bluuebunny/crossref_metadata_2025 huggingface dataset:
A simplified approach to a nonlinear loudspeaker modeling
Authors: Geddes Earl
Published: July 2002

Exact solutions of the nonlinear equations for a loudspeaker are extremely difficult to solve as they involve Volterra series expansions and higher-order system functions and impulse responses [A. R. Kaiser et al., J. Audio Eng. Soc. 35, 421–433]. Indeed, these complex methods are required for exact system simulations, however, they can be greatly simplified with a reasonable assumption about the system. By assuming that the distortion (or nonlinearity) is not so large that it causes an excessive amount of distortion, say about 20% THD, a vastly simplified approach can be developed. It is not always the case that this near-linear assumption can be made, but clearly, it should be accurate for higher performance units. This presentation will show how to use an algebra processor (Maple) to develop these simplified predictions given the nonlinearities of the parameters. These equations will then be used to show the effect that various loudspeaker enclosure designs have on the distortion of a given (typical) loudspeaker using a commercially available software package written by the author.
Measurement of direct radiation from violin excited by force hammer impact at bridge
Authors: Bailey Machele , Bissinger George
Published: July 2002

A violin suspended inside a small anechoic chamber was impacted at the bridge with a small force hammer. A rotatable, semicircular, equispaced seven-microphone array was used to measure the radiation in a 0–2 kHz range over a sphere of radius 30 cm (in the near field (r<l) region for f<1100 Hz) at 15° intervals (except in the neck-fingerboard region). The input-force-normalized microphone spectra were then analyzed to separate the contributions from each violin normal mode. On animation, most of the higher-frequency radiation patterns clearly showed apparent ‘‘phasiness’’ among portions of the radiation patterns, an effect primarily related to near-field effects and not the bridge impulse propagation delay through the violin corpus. The measured 3-D radiation patterns for each mode compared well with those calculated with a boundary element program using as input normal mode vibrational data from a prior modal analysis for this violin.
Important violin resonance frequencies
Authors: Rodgers Oliver E.
Published: July 2002

Experimental determination of the natural frequencies and nodal line patterns of those modes which produce sound was made of a test violin which had previously been analyzed by George Bissinger using an experimental modal analysis system [J. Acoust. Soc. Am. 97, 3154–3164 (1995)]. Excitation of the test violin was done by bowing the instrument and the analysis system was the CONQT software previously used by the author. Nodal lines were defined approximately with a small microphone which was held very closely to the plate surface to seek lines of minimum response. Comparison with the Bissinger results points out the very few vibration modes in the first 1000 Hz which contribute to the overall tone of the instrument. These modes are found among those displayed in Bissinger’s work. Only two modes of the air cavity and four modes of the gross mechanical system are important in this frequency range. The CONQT data suggest that tone quality is determined strongly by the five to seven prominent higher modes, which are complex motions of small areas of the plates, and/or by the ability of the lower modes to transmit sound at off-peak frequencies.
Effects of phonotactic probability on segmentation of words in continuous speech
Authors: Gaygen Daniel E. , Luce Paul A.
Published: July 2002

At the last meeting of the Society, evidence was presented regarding the role of phonotactic probability in the segmentation of spoken words in continuous speech. Results of further studies examining this issue will be presented. Participants made speeded word detection responses to sequences of spoken stimuli composed of target words preceded and followed by nonwords (i.e., NONWORD–TARGET WORD–NONWORD). Speed and accuracy of detection were examined as a function of the nonword contexts of the target words. In particular, probabilities of segmental transitions from the nonword contexts to the target words were manipulated: Pairs of segments composed of the last segment of the preceding nonword and the first segment of the target word, as well as pairs composed of the last segment of the target word and the first segment of the following nonword, were varied in terms of intraword transition probability (HIGH and NONE) and position specific segment probability (HIGH and LOW). Only CC transitions were used. Both spliced and coarticulated stimuli were used. The implications of our results for the use of phonotactic probabilities in the identification of words in fluent speech will be discussed.
Modeling the propagation of sound through a turbulent atmosphere
Authors: Blanc-Benon Ph. , Juvé D.
Published: July 2002

Recent advances in the numerical techniques and physical models used in sound propagation codes for the atmosphere have greatly improved the correspondence between calculated and measured fields. In particular, incorporating models of atmospheric turbulence have provided major advances. In this paper, an approach to turbulence modeling is described which the authors have developed in the last few years. The turbulence is represented as a superposition of a limited number of random Fourier modes and the acoustic waves are propagated through each individual realization of this field using a wide angle parabolic equation. Statistical results are obtained through ensemble averaging. Illustrations will be given for both line of sight propagation and for propagation into a refractive shadow zone. The influence of the physical model (vectorial versus scalar and Gaussian versus inertial) on the predicted sound field will be discussed. Extensions to time-domain analyses will also be considered.
Underwater acoustic communication over doubly spread channels
Authors: Eggen Trym H. , Preisig James C.
Published: July 2002

