bluuebunny/crossref_metadata_2025 huggingface dataset:
Can we really understand speech through the skin?
Authors: Osberger Mary Joe
Published: October 2005

The purpose of this presentation is to (1) present longitudinal data on the speech perception abilities of profoundly hearing-impaired adults and children who use wearable vibrotactile aids, and (2) raise issues relevant to developing improved tactile devices. Data collected to date reveal that most of the profoundly hearing-impaired subjects in this study perceived speech better when using a seven-channel vibrotactile aid than when they used a two-channel device. Even with the seven-channel instrument, the highest levels of performance were limited largely to discrimination and identification of speech features (segmental and suprasegmental) and enhanced speechreading. Whereas these are clinically significant findings, it is not clear if these results reflect perception of linguistically relevant units of speech or merely perception of acoustic events. Understanding words in sentences without visual clues would provide the most convincing evidence that speech can be understood through the skin. This level of performance has not been realized with current tactile aids. The ability of Tadoma users to understand conversational speech from feeling the articulatory movements of the talker suggests that speech understanding might be possible if devices delivered a richer speech signal to the user. This and other issues related to device development will be discussed.
Analytic study of the fundamental speech skills test
Authors: Levitt Harry , Eadie Frank , Youdelman Karen
Published: October 2005

The fundamental speech skills test (FSST) evaluates basic speech production skills and is designed for use with hearing-impaired students. A field study was performed in which 250 hearing-impaired students (age range 6 through 19 yr) were evaluated. A series of factor analyses was performed on the data, the results of which showed distinct patterns among basic speech skills. Relationships with hearing loss, age, and gender were examined. The primary factors were found to be vowel production, consonant articulation, breathstream management, pitch control, stress and intonation, and syllabification. Similar rates of improvement with increased residual hearing were observed for almost all factors. Age effects differed among the factors. Male-female differences were observed primarily with respect to pitch control.
Longitudinal changes in speech production in children with cochlear implants
Authors: Carney Arlene E. , Firszt Jill , Johnson Cynthia J. , Carney Edward
Published: October 2005

The purpose of this study is to determine when and how subphonemic changes in speech production lead to changes in speech intelligibility in three prelingually deafened children with poor speech production skills, following the receipt of multichannel cochlear implants. Measurements of open- and closed-set speech intelligibility were made pre-implant, and at 3, 6, 12, and 18 months post-implant. In addition, monosyllabic word tokens were analyzed perceptually with reduced aspect feature transcription (RAFT) [A. E. Carney, J. Acoust. Soc. Am. Suppl. 1 87, S89 (1990)] to determine global articulatory features. Results indicated that relatively large changes in syllable shape, vowel space, and consonant manner preceded small changes in speech intelligibility. RAFT results were displayed in matrix format for each test period. Matrices were compared to estimate which production changes showed consistent patterns over time. Results will be discussed in terms of base-line performance and expected rate of change for prelingually deafened children who received cochlear implants.
Effect of spectral envelope smearing on speech reception in noise and competing speech
Authors: ter Keurs Mariken , Festen Joust M. , Plomp Reinier
Published: October 2005

The effect of reduced spectral contrast on the speech-reception threshold (SRT) for sentences in noise, and on phoneme identification, was investigated with 16 normal-hearing subjects. The SRT increases—to about the same extent for a male as for a female voice—as spectral energy is smeared over bandwidths exceeding the ear's critical bandwidth. Phoneme identification shows that vowels are more susceptible to this type of processing than consonants. Vowels are primarily confused with the back vowels /ɔ,u/, and consonants are confused where place of articulation is concerned. In competing speech normal-hearing subjects show a 6–8 dB lower SRT for sentences than in steady-state noise, while sensorineurally hearing-impaired subjects do not [J. M. Festen and R. Plomp, J. Acoust. Soc. Am. 88, 1725–1736 (1990)]. As frequency resolution may contribute to this effect, and as fluctuating interferences of speech are very common in daily situations, the extent of the threshold difference between noise and speech masker was investigated for a number of smearing bandwidths.
Relating ocean acoustic ambient noise to the ocean surface dynamics
Authors: Kennedy Robert M.
Published: October 2005

The acoustical significance of ocean surface dynamics has been documented for years. Motivation for establishing the required causal relations between these two physical processes has existed for decades. The goal has eluded investigators because of the complexity of both the acoustic and oceanographic mechanisms involved. Significant contributions have been made by a progression of laboratory measurements of various spatial scales as recently reported [H. Medwin, J. Acoust. Soc. Am. Suppl. 1 88, S1 (1990); L. A. Crum et al., J. Acoust. Soc. Am. Suppl. 1 88, S2 (1990)]. The work discussed here continues the progression in spatial scales by utilizing a relatively deep water basin (The Tongue of the Ocean, the Bahamas) in a quasicontrolled environment which made a broadband measurement (40 to 4000 Hz) of the vertical directional spectrum of the ambient acoustic field. The 1-yr database of directional spectrum is dominated by local (fetch limited) water surface conditions over a wide range of environmental conditions. While the exploratory nature of the experiment limited the amount of supporting meterological and oceanographic measurements made, the results give direction to what are the likely independent variables of the experiment. A discussion of the key environmental variables and the consistency of the results with existing theories is given in the context of the design of a future experiment to relate the acoustic ambient with ocean surface dynamics.
Laboratory measurements of forward and backscattering from striated surfaces
Authors: Williams H. E. F. , Kille R. , Yang T. C.
Published: October 2005

