bluuebunny/crossref_metadata_2025 huggingface dataset:
The estimated ocean detector (EOD) for Gaussian signal and noise
Authors: Ballard Jeffrey A. , Jemmott Colin W. , Sibul Leon H. , Culver R. Lee , Camin H. John , Bradley David L.
Published: October 2013

Our overall goal is to develop a method for incorporating knowledge of the environment, and in particular, environmental variability, into the signal processor. This talk begins with the assumption that all available information about the environment has been used to compute the probability density functions (pdfs) of relevant received signal parameters (e.g., amplitude or time spread). For the exponential class of pdfs that arises from applying the maximum entropy method to random signal parameters, the maximum likelihood detectors (MLD) can be implemented as an estimator-correlator [Schwartz, ‘‘The estimator-correlation for discrete-time problems,’’ IEEE Trans. on Information Theory. 23, 93–100 (1977)]. The MLD detector correlates received data with the conditional mean estimate of the signal; hence we have named it the estimated ocean detector (EOD). Here, we present the general structure of the EOD and explore EOD performance for Gaussian signals and noise, which are members of the exponential class. The resulting implementation produces a detection statistic that is the weighted sum of an energy detector and a correlation receiver, with the weights calculated from the variances of the noise and signal. EOD performance bounds are calculated using completely known and completely unknown oceans. [Work supported by The Undersea Signal Processing Program, Office of Naval Research.]
A method to predict active sonar detection range in uncertain shallow water environments
Authors: Cable Peter G.
Published: October 2013

Knowledge of maximum detection range is important for the appropriate operation of search sonar. For example, effective spacing of multistatic sonar sources and receivers will be influenced by good estimates of achievable detection range. But predicting detection range for low-frequency active sonar in shallow water can be problematic in the face of inadequate environmental characterization. Thus, incomplete knowledge of bottom sediment geoacoustics and bottom scattering strength, and absence of a good understanding of bottom reverberation mechanisms, will greatly hamper the accurate prediction of dependable detection ranges. Given a bistatic sonar configuration in shallow water, a method is proposed and described that exploits the observed transition time from reverberation to noise-limited conditions to simply and robustly predict maximum detection range for specified target strength. Modeling and analysis suggest that estimates of maximum detection range within 25% accuracy can be readily achieved.
Spatial diversity in passive time reversal communications
Authors: Song H. C. , Hodgkiss W. S. , Kuperman W. A. , Akal T. , Stevenson M.
Published: October 2013

A time reversal mirror exploits spatial diversity to achieve spatial and temporal focusing, a useful property for communications in an environment with significant multipath. This paper presents the impact of spatial diversity on passive time reversal communications between a single probe source and a vertical receive array using at-sea experimental data, while the probe source is either fixed or moving at about 4 knots. The performances of two different approaches are compared: (1) time reversal alone and (2) time reversal combined with adaptive channel equalization. In the presence of source motion, the motion-induced Doppler shift is coarsely estimated using a decision-feedback phase-locked loop with a training sequence and then the received time series is resampled prior to the demodulation process. The time-varying channel responses due to source motion require an adaptive channel equalizer such that time reversal combined with the equalizer outperforms time reversal alone by up to 13 dB as compared to 5 dB for a fixed source case. The experimental results around 3 kHz with a 1-kHz bandwidth illustrate that even two or three receivers (i.e., 2- or 4-m aperture) can provide resonable performance at 4.2- and 10-km ranges in a 118-m deep water.
Surface reflection caustics and their impact on communications in the littoral zone
Authors: Deane Grant
Published: October 2013

Gravity waves with wavelengths longer than a Fresnel zone create cusps and caustics in the surface-reflected acoustic field. The properties of these coherent focal regions have been measured in the surf zone and the 20-m-deep littoral waters off Martha’s Vineyard. The time-dependent scattering function shows features consistent with a theoretical analysis of the focal region micro-path structure. The rapid amplitude, phase, and Doppler shifts associated with individual micro-paths present challenges to the reliable operation of phase-coherent underwater communications systems that must implicitly or explicitly track the fluctuations in the impulse response. Data from the experiments will be presented and the implications for underwater communications systems will be discussed. [This work has been undertaken in close collaboration with Dr. James Preisig at the Woods Hole Oceanographic Institution and Dr. Chris Tindle at the Auckland University Physics Department, New Zealand, and supported by the Office of Naval Research.]
The effect of medium variability on acoustic variability: Internal waves and thermohaline intrusions (spice)
Authors: Lyons Joy E. , Bradley David L. , Culver R. Lee , Becker Kyle M.
Published: October 2013

