bluuebunny/crossref_metadata_2025 huggingface dataset:
Jozef Zwislocki in the post-von Bekesy era of cochlear physiology
Authors: Rhode William S.
Published: October 2013

Professor Joe Zwislocki is a rare individual who has a strong background in mathematics and hydrodynamics that he applied to the physiological characterization of cochlear function. Realizing the preeminent need for more accurate measurements of cochlear mechanical properties, he undertook the study of properties of the tectorial membrane (TM). His measurements are unique in that they remain the only in vivo measurements of stiffness of the TM. In 1979, he introduced longitudinal effects into cochlear modeling that today has been shown to result in realistic cochlear mechanical transfer curves. A difference between the filter properties seen in auditory nerve fibers and basilar membrane (BM) mechanics led to a leading theory of separate resonances for organ of Corti and TM. He developed a model of how this would affect the shear motion between the TM and reticular lamina. Additional studies were undertaken that substituted recordings in the cells of Hensen for the very difficult direct observation of BM mechanics that epitomize the ingenuity and resourcefulness of Joe Zwislocki.
Jozef Zwislocki’s contribution to the understanding of cutaneous sensation
Authors: Bolanowski Stanley J.
Published: October 2013

Whereas Professor Zwislocki is well known for his theoretical and experimental activities that discovered many principles about the auditory system as outlined in this special session, his influence on research efforts and contributions to the knowledge base of the cutaneous sensory system has not been as widely appreciated. Philosophically, he believes that all of the sensory systems have common, as well as different capabilities, and it is this philosophy which led him to explore many of the underlying factors behind somatosensation. This presentation will outline his scientific and philosophical input to the understanding of somatosensation from the level of receptor function to higher cognitive aspects. For example, he has influenced various views regarding tactile psychophysical thresholds and the relationships between sensation magnitude and the Differenz Limen. His theories on temporal summation and thoughts regarding independent tactile channels of communication originating in the periphery and passing on to the central nervous system will also be discussed. Physiologically he was a prominent player in determining transduction mechanisms of one of the prototypical mechanoreceptors found within the skin, the Pacinian corpuscle. Indeed, how somatosensation comes about has progressed greatly from his oftentimes unrealized influence.
Effects of response format on speech intelligibility in noise: Results obtained from open-set, closed-set, and delayed response tasks
Authors: Clopper Cynthia G. , Tierney Adam T. , Pisoni David B.
Published: October 2013

Many word recognition studies over the last 40 years have used forced-choice closed-set tasks, based on the assumption that closed-set and open-set tasks differ only in the level of chance performance. However, Sommers, Kirk, and Pisoni (1997) found that lexical competition and talker variability produce robust effects on performance only in open-set tasks, suggesting fundamental differences in the task demands and processing strategies between open- and closed-set tasks. In the present study, listeners were asked to recognize spoken words degraded by a bit-flipping algorithm in three response formats: open-set, closed-set ‘‘before,’’ and closed-set ‘‘after.’’ In the closed-set ‘‘before’’ condition, the six response alternatives were presented 1 s prior to the onset of the auditory signal. In the closed-set ‘‘after’’ condition, the response alternatives were presented 1 s after the auditory signal. Results revealed significant effects of lexical competition and talker variability only in the open-set task. These findings suggest that even a delay of 1 s is not adequate to induce the task demands observed in open-set word recognition tests. [Work supported by NIH.].
Perceptual discontinuities and categorization: Implications for speech perception
Authors: Holt Lori L. , Lotto Andrew J. , Diehl Randy L.
Published: October 2013

Behavioral experiments with infants, adults and nonhuman animals converge with neurophysiological findings to suggest that there is a discontinuity in auditory processing of stimulus components differing in onset time by about 20 ms. This discontinuity has been implicated as a basis for boundaries between speech categories distinguished by VOT. Here, we investigate how this discontinuity interacts with the learning of novel perceptual categories. Adult listeners were trained to categorize a nonspeech acoustic cue that mimics the temporal distinction of VOT. One group of listeners learned categories with a boundary coincident with the perceptual discontinuity. Another group learned categories defined such that the perceptual discontinuity fell within a category. Listeners in the latter group required significantly more experience to reach criterion categorization performance. The evidence of interactions between the perceptual discontinuity and the learned categories extended to generalization tests as well. It has been hypothesized that languages make use of perceptual discontinuities to promote perceptual distinctiveness among sounds within a language inventory. The present data suggest that these influences interact with category learning. As such, learnability may play a predictive role in selection of language sound inventories. Moreover, it may be possible to observe predictable learning effects in infant speech perception.
Perceptual prothesis in native Spanish speakers
Authors: Theodore Rachel M. , Schmidt Anna M.
Published: October 2013

