bluuebunny/crossref_metadata_2025 huggingface dataset:
Pitch perception in electric and acoustic hearing
Authors: Carlyon Robert P.
Published: October 2013

In normal hearing (NH), timing and place-of-excitation cues to pitch are usually inextricably linked. In contrast, by varying the temporal pattern of electrical pulses applied to one channel of a cochlear implant (CI), researchers can investigate the usefulness and limitations of purely temporal cues to pitch. A related technique, which often produces very similar results, is to present NH listeners with trains of acoustic pulses that have been passed through a fixed bandpass filter so as to remove place cues. Furthermore, one can then measure how these temporal patterns are represented in the auditory nerve (AN) by recording, respectively, the electrically and acoustically evoked compound action potential. These physiological measures can then be compared to listeners’ pitch judgements to the same stimuli. We have used this approach to show how AN refractory effects can influence pitch, to evaluate competing pitch models, and to show how a code based on first-order intervals can provide a level-independent representation of pitch. We have also examined the possible basis for the relatively poor pitch perception of CI users, particularly at pulse rates above about 300 pps. [Work supported by RNID.]
The neural representation of pitch in the auditory brainstem
Authors: Winter Ian
Published: October 2013

How the pitch of complex sounds is represented in the discharges of single or populations of neurons in the auditory brainstem is still unknown. In the ventral cochlear nucleus (VCN) each of the three main response types, primarylike, chopper, and onset, have all been implicated. Primarylike units maintain a good temporal representation of the pitch, similar to that found in the incoming fibres of the auditory nerve; chopper units can enhance the periodicity of complex sounds when it matches their chopping rate while onset units can show a particularly robust response to the periodicity of complex sound. However, various problems are faced by each of these unit types in explaining all aspects of pitch perception. In the inferior colliculus the theory that has dominated our thinking on the representation of the pitch of complex sounds has been that of the modulation filter bank, which runs orthogonal to the iso-frequency laminae in this nucleus. This modulation filter bank hypothesis has been linked with the periodicity tuning observed in some chopper units in the VCN, but many questions remain to be answered. In this review talk the successes and failures of these ideas will be discussed.
Brain imaging of pitch processing in human auditory cortex
Authors: Hall Deborah , Plack Christopher
Published: October 2013

Recent data from human fMRI and primate electrophysiological studies suggest that a region near the anterolateral border of primary auditory cortex may be involved in pitch processing. Collectively, these findings present strong support for a single central region that is selective for pitch, irrespective of its spectral characteristics. Most of the human neuroimaging studies addressing this issue have used iterated rippled noise (IRN), a specialized stimulus, to evoke a pitch sensation. In the present fMRI study, IRN did indeed activate the lateral portion of the primary auditory cortex on Heschls gyrus (HG). In contrast, the other pitch-evoking stimuli tested, including a variety of pure and complex tones, and Huggins pitch (a binaural pitch dependent on a combination of information from the two ears), did not activate lateral HG. Although there were individual differences, the most common locus was posterior to HG in planum temporale. We suggest that features of IRN not related to pitch may be responsible for the earlier results, and that it may be premature to assign the pitch center to lateral HG.
Nearfield acoustical holography and nonlinear sound fields
Authors: Maynard J. D.
Published: October 2013

Nearfield acoustical holography (NAH) has become a well-established method for studying sound radiation from noise sources. One of the advantages of the technique is that it may be implemented with fast computer algorithms. While the customary application assumes linear sound propagation, a current application is for noise from jet engines, where pressure amplitudes in the nearfield are high and sound propagation is nonlinear. A method for treating nonlinear sound fields with NAH, permitting high speed calculation, is being developed. An interesting problem arises from the result that nonlinear effects produce a source field which is distributed in a volume, while NAH treats sound fields on surfaces. A method for converting nonlinear volume sources to surface fields, together with NAH processing, will be presented.
High-frequency reconstruction of radiation patterns from a rectangular baffled plate using the Helmholtz equation least squares method
Authors: Lu Huancai , Wu Sean , Keele Donald
Published: October 2013

The Audio Engineering Society (AES) Standards require that full-sphere polar measurements of a sound field be taken at a very fine angular increment (1 deg) to ensure the accuracy in describing high-frequency radiation patterns of a source. This super fine angular resolution coupled with a far-field measurement requirement leads to an excessive number of measurements. For example, at 1 m and 1 degree angular resolution we would need more than 64000 measurement points. To alleviate this difficulty, the HELS (Helmholtz Equation Least Squares)-based near-field acoustical holography is used to reconstruct the radiation patterns. It is shown that HELS can provide accurate reconstruction of radiation patterns for dimensionless frequencies up to ka=25 based on the sound field sampled on a spherical surface at a rate lower than that required by AES Standards. HELS allows for accurate reconstruction even for sample spacing that violates the Nyquist spatial sampling rate in certain directions. In this paper, the convergence of HELS solutions is examined by comparing reconstructed radiation patterns with the analytic solution for a rectangular baffled plate. In particular, the impacts of the number of expansion terms in HELS and measurement points, and that of errors imbedded in the input data on the accuracy of reconstruction are analyzed.
Localization accuracy of advanced spatialisation techniques in small concert halls
Authors: Bates Enda , Kearney Gavin , Furlong Dermot , Boland Frank
Published: October 2013