In July 2002, an experiment was conducted off the coast of southern California in which the two-dimensional temperature and salinity field were measured directly using a towed conductivity, temperature, and depth chain. The spatial scales are approximately 3500 m long by 80 m deep, with a horizontal resolution of 1–2 m. The resulting sound-speed field has been decomposed into fields of internal waves and density-compensated, thermohaline intrusions. The medium variability in these two fields covers many spatial scales. High-frequency acoustic propagation (1–5 kHz) through the derived fields, as well as through the original field, was computed using the PE-based model RAM and the ray-trace model RAY. Using the metric of scintillation index, the contributions of internal waves and thermohaline intrusions to the acoustic variability are examined, and their relative contributions to the total acoustic variability quantified.
Equine acoustics: Further analysis of a whinny—The expressive component
Authors: Browning David G. , Scheifele Peter M.
Published: October 2013

A horse’s whinny appears to be a very interesting vocalization. Initial acoustic analysis suggested two principal components, one ‘‘emotional’’ and the other ‘‘expressive.’’ The first seems to follow Morton’s criterion: increasing frequency with emotional state. The second component, since many suggest that a whinny is not a threatening gesture, has the potential for a number of specific expressions for such situations as ‘‘calling’’ or ‘‘greeting.’’ This paper describes the present indications as the data base slowly increases.
Discovery of Sound in the Sea website: An educational resource
Authors: Vigness Raposa Kathleen J. , Scowcroft Gail , Johnen Jill , Knowlton Chris , Worcester Peter F.
Published: October 2013

The scientific community and the public have become increasingly aware of, and concerned about, underwater sound. There is increasing interest in learning about sources and uses of sound, and potential effects of sound on the marine environment. The Discovery of Sound in the Sea website (http://www.dosits.org) provides scientific information for the general public and K–16 educators and students. It also includes advanced level content appropriate for high school physics or undergraduate classes. The website has three major sections, (1) Science of Sound in the Sea, (2) People and Sound in the Sea, and (3) Animals and Sound in the Sea, introducing the physical science of underwater sound and how people and animals use sound to accomplish various tasks. The Animals and Sound section also summarizes the current state of knowledge of the effects of underwater sound on marine mammals and fishes. Three galleries contain a collection of underwater sounds (Audio Gallery), video interviews with researchers (Scientist Gallery), and descriptions of acoustic equipment (Technology Gallery). Additions to the website are ongoing. Scientists with recordings and/or equipment that have not been included are encouraged to contact the authors. A limited number of free CDs of the website will be available.
The roles of density, geometry, and short-range positional order in low-frequency acoustic scattering from fish schools
Authors: Hahn Thomas R. , Elfouhaily Tanos
Published: October 2013

Fish can be efficient scatterers of low-frequency underwater sound. This results from the large response of their swim bladders to incoming acoustic waves at frequencies close to their natural resonance frequencies. For large and densely packed fish schools the scattering returns deviate significantly from what could be expected by adding the individual fish returns. These deviations are caused by multiple scattering between the individual fish in the school and concern the target strength as well as the spectral and directional characteristics of the scattering cross sections. Acoustically, a fish school can be viewed as a single object with acoustic bulk parameters determined from the properties of the individual fish and their positional arrangement in the school. This effective medium approach incorporates the acoustic coupling of all fish due to multiple scattering and works for a wide range of fish sizes, -numbers, and -densities. In this study, the effective medium approach as well as numerical computations from first physical principles are employed to investigate the coherent and diffusive low-frequency scattering cross sections of large and dense fish schools as a function of fish density, school geometry, and positional order among the individual fish. Inversions for these parameters are explored.
Echogenic targeted liposomes for transfection and drug delivery
Authors: McPherson David D.
Published: October 2013

We have developed targeted, echogenic immunoliposomes. These agents are lipid based, can be targeted to cells, and have encapsulated air bubbles that render them echogenic, and the air bubbles can also be used as cavitation agents. They have the ability to encapsulate drugs and genes. We have developed stable formulations and optimized attachment of antibodies and peptides for targeted molecular imaging using ultrasound. We are determining the pharmacokinetics of drug and gene entrapment and the ultrasonic destruction threshold for therapeutic delivery. With the enclosed cavitation agent, therapeutic ultrasound (sonoporation) potentiates cellular drug and gene delivery. This presentation will focus on optimizing the liposomes for stability, targeting, drug entrapment and release, destruction threshold, and the additive sonoporation effect of the encapsulated cavitation nucleii. Tissue plasminogen activator and papaverine are prototype drugs and beta-galactosidase is the prototype gene for encapsulation. The objective of this work is to use modifications of our echogenic immunoliposomes to better entrap and release drugs and genes, while utilizing the enclosed cavitation nucleii, which allows ultrasound to not only release the drug/gene, but also improve its delivery.
In vitro and in vivo high-frequency ultrasound response of microbubbles
Authors: Aristizábal Orlando , Turnbull Daniel H. , Ketterling Jeffrey A.
Published: October 2013