Previous research suggests a perceptual bias exists for native phonotactics [D. Massaro and M. Cohen, Percept. Psychophys. 34, 338–348 (1983)] such that listeners report nonexistent segments when listening to stimuli that violate native phonotactics [E. Dupoux, K. Kakehi, Y. Hirose, C. Pallier, and J. Mehler, J. Exp. Psychol.: Human Percept. Perform. 25, 1568–1578 (1999)]. This study investigated how native-language experience affects second language processing, focusing on how native Spanish speakers perceive the English clusters /st/, /sp/, and /sk/, which represent phonotactically illegal forms in Spanish. To preserve native phonotactics, Spanish speakers often produce prothetic vowels before English words beginning with /s/ clusters. Is the influence of native phonotactics also present in the perception of illegal clusters? A stimuli continuum ranging from no vowel (e.g., ‘‘sku’’) to a full vowel (e.g., ‘‘esku’’) before the cluster was used. Four final vowel contexts were used for each cluster, resulting in 12 sCV and 12 VsCV nonword endpoints. English and Spanish listeners were asked to discriminate between pairs differing in vowel duration and to identify the presence or absence of a vowel before the cluster. Results will be discussed in terms of implications for theories of second language speech perception.
Neighborhood effects on speech-perception abilities of adults and children aged 6–9 years
Authors: Sussman Joan E. , Dee Devon , Curcio Diana
Published: October 2013

According to Luce and Pisoni (1998), the mental lexicon is organized into sparse and dense neighborhoods. In perception studies with adults, typically words from sparse neighborhoods are more quickly identified than words from dense neighborhoods, likely due to a competition effect. In production however, words from dense neighborhoods are produced more quickly than words from sparse neighborhoods, probably due to a faciliation effect. In young children, these so-called ‘‘neighborhood effects’’ have been shown to be absent (Charles-Luce and Luce, 1990), related to the overall smaller size of the lexicon. The current investigation studied single-feature perception by 10 children, aged 6–9 years and 10 adults, looking at differences due to neighborhood density. Each target word was presented in one of two semantically neutral carrier sentences in three levels of babbled noise: no noise, +5-dB S/N ratio, and 0-dB S/N ratio (equal signal and noise levels). Results showed that children performed best in quiet and that words from dense neighborhoods were perceived more accurately than those from sparse neighborhoods except for the 0-dB condition. Adults surprisingly performed best in the +5-dB condition and a neighborhood effect shown only for the 0-dB condition.
A labial gesture for /l/
Authors: Campbell Fiona , Gick Bryan
Published: October 2013

Both in language change and in substitutions during language acquisition and disordered speech, /l/ has often been observed to alternate with labial sounds such as [w] or rounded vowels, particularly in postvocalic position. While there are many possible explanations for this alternation, including acoustic enhancement and articulator coupling, one possibility that has not been tested is whether normal adult speakers of English actually produce lip rounding for /l/. A study was conducted to test for the presence of a labial gesture in normal productions of /l/. Front and side video data of lip positions were collected from three adult English speakers during productions of /l/ and /d/. Significant differences were found for all subjects in lip protrusion (upper and lower) and/or lip aperture (horizontal and vertical) in post-vocalic allophones, as well as between the pre- and post-vocalic allophones of /l/. No significant differences were observed in comparisons of pre-vocalic /l/ and /d/. Results suggest that there is in fact a labial gesture in the post-vocalic allophone of /l/, but not in the pre-vocalic allophone. These findings are consistent with a notion of gestural simplification as a possible explanation for substitutions and in language change. [Research supported by NSERC.]
The effect of physical constraints on articulatory variability in English /r/
Authors: Brown Jason , Gick Bryan
Published: October 2013

In a recent study of American English /r/, Guenther et al. [J. Acoust. Soc. Am. (1999)] hypothesized that articulatory ‘‘tradeoff’’ correlations are the result of the need to maintain stable acoustic targets. Their findings included (1) a positive correlation between tongue back height and tongue front horizontal position for 7/7 subjects, (2) a negative correlation between tongue back height and tongue front height for 5/7 subjects, and (3) a positive correlation between tongue front horizontal position and tongue front height for 2/7 subjects. The present study investigates the possibility that these correlations result from physical constraints on the tongue such as volume preservation and palate angle. Continuous sentences from the Wisconsin x-ray microbeam database were analyzed to determine whether these same correlations were present across whole utterances presumably lacking a stable F3 target. Results to date show some significant correlations despite extremely high noise levels. Results will be presented for additional measures using vowels only to reduce noise. These initial results suggest that the observed correlations may not result from strict acoustic targets for /r/, but rather from internal and external physical constraints on the tongue. [Work supported by NSERC and NIH.]
Hearing smiles and smile suppression in natural speech
Authors: Drahota Amy K. , Reddy Vasudevi
Published: October 2013

