bluuebunny/crossref_metadata_2025 huggingface dataset:
The spread and density of the phonological neighborhood can strongly influence the verbal transformation illusion.
Authors: Bashford James A. , Warren Richard M. , Lenz Peter W.
Published: October 2013

When a recorded verbal stimulus repeats over and over, adaptation occurs and listeners hear competing forms. Reports of these “verbal transformations” (VTs) were obtained for 36 consonant-vowel (CV) syllables that varied both in frequency-weighted neighborhood density (ranging from 12.73 to 90.42) and in neighborhood spread [i.e., for 18 CVs, changes at either phoneme position could yield real words (spread = 2) while for the remaining 18 CVs, changes at only one position could yield words (spread = 1)]. The strength of the VT illusion, measured by the amount of time the stimuli were heard nonveridically during the 300-s repetition period, decreased substantially with both increasing neighborhood density [r=−0.74, F(1,34)=42.6, p<0.0001] and increasing spread [r=−0.75, F(1,34) = 44.1, p<0.0001]. Stepwise regression revealed that density and spread collectively accounted for approximately 70% of the variance in illusion strength [F(1,33)⩾10.0, p<0.003 or better]. These effects are larger than, but generally consistent with, neighborhood effects obtained with other psycholinguistic tasks, and they suggest that VTs can provide a highly sensitive measure of lexical competition. [Work supported by NIH.]
Speaking rate modulates lexical competition in online speech perception.
Authors: Reinisch Eva , Jesse Alexandra , McQueen James M.
Published: October 2013

Durational cues are used in online word recognition to disambiguate Dutch phrases such as “een(s) (s)peer” [“on(c)e (s)pear”]: The longer the [s], the more likely listeners consider the target to be [s]-initial [K. E. Shatzman and J. M. McQueen, Perc. Psychophys. 68, 1–16 (2006)]. Here, a series of eye-tracking experiments show that speaking rate affects perception of duration and thus modulates lexical competition online. Listeners’ eye-movements were recorded while they listened to sentences such as “Ze heeft wel eens peer gezegd” (“She once said pear”). Listeners had to click on printed targets (peer) presented on a computer screen with an [s]-initial competitor (speen; “pacifier”) and two unrelated distractors. When the preceding context is faster, the critical [s] should sound longer and match better the beginning of “speen.” Listeners indeed looked at the [s]-initial competitors more following fast than slow contexts. The opposite was found for [s]-initial targets (sneeuw; “snow”) with non-[s]-initial competitors (neef; “nephew”). Context adjacent to the target (i.e., wel eens) influenced target perception more than nonadjacent context. Nonadjacent context, however, was sufficient to modulate competition when adjacent context was spoken at the same rate as the target. Amount of nonadjacent context at a given rate affected only off line categorization.
The nonaccommodation of speech errors.
Authors: Gormley Andrea
Published: October 2013

Word-form speech errors are assumed to adapt to the unintended environment. For example, in the error ‘bads cat’ for intended ‘bad cats,’ the plural marker ‘s’ assimilates to the voicing of the ‘d’ in ‘bad.’ This phenomenon, called accommodation, provides evidence that the component responsible for errors is processed before the phonological assimilation component. Previous work on accommodation relies on the researcher to detect accommodation [D. Boomer and J. Laver, Br. J. Disord. Commun. 3, 1–12 (1968)]. Given that these studies are prone to perceptual bias, the conclusion that accommodation is the norm remains open. An acoustic analysis of errors was conducted to re-address this question. Thirty-two nonword tongue twisters, e.g., ‘tiff tivv tivv tiff,’ were designed to induce voicing errors on the coda. Because vowel lengthening before voiced codas is a phonological process in English, vowel length can be measured to detect accommodation. Errors were determined for each participant by measuring coda percent voicing and vowel duration in a control condition. Results from six participants (872 errors) show that while errors do accommodate (7.6%), nonaccommodation (40.7%) occurs more frequently. This result shows that errors do occur after phonological processing. [Work supported by OGS and Carleton University.]
Towards produtive language mapping: A magnetoencephalography study of letter naming.
Authors: Zhang Yang , Zhang Wenbo , Landsteiner Joel
Published: October 2013

This study aims to examine the sensitivity and specificity of magnetoencephalography (MEG) integrated with magnetic resonance imaging (MRI) for productive language mapping using a simple letter naming task. Six healthy adult volunteers participated after screening for handedness and medical history of speech, language, hearing, and vision. The data were collected using a 148-channel whole-head MEG system (Magnes WH2500, 4D Neuroimaging, San Diego) at the Magnetic Source Imaging Laboratory in United Hospital, St. Paul. During the recording session in a magnetically shielded room, the subjects were instructed to pay attention to the visual stimuli and articulate the letter from the English alphabet as soon as it was shown on the screen. The averaged epochs and trial-to-trial raw data were analyzed using Brain Electrical Source Analysis (BESA) and BrainVoyager software. Although visual processing of the letters showed similar temporal and spatial activation patterns, letter naming did not show uniform activation patterns in the Broca’s area. Large inter-subject variability was found in terms of superior temporal, inferior parietal, motor, and supplemental motor involvement. The results are discussed with respect to the technical challenges in implementing MEG with millisecond resolution for presurgical productive language mapping and potential risks of sensorimotor and language deficits.
Mismatch negativity reflects the affect of training on speech perception.
Authors: Jantzen McNeel Gordon , Cella Katherine
Published: October 2013

