bluuebunny/crossref_metadata_2025 huggingface dataset:
A measurable result of bi-tri octave plate tuning
Authors: Hutchins Carleen M.
Published: October 2005

Many of the finest violins and violas exhibit a special quality, namely that the four quadrants of both top and back, when tapped lightly, can be heard to have approximately the same pitch. In an experiment with three violas made on the same pattern and with very similar wood, the one with bi-tri octave tuning (modes 2 and 5 at matching octaves in both top and back plates and mode 1 in the top an octave below mode 2) was found to have the above condition. The other two, with different conditions of their free plate resonances, did not. An electronic measurement of the eight quadrants in these violas, four in the top and four in the back where one would ordinarily tap, showed that the lowest two resonance peaks in each of the eight quadrants were very similar, for the bi-tri octave plate tuned viola. This was not the case in the other two which were judged by expert players to have considerably less good tone and playing qualities. These findings will be charted and their implications discussed.
Prediction of a radiation field of a spherical sound source with a local responsive surface from measurements of diffraction field characteristics
Authors: Tsukernikov Ilja E.
Published: October 2005

A method is offered for the calculation of radiation field using measurements of sound pressure and the vibration velocity normal component on a spherical surface surrounding the sound source and setting it off from extraneous sound sources. The total diffraction field is presented as a superposition of the spead radiation field and the field to be scattered by the source surface (a direct field) as well as standing waves describing a reflected field and a field of extraneous sources. The scattering properties of the emitting sphere are given with the help of modal impedances. The field components are represented as an expansion in terms of the spherical harmonics. The expansion coefficients for the scattered field pressure on the source surface are calculated by solving of the integral equation of the second kind which is derived from the discontinuity properties of the Helmholtz integral on the boundary surface and from the impedance boundary condition. The radiation field is found as the difference of the direct field and the scattered field presented with the help of the Helmholtz integrals calculated over the measured and emitted surfaces. The method is illustrated by calculating the radiation field of a sphere pulsating with the prescribed velocity in the space bounded by the perfect reflecting spherical surface.
Hearing threshold levels for comparison purposes
Authors: Passchier-Vermeer Willy
Published: October 2005

To determine noise-induced hearing loss in otologically unselected populations exposed to occupational and/or nonoccupational noise, hearing threshold levels of these populations should be compared with those of a comparison population. To that aim, based on two Netherlands databases, a calculation scheme for hearing threshold levels of otologically unselected comparison populations has been developed. In this scheme, median hearing thresholds are taken equal to 2 dB plus the median hearing threshold levels given in database ISO A [ISO 7029 and Annex A of ISO 1999:1990 (E)] for frequencies between 500 and 6000 Hz. The hearing thresholds exceeded in 90% of the comparison population are equal to those in database ISO A, and the hearing thresholds levels exceeded in 10% of the comparison population are 6 dB plus those given in database ISO A. The calculation scheme fits very well the data of otologically unscreened male comparison populations in Germany [Irion (1983); Pfeiffer (1985)], France [Thierry (1988)], Hong Kong [Evans (1982)], Sweden [Hansson (1992)], and a black population in the USA [Driscoll and Royster (1984)].
Hallowell Davis and evoked potential audiometry
Authors: Picton Terence W.
Published: October 2005

While studying the human electroencephalogram, Hallowell and Pauline Davis made the first recordings of the human auditory evoked potentials. In 1939 they published the founding papers for evoked potential audiometry: One by Pauline on recordings during wakefulness and a second by Hallowell on recordings during sleep. Although the possible audiometric usefulness of these responses was recognized, it was not until the 1960’s that new averaging computers made their recording sufficiently objective for clinical use. In the 60’s and early 70’s, Hallowell and his colleagues then produced a series of definitive papers on the acoustical characteristics and clinical usefulness of the auditory ‘‘vertex potential.’’ While studying the effects of attention on this response, Hallowell made the first recordings of the P300 wave that is related to human information processing. For the last 15 years of his life, Hallowell put together techniques for evaluating frequency-specific thresholds in infants and young children with the auditory brain-stem response, proposing special stimuli (the 2-1-2 toneburst) and special response measurements (the SN10 wave). Hallowell Davis has been considered the ‘‘father of evoked potential audiometry’’: He was there at the beginning and continuously assisted the development of the field with careful research and insightful review.
Limits of exposure to high-intensity impulse noise with a 1.5-ms A duration
Authors: Patterson James H. , Johnson Daniel L.
Published: October 2005

Over the past several years, the U.S. Army Medical Research and Development Command has sponsored a series of studies to determine the human tolerance limits of exposure to high-intensity free-field impulse noise. These studies have been conducted at the Blast Overpressure Test Site in Albuquerque, NM, by EG&G. The results of these studies for impulses with A-durations of 0.8 and 2.9 ms have been reported previously. In the latest study, human volunteers have been exposed to intensities ranging from 173 to 193 dB SPL with an A duration of 1.5 ms. The number of impulses per exposure was varied from 6 to 100. Hearing protection was worn during all exposures. For 6 impulses and 120 impulses, the safe upper intensity limit was approximately 187 dB peak SPL. For 25 to 100 impulses, the limit was approximately 184 dB SPL. [Work supported by U.S. Army Medical Research & Development Command, Contract DAMD17-88-C-8141.] In the conduct of research where humans were the subjects, the investigator(s) adhered to the policies regarding the protection of human subjects as prescribed by 45 CFR 46 (Protection of Human Subjects).
Using acoustic impulses to identify a buried nonmetallic object
Authors: Don Charles G. , Rogers Andrew J.
Published: October 2005

