bluuebunny/crossref_metadata_2025 huggingface dataset:
The recent past, present, and near future of variable volume auditoria for the performing arts—Three generations 1965–1985
Authors: Izenour George C.
Published: October 2005

Ten projects selected from the author's consulting practice are analyzed with the help of graphics in plan, longitudinal perspective section and transverse section, and photographs of completed projects. The paper is divided into three sections. The First Generation: Initial attempt at integration of massive electromotively driven structures with control logic. Vertically displaced modular panel arrays. (Jesse Jones Hall, Houston, Texas, 1966.) The Second Generation: Sophistication of structure and control logic. Vertically displaced and hinged rigid structural and catenary cable supported randomized panel arrays. (McCain Auditorium, Kansas State University, Manhattan, Kansas, 1971; O'Shaughnessy Auditorium, St. Catherine's College, St. Paul, Minnesota, 1971; Viterbo College Auditorium, La Crosse, Wisconsin, 1971; Edwin Thomas Hall for the Performing Arts, Akron University, Akron, Ohio, 1973.) The Third Generation: The sophistication of fooling eye but not the ear and the building budget crunch. Vertical displaced—logic controlled thin-skinned contiguous structures, down light fields, and massive absorption manipulation. (Civic Auditorium, El Paso, Texas, 1974; DeVos Hall, Grand Rapids, Michigan, 1980; Two low-cost performing arts halls: St. Anselm's College, Manchester, New Hampshire, 1981; University of South Carolina at Aiken, South Carolina, 1982; Performing Arts Hall University of South Carolina at Columbia, South Carolina, 1985.)
Electro-acoustic factors determining telephone speech quality
Authors: Gruber John G. , Williams Godfrey
Published: October 2005

In this presentation the electro-acoustic factors affecting the quality of telephone speech are shown to consist of: (1) Listening factors such as loudness, noise, and frequency shaping (2) talking factors such as echo and sidetone, and (3) conversational factors such as delay. Listening factors in particular are qualitatively interpreted in terms of the effect of telephone connection loss and frequency shaping on speech loudness at the ear relative to the hearing threshold, as well as the effect of noise on the hearing threshold. We then consider a typical telephone connection in which combinations of the above factors are manifested; this is done in the context of a hardware simulation facility used by BNR to simulate various telephone network impairments for the purposes of objective and subjective evaluation, and grade-of-service studies. Finally various grade-of-service results are presented pertaining to connection loudness loss and noise, talker and listener echo in conjunction with delay, and the subjective equivalence of continuous and speech correlated (quantization) noise.
Real voice characterization of carbon transmitters
Authors: Koenig Arthur H.
Published: October 2005

Recent data provided to the International Telegraph and Telephone Consultative Committee (CCITT) suggest that artificial voice characterizations of carbon transmitters are not necessarily equivalent to real voice characterizations. The present study involved, first, the development of a methodology for measuring real voice transmitting responses and, second, the examination of 10 different carbon transmitters (five designated as two-port and five designated as four-port) using this methodology. Real voice transmitting responses obtained from 10 subjects for each transmitter were compared to the artificial voice transmitting response obtained for the same transmitter. Real and artificial voice characteristics obtained for the two-port devices were shown to be in close agreement whereas a modest but systematic difference in the form of low-frequency enhancement was found for the four-port devices.
A summary of the sound pressure level transformations from free and diffuse sound fields to the human torso, head, and ear
Authors: Kuhn George F. , Guernsey Richard M.
Published: October 2005

The sound pressure level (Lp) measured at a particular location on the human head or torso differs from the level in the empty sound field because sound is scattered by the head and body. The difference between the level measured near the head or torso and the level measured in the empty field is defined here as the sound pressure level transformation. Previous measurements of these transformations are summarized and presented as a function of frequency, microphone location, type of incident sound field, and angle of incidence (in the horizontal plane). For the most part, these transformations are positive: the levels near the head or torso are greater than those in the empty sound field. Differences in the results of various studies are pointed out. Further studies are proposed to resolve the differences and provide additional information. Some simple guidelines for choosing a free or diffuse field transformation in a real environment are presented. The choice depends on source directivity, distance between source and subject, and the sound absorption of the surrounding volume.
Worker noise exposure using time-resolved noise dosimetry
Authors: Thornton William R.
Published: October 2005

Using the recent technological advances of time-resolved noise dosimetry, comprehensive controlled studies, and field work have been performed to assess worker noise exposure. Emphasis has been placed on assessing exposures and obtaining baseline data for implementing controls where overexposures exist. Because of the mobility of workers on a daily basis, time-resolved dosimetry has been analyzed using inferential statistics to estimate exposure levels. Controlled studies have been used to develop a model and validate the procedure. Finally, time-resolved dosimetry has been coupled with colored noise contours and time-motion studies to determine where controls are required when overexposures are sufficient to warrant action. Implications of this work for a total hearing conservation program and for a future course of action are discussed.
Laryngeal-oral coordination in the production of obstruents by hearing impaired speakers
Authors: McGarr Nancy S. , Löfqvist Anders
Published: October 2005