A tank experiment was devised to measure forward and backscattering from single and multiple rods distributed on the water-air interface oriented normal to the plane of scattering. The cylindrical rods made of acrylic simulate the soft half-cylindrical protuberances used by Twersky in calculating scattering [J. Acoust. Soc. Am. 22, 539–546 (1950)]. (The Burke-Twersky model has been used frequently to model under-ice scattering in the Arctic Ocean.) To measure the scattering function (including the specular reflection and backscattering) from the cylindrical rods, a new experimental setup using an array of small diameter (0.05 in.) transducers was used to receive the scattering returns at different angles simultaneously. The source is a large diameter (3 in.) transducer operating at 100 kHz, with a narrow beam (<10 deg) to minimize “leakage” into backscattering angles. With the cylindrical rod radius of 1.6 mm, the scattering corresponds to ka = 0.67, which is the equivalent of low-frequency (∼20 Hz) scattering from the under-ice ridges. Preliminary results of scattering from cylindrical rods are in reasonably good agreement with the Twersky calculations. [Work supported by ONR.]
Site selection and characterization for the ARSRP scattering experiment
Authors: Caruthers Jerald W. , Bowles Fredrick A. , Kalra Ashok K.
Published: October 2005

A fine-scale acoustic bottom scattering experiment is planned for the summer of 1993 on the Mid-Atlantic Ridge flank north of the Kane Fracture Zone as part of the Acoustic Reverberation Special Research Program (ARSRP). The site (or sites) of the detailed experiment will be 5×5 km. To support selection of the site, a reconnaissance experiment is planned for the summer of 1991. To aid in that selection we have developed four specific sites for collation of detailed physical and geological data for use in simulations of expected scattering results in both the reconnaissance and fine-scale experiments. This preselection of sites will assist in targeting the reconnaissance and interpretation of the resulting acoustic data, although they are not expected to be the final sites selected. The sites were selected to be almost completely within existing high-resolution bathymetry swaths and covered by, or very near to, a seismic line. Acoustic travel times to the surface and return of not much less than 5 s (water depths > 3400 m) were also required. The selected sites represent the following four geomorphic regimes: (a) smooth, flat, deep sedimented valley floor; (b) high, level, rough thinly sedimented plateau; (c) long, steep slope or escarpment; and (d) small-scale fractures, faults, or fissures. The four sites are within the region bounded on the northeast by 26°30′ N, 46°10′ W and on the southwest by 26°00′ N, 47°20′ W. Presented here are the physical and geological descriptions of the sites. [Work is supported by ONR.]
Concert Hall Acoustics—1991
Authors: Beranek Leo L.
Published: October 2005

Acoustical design of concert halls began with Wallace C. Sabine who developed the reverberation equation and advised on Boston Symphony Hall (1900). Little additional information was learned in the next half-century. The use of reflecting panels in large spaces was introduced in halls with acoustically adverse shapes between 1953 and 1959. Next followed an understanding of sound absorption by audiences in different densities of seating, the initial-time-delay gap, and the value of lateral reflections. The London Royal Festival Hall and New York Philharmonic Hall confirmed the importance of those findings and revealed additional design requirements for reflective panels and sound diffusion. Extensive subjective studies, both in actual halls and in laboratories with electronically produced acoustical environments, were performed in Göttingen and Berlin (Germany), England, Denmark, Japan, and Canada. Those studies, when combined, revealed five orthogonal subjective attributes of concert hall quality: reverberance, loudness, envelopment, intimacy, and bass balance. These, in turn, are related to the objective quantities: initial and subsequent reverberation times (RT); cubic volume and audience area; lateral reflections and diffusion; initial-time-delay gap and subsequent reflections in the first 50 ms after arrival of the direct sound; and the slope of the initial RT versus frequency curve between 125 and 2000 Hz. An additional important subjective attribute is related to the physically measured ratio of the reflected energy in the sound field during the first 50 ms and that after 50 ms. Concert halls built since 1975, principally in Europe, United States, and Japan, constitute a “laboratory” for confirmation of those subjective attributes and related objective parameters.
The ultrasound-detecting ear of the praying mantis—Form and function
Authors: Yager David D.
Published: October 2005