An adult’s ability to perceive speech sounds that do not occur in their native language is influenced by the relationship between the new and native language phonology and by the individual’s capacity to perceive acoustic differences. Individual differences are important: even after phonetic training, adults with similar language backgrounds exhibit significant individual differences in their ability to learn difficult non-native speech sounds [Polka (1991); Pruitt, Strange, Polka, & Aguilar (1990)]. Neurophysiologic changes due to learning are also reflected in the mismatch negativity (MMN) response and are indicative of the effects of training [Naatanen et al. (1993) and Kraus et al. (1995)]. The present experiment included two groups of six normal-hearing monolingual American-English speakers. The experimental group was trained to identify a voiced, unaspirated, dental stop consonant. The control group received no training on the dental. Electrophysiologic responses were measured for both groups in response to the dental and alveolar contrasts using a perceptual mapping procedure. Training improved the experimental group’s ability to perceive the non-native contrast. Training effects were also reflected in the MMN response, as observed by increased duration and decreased onset latency.
Masking release at low sensation levels.
Authors: Nelson Peggy , Anderson Crump Elizabeth , Nie Yingjiu , Hawkinson-Lewis Michelle
Published: October 2013

Previous results have shown that listeners with sensorineural hearing loss (SNHL) obtain about half of the masking release of their normal-hearing (NH) counterparts. When speech is amplified sufficiently, listeners with SNHL may score like NH listeners in quiet and in steady noise, yet may obtain only half of the expected release from gated noise. We hypothesize that some of that deficiency may occur because of the impaired listeners’ low speech sensation levels, which results in decreased usefulness of the speech signal in the noise dips. In the current study, NH listeners were tested for their recognition of IEEE sentences in quiet, in steady noise, and in gated noise with the speech presented at varying sensation levels. At low levels (10–15 dB SL), NH listeners scored nearly 100% correct in quiet. In steady noise (at −10 dB signal-to-noise ratio) scores for low-level stimuli were also similar to those obtained at higher SLs. However, at low SLs in gated noise, NH listeners demonstrated less masking release than expected, suggesting that audibility of speech in the dips of noise is important for masking release even when performance in quiet and in steady noise seems optimized. [Work supported by NIH 5R01DC008306.]
Seeing a speaker’s face helps stream segregation for younger and elderly adults.
Authors: Jesse Alexandra , Janse Esther
Published: October 2013

Listening to a speaker while hearing one or more competing speakers in the background can be a challenging task, especially for elderly adults. We show that younger and elderly listeners (above the age of 65) with varying degrees of age-related hearing loss benefit in stream segregation and speech processing from seeing the target speaker talk in addition to hearing an audio mix of a target and a competing speaker. This audiovisual benefit was found for response accuracy and speed in a phoneme monitoring task, where participants indicated by button press the occurrence of given target phonemes in the monitored speech of the target speaker. The audiovisual benefit was larger for younger than for older adults, despite their equivalent performance on auditory-only trials and in an off-line phoneme lip-reading task. Better lip-reading performance, however, predicted a larger audiovisual benefit. The audiovisual benefit was found for both highly visible phonemes (/p/) and poorly visible phonemes (/k/), but was modulated in its size by segmental visibility. The audiovisual benefit therefore arises from local segmental visual information but is also at least partially driven by audiovisual synchrony information that aids in attending to the target speaker.
The eyes’ footprints on the ears: An investigation of short-term speech intelligibility change.
Authors: Liang Jing , Small Steven L. , Nusbaum Howard C.
Published: October 2013

Although observation of mouth movements improves auditory speech perception, the extent to which visual information aids speech perceptual learning and affects subsequent audio-only speech perception remains unknown. The current study investigates whether visual speech information, specifically, the synchronized mouth movements of the talking face during training, helps the listener to perceive audio-only speech more effectively after training. An experimental group was trained to recognize audiovisual words presented in noise, while a control group was trained on the same audio speech signal in noise, but with no accompanying mouth movements. The control group provides a baseline estimate of what listeners can learn from the speech signal alone without visual information from the talker’s mouth movements. Both groups were tested on audio-only speech in noise before and after training. All novel words were used in the pretest, training, and posttest. The results demonstrate that visual information aids learning to recognize audio-only speech in noise, suggesting visual information from a talker’s mouth movements during training might change auditory coding of acoustic speech signals.
Influence of visual speech information on the identification of foreign accented speech.
Authors: Reed Rebecca K. , Auer Edward T.
Published: October 2013