The study examines the organization of laryngeal control and inter-articulator timing in the production of voiceless obstruents by hearing impaired speakers. Three severe-profoundly deaf adults served as subjects. Laryngeal activity was monitored by trans-illumination; temporal patterns of oral articulation (lips and tongue-palate) were recorded using an electrical transconductance technique. For each of the deaf speakers, an inappropriate abduction gesture immediately preceded production of the test word, a pattern never observed for hearing speakers. However, the deaf speakers differed from each other with respect to type of errors, variability, and interarticulator coordination. For the more intelligible deaf speaker, the timing of glottal opening with respect to oral articulation was most like that observed for normals. The second deaf speaker often failed to observe voicing contrasts with respect to glottal opening; that is, he failed to produce an opening gesture for voiceless obstruents as normals. For the third deaf speaker, the pattern of errors appears to be more complex including both missing and inappropriate glottal opening gestures. Data will be discussed with respect to listener judgments. [Work supported by NINCDS and BRSG.]
Asymptotic theory of discrete normal modes in inhomogeneous planar waveguides
Authors: Parmatoni Ronald F.
Published: October 2005

Arnold [J. Acoust. Soc. Am. 69, 17 (1981)] has applied the method of comparison equations to obtain complete asymptotic solutions to the two turning point eigenvalue problem for the Schroedinger equation with boundary conditions imposed at finite boundaries. We present a different analysis of this problem employing the method of matched asymptotic expansions to connect higher order asymptotic solutions at each simple turning point obtained by means of Cherry's technique. The advantage of this approach is that it extends to the treatment of multiple turning point problems for which the canonical global comparison equations have no well-studied solutions. As a further application of these ideas, we present a higher order asymptotic analysis of a three turning point eigenvalue problem for the Schroedinger equation with boundary conditions imposed at finite boundaries. Such a problem arises from a normal mode analysis of underwater acoustic propagation when a surface duct lies over a deep sound channel. This analysis includes an extension of Cherry's technique to the transition problem associated with the barrier between the surface duct and the deep sound channel.
The projection of acoustic fields from axisymmetric ultrasonic radiators using impulse response and Hankel transform techniques
Authors: Medeiros Anthony F. , Stepanishen Peter R.
Published: October 2005

A generalized impulse response approach is reviewed to evaluate the harmonic pressure field of ultrasonic planar radiators having axisymmetric nonuniform velocity distributions P. R. Stephanishen (J. Acoust. Soc. Am. Suppl. 1 62, S68 (1977). The harmonic pressure is expressed as a Fourier transform of the generalized impulse response which is a function of the spatially nonuniform velocity of the vibrator. A backward projection method is then developed to reconstruct the velocity of axisymmetric vibrators from harmonic field pressures using angular spectrum or Hankel transform formulation. The near and farfield pressure for vibrators having both uniform and nonuniform velocity distributions is presented and then used to determine the numerical accuracy of the backward projection technique. This technique is then used to experimentally evaluate the velocity distribution over the surface of a uniformly driven piezoelectric ceramic disk and ceramic ring using farfield measurements of the complex pressure. Phase errors in the reconstruction process are shown to be the result of inadequate separation distances defined by standard Rayleigh distance farfield criteria.
Growth and recovery of TTS
Authors: Melnick William
Published: October 2005

The magnitude of TTS is a function of the physical properties of the fatiguing sound including the spectrum (frequency and intensity), duration, and temporal pattern. TTS is also a function of the test conditions under which the hearing threshold is measured, notably the test frequency and the time interval between sound stimulation and threshold measurement. The relationship of growth and recovery of TTS to the important test and stimulus variables which have evolved from studies conducted since 1950 will be reviewed briefly to provide a background for considering the more recent research developments.
Effects of signal parameters on phase detection in lateralization
Authors: Abel Sharon M. , Kunov Hans
Published: October 2005

A series of experiments are in progress to evaluate the relative contribution of onset and phase cues in binaural hearing. An initial study of the lateralization of a 1-kHz tone showed that for interaural phase shifts in the region of 90° to 270°, performance was critically dependent on the rise-decay time (R/D) of the signal [H. Kunov and S. M. Abel, J. Acoust. Soc. Am. Suppl. 1 67, S6 (1980)]. Surprisingly long R/D times (200–599 ms) were necessary to preclude contributions from the onset cue. Followup experiments have been conducted to investigate the effects of the shape of R/D, as well as intensity, frequency, and duration of the signal on interaural phase detection. The results indicate that for a short R/D of 5 ms subjects respond entirely to interaural onset difference: Performance is unaffected by variation in the shape of R/D, signal intensity, or frequency. As R/D increases to 200 ms the onset cue is superceded by interaural phase detection: The relative use of the two cues is determined by the unique combination of the three parameters. The dominance of onset over phase cue increases with intensity, decreasing R/D, and with linear as compared with sigmoidal shape of R/D. Phase detection decreases as frequency increases. A change in the duration of maximum amplitude of the signal from 25 to 200 ms does not affect performance for any R/D time. [Work supported by Natural Sciences and Engineering Research Council, Canada.]
Detection of interaural delay in high-frequency noise
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2005

