bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal response of an elastic sphere kidney stone and gallstone model to pulsatile plane wave excitation
Authors: Waag Robert C. , Case Timothy J.
Published: October 2005

An elastic sphere has been employed to model kidney stones and gallstones. Temporal harmonic amplitudes of the stress tensor components in the sphere were expressed in a spherical coordinate system using acoustic displacements found from an orthogonal function series with coefficients determined by boundary conditions. Corresponding temporal responses were then obtained via Fourier transformation and principal stresses as well as stress combinations proposed by von Misses and Tresca for the onset of inelastic behavior were calculated. Cross-sectional and three-dimensional displays of these stresses in the sphere at sequential instants of time shows the temporal growth and reverberant decay of the stress field resulting from an incident pulsatile plane wave. The model may be employed to study the influence of the incident waveform shape on the distribution of induced stress in kidney stones and gallstones.
Effects of different samples of reproducible noise on detection of a 20-Hz-wide interaural phase shift centered on 500 Hz
Authors: Grange A. N. , Yost William A.
Published: October 2005

Subjects’ thresholds were first determined for detection of an interaural phase shift of a 20-Hz band of equal-amplitude wideband noise. The narrow-band target was centered on 500 Hz, and generated a dichotic, Huggins-type pitch. A diotic band of either 100, 125, 150, or 900 Hz symmetrically surrounded the target band. Interaural phases for frequency components outside of the diotic band were drawn randomly from a rectangular distribution. After thresholds were determined via a tracking procedure, 20 independent samples were generated for each condition at each subject’s threshold. A two-interval forced choice task was used in which each interval was comprised of a 250-ms forward fringe followed by a 250-ms observation period. Sixty trials were presented in a block with each sample presented three times. Order of presentation was randomized across runs and each sample was presented a total of 96 times. P(C) ranged from chance (50%) to over 90% across samples having identical interaural parameters. In conditions where subjects’ thresholds were similar, allowing the same set of samples to be used for two or more subjects, there was a strong inter-subject correspondence with respect to P(C). Possible sources of these sample-specific effects will be discussed. [Work supported by NIH.]
Detection of a target signal in localized versus nonlocalized noise
Authors: Abouchacra Kim , Letowski Tomasz , Kalb Joel
Published: October 2005

Detection thresholds were measured for a spectrally complex target signal presented in either localized or nonlocalized speech-spectrum noise (65 dBA). Thresholds were obtained for 50 normal hearing subjects, in 40 different combinations of azimuth of the target and noise sources. In general, the results showed that the detectability of the target signal in localized noise was better than in nonlocalized noise. In the conditions where the target signal was presented in localized noise, the findings revealed that (a) poorest thresholds occurred when the target and noise were coincident; (b) thresholds improve as the amount of spatial separation between the target and noise source increases; and (c) best performance occurred when either the target or noise source was off of the median plane and at least a 45° azimuth separation existed between the sources. Improvements in detection thresholds amounted to as much as 15–18 dB, depending on the condition.
Evaluation of a linear interpolation scheme for approximating HRTFs
Authors: Kulkarni Abhijit , Colburn H. Steven
Published: October 2005

As part of a study of virtual acoustical environments, the ability of subjects to distinguish interpolated HRTFs from empirical HRTFs in the horizontal plane was investigated. Each interpolated HRTF was obtained by averaging empirical HRTFs from two positions chosen symmetrically about the location of interest. Empirical HRTFs were measured from the KEMAR mannequin in anechoic space. Subjects were tested using a 4I, 2AFC paradigm for several angles of interpolation using lowpass noise stimuli. Theoretical analysis predicted a useful lateralization cue for large interpolation angles. For a 2.2-kHz lowpass stimulus, subjects reported the use of such a cue and performed at 96% correct (averaged across four subjects) for a 30-deg angle. For a 10-deg angle, subjects reported no lateralization cue and performed near chance (53% correct), until they discovered a spectral cue increasing performance significantly (69% correct). Monaural performance was comparable to binaural performance, consistent with predictions for the use of spectral information. Results for combinations of interpolation angles and stimulus bandwidth will be presented, and implications for both basic and applied contexts will be discussed. [Work supported by NIDCD.]
Monaural echo suppression: Detectability of a delayed signal based on vowel formant structure
Authors: Chen Xiaofen , Cohen Marion F.
Published: October 2005

In order for echo suppression to occur, the ear must be convinced that the echo makes a reasonable acoustic match with the direct sound. It is plausible that the potential acoustic cues used to perform this task are similar to those used for auditory grouping, and include spectral location of vowel formants. An experiment was performed to investigate the role of vowel formant structure in monaural echo suppression. In a 2IFC adaptive procedure, the detectability of a masked signal, consisting of the second formants of two synthetic vowels, presented successively, was measured. The masker consisted of the first, third, and fourth formants of the same two vowels, repeated, so that it had four alternating segments. The signal either preceded the second segment of the masker, or was delayed relative to that segment. When the vowel order of the signal matched that of the second and third segments of the masker, the delayed signal was less detectable than when the vowel order was reversed in the signal. Likewise, when the vowel order of the signal matched that of the masker, the delayed signal was less detectable than the leading signal. These data suggest that the auditory system is able to group vowel formants based on expected spectral location and use that for echo suppression. [Work supported by AFOSR.]
Modeling the sensor/actuator response of a finite disk transducer flush mounted on a plate subject to fluid loading
Authors: Varadan Vasundara V. , Kim Jaehwan , Varadan Vijay K.
Published: October 2005

