bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural basis of spatial hearing in reverberant environments.
Authors: Devore Sasha , Ihlefeld Antje , Shinn-Cunningham Barbara , Delgutte Bertrand
Published: October 2013

In reverberant environments, acoustic reflections interfere with the direct wavefront reaching a listener’s ears, distorting the spatial cues for sound localization. Yet, human listeners have little difficulty localizing sounds in everyday settings. Our research aims to elucidate the neural basis of spatial hearing in reverberant environments. Using a virtual acoustic space (VAS) technique, we investigated the effects of reverberation on the directional sensitivity of binaural neurons in the inferior colliculus (IC) of anesthetized cats and awake rabbits, focusing on neurons sensitive to interaural time differences. Consistent with the buildup of reverberant energy in a sound stimulus, we find that reverberation increasingly degrades the directional sensitivity of single neurons over time, although the amount of degradation depends on the characteristic frequency and the type of binaural cues available. The neurophysiological data can account for results from recent human psychophysical studies of spatial hearing in reverberant environments. In particular, we show how a population rate model for decoding the observed midbrain responses predicts the main trends in human lateralization performance, suggesting a subcortical origin for robust sound localization in reverberant environments. [Work supported by National Institutes of Health (NIH) Grant Nos. R01 DC002258 (BD), P30 DC005209 (BD), and R01 DC05778-02 (BGSC). SD partially supported by NIH Grant No. T32 DC00038 and the Helen Carr Peake Fund.]
Localization of amplitude modulated sounds and their echoes in the barn owl.
Authors: Nelson Brian S. , Takahashi Terry T.
Published: October 2013

Echoes that arrive after short delays are not perceived as events separate from sounds arriving directly from an active source, a phenomenon known as localization dominance. Studies have focused on the time-advantage at the onset of an echo/direct-sound pair to explain localization dominance. The head-saccades of barn owls and the responses of neurons in their auditory space maps were measured when sound pairs were gated simultaneously, so that the lead/lag relationship could be discerned only from the ongoing features of the envelopes. The owls behaved as though they experienced localization dominance at short delays, but only if the sounds were deeply amplitude modulated, suggesting the importance of the ongoing envelope. Correspondingly, neurons in the space map fired preferentially to the leading sound, thus paralleling the behavior, but again, deep amplitude modulations were necessary. Analyses of waveforms at the ears suggest that the acoustic features that caused the space map neurons to fire were more abundant for the leading than for the lagging stimuli, thus explaining localization dominance without the need for explicit echo-suppression circuitry. [Work supported by NIDCD F32-DC008267 and RO1-DC003925.]
Coding of sound features in primary and secondary auditory areas of songbirds.
Authors: Theunissen Frederic E.
Published: October 2013

We have used a combination of neuroethological and classical auditory neurophysiological approaches to study how behaviorally relevant sounds are processed in the avian auditory system. One of the contributions of the neuroethological approach has been the discovery of highly specific auditory neurons that appear to be specialized for detecting very specific behaviorally relevant sounds. On the other hand, many auditory neurons recorded in the auditory system of nonspecialists do not exhibit such specificity. At the same time, animals and humans hear and process a large space of sounds and are able to categorize these in much broader perceptual terms, describing them in terms of their pitch, timbre, and rhythm. By systematic analyzing neural responses to song in the ascending avian auditory system and relating receptive fields to the statistics of natural sounds, we have shown that these two approaches can be unified: we found that the spectrotemporal receptive fields of auditory neurons tile a subset of the acoustical space that is particular important for natural sounds. In addition, we found that neurons could be classified into functional clusters. Neurons in different clusters were sensitive to different song features and, we will argue, are involved in mediating distinct perceptual attributes.
On the time-mean state of ocean models and the properties of long-range acoustics.
Authors: Dushaw Brian D. , Dzieciuch Matthew A. , Worcester Peter F.
Published: October 2013

Global and regional circulation models of the ocean have the horizontal and vertical resolution required for realistic simulation of long-range acoustic propagation. These simulations offer a novel test of model accuracy, because acoustic propagation is sensitive to the vertical gradients of sound speed in the models and acoustic arrival patterns are known to have stable and universal properties. The travel time and dispersal of an arrival pattern are examples of such properties. Acoustic receptions on three long vertical line arrays from basin-scale transmissions in the North Pacific in 1996 and 1998 are used to test the acoustical properties of the time-mean state of several ocean models. The NOAA World Ocean Atlas, a global representation of the “average” ocean, yields acoustic predictions whose patterns closely match the observations, but not all ocean models accurately represent oceanic sound speed properties. Acoustical tests of a model do not necessarily require actual data, because basic acoustical properties may be derived from the World Ocean Atlas.
Comparison of apparent field sound transmission class (AFSTC) and outdoor indoor transmission class (OITC) as applied to modular classroom design and field analysis.
Authors: Philipp Norman H. , Wang Lily M.
Published: October 2013