Praying mantises have sensitive ultrasonic hearing mediated by a single ear located in the ventral midline of the body. The ear comprises two teardrop-shaped tympana facing each other in a deep, longitudinal groove; they are separated by less than 150 pm. Each tympanum is backed by a tightly adherent tracheal sac. Sensory transduction by 30–35 sensory neurons takes place at the extreme anterior end of each tympanum. Neurophysiological and behavioral tests confirm the prediction that the auditory system lacks directionality. The advantage of a single ear in the midline is not clear, but physiological evidence suggests that location in the deep groove increases sensitivity by 4–6 dB. The midline ear of the mantis is part of an “early warning system” affording protection from echolocating bats. Tethered flight and free flight experiments have shown that the mantis begins responding behaviorally within 50 ms with full foreleg extension and abdomen dorsiflexion; a change in flight path begins in 100–200 ms. It is hypothesized that the abdominal flexion throws the flying mantis into a stall out of which it rolls into a power dive. The maneuvers are very effective: In field trials with wild bats, normal mantises escaped capture whenever attacked, while mantises deaf to the bats' cries were almost always caught.
Designing quiet products—An acoustical overview
Authors: Lyon Richard H.
Published: October 2005

Product design is a multidisciplinary activity that combines scientific and technical understandings with product requirements and manufacturing process constraints to achieve an acceptable prototype. Within the design process there is a continuing interaction among all the requirements, such as structural integrity, lubrication, durability, appearance, etc. For acoustical goals to be achieved in this process, acoustical constraints and principles must be represented in the tradeoffs and compromises that are necessary in design. A major question is how these acoustical aspects are to come to the bargaining table. Very few design engineers understand acoustics deeply enough to know what is critical and what is not to meet product requirements, and very few noise control engineers have broad design experience. The author's own experiences in this area will form the basis for a discussion of these issues.
Reflection and transmission of spherical waves incident on a concentric spherical interface
Authors: Blackstock David T. , Morfey Christopher L.
Published: October 2005

The traditional analysis of sound reflection and transmission at an interface between two lossless fluids is for plane waves and a plane interface. Considered here is reflection and transmission of a spherical wave at a concentric spherical interface, either concave or convex. The pressure reflection (R) and transmission (T) coefficients are found to be complex; the coefficients for a convex interface are complex conjugates of those for a concave interface. Among the (somewhat surprising) results are these. First, although at high frequency the expressions for R and T are the same as for plane waves, at low frequency R→−1 regardless of the value of the ratio ρ2c2/ρ1c1, (provided ρ2≠ρ1). Second, perfect transmission requires both ρ2=ρ1, and c2=c1, not just ρ2c2=ρ1c1. Third, if the source is a monopole and the interface radius a→0, the sound power transmitted into the second medium is that expected for a single fluid; the same is not true, however, if the source is a dipole. [Work supported by ONR, NASA, and Southampton University.]
Effect of dispersion on a plane ultrasonic pulse
Authors: Morfey Christopher L.
Published: October 2005

Propagation through typical biological media involves dispersion as well as attenuation, since the attenuation coefficient varies with frequency more slowly than f2 in the ultrasonic range. Dispersion effects are explored for plane pulses in a homogeneous medium. The smoothing of an initially steplike pulse as it propagates through different attenuating media is illustrated numerically. Pulse waveforms are compared with and without allowance for dispersion, using a family of model α(f) curves. The associated dispersion in each case is obtained from the Kramers-Kronig relations, which ensure that the propagation transfer function is causal.
Acoustic scattering from porous aggregates
Authors: Chandra Kavitha , Thompson Charles
Published: October 2005

The interaction of acoustic waves in a two-phase biological medium characterized by randomly oriented porous aggregates is examined by direct solution of the integral equation representing the scattered and propagating field. The Born series is shown to converge in the limit as the compressibility variation is of order zero. However, pathological conditions exhibit a high degree of porosity requiring solutions to be carried out in the high compressibility limit. This results in a divergence of the perturbation series. By considering the Born series in an asymptotic sense, we obtain solutions by applying the optimal truncation rule and in extreme cases by an analytic continuation beyond the region of convergence by the method of Pade approximants. The present problem is of interest, in that angular measurements of the scattered field around the sample provides estimates of the characteristic pore sizes of the biological sample examined.
Normal hearing levels for an ER-3A insert earphone
Authors: Vavrek Michael J. , Frank Tom
Published: October 2005

Equivalent threshold sound pressure levels were obtained on each ear of 48 normal hearing adult subjects from 125–8000 Hz using TDH-49P earphones, referenced to a NBS-9A coupler, and ER-3A insert earphones, referenced to a HA-2 coupler. At each frequency (N = 9), the thresholds were significantly higher for the TDH-49P than for the ER-3A; however, the test versus retest and right versus left ear thresholds were not significantly different. The unadjusted ER-3A thresholds were in agreement with the reference equivalent threshold sound pressure levels (RETSPLs) reported by ISO [ISO 389, DAD 3, 1990]. After correcting for the subject's deviation from normal TDH-49P hearing levels and coupler (HA-2 to HA-1), the ER-3A thresholds were also in agreement with interim REISPLs reported by ANSI [ANSI S3.6-1989, Appendix G]. A complete data base concerning normative ER-3A thresholds will be presented and discussed in reference to the results of the present study, ISO and ANSI RETSPLs, and for future standardization.
Low- and high-frequency threshold reliability
Authors: Dreisbach Laura E. , Frank Tom
Published: October 2005