It is important to model the sensor and actuator function of a finite disk-shaped piezoelectric transducer in the environment that it will function in. This will involve taking into account the structure on which it is mounted, modeled here as a flat, solid, elastic plate and fluid loading to which the structure may be subject to. In addition, material damping in the plate and the transducer must be taken into account. The sensor response involves computation of the voltage induced in the transducer by an incident acoustic wave in the fluid or a force to which the plate may be subjected to. The actuator response involved computation of the acoustic field radiated into the fluid when the transducer is subject to a known voltage. A hybrid numerical method involving finite element modeling in the plate and transducer region and a plane wave representation in the fluid region will be used. [Work supported by ONR.]
Evaluation of objective vowel classifiers
Authors: Miller James D. , Kramer F. E. , Meyer D. J. , Lee S. , Uchanski R. M.
Published: October 2005

Four classifiers were examined for their ability to identify nine monophthongal American English vowels. The classifiers, (1) Bayesian, (2) a standard back-propagation neural net with one hidden-layer, (3) a modified ellipse method, and (4) an automatic region-drawing method, operated on two-dimensional vowel representations. Additionally, three different types of two-dimensional data were evaluated; (a) (log F1, log F2), (b) (norm log F1, norm log F2) normalized by a sensory reference [Miller, J. Acoust. Soc. Am. 85, 2114–2134 (1989)], and (c) (x’,y’) of the auditory-perceptual space [Miller, J. Acoust. Soc. Am. 85, 2114–2134 (1989)]. Our corpus of 2304 vowels spoken in a CVC context by male and female talkers includes stress and speaking-rate variations [Fourakis, J. Acoust. Soc. Am. 90, 1816–1827 (1991)]. For each vowel utternace and each data type, a single two-dimensional data point is computed from the vocalic segment selected by Fourakis. Separate training (75% of the data) and testing (25%) subsets of the corpus were used in a jacknife procedure. In general, all the classifiers except the ellipse method performed similarly, and obtained the highest scores using (x’,y’) data. However, unless training and testing of the classifiers is restricted to vowels that are relatively steady-state, identification scores are less than ideal (<90%). [Work supported by NIDCD.]
Design and commissioning of a new floor sound transmission facility
Authors: Halliwell R. E. , Quirt J. D. , Warnock A. C. C.
Published: October 2005

The pair of reverberation room that have been used at National Research Council Canada for about 30 years, are deemed too small by current ASTM standards. A new pair of rooms that incorporate some interesting ideas to satisfy the requirements and recommendations in both ISO and ASTM standards has just been constructed. One vertical cross section through each room is a five-sided polyhedron. The test specimen is at one of the sides. This design allows the room volumes to be large (about 175 cm3 each), the specimen to be a normal size, and yet to be one complete surface of the room. The niche between the two room is minimal. Both rooms are resiliently supported as is the floor support. The upper room is of a lightweight construction and the lower is of poured concrete. Floors are constructed on wheeled, heavy concrete frames that can be moved in or out of the slot between the rooms. A crane outside the room allows other test frames with floors already constructed to be inserted into the specimen opening. Some details of the design will be presented as well as sound transmission results from reference specimens from all three pairs of rooms at NRC. These differ quite markedly in size and results for receiving rooms ranging from 65–250 cm3 can be compared. A small amount of a detailed examination of the sound fields in the rooms based on measured and calculated data will be presented.
Inter-laboratory comparisons of low-frequency sound transmission: I. Conventional and intensity measurements
Authors: Vorländer M. , Warnock A. C. C.
Published: October 2005

Sound transmission through nominally identical steel plates was measured in two laboratories; NRC, Canada and PTB, Braunschweig in Germany. The two laboratories differ markedly in construction; one has rooms with volumes 65 and 250 m3 and the other volumes of 54 and 69 m3. The specimens measured 1.5×1.25 m and were mounted in window test frames that satisfied the recommendations of ISO 140. The measurement frequency range was extended to 50 Hz in each laboratory. As well as conventional 1/3-octave band measurements, sound reduction index was measured using sound intensity techniques. Measurements were made in both directions, that is, each room served in turn as the source room and then the receiving room. Similar behavior was seen in each laboratory; conventional measurements into the smaller room tended to give higher values of sound reduction index. When the mean values of sound reduction index for each laboratory for both directions of measurement are compared, agreement is good but there are still differences at low frequencies that need explanation. This paper presents the measured data. Possible reasons for the differences are discussed in the companion paper.
Noise isolation measurements of partitions and windows under highly absorptive and flanking conditions in the field
Authors: Campanella Angelo J.
Published: October 2005