That we can hear smiles in speech is an established finding. However smiles in natural speech can be of many different kinds, serving different social functions. Previous research has focused only on one category of smile using either smiles ‘‘posed’’ during speech or degraded samples of smiling speech (to disguise the content of utterances). The present study used naturally occurring speech in three foreign languages (Czech, Spanish, and Finnish) and in English, presented to naive native English speakers. Preliminary analyses extracted two kinds of smiles in speech—‘‘open smiles’’ and ‘‘suppressed smiles’’ in contrast to speech with ‘‘no smiles.’’ Eighty listeners were presented with 18 audio-clips (six of each type) in randomized order. ‘‘No smiles’’ and ‘‘open smiles’’ were successfully identified across all languages. ‘‘Suppressed smiles’’ were most often coded as ‘‘no smiles.’’ An exploration of the pitch contours showed that ‘‘suppressed smiles’’ had a higher average pitch similar to ‘‘open smiles,’’ but a significantly higher variance in pitch range than others. Natural speech produces smiles serving very different functions. The auditory expression and perceivability of emotion is likely to be influenced by subtle social functions only evident in natural interactions.
Phase alignment for coherent and vector processing
Authors: Wagstaff Ronald A.
Published: October 2013

Acoustic phase angle is seldom used to achieve signal-to-noise ratio (SNR) gain for single sensor and beam spectral output. One reason is that phase angles generally progress at a nonuniform rate, with unpredictable changes in the direction of rotation. This causes fluctuations in the phase angles with corresponding reductions in gain, often including severe attenuation and cancellation of signals. By adopting a particular analytically convenient definition for phase fluctuations, the fluctuations, thus defined, constitute a set of aligned-phase angles. The aligned-phase angles can be used instead of phase angles to form phase-aligned coherent and vector averages. Doing so achieves SNR gains that equal or exceed the theoretical value of 10 log(N) for perfectly coherent vector averaging (N is the number of elements averaged). This is accomplished without the signal attenuation and cancellation common to coherent and vector averaging. Furthermore, the aligned-phase angles can also be used to automatically detect signals, based on both phase-aligned coherence and appropriate averaging of the aligned-phase angles. Results are included for wind noise in outdoor measurements. [Work supported by U.S. Army Space and Missile Defense Command.]
From acoustic observatories to robust passive sonar
Authors: Baggeroer Arthur B.
Published: October 2013

The evolution of the DARPA Robust Passive Sonar (RPS) as well as the ONR Shallow Water Acoustic Testbed (SWAT) programs can be traced from concept of an acoustic observatory posed by Munk in 1980 through several assessment and feasibility studies to their current implementations. During this, the thinking on several key hypotheses matured. (i) Are noise fields directional enough to sustain high array gains? (ii) What are the tradeoffs among nonstationarity caused by ship motion, array configuration (geometry and the number of sensors), and ‘‘snapshots’’ needed for stable adaptive processing? (iii) What is the interaction between gains from vertical and horizontal apertures? (iv) How much signal gain degradation is acceptable? (v) What methods of post-processing can be done for normalization, tracking, and 3-D localization? This presentation will give a brief summary of the history of RPS and SWAT and pose the question of how well we can answer some of hypotheses which motivated them.
Adaptive sonar detection performance prediction in an uncertain ocean
Authors: Book Paul , Krolik Jeffery , Kraut Shawn
Published: October 2013

This paper addresses the problem of predicting detection performance when the signal wavefront is uncertain and the noise field directionality is unknown. Passive sonar detection in this scenario typically involves robust adaptive beamforming with limited training data. The classical sonar equation, however, assumes the noise field and signal wavefront are known exactly. In this paper, we use the statistics of the generalized likelihood ratio test (GLRT) for the composite hypothesis of a multirank signal in Gaussian noise with unknown covariance matrix to evaluate the detection threshold (DT) as function of ocean uncertainty and number of noise training snapshots. Further, the trade-off between array gain (AG) and detection threshold (DT) is studied as a function of training sample size in a dynamic interference environment. Detection performance of the GLRT is characterized in terms of bounds on the middle 80th percentile of classical passive sonar figure of merit (FOM) and range-of-the-day (RD) over an ensemble of ocean environments. Different classes of environments including downward refracting and upward refracting scenarios are examined with particular attention to the Florida Straits region. Example performance prediction bounds are presented using real horizontal noise field and environmental data. [Work supported by ONR.]
Quantification of deterministic matched-field source localization error in the face of random model inputs
Authors: Daly Peter M. , Hebenstreit Gerald T.
Published: October 2013

Deterministic source localization using matched-field processing (MFP) has yielded good results in propagation scenarios where the nonrandom model parameter input assumption is valid. In many shallow water environments, inputs to acoustic propagation models may be better represented using random distributions rather than fixed quantities. One can estimate the negative effect of random source inputs on deterministic MFP by (1) obtaining a realistic statistical representation of a signal model parameter, then (2) using the mean of the parameter as input to the MFP signal model (the so-called ‘‘replica vector’’), (3) synthesizing a source signal using multiple realizations of the random parameter, and (4) estimating the source localization error by correlating the synthesized signal vector with the replica vector over a three dimensional space. This approach allows one to quantify deterministic localization error introduced by random model parameters, including sound velocity profile, hydrophone locations, and sediment thickness and speed. [Work supported by DARPA Advanced Technology Office.]
Sensorless control of a harmonically driven linear reciprocating electrodynamic machine for a thermoacoustic refrigerator
Authors: Shearer Tony L. , Smith Robert W. M. , Hofmann Heath F. , Garrett Steven L.
Published: October 2013