Metal detectors are ineffective in locating shallowly buried plastic objects such as water pipes or land mines. However, the acoustic reflection from such objects has the potential to locate and identify the body. If an impulse is utilized, the ground reflection is followed by one from the object, the delay depending on its depth below the surface. A newly developed probe compares signals from two microphones located on either side of a very reproducible impulse source. When one microphone is over a buried object and the other over a homogeneous matrix, there are subtle differences between the reflected signals, as the probe is effectively an edge detector. Variations in the surface flatness and the matrix homogeneity cause unwanted noise in the difference signal, which can be partially eliminated by correlation techniques. The size and location of the object is determined by traversing the microphone probe over the surface while its depth be deduced by setting different time windows. Trial results have distinguished between plastic strips, disks, and rocks buried between 4 and 15 cm into a matrix of small pebbles. Advantages of extending the technique to three or four microphones will be described.
The coordinate system for jaw movement control
Authors: Vatikiotis-Bateson Eric , Gribble Paul , Ostry David
Published: October 2005

Previously, it was reported that, when 3-D jaw motion during speech is decomposed into its three rotation and three translation components, it consists primarily of rotation and translation within the midsagittal plane [E. Vatikiotis-Bateson and D. J. Ostry, J. Acoust. Soc. Am. 92, 2391(A) (1992)]. Although small in magnitude, two nonsagittal components, roll and yaw, also varied consistently with phonetic context. In this paper, it is shown that the behavior of individual jaw motion components depends in part on the choice of coordinate system orientation. In particular, the use of the occlusal bite plane to orient the jaw may not be appropriate for characterizing the active components of jaw motion during speech. For example, when orientation of the coordinate system is rotated 15–20 deg down from the occlusal plane, the roll component is eliminated. Whether or not the frame or reference for jaw motion is function-specific or purely anatomical is addressed using data from a new study comparing mastication and speech.
A case study into the aerodynamics of consonant production in running speech of children
Authors: Koenig Laura L. , McGowan Richard S.
Published: October 2005

Phonetic studies of children’s speech have shown that many aspects of speech production may continue to develop well past the age at which the basic set of phonological distinctions is established. Until recently, most such investigations have been transcriptional or acoustic. In the present study, a pneumotachograph was used to record airflow during running speech in one child, age 5;8. It is known from work on adults that airflow from the mouth reflects the relative timing of oral and laryngeal movements in /VCV/ sequences. The data from the present subject show extensive variability in the relative timing and magnitude of oral-laryngeal movements for many /VCV/’s. As a result, fully adult-like differences in airflow and f0 as a function of consonant voicing are not evident. In this respect results are consistent with developmental studies of VOT and the effects on f0 of consonant voicing. The aerodynamic data add detail to our understanding of how children acquire laryngeal control of consonants. [Work supported by NIH.]
Synthesis of consonant sequences using a Klatt synthesizer with higher-level control
Authors: Bickley Corine , Stevens Kenneth N. , Williams David R.
Published: October 2005

The use of higher-level (HL), quasi-articulatory parameters to control a formant-based speech synthesizer has the potential advantage of greatly simplifying the array of parameters needed to synthesize consonants. The principal parameters in this array are the time-varying cross-sectional areas of the constriction formed by the primary articulator, and of the orifice formed by the secondary articulator, i.e., the glottal of the velopharyngeal port. This paper describes rule-driven procedures for synthesizing consonant sequences that require changes in the primary articulator or movements of the secondary articulator. Examples include: (1) clusters such as /pl/ or /tw/ where the HL parameters are automatically mapped into frication noise in the coarticulated liquid or glide; (2) nasal-obstruent sequences in which velopharyngeal closure automatically results in an intraoral pressure increase; (3) sequences of two stop consonants in which the two articulatory closures and releases are manifested acoustically in different ways depending on their timing and on the glottal adjustments; and (4) fricative-stop and stop-fricative sequences in which the stop may have an influence on the fricative noise. Variants created through simple adjustment of parameter timing illustrate the efficiency and flexibility of the procedures. [Work supported in part by NIDCD.]
Laser-induced underwater acoustic source for remote sensing of sea floor
Authors: Egerev S. V. , Ivakin A. N. , Ovchinnikov O. B. , Pashin A. E.
Published: October 2005