The purpose of this study was done to determine intrasubject low- and high-frequency hearing threshold reliability. Low-frequency (1, 4, 8 kHz) and high-frequency (10, 12, 14, 16, 18 kHz) thresholds were obtained on each ear of 30 normal hearing young adult subjects over four trials separated by i but no more than 2 weeks using a Beltone 2000 audiometer. At each frequency, the thresholds were not significantly different for the first versus second ear tested or for the four trials. Between trial threshold differences for each possible trial minus trial threshold combination (N = 6) were determined for each ear of each subject at each frequency. For the possible 2880 between trial threshold comparisons (6 trial combinations = 8 frequencies = 30 subjects = 2 ears), only 23 resulted in threshold differences ⩾ ± 11 dB. It was concluded that repeated intrasubject high-frequency thresholds were as reliable as for the lower frequencies. Clinical implications regarding high-frequency serial monitoring of hearing thresholds will be discussed.
Holographic measurement of power flow in large immersed structures
Authors: Clark Joseph A. , Honke Paul M. , Ellis J. Michael
Published: October 2005

Simple harmonic motions of a vibrating surface can be decomposed into two component motions: a standing wave, which corresponds to a characteristic mode shape, and a traveling wave, which is associated with the flow of power along the surface. Random motions of the vibrating surface can be decomposed into a series of simple harmonic motions, each of which can be decomposed into standing and traveling components. Holographic measurement of the pressure field around an immersed, point excited, vibrating cylinder have been processed to reveal the series of standing and traveling waves noted above. The results have been visualized in computer-generated movies and used to diagnose the structural response of the cylinder and power flow along and out of its surface. In this talk, the measurement, processing, and graphic display systems used to perform the diagnosis and features revealed by the investigation will be described.
Measurements of the acoustic vector wave field in the shallow ocean made by a single ocean sub-bottom seismometer (OSS)
Authors: Yamamoto Tokuo , Nye Thomas , Goodman Dean
Published: October 2005

In the shallow oceans, acoustic waves are strongly coupled with the seabed. If the vector wave field within the seabed is measured at a point, the direction of acoustic wave propagation can be accurately determined. To test this idea, we have measured the vector wave fields that are induced by ULF/VLF (0.01–1 Hz) ambient acoustic noise and acoustic pulses (0.05–1000 Hz) generated by an airgun using a single ocean sub-bottom seismometer in shallow water 13 m deep. The maximum entropy principle is applied to the three orthogonal components of the vector field induced by the ambient noise to calculate the directional spectra. We were capable of detecting the noise field propagating from many directions that were substantiated from other independent measurements. The measured acoustic vector wave field induced by a moving source were compared with the model predictions by a WKBJ code. In the model calculations, the geoacoustic data obtained from the bottom shear modulus profiler method (Yamamoto and Trevorrow, in this conference) were used. Excellent agreements are obtained between the measured seismograms and the synthetic seismograms indicating that moving acoustic sources can be accurately determined using only two OSSs in the shallow oceans. [Work supported by ONR.]
Experimental detection of a slow acoustic wave in sediment at shallow grazing angles
Authors: Boyle Frank A. , Chotiros Nicholas P.
Published: October 2005

Following recent experimental results at sea (N. P. Chotiros, Proc. Oceans '89) that suggest the existence of a previously undetected type of acoustic wave in sandy sediments, an experiment was designed to detect and measure the speed of acoustic waves in an isolated environment. The experiment was conducted in a laboratory tank containing 1 m of unwashed river sediment under a 3-m water column. Observations were made of the travel time and attenuation of a pulse from an acoustic source located above the water-sediment interface to a set of probes below the interface. It was observed that, at normal incidence the pulse traveled at about 1750 m/s, while at shallow grazing angles, the pulse traveled through the sediment at close to 1200 m/s. An interesting possible explanation exists in the Biot model [M. A. Biot, J. Acoust. Soc. Am. 28, 168–191 (1956)], which predicts a slow acoustic wave in porous materials. [Work funded by ONR under NOARL management.]
VLF bottom loss measurement: in the Blake-Bahama basin
Authors: Becklehimer Jeffrey L. , O'Hara Stephen , Bibee L. Dale
Published: October 2005

Broadband (8–25 Hz) measurements of ocean-bottom reflection loss were made using airgun sound sources and a vertical hydrophone array for grazing angles between 5 and 55 deg. Frequency-wavenumber analysis was used to partition the energy received by the hydrophone array into the energy spectrum due to the direct water path and that from the path with one bottom reflection. Bottom loss estimates were then calculated as the ratio of the energy spectrum from these two propagation paths. Comparisons of theoretical and measured reflection loss are made. An increase in bottom loss is observed near 35 deg and can be explained as a critical angle effect. [Work supported by Office of Naval Technology.]
Attenuation of low-frequency sound in the Black Sea
Authors: Browning David G. , Mellen Robert H.
Published: October 2005