Subjects' ability to detect interaural time delays was investigated with four 240-Hz widebands of noise centered at 4-kHz which differed only in the slope of their low-frequency skirts. Sensitivity to interaural delay increased dramatically with decreases in the slope of the low-frequency skirt. Performance was unaffected by the addition of 3-kHz, high-pass noise and seriously degraded by the addition of 3-kHz, low-pass noise. When only the low-frequency skirt of one of the four noise bands was presented, performance was slightly poorer than that obtained with the entire band. The data strongly suggest that the primary cue was provided by interaural delays of the low-level, low-frequency portions of the nominally high-frequency bands of noise. That is, consistent with Yost et al. [W. A. Yost, F. L. Wightman, and D. M. Green, J. Acoust. Soc. Am. 50, 1526–1530 (1971)] who used transients, the subjects were not utilizing differences in the envelopes of the high-frequency noise bands.
A model for the perception of reiterated noise at low repetition frequency
Authors: Hartmann W. M.
Published: October 2005

Periodic modulation of a signal may be perceived by a spectral process or by a temporal process. R. M. Warren, J. M. Wrightson, and H. E. Storck [J. Acoust. Soc. Am. Suppl. 1 67, S21 (1980)] have performed an interesting experiment exploring the transition between these two perceptual regimes. They determined the perceived periodicity of repeated noise segments having alternating polarity; they found a transition at a repetition frequency of about 70 Hz. We have analyzed this experiment with a model of the auditory system consisting of frequency analysis, square-law detection and leaky integration. The model provides a time-variant spectral analysis of an arbitrary signal. It interpolates between long-term and short-term spectral representations. Using model parameters for spectral resolution and minimum integration time taken from other psycho-acoustical experiments we obtained model predictions in good agreement with the data of Warren et al. The calculations imply that the perception of low-frequency periodicity in this experiment is not properly an aspect of pitch perception. [Supported by NSF grant BNS 79-14155.]
Sequential estimation of percent correct
Authors: Gabriel Kaigham J.
Published: October 2005

A sequential estimation and decision procedure is presented as an easily implemented alternative to adaptive methods. Unlike adaptive methods, the procedure does not alter stimulus values during the course of a run in order to converge at a desired level of performance. Instead, the procedure inspects a subject's cumulative performance at the end of each trial and, based on a set of well defined criteria, decides whether to continue or terminate the run. If the subject is performing well above or below the level of performance specified by the experimenter, the procedure stops the run. If the subject is operating near the specified level, the procedure continues the run (unless the specified maximum number of trials has been reached, in which case it stops the run). Regardless of why the procedure stops, a percent correct is estimated at the end of each run. In our experience, this procedure provides approximately a 50% saving in time over the fixed-number-of-trials procedure. [Work supported by NIH.]
Effects of vowel quality on stress production in disyllables with reference to perceptual centers
Authors: Smith Mary R.
Published: October 2005

Listeners appear to make use of a complex relation of relative vowel quality differences, syllable duration differences, and syllable position effects to perceive stress in synthesized disyllables in English. The present experiment tests whether speakers make use of the same sort of information in articulating disyllables. Four speakers produced rate-controlled sets of tokens with first, and second syllable stress of twelve disyllables that differed in the component vowels. Tokens were elicited under two conditions: Where the sequence of tokens were identical in both stress pattern and vowel composition, and where the tokens alternated in either stress pattern, vowel composition, or both. Preliminary results of spectrographic analyses show correlations of stressed vowel durations with vowel quality, in addition to correlations with syllable position and elicitation conditions. The findings lend support to the view that perceptual centers correspond to articulatory activity related to the stressed vowel.
Multipath propagation loss measurements over an isolated seamount
Authors: Chapman N. R. , Ebbeson G. R.
Published: October 2005

The interaction of low-frequency sound with an isolated seamount has been studied by examining the multipath propagation. The data were collected during a shot run carried out over Dickins Seamount in the northeast Pacific. 1.8-lb SUS charges were detonated at depths of 21 and 188 m along a 130-km track beginning near a receiver suspended at a depth of 329 m, 60 km from the seamount. The multipath propagation loss was measured in 13 octave bands from 25–400 Hz. The results for both source depths indicate a region of decreased propagation loss (enhancement) before the seamount where a strong reflection is observed, and a region of shadowing beyond the seamount. In the shadowing region there are only two significant arrivals observed, and the relative arrival time remains constant with increasing shot range. The strength of these arrivals reaches a maximum when the source is about a convergence zone beyond the seamount. The shadowing effect is frequency-dependent, with the propagation loss increasing at low frequencies. These observations are interpreted in terms of a simple model to account for the effects of the seamount.
Long-range sound propagation across Atlantic Ocean seamounts: Implications for ambient noise
Authors: Koenigs P. D. , LaPlante R. F. , Browning D. G. , Martin R. L.
Published: October 2005