Recently, there has been a growing interest in utilizing contrast agents with high-frequency ultrasound (HFU > 20 MHz). As a first step to using contrast agents in vivo with HFU, the acoustic response of several agents was examined using a 40-MHz ultrasound biomicroscope (UBM, Vevo 770, VisualSonics). Optison, Definity, and near-micron and submicron agents from Point Biomedical were investigated. A small volume of the agents was injected into a petri dish of saline solution, and radio-frequency (rf) backscatter data from the UBM were digitized with a digital oscilloscope. Agents were also injected into the cardiovascular system of mouse embryos and rf data were acquired in vivo. The echo signals from individual bubbles were windowed in the rf data and the spectra were calculated. The resulting spectra revealed an increasing harmonic content for each of the agents as the acoustic drive amplitude and number of excitation wavelengths increased. Harmonic generation appeared to be due mainly to nonlinear propagation in the water bath and not from a nonlinear response of the contrast agent because reflected spectra without contrast agent showed similar harmonics. Using a modified parameter imaging method, fundamental (40 MHz) and first-harmonic (80 MHz) images were generated.
On the evolution of controllers for sound spatialization
Authors: Braasch Jonas
Published: October 2013

Dynamic changes in spatial sound attributes have played a role in classical Western music for a long time. It is known that choreographic movements of opera singers were sometimes made for acoustic considerations. Probably the first mechanical spatial sound controller is the so-called wind swell that is found in pipe organs. Already in 1712, Renatus Harris mentions how swelling enables the player to project the sound of the pipes ad libitum to nearby or further distances. With the invention of electroacoustic music, a number of electromechanical devices were developed to control spatial aspects of sound (primarily positioning sound sources in 3-D space). Typical examples are Stockhausen’s rotational table (developed in the 1950s) and Manfred Krause’s sound mill (1960). In this presentation, the evolutionary steps in the design of spatial sound controllers will be outlined—beginning with early, purely mechanical devices up to recent approaches including the author’s participation in the development of a gestural controllable sound system based on virtual microphone control (ViMiC).
Idiomatic guitar synthesis
Authors: Costalonga Leandro L. , Miranda Eduardo R.
Published: October 2013

The aim of this research is to add intelligence to the interface between systems for computer-aided composition and synthesizers. In this paper we introduce a system that is able to play guitar music on a synthesized guitar idiomatically. There are a great number of sound synthesis techniques and computer-aided composition systems available. However, there is a general lack of intelligent interfacing between these two types of systems. For example, when one auditions the different parts of an orchestral piece, the software treats these materials identically; that is, the violin part is not played violinistically or the clarinet part clarinetistically. Musicians tend to blame the synthesizers for such poor performance quality, but if the synthesizer was controlled idiomatically the sound synthesis technique itself would be just one of the design aspects to be considered in such systems, and not the single one. Our idiomatic guitar player system includes knowledge about the biophysical constraints of the performer, the performance characteristics associated with different musical styles, and the performance styles of different individuals. [Research sponsored by CAPES Ministry of Education of Brazil.]
Better model and decoding methods for automatic speech recognition
Authors: O’Shaughnessy Douglas D. , Nagarajan Li T.
Published: October 2013

Different ways to improve the accuracy and performance of automatic speech recognition (ASR) systems are examined. Earlier research in the INRS group concentrated on improvements in adaptation techniques, to try to reduce the mismatch between system training and operating conditions. More recently, a concentration was made on improvements to the modeling and decoding methodology of the ASR systems. A two-level syllable model-based decoding approach is proposed here. At the first level, a syllable model-based decoding is performed to segment the utterances into syllable segments, and to identify which syllable group this segment belongs to. Then, at the second level, each segment is rescored using the phoneme model, where the possible phoneme sequences are constrained by the syllables in that syllable group. A new heuristic score is proposed to be added in hidden Markov model (HMM) decoding that indicates the degree of competition among different HMM states. Speech features are obtained from the posterior of this HMM approach and these features are used to further improve recognition results. The state evolution tracks are incorporated as features in an HMM-based recognizer. Experiments were carried out on a phoneme classification task (TIMIT) and these methods were found to show improvements compared to a baseline performance. [Work supported by NSERC-Canada and Prompt-Quebec.]
Speaker identification in hybrid synthesis: Implications for speech perception
Authors: Hertz Susan R. , Spencer Isaac C.
Published: October 2013

As part of an evaluation of hybrid synthesis [Hertz, Proc. IEEE Workshop on Speech Synthesis (2002)], perceptual experiments were conducted that tested the hypothesis that stressed vowels are the primary cues to speaker identification. Hybrid sentences were constructed for eight voices, including child and adult and male and female, in which stressed vowels were taken from a single human speaker, but other segments were replaced by surrogates from different sources. Some surrogates were natural speech segments; others were formant synthesized. Some matched the age or gender of the stressed vowel speaker; others did not. After being trained on six human target voices, listeners were asked to identify the hybrid stimuli, and also fully synthetic and natural stimuli (for target and nontarget voices), in terms of age, gender, and whether and how much they matched a target voice. For all categories, hybrid stimuli, in contrast to synthetic ones, were identified as accurately as natural speech, both by listeners familiar with a target voice (e.g., family members) and those unfamiliar. The experiment demonstrated how little attention is paid to consonants and reduced vowels in determining speaker identity, and supported our hybrid approach to modeling voices. [Work supported by NIH Grant 1 R43 DC006761-01.]
Garden-path phenomena in spoken word recognition: Gradient sensitivity to continuous acoustic detail facilitates ambiguity resolution
Authors: McMurray Bob , Tanenhaus Michael K. , Aslin Richard N.
Published: October 2013