In electrically driven thermoacoustic refrigerators, the acoustic pressure and actuator displacement are typically monitored while a nominally harmonic drive frequency is adjusted to achieve a given operating point (e.g., maximum electroacoustic conversion efficiency, acoustic resonance, maximum power, etc.) Most often, pressure and displacement are measured directly, using sensors. Using a model of the electrical and mechanical dynamics of a linear electrodynamic machine and resonant assembly, the actuator displacement and pressure at the piston can be accurately estimated via direct measurement of the voltage and current at the machine terminals. This provides a means for sensorless control of the machine. The estimation method and system parameter extraction method will be described, as well as results of comparisons to sensors. Results from tests on a thermoacoustic refrigerator operating at 3-kW acoustic input power using a sensorless control system implemented to maintain an acoustic resonance will be shown, wherein the refrigerator cold temperature was varied over a practical operating range. The control system tracked the acoustic resonance frequency and achieved the desired phase relationship between pressure and displacement to within 3 deg based on the estimation, thus maintaining essentially optimal electroacoustic conversion efficiency during the test. [Work sponsored by ONR.]
Numerical modeling of inert gas-condensing vapor thermoacoustic engines
Authors: Slaton W. V. , Raspet Richard , Hiller Robert A.
Published: October 2013

Recent theoretical work by Slaton and Raspet et al. describe the acoustic propagation equation [J. Acoust. Soc. Am. 114, 1414–1422] and the second-order enthalpy and mass transport equations [J. Acoust. Soc. Am. 114, 1423–1430] for an inert gas-condensing vapor mixture in a porous medium with an imposed temperature gradient. The acoustic propagation and enthalpy transport equations show that the vapor diffusion effects in the mixture are analogous to the heat diffusion effects in the thermoacoustics of inert gases, and that these effects occur in parallel with the heat diffusion effects in the wet system for proper choice of inert gas and vapor. Writing the acoustic propagation equation as two coupled first-order differential equations in terms of the volumetric velocity and acoustic pressure amplitude and utilizing the conservation of enthalpy in the stack allows the system of equations to be solved numerically by interfacing with the well-established thermoacoustic modeling code, DeltaE. Modeling of various thermoacoustic engines utilizing an inert gas-condensing vapor working fluid will be presented. It will be shown how the COP relative to Carnot and the heat pumping power for thermoacoustic refrigerators can be increased significantly by proper choice of gas mixture. [Work supported by ONR.]
Impedance tube measurements of thermoviscous functions with a condensable working fluid
Authors: Brown D. C. , Hiller R. A. , Raspet R.
Published: October 2013

Theoretical work by Slaton et al. [J. Acoust. Soc. Am. 112, 1414–1422 (2002); 112, 1423–1430 (2002)] develops the linear theory for thermoacoustics when the working fluid has a component which undergoes condensation and evaporation on the stack during the acoustic cycle. In order to test these ideas an impedance tube is used to measure the acoustic impedance in a closed-end driver-pipe system which contains a sample stack. The impedance is measured on the driver side of the stack from pressure measurements of two closely spaced microphones. This may be compared to the impedance computed from a numerical integration from the closed end of the pipe through the stack, using the known or assumed values of the thermoviscous dissipation functions in the stack. Measurements and the theory for a variety of stack materials and working fluids will be presented.
Effects of auralization technique and cross-modal visual stimulus on auditory localization in virtual environments
Authors: Henderson Paul D. , Torres Rendell R. , Shimizu Yasushi , Radke Richard , Lonsway Brian
Published: October 2013

The performance of auditory localization in audiovisual environments is affected by both the complexity and congruence of the auditory and visual sensory inputs. Subjects were asked to identify the perceived location of a virtual acoustic source placed at varying positions in the horizontal plane and rendered by either conventional stereophonic reproduction or through wavefront reconstruction by a loudspeaker array. The virtual source was auralized in simulated reflective and anechoic acoustic environments both with no visual stimulus and with projected imagery of varying congruence. The localization precision of subjects presented with complex aural stimuli in the form of simulated reflective environments is reduced relative to anechoic conditions. Additionally, array-based wavefront reconstruction provides a significant increase in overall localization performance over stereophonic rendering, particularly for subjects positioned off the primary axis of the loudspeaker array. Subjects presented with simultaneous aural and visual inputs are able to accurately locate the virtual sound source when a large incongruence angle exists (typically more than 30 degrees). However, in the presence of a smaller angular separation between stimuli, a bias towards the visual stimulus is detectable. The results help determine the requirements for accuracy in auralization and reproduction in the creation of virtual multimedia environments.
Acoustics of a broadcast center
Authors: Beristain Sergio
Published: October 2013