Of the three chemical absorption mechanisms in seawater, only two (magnesium sulphate and boric acid) are dominant in most ocean areas. However, in some reduced salinity areas such as the Baltic Sea it has been found that the third mechanism (magnesium carbonate) can make a very significant contribution. An analysis is made of the chemical constituents of the Black Sea, which has a salinity that is approximately one-half that of standard seawater. The resulting values of low-frequency attenuation are computed utilizing the global attenuation model. These results are compared to values in the Baltic Sea and other ocean areas.
Radiated noise characteristics of M/V OVERSEAS HARRIETTE, a modern cargo ship
Authors: Arveson Paul T. , Vendittis David J.
Published: October 2005

Low-frequency ambient noise in the ocean is often influenced by radiated noise from merchant shipping. In an effort to quantify this noise, a series of extensive and carefully planned measurements were made of the radiated noise of M/V OVERSEAS HARRIETTE, a 25 525-deadweight ton 567-ft cargo ship powered by a direct-drive low-speed diesel engine. This ship and its power plant are typical of many modern merchant ships. The radiated noise data show high-level tonal frequencies from the ship's service diesel generator, main engine firing rate, and blade rate harmonics due to propeller cavitation. Directivity measurements taken at many angles under the ship indicate that the radiation is generally dipole in form at lower frequencies, as expected. There are some departures from this pattern that may indicate hull interactions. Blade rate fundamental levels show good agreement with predicted levels. [Work supported by NRL.]
Laurence Batchelder: Inventor and patent reviewer
Authors: Martin Daniel W.
Published: October 2005

An inventor for 23 U.S. patents, assigned to Submarine Signal Company and Raytheon Company, Batchelder contributed numerous inventive concepts to underwater sound transducers and arrays, and to systems for hunting, detection, and ranging. For 41 years he regularly reviewed for the Journal a total of 3035 patents on transducers, systems, and measuring devices, mostly in underwater sound, and contributed his last review only a month before his death. Examples from his patents and from his insightful reviews will be shown.
Sound intensity in the transducer near field
Authors: Tichy J.
Published: October 2005

On of the principal research domains of Larry Batchelder was transducers. This paper intends to contribute to this memorial session by summarizing the use of intensity technique for the analysis of sound radiation from transducers. Examples of near-field measurements will reveal how intensity technique can identify both the radiation of power and the acoustical coupling between various surface elements.
Laurence Batchelder's contributions to national and international standards
Authors: Lang William W.
Published: October 2005

Over a period that spanned more than 4 decades, Laurence Batchelder made significant contributions to the development of both national and international standards. With patience, good humor, and an untiring willingness to see the work completed, he participated as committee member and chairman in the preparation of many of the most important standards. His standards work started in the early days of the ASA's only standards committee, Z24, and continued through the ASA sectional committee S1 (acoustics), S2 (shock and vibration), S3 (bioacoustics), S12 (noise), to the chairmanship of ASACOS (ASA committee on standards). For many years, he chaired the ASME's Y10.15 committee on letter symbols for acoustics. In the international arena, he served lengthy tenures working for TC43 (acoustics) of the International Organization for Standardization (ISO) and as chairman of TC29 (electroacoustics) of the International Electrotechnical Commission (IEC). He headed U.S. delegations to plenary meetings of ISO/TC43 and IEC/TC29 for more than a decade. His influence on the development of both national and international standards was profound.
Design of a direct audio communicator for divers
Authors: Ranlet Richard W.
Published: October 2005

An underwater communicator was developed to evaluate the suitability of direct audio voice transmission as a practical means to enable close-range communications between divers using open-circuit SCUBA. A communicator that transmits speech directly into the water through an omnidirectional acoustic projector was designed and human engineered to yield a practical working prototype suitable for normal open-water dive conditions. This system requires no specialized equipment to enable reception by either submerged swimmers or divers. A series of in-water tests was carried out as an intrinsic part of the design evolution of the device. Once the design was finalized, intelligibility of the communicator was measured by underwater audiological testing using tones, phonetically balanced word lists, and sentence lists. Results indicate average word list intelligibility of 82% correct responses and sentence list intelligibility of nearly 100% (both at 5-m range). Open-water range tests showed comfortable communication range between divers using the device to be greater than 140 ft (43 m) in calm seas. [Work was performed as part of a Master of Science thesis in Ocean Engineering at the University of Rhode Island.]
Normalization process in the human auditory system
Authors: Cho Jennifer L. , Hall Michael D. , Pastore Richard E.
Published: October 2005

Irrelevant variability of source characteristics imposes problems in maintaining perceptual accuracy of an intended message. The perceptual system appears to adjust for differences between sources in a time-consuming manner called normalization which has been investigated with speech stimuli. The present experiment sought to establish auditory normalization with music stimuli using an AX chord discrimination task. Stimuli consisted of four chords produced by five different instruments. Degree of instrument variability was manipulated within subjects by presenting stimuli in three normalization blocks: single instrument, multiple instrument, and multiple-mixed instrument. In these conditions instrument selection remained the same throughout a block of trials, differed across trials, or differed within and across trials. Significant expected differences in response latencies and task accuracy were observed for trials that were composed of different instruments, compared to trials having the same instrument. Results clearly indicate normalization in the perception of music. [Work supported by NSF.]
Recent progress in outdoor sound propagation prediction by the parabolic equation method
Authors: Gilbert Kenneth E. , Di Xiao , You Chulsoo
Published: October 2005