A comparison of several spatialization systems is presented in terms of their localization accuracy under the nonideal listening conditions found in typical small concert halls. Of interest is the effect of real reverberant conditions, noncentral listening positions, and nonsymmetrical speaker arrays on source localization. The data are presented by comparison of empirical binaural measurements and perceptual listening tests carried out using Ambisonics, VBAP, SPAT∼, and Delta Stereophony systems. The listening tests are conducted by comparing the localization of phantom sources generated by the spatialization systems to sources generated by reference loudspeakers. The reference and phantom sources are presented at front, side, and back locations about a nine-listener audience, and the systems are tested in a random order with a calibrated 16-loudspeaker array situated nonsymmetrically around the audience area. The binaural recordings are compared to the subjective measurements of localization accuracy through the interaural level and time difference cues for each source position.
Localization with vector sensors in inhomogeneous media
Authors: Clark Joseph A. , Tarasek Gerald
Published: October 2013

Vector sensors detect and localize sources of radiated or scattered sound by simultaneously measuring pressure and particle motion near a single point. Experiments have revealed that the devices have remarkable localization capabilities greatly exceeding resolution limits predicted from considerations of diffraction effects caused by the device aperture. Fluctuations in the imaged position of a distant point source appear to result from inhomogeneities in the non-ideal (water) medium. These fluctuation effects can be mitigated by data averaging until limits imposed by statistical non-stationarity of the medium are reached. In this talk, experiments measuring the fluctuation of point source images will be described and a theory of the resolution achievable by vector sensors will be presented.
Spatial resolution of Helmholtz equation least-squares-based nearfield acoustical holography
Authors: Dziklinski Richard , Wu Sean
Published: October 2013

Traditional applications of near-field acoustical holography require that the acoustic pressures be taken at the Nyquist spatial sampling rate. For example, if the intended spatial resolution is 10 mm, then the spacing between measurement points should be 5 mm or less to ensure a target resolution. As a result, the total number of measurement points can be very high when a high spatial resolution in reconstruction is desired. The present paper examines the capability of using the Helmholtz equation least squares (HELS) method to reconstruct acoustic sources based on input data sampled at a rate lower than the Nyquist spatial sampling rate. Experimental results on two speakers separated by 9.53 mm are shown. A 4×4 microphone array is used with a spacing of 12.7 mm in the horizontal axis and 25.4 mm in the vertical axis, which is much larger than the spacing between the sound sources. Results show that if the coordinates of microphones are measured with a high accuracy (less than 2 mm) and the signal-to-noise ratio is 20 dB or higher, then these two sources can be reconstructed regardless whether the sounds are coherent or not. The reason for this phenomenon is explored in this paper.
Perception of Japanese mora nasal /N/ and mora obstruent /Q/ by native Japanese and English speakers
Authors: Nozawa Takeshi , Frieda Elaina M.
Published: October 2013

Japanese mora nasal /N/ and more obstruent /Q/ have no definite point of articulation. For instance, /N/ becomes [m] when a bilabial consonant follows and [n] when an alveolar consonant follows. /Q/ is also realized as [p], [t], or [k], depending on the point of articulation of the following consonant. Four native speakers of Japanese produced /N/ and /Q/ in /CVNCV/ and /CVQCV/ contexts, where the consonant after /N/ and /Q/ is always a stop. Their utterances were recorded and digitized. The word final /CV/ was edited out, and the stimuli with the structure of /CVN/ and /CVQ/ were created. Twelve native speakers of Japanese and American English were recruited as listeners in Shiga, Japan and Auburn, AL, respectively. The American listeners were told to identify the word final consonant in a multiple-choice format. The Japanese listeners were told that they were to tell whether /Q/ and /N/ were realized as [m], [n], [■], and [p], [t], [k], respectively. The American listeners outperformed the Japanese listeners despite the fact that they had had no prior exposure to Japanese. This is probably because a stop does not occur or no phonemic contrast is allowed in a postvocalic position in Japanese.
English vowel training with different first-language vowel systems
Authors: Iverson Paul , Evans Bronwen G.
Published: October 2013