Studies have demonstrated that lexical activation is gradiently sensitive to continuous acoustic detail [McMurray et al., ‘‘Gradient effects of within-catagory phonetic variation on lexical access,’’ Cognition 86, B33–B42 (2002)]. This study investigates the consequences of this for online recognition, hypothesizing that such processes help maintain lexical alternatives and reactivate them if early interpretations are disfavored by subsequent input. Stimuli were pairs like barricade/parakeet, where, if the initial segment was misperceived, disambiguation would occur quite late. The effect of VOT on recognition was assessed for tokens favoring the competitor (barakeet with VOTs between 15 and 0). A categorical system would categorize these as equally [b]; garden path to barricade; and show difficulty reactivating parakeet after /eet/. A gradient system would activate parakeet more for VOTs near the boundary, and recover from the garden path faster. Subjects heard ten 8-step continua of this form and selected the target from screens containing the target (parakeet), competitor (barricade), and unrelated objects, while eye movements were recorded. Fixations revealed a gradient pattern of recovery time to switch from the competitor to the target was linearly related to VOT. Subsequent experiments verified that this was not due to stimulus range, nor to the visual presence of the competitor. Thus, lexical activation is sensitive to continuous detail, and this facilitates ambiguity resolution.
The effect of tonal information and word frequency on spoken word processing
Authors: Lin Yao-ju , Fon Janice
Published: October 2013

This paper aims to examine the role of tonal information and word frequency in processing spoken Mandarin lexicon. Experiment 1 uses a lexical decision paradigm in which subjects are to hear high- and low-frequency bisyllabic word pairs whose segmental makeups are similar (e.g., [high frequency] jing4-zheng1 competition vs. [low frequency] jin4-sheng1 promotion). The F0 information of the stimuli are either uncontaminated, transformed for the second syllable, or transformed for both syllables. Experiment 2 uses a shadowing task with the same set of stimuli in which subjects are asked to repeat the words as quickly as possible. Preliminary results showed that tonal information is essential for lexical retrieval, especially for low-frequency words. Based on the TRACE model, it is also expected that subjects are more likely to substitute similar-sounding words of higher frequency for low-frequency words whose F0 information is manipulated.
Statistical and change-detection analyses using quantitative side-scan-sonar data
Authors: Caruthers Jerald W.
Published: October 2013

This paper discusses recent basic, high-frequency, bottom-backscattering research conducted in conjunction with sediment-classification projects and the ONR bottom scattering research projects, KauaiEx and SAX04. This work has a bearing on statistical analyses and bottom change detection relevant to the detection of objects on or near the bottom in shallow water. The research discussed here includes the analyses of data from three surveys made between 2002 and 2004. The primary contributions of this work are based on the use of probability density functions (PDFs) of the backscatter signals to specify the various regimes of bottom sediments and to detect spatial changes in these regimes based on chi-square and other tests applied to these PDFs. A simple, quantitative test for non-Rayleighness of a PDF was also applied. [This work was supported by the ONR.]
Characteristics of visually-induced auditory spatial adaptation
Authors: Lin I-Fan , Kopčo Norbert , Groh Jennifer M. , Shinn-Cunningham Barbara G.
Published: October 2013

In humans, visual and auditory spatial information arise in different reference frames, with auditory information being head-centered based on interaural cues, whereas visual information derives from the retinal activation, an eye-centered signal. This study investigated whether visually-guided recalibration of auditory space occurs in a head-centered, eye-centered or a hybrid (combination of both) reference frame. Subjects made saccades to combined auditory-visual targets. The visual component of the target was displaced laterally by 5°. Interleaved auditory-only trials served to evaluate the effect of the mismatched visual stimulus on auditory space. To dissociate head- from eye-centered reference frames, the initial fixation position of the eyes was varied. The results reflected contributions of both coordinate frames. First, the magnitude of the induced shift was affected by the eye-centered location of the targets, but occurred at a consistent location in head-centered space. Second, when subjects were trained using one fixation position and tested using a different fixation position, the magnitude of the induced shift was reduced, but the target locations that showed the greatest shift did not move. The hybrid nature of these effects is reminiscent of recent demonstrations of eye position modulation in the auditory pathway of non-human primates. [Work supported by NIH]
Impact of a shelfbreak front on array processing in shallow water
Authors: Lin Ying-Tsong , Newhall Arthur E. , Lynch James F.
Published: October 2013

