bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of higher-order acoustic nonlinearities in NDE
Authors: Adler Laszlo , Nagy Peter B. , McGowan Paul , Rypien David
Published: October 2005

The acoustoelastic method is a well-established way to obtain third-order elastic constants in bulk materials. Modifications are needed to extend this technique to obtain higher orders, e.g., fourth-order elastic constants, or to increase accuracy to adopt the technique for very thin layers, e.g., adhesive bonds. These higher-order nonlinearities are separated from the stronger first-order nonlinearities (associated with the third-order elastic constants) by the appropriate choice of polarization and harmonic analysis of dynamic acoustoelastic results. It has been shown that inclusion of the fourth-order elastic constants will lead to strength-related mechanical properties of the adhesive bond. [This work was supported by the Center for NDE operated by the Ames Laboratory, USDOE for the Air Force Aeronautical Laboratories/Materials Laboratory under Contract No. SC-89-168 with Iowa State University.]
A comparison of comodulation masking release and profile analysis
Authors: Fantini Deborah A. , Schooneveldt Gregory P. , Moore Brian C. J.
Published: October 2005

Large reductions in signal thresholds may be observed under stimulus conditions in which there is common information in a number of auditory channels or critical bands. In comodulation masking release (CMR) tasks, a reduction in the threshold of a signal in a narrow-band noise occurs when a flanking or cue band of noise is also present, provided that the flanking band has an amplitude envelope which is correlated with that of the masker band. This reduction in threshold occurs in dichotic conditions, where the flanking band is presented in the opposite ear to the signal-plus-masker. In profile analysis (PA), the overall level is randomized from one stimulus to the next. The threshold for detecting an increment in level of a single component is reduced when flanking components equal in amplitude to the pedestal are added. In general, this effect has not been found when the flanking components are presented dichotically. The present work examines the extent of the similarity, and divergence, between CMR and PA. For the PA conditions, a five-component sinusoidal complex was used; its level was varied randomly over a 40-dB range. For the CMR conditions, each of the five components was 100% sinusoidally amplitude modulated at a 10-Hz rate. Two intermediate conditions of PA without the level variation, and CMR with the level variation, were also run. All four conditions were run monaurally and dichotically. A reference condition in which only one masking component was present was also used. For PA conditions when the stimulus level was randomized, thresholds in the monaural and dichotic conditions were 16 and 11 dB lower than in the reference condition, respectively. By contrast, for the CMR conditions, whether the stimulus level was randomized or not, thresholds in the reference, monaural and dichotic conditions differed by little more than 3 dB; i.e., no CMR was observed. Further experiments are now in progress to determine why a CMR was not observed in these conditions.
Basic sensitivity on vowel and consonant continua: A function of phoneme categories
Authors: Schouten Bert , van Hessen Arian
Published: October 2005

The relation between labeling and discrimination of stimuli drawn from a short-vowel and a plosive-consonant continuum was investigated. Stimuli were generated by interpolation between the spectral envelopes (derived with cepstral deconvolution) of naturally spoken syllables. The tasks were phoneme labeling, fixed and roving same-different discrimination with or without feedback, and fixed and roving 2IFC discrimination with feedback. The results indicate that, with natural speech sounds, labeling precedes the discrimination response, even in fixed discrimination, which is supposed to measure basic sensitivity. Equivalence between labeling and discrimination was strongest with consonants, which agrees with the old categorical perception literature. Varying ISI had a small effect on fixed same-different discrimination; at 100 ms, performance was relatively high, and significant category peaks had disappeared; this could suggest basic sensitivity, but labeling performance was even higher. The effect of ISI on 2IFC discrimination was the reverse: a long ISI of 2000 ms improved performance considerably, especially at the category peak. It seems, therefore, that with speech 2IFC is a labeling-oriented task: It improves with time, particularly in a fixed-discrimination paradigm.
Relation between comodulation masking release and auditory grouping
Authors: Hall Joseph W. , Grose John H.
Published: October 2005

CMR was investigated in conditions where some flanking hands were comodulated with the on-signal band, but other flanking bands (“codeviant” bands) were comodulated between themselves, but not with the on-signal band. Past research has indicated that CMR is often substantially reduced when codeviant bands are present. It is possible that the disruptive effects of codeviant bands can be reduced by factors related to auditory grouping. In one condition, 20-Hz-wide comodulated bands were present at 400, 600, 800, 1000, 1200, 1400, and 1600 Hz (1000-Hz signal frequency). When two codeviant bands were added at 900 and 1100 Hz, CMR was reduced from 16 to approximately 4 dB. Progressively more codeviant bands were then added, interspersed with the six comodulated bands. The rationale was that as more codeviant bands were added, they were more likely to be grouped separately from the on-signal band, and their disruptive effects would, therefore, be reduced. A second manipulation was to gate the codeviant bands differently from the comodulated bands: If the codeviant bands are given a unique gating pattern, they should be less likely to be grouped with the comodulated bands. Both of the above manipulations significantly reduced the disruptive effects of codeviant bands. The results suggest that one stage of CMR analysis apparently takes place subsequent to a stage of auditory grouping. [Work supported by the U.S. Air Force, AFOSR.]
Recovery of tongue function for speech and swallowing in partial glossectomy patients
Authors: Hamlet Sandra L. , Patterson Robin , Fleming Susan
Published: October 2005