An underwater near-surface optoacoustic source was used for remote sea floor sensing. The laser pulse of 5- to 10-μs width irradiates a spot at the water surface. The burst of surface pressure generates a hydroacoustic pulse is somewhat like a marine mammal’s echo-location pulse. The pressure level at a distance of 1 m from the surface is about 0.1 MPa. The total acoustic energy transmitted to the ocean can amount to 1–10 J or more. Explosive laser-induced underwater acoustic source (LIUAS) are most significant for remote sea-bed sensing. (1) The signal is of ultrawide band character (1–100 kHz), hence the single shot record produces a set of narrow-band reverberation responses. (2) Scattering coefficient versus angle of incidence can be extracted. (3) High spatial resolution of the LIUAS signal. Full scale experiments were conducted in the shallow water of the Black Sea. An appropriate sea-bed scattering model was developed taking into account sound scattering by smooth large-scale (Kirchhoff) roughness of bottom relief and by anisotropic volume inhomogeneities of the subsurface sediment layer. Comparison of experimental and calculated data shows that the sea-bed reverberation was of a volume character rather than surface.
Interaction of three different types of maskers
Authors: Jesteadt Walt , Kessler Christina J. , Neff Donna L.
Published: October 2005

Models of additivity of masking typically assume that the same compressive nonlinear transformation is applied to all individual masking effects before they combine. The results for combinations of three different types of maskers are not easily predicted, however, if some pairwise combinations of maskers show more compressive effects than others. To explore this question, adaptive thresholds were obtained for a 24-ms, 1600-Hz signal in the presence of three different maskers presented alone and in various combinations: (1) a 400-ms broadband noise simultaneous masker; (2) a 400-ms octave-band noise simultaneous masker centered at 500 Hz, and (3) a 296-ms, 1600-Hz forward masker with a 4-ms signal delay. The broadband noise was presented at 10 dB No; the other two maskers were presented at seven levels that produced a range of masked thresholds 15 dB above and below that for the broadband noise. Results will be discussed in terms of an associative model in which the effects of two maskers combine and the pairwise effect then combines with the third masker. This model could be applied to data for listeners with sensorineural hearing loss, where the hearing loss is treated as a masking effect. [Work supported by NIDCD.]
Progress report on the continuing activity on the ASA’s role in noise and its control
Authors: Hoover Robert M.
Published: October 2005

A discussion meeting is being sponsored by the Technical Committee on Noise to review progress made to date on the actions initiated by the Technical Committee on Noise at the Denver 1993 meeting to increase the role of the ASA in noise and its control. Members of the steering committee will each review the specific activities undertaken in the areas of education, collaboration with other societies, increasing public awareness of noise, and the establishment of a task force to determine feasibility of establishing an ASA clearinghouse on noise.
Review of theoretical and experimental aspects of acoustical modeling of engine exhaust systems
Authors: Sridhara B. S. , Crocker Malcolm J.
Published: October 2005

In an internal combustion engine, the engine is the noise source and the exhaust pipe is the main transmitter of noise to the atmosphere. Mufflers are often used to reduce the engine noise radiated from the exhaust pipe. To optimize a muffler design, a series of experiments can be conducted using various mufflers installed in the exhaust system. For each exhaust system arrangement, the radiated sound pressure can be measured. However, this is not a very efficient approach and there is no guarantee that an optimum arrangement is attained. A second approach is to develop a scheme involving only a few measurements, which can be used to predict the radiated sound pressure at a specified distance from the open end of the exhaust pipe. In the research work reported here, the engine exhaust system was modeled as a lumped source–muffler–termination system. An expression for the predicted sound pressure level was derived in terms of the source and termination impedances, and the muffler geometry. The velocity source and monopole radiation models were used for the source and the open end of the exhaust pipe, respectively. Four-pole parameters were used to relate the acoustical properties at different cross sections of the muffler and the exhaust pipe.
Analysis of a bottom backscattering data set: Evidence of sub-bottom volume scattering
Authors: Holland Charles W. , Neumann Peter D.
Published: October 2005

Low-frequency (under 1 kHz), low-grazing angle (under 30°) bottom backscatter data from the Messina Cone in the Ionian Sea are analyzed. Core data and bottom loss data both indicate that the sediment impedance at the water–sediment interface is too small to attribute the observed backscatter to rough surface scattering. It is hypothesized that the scattering arises from lateral discontinuities of turbidite layers in the sub-bottom volume. A self-consistent acoustic and geoacoustic model for treating such sub-bottom volume inhomogeneities is proposed and compared with the measured data. The model appears to successfully predict the grazing angle, frequency, and pulse length dependence of the measured data. The pulse length dependence of the measured data is hypothesized to arise from the lateral size distribution of the discontinuities. Thus the pulse length dependence of bottom scattering could be a useful measure of the lateral length scales of sub-bottom volume inhomogeneities. [Work supported by ONR/AEAS.]
Waves on panel structures from turbulent boundary layer excitations
Authors: Maestrello L.
Published: October 2005