A broadcast system in Mexico City had to change facilities in order to concentrate in a single site all related broadcast stations and production studios in order to facilitate its normal operation. This led to a design which included the acoustic noise isolation and the interior acoustics of every studio and control room, together with the audio interconection, the electricity layout, the air conditioning system, the office building, etc. This paper presents the acoustics profile of the center, including final results of the construction as they were measured on completion of the installation. The complex has seven AM and FM broadcast stations, plus seven production studios for news, commercials and radio-novels plus an audio master control room, and everything was completed within four months.
The chorus environment and the shape of communication systems in frogs
Authors: Marshall Vince
Published: October 2013

Many species of frogs breed in dense and structurally complex aggregations of calling males termed choruses. Females entering a chorus are faced with the tasks of recognizing and locating mates on the basis of their advertisement calls. The chorus environment poses particular challenges for communication as signalers and receivers will face high levels of background noise and interference between signals. For females, such conditions may decrease the efficiency of communication, with the consequences of increasing the time required to find a mate or errors in mate choice. For males, it will give rise to intense competition for the attention of females. Additionally, the chorus environment for a species is not static, and will vary over both spatial and temporal scales. This complex and dynamic environment has shaped the signals and signaling behaviors of frogs in sometimes surprising ways. In this talk, some of the implications of the chorus environment for both receivers and signalers is discussed. In particular, examples from North American hylid frogs are drawn upon and research on the role of signal timing in influencing the responses of females and plasticity in aggressive behavior between neighbors in choruses are discussed.
Patterns of fish sound production
Authors: Mann David A.
Published: October 2013

While vocalization and chorusing behavior has been intensively studied in frogs and birds, little has been done with fishes. This paper presents patterns of sound production in damselfish, toadfish, and spotted seatrout on seasonal, daily, and subdaily time scales. Chorus behavior ranges from highly coordinated behavior between neighboring toadfish to uncoordinated behavior in spotted seatrout. Differences in coordination of sound production (i.e., the degree of overlap in calls) can be related to differences in territoriality and modes of reproduction. Toadfish and damselfish are territorial fishes in which males guard benthic eggs laid in nests. Sciaenids (croakers and drums) spawn planktonic eggs, and form temporary aggregations of calling males.
Humpback whale song: A new review
Authors: Frankel Adam S.
Published: October 2013

The humpback whale song has been described and investigated since the early 1970s. Much has been learned about the humpback whale social structure, but the understanding of the song and its function remains elusive. The hierarchical nature of the song structure was described early on: Songs can be sung for a long period, apparently by males, and primarily during the mating season. However, singers also become physically competitive, suggesting alternative mating strategies. There are a number of unique structural features of song. Its structure evolves over time and combination. The nature of song evolution strongly implies cultural transmission. Song structure appears to be shared within an entire population, even though there appears to be little interchange of individuals between sub populations. Despite over thirty years of inquiry there are still numerous unanswered questions: Why is the song structure so complex? Is song a sexual advertisement, an acoustic space mediation mechanism, or both? How do females choose mates, or do they? What drives song evolution, and why is there so much variation in the rate of change? Are there nonreproductive functions of song? What prompts a male to begin or end singing? Our current understanding and the outstanding questions yet to be answered will be reviewed.
Listening to Nature’s orchestra with peculiar ears
Authors: Yager David D.
Published: October 2013

Insects use hearing for the crucial tasks of communicating with conspecifics and avoiding predators. Although all are based on the same acoustic principles, the diversity of insect ears is staggering and instructive. For instance, a South African grasshopper demonstrates that hearing conspecific calls is possible over distances 1 km with ears that do not have tympana. Actually, these creatures have six pairs of ears that play different roles in behavior. In numerical contrast, praying mantises have just a single ear in the ventral midline. The ear is very effective at detecting ultrasonic bat cries. However, the bioacoustics of sound transduction by two tympana facing each other in a deep, narrow slit is a puzzle. Tachinid flies demonstrate that directional hearing at 5 kHz is possible with a pair of ears fused together to give a total size of 1 mm. The ears are under the fly’s chin. Hawk moths have their ears built into their mouthparts and the tympanum is more like a hollow ball than the usual membrane. As an apt last example, cicada ears are actually part of the orchestra: their tympana function both in sound reception and sound production.
The vocal monotony of monogamy
Authors: Thomas Jeanette
Published: October 2013