Installed partitions, windows, and doors are often not situated ideally for sound isolation performance testing in terms of ASTM E 90 laboratory sound transmission loss (TL) and STC values. Test room quality specified in the ASTM E 336 and E 966 field methods may preclude TL measurement due to high absorption, small size, or flanking. Methods of Buckingham [NBS SP 20, 193–219 (S-506)], London [NBS RP 26, 419–453 (RP 1338) (1941)], and Donato [J. Acoust. Soc. Am. 40, 1–3 (1966)] were examined for field tests. Buckingham proposed the room space average sound-level method now used in ASTM E 90, ASTM E 336, and E 966. Donato proposed that a term of value 1/8 be added within the 10 log (S/A) absorption normalization term to account for direct sound. London proposed sound-pressure level measurements (SPL) flush to the specimen receiving room surface for field tests. Flush SPL can be normalized with receiver room space average SPL or absorption via RT60 to determine TL. Tests were recently performed on four windows installed in field conditions ranging from high absorption with no flanking to very large reverberant spaces with flanking. The flush SPL method combined with RT60 normalization provided the most credible results for comparison with laboratory STC, and also offered immunity to flanking. Data and comparative results will be presented.
Flanking transmission in wood-frame constructions caused by simple construction faults
Authors: Nightingale T. R. T.
Published: October 2005

Flanking transmission can seriously degrade the performance of building elements in the field. In cases of very poor construction, the actual field transmission loss may bear very little resemblance to the laboratory data. A facility has been constructed to examine the effects of flanking transmission in wood-framed construction. Measured sound insulation data are presented for partitions with potentially common construction faults. The faults considered are rank ordered as to their severity. Standard airborne and impact tests, surface velocity and intensity measurements are also assessed for their effectiveness as measurement tools.
Role of the absorption distribution and generalization of Sabine’s reverberation law in chaotic rooms: Geometrical and wave theory
Authors: Mortessagne Fabrice , Legrand O. , Sornette Didier
Published: October 2005

The theoretical validity of Sabine’s law of reverberation in the true geometrical acoustic limit (TGAL) with mirror reflection relies solely on the conditions that almost all rays are chaotic and that absorption is ‘‘sufficiently weak,’’ as demonstrated by Joyce [J. Acoust. Soc. Am. 58, 643 (1975)]. It is shown here that exponential decay law may still hold in the TGAL for realistic large absorptions, depending on the spatial distribution of the absorption within the chaotic room. This dependence stems from the role of special ray trajectories that are analyzed. It is also demonstrated theoretically and numerically that Sabine’s reverberation time is modified at large absorptions due to fluctuations in the number of encounters with the absorbing walls. This novel mechanism applies to many physical examples where a system decays from an initial metastable state with a generic exponential decay law, be it thermally activated or by quantum tunneling. A partial account of this work appeared in Europhys. Lett. 20, 287–293 (1992). Finally, a wave theory is given of Sabine’s law for room acoustics relying on ergodic properties of the eigenmodes. Besides the global problem of reverberation, wave acoustics in ergodic rooms offer a true richness of phenomena that can be tackled with the help of tools developed in ‘‘Quantrum Chaos.’’ A preliminary account of this work appeared in Lect. Notes Phys. 392, 267 (1991).
Performance of a large new anechoic chamber at the Canadian Bureau of Radiation and Medical Devices
Authors: Bly S. H. P. , Lightstone A. D. , Hewlings T. G. , Lourador J-L.
Published: October 2005

The large new anechoic chamber is to be used for health effects research and standards development for noise, and for other acoustics research not feasible elsewhere in Canada. The chamber’s free-field performance was quantified using measured deviations from the 1/R law for the variation of sound pressure with distance, R, from a point source in a free field. In measurements at 46 locations throughout the chamber, deviations were typically less than 1 dB for frequencies ranging from the design cutoff of 50 Hz to 20 kHz. The largest deviation was 1.9 dB. Impulse response analysis was also used to examine sound reflections. Background noise was found to be less than the design criteria used, which ranged from 22 dB at 50 Hz to 4 dB at and above 1600 Hz. Comparisons will be made to the few other chambers in the world which are of a similar size.
Recent data on audience and chair absorption
Authors: Beranek Leo L.
Published: October 2005

In 1960 (J. Acoust. Soc. Am. 32, 661–670) and 1969 (J. Acoust. Soc. Am. 45, 13–19), the author published a statistical study of audience and seat absorption based on data taken in a large number of concert halls and opera houses. This paper presents some more recent sound absorption data taken in reverberation chambers and in concert halls which shed light on the influence of seat construction on audience absorption.
Hearing melodies in continuous frequency modulations
Authors: Demany Laurent , McAnally Kenneth I.
Published: October 2005