Acoustic communication in the ocean with carrier frequency in the range 5–50 kHz has been performed in both deep and shallow water, and the communication channels can be sorted according to their time and frequency dispersion. Some of the underwater communication channels are significantly spread in both frequency and time; thus they are doubly spread channels. Scattering function estimates computed from real data of different doubly spread channels are presented, and physical scenarios that would produce the different channels are identified by simulations using ray trace and time variant FIR filters. The frequency dispersion depends in particular on relative speed between the transmitter and channel scatterers, or between transmitter and receiver for direct paths, and the eigenrays of some of the physical scenarios can have significantly different Doppler spreads. Current receivers are unable to establish reliable communication over such channels. A new receiver is proposed which can successfully demodulate signals which have propagated through some of the doubly spread channels with multiple Doppler spreads. The receiver makes use of filter taps spaced in both the delay and the Doppler dimensions. Its capabilities and limitations are demonstrated on both real and simulated data.
Environmentallly adaptive signal processing
Authors: Sibul Leon H. , Dixon Teresa L.
Published: July 2002

To achieve required system performance under difficult propagation and reverbaration conditions, signal processing systems must be environmentally adaptive. This paper uses results from statistical signal processing and wavelet transform theory to develop an estimator-correlator (EC) approach to environmental adaptivity. The EC is an optimum (in the maximum likelihood sense) detector and estimator that incorporates propagation and interference (reverberation and ambient noise) models as an essential part of its formulation. It is a doubly adaptive processor because it uses propagation models and on-line adaptation to determine conditional mean estimates of the full-field replicas that it correlates with optimally/adaptively filtered received data. The EC concept is applicable to both active and passive sonar. This paper concentrates on wavelet transform domain implementation of active EC that achieves recombination of multipath and multihighlight signals. This paper reviews the underlying wavelet transform concepts, basic EC theory and medium characterization by wideband spreading and scattering functions. Some computer simulation results are presented. [This work was supported by ONR under Grant No. N000149510965, Code ONR 313.]
Multistatic scattering from bottom targets in the presence of anisotropically rough interfaces
Authors: Lee Jaiyong , Schmidt Henrik
Published: July 2002

The performance of active, multistatic sonar systems can be enhanced significantly, if the 3-dimensional environmental physics is incorporated into the processing. Thus fundamental understanding of the difference between target scattering and bottom reverberation could provide the basis for advanced, multistatic clutter reduction. Strong bottom interaction is the most distinct acoustic feature in shallow-water environments. Consequently, bottom roughness becomes the major reverberation mechanism limiting sonar system performance. To investigate the three-dimensional spatial characteristics of multistatic target scattering and bottom reverberation, a unified numerical model is being developed. It combines existing theoretical models for scattering from shells of finite length, anisotropic interface scattering and seismo-acoustic wave propagation in stratified media. The model generates Monte Carlo statistics for multistatic target scattering in the presence of a strongly reverberant, rough elastic bottom. The effects of anisotropic statistics of the bottom roughness on the multistatic field are investigated, and the significance of the geometric and acoustic properties of target is addressed. [Work supported by ONR.]
Reduced wavenumber synthetic aperture
Authors: Ekhaus Ira
Published: July 2002

Underwater acoustic imaging applications such as mine counter measures and sidescan seafloor surveys would benefit from an operational synthetic aperture sonar system. While the potential of high-resolution synthetic aperture (SA) sonar designs to provide unprecedented detection and discrimination performance is clear, the real-world issues of residual platform motion and temporal/spatial variations in sound speed (SSP) have prevented operational deployment of existing designs. High azimuthal resolution requires a synthesized aperture of lengths approaching ten thousand wavelengths. This imposes a tight constraint on residual motion error and the ranges of environmental scenarios where present designs can operate. Synap Corporation has developed the reduced wavenumber synthetic aperture (REWSA) algorithm/design based on an interferometric preprocessing stage operating on multiple element baseband receptions, and a unique inversion stage. The REWSA algorithm is shown to have a reduced wavenumber characteristic that is inherently robust to the effects of the sonar environment. Discussion of resolution, spatial sampling, and aperture requirements will be supported by simulation and experimental data results. [This work was sponsored by NOAA under Contract 50-DKNA-5-00206.]
Dynamic multiple-use concert hall-theater design and multi-form theater design for the twenty-first century or From dampened steel and reinforced concrete to mosquito netting and back again to dampened steel and reinforced concrete
Authors: Izenour George C.
Published: July 2002