Seeing a native talker’s face improves speech intelligibility in noise for native perceivers. The intelligibility of foreign accented speech (English spoken by native talkers of Mandarin) is more susceptible to the effects of noise than the speech of native talkers. [Rogers et al., Lang Speech 47(2), 139–154 (2004)]. The current experiment investigated the influence of seeing the non-native talker’s face on the intelligibility of speech presented in noise. Ten talkers (nine non-native and one native) were recorded producing 155 sentences each. Talker-specific speech shaped noise was mixed with the audio of the sentences. Eighty-one native perceivers of English (nine per non-native talker) responded to 20 sentences spoken by the native talker and 28 by the non-native talker in each condition (audio-alone, visual-alone, audiovisual). Open set identification responses were scored as percent words correct for each condition and talker. Preliminary analyses demonstrate that although seeing the non-native talker increases intelligibility, the gain is significantly reduced compared to the native talker. Results will be discussed in terms of potential sources of the audiovisual gain. These sources are hypothesized to be differentially sensitive to the distortions arising in non-native speech. [Work supported in part by NIH/NIDCD DC04856 and the University of Kansas, UGRA.]
Measurement and modeling of broadband Bragg scattering from a sinusoidal surface.
Authors: Tang Dajun , Jackson Darrell R.
Published: October 2013

While the mechanism of Bragg scattering is well known, most experimental work has been concentrated in the area of narrow band sound sources and in the far-field. Motivated by underwater detection problems in the presence of sediment ripple fields, we report laboratory measurements of broadband sound scattering from a sinusoidal surface machined on a polyurethane board. The surface has a wavelength of 8 mm and peak-to-peak height of 2 mm. Coherently scattered sound data were taken in near-field geometries and in the frequency band of 150–400 kHz. The measurement geometry is such that a broad range of Bragg angles corresponding to the frequency band are covered. We observe that the scattered sound demonstrates a down chirp time dependence when the incident sound is a short pulse. Models based on first order perturbation theory were developed which explain the observed scattered sound in both magnitude and phase. In addition, we also measured second order Bragg scattering. This motivates modeling efforts on higher order Bragg scatter. [Work supported by ONR.]
Validation of a physical model for surface clutter.
Authors: Philip Trudy L. , Newhall Bruce K. , Arvelo Juan I.
Published: October 2013

There is a strong need to more accurately represent active sonar system false contacts in various environments and conditions for the purpose of active acoustic simulation and synthetic training. A computationally viable approach for the generation of physics-based false contacts in a raw beamformed time series that can be injected into a sonar processor was previously developed for bottom clutter. That model is now extended for clutter due to rough ocean surface scattering, and is compared with ASIAEX01 data. Considerations in extending the existing model include: characterizing appropriate statistics of the rough surface, adding surface scattering clutter to the sonar model, evaluating the realism of the simulation, and evaluating the computational burden (for real-time trainers). The output of the simulation was analyzed for those considerations and then compared to the data. The use of a vertical line array allowed physical mechanisms in the data to be isolated, and their clutter data statistics separately determined. After comparing data statistics to predictions, the need for additional modeled clutter mechanisms was assessed. This effort was conducted under the auspices of the Undersea Warfare Business Area Independent Research and Development program of the Johns Hopkins University Applied Physics Laboratory.
Silver Medal in Speech Communication
Authors: Strange Winifred
Published: October 2013

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Gold Medal of the Acoustical Society of America
Authors: Rossing Thomas D.
Published: October 2013

The Gold Medal is presented in the spring to a member of the Society, without age limitation, for contributions to acoustics. The first Gold Medal was presented in 1954 on the occasion of the Society's Twenty-Fifth Anniversary Celebration and biennially until 1981. It is now an annual award.
Auditory temporal summation in pinnipeds.
Authors: Ghoul Asila , Holt Marla M. , Reichmuth Colleen , Kastak David
Published: October 2013

In addition to improving the understanding of auditory processing in pinnipeds, direct measures of temporal summation are relevant to the selection of signal parameters when conducting audiometric research, assessing the effects of signal duration on communication ranges, and evaluating the potential auditory impacts of anthropogenic signals. In the present study, individuals from three pinniped species were tested to determine how signal duration influenced pure-tone hearing thresholds. The psychophysical method of constant stimuli was used to obtain aerial thresholds for each subject at nine different signal durations ranging from 25 to 500 ms. Parameter estimates derived for a California sea lion (Zalophus californianus) from an exponential model of temporal summation yielded time constants (τ) of 176, 98, and 141 ms at frequencies of 2.5, 5, and 10 kHz, respectively. Preliminary results with a northern elephant seal (Mirounga angustirostris) at 5 kHz (this study), and a harbor seal (Phoca vitulina) at 2.5 kHz [M. M. Holt et al., J. Soc. Am. 116, 2531 (2004)] show similar values for (τ), 134 and 144 ms, respectively. These time constants are similar to those of other mammals tested and do not appear to vary with respect to frequency.
Analysis of most prominent signal features of humpback whale (Megaptera Novaeangliae) vocalizations towards the goal of autonomous acoustic classification.
Authors: Abbot Ted , Mayer Owen , Premus Vince , Abbot Philip , Dyer Ira
Published: October 2013