In a coastal ocean shelfbreak front region, underwater sound can horizontally refract in the offshore direction due to the sloping bottom and reflect/refract back shoreward due to the ocean front. To study this interesting phenomenon, an analytic solution for an ideal wedge with a frontal interface was introduced in our previous paper [Lin et al., J. Acoust. Soc. Am. 120, 3182 (2006)]. This analytic solution suggests that the sound will also tend to propagate along the front, and that so-called ‘‘whispering gallery’’ modes can be observed. In this paper, the consequence of this whispering gallery effect on array processing is discussed. Specifically, the influence of an ideal ocean front on the array gains is studied. Since the sound reflecting from the ocean front forms highly correlated beams, the array gain of a horizontal hydrophone array will be increased. In addition, the application of modal beamforming techniques to resolve the whispering gallery modes propagating along the front is demonstrated. Our research goal for this study is to pursue practical systems to locate an inshore, long-distance sound source and also to monitor the changes of ocean fronts.
Acoustically-guided vocal tract modifications for singing
Authors: Story Brad
Published: October 2013

The sound quality of a specific vowel can be dramatically altered by subtle modifications of the vocal tract shape. These modifications create changes in the pattern of formant frequencies. For example, the well-known singing formant, which is a clustering of resonance frequencies, is typically the result of constricting the epilaryngeal space or expanding the lower pharyngeal space to create a large cross-sectional area discontinuity between them. Other modifications such as lip protrusion/spreading or larynx lowering/raising will also impose changes on the formant frequency pattern that may be desirable for singing or speech production. This presentation will focus on the acoustic sensitivity of the resonance frequencies to subtle perturbations of specific vowel configurations. Using calculated sensitivity functions, it will be shown how specific regions along the vocal tract can be constricted or expanded to perturb one or more of the formant frequencies. In effect, this technique provides a means of ‘‘tuning’’ the vocal tract shape to produce a desired frequency response. [Work supported by NIH R01-DC04789.]
Spatial generalization in short-term perceptual adaptation to novel auditory spaces
Authors: Lin I-Fan , Streeter Timothy , Shinn-Cunningham Barbara , Durlach Nat , Delhorne Lorraine
Published: October 2013

Previous work shows that humans can rapidly adapt to novel mappings between auditory spatial cues and exocentric location and localize accurately with the novel mapping. Here, experiments using (1) a rotation and (2) a linear magnification of auditory space examined generalization of spatial adaptation to untrained or neglected regions of space. Individual head-related transfer functions (HRTFs) were used to simulate different source locations using headphones. Each experimental session was broken into three blocks: initial normal cues (measuring baseline performance), altered cues (showing adaptation), and final normal cues (measuring an adaptation aftereffect). In the altered cues trials, a source at X degrees was simulated using HRTFs that normally correspond to a source at (1) X+30 deg (rotation) or (2) 2X deg (linear magnification). After obtaining subjects’ localization responses to the sound stimulus, feedback was given using a light-emitting diode located at the correct position (X deg). Results of these experiments show the extent to which training subjects to adjust their localization responses in one region of space affects how they localize sources in adjacent regions, and provide a measure of the spatial kernel that drives spatial auditory adaptation.
Passive in vivo elastography from skeletal muscle noise
Authors: Sabra Karim G. , Conti Stephane , Roux Philippe , Kuperman W. A.
Published: October 2013

Measuring the in vivo elastic properties of muscles (e.g., stiffness) provides a means for diagnosing and monitoring muscular activity: muscles typically become ‘‘harder’’ during contraction occurring through physiological changes. Standard elastography imaging techniques estimate soft tissue (e.g., skeletal muscle, breast) stiffness using propagating shear waves in the human body generated by an external active source (e.g., indentation techniques, ultrasonic radiation force). We demonstrated a passive in vivo elastography technique without an active external radiation source. This technique instead uses cross-correlations of contracting skeletal muscle noise recorded with skin-mounted sensors. The coherent arrivals emerge from a correlation process that accumulates contributions over time from noise sources whose propagation paths pass through both sensors successively. Each passive sensor becomes a virtual in vivo shear wave source. The results point to a low-cost, noninvasive technique for monitoring biomechanical in vivo muscle properties. The efficacy of the passive elastography technique originates from the high density of cross paths between all sensor pairs potentially achieving the same sensitivity obtained from active elastography methods. The application of this passive elastography technique for constructing biomechanical models of in vivo muscle properties will be discussed.
The Wildcat corpus of native- and foreign-accented English
Authors: Bradlow Ann R. , Baker Rachel E. , Choi Arim , Kim Midam , Van Engen Kristin J.
Published: October 2013