Except for the largest and wealthiest urban centers, it is an undisputed fact that the raison d’etre for design of multiple-use facilities for the performing arts in municipalities of smaller size and relative wealth is an economic necessity for capital as well as for operational funding. Solutions to this many-faceted, much-disputed and much-maligned problem vis-a-vis owners, architects, and engineering consultants have been and continues to be many and varied. Overall in the USA, two schools of thought have emerged. One is continuation of the traditional static architectural approach inherited from the 18th-century high baroque. The other originated and developed by this consultant and favoring a dynamic engineering approach is, instead, firmly rooted in modern times. This paper, accompanied by concise graphic exposition of certain seminal historical and related contemporary realized recent designs and two proposed unrealized designs is an extrapolation into the next century of the author’s technologically based, as opposed to the conventional architecturally based, approach to the problem.
Canine acoustics. II. Frequencies, transmission, and annoyance
Authors: Scheifele Peter M. , Browning David G. , Scheifele Lesa M.
Published: July 2002

In a previous paper [P. M. Scheifele and D. G. Browning, J. Acoust. Soc. Am. 100, 2710(A) (1996)] it was found that the source level for a howling Eastern Coyote is a relatively high 93 dB. At a primary frequency of 500 Hz this howl should have a strong signal throughout a typical territory (4×4 km) under normal atmospheric transmission conditions. Based on reported [H. E. Heffner, Behav. Neurosci. 97(2), 310–318 (1983)] canine hearing response, however, howls appear louder to humans than to canines. For low-frequency noise, such as from road traffic, the opposite is true. This brings up some interesting questions of mutual annoyance which will be discussed.
Potential impacts of low-frequency anthropogenic noise on the hearing of subarctic beluga whales in the Saint Lawrence estuary
Authors: Scheifele Peter M.
Published: July 2002

A small population of about 500 beluga whales, Delphinapterus leucas, resides in the Saint Lawrence estuary, isolated from other populations of its species. This population has been extensively studied over the last 12 years in terms of its seasonal distribution, size, age, group structure, pathology, and group behavior. It is now considered to be threatened by human activities including elevated noise levels due to a wide range of anthropogenic sources including merchant shipping and whale watching activities. A whale recovery plan is in development that will include hearing conservation. Ambient noise measurements mwere made at the three major sites of habitation of these whales to gain an understanding of the daily fluctuations in noise levels and to establish a baseline characterization of the acoustic environment at each site. The noise levels were related statistically by site, time of day, and human activity and compared to beluga hearing sensitivity curves [W. Au, The Sonar of Dolphins (1993)] and indicate the probability that hearing damage will occur for animals occupying two of the three sites. Specifically, 200 Hz, 500 Hz, and 1 kHz and 40 kHz were scrutinized. [Work supported by World Wildlife Fund Canada, Humane Society Canada, and Parks Canada.]
Perceptual effects of simplifying musical instrument sound time-frequency representations
Authors: Beauchamp James W. , McAdams Stephen , Meneguzzi Suzanna
Published: July 2002

The perceptual salience of several outstanding features of musical instrument quasi-harmonic time-variant spectra were investigated. These are: amplitude spectrum shape variation, harmonic amplitude (or frequency) micro-variations, spectral envelope irregularity, harmonic frequency incoherence, and frequency inharmonicity. Seven musical instrument sounds (clarinet, flute, oboe, trumpet, violin, harpsichord, and marimba) were spectrum-analyzed to produce time-varying harmonic amplitude and frequency data. Tones resynthesized from these data were equalized in pitch, loudness, and duration. Six basic data simplifications were applied together with five combinations of them: amplitude versus time smoothing, spectrum shape fixing, spectral envelope smoothing, harmonic frequency coherence, frequency versus time smoothing, and harmonic frequency fixing. Twenty subjects participated in a discrimination study to determine the ease of distinguishing sounds synthesized from simplified data from sounds resynthesized from the full data. Averaged over the seven instruments, the mean discrimination scores were: spectral envelope smoothing, 96%; spectrum shape fixing, 91%; harmonic frequency fixing, 71%; frequency smoothing, 70%; frequency coherence, 69%; and amplitude smoothing, 66%. In conclusion, spectral envelope smoothing had a profound effect (discrimination >95%) for all instruments except the trumpet. Spectrum shape fixing, which eliminates any spectral centroid variation, had a very large effect except for the clarinet and the oboe.
Auditory pitch influenced dramatically by dynamic intensity change
Authors: McBeath Michael K. , Neuhoff John G.
Published: July 2002

Historically, auditory pitch is considered to be principally a function of acoustic frequency with only a small effect due to absolute intensity. Yet, when tones are Doppler shifted, the pitch dramatically rises and falls with dynamic intensity. This study uses a matching procedure to document the magnitude of pitch drop of dynamic Doppler stimuli. Listeners heard Doppler-shifted tones with a mean frequency of either 1046 or 175 Hz, a total fall of 2 semitones, and an intensity change of 58 to 86 dB and back to 58 dB. They compared this drop to a pair of 75-dB, 0.25-s discrete tones that dropped in frequency by intervals ranging from 0 to 24 semitones. The average match between experienced sizes of Doppler and discrete pitch change occurred at a discrete drop of 8 semitones, four times larger than the actual Doppler frequency change. This effect opposes and is an order of magnitude larger than the well known effect due to discrete intensity change. It is proposed that the interaction between dynamic pitch and loudness reflects a natural correlation between changes in frequency and intensity that is neurally encoded to facilitate processing of meaningful acoustic patterns.
Temporal integration of loudness for tones under partial masking
Authors: Florentine Mary , Buus So/ren , Robinson Monica
Published: July 2002