There are four phocids in waters around Antarctica: Weddell, leopard, crabeater, and Ross seals. These four species provide a unique opportunity to examine underwater vocal behavior in species sharing the same ecosystem. Some species live in pack ice, others in factice, but all are restricted to the Antarctic or sub-Antarctic islands. All breed and produce vocalizations under water. Social systems range from polygyny in large breeding colonies, to serial monogamy, to solitary species. The type of mating system influences the number of underwater vocalizations in the repertoire, with monogamous seals producing only a single call, polygynous species producing up to 35 calls, and solitary species an intermediate number of about 10 calls. Breeding occurs during the austral spring and each species carves-out an acoustic niche for communicating, with species using different frequency ranges, temporal patterns, and amplitude changes to convey their species-specific calls and presumably reduce acoustic competition. Some species exhibit geographic variations in their vocalizations around the continent, which may reflect discrete breeding populations. Some seals become silent during a vulnerable time of predation by killer whales, perhaps to avoid detection. Overall, vocalizations of these seals exhibit adaptive characteristics that reflect the co-evolution among species in the same ecosystem.
Measuring ambient ocean bubble fields using a multibeam sonar
Authors: Adelman Steve , Bradley David L. , Culver R. Lee , Weber Thomas C.
Published: October 2013

For two weeks in July 2002 off the coast of San Diego, a 240 kHz SeaBat 8101 Multibeam Echosounder System was used to measure the backscatter from ambient bubble fields in the near surface layer. The sonar system was mounted approximately 12.5 meters below the surface on the hydraulic orientation unit of the research platform FLIP and was oriented so that its fan of 101 1.5 degree beams were looking at the surface at an angle of 45 degrees from the vertical. Data collection was part of a joint experiment involving the Applied Research Laboratory (ARL)/The Pennsylvania State University (PSU) and the Marine Physical Laboratory (MPL)/Scripps Institute of Oceanography (SIO). Although sea conditions were benign for most of the test period, wind wave activity near the end provided a number of opportunities to observe near surface bubble entrainment. The sonar system proved to be an effective tool for the observation of the lifetime, spatial structure and dimensions of the ambient bubble fields. [Work supported by ONR under Award No. N00014-02-1-0156.]
Internal wave observations and transmission losses in the Santa Barbara Channel
Authors: Dunne Jeff , Diachok Orest , Wales Stephen
Published: October 2013

Measurements from three vertical line arrays of temperature probes, deployed in a triangular configuration in the Santa Barbara Channel in August 2002, permitted determination of speed and direction of tidally generated internal solitary wave events (ISWEs). Two arrays were deployed 2 km apart along a 60-m isobath, with the third normal to the isobath. Sound propagation measurements were also conducted along the isobath. Highly correlated ISWEs were evident on all three arrays every 12 h. Measurements of time delays suggest that these waves emanated from a single site between two of the Channel Islands. Because the ISWE propagation direction was nearly normal to the acoustic propagation direction, acoustic mode coupling due to ISWEs is expected to be minimal. Time-series temperature measurements reveal that average near-surface sound speeds were systematically different when ISWEs were present or absent, and changed abruptly during transitions. Numerical simulations with a normal mode propagation code (C−SNAP) indicate that frequency-dependent differences in transmission loss on near-bottom hydrophones may be as large as 7 dB in narrow frequency bands (5%–10%) between 0.5 and 2 kHz when an ISWE is present versus when it is absent. [Work supported by ONR.]
Whispering-gallery-mode trapping of sound in shallow water between an up-slope region and internal wave solitons
Authors: Pierce Allan D. , Lynch James F.
Published: October 2013

Double-trapping of sound occurs in shallow water when the ocean has a sloping bottom and when a packet of high amplitude internal wave solitons is propagating either up-slope or down-slope. The phase velocity of an adiabatic mode increases in the up-slope direction and also as one approaches the front of the soliton packet, so the mode’s horizontal rays can be trapped for propagation that is nominally cross-slope. Because the variation of the horizontal phase velocity is considerably slower in the up-slope direction than it is in the vicinity of the soliton front, an analogy exists with the whispering-gallery effect (found near concave surfaces in architectural spaces). The equivalent radius of curvature of the ‘‘reflecting surface’’ is found in accord with the earth-flattening approximation to equal the phase velocity divided by its derivative with respect to the up-slope distance. Quantitative substantiation is given for models of sound and solitons in a realistic ocean (two constant sound speed layers separated by a thermocline). Double-trapped propagation has some attenuation because of energy leakage out through the width of the soliton packet.
High intensity focused ultrasound (HIFU) for treatment of T1/T2 prostate cancer
Authors: Sanghvi N. , Gardner T. , Koch M.
Published: October 2013

This FDA approved phase I/II clinical trial is to evaluate the safety and efficacy of the Sonablate device (Focus Surgery, Inc.) for the treatment of organ confined prostate cancer. 20 patients with biopsy proven prostate cancer, Gleason ≤7 and PSA ≤10 were treated under general anesthesia. Outcome data included serum PSA collected at day 3, 14, 30, 90, 180, PSA nadir (mean/median), and biopsy results at 6 months. Quality of life was assessed using the International Prostate Symptom Score, International Impotence and Erectile Function score, and the SF-36 health survey. The mean patient age is 62.0, Gleason score of 6.18, PSA of 5.2, and prostate size 26.0 gm. Mean PSA results were 5.62, 44, 20, 1.68, 0.87, and 0.44 ng/ml at screening, 48–72 hours, 14 days, 30 days, 90 days and 180 days, respectively. There was one patient (9%) with a positive TRUS biopsy at 6 months, which resulted in a retreatment. There were no rectal injuries. Average pre-treatment IPSS, IIEF, and SF-36 scores were 9.55, 16.1, and 103.5. At the 30 day follow-up, they were 18.3, 3, and 97.4, respectively. HIFU is a minimally invasive modality that achieves complete prostatic ablation and is efficacious in the treatment of low-stage prostate cancer.
Determination of dimensionless attenuation coefficient in shaped resonators
Authors: Daniels Christopher C. , Finkbeiner Joshua R. , Steinetz Bruce M. , Li Xiaofan , Raman Ganesh
Published: October 2013