A 1-kHz carrier was frequency modulated by the exponential of periodic time functions corresponding to the sum of a few sinusoids (e.g., sin ωt+sin 3ωt). The modulations were symmetric on the dimensions of time and log frequency [y(t)=y(k−t)=−y(k’−t)]. Each had three local maxima and three local minima per cycle. The peak-to-peak frequency excursion was typically 0.5 oct. At low rates of modulation, the stimuli were heard as complex glissandi. However, for modulation rates around 1.5 Hz, the dominant percept was a melodic motif comprising the pitches of the local maxima. Generally, the local minima were not heard as auditory ‘‘events’’ (pitch singularities). A similar perceptual asymmetry was not observed for sequences of discrete tones corresponding to the local maxima and minima of the continuous modulations. Additional experiments were performed to determine the frequency difference limens for maxima and minima of continuous frequency modulations. The carriers were modulated by the exponential of one cycle of a cosine function, starting at phase π or phase 0. For maxima and minima around 1 kHz, frequency shifts of maxima were markedly better detected than frequency shifts of minima. These results are in contrast to those predicted by consideration of the upward spread of masking.
Auditory image formation using a CMR paradigm: The role of AM, FM, and harmonicity
Authors: Grose J. H.
Published: October 2005

When a pair of comodulated narrow bands of noise is inserted into a larger set of independently comodulated noisebands, the amount of comodulation masking release (CMR) measured for the larger set is reduced. This interference effect can be mitigated to some extent by presenting further bands of noise to the contralateral ear which are comodulated with the intervening pair of bands. One interpretation of this release from interference is that the additional contralateral bands serve to draw the intervening pair of bands into a separate auditory image and that this more distinct segregation of the two sets of comodulated bands allows the auditory system to better perform a CMR on the original comodulated set. The purpose of this study was to apply the paradigm to situations where the commonality between the intervening pair of noisebands and the contralateral bands was some combination of three variables: AM (correlated, uncorrelated), FM (present, absent), and spectral spacing (harmonic, inharmonic). Results indicated that the release from interference occurred most often when coherent AM featured in the commonality, although a slight effect of coherent FM was also observed. [Work supported by the NIDCD R01-DC01507.]
Effect of frequency transposition on discrimination of amplitude patterns
Authors: Takeuchi Annie H. , Braida Louis D.
Published: October 2005

Sheft and Yost [J. Acoust. Soc. Am. 91, 2333 (1992)] reported that frequency transposition impaired discrimination of amplitude modulation patterns. They suggested that our failure to supplement speechreading effectively with amplitude envelopes derived from a particular frequency band of speech and carried at a lower center frequency [Grant etal., Q. J. Exp. Psychol. 43A, 621–645 (1991)] might reflect a general auditory limitation on the ability to compare amplitude modulations across carrier frequencies. This study examined the effect of systematic practice on performance in an AXY three-interval amplitude-modulation discrimination task in which all signals were narrow-band noises with bandwidths of 50 Hz and durations of 400 ms. The difference in center frequency between the A stimulus and the X and Y stimuli increased in intervals of 10% to more than an octave. With practice, the decline in discriminability was substantially lessened and some subjects showed almost no decline. This result suggests that even if perception of amplitude modulation is initially dependent on carrier frequency, listeners can learn to compare amplitude modulation patterns across large frequency differences. [Work supported by NIH.]
Dichotic beats of mistuned consonances
Authors: Feeney M. Patrick , Burns Edward M.
Published: October 2005

Temporal envelope perception, aural harmonics, and combination tones have all been proposed as mechanisms to explain the beats of mistuned consonances (BMC). This study used dichotic presentation of mistuned octaves to explore a between-channel temporal explanation. A 2I-2AFC procedure was employed to determine subjects’ ability to detect BMC. Masking in dichotically complementary frequency regions was used to eliminate effects caused by aural harmonics and acoustic crossover. Subjects were able to detect dichotic BMC under these conditions. Performance deteriorated with an increase in fundamental frequency as expected from previous studies on monotic BMC and on binaural beats. Envelopes of pairs of beating sinusoids were used to further explore the temporal basis of BMC. Subjects were able to detect mistuned consonant envelopes for both monaural and dichotic presentation. A third experiment examined the detection of the ‘‘sweep-tone’’ pitch effect using the same stimuli. The results of these experiments will be discussed in terms of within- and between-channel phase perception. [Research supported by the Virginia Merrill–Bloedel Hearing Research Center, University of Washington.]
The contribution of onset, offset, and comodulation to the grouping of noise bands
Authors: Kaernbach Christian
Published: October 2005

Auditory grouping uses two difference kinds of cues; ‘‘vertical’’ curs act on small temporal sections and are based on similarity principles (frequency, harmonicity, onset/offset, modulation), whereas ‘‘horizontal’’ (sequential) cues depend on the history of the stimulus. The present study addresses the relative importance of several vertical grouping cues. Twenty naive subjects were presented with auditory scenes of one to five elements. The elements were noise bands with a width of 50 Hz and a duration of 0.12 to 0.36 s. The center frequencies, the onsets and the offsets were randomized; in half of the scenes the noise bands were comodulated. The subjects were asked how many events they had heard. The number of perceived auditory events was on the average smaller than the number of presented noise bands. This could be shown to depend mostly on onset synchrony, to a slightly smaller degree on offset synchrony, and only very little on comodulation.
Final group presentation
Authors: Brooks Bennett M. , DuBois James , Eldred Kenneth M. , Hoover Robert M. , Krishnappa Govindappa , Sutherlad Louis C.
Published: October 2005