For a wide range of socio-political reasons, many conversations across the globe today are between interlocutors who do not share a mother tongue. As a resource for investigating the nature and broad implication of speech communication in a global context, we are currently developing a large database of speech recordings from native and non-native speakers of English. A key feature of this database is that, in addition to providing recordings of scripted materials, the speakers are recorded in pairs (all possible pairing of native and non-native English speakers) as they work together on a novel, interactive, goal-oriented task. The final corpus will include fully segmented and phonetically aligned digital recordings of both the scripted and unscripted speech samples along with complete orthographic transcriptions. We are currently using a first version of this database to track speaker-listener alignment over the course of a conversation, to compare phonetic features of speech addressed to native versus to non-native speakers, and to assess communication efficiency across various native and non-native speaker pairings (e.g., how long does it take for a team-based task to reach successful completion when one, both, or neither of the team members is a non-native speaker?)
Hearing screening in bottlenose dolphins using single and multiple auditory evoked potentials
Authors: Finneran James J. , Houser Dorian S. , Blasko Dave , Hicks Christie , Hudson Jim , Osborn Mike , Walsh Kevin M.
Published: October 2013

Auditory thresholds were estimated in four bottlenose dolphins (Tursiops truncatus) by measuring auditory evoked responses to single and multiple sinusoidal amplitude modulated tones. Subjects consisted of two males and two females with ages from 4 to 22 years. Testing was conducted in air using a jawphone transducer to couple sound into the subjects lower right jaw. Carrier frequencies ranged from 10 to 160 kHz in one-half octave steps. Amplitude-modulated stimuli were presented individually and as the sum of four, five, and nine tones with unique carrier and modulation frequencies. Evoked potentials were noninvasively recorded using surface electrodes embedded in silicon suction cups. The presence or absence of an evoked response at each modulation frequency was assessed by calculating the magnitude-squared coherence from the frequency spectra of the recorded epochs. All subjects exhibited traditional U-shaped audiograms with upper cutoff frequencies above 113 kHz. The time required for threshold estimates ranged from 30–45 min for single stimuli and 4–8 min for nine simultaneous stimuli. Agreement between thresholds estimated from single stimuli and multiple, simultaneous stimuli was generally good, suggesting that multiple stimuli may be used for quick hearing assessment when time is limited. [Work supported by ONR.]
Spectral profile cues in comodulation masking release
Authors: Buss Emily
Published: October 2013

Previous work on spectral profile discrimination has shown that sensitivity is dependent on position of the signal in the standard complex, with a profile bowl shape demonstrated for components spanning 0.2–5 kHz [Green, Profile Analysis, 1988]. Dynamic spectral cues similar to those in profile analysis are present in comodulation masking release (CMR) stimuli, and the current study examined whether a similar bowl occurs for CMR. Maskers were 11 bands of noise, 15-Hz wide, logarithmically spaced 0.2–5 kHz, and maskers were either random or coherently modulated. The signal was either a pure tone at center frequency of one of these masker bands or the on-signal masker band itself. In the random conditions, thresholds were consistent across signal frequency for both signal types. In the coherent modulation conditions a bowl shape was obtained for the narrowband noise signal, but when the signal was a pure tone thresholds improved as a function of signal frequency and showed little evidence rising again at the highest signal frequencies tested. Data collected with the signal and on-signal masker presented contralateral to the flanking maskers indicate a reduced effect of signal type. Contribution of within- and across-channel cues will be discussed.
High frequency signal amplitude fluctuations in shallow water
Authors: Chotiros Nicholas P. , Isakson Marcia J. , Piper James N. , Zampolli Mario
Published: October 2013

Amplitude fluctuations were measured in a high-frequency (5–50 kHz) experiment over short ranges in 10 meters of water on the north shore of Isola dElba, Italy. The fluctuations, as a function of range and frequency, are compared with estimates using the empirical refractive index wave-number spectrum put forward by Medwin [J. Acoust. Soc. Am. 56, 4 (1974)] for the upper ocean region. The spectrum is governed by the distance from the nearest boundary and the standard deviation of the refractive index. The results illustrate the ubiquity of refractive index fluctuations and the elegance of Medwin’s model. [Work supported by Office of Naval Research, Ocean Acoustics.]
Observations of scattering attenuation in the Earth and implications for Q
Authors: Rector James
Published: October 2013

Seismologists often attribute the attenuation of a transmitted seismic pulse to anelastic absorption or Q. Real data suggests a different dominant mechanism. The earth, particularly in sedimentary basins, is heterogeneous on all scales. This heterogeneity results in a transmitted pulse being attenuated by scattering at every boundary it encounters. Theoretical models proposed by Zien and Shapiro (1994) suggest that scattering attenuation is angle dependent, but not necessarily frequency dependent, at least for short propagation distances. In this paper we review the mechanisms for transmitted pulse attenuation both scattering- and absorption-based. We then analyze real data and compare the contributions of these mechanisms to the observed attenuation.
Parametric acoustic array and P. J. Westervelt: A tribute
Authors: Foote Kenneth G.
Published: October 2013