Most previous research on glossectomy speech has been cross sectional—patients were tested at only one point in time, usually several months or years post surgery. This study of oral cancer patients was designed to provide insight into the development of compensatory articulation and swallowing patterns in the early post surgery and subsequent radiation therapy period. Synchronized videofluoroscopic and acoustical recordings of speech and swallowing were made at specified times during and after cancer treatment. Tongue mobility relative to the jaw was greater post radiation treatment compared to post surgery. Expected co-articulatory variation in second formant frequency of vowels, as a function of consonant context, did not reappear until 6 months post treatment. Tongue activity for the oral phase of swallowing showed similar recovery of differential patterns related to bolus volume. Data on rule-governed subtleties of tongue activity related to details of the speech or swallowing context provide a sensitive measure of reestablishment of naturalness in tongue function.
Automatic alignment of phonetic events with x-ray microbeam articulatory data and the acoustic speech signal
Authors: Greenwald J. H. , Krishnamurthy A. K. , Fujimura O.
Published: October 2005

This paper describes an algorithm for the automatic alignment of phonetic events with x-ray microbeam articulation data and the corresponding acoustic signal. The algorithm uses a two-step procedure similar to that of Nelson [Nelson et al., J. Acoust. Soc. Am. Suppl. 1 63, S32 (1978); Nelson, AT&T Bell Laboratories Internal Rep. (1978)]. The first step locates the phrase boundary in continuous speech, and the second step matches the phonetic segments in each phrase. Articulatory and acoustic events are recognized in continuous speech, and matched to the predicted phonetic events using a dynamic programming technique. The place of articulation and voicing for certain phonemes are also matched with articulatory and acoustic events. The system is presently speaker dependent, and has to be trained to the articulatory data for the particular speaker. [Work supported by Ohio State University Speech and Heating Department.]
Acoustic navigation for a large aperture array
Authors: Sotirin B. J.
Published: October 2005

The acoustic navigation system for a large aperture (900 m) vertical array and the resulting data, describing the motion of the array and research platform FLIP during a 20-day deployment in the NE Pacific, are presented. Acoustic navigation data are acquired by detecting the high-frequency signals emitted by near bottom transponders. Recorded travel times are converted to xyz positions by a nonlinear least-squares approach that adjusts the transponder, FLIP, and the array positions, minimizing the rms error. Simulation results highlight error sensitivities. The movement of FLIP, although constrained by a three-point moor, exhibits a wind-driven component and a clockwise semidiurnal tidal component with horizontal displacements in excess of 300 m. Suspended vertically from FLIP under tension, the array has a damped response to tidal and internal wave forces. [Work supported by ONT.]
Time domain solutions for scattering from objects in a waveguide
Authors: Ellis Paul , Werby M. F.
Published: October 2005

Calculations that describe scattering from an object in a waveguide in the frequency domain are very time consuming. For the time domain it can be orders of magnitude more expensive both in time and storage than for the frequency domain, rendering such calculations impractical unless a supercomputer can be used. The solution of scattering from an object for a realistic target and waveguide using the Cray 2 computer (a 528-Megaword, 4.1-ns machine) at the Minnesota Supercomputer Institute is discussed. The methods employed as well as results will be presented.
Study of acoustic transmission loss in sediments at low frequencies using parametric acoustic arrays
Authors: Bindal V. N. , Saksena T. K. , Jain S. K. , Gupta Recta , Santoshi D. N.
Published: October 2005

Investigations have been carried out on the acoustic transmission loss in clay, sand, and gravel in the frequency range 6–10 kHz. Parametric acoustic arrays have been used for this study and have been generated using amplitude modulation of a primary transducer of frequency about 300 kHz in which the carrier was suppressed. Source level and beam width of the parametric signal have been ∼ 155 dB re: |μPa/m2 and 3.6°, respectively. Experiments have been conducted in the laboratory taking the sediment in a rectangular container of dimensions 0.7×0.49×0.6 m3. The acoustic transmission loss using parametric arrays has been compared with the measured loss with a nonparametric source. The results show a dependence of transmission loss on the particle size and are discussed in the light of previous studies.
Transient response of a fluid-filled borehole due to the passage of transient elastic waves
Authors: Chang C. , Chang S. K.
Published: October 2005