This final plenary session of the Workshop will include presentation by the moderators/recorders of all the working groups on their findings. The final set of recommendations will be presented to the meeting of the Technical Committee on Noise, to be held on Thursday evening, 20 May 1993
Acoustic daylight: Design and performance of a multi-beam imaging system
Authors: Potter John R. , Buckingham Michael J.
Published: October 2005

A multibeam ‘‘Acoustic Daylight’’ [Buckingham etal., Nature 356 (1992)] system is being developed that is capable of forming real-time images at 30-Hz frame rate with 127 simultaneous beams. Objects at 10- to 200-m range will be imaged, primarily employing acoustic information over 8–70 kHz. The raw data rate of such a system is over 25 Mbyte/s, which poses serious beamforming, real-time imaging, and data storage problems. The solutions we have developed include: an acoustic lens in the form of a spherical reflector with multi-element sensor (which achieves beamforming geometrically rather than through phasing); frequency-estimator preprocessing; and an economic 40 MFlop DSP engine. The color and intensity of each pixel of the final image will be determined by the spectral shading and intensity of the received signal in each beam. The limitations of the design are explored in terms of their impact on expected performance. Image simulations have been computed based on a numerical sum of a closed-analytic expression for acoustic energy scattering from a submerged body. The illuminating noise field is chosen to represent a shallow-water waveguide. Several objects are chosen for image synthesis, corresponding to obvious applications of interest. [Work supported by the Office of Naval Research.]
Imaging of ocean subbottom structure using swath mapping data: Feasibility studies
Authors: Sen Mrinal K. , Akbar Faruq A. , Stoffa Paul L. , Gettrust Joseph A.
Published: October 2005

With the aim of resolving small scale geologic features within upper 100 m of sediments, NRL-SSC has developed a high-resolution swath mapping device based on SeaMARC sidescan sonar technology but with additional parametric 500-Hz, 1-kHz, and 2-kHz source capability. Methods have been developed for modeling and imaging of such data in order to address the problem of image resolution. A modeling method that uses an elastic Kirchhoff–Helmholtz (KH) formulation rapidly calculates the arrival time, and amplitude of scattered signal. KH synthetics have been compared with elastic finite difference results. Synthetic phase data are computed by ray tracing for a given subsurface model. Also, a Kirchhoff migration code has been developed that uses both the travel time and angle for imaging conditions. The imaging method has been tested on synthetic data with various degree of random noise added so as to investigate how the signal-to-noise ratio affects the images. These methods will be applied to real data collected by NRL. Like any imaging method, we require an estimate of subsurface velocity. This is being done by using several different possible velocity models and comparing the imaging results. [Work supported by ONR.]
A comparison of frequency spectra of normal and hoarse voices
Authors: García Amando , Romero José , Cervera Francisco
Published: October 2005

In the framework of source research for developing an auxiliary tool for voice rehabilitation, the differences between normal and hoarse voices have been analyzed. Five women with normal voices (control group) and five hoarse women (experimental group) have been selected as study subjects. Frequency spectra from laboratory voice recordings of the five Spanish vowels for all subjects have been obtained with a real time analyzer. The frequencies of fundamental pitch (F0) and the first four formants (F1, F2, F3, and F4) are similar for both groups of voices. However, this demonstrates that there is a loss of harmonics in people with hoarse voices. The main intensities (spectrum envelopes) for experimental group subjects are always lower than that for control group subjects. The differences between the two groups are specially located for the frequency range of 1000–3000 Hz (about 20 dB).
Perception of coarticulatory cues in the speech of profoundly hearing-impaired and normally hearing children
Authors: Baum Shari R. , Waldstein Robin S.
Published: October 2005

Two experiments investigated the perception of coarticulatory cues in the speech of normally hearing (NH) and profoundly hearing-impaired (HI) children. To examine anticipatory coarticulation, five repetitions of the syllables [ši šu ti tu ki ku] produced by nine NH and nine HI children were edited to include only the aperiodic consonantal portion. To explore perseveratory coarticulation, comparable segments were excised from the syllables [iš uš it ut ik uk]. Ten listeners were asked to identify the missing vowel. Results revealed that, for anticipatory coarticulation, listeners were able to identify the absent vowel with better-than-chance accuracy for all stimuli but the HI speakers’ [š] tokens. For perseveratory coarticulation, identification accuracy was worse overall, but still significantly above chance for the NH stimuli; for the HI children’s productions, only [k] tokens yielded better-than-chance vowel identification. Listener’s identification of NH speakers’ tokens was significantly better than that of HI speakers’ productions for both anticipatory and perseveratory contexts. Results are discussed in relation to the nature of speech production in the HI and the role of contextual cues in speech perception.
Processing of stop-vowel syllables by normal and language-impaired children
Authors: Stark Rachel E. , Heinz John M.
Published: October 2005