Discovery of the parametric acoustic array, that is, its principle, by P. J. Westervelt [J. Acoust. Soc. Am. 35, 535–537 (1963)] is justly famous. Reasons are given for this claim, including its unprecedented character and its usefulness, which is witnessed by a number of operational acoustical devices whose applications span subbottom profiling, marine archaeology, mine detection, and fish swimbladder resonance absorption spectroscopy, among others. New applications continue to be found, as to backscattering by swimbladder-bearing fish for sizing and quantification. These applications may be supported and extended by current efforts to develop a standard-target calibration protocol. While the larger community has pursued such applications, while also defining limits to the performance of the parametric acoustic array, the achievement represented by the essential discovery remains undiminished. In this tribute, some comments are also made of a personal sort on Westervelt’s approach to science and teaching.
The role of vowel-to-consonant transitions in the perception of phonological consonant length
Authors: Hansen Benjamin B.
Published: October 2013

It has been noted [S. Kawahara, Univ. of Mass. Occasional Papers in Linguistics 32: Papers in Optimality Theory (2005)] that more sonorous consonants are less likely to occur as geminates in the world’s languages. Two experiments were performed to test whether a phonetic parameter, the vowel-to-consonant formant transition duration, relates to the possible neutralization of the length distinction for more vowel-like consonants. In a production experiment the consonant constriction and onset transition durations are measured for Persian geminate and singleton consonants spoken at three speaking rates. Stops, fricatives, nasals, liquids, glides, and glottal consonants are studied. Segments that are predicted to be less likely to occur as geminates have longer transitions at all speaking rates. A perception experiment based on manipulated palatal glide stimuli demonstrates that listeners have more difficulty categorizing a consonant as long or short if the transition is longer. Difficulty of categorization is measured both by reaction times and the slope of the curve-fitted cumulative identification model, where a flatter slope indicates a less distinct perceptual boundary.
Effect of nonlinear internal waves on midfrequency acoustic propagation on the continental shelf
Authors: Henyey Frank S. , Tang Dajun , Williams Kevin L. , Lien Ren-Chieh , Becker Kyle M. , Culver R. Lee , Gabel Paul C. , Lyons Joy E. , Weber Tom C.
Published: October 2013

Packets of nonlinear internal waves and strong sound-speed variability due to neutrally buoyant intrusions were measured in detail using a towed conductivity, salinity, pressure (CTD) chain. The measurements were taken in October 2005, on the continental shelf south of Rhode Island. Acoustic propagation through the measured sound-speed field is modeled. The waves in October are qualitatively different from the more familiar summertime nonlinear waves. Further measurements using the CTD chain will be made in the summer of 2006, in association with acoustic propagation measurements.
Auditory attention: One term for several concepts?
Authors: Gallun Frederick J.
Published: October 2013

The recent rise in the use of spectrally and temporally complex stimuli appears to be responsible for the increasingly frequent use of the term attention as an explanation of results in auditory experiments. It seems timely, therefore, to provide a broad examination of the various meanings often associated with this term. The goal of this session is to explore the ways in which the concept of auditory attention has been applied and perhaps suggest ways in which its application could be refined. An essential first question then is whether auditory attention refers to one concept or many. This talk will begin by examining the historical uses of this term and then proceed to outline some of the contemporary uses of the term, relating them back to the theoretical concepts the term is meant to represent. A specific example will be provided by reviewing a recent series of experiments in which the experimental designs were intended to manipulate listener attention and which were interpreted as providing insight into the mechanisms available for performing a variety of auditory tasks. [Work supported by NIH/NIDCD.]
Bat sonar and the role of frequency diversity
Authors: Foote Kenneth G. , Simmons James A.
Published: October 2013

Species of echolocating bats that forage in foliage, in the presence of clutter with attendant multiple, often overlapping echoes, use 3–5 simultaneous harmonic sweeps to cover a broad bandwidth, whereas species of bats that hunt only in the open use a single sweep to cover the same broad bandwidth. It is hypothesized that the frequency diversity evident in the presence of several harmonically related frequencies is vital to success in clutter. It is additionally hypothesized that the bat processes harmonic FM echoes in a manner tantamount to split-beam processing. Simultaneous determination of phase at several related frequencies enables the bat to distinguish between single and multiple targets, as in the theory of coincidence echoes [K. G. Foote, J. Acoust. Soc. Am. 99, 266–271 (1996)]. The plausibility of the second hypothesis is gauged by computations based on empirical knowledge of the signal parameters and timing acuity of the big brown bat (Eptesicus fuscus).
Vertical directionality of midfrequency surface noise in downward-refracting environments
Authors: Clark Cathy Ann
Published: October 2013

The vertical directionality of ambient noise due to surface agitation in the midfrequency range (0.5 to 10 kHz) for a subsurface receiver has a characteristic shape, knowledge of which may enhance shallow-water operations. In general, the noise level is highest at upward-looking angles and attenuated at downward-looking angles depending on the nature of the bottom. In environments with a negative profile gradient, the noise level is also greatly reduced in a low-angle shadow zone or ‘‘notch’’ at angles around 0 deg. This paper reviews the character of vertical noise directionality by examining a small number of measured data sets and considering the underlying physical mechanisms that drive the form of the distribution. A discussion of the implications for receiving sonar systems is followed by model reproduction of the measured data sets.
HF propagation in the ocean waveguide: Progress and open issues
Authors: Porter Michael
Published: October 2013