The interaction of transient elastic waves with a fluid-filled borehole is investigated both experimentally and theoretically. The elastic waves incident from various angles are partially scattered by the borehole, while an acoustic wave field is introduced in the borehole fluid. Experiments were conducted in a solid block with a circular borehole inside. The transient elastic waves were generated by using either a simulated acoustic emission source or an ultrasonic transducer. The acoustic pressure in the borehole was measured by a commercial PZT hydrophone and by a home-made PVDF hydrophone. The effect of the borehole on the elastic waves is identified by comparing the measured acoustic responses with the undistorted incident pulse, calculated by the generalized ray theory without the borehole. The theory of plane wave scattering by a borehole is used to compare with the experimental data. The transient results from both the experiments and the borehole theory agree with each other very well, and they both exhibit resonances due to the multiple reflections inside the borehole fluid.
Effects of a silent temporal interval on discriminability of bursts of reproducible noise
Authors: Fallon Susan M. , Robinson Donald E.
Published: October 2005

A same-different psychophysical method was used to examine the discriminability of bursts of reproducible noise. Bursts in a pair were identical on “same” trials. On “different” trials, bursts were identical except for τ ms of independent noise located at either the beginning, middle, or end of the burst pairs. Fallon and Robinson [J. Acoust. Soc. Am. Suppl. 1 78, S46 (1985)] showed that discriminability depends on the temporal position and proportional duration of the independent noise. The present experiments examined whether a silent interval placed either immediately prior to or following the independent noise improves discriminability. Results showed that a silent interval only improved discriminability if it replaced a portion of the noise common to the pairs of bursts. In this experiment, a brief burst of common noise temporally separated from the independent noise by 90–120 ms caused a large decrement in performance. These data suggest that interactions occurring after such a long silent interval are unlikely to be generated peripherally. [Work supported by AFOSR.]
Auditory temporal acuity for dynamic signals
Authors: Feth Lawrence L. , Neill Mary E. , Krishnamurthy Ashok
Published: October 2005

Previous reports of auditory temporal acuity have generally used static, rather than dynamic, signals; that is, the charactersitics of the signal did not change within its brief duration. Temporal acuity is defined as in Green [Psychol. Rev. 78, 540–551 (1971)]: the shortest time interval within which a listener cannot detect a change in the sound. Auditory temporal acuity is determined using frequency-modulated (FM) sinusoids. The two FM signals used in each block of trial always began at the same initial frequency and moved to the same final frequency. Only the trajectory, the path from initial to final frequency, differed. One trajectory, the glide, moved linearly from initial to final freqency; the other proceeded in a series of discrete steps. As the number of steps increased, the size and duration of an individual step decreased, and the multiple-stepped transition more closely approximated the glide. Four well-practiced listeners were asked to identify the interval containing the glide in a 2-Q, 2AFC task. Frequency transitions of 100-, 200-, and 403-Hz durations of 25, 50, and 100 ms were centered on octave frequencies from 250 to 4 kHz. Signals were presented at 50 dB SL for each subject. Results for the four listeners were remarkably consistent, with the 75% discrimination point falling at 7 to 10 ms for all conditions except for signals centered at 4 kHz. Poorer performance at 4 kHz may reflect the loss of synchrony in the frequency region; however, there are some difficulties with that explanation. [Work supported by a grant from AFOSR.]
Power spectra of some modes of speech
Authors: Nábělek Igor V.
Published: October 2005

The data to be reported represent an extension of the previous study “A comparison of spectra of loud and whispered speech” [Nábělek and Maroonroge, J. Acoust. Soc. Am. Suppl. 1 75, S83 (1984)]. Power spectra were determined for three modes of running speech: phonated conversational speech, phonated monotonous speech, and whispered speech. The average spectrum of the phonated conversational speech had a broad maximum around 300 Hz; the spectra of the phonated monotonous speech had pronounced peaks at the fundamental frequency and its harmonics. The average spectrum of the whispered speech was rather flat at low frequencies, and it was similar to the spectrum of the phonated speech at frequencies above 2000 Hz. The implications of differences between the spectra for testing will be discussed.
The construction of dynamic effective medium theories (EMT) for inhomogeneous fluid or elastic continua
Authors: Gaunaurd G. C.
Published: October 2005

A deterministic technique is described that predicts the dynamic (i.e., frequency-dependent) effective properties of inhomogeneous media. Situations are considered in which a host medium sustaining a distribution of spherical inhomogeneities is either fluid or solid. In the Rayleigh region (viz., a/λ < 1) in which most effective medium theories (EMTs) hold, inhomogeneities of any shape can be assumed spherical without much error. However, assuming them to be penetrable implies that they realistically admit interior fields, which are coupled to the exterior ones by stress and displacement boundary conditions. The outcome of dynamic EMTs is a set of expressions to predict the frequency dependence of the effective (sound) wave speed c̄eff, and the effective (sound) wave attenuation ᾱeff in the mixture. These quantities emerge from the real and imaginary parts of the effective wavenumber k̄eff, which are connected by Kramers-Kronig type relations, as has been discussed by Dr. Beltzer. An important consideration for the practical usefulness of an EMT is its simplicity. Often, the resulting predictive expressions are so cumbersome that they can only be evaluated by means of quite formidable computer codes. The principal EMT to the discussed here, yields closed-form simple predictive expressions for c̄eff and ᾱeff, which, in many instances, are valid over significantly broad frequency bands. These expressions reduce to (and contain) almost all existing earlier results for static (f→0) cases. The (present form of this) EMT is constructed by exploiting the presence of the monopole resonance of the inhomogeneities, and thus it works best in the cases in which this resonance is dominant. This EMT has to be further refined to account for cases where the dipole resonance is dominant. In this regard, Dr. Martinez, in a later lecture, will discuss an approach to more accurately deal with heavy/rigid inclusions in a rubberlike matrix. [Work supported by NSWC and ONR.]
Pulse propagation in irregularly heterogeneous waveguides—Some model calculations
Authors: McCoy John J. , Tanzosh John
Published: October 2005