Regarding the drafted addendum for ANSI S12.60-2002 Standard on Classroom Acoustics Guideline, it was recently proposed to utilize Outdoor Indoor Transmission Class as a means of rating modular classroom exterior envelope noise reduction performance. This paper provides a comparative analysis of Outdoor Indoor Transmission Class with the Apparent Field Sound Transmission Class. Measurements were conducted in modular classrooms currently in use by the Omaha Public School District in Omaha, NE, along with newer construction units prior to installation on-site. Limitations to both measurement methodologies are discussed in relation to their source noise spectrums.
The effective bandwidth of the enhanced transmission loss across a wall with Helmholtz resonators.
Authors: Garrelick Joel
Published: October 2013

It is long known that the introduction of Helmholtz resonators can enhance the transmission loss of a wall in the vicinity of their natural frequencies. Resonance is typically achieved by creating open-mouthed cavities in the wall. The effective bandwidth of the phenomenon is a key factor in its practical utility. It is dependent on the internal resonator resistance as well as the in situ external acoustic impedance at the cavity mouth. This paper is an analysis of the bandwidth for a variety of resonator configurations, including cavities with septa and differing volumes. The mathematical model, driven by a normally incident plane wave, will treat the wall as rigid but moveable, and the cavities will be infinitely periodic arrays. Influences of wall impedance, resonator resistance, cavity array spacing and natural frequencies will be described. In addition, the potential for minimizing the deleterious effects of diffraction between neighboring cavities by placing the cavity mouths on both sides of the wall will be assessed.
Active feedback control of broadband noise from a small axial fan.
Authors: Duke Cole V. , Sommerfeldt Scott D. , Gee Kent L.
Published: October 2013

In the past, significant progress has been made in actively controlling the tonal noise of axial cooling fans. Current work focuses on the control of broadband fan noise, which presents different challenges. Because the broadband noise is not deterministic, a feedback system will be used, and the total system delay must be reduced as much as possible. To ensure stability of the closed-loop control system, the phase and magnitude characteristics of the filter must be chosen to produce attenuation in the target frequency band without augmenting the noise outside the band. A practical analog feedback controller will be presented, and results will be shown for a single input single output control system, as well as a configuration using multiple independent control systems.
Real-time speech synthesis for neural prosthesis.
Authors: Guenther Frank H.
Published: October 2013

The idea of building an artificial vocal tract that could serve as a prosthetic device for mute individuals has been pursued since the pioneering work of Wolfgang von Kempelen and contemporaries in the 18th century. These early speaking machines were built out of wood, metal, rubber, and other materials fashioned into a mechanical vocal tract whose shape was manipulated manually by the user while air was forced through it. In the mid-20th century, Gunnar Fant and colleagues constructed electrical resonating circuits capable of producing speechlike sounds over loudspeakers, and shortly thereafter fully computer-based speech synthesizers were developed, including formant synthesizers and articulatory synthesizers. The recent development of brain-computer interfaces driven by neuronal activity raises the possibility of a speech prosthesis that would allow mute paralyzed individuals to directly control a speech synthesizer to create speech output. We have implemented such a brain-computer interface in a 25-year-old volunteer suffering from locked-in syndrome, characterized by complete loss of movement but intact perception and consciousness. To date the volunteer has successfully used the prosthesis to produce vowel sounds. Future developments in speech synthesis necessary for allowing full conversational speech via brain-computer interface will be outlined. [Work supported by NIH/NIDCD and NSF.]
Nonlinear viscoelastic response of the vocal fold lamina propria under large-amplitude oscillatory shear.
Authors: Chan Roger W. , Kimura Miwako
Published: October 2013