The HF band, defined for this talk as 5–50 kHz, has become of interest to us for many reasons. This operating band includes the musical chords and less-musical hisses of acoustic modems, the whistles and clicks of the common dolphin, and the newly recorded sounds of beaked whales. This band is of interest for mine hunting and torpedoes. Further, new HF tomography systems are emerging that exploit this band to produce lightweight systems to image the ocean weather, including both thermal fronts and currents. In turn, the latter are particularly important to lightly powered autonomous vehicles and gliders. To the surprise of many used to lower-frequency systems, sound in this band can produce identifiable echoes involving many reflections from a sea surface broken by waves and quite rough ocean bottom. Thus, the role of both dynamic and static boundaries is important, as well as refractive effects of the ocean volume. We review recent progress and discuss open issues in this area.
Demonstrations and experiments: The life-blood of acoustics education
Authors: Hansen Uwe J.
Published: October 2013

You hear: You forget; You see: You remember; You do: You understand. Acoustics represents a science discipline with very broad appeal. It is essential, both for the well being of the field, as well as the influence of science at large, to generate enthusiasm for science in general and acoustics in particular in our young people. Thus educational outreach is vital. The effectiveness of that outreach is closely related to the direct involvement of the students. A number of examples of demonstrations and hands-on experiments will be shown. They include acoustic levitation, mode studies, Dan Russell’s web site, and video animations of modal analysis studies in several musical instruments.
Speech privacy: What’s new? What’s next?
Authors: Bradley John S. , Gover Bradford N.
Published: October 2013

This paper will review recent work that has considered speech privacy criteria in open-plan offices and the development of new procedures to assess the architectural speech security of closed offices and meeting rooms. For open-plan offices, new subjective studies have confirmed the validity of a speech privacy design goal of SII no more than 0.20 (AI 0.15) and that an ideal masking noise level is ∼45 dBA. For the speech security of closed meeting rooms, subjective studies have developed new weighted signal-to-noise ratio measures for rating the privacy of meeting rooms and a new measurement procedure has been developed to assess conditions close to the outside boundaries of a meeting room. While much progress has been made, further work is still required. For example, it is now clear that in many situations, privacy is significantly influenced by both signal-to-noise and reverberation in the rooms. Both factors must be included when assessing the privacy of situations with significant amounts of reverberation.
Acoustical differences in mothers’ speech to children with cochlear implants versus normal-hearing children
Authors: Bradley Rose , Bergeson Tonya R. , Richie Carolyn
Published: October 2013

Infant-directed speech includes higher pitch overall and more exaggerated pitch contours compared to adult-directed speech. Clear speech is characterized by increased duration and expanded vowel space compared to conversational speech. This study investigated the differences between mothers’ speech to children with cochlear implants versus normal-hearing children in terms of acoustic characteristics associated with infant-directed speech and clear speech. Ten mothers of children with cochlear implants, 12- months postimplantation, and 25 mothers of normal-hearing, 12-month-old children were recorded during a 5-min play session between mother and child. Pitch range, vowel duration, and vowel space in mothers’ speech to children with cochlear implants and normal-hearing children were examined. Results are discussed in terms of differences between groups depending upon the hearing status of the child, and in terms of the acoustic characteristics of infant-directed speech and clear speech directed toward hearing-impaired listeners. [Work supported by NIH-NIDCD Training Grant T32DC00012 to Indiana University and NIH-NIDCD Research Grant R21DC06682 to the Indiana University School of Medicine, HUG grant Butler University.]
Low-frequency noise from a bubble plume formed by a plunging water jet
Authors: Buckingham Michael J.
Published: October 2013

Wind-driven, low-frequency ambient noise in the ocean may be due to bubble clouds created by wave breaking. To investigate this idea, a laboratory experiment was performed in which a vertical jet of fresh water plunged into a fresh water pool, to form a conical plume of bubbles beneath the surface. Both the jet speed, uj, and the air entrainment ratio, q, were carefully controlled and monitored. The power spectra of the sound from the plume, measured with an adjacent hydrophone, exhibit a sequence of nonuniformly spaced peaks below 1 kHz, which are associated with the resonances of the bubble-plume cavity. Each eigenfrequency scales accurately as (1/uj)1/2 and approximately as (1/q)1/4. A theoretical analysis of these scalings, based on a momentum-flux argument, shows that the sound speed profile within the plume varies as the square-root of depth down the axis. Using this square-root profile in the wave equation, an analytical solution for the pressure field within the plume is obtained, from which an explicit expression for the eigenfrequencies is derived. These theoretical eigenfrequencies, predicted from the conical geometry and square-root sound speed profile, exhibit the same nonuniform spacing and inverse-fractional power-law scalings as seen in the data. [Research supported by ONR.]