Numerical simulations are presented of the propagation of pulses through a series of idealized one-dimensional waveguides, both isolated and coupled. The results are discussed in the context of determining what aspects lead to predictive modeling in terms of statistical moments; what ergodicities can be argued to allow predictions for an ensemble to apply to a single manifestation of the ensemble; what physics need to be accommodated in mean field formulations; what are the necessary structures of these formulations; etc. The emphasis of the simulations is to illustrate phenomena, as distinct from quantitatively reproducing expected results of physical experiments for specific application. [Work supported by ONR.]
Precision measurement of violin string modes
Authors: Ricca Bernard , Weinreich Gabriel , Michael Nicholas R.
Published: October 2005

Following a suggestion of Benade (private communication) that small inharmonicities in the mode frequencies of a string may have important effects on its bowing response, a method has been developed for precisely measuring the (complex) normal frequencies and polarizations of a string as mounted on a violin, with the aim of determining, among other things, whether the violin maker's adjustments of bridge and soundpost are systematically reflected in the string's inharmonicity. The procedure, which uses acoustic excitation and a two-dimensional photoelectric detector of string motion, is based on earlier work [E. B. Arnold and G. Weinreich, J. Acoust. Soc. Am. 72, 1739 (1982)] but uses a higher frequency resolution (0.125 Hz) and a least-squares fitting of the resonant string response. Some results on the shift of string frequencies due to controlled loading of the bridge will be presented. [Work supported by NSF.]
The development of musical tuning perception from infancy to adulthood
Authors: Lynch Michael P. , Eilers Rebecca E. , Oller D. Kimbrough , Wilson Paul
Published: October 2005

Three prominent hypotheses were evaluated by testing Western infants' and adults' abilities to detect mistunings in melodies based on native Western and non-native Javanese scales. The “innateness hypothesis” of speech perception applied to music perception suggests that infants are born with an equipotential to perceive the scales of any culture. The “naturalness hypothesis” of auditory perception suggests that the ear is best suited for processing the small-integer frequency ratios that comprise Western scales. Finally, the “perceptual loss hypothesis” of speech perception allied to music perception proposes that the ability to perceive non-native scales is reduced and the ability to perceive native scales is maintained from infancy to adulthood. In support of the innateness hypothesis and in contradiction of the naturalness hypothesis, 5- to 7-month-old infants did not possess a perceptual bias for either Western or Javanese scales. The perceptual loss hypothesis was weakened because, although adults possessed a perceptual bias for the Western over the Javanese scales, adults' perception of both these scale types was better than that of infants. [Work supported by the American Psychological Association.]
Intonation and syntax: Preferred co-occurrences between pitch contour and sentence structure
Authors: de Zitter Aart , Collier René
Published: October 2005

Melodic models, also called “intonation grammars,” specify the perceptually relevant properties of pitch movements and indicate which sequences of them constitute well-formed pitch contours [N. Willems, R. Collier, and Y. 't Hart, J. Acoust. Soc. Am. 84, 1250–1261 (1988)]. It appears that for each basic intonation pattern several contour variants can be generated that sound equally acceptable from a purely melodic point of view. However, not every contour is compatible with just any sentence. Indeed, in many cases the choices that speakers make appear to be far from random. Rather, they are governed by syntactic, semantic, and pragmatic considerations. The present paper concentrates on syntactic variables such as the degree of structural cohesion between pitch-accented words or the depth of the syntactic boundary between phrasal constituents. Experiments will be discussed in which syntactic variables appear to influence the preference of the speaker or the listener for particular pitch contours. It will be examined to what extent these results are relevant for improving synthetic intonation in text-to-speech systems.
The detection of in-phase and out-of-phase tones presented either randomly intermixed in the same blocks of trials or in separate blocks of trials
Authors: Emmerich David S. , Brown William S. , Thorns James B.
Published: October 2005