Humpback whale vocalizations were recorded using hydrophones on glider systems off Alaska in January 2000, in Hawaii in February 2008, and in the Stellwagen Bank National Marine Sanctuary in October 2007 and July 2008. The vocalizations have been grouped into five call types based on the most prominent signal features. Only five call types are used because autonomous species classification relies on the most consistent and repeatable signal features rather than the full diverse range of humpback vocalizations. The five call types are upsweep (increasing frequency over time), downsweep (decreasing frequency over time), flute (increasing and decreasing frequency over time), tone (little or no change in frequency over time), and groan (commonly a social or feeding-related vocalization, frequently characterized by unstructured broadband sound). We present detailed statistical analyses of these call types including bandwidth, minimum and maximum frequency, duration, and slope. A comparative analysis across data sets shows the relative frequency of occurrence of each vocalization type and indicates the degree of temporal and geographic variation of Humpback vocalizations.
Is rejection of clutter achieved by disrupting perception of delay in bat sonar?
Authors: Bates Mary E. , Simmons James A.
Published: October 2013

Big brown bats (Eptesicus fuscus) emit frequency-modulated (FM) biosonar sounds containing two prominent harmonics, FM1 (55–22 kHz) and FM2 (105–145 kHz), and perceive target distance from echo delay. Ordinarily, echoes from objects arrive with both harmonics at the same delay, although FM2 becomes progressively more attenuated than FM1 with increasing target distance and off-axis direction. Off-axis or long-range echoes naturally undergo lowpass filtering, which causes significant loss of acuity. Misalignment of FM2 with respect to FM1 or selective removal of low-end frequencies disproportionately affects the accuracy of delay perception. Delay acuity is sharp for echoes containing both harmonics, less sharp for echoes containing only FM1, and very poor for echoes containing only FM2. Acoustically unnatural highpass filtering to remove low-end frequencies from FM1 causes acuity to collapse. Attenuation of FM2 relative to FM1 by 3 dB decreases delay acuity, but shortening of the delay for FM2 by 48 μs counteracts amplitude-latency trading and restores delay acuity. Bats may have a spatial perceptual “fovea” covering a narrow zone in front of them for high-acuity perception surrounded by a zone of much lower acuity that suppresses the perceptual salience of background clutter. [Work supported by NASA RI Space Grant and ONR.]
Range discrimination of multiple objects from the echo spectrogram measured by using the frequency modulation sound.
Authors: Matsuo Ikuo
Published: October 2013

Using the echolocation, bats can capture moving objects in real 3D space. Bats emit the frequency modulation sound and can identify objects with an accuracy of less than a millimeter. To determine delay times of multiple objects requires estimating the sequence of delay separations by extracting temporal changes in the interference pattern of the echoes. The models to determine delay times of multiple objects from the simulated echoes by using the frequency modulation sound have been previously proposed. In order to extract the temporal changes, Gaussian chirplets with a carrier frequency compatible with emission sweep rates were used. The delay time for first object can be estimated from the echo spectrum around the onset time. The delay time for second object is obtained by adding the delay time for the first object to the delay separation between first and second objects (extracted from the first appearance of interference effects). Further objects can be located in sequence by this same procedure. In this paper, these echoes were measured from multiple closely spaced objects, and it was examined that this model could estimate each delay times of these objects.
An evolutionary approach to perissodactyl vocalizations.
Authors: Browning David G. , Scheifele Peter M. , Dhar Pranab K. , Kim Jong-Myon
Published: October 2013

Approximately 65 million years ago, dinosaurs were displaced by mammals. In a then highly forested world, the perissodactyls (odd-toed ungulates) became the largest group of large mammals, consisting of an estimated 15 families. We hypothesize that they started to develop a melodic component in their tonal vocalizations in order to provide identity in this restricted visibility setting. With time, large areas shifted to grassland, favoring mammals with compound stomachs, namely, artiodactyles (sheep, cattle, etc.) and resulting in the decline of the perissodactyls to only three families (equines, tapirs, and rhinos) today. Although all the remaining perissodactyls still retain a melodic component in their vocalizations, it appears to be less developed in those that adapted to the open grassland environment, such as the plains zebra. There a simple tonal call (as the artiodactyles have, too) is sufficient to draw attention; additional information can be obtained visually. On the other hand, those that continued in a forested location such as the Sumatran Rhino have developed a more lyrical call to compensate for reduced visibility.
Sonothrombolysis for acute coronary syndromes: Opportunities and challenges.
Authors: Kaul Sanjiv
Published: October 2013