A low frequency (50–800 Hz) sound-propagation experiment was conducted along a 1400-km path running eastward from Bermuda toward the Mid-Atlantic Ridge. SUS charges were detonated at depths of 18, 154, 615, and 1230 m. The receiver was located at the axis of the deep sound channel (1250 m) at a range of approximately 1300 km. The acoustic path crossed several seamounts of the Corner Seamount Group. The highest of these peaks rose to the sound axis. This paper presents the relative enhancement of signal level for SOFAR propagation due to these seamounts as a function of source depth and frequency. The enhancement was minimal for the 1230-m shots, while the greatest enhancement occurred for the 18-m shots at the 50-Hz filter band. This implies these seamounts and other topographic features such as the Mid-Atlantic Ridge can significantly increase the coupling of low-frequency ship-generated noise into the deep sound channel. [Work supported by NAVSEA.]
Tissue viscosity at ultrasonic frequencies using the transient thermoelectric technique
Authors: Frizzell L. A. , Goss S. A.
Published: October 2005

The transient thermoelectric technique has been used many years for field plotting, transducer calibration, and determination of the absorption coefficient in highly absorbing liquids and tissues. A theoretical model was developed which provides the temperature measured by a thermocouple imbedded in an absorbing medium and has been shown in preliminary studies to give good correlation with experimental data (1977 Ultrasonics Symposium Proceedings, pp. 206–211). Recent studies employing this model suggest that the transient thermoelectric technique may provide a useful approach to the measurement of other parameters, such as viscosity. The approach involves the variation of tissue viscosity, in the model, to fit theoretical to experimental data. This technique provides the possibility of making viscosity measurements in vivo as well as in vitro. Results using this method in Dow Corning 710 silicone oil agree well with known values of viscosity. Initial results in tissues in vitro suggest that the effective viscosity, at 1 MHz and 37°C, of tendon may be substantially larger than that for testis. [This research was supported in part by grants from the National Institutes of Health and the Indianapolis Center for Advanced Research.]
Developments in axicon imaging for large depth of focus
Authors: Clarke R. L. , Bamber J. C. , Hill C. R. , Wankling P. S.
Published: October 2005

It is known that the resolution possible from a system based on strongly convergent conical wave fronts is capable of transverse and longitudinal resolution of the order of a wave length. Further, this system (“axicon”) should maintain this resolution throughout the region in which the waves converge on an axis. It is, in effect, an imaging device with a very wide aperture and large depth of focus. The latter offers promise for acoustical imaging of certain organs, such as the breast. We have built an axicon designed for a depth of focus of 10 cm, with a convergence half-angle of 30 degrees. It consisted of a 4-MHz plane transducer, whose beam was first spread out, then reformed into the conical shape by two axially symmetric, nonspherical mirrors. The system, tested with a fine wire target, gave a beam profile close to theoretical expectation. Wide “skirts” are observed. When used for imaging, it gave the expected resolution, but the skirts gave rise to noise and certain artifacts. The expected depth of focus was observed.
A new consideration for sonar systems
Authors: Wu Wei Tseng
Published: October 2005

This paper deals with a system for detecting underwater acoustic waves. It consists of laser exciters, optical elements, and an electronic computer. Instead of using a piezoelectric or magnetostrictive transducer, the signal is to be displayed by applying a double-exposure holographic technique based on the varying refractive index of light in the sonic field. The image formed from the signals is to be Fourier transformed by optical systems and filtered in the frequency domain. In this two-dimensional image detection approach, as it is called in this paper, the sensitivity is improved due to much more plentiful information existing in the two-dimensional image as compared with the one-dimensional signal which is produced from a general transducer. In the monitor and identification section an electronic computer operates according to the f(x,y) = g(x,y) − kΣ∇2g(x,y) formula to sharpen the image edges and acts as a match filter to identify the target signals. Experiments have been conducted and satisfactory results obtained.
Study of shadow region of obstacles by ultrasonic diffraction for NDE
Authors: Latimer Jerry , Doyle P. A. , Adler Laszlo
Published: October 2005

In an attempt to invert ultrasonic scattering data for the characterization of cracks, a theory has been formulated [P. A. Doyle, J. Phys. D: Appl. Phys. 13, 163–77 (1980)] which considers the caustic pattern created by diffraction from the crack edge. Model experiments were carried out to observe acoustical caustics in the shadow of obstacles, using a 250-μm-diam miniature probe as a detector. Qualitative agreement has been obtained between theory and experiment. [This work has been supported by the Defense Advanced Research Projects Agency.]
Cochlear tuning may reflect tectorial membrane resonance
Authors: Zwislocki J. J. , Kletsky E. J.
Published: October 2005