This study examined whether native speakers of Spanish and German learn differently when given auditory training for English vowels. Spanish has fewer vowels (5) than does German (18). Spanish speakers thus need to acquire more vowel categories when learning English than do Germans, but the relative sparseness of the Spanish vowel space may actually facilitate learning (i.e., there is more room for new categories). Prior to training, the Spanish and German speakers were matched between groups in terms of their English vowel identification accuracy. Each subject completed a battery of pre/post-training tests (e.g., English vowel identification in quiet and noise; perceptual mapping of best exemplars) and were given five sessions of high-variability vowel identification training. The results demonstrated that the German subjects improved more in their English vowel identification accuracy (average 20 percentage-point improvement) than did the Spanish subjects (average ten percentage-point improvement). It appears that, rather than interfering with new learning, the relatively dense German vowel space facilitated the formation of new vowel categories, perhaps by making German speakers more sensitive overall to categorical distinctions.
Training segmental productions to improve second language intelligibility
Authors: Burleson Deborah F. , Dalby Jonathan
Published: October 2013

Training procedures that purport to improve the intelligibility of the speech of second language learners are often not validated by research. This study examines the effectiveness of English segmental intelligibility training for native Mandarin Chinese-speaking learners. Ten Mandarin Chinese speakers trained on 16 American English phonemic contrasts. Half of the participants trained on 16 vowel errors common in Mandarin-accented English and the other half on 16 common consonant errors. Each participant received 15 h of computer-based, minimal word-pairs training. Native American English listeners judged the intelligibility of pre- and posttraining recordings of isolated words read by the trainees in a two-alternative, forced-choice identification task. Listeners also judged the intelligibility of sentences produced by trainees and recorded pre- and posttraining. Results showed that training produced significant improvement in the intelligibility of isolated words included in the training and also in phonologically similar words not included in training. Vowel and consonant training participants made similar word-level improvement. The effect of word-level training on improvement in sentence intelligibility, while small, was also significant when results from participants in both vowel and consonant training groups were considered together. These results encourage continued exploration of structured computer-assisted pronunciation training to improve second language intelligibility.
Nonphonetic variability and speech categorization by native and non-native learners
Authors: Tuller Betty , Jantzen McNeel
Published: October 2013

Natural speech stimuli used in studies of phonological learning typically include several in talkers and phonetic environments because nonphonemic variability usually facilitates learning [e.g., Lively et al., J. Acoust. Soc. Am. (1993)]. In contrast, our previous work demonstrated that perceived talker variability in a synthetic test set markedly decreased the ability of monolingual American English subjects to distinguish between the voiced dental stop consonant and the voiced alveolar stop [d] [Jantzen and Tuller, J. Acoust. Soc. Am. (2006)]. Only the latter is phonemic in American English. There are several possible explanations for this that are currently being evaluated. Here we examine the effect of perceived talker variability on Malayalam listeners’ identification of three dental to alveolar continua that differ in F0. In Malayalam, both the dental and the alveolar stop consonants are phonemic. The results shed light on whether talker information and phonetic information share a representational structure. [Work supported by NSF and ONR.]
Production of lexical stress by Spanish speakers of English as a second language and its effect on perceptual judgments of intelligibility and accentedness
Authors: Edmunds Paul
Published: October 2013

Acoustic analyses of recordings of read speech were used to compare the production of lexical stress in multisyllabic words by Spanish ESL (English as a Second Language) speakers to that of native English speakers. The participants read short sentences containing multi-syllabic target words for which syllable duration, intensity, and fundamental frequency in the pronunciations of stressed and unstressed syllables were compared. Target words were equally divided based on syllable count, the syllable that should receive lexical stress based on native English pronunciation, and Spanish/English cognate status. Both orthographically identical cognates (e.g., radio) and orthographically non-identical cognates (e.g., necessary/necesario) were included. Average values of syllable duration, intensity and fundamental frequency were recorded across the speaker groups, and effects of cognate status on production were noted. Target words pronounced by the native speakers (to avoid differing segmental factors) were then resynthesized using the PSOLA algorithm to simulate the acoustic patterns of the ESL speakers. Native English listeners were asked to rate a set of stimuli embedded in a carrier phrase for intelligibility and accentedness. Results of the listening tasks suggest that variations in the acoustic properties under investigation may impact a listeners perception of speech intelligibility and accentedness.
Role of orthographic information in the auditory processing of novel L2 words
Authors: Escudero Paola , Hayes-Harb Rachel , Mitterer Holger
Published: October 2013

The English auditory word recognition of proficient Dutch-English bilinguals was examined in a follow-up study to Weber and Cutler (2004), who found, using eye-tracking technology, that these listeners could differentiate English /E/ and /ae/ in their lexical representations despite not being able to differentiate them in a perception task. The present study used the same eye-tracking method to test the hypothesis that knowledge of the spelled forms of words may allow learners to establish contrastive lexical representations for words containing perceptually difficult L2 contrasts. Fifty Dutch-English bilinguals learned nonword labels for nonobjects; some of the nonwords contained /E/ and some /ae/. One-half of the subjects were exposed to auditory forms and pictures only, while another set of subjects was additionally provided spelled forms of the words (the letters e and a differentiate /E/ and /ae/ words). At test, only subjects who received orthographic information during the word learning phase exhibited the same pattern found in Weber and Cutler (2004), providing support for the hypothesis that orthography can contribute to contrastive lexical representations, even for contrasts that are perceptually neutralized. The implications of these results for theoretical and applied issues in L2 speech processing will be presented.
On the perception of Korean and English sibilants in second language acquisition
Authors: Cheon Sang Yee
Published: October 2013