Percutanous interventions and pharmacological thrombolysis are the current options for treatment of acute coronary syndromes (ACS). The former is limited by its availability and the latter by its efficacy. Sonothrombolysis has been demonstrated to be effective in achieving tissue perfusion in the peripheral arteries as well as in cerebral arteries. Therefore, there is potential of using sonothrombolysis for the treatment of ACS. An ultrasound imaging and delivery system could overcome the issue of access while combining it with microbubbles and low dose thrombolytics could result in a high reperfusion rate. Furthermore, the direct effect of ultrasound on ishemic myocardium (release of nitric oxide and increase in myocardial blood flow despite total coronary occlusion) could be exploited to protect the myocardium until reperfusion has been achieved. The success of reperfusion could be assessed in real-time using microbubbles. In order to achieve these goals, we need to plan systematic in vitro and in vivo studies to better understand the mechanics of sonothrombolysis. We also need to develop 4D combined imaging and ultrasound delivery systems. Positive developments in this field can translate into a major impact on human health world wide.
Targeted microbubble technology and ultrasound-mediated gene delivery.
Authors: Lindner Jonathan
Published: October 2013

There is interest in harnessing the energy from ultrasound-microbubble interactions for therapeutic gain. Microbubbles (MB) can be used as vectors for ultrasound mediated gene delivery (UMGD). This process relies on coupling cDNA to MB that undergo cavitation resulting in delivery/transfection from controlled bioeffects. Proximity of gene-laden MB to the vessel wall is a critical determinant of UMGD, which may be enhanced by the use of targeted MB probes that bind to certain disease states. In this presentation, endothelial targeting strategies will be discussed together with their recent application to optimize UMGD. Flow chamber and intravital microscopy studies have been performed that demonstrate that the coupling of cDNA and MB surfaces does not interfere with binding of these agents to counterligands on the vascular endothelium. Imaging experiments have also been performed demonstrating that MB retention in tissue using an ischemia-targeting approach is possible with gene-laden MBs targeted to endothelial cell adhesion molecules. Finally, data on the relative transfection efficiency of reporter genes with UMGD using a targeted versus control MB vector approach will be discussed. The overall conclusion of the presentation is that the ability to target MB to disease-related molecules may increase both efficiency and specificity of tissue transfection.
Gas body destruction reduces the effective circulating dose of ultrasound contrast agent infused in rats.
Authors: Miller Douglas L. , Dou Chunyan , Wiggins Roger C.
Published: October 2013

Glomerular capillary hemorrhage (GCH) in rat kidney provides a model system for assessing in vivo gas body efficacy in diagnostic or therapeutic applications of ultrasound. Two diagnostic ultrasound machines were utilized: one monitored the second-harmonic B mode contrast-enhancement of the left kidney and the other exposed the right kidney for GCH production. Definity contrast agent was infused at 5 μl/kg/min for 300 s during shams and 1.5-MHz intermittent exposures at 2.3-MPa peak rarefactional pressure amplitude in groups of five rats. The left kidney image brightness enhancement, indicative of circulating gas body dose, was 18.4 au (decompressed arbitrary units) in shams with no GCH in histology. Exposure of the right kidney with a normal 1-s image interval induced 68.4% GCH but reduced the left kidney enhancement to 3.3 au, which implies substantial gas body destruction. Decreased exposure with 10-s interval reduced right kidney GCH (P′<0.001) but only to 30.3% while ameliorating gas body destruction with 13.1-au left kidney enhancement. The effective in vivo gas body dose in rats may be reduced greatly due to gas body destruction in the small animal, complicating extrapolation to similar conditions of human exposure. [Work supported by NIH grant EB00338.]
Direct observation of microbubble interactions with ex vivo microvessels.
Authors: Chen Hong , Brayman Andrew A. , Bailey Michael R. , Matula Thomas J.
Published: October 2013

The interaction between microbubbles with tissue is poorly understood. Experimental evidence, supported by numerical simulations, suggests that bubble dynamics is highly constrained within blood vessels. To investigate this further, a high-speed microimaging system was set up to study the effects of acoustically activated microbubbles on microvessels in ex vivo rat mesentery tissues. The microbubble-perfused tissues were placed under a microscope and insonified with MHz ultrasound. A variety of interactions was observed by a high-speed camera: arterioles, venules, and capillaries were all recorded to dilate and invaginate by activated microbubbles. For small diameter microvessels, dilation and invagination were nearly symmetric, and bubble-induced rupture of the vessel was observed at high pressure. For larger microvessels, the portion of the vessel nearest the bubble coupled the strongest to the bubble dynamics, and the extent of dilation was smaller than invagination. Tissue jetting toward the bubble was recorded in many cases. The interaction of multiple bubbles inside microvessels was also observed. Bubble oscillation, vessel wall velocity, and tissue jet velocity were quantitatively measured. Invagination of vessel walls, especially tissue jetting, may be the major mechanism for tissue injury by a bubble. [Work supported by NIH 5R01EB000350.]
Identification of impact sounds by professional percussionists.
Authors: Liu Ching-Ju , Lutfi Robert
Published: October 2013