Until recently it was not possible to account accurately for the basilar-membrane amplitude and phase data of Rhode (1971). This may be so because the basilar membrane with its attachments was treated as a simple mechanical system consisting of stiffness, mass, and resistance distributed along the cochlea. When it is assumed instead that the mass of the tectorial membrane is attached elastically to the basilar membrane so that it can resonate in the radial mode at a frequency slightly above the measured best frequency, the resulting load on the basilar membrane leads to an amplitude and phase pattern in agreement with Rhode's. The effect was demonstrated on simple mechanical and network models. The latter yielded simultaneously a shear motion between the tectorial membrane and the reticular lamina, which paralleled neural tuning curves. The shear motion is generally regarded as the adequate stimulus for the hair cells. Construction of the tuning curves included a variable damping consistent with Rhode's results. Constant damping decreased the high-frequency slope of the tuning curves in agreement with experimental results on pathological cochleas. [Work supported by NIH.]
Adaptation in auditory nerve fibers: Interaction between rapid and short-term processes
Authors: Smith Robert L. , Brachman Michael L.
Published: October 2005

In response to changes in sound intensity, auditory-nerve fibers appear to exhibit both rapid and short-term adaptation. The former produces a rapid change in firing rate during the first few milliseconds of response, while the latter causes a change over tens of milliseconds. Both processes have similar effects on the shape of PST histograms. However, they differ in the quantitative relationship they produce between onset and steady-state responses [R. L. Smith and M. L. Brachman, Brain Res. 184, 499–505 (1980)] and in the way they are influenced by prior adaptation [M. L. Brachman et al., J. Acoust. Soc. Am. Suppl. 1 65, S83 (1979)]. A phenomenological model has been developed to account for the experimental results. According to the model, rapid adaptation reflects the depletion of a substance, possibly synaptic transmitter. The substance is stored in a group of mutually independent regions, and flow from a given region occurs only when stimulus intensity exceeds an appropriate level. Substance is replenished from a more slowly depleted reservoir which produces short-term adaptation. The reservoir is replenished from a fixed concentration which determines the steady-state response. [Work supported by NSF and NIH.]
Temporal constraints on anticipatory coarticulation
Authors: Gelfer Carole E. , Harris Katherine S. , Hilt Gary
Published: October 2005

It is the claim of some recent models of speech production that the temporal execution of segmental gestures is intrinsic to the motor program, and that these gestures are time-locked to the segments they characterize. Thus, their acoustic consequences should occur at fixed intervals relative to both the articulatory and acoustic onsets of upcoming phones, irrespective of the number of intervening segments. We therefore hypothesize that, in V1CnV2 utterances, where Cn is /s♯/, /st♯/, or/st♯st/, and V1 and V2 are alternatively either /i/ or /u/, the shorter the consonant string the sooner we would observe the influence of V2 on the preceding friction. Token waveforms were aligned to the offset of V1 and spectrum analyzed. Individual spectra were then computer averaged for each utterance type, thereby increasing the likelihood of observing true resonances within the friction. Preliminary results support our hypothesis and suggest that coarticulatory effects are indeed temporally bound to the acoustic realization of upcoming phones. [Work supported by NINCDS and BRS grants.]
Exploring the information support for speech
Authors: Kelso J. A. Scott , Tuller Betty
Published: October 2005

A well-established feature of speech production is that talkers faced with both anticipated and unanticipated perturbations can spontaneously adjust the movement patterns of articulators such that the acoustic output remains relatively undistorted. Less clear is the nature of the underlying mechanism(s) involved. In this study we examined the production of static vowels and vowels embedded in a dynamic speech context in five subjects under normal conditions and a combined condition in which (a) the mandible was fixed via a biteblock, (b) proprioceptive information was reduced via bilateral anaesthetization of the temperomandibular joint, (c) tactile information from oral mucosa was reduced by extensive application of topical anaesthetic, and (d) auditory information was masked by white noise. Analysis of formant patterns revealed minimal distortion of the speech signal under the combined condition. These findings are unfavorable for a predictive simulation model which requires reliable peripheral information (Lindblom et al., 1979) and more in line with recent work suggesting that movement goals may be achieved by muscle collectives that behave qualitatively similar to a nonlinear vibratory system (Fowler et al., 1980; Kelso et al., 1980). [Work supported by NINCDS and BRSG.]
Using the acoustic signal to make inferences about place and duration of tongue-palate contact
Authors: Price P. J.
Published: October 2005

Productions by four native speakers of American English of /t/ and /d/ in various intervocalic contexts were examined. Closure duration was measured from the acoustic signal (using both waveform and spectral analysis) and from dynamic palatography data. Place of contact (mean of front-most and rear-most contact) was observed from the palatographic signal; formant-frequency measurements (F2, F3, F4) in the closure interval were made. Measurements were averaged over six productions of each stimulus by each talker. Duration measurements by the two techniques correlated well, except (as expected) in instances in which the second vowel had a glottal onset, in which case the durations of low amplitude in the acoustic waveform were longer than the durations of the tongue-palate closure measured palatographically. Place of contact correlated best with F3 measurements. Normalization across talkers was achieved by dividing each F3 measurement by the talker's mean F2. [Work supported by NICHD.
Sound insulation ratings—the STC revisited
Authors: Northwood T. D.
Published: October 2005