This study investigates the effect of phonetic similarity between L1 and L2 sounds on the perception of L2 contrasts. It employs hypotheses from Flege’s speech learning model as well as two types of assimilation patterns from Best’s perceptual assimilation model. L1 L2 phonetic similarities were measured perceptually and acoustically prior to the experiments. The first experiment examined the perception of the Korean voiceless sibilant contrast /s-s*/ by American English L2 learners. The second experiment examined the perception of the English voiceless sibilant contrast /s-■/ by Korean L2 learners. The findings of the first experiment show that a higher degree of phonetic similarity did not always result in good identification of L2 contrasts by American English advanced learners of Korean; overall, however, more similar L2 sounds were perceived better than less similar L2 sounds. In the second experiment, L2 contrasts that are acoustically and perceptually different from each other were perceived by L2 learners of Korean just as well as native speakers of American English perceived them. The results were not compatible with the predictions of either Best’s or Flege’s models, but the second result partially supported Best.
Cross-language perception of word-final stops: A comparison of Cantonese, Japanese, Korean, and Vietnamese listeners
Authors: Tsukada Kimiko , Ishihara Shunichi , Nguyen Thu T. A. , Roengpitya Rungpat
Published: October 2013

Four groups of Asian language speakers [Cantonese (NC), Japanese (NJ), Korean (NK), Vietnamese (NV)] were compared for their accuracy to discriminate English and Thai word-final stop contrasts (/p-t/, /p-k/, /t-k/). Word-final stops can be either audibly released or unreleased in English, whereas they are always unreleased in Thai. English (but not Thai) was familiar to all participants. In Cantonese, Korean, and Vietnamese, word-final stops are unreleased as in Thai. Japanese, on the other hand, does not permit word-final stops. All groups were more accurate in discriminating English than Thai contrasts. However, their response patterns differed according to their first languages (L1). NK was almost as accurate in Thai as in English while NJ was much better in English than in Thai. NC and NV were intermediate between NK and NJ. These findings suggest that experience with specific (i.e., unreleased) and native phonetic realization of sounds may be essential for accurate discrimination of word-final stop contrasts. However, in order to explain the differences between NC, NK, and NV in their discrimination of unreleased Thai stops, it is necessary to examine the robustness of phonetic cues to word-final stops in their L1s. The role of L1 experience in cross-language perception is discussed.
Regions that influence acoustic propagation in the sea at moderate frequencies, and the consequent departures from the ray-acoustic description
Authors: Spiesberger John
Published: October 2013

In the limit where a transient signal is comprised of very large frequencies, spatial regions within an inhomogeneous medium that influence the propagation from a source to a receiver lie along one or more ray paths. At lower frequencies for which the geometrical acoustic approximation is of borderline applicability, the regions that influence such transient signals are extended because of diffraction. Previous research has addressed the numerical determination of those spatial regions that influence propagation at low frequency. The present paper addresses the question of how high the center frequency need be so that the regions of influence are nearly described as ray paths for a model ocean in which the speed of sound increases nearly linearly with depth from a perfectly reflecting surface. Computations indicate that near 2500 Hz and at a range of 50 km, the region of influence resembles a ray. Noticeable departures from the ray picture are found at a range of 500 km. Various physical and mathematical causes for the departures from the ray propagation model for lower frequencies and for greater ranges are identified and discussed. [Work supported by the ONR.]
Three-dimensional coupled-mode model of propagation and scattering around a conical oceanic seamount
Authors: Luo Wenyu , Schmidt Henrik
Published: October 2013

Motivated by interesting anomalies observed in recent transmission experiments across the Kermit Seamount in the Pacific, a numerically efficient three-dimensional (3D) propagation and scattering model has been developed based on 3D coupled mode theory for axisymmetric bathymetry. The 3D coupled mode approach applied here is based on the same spectral representation of the field as earlier models presented by Athanassoulis and Propathopoulous [J. Acoust. Soc. Am. 100 (1996)] and Tarudakis [J. Comp. Acoust. 4 (1996)]. However, the earlier formulations were severely limited in terms of frequency, size, and geometry of the seamount, the seabed composition, and the distance of the source from the seamount, and are totally inadequate for modeling the Kermit experiment. By introducing a number of changes in the numerical formulation and using a standard normal mode model (CSNAP) for determining the fundamental modal solutions and coupling coefficients, orders of magnitude improvement in efficiency and fidelity have been achieved, allowing for realistic propagation and scattering scenarios to be modeled, including effects of seamount roughness, realistic sedimentary structure. By comparing to traditional n-by-2D coupled mode results, the model is used to demonstrate and investigate the surprisingly strong significance of 3D effects associated with propagation across oceanic seamounts such as Kermit, reaching up to the depth of the SOFAR channel. [Work supported by the US Office of Naval Research, Code 321OA.]
Low-frequency resonances from the circumnavigation of waves on plastic cylinders: Ordinary and evanescent-wave excitation
Authors: Espana Aubrey L. , Marston Philip L.
Published: October 2013