It has been claimed that language-learning disordered children have impaired rapid-rate auditory processing. One manifestation is the failure to identify stop-vowel syllables; another less fine-grained discrimination of stop-vowel syllables. In the present study, 20 language-impaired (LI) and 20 normal (LN) children (6 to 10 years) attempted to identify /ba/–/da/ syllables within an adaptive paradigm. When they failed to do so, they were given a change/no change discrimination task with these stimuli. Formant transition duration (FTD) ranged from 80 to 40 ms. The syllable pairs had either five or two formants. As in previous studies, LI children failed the identification task, even for syllables of 80-ms FTD, significantly more often than LN. They were able to discriminate the syllables. Number of formants was not a significant variable. A subgroup of LI and LN children were subsequently asked to produce the test syllables. In both groups, children unable to produce the syllables had difficulty in identify them. The reverse was not true. Perception difficulties were not predictive of production errors. [Work supported by NIH.]
Reading disability: A deficit in rate of auditory processing or in phonetic coding?
Authors: Mody Maria , Studdert-Kennedy Michael
Published: October 2005

The study investigates a general hypothesis regarding the bases of certain reading disabilities: poor readers suffer from an impaired rate of auditory processing [P. Tallal, Brain Lang. 9, 182–198 (1980)], such that they are unable to discriminate or detect the order of a pair of brief complex tones at short interstimulus intervals. Such children also had difficulty with two synthetic speech sounds, /ba/ and /da/, on analogous tasks, which was similarly attributed to a deficit in the processing of rapid acoustic changes, such as those which occur in formant transitions signaling place of articulation in stop consonants. The present study, in establishing the significantly lower performance by poor readers, compared to good readers, with /ba/ and /da/, at short interstimulus intervals (100, 50, and 10 ms), however, failed to show any significant difference between the groups when the acoustic-phonetic contrast of the stimulus pair to be discriminated was increased, as with /ba/–/sa/ or /da/–/(sh)a/. Further, that the good and poor readers here, did not differ significantly on discrimination at these short interstimulus intervals, with acoustically similar nonspeech sinewave analogs of /ba/ and /da/, appears to implicate the role of phonetic processing.
Application of sidescan sonar to geological sea floor mapping
Authors: Twichell David C. , O’Brien Thomas F.
Published: October 2005

Digital sidescan-sonar images collected during a systematic mapping of the deep water part of the US continental margins, show a more complex near-surface geology than anticipated from previous mapping programs. For example, reconnaissance mapping with the GLORIA system (6.5-kHz operating frequency) in the Gulf of Mexico revealed channels extending hundreds of kilometers across the basin floor and discontinuous high-backscatter deposits in areas previously inferred to be laterally uniform deposits. Subsequent studies over part of the same area using the 27- to 30-kHz SeaMARC system permitted a detailed mapping of smaller channels and the high-backscatter deposits around their ends while cores permitted a link between seafloor geology and the imagery. Sandy and silty beds ranging from 10–118 cm thick occur in the areas of high backscatter and muds from areas of low backscatter. The imagery and cores in some cases permit mapping the extent and geometry of individual deposits. The deposits are a series of laterally discontinuous sand and silt lenses with abrupt edges rather than a continuous sheet of sand as previously was inferred for this area. This complex geology needs to be incorporated in efforts to understand the interaction of acoustic signals with the seabed.
Microbathymetry from Shape From Shading of sidescan acoustic imagery
Authors: Nishimura Clyde , de Moustier Christian
Published: October 2005

Shape From Shading (SFS) is a methodology for extracting the topography of a surface given the acoustic (or electromagnetic) backscattered imagery. As a sidescan image is of generally finer spatial resolution than multibeam bathymetry at the same frequency, there is some promise that SFS can provide information on the microtopography of an area. However, several key assumptions need to be made in order to apply SFS techniques on sidescan data; foremost of these assumptions is that of homogeneity of the backscattering properties of the seafloor across the imaged area. The sidescan sonar device can also introduce ambiguities in the SFS method if a flat-bottom assumption is used to position the pixels and/or the far-field transmit beam pattern is poorly known. The results obtained from SFS can be readily compared to acoustic data collected from new bathymetric sidescan systems that produce coregistered bathymetry and sidescan images (companion presentation by C. de Moustier, same session). [Work supported by ONR.]
Neural computing techniques for acoustic image processing
Authors: Dzwonczyk Mark
Published: October 2005

Computational architectures modeled after the biological nervous systems, so-called neural networks, have been shown to excel at pattern classification problems where the input data set is large and corrupted by noise and the solution formulation is not well defined. This paper discusses the application of neural computing techniques to a target detection problem with side-scan sonar data. A brief review of the fundamental concepts of feed-forward neural networks is first presented. Image segmentation and classification with a large analog electronic neural network are then described. It is shown that such neural computing approaches can be expected to be more robust than conventional statistical classifiers and are far better suited for deployed, real-time implementation of the system architecture.
Shape reconstruction from high-frequency sonar data for robotic tasks
Authors: Leonard John J. , Chryssostomidis Chryssostomos , Moran Bradley A.
Published: October 2005