About twenty years ago, building authorities and their acoustical experts were faced with a confusing variety of schemes for rating the sound insulation of walls and floors. There was need for a definitive rating system that would digest the 16 transmission loss values that characterize a partition and produce a single number that would describe its sound insulation performance, especially in respect to multi-family dwellings. Two standards committees, ISO/TC 43 and ASTM E6 (now E33), began more or less together to develop a new improved rating system to fill this need. The product of these labors was what is known in North America as the ASTM sound transmission class (STC). This rating system was so successful that it was almost universally adopted—even in applications for which it was not intended. Despite the apparent success there is now increasing awareness of imperfections in the system. These are examined, in light of accumulated data and experience, to see whether the system could or should be improved by certain minor changes.
Distortion of finite amplitude ultrasound in tissue
Authors: Haran Michael E. , Cook Bill D.
Published: October 2005

A form of Burgers' equation is used to derive an algorithm for calculation of harmonic content versus range for a plane sound wave of finite amplitude propagating in a lossy, dispersionless medium. Amniotic fluid, liver, cerebrospinal fluid, and blood plasma are investigated using common biomedical frequencies and intensities. It is shown that shock front formation is possible in tissue having a sufficiently low infinitesimal amplitude attenuation coefficient. A criterion is given to determine if shock front formation is possible in any tissue for a given initial sound frequency and intensity. The implications of this distortion include effects on imaging capabilities of diagnostic systems, measurement of attenuation coefficients of tissues, and biological effects mechanisms.
Nonlinear acoustics and biological media
Authors: Law W. K. , Frizzell L. A. , Dunn F.
Published: October 2005

The propagation of nonlinear ultrasonic waves in aqueous solutions of biological macromolecules (tissue models) has been studied by making measurements of the fundamental at the sound source and the second harmonic as a function of distance from the source. These studies show that the nonlinearity parameter B/A for bovine serum albumin and hemoglobin solutions increases nearly linearly with concentration from 5.2 for water to 7.3 for a 40% solution, suggesting that the solution becomes more nonlinear as the spacing distance between molecules decreases. Solutions of dextran molecules also have been studied from the monomer to a molecular weight of 2 000 000 Daltons showing that the nonlinearity parameter, for fixed concentration, is relatively insensitive to molecular weight. Measurements have also been made in whole mammalian blood which exhibits a nonlinearity parameter in proportion to its dry weight which consists largely of protein. These findings suggest that details of nonlinear acoustic propagation in living systems may contribute to further improvement in clinical diagnostic procedures. [This research was supported by a grant from the National Science Foundation.]
Sampling techniques for the measurement of noise levels from building construction sites
Authors: Utley W. A.
Published: October 2005

The Control of Pollution Act gave to local authorities in the UK new powers to control noise from construction sites. These include the possibility of setting noise limits. When monitoring noise emission in order to check compliance with limits, savings in manpower and equipment may be made by using sampling techniques. Two techniques for estimating the measured daily Leq from measurements taken during part of the day were investigated. The first technique involved sampling on a regular basis (e.g., 5 min/h) throughout the whole day while the second technique involved the use of a single continuous sample. The errors associated with the two techniques were determined by measuring the noise from ten building construction sites. At some of the sites measurements were made at different stages in the construction process and this resulted in a total of 21 days of measurement. It was found that by sampling for five minutes in every hour the daily Leq could be estimated within ±2.5 dB(A). To obtain similar accuracy with the single-sample technique the sample would have to be just over 60-min long.
Organizing the lexicon for recognition
Authors: Jakimik Jola , Hunnicutt Sheri
Published: October 2005

In this paper we discuss several aspects of the organization of a lexicon for the purpose of recognizing spoken words. We are interested in what a listener (human or computer) needs to know about a word in order to distinguish it from other words. We consider how words may be organized (or “indexed”) in the lexicon so that appropriate candidates for recognition are accessed from partial information, and how each word may be specified. (These features of a lexion define the dimensions of perceptual similarity among words, which determine misperceptions, for example.) We evaluate some likely indexing properties and lexical representations; for example, we consider indexing by stressed vowels, and lexical representation in terms of consonant and vowel classes.
Computational cost of DP algorithms in speech recognition
Authors: Waibel A. , Krishnan N. , Reddy R.
Published: October 2005

In this study we present the models of computation of several search algorithms for isolated word recognition. These search techniques considered include variants of the classical dynamic programming, variants of branch-and-bound search technique and variants of the beam search technique (as implemented in the Harpy system). We show that depending on the choice of the technique and related parameters, one can achieve more than an order of magnitude improvement in speed without any loss of accuracy.
An architecture of an MOS-LSI speech recognition system using dynamic programming
Authors: Murveit H. , Lowy M. , Brodersen R. W.
Published: October 2005