Resonances of cylinders provide useful information for separating signatures of targets of interest from the clutter of seafloor echoes. In prior work, the coupling of evanescent waves to low-frequency axial resonances of cylinders was investigated for targets in a laboratory-based simulated fluid sediment [C. F. Osterhoudt and P. L. Marston, J. Acoust. Soc. Am. 120, 3143 (2006)]. To facilitate investigations of the coupling to resonances associated with guided-wave circumnavigation, it is desirable to identify small cylindrical targets having appropriate regular resonance features visible with plane-wave illumination. The present investigation concerns such resonances on small polystyrene cylinders in water. Analogous features were previously modeled for acrylic spheres [B. T. Hefner and P. L. Marston, J. Acoust. Soc. Am. 107, 1930–1936 (2000)]. Those features were associated with the generalization of a Rayleigh wave on the solid. (Some other authors prefer to label these features as Scholte-Stoneley waves.) Measurements of the free-field acoustic backscattering by a small truncated polystyrene cylinder reveal the presence of analogous resonances. The measurements facilitate a comparison with approximations discussed by Stanton [J. Acoust. Soc. Am. 83, 64–67 (1988)]. Resonance excitation by evanescent waves was also confirmed. [Work supported by the Office of Naval Research.]
Wavefront modelling of pulse propagation
Authors: Tindle Chris , Deane Grant , Preisig James
Published: October 2013

Wavefront modelling has been developed for the rapid calculation of receiver waveforms in underwater sound pulse propagation. The method uses a solution of the wave equation which expresses the field as a sum over phase integrals. Each phase integral corresponds to a particular sequence of reflections or turning points and is evaluated analytically by using stationary phase approximations. Each point of stationary phase corresponds to a ray path. Pairs or triplets of stationary phase points correspond to caustics or foci and the phase and amplitude of the field is found directly. The method can handle rapid range dependence such as occurs with surface waves in shallow water and double scattering from the same surface. The method is fast and accurate and examples will be discussed. [Work supported by ONR.]
Probability density functions of acoustic modal amplitudes by polynomial chaos expansions
Authors: LePage Kevin D.
Published: October 2013

Polynomial chaos (PC) expansions have recently been derived to model the statistical behavior of complex modal amplitudes in uncertain waveguides. Here we explore the statistical trajectories of complex modal amplitudes in phase space for one and two degrees freedom (DOF) of waveguide uncertainty. It is shown that for one DOF of uncertainty, the modal amplitudes fall along a trajectory in phase space, while for higher DOFs the phase space of the amplitudes is space filling. Results are compared to phase space characteristics of the adiabatic and saturated limits of waveguide uncertainty, and a discussion of the range progression of the scintillation index of modal amplitude is undertaken. Comparisons between PC estimates of the probability density function of the modal amplitudes and Monte Carlo histograms are also made. [Work supported by ONR.]
Modeling marine mammal sound exposure maps for seismic exploration airgun arrays
Authors: Sidorovskaia Natalia A. , Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W.
Published: October 2013

Ocean seismic surveys rely on acoustic pulses produced by seismic airgun arrays for mapping ocean bottom layers in search of hydrocarbon indicators. Seismic exploration arrays produce mainly low frequency acoustic energy with a small amount of higher frequency content. It is known that the energy distribution in the ocean depends on both the array and the propagation-channel characteristics. A main concern for marine mammals is possible energy refocusing in depth and range due to waveguide propagation. Standard ocean propagation models are combined with industry airgun modeling packages to simulate the three-dimensional broadband acoustic field in the frequency and time domains for a seismic exploration array in typical Gulf of Mexico environments, including seasonally formed surface ducts. To emulate the accepted acoustic energy integration time for sperm whales, three-dimensional sound exposure maps are generated using a 200-msec integration window for transient seismic pulses. The maps are verified by comparison to available experimental data collected by the Littoral Acoustic Demonstration Center in a 2003 seismic calibration experiment. The proposed workflow can be integrated into procedures for predicting the environmental effects of seismic exploration surveys in waveguides. [Research partially supported by the Industry Research Funding Coalition through the International Association of Geophysical Contractors.]
Host shifts and the evolution of vibrational communication in treehoppers
Authors: Cocroft Reginald B.
Published: October 2013