Temporal integration of loudness for 1-kHz tones presented in quiet and under white-noise masking was measured for 5- and 200-ms tones using an adaptive 2I,2AFC procedure. Levels ranged from 5 to 90 dB SL. Results for six listeners with normal hearing show that the amount of temporal integration, defined as the level difference between equally loud 5- and 200-ms stimuli, varies nonmonotonically with level and is greatest at moderate levels. The average amount of temporal integration is about 15 dB near threshold, increases to a peak of 27 dB when the 5-ms tone is about 53 dB SPL, and decreases to about 15 dB near 100 dB SPL. For masker levels of 40, 60, and 80 dB SPL, the amount of temporal integration near masked threshold remains about 15 dB. The maximum amount of temporal integration decreases as masker level increases and occurs at progressively higher levels. At high levels, the amount of temporal integration is nearly the same as in quiet for all masker levels. These results are consistent with the loudness function being steeper near masked threshold than at the same SPLs in quiet. [Work supported by NIH-NIDCD R01DC02241.]
Effect of age on the comfortable loudness range in women
Authors: Rawool Vishakha W. , Pillion Joseph P.
Published: July 2002

This study is designed to evaluate the effect of age on the range of sound pressure levels perceived as ‘‘comfortable.’’ Ten young (22–26 years) and eight older (42–50 years) female subjects participated in the study. All the subjects had auditory sensitivity within 20 dB HL across 0.5 to 4 kHz. Subjects were asked to judge the loudness of warble tones in the following categories: not audible, very soft, soft, comfortable, loud and very loud. The loudness judgments were made at 0.5, 1, 2, and 4 kHz. For any loudness judgement to be considered valid, the same loudness judgment had to be assigned by the subject at least twice to the same sound pressure level. The comfortable loudness range was calculated for each subject by subtracting the highest sound pressure levels judged as ‘‘soft’’ from the lowest sound pressure levels judged as ‘‘loud.’’ The mean ‘‘range of comfortable loudness’’ values for the older female subjects is lower than that obtained from the younger subjects. Additional data are being collected. Following completion of data collection, the data will be submitted to the mixed multivariate analyses of variance. The results and possible implications of the findings will be discussed. [Work supported by Research and Disciplinary grant from Bloomsburg University.]
The effects of aging on specificity of memory representations for spoken words
Authors: Goodman Mara B. , Luce Paul A. , Charles-Luce Jan , Lyons Emily A.
Published: July 2002

Recent evidence suggests that lexical items are stored in memory as detailed exemplars that encode specific information about characteristics of speaker’s voice. Lyons and Luce (1996) found that an incongruity in talker’s voice (male/female) in an explicit recognition task led to slowed reaction times for college-aged participants. While this finding suggests that speaker information is preserved in stored exemplars, it can be asked whether lexical representations of aged individuals are equally detailed. Namely, it has been suggested that with age, phonological representations become more abstract or holistic in nature. If this is true, then a mismatch in talker voice should not affect the performance of aged participants. In order to explore this hypothesis, aged and college participants were tested in an explicit memory task. Preliminary results suggest that older adults are, in fact, more rather than less sensitive to variations in the surface characteristics of spoken words.
Normalization for articulatory recovery
Authors: McGowan Richard S.
Published: July 2002

Articulatory recovery in an analysis-by-synthesis procedure must account for individual differences in vocal tracts. In the procedure described here, all individual vocal tracts are referenced to the vocal tract of an articulatory synthesizer, known as the standard vocal tract. In order to normalize for any given talker, characteristics of the standard vocal tract are adjusted until its sound output closely matches the sound output of the talker over a range of speech sounds. After these standard vocal tract characteristics are fixed, the analysis-by-synthesis procedure is enabled to recover the articulation from the talker. Experiments are conducted with articulatory and acoustic data from the Wisconsin x-ray microbeam database. The midsagittal sections of the standard vocal tract are made to match those of the x-ray microbeam over a set of phones. Characteristics of the standard vocal tract are adjusted so that its acoustic output matches that of the talker as closely as possible over this range of phones. The normalization procedure is checked by choosing a novel utterance for recovery, and comparing the resulting recovered midsaggitals with and without prior normalization. [This work was supported by Grant NIDCD 01247.]
Acoustic estimates of vowel centralization in persons who stutter
Authors: Blomgren Michael , Robb Michael P. , Chen Yang
Published: July 2002