During the past 5 years significant progress has been made in predicting long-range sound propagation in the atmosphere using numerical methods based on the parabolic approximation to the Helmholtz equation. The theory for the parabolic approximation is discussed starting from the one-way wave approximation to the two-way (Helmholtz) wave equation. The application of the theory for practical numerical algorithms is briefly reviewed, and some results are presented for sound propagation in a turbulent atmosphere. Finally, a new Green's function approach to the parabolic equation is presented. The new method is approximately 100 times faster than existing parabolic equation methods for outdoor sound propagation. Hence the new algorithm has the potential for useful calculations in the field using a desktop computer. [Work supported by NASA.]
The manifestation of certain classes of resonances as standing waves on elastic shells
Authors: Werby M. F. , Überall H.
Published: October 2005

In an earlier work it was shown that certain classes of resonances excited on elastic solids correspond to standing-wave patterns on the object surface. The observation was in fact implicit in the circumferential nature of such resonances made clear by the early theoretical works of Überall et al. and the experimental work of R. Goodman et al. The demonstration was made possible by subtracting the rigid background (in partial wave space) using the background proposed by Flax, Überall, and Dragonette for elastic solids. The background for elastic shells introduced in the upcoming book by Überall on resonance scattering now makes it possible to demonstrate that this is also observed for Lamb-type resonances and this fact will be demonstrated for several submerged elastic shells.
Monaural spatial resolution in the horizontal plane under dynamic and static listening conditions
Authors: Grantham D. Wesley , Chandler David W.
Published: October 2005

Auditory spatial resolution was measured in the horizontal plane for three normal-hearing adult subjects in a darkened anechoic chamber. In all conditions, subjects' right ears were occluded by an EAR foam insert plug plus an external sound-attenuating muff, providing a total of about 40 dB of attenuation. In the dynamic conditions, the minimum audible movement angle (MAMA) was measured—that is, the angular extent a moving target had to traverse to be just discriminable from a stationary target. In the static conditions, the minimum audible angle (MAA) was measured—that is, the minimum angular separation between two sequentially presented stationary targets that was just discriminable from a single stationary target presented twice in succession. In general, MAMAs and MAAs decreased as stimulus bandwidth increased from 0 Hz (pure tone at 3000 Hz) to wideband. MAAs were extremely variable across and within subjects (varying from 10° to 40° of arc). MAMAs for slow-velocity targets (10°/s) were usually lower than MAAs measured for the same signals, a result that contrasts with the results from binaural resolution tasks [D. W. Chandler and D. W. Grantham, J. Acoust. Soc. Am. Suppl. 1 87, S64 (1990)]. These results suggest that specialized mechanisms sensitive to dynamic stimuli may play a role in monaural spatial resolution. [Work supported by NIH.]
Differential lateralization interference for interaural time and interaural level differences
Authors: Heller Laurie M. , Richards Virginia M.
Published: October 2005

Lateralization thresholds were obtained in a 21FC task using 200-ms noise bands presented with either an interaural time or level difference. The elevation in lateralization threshold (interference) caused by a simultaneously presented noise band was measured. When the ITD was applied to a 50-Hz-wide noise band centered at 500 Hz, there was minimal interference from a diotic 400-Hz-wide noise band centered at 4000 Hz. When the ITD was applied to the noise band centered at 4000 Hz, there was substantial interference from a diotic band of noise centered at 500 Hz [D. Mcfadden and E. G. Pasanen, J. Acoust. Soc. Am. 59, 634–639 (1976)]. In contrast, the interfering effect of a diotic noise band was greater when the ILD was applied to the 500-Hz band of noise than when it was applied to the 4000-Hz band of noise. A similar pattern of results was obtained when the ITD or ILD of the interfering band of noise was randomized from interval to interval, although randomization produced greater interference in all conditions. The complementary pattern of results for time and level differences favors an explanation based on averaging between simultaneous interaural parameters rather than a masking-based explanation.
Modeling of binaural discrimination of multiple sound sources: A contribution to the development of a “cocktail party processor”
Authors: Slatky H.
Published: October 2005

The human hearing system when being stimulated simultaneously by narrow-banded signals from two loudspeakers at different locations is able to determine the directions of both sound sources. However, conventional models of binaural interaction which are based on interaural cross correlation in critical bands fail in discriminating the source directions. The reason is that the cross-correlation functions at the output of the model display severe fluctuations in time. A revised binaural cross-correlation model that contains an additional “recomputation mechanism” will be presented. This mechanism estimates directions and energies of sound sources from cross-correlation functions fluctuating in time. Using this mechanism the results of relevant auditory experiments can be reproduced. This model has been applied to construct a cocktail party processor, which is able to enhance the signal-to-noise ratio considerably.
Are articulations integrated in the perception of vowel height?
Authors: Kingston John
Published: October 2005