The present study was undertaken to determine the best of the ear's ability to identify the sounds of impact produced by the simplest of resonant objects (bars, plates, and membranes). We hypothesized that best performance would be achieved by professional percussionists who have had many years experience striking such objects to achieve desired nuances in sound. Five percussionists and five nonpercussionist musicians were recruited as participants from the University of Wisconsin School of Music. Additionally, 10 nonmusicians were recruited from the University at large. In a standard two-interval, forced-choice procedure, with and without feedback, listeners were asked to judge the impact sound corresponding to: (1) the greater force of impact; (2) the harder of two mallets; (3) the denser of the two objects struck; and (4) the point of mallet contact closest to the center of the object. Sounds were synthesized according to the equations of motion derived from a simple physical model which has been used in past studies [cf. Lutfi et al., JASA 118, 393–404 (2005)]. Generally, the results provide little support for the hypothesis that professional percussionists are more adept than the rest of us at judging the properties of impact sounds. [Research supported by NIDCD.]
Research on parametric arrays in Russia: Historical perspective.
Authors: Ostrovsky Lev A.
Published: October 2013

This presentation is concerned with the Russian part of the history of parametric arrays (PAs). After the pioneering works of P. Westervelt in the United States and V. Zverev and A. Kalachev in Russia and a decade of relative isolation, Soviet and Russian researches became involved internationally in the work on the PAs and, more generally, of nonlinear acoustic beams. Several Russian institutions have been involved, including Moscow University, Andreev Institute of Acoustics in Moscow, Radiophysics Research Institute and Institute of Applied Physics in Gorky (now Nizhny Novgorod), Gorky University, Pacific Oceanological Institute in Vladivostok, and some others. Selected Russian contributions of different years are to be outlined in this talk, including: (1) The theory of nonlinear acoustic beams, e.g., the Khokhlov-Zabolotskaya- Kuznetsov equation and other models of nonlinear acoustic beams in application to the PA; (2) the limitation of the PA efficiency by shock wave formation; (3) possible enhancement of the PA radiation by bubble layers; (4) experiments in laboratory and in the ocean; and (5) some new developments such as generation of low-frequency shear waves by ultrasound beams with biophysical applications.
Reflections on the early days of parametric array research and development.
Authors: Muir Thomas
Published: October 2013

Following Westervelt’s classic paper (1960/1963), there was a period of laboratory exploration, involving small-scale experiments and theoretical modeling, with Orhan Berktay’s early work anticipating the significance of several practical applications. Robert Mellen organized the First International Symposium on Nonlinear Acoustics (ISNA) in 1968, which the preset author was privileged to attend. Research interest and momentum began to build, expanding to field and seagoing experiments, as well as computational modeling. Some of the seminal milestones and achievements of this period are identified and illustrated. These include theoretical work, which enabled new experiments, and vice versa, facilitated by research tool engineering. A number of classic problems were studied, including parametric transmission and the effects of finite amplitude attenuation. Applications to air, water, and sediment research evolved, including propagation and backscattering measurements, subbottom profiling, and modal effects and communication in shallow water. Parametric reception became a hot topic, along with its intricate signal processing. Focusing of finite amplitude beams was developed, involving the use of lenses, also utilized for steering and scanning parametric beams. The bandwidth capability of parametric interaction was recognized, as were parametric transients for echo-ranging. Imaging applications emerged for both harmonic and difference frequency radiations, and a spin-off to biomedical ultrasonics was forged. By the mid-1980s, a dozen ISNA symposia had been held and the field had blossomed.
The development of a 75 kilohertz phase steered active parametric sonar system for subseabed target detection.
Authors: Lepper Paul , Woodward Bryan
Published: October 2013

Parametric sonar systems offer a number of potential advantages over conventional sonar’s that has encouraged investigation and implementation of nonlinear acoustic effects into sonar systems by numerous groups since Westervelt’s discovery reported in 1956. The work represented here describes the development of an active parametric sonar system utilizing a 75 kHz primary frequency signal with measured secondary frequency generation from 1–22 kHz using a 2-D 729 element square array arranged into 13 staves of 54 elements each. The array, dedicated computer controlled signal synthesis and power amplifier systems were developed and tested during trials on the Fisheries Research Services trails site on Loch Duich, Scotland. Primary and secondary frequency source levels of 245 dB re 1 μPa-m and 195 dB re 1 μPa-m at 7 kHz were measured with −3 dB full angle beam-widths of 3 and 2.5°–7° for frequencies 3–11 kHz, respectively. Individual control of the thirteen stave (channels) allowed in-pulse scanning and beam steering across a 36° sector including demonstration of real-time dynamic stabilization in one plane. Results will be presented for implementation of the system into a towed body sonar used during sediment classifications trials off the coast of France and for target detection tasks in Scotland.
Parametric projectors protecting marine mammals from vessel collisions.
Authors: Gerstein Edmund R. , Gerstein Laura A. , Forsythe Steven E.
Published: October 2013