The magnitude of tongue movement for fluently produced utterances of persons who stutter and those of normally fluent controls was inferred through examination of the vocal tract vowel space. Fifteen adult males served as subjects comprising separate groups of untreated stutterers, stutterers who had completed a fluency-shaping treatment program, and nonstuttering controls. The steady-state portion of formant one (F1) and formant two (F2) was examined in the production of various CVC tokens embedded in a carrier phrase. Average F1 and F2 values for |i|, |a|, and |u| were plotted in an F1−F2 vowel space triangle for each subject. The corresponding vowel space was measured by determining the area (Hz2) of the triangle. Results indicated the untreated group of persons who stutter had the smallest average vowel space, while the largest vowel space was observed in the control group. Discussion focuses on the vocal tract articulation characterizing fluent speech production.
Acoustic, aerodynamic, and physiological characteristics of modal and vocal fry registers
Authors: Chen Yang , Blomgren Michael , Ng Manwa L. , Gilbert Harvey R.
Published: July 2002

This study examined production of the modal and vocal fry registers using various acoustic and aerodynamic parameters. Airflow (AF), air pressure (AP), electroglottalgraphic (EGG), and acoustic data were obtained simultaneously for four isolated vowels (/i/, /æ/, /a/, /u/) and the stop consonant produced in a string of /pi/ syllables for both modal and vocal fry registers. Twenty normal speakers (10 males, 10 females) who were able to produce vocal fry participated in this study. Results demonstrated considerable differences among AF, AP, EGG, and acoustic signals for the modal and vocal fry registers. The fundamental frequency in vocal fry register (male: 49.1 Hz; female: 48.1 Hz) was found to be significantly lower than that in modal register (male: 117.5 Hz; female: 211.0 Hz). Also, the average air pressure values decreased in vocal fry register (male: 5.51 H2O; female: 5.25 H2O) compared to values obtained in the modal register (male: 7.45 H2O; female: 7.56 H2O). In vowel production, the airflow rate in the modal register was almost three times as high as the airflow rate in vocal fry register. For the production of /pi/, airflow rate associated with the stop consonant in the modal register was approximately 1.5 times higher than that in the vocal fry register.
Sensitivity to key movement in a Beethoven excerpt: Theory and evidence
Authors: Cuddy Lola L. , Smith Nicholas A.
Published: July 2002

After a brief introduction to historical and contemporary descriptions of musical key, key relationships, and key movement, the results of two experiments testing convergence of music theory with listener response will be reported. Perceptual sensitivity to key and key movement in the opening measures of the second movement of Beethoven’s piano sonata Opus 53 (Waldstein) was evaluated by the probe-tone technique. Listeners were either familiar (experiment 1, n=14) or unfamiliar (experiment 2, n=14) with the excerpt. The excerpt was performed by an experienced pianist and recorded as MIDI files. On each trial, the excerpt was presented from the beginning to one of nine successive time points. Time points were the first beat, the first bar, and each successive bar. For each time point there were 12 presentations, each followed by a probe tone, and 1 of the 12 chromatic divisions of the octave randomly selected without replacement. Listeners judged the goodness-of-fit of each probe tone to the music presented; the set of 12 ratings yielded a probe-tone profile. A significant proportion of profile variance was accounted for by quantified music-theoretic and psychoacoustic predictors, the proportion increasing with familiarity. [Work supported by NSERC.]
Boundary conditions for finite-difference PE solvers
Authors: Yevick David , Thomson David J.
Published: July 2002

In theoretical/numerical models of underwater sound propagation, a downgoing radiation condition is usually imposed on the acoustic field as z→∞. For most implementations of parabolic equation (PE) solvers, this condition is approximated by appending an absorbing layer to the computational mesh. Such a layer acts to attenuate any energy that reaches the grid boundary before the waves undergo reflection and return to the ocean region. As shown by Papadakis [J. Acoust. Soc. Am. 92, 2030–2038 (1992)], this approximate treatment can be replaced with a nonlocal boundary condition (NLBC) that exactly transforms the semi-infinite PE problem to an equivalent one in a bounded domain. Papadakis’ method involves evaluating a spectral (wave number) integral of a singular kernel that is inversely proportional to the impedance of the subbottom medium. In this paper, an alternate procedure is described for obtaining NLBCs directly from the z-space Crank–Nicolson formulations of both the Tappert and Claerbout PEs. Formulas for the boundary field at range r+Δr are derived in terms of the known field along 0→r by expanding the appropriate ‘‘vertical wave number’’ operator in powers of ℛ=exp(−Δr∂r) and applying ℛ jψ(r,z)=ψ(r−jΔr,z). The effectiveness of these NLBCs is compared to Berenger’s matched-layer technique [J. Comp. Phys. 114, 185–200 (1994)] for several numerical examples relevant to one-way underwater sound propagation.
Human vibration standards–Do we ask the right questions?
Authors: Erdreich John , Erdreich Linda S.
Published: July 2002