Speciation in plant-feeding insects is associated with shifts to novel host plants. Along with differences in a suite of life history and fitness-related traits, closely related insect species that live on different host plants often differ dramatically in their communication systems. Differences in traits involved in sexual communication can provide a source of reproductive isolation and thereby facilitate speciation. Here the relationship between host shifts and changes in sexual communication is investigated in a group of host-specialist insects, the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae). Each of the eleven species in the complex has unique plant-borne signals used in the process of pair formation. Variation between species in female preferences and male signal traits indicates that closely-related species on different host plants have experienced divergent sexual selection. Changes in host use can also promote signal evolution through divergent natural selection on signal form and through phenotypic plasticity. Host shifts can thus have multiple effects on the evolution of communication systems in plant-feeding insects. [Work support for this research was provided by NSF.]
Vibrational risk assessment as a signal detection problem: Escape hatching of red-eyed treefrog eggs
Authors: Warkentin Karen M. , Caldwell Michael S. , McDaniel J. Gregory
Published: October 2013

The properties of cues from predators often overlap with background stimuli. Thus, prey may make two errors when assessing risk. They may miss cues and fail to defend themselves, or respond unnecessarily to false alarms. Although the incidence of these errors trades off, total error rates can be reduced only by adding information, either through increased sampling of one property or by sampling more cue properties. Adding cue properties likely increases processing requirements, and sampling predator cues entails risk. We examined a vibration-cued defense of the arboreal embryos of red-eyed treefrogs. These embryos use vibrations in snake attacks to cue behaviorally-mediated premature hatching and escape, but vibrations from benign sources rarely induce premature hatching. Missed cues and false alarms are costly; embryos that fail to hatch are eaten, and hatching prematurely increases predation by aquatic predators. Vibration playback experiments indicate that embryos attend to at least four nonredundant properties of vibrations: duration, spacing, stimulatory low frequencies, and inhibitory higher frequencies. They also adjust the amount of information they sample prior to hatching based on the time/risk cost of gathering it. This complexity of the risk assessment mechanism is consistent with strong selection against both missed cues and false alarms.
Parametric study of a shape based inversion for detecting high-intensity focused ultrasound lesions
Authors: Durning Bruno , Cleveland Robin O. , Miller Eric L.
Published: October 2013

A key problem in the practical use of high intensity focused ultrasound (HIFU) as a tool for cancer treatment is the non-invasive characterization of the regions of tissue that have successfully been necrosed. Previously, we proposed an approach to image guidance, based on the use of RF data obtained from a diagnostic ultrasound transducer and a shape-based inverse scattering approach. Specifically, it was assumed that the lesion has an ellipsoidal shape defined by its center, size, orientation, and contrast (in sound-speed and attenuation) compared to the background. An inverse-type method was used to identify the ellipsoid parameters from the RF data. In this work we explore the robustness of this approach to a variety of conditions likely to be encountered in practice, specifically, the presence of an aberatting layer in the path, the formation of non-ellipsoidal lesions, for example, a ‘‘tadpole’’ shaped lesion that is commonly formed during HIFU, and the presence of multiple objects. Experiments using a clinical scanner and tissue phantoms are reported and we evaluate the method’s efficiency to different shapes and number of objects. [Work supported by NIH and CenSSIS.]
Fast computation of spatial transfer function for ultrasound imaging
Authors: Guven Emre H. , Miller Eric , Cleveland Robin
Published: October 2013

A fast method for computing the spatial transfer function of ultrasound transducers is presented with application to rectangular transducers that are focused in one axis only. No closed form solutions exist for this application but several numerical techniques have been described in the ultrasound imaging literature. Our motivation is the rapid calculation of imaging kernels for physics based diagnostic imaging where current methods are computationally demanding. The spatial transfer function to be calculated is a spatial convolution of the transducer surface and the Green’s function. A 3-D version of the overlap-save method, which is a method for digital filtering of long data sequences, has been employed to obtain a fast computational algorithm. Further efficiency is gained by using separable approximations of the 3-D convolution through the singular value decomposition. The tradeoff between accuracy and spatial sampling rate is explored to determine appropriate parameters for a specific transducer. Comparisons with standard tools such as Field II will be presented. [Work supported by NIH and CenSSIS.]
Pulse-echo ultrasound in pulsed magnetic fields
Authors: Rickel D.
Published: October 2013