In the past several years, a number of very accurate, isolated word speech recognition systems based on dynamic programming techniques have been designed and tested. However, as these techniques are computationally intensive, commercial systems using dynamic time warping have been costly. We have designed an architecture which exploits the capabilities of custom MOS-LSI designs to implement a complete speech recognition system. This system would operate in real time using dynamic time warping, yet it would only require 4–5 integrated circuits for a moderate (50–200 word) vocabulary. This system is designed to be expandable so that larger vocabularies can be used by including additional IC's in parallel with the others. The integrated circuits which are required are two custom-designed chips, a memory IC, and a low-performance microcomputer for overall control. The custom chips include a front end processor for spectral analysis (currently a switched-capacitor filter bank) with an endpoint detector, and an IC to implement the dynamic programming algorithm. The architecture of the custom chips has been defined so that adequate performance can be obtained from a standard MOS process. A connected speech recognition algorithm that is based on the use of the above IC's has been developed and will be described. It requires additional processing in the low-speed microcomputer to perform a second level of dynamic programming.
An engineering view of middle ear surgery
Authors: Killion Mead C. , Clemis Jack D.
Published: October 2005

As evidenced in the preceeding papers, the function of the normal middle ear is now reasonably well defined. This provides the mathematical basis for an estimate of the acoustical effects of middle ear surgeries. By using a model based on a combination of Bauer's [J. Acoust. Soc. Am. 42, 1095–1097 (1967)] equivalent circuit to account for head diffraction, Zuercher's (J. Acoust. Soc. Am. Suppl. 1 62, S56(A) [1977]) approximations for acoustic tubes to model the pinna, concha, and earcanal, and Shaw's [J. Acoust. Soc. Am. Suppl. 1 62, S12(A) (1977)] equivalent circuit to model the normal middle ear, we obtained excellent agreement with available data on the normal sound-field-to-oval-window transformation in humans. By altering appropriate sections of the model, we calculated the expected effects of Type IV tympanoplasty, fenestration, etc., on the sound pressure delivered to the oval window. Our results are in general agreement with the observations of Goode et al. [Ann. Oto. Rhyn. Laryngol. 86, 441–450 (1977)]. New experimental results, and their implications, will be discussed. The estimated quality of sound transmission resulting from some common middle-ear alterations will be demonstrated with tape-recorded examples obtained from electrical analogs.
Path integrals and acoustic fluctuations near caustics
Authors: Ryan F. J.
Published: October 2005

The JASON group (cf. Flatté et al., Sound Transmission Through a Fluctuating Ocean, Cambridge University Press, 1979) have developed a theory of acoustic signal propagation through a fluctuating ocean. Ray theory was used to model the deterministic background sound channel and singularities arise when caustics are present in the geometrical optics field. An extension to the JASON theory will be described which treats caustics by means of generalized diffraction integrals and results from catastrophe theory. The Feynman path integral formalism is extended to include multiple coalescing stationary phase points and yields finite results near caustics. The effect of medium fluctuations on the stability of caustics will be discussed, and results for commonly occurring catastrophes (caustics), such as the fold and cusp, will be shown.
Ray-mode model for ducted precursors
Authors: Spofford C. W. , Keenan R. E.
Published: October 2005

In a surface-duct environment a fraction of the ducted energy continuously leaks from the duct into the deeper water. Under certain conditions this diffracted energy returns to the duct creating arrivals which lag the ducted arrival and precede the normal deep-water arrivals. These arrivals have been called ducted precursors and can be comparable in magnitude to both the purely ducted and deep-water arrivals. This paper presents a model that has been developed to predict the amplitudes and arrival times of the ducted precursors. The model combines a normal or virtual-mode description for the ducted energy (including all diffraction effects) with a ray treatment for the propagation of the leakage fields. The conditions under which the ducted precursors are significant are discussed. Comparisons of the model predictions with data and with a full-wave model are presented in a companion paper. [Work supported by NUSC/NLL and NORDA Code 500.]
Acoustical measurements in the UNI-Dome compared with other air-supported fabric structures
Authors: Wyerman Barry R.
Published: October 2005

Reverberation times and ambient sound levels were measured in the UNI-Dome Multi-purpose Coliseum at the University of Northern Iowa. This air supported fabric structure has an inner liner of fabric suspended under 67% of its roof surface. The liner was primarily intended for thermal control but also provides acoustical control for the space. Reverberation times in the UNI-Dome are compared with reverberation times for several other air supported fabric structures having different types of acoustical treatment. Ambient sound levels and early reflected echoes are also compared for these spaces. The results demonstrated that when material is added to the roof surface of a fabric structure to improve its thermal performance, there is a corresponding improvement in its acoustical performance.
Standing waves in a flute
Authors: Strong William J. , Silk Ron , Fletcher Neville H.
Published: October 2005