Standards for vibration exposure promulgate different limits for hand–arm vibration (HAV) and for whole-body vibration (WBV). The discrepancy between the two should be explainable on some rational basis [Griffin, Handbook of Human Vibration (1990)], but there is no obvious difference in the mechanism of pathogenesis to the skin at each of the sites. The difference may arise because the endpoints chosen as the basis of each of the standards are different. One approach to estimating dose response [Jarabek, Toxicol. Lett. 79, 171–184 (1995)], characterizes the steps in developing a model as proceeding from a protective to a predictive paradigm as data progress from qualitative to quantitative. To develop vibration standards along this continuum, certain data must be developed: Among these are identification of performance effects of HAV, identification of long-term effects of WBV, and clarification of the impedance of the affected biological structures. Some of these areas have been addressed in recent revisions of ISO TC108/SC4 standards. Other activities will be proposed to further the evolution of human biodynamic assessment.
The theory of mental testing and the correlation between physical noise level and annoyance
Authors: Kalveram Karl Th.
Published: July 2002

Applying the ‘‘theory of psychological testing,’’ physical noise measurement procedures are regarded as ‘‘tests’’ variables and the related annoyance as the criterion variable. The concepts of ‘‘reliability,’’ ‘‘validity’’ and ‘‘equivalence’’ then can be used to assess the precision of different noise measurements. Referring to data of an investigation on aircraft noise in the vicinity of Munich Airport in 1969, in which different physical as well as annoyance data were sampled from the same subjects, it turns out, that the measurements called Leq1, Ls, Leq3, Leq4, NNI and FB1 meet the equivalence criterions of test theory, that is, they cannot statistically be distinguished, and their coefficients of reliability are close to one. Other measurements like D10, H81, log N and Leq10, equivalent to the former six. However, even the former six are only of moderate validity (about 0.5). Regarding psychological testing, therefore, physical noise is only a poor measure when used to predict individual annoyance, but it suffices when used to predict group averages. Moreover, it can be concluded from the theory that the attempt to enhance validity by modification of the highly reliable physical measuring procedures cannot be successful. It would be more effective to enlarge the reliability of the psychological measurement procedures of annoyance.
W. Dixon Ward—Professor, mentor, university citizen
Authors: Carney Arlene Earley
Published: July 2002

W. Dixon Ward had a colorful and active presence in the scientific community and in the Acoustical Society of America as an officer, editor, presenter, and author. Many of his ideas and much of his written work sparked debate and discussion. On the homefront at the University of Minnesota, he had an equally colorful presence as a mentor to graduate students and as a frequent and controversial letter writer to the Minnesota Daily, the university newspaper. Selections of Dix’s letters on a variety of topics from word usage to university and world affairs will be presented. In this introduction, Dix’s professional life outside the Acoustical Society will be reviewed and discussed through the eyes of his students and colleagues.
The forward and backward projection of harmonic pressure fields from complex three-dimensional bodies
Authors: Stepanishen Peter R.
Published: July 2002

The forward and backward projection of pressure fields from complex three-dimensional harmonically vibrating bodies is an important problem in noise control. A new generalized internal source density (GISD) method is presented to address the projection problem. The GISD approach is based on decomposing the pressure field on a closed surface of revolution in the fluid into a summation of circumferential orders where the pressure field for each order is associated with an internal linear distribution of ring sources on the axis of revolution. The axial variation of each source distribution is formulated as the solution of a mean square error problem and the resulting distributions can then be simply used to determine the entire external and/or surface pressure and velocity fields of the vibrating body. Analytical and numerical results are presented for several examples to illustrate the basic approach for bodies with different aspect ratios. Exact expressions for the source strength distributions for a sphere are developed and shown to have a vanishingly small region of support about the center of the sphere. For cylindrically shaped bodies with large aspect ratios, the spatial characteristics of the source strength distributions more closely match the normal velocity distribution.
An analytical solution for a rectangular piston independently driven at two edges
Authors: MacGillivray John
Published: July 2002

Far-field radiation of a baffled rectangular piston is described using a frequency-domain Rayleigh integral solution. The piston model is driven at a single frequency at two opposing edges, where these individual edge sources are independent of one another in both amplitude and phase. Directivity plots of the analytical solution are used to graphically observe directional effects caused by changing the phase and amplitude of these edge sources. Interesting and unexpected beamforming characteristics are shown to be produced by certain amplitude and phase combinations. [Work supported by IBM through the Shared University Research program and the Applied Research Laboratory at Penn State Univ. University.]
Accurate determination of total sound power radiated from a rectangular panel
Authors: Li W. L. , Gibeling H. J.
Published: July 2002