Viscoelastic properties of the vocal fold lamina propria have been reasonably quantified beyond the linear range for describing tissue behavior under uniaxial stretch or tensile deformation, but the same cannot be said for oscillatory shear deformation, which is more relevant for understanding the mechanics of large-amplitude vocal fold vibration. Previous studies reporting the viscoelastic shear properties of vocal fold tissues have been limited to characterization of the small-amplitude viscoelastic response in the linear viscoelastic region, partly due to the fact that derivation of the elastic and viscous shear moduli is based on the assumption of linearity, and also because of the lack of a coherent framework for describing any nonlinearities beyond the linear viscoelastic region. Based on a recently proposed rheological framework for quantifying such nonlinearities, this study examined the viscoelastic response of human vocal fold cover specimens subjected to large-amplitude oscillatory shear, up to a shear strain amplitude of around 1.0. Results indicated that the linear viscoelastic moduli (G′ and G″) cannot adequately describe the tissue response under large-strain shear deformation, whereas geometrical interpretations of Lissajous–Bowditch curves could unveil nonlinearities that are obscured by the use of G′ and G″, such as the phenomenon of strain stiffening.
Rapid three-dimensional magnetic resonance imaging of vocal tract shaping using compressed sensing.
Authors: Kim Yoon-Chul , Narayanan Shrikanth , Nayak Krishna S.
Published: October 2013

Conventional 3D magnetic resonance imaging (MRI) of vocal tract during sustained sound production takes prohibitively long and requires repetitions of the same articulation with pauses of the scan. This can produce image misregistration artifacts possibly due to different positioning of the jaw, tongue, and lips at each repetition. Within a scan time limit of 6–10 seconds, a duration practical for sustained sound production, it is desirable to accelerate high-resolution 3D imaging by undersampling 3D k-space. In this study, compressed sensing theory was adopted to achieve the acceleration by incoherent undersampling of 3D k-space and minimum L1-norm reconstruction. The increase in transform sparsity was exploited by constraining image phase in which rapid phase variation is expected in air-tissue boundaries due to large magnetic susceptibility difference. Vocal tract volume of interest was imaged during sustained sound production of English consonants /s/, /sh/, /r/, and /l/. Vocal tract area functions were measured using OsiriX software. The visualization of 3D tongue shape was demonstrated via image segmentation and volume rendering process. MR acquisition for each consonant took 6 sec without any repetitions of the articulation. The reconstruction of a whole 3D vocal tract was achievable with a 1.33×1.33×1.33 mm3 isotropic resolution. [Work supported by NIH.]
An analysis-by-synthesis approach to modeling real-time MRI articulatory data using the task dynamic application framework.
Authors: Bresch Erik , Goldstein Louis , Narayanan Shrikanth
Published: October 2013

We report on a method of modeling real-time MRI articulatory speech data using the Haskins task dynamic application (TaDA) framework. TaDA models speech using a set of discrete dynamical regimes that control the formation of vocal tract constrictions (gestures). An utterance can be specified by a gestural score: the pattern of activation of these regimes in time. Individual model articulator degrees of freedom are automatically coordinated according the concurrent demands of the unfolding constrictions. Our modeling procedure consists of two stages: (1) After determining the outline of the midsagittal upper airway, time series of constriction measurements are derived which allow the estimation of the subject-specific parameters relating the articulator and constriction domains. (2) Gradient descent is utilized to adjust the activation intervals of the gestural score generated by TaDA for that utterance so that the synthesized vocal tract constriction evolution matches the observed MRI time series. Additionally, information related to glottal control, which cannot be derived from the MR images, is extracted from the simultaneously recorded audio, and it is used to optimize the timing of glottal abduction gestures in the score. Adequacy of fit is evaluated at articulatory, constriction, and perceptual levels. [Work supported by NIH.]
Vowel recognition from articulatory position time-series data.
Authors: Wang Jun , Samal Ashok , Green Jordan , Carrell Tom
Published: October 2013

The goal of this project is to determine the accuracy and processing speed of different approaches for mapping time-varying articulatory positional data to vowels. Three widely used classifiers were compared on two datasets: one single speaker and one multiple speaker. The single-speaker dataset was acquired using the Articulograph AG500. The multiple-speaker dataset was obtained from seven speakers in the Xray Microbeam Speech Production Database (Westbury, 1994). The recognition rate for single speaker dataset (eight English vowels) ranged from 94.25% to 98.1%, and from 62.38% to 99.35% for the multiple-speaker dataset. For the single-speaker dataset, recognition accuracy was comparable across classifiers. For the multiple-speaker dataset, recognition accuracy was better for the Support Vector Machine and C4.5 than for the neural networks. The decision tree generated by C4.5 was consistent with articulatory features commonly used to descriptively distinguish vowels. Moreover, the Support Vector Machine and C4.5 performed much faster than did the neural network. The high recognition rates observed suggest that static vowels can be accurately recognized from articulatory position time-series data. The findings are intended to improve the accuracy and response time of a real-time articulatory-movement based speech synthesizer.
Korean articulatory speech synthesis using physical vocal tract model.
Authors: Luong Huynh V. , Kim Jong-Myon , Kim Cheol Hong
Published: October 2013