Marine mammals are vulnerable to ship collisions. Measurements of controlled ship passages through vertical hydrophone arrays demonstrate a confluence of propagation factors and near surface effects that obscure the sounds of approaching vessels which then pose serious detection challenges for marine mammals. Joe Blue, who first identified these challenges, later conceived of a parametric method to mitigate them. A highly directional, dual-frequency parametric array has been developed to reduce collision risks by selectively alerting only those animals in the direct path of approaching vessels. The system projector is comprised of multiple elements, band-centered to transmit a high carrier frequency along with a lower side band signal. A single-side band modulation and phase-shift method are employed. The non-linearity of water then demodulates the mixed high frequency carrier into a lower frequency waveform audible to both manatees and whales. The bow mounted array projects a narrow beam directly ahead of vessels, and “fills in” acoustical shadows to alert marine mammals of approaching danger. Controlled field tests of the manatee device in Florida's NASA wildlife refuge are proving effective. Real-world deployments on select Navy and DOD vessels are planned this year and sea tests of a larger whale system will start next year. [Funded by U.S. Department of Defense, Navy Legacy Resource Management Program.]
Strength and cardivascular fitness predict time-to-arrival perception of looming sounds.
Authors: Neuhoff John G. , Long Katherine L. , Worthington Rebecca C.
Published: October 2013

Perceiving rapidly approaching sounding objects can be critical for survival. In studies of “auditory looming” perception, listeners consistently perceive sound sources as closer than they actually are, resulting in an underestimation of arrival time (Neuhoff, Planisek, and Seifritz, 2009; Rosenblum, Carello, and Pastore, 1987). This effect has been argued to provide an evolutionary advantage by allowing more time to prepare for the source. However, critical to this argument is the timely engagement of motor behaviors. Here, we tested the hypothesis that listeners with lower levels of physical fitness would have a larger anticipatory bias in perceived auditory arrival time, and thus a larger margin of safety in response to looming sounds. Listeners judged the arrival time of a three-dimensional looming sound. Physical fitness was measured using recovering heart rate after exercise and grip strength. Results show that the anticipatory bias in perceiving looming sounds is negatively correlated with physical fitness (r=−0.41). Those least prepared physically to interact with a looming sound source have a greater perceptual margin of safety. The findings are consistent with an evolutionary explanation of the anticipatory bias for looming sounds and provide evidence for fitness-based perception-action links between the auditory and motor systems.
How visual cues help us understand speech in a complex environment.
Authors: Kong Lingqiang , Shinn-Cunningham Barbara
Published: October 2013

At a cocktail party, visual cues may help a listener by showing them where or when to direct attention, what acoustic modulations a target utterance contains, and/or what articulatory gestures produce the target. Here, we investigated target speech intelligibility while varying the visual cues available in a complex, confusing auditory scene. In all cases, subjects listened for a target utterance in the presence of multiple masker utterances with similar grammatical structure spoken by the same talker. The timing and direction of the target (and maskers) varied randomly, increasing the uncertainty about where and when to focus auditory attention. The number of correctly reported target key words measured performance. Performance tended to improve as the amount of visual information increased, particularly when masker phrases came from the direction of the target. Performance was generally similar whether listeners saw full videos of the target talker from the correct direction or only a static image of the talker at the right time in the correct direction. However, temporal information about where and when the target occurred improved performance over knowing only target location. Results suggest that in these scenes, visual cues aid target understanding by indicating where and roughly when to direct attention.
Stimulus continuity is not necessary for the salience of dynamic sound localization cues.
Authors: Macpherson Ewan A.
Published: October 2013

Correspondence between head rotation and resulting changes in interaural difference cues provides information about sound source location. We assessed whether source continuity or merely relative displacement is necessary for use of this dynamic localization cue. Low-frequency (0.5–1 kHz) noise-band targets, not correctly localizable in the absence of head motion or for motion duration <50 ms [Macpherson and Kerr, APCAM (2008)], were presented while the listener performed a practiced head rotation at 50 deg/s. The stimuli were either continuous (a single burst gated on and off as the head entered and exited a variable-width spatial window) or discrete (two 20 ms endpoint bursts, triggered as the head entered and exited the window). Human listeners reported the apparent location of the stimulus by orienting with their heads subsequent to the initial head rotation. The minimum head movement angle (MHMA) necessary to resolve front/rear ambiguity was measured for each stimulus type. Similar MHMAs of 5–10 deg were measured for continuous and discrete stimuli, suggesting that endpoint “snapshots'' providing only displacement information are sufficient for use of dynamic localization cues. That parallels the finding that stimulus continuity does not improve detection of source motion [Chandler and Grantham, J. Acoust. Soc. Am. 106, 1956–1968 (1992)]. [Work supported by NSF and NIH/NIDCD.]
Tutorial: Pattern recognition in acoustic signal processing.
Authors: Hasegawa-Johnson Mark
Published: October 2013