This talk will describe an approach to the recovery of geometric object shape descriptions from high-frequency sonar data for robotic applications. The goal is to recover explicit geometric surface descriptions for man-made objects, by fusing the geometric constraints of multiple sonar returns obtained by a moving autonomous underwater vehicle (AUV). Automated sensor data interpretation is made difficult by the pervasive problem of dataassociation—uncertainty in the origins of measurements—in addition to the uncertainty in the values of measurements (noise) that is present in more traditional estimation and control problems. This problem is particularly severe when using sonar, for it is impossible to determine the geometry (e.g., sphere, cylinder, plane, corner, or spurious multiple reflection) that produced a single time-of-flight sonar return in isolation. One must first group measurements from different sensors and/or different sensing locations that have a common origin, to characterize the reflecting surface geometry. State estimation or surface fitting techniques can then be performed on correctly classified sets of measurements to complete the shape recovery process. Experimental results will be presented for two applications: (1) land robot map building and localization using the 50-kHz Polaroid ultrasonic ranging system, and (2) underwater scene reconstruction using a 1.25-MHz mechanically scanned profiling sonar.
Inverting, imaging, and mapping ocean-basin reverberation onto high-resolution bathymetry
Authors: Makris Nicholas C. , Berkson Jonathan M.
Published: October 2005

The objective of this paper is to determine the relationship between low-frequency ocean-basin reverberation and bathymetry. Long-range reverberation data acquired on the western flank of the Mid-Atlantic Ridge (MAR) are mapped onto high-resolution bathymetry. Since reverberation was measured via horizontally towed line array, there is a ‘‘right–left’’ ambiguity about the array’s axis and a decrease in resolution for off broadside beams and more distant returns. These ambiguities make an objective correlation between reverberation and bathymetry difficult. Therefore, an optimization procedure has been applied for eliminating the right–left ambiguity and maximizing resolution by simultaneously inverting data taken with differing array locations and orientations. Combined with range-dependent propagation modeling, the images show that distant reverberation is significant when the intermediate propagation path is free from bottom interaction. Since the experiment site is primarily bottom-limited, such paths are not abundant, and a sparse azimuthal distribution of strong returns at convergence zone intervals is often found. In general, strong returns coincide with prominent bathymetric features, such as abyssal hillsides. However, such correlations must be made judiciously because the azimuthal resolution of distant returns is often on the order of the width and separation between ridges in the MAR’s continuously rugged bathymetry.
Time-domain fluid–solid interaction and the proliferation of response frequencies
Authors: Jones-Oliveira Janet B. , Harten Leo P.
Published: October 2005

Exact modal solutions for the shell displacements and fluid pressure field resulting from the transient loading of a submerged, spherical shell are well-known [H. Huang, J. Acoust. Soc. Am. 45, 661–670 (1969)]. Comparisons of the shell deformation time histories with experimental data have been published previously [J. B. Jones-Oliveira and P. J. Wender, 55th Shock & Vib. Bull., Suppl. 3, 59–76 (1986)]. Herein, the analysis of the unloaded versus fluid-loaded frequencies reveals the effect of the fluid on the structual response to be more complex than simple damping and/or added mass. The fluid introduces a proliferation of frequencies in the structural response which is independent of the loading. The additional frequencies, which are introduced as a function of the expansion mode number via the fluid coupling, are associated with additional roots of an ever increasing higher-order system. The relative influence of the low, intermediate, and high frequencies are investigated. It is shown that while the proliferant frequencies are strongly damped and contribute little to the late time behavior in the far field, they can dominate the early time behavior. [This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.]
Vibrations of core walls with connecting beams
Authors: Sümer Ö. , Aşkar G. , Dökmeci M. C.
Published: October 2005

Vibrations of a singly symmetric core wall structure coupled with connecting beams is studied using Vlasov’s theory. Due to the presence of connecting beams, shear transfer occurs between the open edges of the core wall. The connecting beams are modeled as a continuum media with equivalent stiffness property. The results include warping effects and shearing deformations in the plane of the wall. Formulations for displacements and rotations at the top of the structure are given [cf. Ö. Sümer and G. Aşkar, Thin-Walled Struct. 14, 193–208 (1992)]. Results are compared with those of open core walls without connecting beams. [Work supported by TÜBITAK.]
An actuarial approach to cochlear implant candidacy in deaf children. I: Development of test instruments
Authors: Eran Orna , Boothroyd Arthur
Published: October 2005