Response and acoustic radiation measurements from aircraft-type panels forced to vibrate by turbulent boundary layer flow are made in a quiet air duct facility and in a wind tunnel. Two types of aluminum structure are used: a newly developed panel with irregular, protruding, varying-thickness wedges at the upstream and downstream boundaries (fractal-type geometry) and a standard aircraft fuselage sidewall panel. Both panels have the same mass and exposed surface area to the flow. The new panel boundary has an extended perimeter with a gradual change in mass stiffness toward the center. The objective is to control the radiated acoustic pressure field. This is achieved by controlling the convective waves reflecting at the upstream and downstream boundaries of the panel. The geometry of the boundary is designed to induce a mismatch and randomness in wave motion along the direction of flow, resulting in significant attenuation of the amplitude of the incident and reflected waves.
Vibrations in violins with tuned fingerboards: A case study of instrument feedback
Authors: Jansson Erik V. , Askenfelt Anders
Published: October 2005

All traditional musical instruments vibrate more or less during playing. These vibrations serve as a silent feedback from the instrument to the musician, and the feedback is likely to be an important component of the instrument response. Work has been done to study if an enhanced vibration level in the violin is perceived as favorable by the musician, and if such a change results in a change in playing. The vibration level in the instrument was varied by tuning a fingerboard resonance in relation to the Helmholtz’s resonance (A0). The level was measured prior to and after the tuning of the fingerboard, using two ‘‘types’’ of violinists; a PC-controlled bowing machine and professional violin players, respectively. The quality of the instrument as judged by the musicians with and without tuned fingerboard, respectively, gives an estimation of the degree of feedback from instrument to player. [Work supported by the Swedish Council for Research in the Humanities and Social Sciences.]
Within- and across-channel processes in modulation detection interference
Authors: Mendoza L. , Hall J. W. , Grose J. H.
Published: October 2005

Modulation detection interference (MDI) was measured using sinusoidally modulated (10 Hz) tones. In order to assess the relative influences of within- and across-channel processes, the carrier frequency of the target was held constant at 993 Hz, while the carrier frequency of the interferer was either 450, 596, 788, 1250, 1654, 2188, 2895, or 3828 Hz. The interferer carrier was presented either to the same ear as the target carrier, or to the ear contralateral to the target. In addition, the interferer carrier was either gated synchronously with the target carrier, or present continuously. Although individual differences were observed, substantial MDI occurred in the contralateral as well as the monaural gated-interferer conditions. While most subjects showed increasing interference as the monaural-interferer carrier frequency approached the carrier frequency of the target, some subjects also demonstrated increasing MDI as the interferer carrier approached the target carrier in the gated contralateral-interferer condition.
Age perception of speakers of isolated words and sentences
Authors: Ralston James V. , Tse Mary , Campbell Emily R. , Wright Alison D. , Fisher Tracey L. , McCall Michael
Published: October 2005

Ten males in each of three age groups (M=12 years, M=22 years, M=74 years, respectively) were recorded while reading lists of 16 words and 16 sentences. The words and sentences were digitized, segmented, and saved on disk. In one experiment, a sample of the words was presented in random order to listeners who judged the age of the speakers. Listeners overestimated the ages of the young voices by 1 year, overestimated the age of the college-age voices by about 9 years, and underestimated the age of the elder voices by almost 20 years. An assimilation effect was also observed, such that age estimates of voices were shifted toward the ages of speakers on the previous trial. Finally, there was a significant correlation between age estimates and the duration of the words. A second experiment utilizing the same methods with isolated sentences revealed smaller estimation errors and smaller assimilation effects. These results, as well as those from ongoing experiments, will be discussed in light of their basic and applied significance.
Understanding of time-compressed speech in older adults
Authors: Letowski Tomasz R. , Poch Nancy E.
Published: October 2005

Fifteen subjects, ages 60 to 74 years, participated in a study to assess the role of discard interval length in the understanding of time-compressed speech. Fixed discard intervals previously available in commercial equipment such as the Lexicon Varispeech II have allowed changes in rate of compression only. In the present study, compression rate was held constant at 50% and discard interval length was varied in 20-ms steps from 35 ms, which is within the usual range of discard intervals, to 115 ms. Operationally, this meant that a discard interval of 115 ms resulted in deleting 50% of every 230-ms portion of the text. Performance deteriorated gradually until a critical DI was reached beyond which performance dropped sharply. Results are compared to an earlier study of normal hearing young adult subjects [Poch, presented at ASA (November 1992)] using the same speech test materials and time-compression technique. The difference in performance between the two groups is explained in terms of the effects of aging on speed of auditory processing.
Age-related differences in fixed versus roving AX discriminations
Authors: Fox Robert Allen , Balint Christine , McGory Julia , Wall Lida G.
Published: October 2005

