that are informative about a future state, e.g., the timing and/or location of an impending contact, is required for coordinating acts of interception and avoidance. In the present study, acoustic simulations of passing objects (at different speeds and distances) were produced by modulating the amplitude of a 1-kHz tone in accordance with the inverse square law of acoustic intensity. The simulations were used to explore listeners’ capacity for auditorally anticipating arrival time simply on the basis of intensity change—formulated as a tau variable [see Shaw, McGowan, and Turvey, Ecol. Psychol. 3, 253–261 (1991)]. Subjects indicated either the arrival time of a single passing object or the first arrival within a pair by squeezing a dynamometer. Response accuracy/variability and anticipatory EMG, SCR, and EEG activity were used as indexes to listeners’ ongoing awareness of object position during the simulated approach. Preliminary results indicate highly systematic accuracy and variability, along with the inadequacy of tau as a means of formalizing the relevant prospective information supporting anticipation.
Dichotic temporal order thresholds.
Authors: Pastore Richard E. , Crawley Edward J.
Published: October 2005

Temporal order thresholds (TOT) were measured for dichotically presented stimuli. Earlier research, using diotic or monaural presentation, required subjects to respond to the perceived spectral properties of the earlier onset stimulus. Dichotic presentation provides an opportunity for the subject to respond to ear with earlier onset, pitch with earlier onset, or both. These alternatives allowed two issues to be evaluated: (1) peripheral (changes in neural patterns) versus central coding and (2) the role of pitch processing in response specification. Contrary to arguments that TOT is the result of low level interactions or changes in peripheral coding, all values for responding based on pitch or ear were within the range of previous findings. Thresholds were largest for responding based solely on pitch presumably because temporally greater information is required to specify pitch than ear. In addition, thresholds were smallest when subjects could use a combination of ear and pitch, possibly reflecting a simpler or less uncertain task.