Cochlear implants are being used extensively in the habilitation and rehabilitation of profoundly and totally deaf children. It is generally accepted that an implant can provide significant access to acoustic speech information to children who cannot obtain this information through more conventional devices. Appropriate decisions regarding implant candidacy can be difficult in this population, however, because many of the children who are potential implantees are too young to perform reliably on tests that measure speech perception capacity. The purpose of this presentation is to describe two tests of speech perception assessment that are used with young deaf children. THRIFT is a three-interval, forced-choice oddity procedure. The results depend on the adequacy of sensory data rather than on cognitive and linguistic status. IMSPAC is an imitative test for children as young as 3 years. In older subjects, scores obtained on IMSPAC correlate with those obtained on the THRIFT. The presentation will include data on applicability, reliability, validity, and efficiency of both tests. [Work supported by NIH Grant No. 2PO1DC00178.]
An actuarial approach to cochlear implant candidacy in deaf children. II: Comparison of implants and hearing aids
Authors: Boothroyd Arthur , Eran Orna
Published: October 2005

The perception of speech pattern contrasts, via hearing aids, was measured in approximately 100 hearing-impaired children with a wide range of hearing losses. A regression function for performance on hearing loss were generated. Using identical tests, data were collected from approximately 60 profoundly deaf children who had been fitted with cochlear implants. Using the regression function obtained from the hearing aid users, the implantees’ speech perception scores were converted to ‘‘equivalent hearing loss.’’ The cumulative distribution of equivalent hearing loss was used to estimate the probability that a child with a given hearing loss would be expected to perform better with a hearing aid than with an implant. The data suggest that the hearing loss should be in excess of 105 dB before the odds in favor of superior performance with an implant are acceptably high. A factor analysis of the implantees data suggests four relatively independent factors that were labeled: perception, age, experience, and age-at-onset. [Work supported by NIH Grant No. 2PO1DC00178.]
Single- versus multichannel vibrotactile supplements to intonation and stress by normal-hearing and hearing-impaired adults
Authors: Bernstein Lynne E. , Auer Edward T. , Coulter David C. , Tucker Paula E. , Demorest Marilyn E.
Published: October 2005

The possible benefit of a wearable, single-channel versus eight-channel tactile aid for conveying voice fundamental frequency (F0) was estimated in three experiments. Severely or profoundly hearing-impaired (HI) and normal-hearing (NH) adults identified position of stressed words and rising versus falling intonation in sentences previously recorded for this purpose by Bernstein etal. [J. Acoust. Soc. Am. 85, 397–405 (1989)]. In experiment 1, NH subjects performed the identification task in counter-balanced visual-alone (VA) and visual-tactile (VT) conditions. Both tactile configurations conveyed intonation but neither conveyed stress. In experiment 2, NH subjects performed the task tactile alone. Both stress and intonation were conveyed. In experiment 3, pre- and post-lingually HI subjects demonstrated effects of the aid for identification of intonation but not of stress. As in the previous study (Bernstein etal., 1989), visual stress was highly accurate in all VA conditions and tactile information shown to be present in experiment 2 did not improve identification in VT conditions.
Automated derivation of phonemic spectral distribution in speech output of nonlinear hearing aids
Authors: Erickson Faye , Yeung Eddy , Boothroyd Arthur
Published: October 2005

Interactions occur between the temporal characteristics of nonlinear processing schemes and the temporal and spectral properties of speech. Uncertainties in the nature and extent of these interactions make it difficult to predict hearing aid performance with speech input. An option is empirical measurement, but the collection of spectral data on a sample of phonemic segments can be prohibitively time consuming. This paper describes progress toward the development of an automated process. Input is derived from digitized samples of connected speech in which the temporal locations of segments of interest are already known. Recordings of speech output are, themselves, digitized. Using a known onset marker, the segments of interest are automatically extracted, subjected to FFT transformation, and integrated over a moving 1/3-oct window. The intensities and frequencies of key spectral points from each spectrum are displayed on a graph of intensity versus frequency for comparison with the input data. [Work supported by NIDRR Grant No. H133E80019.]
Estimated hearing handicap (using the AMA method and a self-evaluation questionnaire) versus reduction in speech intelligibility in quiet and noise
Authors: Nilsson Michael J. , Felker Donna , Senne Allen , Soli Sigfrid D.
Published: October 2005

Three methods of estimating hearing handicap were compared in subjects with bilateral sensorineural losses. Sentence speech-reception thresholds (sSRT) measured in quiet and 65 dB(A) noise were compared to the American Medical Association (AMA) method, based on pure-tone thresholds above 25 dB HL, and to a self-evaluation of handicap (Hearing Handicap Inventory for Adults, HHIA). The AMA correlated highest with sSRTs in quiet (r=0.92), followed by sSRTs in noise (r=0.81), and directional hearing in noise (r=0.84). The HHIA was confounded by age effects, and increasing age decreasing perceived handicap. Thresholds were also measured with noise at a sensation level (SL) 25 dB above sSRTs to partially compensate for audibility differences among subjects. In this noise condition, the AMA correlated with sSRTs in noise (r=0.76) and directional hearing in noise (r=0.58), though the directional hearing is better predicted by pure-tone thresholds at 3 kHz (r=0.64). Stepwise regression analysis suggests handicap continues below 0% AMA handicap in the quiet and 25-dB SL noise conditions.