The present study examines age-related differences in the discrimination of vowels and consonants (using both AX fixed and roving paradigms). Two groups of listeners—including young adults (mean age 23.9 yr) and older adults (mean age 67.8 yr)—were required to identify and/or discriminate tokens from either a [i]-[eh] vowel continuum or a [bopen aye]–[dopen aye] consonant continuum. The two groups were matched for auditory sensitivity. As expected, for both groups consonant responses were more ‘‘categorical’’ than were vowel responses. Fixed discrimination was also better than roving discrimination (although the effect was only significant for the consonant stimuli). In terms of age differences, discrimination performance tended to be better for younger listeners in most conditions, although these differences did not reach statistical significance. However, there was a significant age by task paradigm interaction for the consonant stimuli. Although the younger listeners showed significantly poorer discrimination in the roving vs. fixed condition, there was no such difference for the older listeners. Discriminations by older listeners were also more affected by the location of the category boundaries than were those of younger listeners. [Work supported, in part, by the National Institute on Aging Grant No. 5R01 AG08353.]
A developmental study of vowel perception from brief synthetic consonant–vowel syllables
Authors: Ohde Ralph N. , Haley Katarina L. , McMahon Christine W.
Published: October 2005

The purpose of this study was to assess the perceptual role of brief synthetic consonant–vowel syllables as cues for vowels in children and adults. Stop–consonant syllables were synthesized in the context of three vowels, [i, u open aye], with durations of 10, 30, or 46 ms. These syllables were produced with bursts, and contained formant motions and/or formant onset frequencies appropriate for each stop–consonant place of articulation. Eight children at each of five age levels, 5, 6, 7, 9, and 11, and a control group of eight adults were trained to identify the vowel as either /i/, /u/, or /open aye/. The findings showed that children and adults extracted vowel information at a generally high level from stimuli as brief as one glottal pulse (together with initial burst). However, significant effects were found for age, vowel, duration, and transition type. The age effects manifested that even quantal vowels were not identified in an adult-like manner by young children. The duration and transition-type effects revealed that vowel perception was sometimes better for longer syllables with moving formant transitions. Overall, these perceptual findings indicate that syllable identification is more salient in adults than children. [Work supported by NIH, DC00464.]
Spontaneous adult judgments of infant vowel productions
Authors: Ichijima Tamiko , Lacerda Francisco
Published: October 2005

This study is a pilot investigation of how adult listeners spontaneously perceive the vowel quality in infant utterances. Recordings of two Japanese infants from the Tokyo area were used to generate the stimuli. One infant was recorded every week between 17 to 24 weeks of age. The other infant was recorded twice, at 32 and 78 weeks of age. The sessions lasted for about 1 h and included playing alone, playing with the mother, and eating. The stimuli for the perceptual evaluation were a random sample consisting of 57 utterances, drawn from the pool of noise and interference-free utterances. Four phonetically trained subjects judged tongue height and frontness in a speeded judgment test paradigm. The results are compatible with the data from earlier acoustic studies [Davis and MacNeilage, J. Speech Hear. Res. 33, 16–27 (1990)], using careful phonetic transcription. Japanese infants explore the opening dimension during the earlier period of babbling. Although the data cannot be used to establish the exact point at which front/back differentiation starts to occur, a significant difference was observed between the use of that dimension at 32 and at 78 weeks of age. [Research supported by The Bank of Sweden Tercentenary Foundation, Grant 90-0150.]
A new formulation for scattering from two objects and objects near an interface with application
Authors: Werby M. F.
Published: October 2005

It is usual to employ a Green’s function technique to develop the mathematical framework to describe scattering from two or more objects or objects near a reflecting interface. The method is perforce rather specific and tedious to develop and leads to a form not very susceptible to physical interpretation. In this work a method is demonstrated that enables one to describe scattering from multiple targets or targets near an interface that is (1) independent of the target boundary conditions, (2) independent of the scattering theory for the single scatterer, and (3) that enables one to gain insight in the scattering process that is not manifest in the usual formulations. Then the method is applied to several classes of targets and raise some issues of how the usual theories are implemented that is apparent from this formulation but not apparent in the usual integral equation–Green’s function approach. [Work sponsored by the Naval Research Laboratory 6.1 Program Element 0601153N.]
Inversion of normal incidence backscatter data from gassy sediments
Authors: Kulbago Timothy J. , Gilbert Kenneth E.
Published: October 2005

Simulation studies of normal-incidence backscatter from shallow-water sediments indicate that high-frequency probe signals (f≊30 kHz) cannot easily distinguish between soft gassy sediments and hard nongassy sediments. Much lower frequencies, on the other hand, clearly differentiate between the two cases. An approach is presented here that uses gross structural information from high-frequency probe signals together with inversion of low-frequency data to extract the physical properties of the near-surface sediment. The approach is applied to simulated backscatter data for both gassy and nongassy sediments. Possible experimental tests of the method are described.
Forward and inverse scattering from rough surfaces at low grazing incidence
Authors: Spivack Mark
Published: October 2005

In acoustic wave scattering from rough surfaces at low grazing angles the usual approximations are known to break down. In the forward-scattering regime this case is often treated by the parabolic integral equation method. The scattering of plane waves within this formulation is considered, and effective reflection coefficients are derived for slightly rough surfaces. Of the higher-order statistics, the dependence of the diffuse and specular components upon incident angle is also examined. The problem of surface reconstruction can be expressed in terms of coupled integral equations; it is explained how in the parabolic case these are easily treated. A major problem, however, is backscatter; a nonparabolic approach to this problem for low-grazing angles is described. [Work supported by Smith Institute Research Fellowship.]
Time domain visualizations of the acoustic scattering from two-dimensional (2-D) rough surfaces
Authors: Keiffer Richard S. , Novarini Jorge C. , Norton Guy V.
Published: October 2005