Using the Garner paraidgm [W. Garner (1974)], Kingston [Phonetica (in press)] demonstrated that the acoustic effects of differences in velum height (the frequency separation of the nasal pole and zero =nasalization) and rate of vocal fold vibration (fundamental frequency) which covary with tongue height in vowels are integrated perceptually with the acoustic effect of that articulation (first formant frequency), perhaps because they exaggerate the perceptual value of the latter articulation. The failure to separate perceptually the acoustic effects of these three articulations challenges the claim of direct realists [e.g., C. Fowler, J. Phonet. 14, 3–28 (1986)] that articulatory gestures are the objects of speech perception, but in only a limited way, since the stimuli were brief and simple enough that they may not have allowed listeners to attribute these acoustic effects appropriately to their articulatory sources. Experiments are currently in progress to test whether similar perceptual integration occurs even when other aspects of the stimuli would allow the acoustic effects to be attributed to coarticulation [R. Krakow et al., J. Acoust. Soc. Am. 83, 1146–1158 (1988)], e.g., is nasalization integrated with first formant frequency in nasal as well as oral consonant contexts? Integration will also be tested more rigorously than in the earlier work, using precepts of signal detection theory.
Auditory-perceptual interpretation of vowels and diphthongs: A progress report
Authors: Miller James D.
Published: October 2005

The auditory-perceptual interpretation of vowels [Miller, J. Acoust. Soc. Am. 85, 2114–2134 (1989)] will be reviewed briefly and a similar approach to diphthongs, based on spectral glides, will be presented. The relations between acoustic descriptions in the auditory-perceptual space and articulatory descriptions will be outlined. Also, issues relating to the roles of formants versus spectral patterns and the precise meaning of target zones will be presented. The distinction between target zones for vowels produced as steady states as opposed to target zones for vowels produced as spectral glides will be emphasized. Preliminary criteria that may serve to distinguish these will be mentioned. Finally, recent data, which appear to be consistent with the auditory-perceptual approach, will be presented.
“Correction” in the perception of filtered vowels
Authors: Shriberg Elizabeth E. , Ohala John J.
Published: October 2005

Two studies examined the effect of cues to channel characteristics on listeners' perception of low-pass-filtered (1000-Hz) vowels. In experiment 1, 85-ms steady-state portions of 11 English vowels excised from digitized natural speech were preceded by a sentence. Following an ulfiltered sentence, filtered front vowels were largely perceived as back vowels; however, following a filtered sentence, the effect was reduced, and front vowels were “corrected” at high rates (χ2= 108.45, p < 0.001). In experiment 2, the sentence was eliminated and a “masker” was added to the filter-reject region of the stimuli; again, a striking increase in front-to-back confusions occurred when [vowels were filtered, and a decrease in these errors occurred when high-frequency noise was added to the filtered vowels (χ2 = 63.74, p < 0.001 ). in both experiments, a small but stable increase in back-to-front errors in conditions containing cues to filtering was also observed. Results suggest that in these conditions, but not in those lacking cues, listeners deter- mined which filtered vowels were actual front vowels.
Influence of a syllable's form on the perceived internal structure of voicing categories
Authors: Volaitis Lydia E. , Miller Joanne L.
Published: October 2005

The role of syllable structure on voice-onset time (VOT) was examined by comparing VOT values in consonant-vowel (CV) and consonant-vowel-consonant (CVC) syllables, across a range of speaking rates. In a production study, when CV and CVC syllables were equated for overall duration, VOT values were found to be consistently shorter for the CVC than the CV syllables. Furthermore, when syllables were equated for CV duration, VOT values for CV and CVC syllables tended to be equal, suggesting that speakers were producing VOT values with regard to the syllable's CV duration. In a subsequent perception study, listeners adjusted for these changes in VOT by altering three aspects of category structure in relation to the syllable's CV duration, and not to its overall duration — the location of the voiced — voiceless category boundary, the upper limit of the voiceless category, and the range of “good” exemplars that lies between those two boundaries. These findings support the notion that listeners perceptually restructure their phonetic categories so as to accommodate changes in VOT that occur in production as a result of the syllable's phonological context, as”well as its speaking rate. [Work supported by NIH.]
An investigation of locus equations as a source of relational invariance for stop place categorization
Authors: Sussman Harvey M.
Published: October 2005