When signals that are binaurally in phase are presented in a background of in-phase noise, they are generally considered to be detected by means of monaural processing. However, when out-of-phase signals are presented in the same background of in-phase noise, binaural processing is involved. One question addressed in the present research is whether subjects are able to process such monaural and binaural signals as efficiently when they are randomly intermixed within the same blocks of trials of a single-interval yes-no procedure, as when they are presented in separate blocks of trials. As in other experiments involving stimulus uncertainty, evidence was found of some impairment associated with listening for monaural and binaural signals simultaneously. Response latencies were also examined in order to gain additional information about stimulus processing. Latency-based operating characteristics were derived using the same procedure employed by Emmerich et al. [Percept. Psychophys. 11, 65–72 (1972)], among others, and compared for monaural and binaural listening conditions.
The potential role of acoustic cavitation in medial ultrasound bioeffects
Authors: Crum L. A. , Roy R. A. , Church C. C.
Published: October 2005

Ultrasound is used in a variety of modalities in medicine. Some of these uses are: therapeutic—in which ultrasound is intended to have a (beneficial) biological effect; mechanical—in which vibrating tools are used as surgical scalpels, as dental scalers, etc.; diagnostic—in which clinical evaluations are made of internal organs and body conditions; clinical—in which high-intensity shock waves are used to comminute undesirable concretions such as renal or biliary calculi. For all these modalities, when their waveforms and typical acoustic intensities are reproduced in aqueous liquids in the laboratory, acoustic cavitation normally occurs. Since cavitations can also result in severe mechanical damage to objects in its vicinity, its presence in vivo is therefore to be avoided. This group has been active for some years in the study of cavitation produced by medical ultrasound devices and reports will be presented on various aspects of these investigations. [Work supported in part by NIH Grant No. 2 R01CA 39374-04 A1, and by the Office of Naval Research.]
Implications of gas body activation for medical ultrasonics
Authors: Miller Douglas L.
Published: October 2005

A stabilized body of gas in a biological medium can be directly activated (set into oscillation) by megahertz-frequency ultrasound, and cause nonthermal bioeffects at levels below the cavitation threshold. This phenomenon has been studied in plant tissue with intercellular gas-filled channels, in insect tissue with gas-filled tracheal systems, and in cell suspensions provided with gas trapped in hydrophobic micropores. The highly localized oscillation leads to the gathering of particles by radiation forces and to damaging shear stresses from acoustic microstreaming flow. In tissues, the bioeffects seem to have discernible thresholds and to depend on the temporal-peak intensity of exposure. In cell suspensions, for which effects involve collection of cells, a dependence on the square of the temporal-average intensity is discernible. In these model systems, significant effects can be observed with exposure parameters similar to those encountered in diagnostic medical applications. Furthermore, studies of decompression sickness and cavitation indicate that stable gas bodies may sometimes exist in mammalian tissue. Although further study of possible hazards is clearly needed, the existence of even this potential risk may justify concern about frivolous exposures with medical devices. [Work supported by PHS grant CA42947 awarded by the National Institutes of Health.]
Electroacoustical simulation of listening room acoustics for project ARCHIMEDES
Authors: Bech Søren
Published: October 2005

ARCHIMEDES is a psychoacoustics research project, funded under the European EUREKA scheme. Three partners share the work involved: The Acoustics Laboratory of The Technical University of Denmark; Bang and Olufsen of Denmark; and KEF Electronics of England. Its primary object is to quantify the influence of listening room acoustics on the timbre of reproduced sound. For simulation of the acoustics of a standard listening room, an electroacoustic setup has been built in an anechoic chamber. The setup is based on a computer model of the listening room, and it consists of a number of loudspeakers positioned on an imaginary sphere surrounding the position of the test subject. The setup has been designed for the highest degree of flexibility. This includes the possibility of simulation of directivity characteristics of normal domestic loudspeakers and absorption coefficients of the surfaces of the listening room. This paper is a presentation of the system, with special emphasis on the psychoacoustical background of the design. This will include a discussion of choice of experimental procedure, test stimuli, and test subjects as well as purpose built loudspeakers and the DSP system.
RODS—An advanced approach to electronic reverberation enhancement
Authors: Barnett Peter W.
Published: October 2005

This paper will briefly review the recent history of reverberation enhancement and then examine the processes involved in the development of the RODS (Reverberation-on-Demand System) concept. The theory and implementation of the RODS concept will be explained, followed by examples and results of recent installations.
Weaker sonic booms may be considerably more quiet
Authors: Pierce Allan D.
Published: October 2005

Present indications are that realistic designs of civilian supersonic aircraft can be achieved so that the sonic boom at the ground has substantially smaller pressure jumps (shocks) than was the case for previous designs and for the Concorde. Unknown as yet is the extent to which this achievement may increase public acceptability to the intrusion of occasional sonic boom events. The present paper reviews physical acoustics research that may pertain to this question, and examines the magnitude and possible definitions of rise times of sonic boom shocks. The detailed pressure profile at a shock determines the high-frequency content of the boom and affects the perceived loudness and the startle effect, with the rise time being a rough descriptor of this high-frequency content. Earlier theoretical considerations had suggested that the rise time, on the average, should be inversely proportional to the shock jump. Molecular relaxation effects, however, are now known to play a major role and lead to the intriguing prediction that rise times for shock jumps below approximately 50 Pa are substantially longer than one would extrapolate from measured rise times of stronger shocks using the simple inverse proportionality relation. The extent and nature of atmospheric turbulence effects are still incompletely understood and stimulate further research. [Work supported by NASA-LRC and by the William E. Leonhard endowment to Pennsylvania State University.]
Noise from low-altitude military flying
Authors: Plotkin Kenneth J. , Molino John A.
Published: October 2005