The impulse response of a 2-D rough surface to a point source is calculated via the wedge assemblage (WA) method. Periodic, doubly periodic, and randomly rough 2-D surfaces having both Dirichlet and Neumann boundary conditions are considered. The WA method is used to generate time-evolving visualizations of the scattering process by mapping onto all parts of the scattering surface a color that represents a surface elements contribution to the instantaneous scattered field as measured at the receiver. Successive snapshots of this color-coded spatial mapping of the individual impulse responses are generated and displayed sequentially to form a movie. In addition to the movie, a new tool for the analysis of the scattering process is introduced. This new tool uses the fact that, for the particular surface discretization employed, only four distinct types (directions) of wedge can occur. Because the contributions of the different wedge types to the overall impulse response are readily separated via the WA model, one can study the role of surface curvature in different directions for various scattering geometries. In particular, this unique capability is exploited to gain further insight into the role of out-of-plane scatterers for various geometries. [Work supported by ONR.]
Application of isoperimetric inequalities to the problem of acoustic scattering from irregularly shaped objects
Authors: Palmer David R.
Published: October 2005

It is of general interest to determine the extent that acoustic remote sensing can estimate physical properties of particulates suspended in the ocean. One question that can be asked is how well the concentration of particulates can be determined from measurements of the backscattered acoustic intensity. When it applies, Rayleigh scattering theory provides the relationship between the concentration and the intensity. The assumption is always made in application of the theory that the individual scatterers can be regarded as spheres. While this assumption is intuitively reasonable, it is desirable to have error estimates. In this work, bounds are derived for the error that can occur in mass-concentration estimates due to the spherical-scatterer assumption. These bounds are obtained by using the theory of isoperimetric inequalities and are rigorous; depending only on the validity of Rayleigh scattering theory. The formalism is applied to the problem of estimating the concentration of particulates in black smoker hydrothermal plumes. These particulates consist of several different metallic sulfides having different size distributions. It is found that the spherical-scatterer assumption results in over-estimating the total mass concentration by at most a factor of 5 and under-estimating it by at most a factor of 0.7.
Dominant pole scattering model for Arctic ice keels
Authors: Fricke J. Robert
Published: October 2005

Numerical simulations [J. Acoust. Soc. Am. 93, 1784(A) (1993)] and experimental measurements [J. Acoust. Soc. Am. 92, 2341(A) (1992)] show that scatter from ice keels for 0.5<ka<2.5 is dominantly dipolar for young keels and quadrupolar for old keels. This dichotomy arises from the fact that young keels are aggregations of loose ice blocks, and thus behave like fluids at low frequency, while old keels are frozen solid and behave like solids. To study this finding analytically, the method of images is used to develop a solution for a physical problem that is ‘‘near-by’’ the ice keel problem. Two plane waves of opposite polarity are incident on an elastic cylinder at angles ±γ with respect to a diameter of the cross section. Over the range 0.5<ka<2.5 and 0.2<ν<0.5, where ν is the Poisson’s ratio, the scattered field is dominantly dipolar for high Poisson’s ratio (corresponding to a fluid keel) and is quadrupolar for low Poisson’s ratio (a solid keel). These studies show that because ice density is nearly that of the surrounding fluid, radiation loading of the shear modes is extra sensitive to Poisson’s ratio. It is this sensitivity that causes the dominant pole to shift between a quadrupole and a dipole. Dense materials, say steel, do not have this property. [Work supported by ONR and Doherty Foundation.]
The low-frequency scattering action of fish schools
Authors: Garrelick Joel , Junger Miguel C. , Lamberton Mary L.
Published: October 2005

Enhanced low-frequency scattering levels from a single fish at its swimbladder resonance and a frequency invariant return for an octave or so above have been predicted by simple monopole scattering models [Love (1977)]. These characteristics have also been measured, more or less, with fish schools [McCartney (1967)]. In this talk the ‘‘more or less’’ is explored by modeling the school as a number of monopole scatterers quasi-randomly distributed within an ellipsoidal volume, with and without mutual scattering taken into account. The swimbladder natural frequencies themselves are also taken to be random with a uniform PDF over a finite band. For a given realization, overall returns are computed in both the frequency and time domains. Computed fluctuations in aspect are compared with those for a Gaussian amplitude distribution. The influence of mutual scattering is shown as a function of the mean free path among individual fish. Finally, it is noted that though swimbladder gas volume and bulk modulus indicate a P5/6 hydrostatic pressure dependence, swimbladder natural frequencies typically vary as P1/2 [Weston (1967)]. [Work sponsored by Naval Undersea Warfare Center, New London Detachment.]
Theoretical study of echo energy scattered by a random distribution of air-filled fluid spherical shells: Application to fish stock assessment by the echo integration method
Authors: Sun Zhigang , Gimenez Gérard
Published: October 2005