Radiation of sound from planar vibrating panels has been extensively studied for years. In most of these investigations, the total sound power is approximately obtained from the modal radiation efficiencies without considering the contributions from modal cross couplings. The primary reason for doing this is perhaps that the inclusion of cross-coupling terms may result in a tremendous increase in computational load, particularly when a large number of structural modes is involved. In a recent paper [R. D. Snyder and N. Tanaka, J. Acoust. Soc. Am. 97, 1702–1709 (1995)], an approximate estimate of the cross-coupling terms from the modal radiation efficiencies was discussed. It is, however, valid only in a low-frequency range and deteriorates rapidly as frequency increases. In this paper, the effect of modal cross couplings on the total sound power radiated from a simply supported rectangular panel is discussed. A formula is derived for an accurate and efficient calculation of the cross-coupling terms which allows for effortlessly including the effects of the modal cross couplings in the total sound power calculation. In addition, the present formulation is valid in the whole frequency range. Results are presented.
Temporal characteristics of coarticulatory vowel nasalization in English
Authors: Tanowitz Jill , Speeter Beddor Patrice
Published: July 2002

Previous research has shown that, in English /VNC/ sequences, vowels and nasal consonants are shorter when the final oral consonant is voiceless than when voiced [O. Fujimura, Symp. on Articulatory Modeling, Grenoble (1977)]. This study investigates whether consonant voicing affects the temporal characteristics of coarticulatory vowel nasalization, as well as V and N duration. Specifically, is vowel nasalization proportionately longer in voiceless contexts, compensating for the shorter N? Speech materials are multiple instances of real-word and nonsense /bVNC/ sequences (V=/i I e ε æ/, N=/m n ■/, C=/p t k s/ and /b d g z/) produced by four American English speakers. Temporal measures include duration of V, N, C and vowel nasalization. Onset of vowel nasalization was identified as onset of the nasal formant and/or widening of formant bandwidth in the low-frequency region of FFT spectra sampled across the vowel in 10-ms increments. Vowel duration was on average 20% shorter and N duration 40% shorter in voiceless than in voiced contexts. However, vowel nasalization duration was not compensatorily longer in voiceless contexts. Regardless of N duration, coarticulatory nasalization remained a constant proportion (about 80%) of total vowel duration across all segmental contexts. Variation in this proportion across vowels and speakers is minor. [Work supported by NSF.]
A longitudinal investigation of duration and temporal variability in children’s speech production: Additional data
Authors: Smith Bruce L. , Kenney Mary Kay
Published: July 2002

To follow up on an earlier, 11/2-yr longitudinal study of temporal characteristics in speech production development [Smith et al., J. Acoust. Soc. Am. 99, 2344–2349 (1996)], the same 12 children were seen again to extend the analysis interval to about 3 yr. The children ranged from approximately 7–12 years of age initially to about 10–15 years at the end of the study. For each recording, they produced 25 repetitions of each of several different words and short phrases, from which various segments and syllables were measured. Duration and temporal variability measures for up to half the subjects demonstrated nonadultlike performance at the initial and intermediate recordings, whereas average duration and variability were within an adultlike range for all 12 children by the final session. In general, the greatest decreases across the 3 yr occurred during the first 11/2 yr, particularly regarding temporal variability; however, small decreases in duration and variability occurred from the intermediate to the final recording, as well. A tendency was also observed for children whose average segment duration or variability was more adultlike at the initial recording to show more adultlike values at the intermediate and final recordings.
Methods for acoustic-to-articulatory mapping and voice mimic systems
Authors: Chennoukh S. , Sinder D. , Richard G. , Flanagan J.
Published: July 2002

The articulatory codebook approach to voice mimic systems is complicated by large amounts of data and expensive acoustic comparisons when searching the codebook. If, during codebook construction, the acoustic parameters are quantized and mapped back to the articulatory space, the inverse is accomplished without acoustic comparisons. Since the inverse is nonunique, articulatory trajectories must also be estimated to resolve acoustic parameters which map to multiple model shapes. This can be managed with a tracking technique that uses dynamic properties (position and velocity) of each articulatory parameter to estimate the next model shape. A recurrent algorithm results which finds an optimal path through the model shape variations. These approaches are helpful, but they do not address the problem that codebooks may not cover the entire articulatory space. Furthermore, there is no performance measure which indicates the extent of the coverage. This limitation is overcome by an analytic inverse mapping, rather than a table look-up, which relates the first two formant frequencies with articulatory parameters. This relationship, which is well established for vowels, uses a distinctive region model (DRM) to approximate three area function parameters as a function of the first two formant frequencies. [Research supported by ARPA DAST 63-93-C-0064.]
Sound-field sensitivity to geoacoustic parameters in range-dependent media using normal modes
Authors: Kessel Ronald T.
Published: July 2002

Sensitivity in sound propagation modeling is a measure of the ability of environmental parameters to affect the sound field. The most sensitive parameters are often considered most important because errors or uncertainties in their values are among the most likely sources of error in the model predictions. There are many ways to define the measure of sensitivity. It generally depends on the sound field itself, on the energy flow through regions where the geoacoustic parameters under consideration lie, and on the way the field is monitored by receivers. But it is useful to define sensitivity without reference to a particular field or source–receiver configuration, as if it were a parameter of the environment alone. Then conclusions drawn from a sensitivity study apply as much as possible to all source–receiver configurations, and for both inverse and forward modeling. Such a measure has been derived using an adiabatic mode model for range-dependent media, exploiting the fact that the normal modes of vibration embody the essential properties of the field without reference to a particular source–receiver configuration. The new measure is demonstrated for range-dependent media using computer simulations.
The generalized eigenvalue problem, warping matrices, and the transformation of an isovelocity environment to a variable velocity environment
Authors: Werby M. F. , Sidorovskaia N. A.
Published: July 2002