The value of the dimensionless attenuation coefficient is an important factor when numerically predicting high-amplitude acoustic waves in shaped resonators. Both the magnitude of the pressure waveform and the quality factor rely heavily on this dimensionless parameter. Previous authors have stated the values used, but have not completely explained their methods of determination. This work fully describes the methodology used to establish this important parameter. Over a range of frequencies encompassing the fundamental resonance, the pressure waves were experimentally measured at each end of the shaped resonators. At the corresponding dimensionless acceleration, the numerical code modeled the acoustic waveforms generated in the resonator using various dimensionless attenuation coefficients. The dimensionless attenuation coefficient that most closely matched the pressure amplitudes and quality factors of the experimental and numerical results was determined and will be used in subsequent studies.
Numerical simulation of streaming in high amplitude standing wave resonators
Authors: Boluriaan Said , Morris Philip
Published: October 2013

Classical theories of acoustic streaming in a long standing wave resonator predict a streaming velocity with a parabolic profile across the resonator. Recently, an analysis by Menguy and Gilbert [Acustica 86, 249–259 (2000)] has shown that the parabolic streaming velocity profile is obtained only for low acoustic pressure amplitudes. At a higher amplitude, the streaming velocity deviates from a parabolic distribution. In a more recent experiment, Thompson and Atchley [J. Acoust. Soc. Am. 111, 2418 (2002)] have also observed streaming velocities that are different from those predicted by the classical theory when a high amplitude standing wave is used. Furthermore, there are indications that the type of the boundary condition (adiabatic or isothermal, for instance) may affect the mean velocity. In the present research, numerical simulations are performed for a high amplitude standing wave in a resonator. A time-accurate, high-order, finite difference approach on a clustered rectangular grid structure is used and the full Navier–Stokes equations are solved. Results are presented for a wide range of operating parameters and are compared with both the Menguy and Gilbert analysis and the experiments. Moreover, the time evolution of the streaming velocity is investigated.
Insensitivity to large differences in interaural correlation
Authors: Culling John F.
Published: October 2013

Sensitivity to differences in interaural correlation was measured using an adaptive threshold technique. The 2-down/1-up adaptive track began at the opposite correlation value from the standard (e.g., starting at 1 and converging on −1). Each 3I-FC trial was followed by correct/incorrect feedback. Steps in the adaptive track were initially linear and switched to logarithmic as the track passed zero interaural correlation. First, four listeners were trained to asymptote using a band of noise (462–540 Hz). The listeners were then trained under identical circumstances, but with remote flanking bands (0–330 and 719–3000 Hz) of interaurally correlated, synchronously gated noise, equal in spectrum level to the target band. The listeners were also occasionally given an adaptive track beginning at zero interaural correlation. With no flanking bands, three listeners experienced difficulty learning to adapt from 1 to −1, frequently recording threshold differences in correlation close to 2. Little difficulty was experienced when adapting from −1 to 1 and none when adapting from zero in either direction. When remote flanking bands were added, all listeners experienced greater difficulty. Only one listener learned to converge on −1. The salience of cues used by the listeners seemed to decrease when comparing high positive and negative correlations.
Binaural versus better-ear listening
Authors: Scarpaci Jacob W. , Durlach N. I. , Colburn H. Steven
Published: October 2013

Advantages of binaural over monaural hearing in noisy environments are reduced when the monaural stimulation is derived from the monaural signal with the better signal-to-noise ratio (better-ear listening). In the reported experiments, conducted in a soundproof room with two speakers and a custom-designed, noise-cancellation headset, speech intelligibility in the presence of interference was measured for both binaural and better-ear configurations. The headset, which incorporated two microphones (located at the two ears) and two insert earphones, was used to present binaural stimulation or better-ear (better-microphone) monaural stimulation. Although the results varied significantly with the locations of the target and interference sources, the advantage of binaural listening over better-ear listening was no more than a few dB. In addition to reporting the data obtained in these experiments, relations to previous work on better-ear listening and CROS hearing aids, as well as to current work on cochlear implants, are discussed. [Work supported by NIDCD (00100).]
Upward spread of informational masking in normal-hearing and hearing-impaired listeners
Authors: Alexander Joshua M. , Lutfi Robert A.
Published: October 2013