This work is intended to give a preliminary examination of the influence that the swimbladder may have on the linearity principle of the echo integration method. In doing this, the fish school is modeled as a random distribution of air-filled fluid spherical shells immersed in water. The wall of the shell represents the fish body whereas the inside of the shell represents the swimbladder. The mean echo energy scattered by such a distribution has been calculated as a function of the ratio b/a of inner to outer radius of the shell, with the interference of direct echoes, the shadowing effect, and the second-order scattering being taken into account. The numerical simulations show that at a given fractional volume number of targets, the mean echo energy scattered by the distribution is a bit larger than that predicted by the linearity assumption when b/a is less than a certain value κ, and it may be much smaller than the predicted value when b/a is greater than κ. Consequently, the swimbladder may be the major cause of the energy attenuation, due to the shadowing effect, and its influence on the linearity principle depends on its relative size.
In-situ target strength measurements of Antarctic zooplankton
Authors: Demer David A. , Hewitt Roger P.
Published: October 2005

In situ measurements of target strength were made of krill (Euphausiasuperba) and salps (Salpathompsoni) at 120 and 200 kHz. Concurrently, a 2-m Isaacs-Kidd underwater trawl was used to sample the zooplankton population; animal length, wet weight, and maturity stages were recorded. These data were combined to derive empirical models of TS versus length for both species. The individual target strength measurements were collected at 120 kHz with a split-beam echosounder and a single-target detection algorithm. Because the two transducers were essentially colocated, range bin and off-axis angles from the 120-kHz detections were used to extract the corresponding target strength from the 200-kHz single-beam data. Backscattering strengths of salps are shown to be higher at 200 than 120 kHz. Utilizing these scattering characteristics, signal separation methods are explored that would be useful in acoustic surveys of krill distribution and abundance. Data were collected as part of the United States Antarctic Marine Living Resources Program, near Elephant Island, Antarctica, during the Austral summer of 1994. [Work of D. A. Demer was supported by the Hertz Foundation.]
Identification of Hindi dental and retroflex consonants by native English and Japanese speakers
Authors: Pruitt John S.
Published: October 2005

Previous research has shown that English speakers have great difficulty distinguishing dental and retroflex stop consonants of the Hindi language (which occur in five pairs of stop consonants in Hindi). While both dental and retroflex consonants, in almost all of the manner/voicing contexts of Hindi, occur as allophones in English, they do not occur phonemically. Unlike English, Japanese includes an alveolar-retroflex distinction (the Japanese /d/ versus the flapped /r/). However, no research has determined whether Japanese speakers can distinguish the Hindi contrast. This research compared English and Japanese speakers’ ability to distinguish these Hindi stop consonants in four of the five manner/voicing contexts (breathy-voiced, prevoiced, voiceless-aspirated, and voiceless-unaspirated). Subjects were presented consonant-vowel syllables in three vowel contexts (/a/, /e/, /o/) that were produced by two native Hindi speakers. Marked differences were found between these two language groups that were dependent upon the manner/voicing context of the consonants. This research contributes to our understanding of the role of native language experience (phonemic versus phonetic) in the perception of non-native speech contrasts. [Work supported by NIDCD.]
Vowel devoicing in Japanese dialogue between teachers and hearing-impaired or normal-hearing children: Listener adaptive characteristics of dialogue speech production
Authors: Imaizumi Satoshi , Hamaguchi Sachiko , Deguchi Toshisada
Published: October 2005

Listener adaptive characteristics of Japanese vowel devoicing in dialogue were investigated by analyzing dialogue between teachers and hearing-impaired (HI) or normal-hearing (NH) children. Dialogue was recorded during a game through which seven teachers assessed the speech perception of seven hearing-impaired and seven normal-hearing children. The following results were obtained. (1) Devoicing rate was significantly lower in dialogue directed to HI than to NH. (2) For vowel /i/ in the second mora of /CVkita/, where C was one of /h,s,sh,ts/ and V /i,u/, unvoiced segments of not-fully-devoiced syllables that were mainly directed to HI tended to be shorter than those of fully devoiced syllables that were mainly directed to NH. This may indicate that the teachers avoided devoicing by shortening unvoiced duration and lengthening voiced duration for HI. (3) Monosyllables and pauses in dialogue directed to HI were longer than those directed to NH. These results suggest that the teachers controlled their speaking style to help the hearing-impaired to understand dialogue by avoiding or reducing vowel devoicing.
The acoustic vowel space of normal and misarticulating children
Authors: Tjaden Kristin , Tsao Ying-Chiao , Weismer Gary
Published: October 2005