This tutorial presents a framework for understanding and comparing applications of pattern recognition in acoustic signal processing. Representative examples will be delimited by two binary features: (1) regression versus classification (inferred variables are continuous versus discrete); (2) instantaneous versus dynamic (inference algorithms consider only an instantaneous observation vector versus inference algorithms integrate observations with knowledge of system dynamics). (1. Regression) problems include imaging and sound source tracking using a device with unknown properties and inverse problems, e.g., articulatory estimation from speech audio. (2. Classification) problems include, e.g., classification of animal and human vocalizations and nonspeech audio events. Instantaneous classification and regression are performed using a universal approximator (neural network, Gaussian mixture, classification, and regression tree), regularized, if necessary, to reduce generalization error (resulting in a support vector machine, regularized neural net, pruned classification tree, or AdaBoost). Dynamic classification and regression are done by imposing a prior to characterize system dynamics. Depending on the prior, the resulting model may be called a hidden Markov model, finite state transducer, dynamic Bayesian network, or conditional random field (dynamic classification), or a Kalman filter, extended Kalman filter, or switching Kalman filter (dynamic regression).
Testing for periodicity in speech waveforms.
Authors: Arda Betul , Rudoy Daniel , Wolfe Patrick J.
Published: October 2013

Speech waveform segments can roughly be categorized as voiced or unvoiced, in accordance with periodicity properties of the glottal source, and inferring this classification from data is in turn an important task underlying a variety of speech classification problems. This presentation describes a formal hypothesis testing framework for the detection of periodicity in general acoustic sources, with application to online voiced/unvoiced segmentation of speech signals. Beginning with the classical approach of Fisher, a variety of test statistics are proposed and analyzed in this context. Asymptotic analyses are provided, along with simulations to demonstrate the efficacy of such methods in the presence of compound periodicities, harmonic structure, and the low signal-to-noise-ratio environments typical of real-world speech applications. [Work supported in part by DARPA, NGA, and NSF.]
Acoustic color of elastic objects near boundaries: High-fidelity, high-speed, 3-D finite-element modeling.
Authors: Burnett David S.
Published: October 2013

NSWC PCD has developed a computer simulation system for modeling the acoustic color (target strength versus frequency and aspect angle) of realistic 3-D objects that are near to or straddling the interfaces between different fluids. It employs high-fidelity finite-element modeling of acoustic scattering from elastic objects (fully 3-D physics throughout object and environment), implemented in a custom-designed, scalable-architecture, multiblade rack system that efficiently manages the modeling of different parts of the frequency spectrum. The system automatically runs hundreds of thousands of finite-element models, dynamically changing the mesh resolution and outer fluid boundaries of the models as they sweep over frequency, and it produces a variety of outputs, the principal one being an acoustic color contour plot. This paper will begin with a brief overview of the acoustic color simulation system, followed by the results of two experimental validations of the system: (1) scattering from an aluminum cylinder in free space, and (2) scattering from an aluminum cylinder straddling the interface between two different fluids. The simulated acoustic color results will be compared with experimental, numerical, and theoretical results presented in other papers in this session. [Work supported by ONR and SERDP.]
Passive striation based geo-acoustic inversion using ships of opportunity.
Authors: Heaney Kevin D.
Published: October 2013

The coherent interaction of acoustic multipaths leads to an interference pattern in range. As range changes, the locations of the peaks (and troughs) of this interference pattern shift (as the group velocities of the modes change) in a sometimes predictable fashion. The intensity pattern of a moving source, plotted as a function of range and frequency, is commonly referred to as striation patterns. These patterns are commonly observed in the passing of a loud surface vessel in the spectrogram of a single hydrophone. In this paper, a geoacoustic method is presented based upon the quantitative measure of striation slope (wave guide invariant parameter) and the striation spacing in frequency (reciprocal time spread). Both of these parameters are generally sensitive to the geo-acoustic parameters of the sediment. In 2003 this technique was applied to a passing surface ship [K. Heaney, IEEE JOE 29(1), 43–50 (2003)] and to a range-dependent benchmark case [K. Heaney, IEEE JOE 29(1), 88–99 (2003)]. The approach in these papers compared the measured acoustic observables with those from a table predicted by the forward computation using the broadband PE. Current implementation of the algorithm uses a Gaussian beam code to efficiently compute the acoustic observables.
Investigation of bistatic invariance principles for active sonars.
Authors: Turgut Altan , Gauss Roger
Published: October 2013

Application of bistatic invariance principles to mid-frequency active sonar systems is investigated using data collected during two recent experiments conducted at the Malta Plateau and East China Sea. Low-frequency (350–650 Hz) and mid-frequency (1.5–3.5 kHz) LFM pulses were transmitted and direct-blast and return signals from an echo-repeater and several strong scatterers simultaneously recorded on a towed array, a drifting volumetric array, and a moored vertical line array. At low frequencies, application of bistatic invariance principles to target detection is demonstrated. At mid-frequencies, the spectrograms of the direct-blast signals showed regular striation patterns that were used to estimate the waveguide invariant parameter beta. However, both measured and simulated spectrograms of the signals scattered from an oil rig indicated the complexity of the striation patterns. More complex patterns of striations in the measured spectrograms might be due to azimuthal dependency of the scattering kernel, source/receiver motion, and low SNR. [Work supported by the Office of Naval Research.]