As the technology of high-speed data acquisition evolves along with the ability to record multi-megabyte continuous streams of data, the application of pulse-echo ultrasound to transient measurements have become possible. I will discuss a system that has been developed at the National High Magnetic Field Laboratory for measurements of sound speed and attenuation in materials subjected to intense pulsed magnetic fields. The magnetic field pulses have millisecond durations and can only be repeated a few times a day. We are able to process from a single magnetic pulse, a record of sound speed that reveals structural changes as a function of magnetic field. We are not alone in this effort; at least two other groups at other high magnetic field laboratories are using similar techniques [C. Proust et al., Lab. National des Champs Magnetiques Pulses, Toulouse France, UMR 5147CNRS-INSA-UPS; Wolf et al., ‘‘New Experimental Techniques for Pulsed Magnetic Fields-ESR and Ultrasonics,’’ Physica B 294–295, 612–17 (2001)]. This presentation is intended to acquaint the audience with the techniques of setting up a pulse-echo ultrasound system by taking advantage of modern digitizing systems available and computer based post processing using commercially available application software. I will present data from experiments that we have carried out and discuss the precision with which the sound speeds can be determined.
Thermal diffusivity of Bi2Sr2CaCu2O8 superconductor measured using open-cell photoacoustic technique: Effect of nano-Ag addition
Authors: Alwi Hasan A. , Narreto Mary A. B. , Wei Kong , Abd-Shukor Roslan
Published: October 2013

Thermal diffusivities of Bi2Sr2CaCu2O8 superconductor at room temperature with the addition of different amounts of nano Ag (Bi2Sr2CaCu2O8-Agx with x=0-1.0) were measured using the open-cell photoacoustic technique. The thermal diffusivity was obtained by analyzing the phase of photoacoustic signal of thermally thick samples instead of analyzing the amplitude signal of thermally thick-to-thin samples. Two methods of phase analysis of thermally thick samples were applied, that is, Calderon’s method and the thermal diffusion model. The phase analysis is suitable where the dominanant mechanism contributing to the photoacoustic signal is thermal diffusion alone, which is true for Bi2Sr2CaCu2O8 superconductor. We have found that the thermal diffusivity increases with the amounts of nano-Ag. The values of thermal diffusivity obtained were between 0.01250-0.00128 and 0.01606-0.00230 cm2/s for Ag0 to Ag1.0.
Laboratory rats do not use binaural time cues to localize sound
Authors: Wesolek Christina M. , Koay Gimseong , Heffner Henry E.
Published: October 2013

The use of binaural time and intensity cues to localize sound can be investigated by determining the ability of a subject to localize pure tones in a free-field. Specifically, the ability to localize low-frequency tones, which do not produce an intensity difference at the two ears, demonstrates the use of the binaural phase (time) cue whereas the ability to localize high-frequency tones, to which the auditory system cannot phase lock, demonstrates the use of the binaural intensity-difference cue. Because previous studies of the laboratory rat (Rattus norvegicus) disagreed on the highest frequency that could be localized using binaural phase difference, the ability of rats to localize pure tones was reexamined. The results indicated that, contrary to previous studies, laboratory rats are not able to localize low-frequency tones even when they are amplitude modulated. Thus, it appears that laboratory rats are unable to use the binaural time-difference cue to localize sound. Because the previous studies were conducted before the widespread availability of spectrum analyzers, it is possible that their results were due to the presence of high-frequency harmonics in their low-frequency tones. These results have relevance for the anatomical and physiological study of binaural processing in laboratory rats. a)Presently at Disney’s Animal Kingdom, Lake Buena Vista, FL.
Interactive acoustical intimacy exploration
Authors: Gibbs Bobby , Braasch Jonas , Krueger Ted
Published: October 2013

A novel methodology to explore salient cues for acoustical intimacy is presented. Subjects are instructed to modify a set of sliders in a virtual acoustical environment to correlate with three intimacy settings: low, medium, and high. As the experiment proceeds, subjects are allowed to audition their choices and make modifications to achieve what they feel to be optimal settings. At the conclusion of the interactive phase, subjects are instructed to rank the (as yet unknown to them) parameters in terms of their overall effect on intimacy. Unknown to the subjects, each slider correlates to an acoustical parameter: direct-to-reverberant energy ratio, high-frequency attenuation, room size, and volume. Results from the experiment are discussed relative to concert-hall acoustics and virtual spaces.
Diffraction of acoustic waves and embedding theory
Authors: Craster Richard V. , Skelton Elizabeth A. , Shanin Andrey V.
Published: October 2013

The diffraction and scattering of sound waves by sharp edges and corners is a ubiquitous feature of acoustic interactions with structures. This talk is on a technique called embedding which is a relatively new, and under used, idea in diffraction theory. The fundamental idea of embedding is that one only ever solves a single master, canonical, scattering problem (or set of problems). Thereafter, to extract the far-field behavior for any plane wave incidence on the same geometry, one only manipulates results from this master problem. The result is that quantities (directivities) previously dependent upon two parameters (incident and observed angle) become factorized into products of a function of a single variable, together with a simple trigonometric term; this facilitates rapid numerical evaluation. In principle, this should revolutionize many scattering calculations in every area where diffraction occurs as one need only evaluate the directivities from the set of canonical problems once. Given these directivities one manipulates them to generate solutions for more general problems, rather than continually recalculating and re-evaluating. At present, the theory has some limitations and the talk will cover these and describe how they can be overcome.
Representing sound energy, phase, and interference using three-dimensional signals
Authors: Vassilakis Pantelis N.
Published: October 2013