Perceptual and acoustic descriptions of children’s articulatory errors typically have focused upon consonant productions, as compared to vowel productions. In the present investigation, three subject groups (15 misarticulating children age 4 to 6 who were referred for clinical services, 15 normally articulating 4- to 6-year-old children, and 15 young adult subjects) produced multiple repetitions of single syllable target words embedded in a carrier phrase. Midpoint (target) formant frequencies of selected vowels were measured and the resulting vowel quadrilaterals were then compared across subject groups to determine if children with so-called phonological delays characterized primarily by consonant misarticulations produced vowel spaces similar or different from normally articulating children. This is an interesting question because the focus on consonants in misarticulating children implies that speech production is guided by segmental strategies, when in fact many children in the 4- to 6-year-old range may be aware of the segmental structure of speech. Perhaps, then, misarticulating children produce vowel spaces that reflect a more global speech delay.
Newborn human cries: Prenatal cocaine exposed and nonexposed
Authors: Bauer Harold R. , Zimmerman Leigh
Published: October 2005

High fundamental frequency [F0] newborn vocalizations were studied in respect to F0 and duration. Late prenatal care mothers (initial visit/examination in 3rd trimester of pregnancy) birthing in a metropolitan, public hospital were considered as potential subjects. Enrolled newborn’s stool (i.e., meconium) and heel stick, pain induced cries were collected from the subjects in the newborn nursery, after mothers agreed to participate and receive post-discharge pediatric care. Meconiumtoxicology testing was used to exclude heroin, cocaine, marijuana, amphetamines, and meta-amphetamines maternal use by control subjects in the months prior to birthing, and to define prenatal cocaine exposure. Spectrographic analysis was carried out on the first ten cries. Cry duration, max. F0, min. F0, F0 range, initial F0, mid-F0, and ending F0 were studied. Descriptive and inferential statistical comparisons of the prenatal cocaine exposed and nonexposed infant vocalizations revealed differences with a previous report. Selected examples of the newborn vocalizations are presented for critical discussion. The findings will be discussed with respect to the acoustic structure and pattern of newborn pain cries, the analysis of harmonic–formant interactions and published interpretations of cocaine exposed newborn vocalizations. [Work supported by NIDA.]
Alaryngeal speech enhancement based on spectral substitution
Authors: Bi Ning , Qi Yingyong
Published: October 2005

A speech enhancement system based on spectral substitution was developed for alaryngeal talkers. In this system, the spectra of alaryngeal speech were converted to those of normal speech on a frame-by-frame basis. Synthetic speech was generated with the converted spectral information. The codebook for the spectral conversion consisted of cepstral coefficients of speech utterances. The rules for the spectral conversion were developed using procedures of supervised and unsupervised codebook adaptations. The synthetic speech produced by this spectral substitution scheme was compared perceptually to the synthetic speech produced by a linear predictive analysis-synthesis system, where only the voice source was replaced. The synthetic speech was also compared to the original alaryngeal speech in terms of intelligibility, acceptability, and intonation. [Work supported by NIH.]
Tongue prostheses for articulation
Authors: Fujimura Osamu , Gerdeman Bernice , DiGiacomo Dominic , Merrell Edwin
Published: October 2005

A 48-year-old male with normal speech underwent 6 years ago a total glossectomy with myocutaneous flap reconstruction. The voice control is natural in this patient. Prosthodontic devices have been made to test feasibility of improving speech intelligibility. All American English vowels (except retroflexed vowels) are articulated with virtually perfect identifiability with the use of a solid tongue prosthesis fixed on the lower teeth. Spring-loaded rotatable prostheses were deviced for consonantal articulations. The prosthesis is moved under the contraction of the muscle in the reconstructed flap in the posterior oral cavity, raising the ‘‘back of the tongue’’ or the ‘‘tip of the tongue’’ in combination with mandibular and labial control. X-ray microbeam recordings were obtained to observe the extent of controlled movements. The result is almost perfect intelligibility of most of speech sounds including apical and dorsal obstruents. The patient, as one of the coauthors of this paper, will demonstrate the use of the prosthesis as part of the presentation. [This work has been supported in part by Shannon Award (NIDCD ♯1 R55 DC00015-01A1) and by a research fund from ATR, International, both given to O. Fujimura.]
Band-envelope speechreading supplements derived from noisy speech
Authors: Lemay Danielle G. , Braida Louis D.
Published: October 2005

Listeners with severe-to-profound hearing losses often rely on speechreading for communication. Previous studies [Grant etal., Q. J. Exp. Psychol. 43A, 621–645 (1991); J. Acoust. Soc. Am. 95, 1065–1073 (1994)] have shown that amplitude envelope signals derived from bands of speech can substantially enhance speechreading. This study evaluated the effects of additive noise on this benefit. The supplement consisted of three tones (500, 1600, and 3300 Hz) amplitude modulated by the envelopes of the outputs of two-thirds-octave filters centered at 500, 1600, and 3300 Hz, respectively. This three-envelope signal improved word scores on CUNY sentence materials [Boothroyd etal., CUNY Rpt. RCI-10 (1985)] for 32% with speechreading alone to 94% when the supplement was derived from speech at +12 dB S/N. Roughly half of the benefit is retained at S/N=0 dB (60% correct). This result suggests that the band envelope signals can be successfully adapted for presentation to listeners with severely restricted dynamic ranges, since at an S/N of 0 dB, excursions of the component envelope signals are limited to roughly 12–15 dB by the relatively constant background noise. [Work supported by NIH.]