Thresholds for pure-tone signals of 0.8, 2.0, and 5.0 kHz were measured in the presence of a simultaneous multitone masker in 15 normal-hearing and 8 hearing-impaired listeners. The masker consisted of fixed-frequency tones ranging from 522–8346 Hz at 1/3-octave intervals, excluding the 2/3-octave interval on either side of the signal. Masker uncertainty was manipulated by independently and randomly playing individual masker tones with probability p=0.5 or p=1.0 on each trial. Informational masking (IM) was estimated by the threshold difference (p=0.5 minus p=1.0). Decision weights were estimated from correlations of the listener’s response with the occurrence of the signal and individual masker components on each trial. IM was greater for normal-hearing listeners than for hearing-impaired listeners, and most listeners had at least 10 dB of IM for one of the signal frequencies. For both groups, IM increased as the number of masker components below the signal frequency increased. Decision weights were also similar for both groups—masker frequencies below the signal were weighted more than those above. Implications are that normal-hearing and hearing-impaired individuals do not weight information differently in these masking conditions and that factors associated with listening may be partially responsible for the greater effectiveness of low-frequency maskers. [Work supported by NIDCD.]
Criteria placement in staircase procedures
Authors: Richards Virginia M. , Huang Rong
Published: October 2013

Data from several masking studies are evaluated to determine whether observers alter their decision criteria as signal levels increase and decrease according to an adaptive staircase algorithm. In a Yes/No procedure, a 1000-Hz signal tone is added to one of twelve maskers. Each masker is composed of six equal-amplitude tones with frequencies drawn at random from a 200–5000 Hz range. In two conditions, the maskers are either fixed across several sessions or randomly drawn prior to each trail. Data from at least 15 staircases are combined, and for each signal level the overall hit and false alarm rates are determined. Regardless of condition, fixed or random, observers tend to adopt a single criterion across all signal levels. If it is assumed that in the random condition a single criterion is used across all trials, the location of the mean of the no-signal distributions relative to the criterion can be estimated. For the current data, the pattern of no-signal distributions is not obviously related to masker properties. [Work supported by NIH.]
Comparison of acceptance of background noise and speech reception threshold in quantifying the hearing aid directivity benefit
Authors: Freyaldenhoven Melinda C. , Nabelek Anna K. , Burchfield Samuel B.
Published: October 2013

Hearing aid directivity benefit was compared as improvement in acceptance of background noise and speech reception threshold (SRT). Forty adult subjects were tested wearing binaural hearing aids in omnidirectional and directional listening conditions. Acceptance of background noise was determined by having subjects select their most comfortable listening level (MCL) for a story delivered from a loudspeaker (0). Next, speech babble was added (180) and the subjects selected the maximum background noise level (BNL) which was acceptable while listening to and following the story. The MCL minus the BNL yielded the acceptable noise level (ANL), all in dB. The difference between the ANL for the omni-directional and directional conditions is the directivity benefit. The SRT was determined by delivering spondaic words (0) at the subjects MCL. Next, speech babble was delivered (180) and adjusted until the subject could repeat 50% of the spondees. The difference between the SRT for the omni-directional and directional conditions is the directivity benefit. Mean directional benefit, ANL=3.50 dB and SRT=3.60 dB, were not significantly different. The individual ANLs and SRTs were significantly correlated (r=−0.36, p=0.002). The ANL procedure appears to be a viable tool for quantifying hearing aid directivity benefit. [Work supported by NIDCD (NIH) 3 RO1 DC 05018-01S1.]
Effects of relative frequency, absolute frequency, and phase on fundamental frequency discrimination: Data and an autocorrelation model
Authors: Bernstein Joshua , Oxenham Andrew
Published: October 2013

Fundamental frequency (F0) difference limens (DLs) were measured versus F0 for sine- and random-phase harmonic complexes bandpass-filtered into low- or high-frequency regions, with 3-dB passbands of 2.5–3.5 and 5–7 kHz, respectively. In all cases, F0 DLs decreased dramatically with increasing F0 as approximately the tenth harmonic appeared in the passband. Generally, F0 DLs were similar in both frequency regions for complexes with similar harmonic numbers and phase relationships. However, F0 DLs were larger in the high-frequency than the low-frequency region for random-phase complexes containing only harmonics above the tenth, suggesting a possible role for additional fine-structure information in the low-frequency region. The dependence of F0 discrimination on relative frequency presents a significant challenge to autocorrelation (AC) models of pitch perception, in which predictions generally depend more on absolute frequency and phase locking. To represent this relative frequency effect, a ‘‘lag window’’ modification to the Meddis and O’Mard [J. Acoust. Soc. Am. 102, 1811–1820 (1997)] AC model was introduced, restricting each channel’s AC representation to a limited range of lags relative to the center frequency (CF). Thus in each channel, the AC model responds best to F0’s whose dominant harmonics fall near the CF. [Work supported by NIH Grant Nos. 5T32-DC-00038 and R01-DC-05216.]