The calculation of eigenvalues for a layered isovelocity oceanic environment and associated vertical modes is very quick and easy to do. A method of transforming the isovelocity problem to a variable velocity problem, by means of a matrix transformation based on the theory of generalized eigenvalues, is described. Along with modern transformation techniques, the rapid reconstruction of variable velocity solutions is demonstrated. It is possible to determine the mode spectrum extremely rapidly by first starting out with those associated with a reference isovelocity eigenvalue set, and then by using an iteration procedure based on integral transform methods, the Householder transformation, polar decomposition theorems, shifting, and deflation methods in linear algebra to converge to the set of eigenvalues rapidly. A first iteration may take a fraction of a second to calculate on a PC, while full iteration takes on the order of a second to calculate 100 eigenvalues. [Work sponsored by ONR, the Naval Res. Lab., and the Univ. of New Orleans.]
The auditory nerve in congenitally deaf white cats: Correlations between anatomy and electrophysiology
Authors: Ryugo David K. , Rosenbaum Brian T. , Pongstaporn Tan , Saada Ahmed A. , Niparko John K.
Published: July 2002

It is well known that cochlear pathology produces alterations in neurons of the cochlear nucleus, but there are few data that directly relate such neuronal changes to the physiology of auditory nerve fibers and structure of auditory nerve endings. These relationships are addressed in a naturally occurring model of deafness, the congenitally deaf white cat. Cats with no intact organ of Corti exhibited no measurable hearing thresholds and had severely reduced spontaneous activity in single auditory nerve fibers. Furthermore, there was structural atrophy of endbulbs of Held in the anteroventral cochlear nucleus, and hypertrophied synapses. These hypertrophied synapses were characterized by large postsynaptic densities with highly thickened membrane specializations and markedly diminished numbers of synaptic vesicles. Cats with elevated but measurable hearing thresholds had normal-appearing organs of Corti with abundant spontaneous single unit activity but infrequent sound-evoked activity. These partially deaf cats displayed modest atrophy of their endbulbs and exhibited more normal appearing synapses. The data reveal that early onset partial or total deafness that is uncorrected for 6 months or more produces unambiguous alterations in synaptic structure. These observations are relevant to selection strategies for human cochlear implant candidates. [Work supported by NIH/NIDCD.]
The role of the brain in the functional development of the ear
Authors: Walsh Edward J. , McGee JoAnn
Published: July 2002

The olivocochlear bundle (OCB) invades and organizes within the organ of Corti around the time of birth in cats, roughly coincident with the first detectable sound-elicited responses from the cochlea or auditory nerve. A model of innervation is proposed, in which the medial OCB (MOC) regulates the development of both inner (IHC) and outer hair cell (OHC) systems. In stage 1, early arriving fibers of the MOC make transient axosomatic synaptic contact with IHCs, rhythmically modulating their transduction currents. Operating through an excitatory synapse, the MOC contributes to an activity-dependent system through which exuberant auditory nerve fiber contacts with IHCs are refined. In stage 2, MOC fibers detach from IHCs, migrate across the tunnel of Corti, and contact OHCs forming their well recognized calyces with the basolateral wall of the cell, and in the process ‘‘energize’’ the cochlear amplifier. By removing the OCBs influence at birth, prior to the completion of its innervation of the cochlea, its role during development can be evaluated. The otopathology resulting from neonatal cochlear differentiation is consistent with the overall predictions that would be made based upon the proposed model. [Work supported by NIH/NIDCD.]
Scattering calculations by a hybrid GTD-boundary integral equation method
Authors: Barbone Paul E. , Michael Ofer M.
Published: July 2002

We consider the application of a hybrid asymptotic/boundary integral equation (BIE) method to the problem of scattering from prismatically shaped objects. The hybrid method is based on patching a short wavelength asymptotic expansion of the scattered field to a BIE evaluation of the near field. In patching, the diffracted field shape functions with unknown amplitude are forced to agree smoothly with the solution in the near field along a curve at a prescribed distance from the diffraction points. This allows us to replace the original boundary value problem with an asymptotically equivalent boundary value problem, the domain of which is small and efficiently discretized. Since the domain of the numerical problem is small and may be chosen at will, we completely circumvent non-uniqueness problems associated with ‘‘forbidden frequencies.’’ Thus very high-frequency calculations can be performed using single layer potential equations with no problems of ill conditioning. The hybrid scattering solution shall be compared to a complete analytic field representation found using matched asymptotic expansions. [Work supported by ONR.]