Locus equations were investigated as a potential higher-order metric capable of illustrating relational invariance for place of articulation in voiced initial stop consonants independently of vowel context. Locus equations are straight-line regression fits to data points formed by plotting onsets of F2 transitions along the y axis and their corresponding midvowel nuclei along the x axis. Twenty subjects, 10 male and 10 female, produced /b/v/t/, /d/v/t/, and /g/v/t/ tokens for 10 vowel contexts. Each CVC token was repeated in a carrier phrase five times yielding 150 tokens per subject. Formant measures were obtained using the MacSpeech Lab II speech analysis system. Locus equation scatter-plots revealed extremely tight clustering of points around the regression line that were consistent across speakers and gender. Derived slope and y-intercept parameters were significantly different across stop place categories. The relative value of F2onset as it linearly changes in relation to the coarticulatorily produced vowel reflects an acoustic correlate of relational invariance for stop place. A discriminant analysis using F2onset & vowel as predictors showed 82%, 78%, and 67% classification rates for labial, alveolar, and velar place. Using derived slope and y-intercept values as predictors led to 100% classification into stop place categories. A neurobiologically oriented perspective on the invariance issue is explored and a brain-based recognition algorithm for stop place integrating burst and F2 cues is offered. [Work supported by NSF.]
Uncertain field signal processing
Authors: Richardson Anthony M. , Nolte Loren W.
Published: October 2005

Classical matched-field processing assumes a known ocean environment and known array sensor positions. It is well known that source localization using this method can be quite sensitive to this knowledge. The uncertain field processor approach is based on signal detection and estimation theory and allows one to incorporate, a priori, the uncertainties in the sound-speed profile and/or the array sensor positions. This approach is illustrated for several specific situations for a deep ocean environment. [Work supported by ONR and North Carolina Supercomputing Facility.]
Broadband modeling and source localization of a PRN projector tow
Authors: Westwood Evan K.
Published: October 2005

A broadband ray model is used to simulate data from a deep water experiment (TAGEX 87) in which a pseudo random noise (PRN) source is towed past a 24-element, bottom-moored array. The source spectrum contains a series of evenly spaced lines from 60–100 Hz. Simulated shade plots of received spectrum level versus frequency and time exhibit excellent agreement with the data. A broadband matched field algorithm is used to localize the source in range as a function of time. The algorithm consists of matching the recorded cross spectrum R1R2* between two phones with simulated cross spectra S1S2* at a series of ranges. The correlations between recorded and simulated cross spectra are added coherently as a function of frequency to obtain the localization matrix entry: Lij = Σf[RliR2i*] [SljS2j*]*. Successful localizations of the PRN source are obtained at ranges from 0–30 km. [Work supported by Naval Ocean Systems Center, Code 733, under contract N00039-88-C-0043-1-43.]
A new technique for detecting Gaussian signals in non-Gaussian noise
Authors: Poor H. Vincent
Published: October 2005

The signal and noise processes arising in passive underwater acoustic detection are usually modeled as being random processes, with the dominant noise often being best modeled as a non-Gaussian process [H. V. Poor and J. B. Thomas, J. Acoust. Soc. Am. 63, 75–80 (1978] due to the effects of noise phenomena resulting from sources such as cracking ice, marine animals, or surface shipping. A new technique for the detection of Gaussian signals that can be modeled as being produced by linear stochastic systems, in the presence of such non-Gaussian noise, has been developed. This technique is based on an approximation to the likelihood-ratio statistic [H. V. Poor, An Introduction to Signal Detection and Estimation (Springer-Verlag, New York, 1988)] for such situations. This likelihood-ratio approximation is in turn based on the Masreliez approximation of nonlinear filtering [R. Vijayan and H. V. Poor, IEEE Trans. Commun. 38, 1060–1065 (1990)], in which the predicted state probability density (i.e., the time update) of the underlying stochastic system is approximated with a multivariate Gaussian distribution. This approximation allows calculation of the likelihood-ratio statistic using a pair of sufficient statistics satisfying a simple nonlinear recursion. An approximation to the locally optimum detection statistic [Poor, op. cit.] for this situation has also been derived, by considering the limiting behavior of the approximate likelihood-ratio statistic as the signal-to-noise ratio vanishes. [Work supported by the U.S. Office of Naval Research under Grant N00014-89-J-1321.]
Application of sound to underwater acoustics
Authors: Pitre R. , Krout Timothy L. , Perkins John S. , McDonald B. Edward , Kuperman W. A. , Collins Michael D. , Makris Nicholas C. , Gibian G. L.
Published: October 2005

Experienced sonar operators can recognize various types of sounds. With the recent developement of time-domain underwater acoustics models and computer workstations capable of generating high-quality sounds from digital data, it is now possible to train the human ear to associate a wide variety of sounds with the underlying physics. With sufficient training, it might be possible to perform qualitative inversion problems such as estimating the range of a sound source, determining properties of the ocean sediment from a bottom-reflected signal, and recognizing the source of a scattered signal. Digitally generated sound can also be used in connection with time-domain signal-processing algorithms such as the delay-and-sum beamformer and the simulated annealing optimal beamformer [W. A. Kuperman et al., J. Acoust. Soc. Am. 88, 1802–1810 (1990)]. The synthesized sounds presented will include propagation to various ranges in different ocean environments, reflection from different types of ocean bottoms, scattering from bubble clouds near the ocean surface, and the application of beamforming to extract signals from interference (including a single speaker in a noisy crowd).