Military air tactics rely on increasing use of high-speed low-altitude penetration techniques. Training for this type of operation can take place in specially designated low-altitude military operation areas (MOAs) or along military training routes (MTRs). Environmental assessment of noise from these operations has become an important factor in the design of these special use airspaces. The noise environment is different from commonly studied situations such as airport or highway noise in urban/suburban areas, and it is not obvious that the usual Ldn analysis is appropriate. Individual events are loud (maximum levels in the 100–115 dBA range) and short (10 dB down durations of a few seconds). Noise events are infrequent (typically less than 3 or 4 per day on busy routes) and occur at random times. These operations also take place in quiet rural areas. A discussion is presented of the nature of these operations and the resultant noise environment. This noise is contrasted with well-understood noise environments. An interim noise metric, Ldnmr (monthly average, onset rate corrected Ldn), developed for the U. S. Air Force is presented. A comprehensive research plan to test Ldnmr, or replace it with a more appropriate metric, is discussed.
Evaluation and verification of bottom acoustic reverberation statistics predicted by the point scattering model
Authors: Alexandrou D. , Haralabus G. , de Moustier C.
Published: October 2005

The point scattering model offers a parametrization of the reverberation envelope probability density function (pdf) in terms of the average number of scatterers contributing to the return and the presence of a coherent component in the received process. Computer simulations were used to verify model predictions and to evaluate their usefulness in the context of sea floor classification. Central to the verification strategy was the successful solution of the inverse problem based on synthetic reverberation data. The average number of scatterers was determined from estimates of the kurtosis of the instantaneous reverberation pdf. The magnitude of a coherent component embedded in the scattered return was recovered from envelope histograms with the assistance of the Kolmogorov goodness-of-fit test. Following the verification study, the model was perturbed by introducing clustered and ordered distributions of scatterers in addition to the standard Poisson. The initial results indicate that the reverberation envelope pdf differs significantly for the three scatterer distributions. The clustered distribution led to a rapid increase in kurtosis, while the ordered distribution displayed evidence of intermittent coherent scattering. The usefulness of this parametrization was further tested with real reverberation data representing several distinct seafloor regimes. [Research funded by ONR.]
Angular dependence of seafloor acoustic backscatter at 12 kHz
Authors: de Moustier C. , Alexandrou D.
Published: October 2005

The angular dependence of seafloor acoustic backscatter measured with a 12-kHz multi-narrow-beam echo sounder over a variety of seafloors, ranging in depth from 500 to 5000 m, has been determined for incidence angles from 0 to 25 deg. The acoustic data consist of quadrature samples of the beamformed echoes received on each of the sixteen 2.66-deg beams of a Sea Bearn echo sounder. These data are subjected to adaptive noise canceling for sidelobe interference rejection and to beam-to-beam “decorrelation” to ensure that the returns are separated in angle with minimal cross talk between adjacent beams. The measurements are then corrected for geometric effects, taking into account the ensonified area for each beam, which varies as a function of the ship's roll and bottom slopes. It was found that apparent bottom slopes of less than 2 deg in the athwartships direction are noticeable in the data and must be compensated for. For lack of system calibration, the data are presented as relative mean energy levels in 1-deg bins from 0- to about 25-deg incidence. These results are compared with the results era REVGEN computer simulation which faithfully reproduced the acoustic geometry of the Sea Beam system and generated scattered returns devoid of a specular component. Results are discussed based on geometric and physical arguments, and the ability to differentiate seafloor types using such angular dependence functions as assessed. [Research funded by ONR.]
Application of vector intensity techniques for the acoustical characterization of a baroque-style Italian theater
Authors: Stanzial Domenico , Carletti E. , Vecchi I. , Fuschini A.
Published: October 2005

Results concerning acoustical measurements carried out in the Municipal Theater of Ferrara, built in 1790, are here presented. Recent restoration works replaced the original wooden stage. A model, which describes the enclosed space as a retroactive linear system, has been developed to characterize rooms acoustics. Modifications of the acoustic field, induced by the new stage, were measured by means of the following objective tests: evaluation of the theater transfer function having related input and output, respectively, defined by the free-field acoustic power of a reference source and the measured power emitted by the same source placed on the stage surface; mapping of isointensity levels over the coupling area between stage and hall (proscenium plane); evaluation of acoustic-intensity-based transfer functions over a grid in the proscenium plane. A further description of the theater acoustics was obtained by intensity vector measurements over three parallel grids in the proscenium. Results of this additional characterization are presented as graphic views of acoustic intensity flow lines.
Separation of total transfer function phase into propagation and reverberant components
Authors: Liu Lan , Lyon Richard H.
Published: October 2005