As graphic representations of vibrations/waves, sound signals capture only selected attributes of the phenomenon they represent. Assuming equivalence between signals and sound waves obscures the fact that 2-D signals are unfit to a) represent wave-energy quantities consistently across frequencies, b) account for the phase flip and alternating positive/negative amplitude values in modulated waves with AM-depth >100%, and c) represent the energy content of interference. The proposed sound-signal representation is based on the complex equation of motion describing a wave. It results in spiral sine signals and twisted-spiral complex signals, similar to complex analytic signals, with the imaginary component of the complex equation of motion representing the signal envelope’s argument (phase). Spiral sine signals offer a consistent measure of sine-wave energy across frequencies, while twisted-spiral complex signals account for the negative amplitudes observed in modulated signals, mapping the modulation parameters onto the twisting parameters. In terms of interference, 3-D signals illustrate that amplitude fluctuations and the signal envelopes that describe them are not just boundary curves but waves that trace changes in the total instantaneous energy of a signal over time, representing the oscillation between potential and kinetic energies within a wave. Examples of 3-D animations illustrating the proposed signals are presented.
Passive measurements of random wave fields in an instrumented structure
Authors: Fisher Karl A. , Chambers David H. , Lehman Sean K.
Published: October 2013

A passive measurement system using fiber Bragg gratings is presented to interrogate the health of an instrumented part. Estimation of the structures Green’s function from diffuse sound fields present during typical operating conditions is the basis for our approach. Experimental studies are conducted using coherent processing techniques of random and generated sound fields to investigate a structure for defects and/or deviations from an initial or pristine state. We are interested in developing a monitoring process that is minimally invasive and robust enough to survive the environment that the structure operates in and provide a quantitative assessment of the structure throughout its lifetime.
Church and concert hall acoustics
Authors: Hendrickson Charles
Published: October 2013

The separate acoustical criteria for churches and concert halls are presented from the viewpoint of a pipe organ builder—a former college physics teacher and president of the Associated Pipe Organ Builders of America. Developed from considerations of the different functions and purposes of churches and concert halls, the criteria are markedly different and even contradictory for these situations. Beranek’s ‘‘Music, Acoustics & Architecture’’ is referenced.
Underwater vocalizations of male harbor seals (Phoca vitulina) during the mating season at Brookfield Zoo
Authors: Clark Mehgan , Thomas Jeanette
Published: October 2013

Underwater vocalizations of harbor seals were recorded between April and October of 2006 in many settings, including male only, two females prior to the breeding season, and all seals as a group before, during, and after the breeding season. Recordings were made using a Dell XPS M140 laptop, with a linear frequency response up to 96 kHz, and Goldwave sound recording software. All recordings were analyzed using Spectrogram 14.0 software. Three call types were identified: short roars, long roars, and growls. A total of 736 roars were identified and 256 randomly sampled roars were analyzed. A total of 109 growls were identified and analyzed. The frequency range of the call types was 209 to 3406 Hz, based on dominant minimum and dominant maximum frequency measurements, and duration ranged from 0.8 to 10.5 s. The male produced stereotypical roars in late June. As there was only one male in the group, it is suggested that the function of this roar is to announce breeding condition or to attract a female for mating, not for competition among males.
Nocturnal activity by transient killer whales at St. Paul Island, AK
Authors: Newman Kelly , Springer Alan
Published: October 2013

Observations of killer whales in the act of predation are rare because feeding bouts are infrequent in relation to sighting opportunities, and they apparently feed at night as well as during the day. A pop-up autonomous recording unit (ARU) was used to expand the observation window of transient (mammal-eating) killer whales by monitoring them continuously from 22 June to 12 July 2006 near a northern fur seal rookery at St. Paul Island, AK, a predation hot-spot in the Bering Sea. The ARU recorded at a sampling rate of 0.5–16000 Hz. Killer whale vocalizations were detected on 19 of 20 days. Most vocalizations occurred from the end of civil twilight (00:26 on 1 July) through mid-morning. Fewest vocalizations occurred between 1800 and 2400. Vocal whales were most likely feeding, based on the paradigm that transients are mostly silent except when attacking prey. Call types are being identified and vocalizations are being correlated with visual observations and fur seal activity at the rookery. Nocturnal hunting is likely one important reason why it has been difficult to understand the foraging behavior of these elusive predators and must be considered when drawing conclusions about the roles transient killer whales play in marine ecosystems.