Standing wave patterns for pressure were calculated and measured for two alternate A6 fingerings on a flute. For a fingering with the D♯ key open the calculated pressure distribution agreed well with a similar result from Coltman [J. Acoust. Soc. Am. 65, 499–506 (1979)] and with probe tube measurements made on the instrument when excited sinusoidally at resonance. For a fingering with the D♯ key closed the agreement among pressure distributions was much poorer. These results will be discussed in terms of the sensitivity of impedance matching in the open hole part of the tube as a function of frequency. [Work supported in part by Australian-American Educational Foundation.]
Multichannel digital synthesizer design using bit-slice microprocessor architecture
Authors: McKay Blair D. , Wills Barry L.
Published: October 2005

Real-time synthesis of complex audio waveforms is required in a number of computer music applications. Digital synthesizers can achieve the desired complexity by additive means where multiple oscillators per voice are employed, each with controlled frequency and amplitude envelopes. In order to meet the real-time requirements and also provide perceptually acceptable output signals a new multichannel synthesizer using bit-slice technology has been designed and constructed. Concomitant control software, down-line loaded from a supervising microcomputer, defines the number of active channels, their groupings (per voice), the sampling rate of each channel, and its particular amplitude and frequency control scheme. Parameters in the synthesizer are subsequently updated by the supervising microcomputer to create the desired audio outputs in real time. The versatility permitted by changing the control program together with improvements over other reported designs in signal-to-noise ratio, dynamic range and frequency resolution make this approach attractive for several applications.
Effect of continuous traffic noise on percentage of deep sleep, waking, and sleep latency
Authors: Thiessen G. J. , Lapointe A. C.
Published: October 2005

When subjected to alternating quiet nights (32 dB) and noisy nights (equivalent levels of 47 dB) a group of 12 subjects showed an average increase in the fraction of deep sleep of about 2.5% resulting from the traffic noise. Another group of 12 subjects whose noise nights were at 60 dB had an average of 4.8% increase in deep sleep during these nights. The number of wakings, however, also increased for both groups but, as was found before, this adapted rapidly with the number of nights. The latency of sleep onset does not appear to be affected by the traffic noise. Latency of sleep onset and waking both show appreciable “laboratory effect” which takes longer to disappear than the one or two nights usually assumed.
Transformer noise propagation and measurement
Authors: Ying S. P. , McGaughey J. W.
Published: October 2005

In a homogeneous atmosphere, the attenuation of transformer noise results from geometrical spreading of its sound power and excess attenuations due to atmospherical absorption, barriers, and other factors. However, an inhomogeneous atmosphere due to winds and temperature gradients has a significant effect on the nearly monotonic transformer noise in the community, particularly at night. These effects become more evident under certain topographic conditions such as hills which act as acoustical barriers. This paper discusses these temperature inversion, wind, and topographic effects on environmental noise of electric power substations. When the total output power of a linear system is stimulated by its statistically independent multiple sources, the coherence function can be used to resolve the total power into individual output power of each source. This technique was applied to a converter substation to characterize the transformer noise from other noises including the wind noise. The coherence function and coherent output power were obtained from a dual channel fast Fourier transform (FFT) analyzer. The substation noise in the community was also analyzed by the FFT analyzer to obtain the sound-pressure level of the noise at long distances from correlation with the results of coherence measurements.
The role of acoustic tube resonances in the radiation of sound from circumferentially ribbed truck tires
Authors: Donavan Paul R.
Published: October 2005

While in contact with the pavement surface, the grooves of circumferentially ribbed tires form tubes open at both the leading and trailing edges of the tire contact patch. These tubes efficiently radiale sound at the fundamental resonant frequency, corresponding to an acoustic wavelength equal to one half of the tube length, and at the higher harmonic frequencies. This behavior was studied with acoustic intensity measurements made alongside a moving straight rib (HCR) truck tire using the technique described in a previous presentation [L. J. Oswald and P. R. Donavan, J. Acoust. Soc. Am. Suppl. 1, 67, S71 (1980)]. These data show a 3 to 7 dB reduction from 500 to 2500 Hz in the narrow-band acoustic intensity spectrum when the resonant-tube radiation is eliminated with open cell foam placed in the grooves. Further, consistent with the dipolelike radiation from the tube ends occurring at the odd-numbered tube harmonics, distinct nulls in the acoustic intensity were measured alongside the center of the contact patch at these frequencies. The influence of resonant tube radiation is also discussed for commercial wavy rib truck and passenger car tires.
Wind farm noise
Authors: Tocci Gregory C. , Koning Brion G.
Published: October 2005

Arrays of small wind turbines, recently coined as “wind farms”, offer several advantages over single, larger wind turbines producing the same electrical power. Noise source characteristics of wind farms are also different from those associated with a single wind turbine. One-third octave band noise measurements from 2 Hz to 10 kHz have been made and will be compared to measurements of noise produced by a single, large wind turbine. [J. R. Balombin, Technical Memorandum 81486.]