Previously reported theory of phase decomposition used the complex cepstrum to extract the all-pass phase from the total phase of acoustical space transfer functions. The all-pass phase is associated with the reverberant properties of two- and three-dimensional spaces. The dereverberation of acoustical signals in such spaces can be accomplished by this separation. This paper describes the results of some recent experimental studies of sound propagation in one-, two-, and three-dimensional spaces. A comparison of the expected and observed components of reverberant and propagation phase, with the results from these experiments, is presented.
Analysis and synthesis of six voice qualities
Authors: Ananthapadmanabha T. V. , Estill Jo
Published: October 2005

This is a preliminary study reporting on the acoustic analysis and synthesis of six selected voice qualities; speech, falsetto, low-larynx, twang, belting, and opera. The purpose of this investigation is to test the ability of the source-filter model to synthesize this wide range of voice qualities. Five vowels, /i/,/e/,/a/,/o/, and /u/, in six voice qualities spoken by a trained female speaker were recorded in a treated sound booth, allowing SPL and F0 to free vary with a normal decay at the end of each token. These recorded signals were digitized directly onto a computer. Inverse filtering of vowel sounds was performed using the linear prediction technique. Parameters of voice source were extracted from the inverse filtered signal. Also, the spectral envelopes of the vowels were obtained. The six voice qualities were synthesized and compared with the original recording. Informal listening tests indicated little difference between the original and the synthesized tokens, thereby confirming the analysis procedure. To study the relative contributions of source and filter components, vowels were synthesized using the vocal tract transfer function appropriate for each quality but using an arbitrary voice source. The voice source was varied in two ways; (i) keeping the amplitude natural but pulse shape fixed and (ii) keeping both the amplitude and shape fixed. The differences in voice qualities were still distinguishable. Perceptually, these data seem to indicate that the spectral envelope is sufficient to synthesize these voice qualities. Physiologically, it would appear that glottal pulse shape is not significant. However, the spectral envelope may still contain components of the source such as subglottal coupling, spectral slope, and/or the effect of the laryngeal resonator on the vocal cavity transfer function. A demonstration tape will be presented.
Probe microphone techniques for determining exposure to noise
Authors: Killion Mead C.
Published: October 2005

Traditional dosimeter measures, using a microphone in the sound field, provide little information about the actual noise exposure experienced by a subject wearing earplugs, earmuffs, earphones (traditional or insert), or someone exposed to a highly directional or local noise source. In these instances, the noise at the eardrum would appear to be a more useful measure, but cannot be directly compared to traditional damage risk criteria because the latter are based on measurements in a diffuse sound field. If a simple bridged-T filter network [Killion, J. Audio Eng. Soc. 27, 13–16 (1979)] correcting for the transfer function between the diffuse field and the eardrum is interposed between a flat-frequency-response probe microphone and a dosimeter, the resulting dosimeter indication can be compared directly to traditional damage risk criteria. Techniques for minimizing the potential errors in such measurements will be discussed.
A spatial sound processor for headphone and loudspeaker reproduction
Authors: Martens William L. , Kendall Gary S. , Wilde Martin D.
Published: October 2005

A spatial sound processor for stereo headphone and loudspeaker reproduction is described that can position sound elements within a three-dimensional reverberant space surrounding the listener. Spatial motion of sound sources in three dimensions is created by dynamic filtering based on head-related transfer functions. Additional filters and delay lines capture air absorption and Doppler shifting as the propagation time is manipulated for both direct and indirect sound. The spatiotemporal distribution of early reflections is captured for a given source/listener orientation: The gain, delay, and directional filtering of simulated reflections are responsive to changes in the specified position and orientation of the sound source and the listener's head in the simulated environment. The spatial processor can be used for headphone reproduction using a head-tracking device, and can also be used in more typical reproduction settings such as living rooms with stereo loudspeakers. In the latter case, additional processing is employed to stabilize the stereo image and produce a spatially diffuse reverberant surround effect over a wide range of listening positions.
On the model order for the identification of acoustical systems
Authors: Koizumi Nobuo , Lyon Richard H.
Published: October 2005

The pole/zero model and the finite impulse response (FIR) model are used as system models for the identification of unknown acoustical systems. The size of the model is particularly important in discrete-time implementation as it determines the convergence rate of adaptation and capacity of real-time processing. The order of the pole/zero model is related to modal distribution of systems while the order of the FIR model depends on its damping factor. Effective orders of both models are estimated from the statistical properties of acoustical systems. In a three-dimensional enclosure, its volume and reverberation time are used for estimation. It is shown that, when modal density of the system is low, such as in a small enclosure, and frequency range is narrow, pole/zero modeling can greatly reduce the model order. [Work supported by NTT Human Interface Laboratories, Tokyo 180, Japan.]
The aircraft noise-induced permanent threshold shift
Authors: Yong-xiang Wu , Bing-guang Wang , Xin-yu Wang
Published: October 2005

The hearing of 410 groundcrew who had worked under 100–130 dB(A) aircraft noise was measured. The groundcrew were divided into four groups by the length of service: less than 5 years, 5–9 years, 10–14 years, and 15–20 years. Their audiograms were taken with a Kamplex audiometer in a soundproof mobile cabin, in which background noise was 23–25 dB(A). One-hundred and forty seven military men of comparable age who had not been exposed to excessive noise were selected as a control group. Their audiograms were taken in the same way. The results indicated that the hearing injury was an actual menace to the groundcrew. Among them the high-frequency hearing loss and the noise deafness made up 46.1% and 6.1%, respectively. Compared with the control group of the same age, the differences of the hearing average value of each frequency were significant. Their hearing injury was aggravated with the length of service. The high-frequency hearing losses of the four groups, less than 5 years, 5–9 years, 10–14 years, and 15–20 years, were 32.7%, 47.3%, 54.4%, and 67.3%, respectively. In order to prevent hearing damage, the groundcrew ought to wear ear protectors and the ground noise suppressors should be used when the aircraft engine is operating. It was discovered that the “V”-shaped depression was not at 4 kHz but at 6 kHz in 410 groundcrew. There were similar phenomena in domestic and foreign literatures. The former views concerning the pathogenesis of the “4-kHz depression,” therefore, is open to question. This is a quite interesting subject that warrants further study.
Comparisons of between- and within-subject variability in repeated-measures auditory brain-stem responses (ABRs) in 10- to 12-year-old children
Authors: Oyler Robert F. , Lauter Judith L.
Published: October 2005

In reports to this Society, and in various publications [J. L. Lauter and R. L. Loomis, Scand Audiol. 15, 167–172 (1986); 17, 87–92 (1988)], results of repeated-measures ABR testing in young adults have been described, indicating that the variability of peak parameters, such as latency and amplitude, provides information that absolute values of these parameters do not: contrasts in between- versus within-subject consistency, and by ear of stimulation. Nine 10- to 12-year-old boys were tested in four biweekly sessions, with five ABR waveforms collected in each session for monaural right, monaural left, and binaural clicks. Relative variability measures of ABR latencies reveal adultlike patterns based on nonadult values: (1) contrast in between- versus within-subject consistency; (2) peak differences; and (3) ear differences. There are also differences in within- versus between-session consistency. Preliminary comparisons with results of similar testing in 5- to 7-year-old children [J. M. Lord-Maes and J. L. Lauter, J. Acoust. Soc. Am. Suppl. 1 85, S38 (1989)] and adults suggest that ABR variability may be sensitive to auditory-system developmental changes that continue long after ABR absolute peak latencies have achieved adult values. [Work supported in part by AFOSR.]
Dennis Klatt's contribution to automatic speech recognition
Authors: Zue Victor W.
Published: October 2005

Over the past 20 years, Dennis Klatt has made enormous contributions to the field of automatic speech recognition through his research, writing, and student supervision. In the early 70's, he served as a member of the steering committee of the ARPA Speech Understanding Research (SUR) program, providing leadership and guidance to the research community. He also participated actively in speech recognition research, first performing a set of spectrogram reading experiments assessing the role of various sources of knowledge, and later investigating the use of synthesis-by-rule techniques for word verification. Out of this involvement with the ARPA-SUR program came the landmark paper reviewing its technical achievement. as well as several publications describing his own proposals, LAFS and SCRIBER, for human and machine speech recognition. Over the past 10 years, Dennis directed his attention to the design of signal representation front-ends, as well as the investigation of perceptually motivated distance metrics in order to implement his speech recognition models. This talk pays tribute to Dennis's incredibly active research life by examining the legacy he left behind in speech recognition.
Stress shift as the placement of phrase-level pitch markers
Authors: Shattuck-Hufnagel Stefanie
Published: October 2005

The F0 contours produced by the text-to-speech conversion program Klatttalk [D. H. Klatt, J. Acoust. Soc. Am. 82, 737–793 (1987)] are based on a translation [S. Maeda, RLE-QPR 114, 193–211 (1974)] for American English of the “hat pattern” approach developed for Dutch [J. 't Hart and A. Cohen, J. Phon. 1, 309–327 (1973)]; this approach is similar to an earlier description by Mattingly [I. G. Mattingly, Supplement to Haskins Laboratory Status Report on Speech Research, 1–223 (1968)]. One question that arises for this view of F0 patterns is how might it deal with the phenomenon of “stress shift”: For some speakers, the prosodic prominence on the main-stress syllable of words like “thirteen” and “Mississippi” is perceived to move to an earlier syllable when these words appear in phrases like “thirteen men” and “Mississippi mud.” This paper will report pitch and duration measurements designed to evaluate the hypothesis that at least some aspects of the stress shift phenomenon can be described as the simple placement of the onset rise of a hat pattern on an early syllable of the prosodic phrase.