Artificial vocal tract models provide the support of learning a second language and the therapy of speech disorders. Moreover, phonetic education and research can benefit from articulatory speech synthesis. Articulatory speech synthesis models are constructed by the source-filter model of the human vocal tract. In this study, we generated a Korean articulatory speech synthesis model using Artisynth [Fels et al., ISSP, 419–426 (2006)], which is a 3-D biomechanical open-source simulation platform. As the origin of the Korean language, it has 10 basic vowel phonemes and 11 complicated vowels in which some vowels can be rounded and unrounded such as /eu/, /yeo/, /wae/, etc. To synthesize these specific vowels, we created a new physical vocal tract model, which interconnects to form a complete integrated biomechanical system. The created model efficiently supports recording the Korean vowel sounds and linguistic analysis based on the linear prediction model. As a result, parameters of the glottis and controllable vocal tract filter are automatically evaluated. The acoustic quality of the synthesizer for Korean vowels is comparable with that of the existing commercial speech synthesis systems such as concatenation synthesizers [Donovan (1996)] and [Hamza (2000)]. [Work supported by the MKE, Korea, under the ITRC supervised by IITA (IITA-2008-(C1090-0801-0039)).]
Acoustic wave scattering in turbulence and in internal waves.
Authors: Yamamoto Tokuo , Paris Clair , Badiey Mohsen
Published: October 2013

Analytical solutions of acoustic wave scattering have been obtained for turbulent currents and for shallow water internal waves. The scattering characteristics of the two are quit different. The most striking difference is that the maximum scattering is in only one direction by turbulence. Whereas there are two directions of maximum scattering in internal waves. In turbulence, acoustic waves scatter quite strongly while internal waves acoustic waves scatter very weakly. Therefore, turbulence changes acoustic wave (coherent) energy rapidly into (incoherent) scattered acoustic energy. The scattering of acoustic energy by internal waves is weak, on the order of 0.001 of that of turbulence. The theoretical results are verified with transmission loss measured in Kanmon Strait and at New Jersey Shelf with good agreements. [Work supported by ONR Code 322 OA.]
Resonant forward scattering of sound in the deep ocean by internal tides.
Authors: Rypina Irina I. , Udovydchenkov Ilya A. , Duda Timothy F. , Brown Michael G.
Published: October 2013

The importance of resonant forward scattering of sound by highly directional large amplitude nonlinear internal waves in shallow water environments has been well established. In contrast, most deep ocean environments are characterized by the presence of a sound speed perturbation (due mostly to internal waves) whose horizontal wave number spectrum is broad and approximately horizontally isotropic; under such conditions, the importance of resonant forward scattering is less clear. Exceptional deep ocean conditions are found in the vicinity of submarine ridges, which serve to generate internal tides that are both highly directional and have a narrow horizontal wave number spectrum. In this talk, ray, mode, and PE simulations are presented to explore the importance of resonant forward scattering by such structures under fairly realistic oceanographic conditions. [Work supported by ONR.]
The second order resolution operator of a nonlinear ocean acoustics inverse problem.
Authors: Odom Robert I. , Ganse Andrew A.
Published: October 2013

The resolution operator for a linear inverse problem indicates how much smearing exists in the map between the true model and the estimated model. The trace of the resolution operator provides an estimate of the number of model parameters model that are resolved. In a series representation of the resolution operator for a nonlinear problem, the higher-order terms indicates how much spurious nonlinear leakage there is from the true model to the estimated model. In previous work, the solution of a simple nonlinear ocean acoustic inverse problem as a perturbation series in the horizontal wavenumber was constructed, and the linear data kernels were presented. This linear problem permitted the quantification of the magnitude of the perturbation and indicated when nonlinear effects must be taken into consideration. In this extension of previous work, the second order resolution kernel is constructed, which describes how effectively nonlinear effects can be removed from the reconstructed model. [Work supported by ONR.]
How easy is it being green?
Authors: Ehnert Jesse J.
Published: October 2013

In 2007, the United States Green Building Council (USGBC) issued its Leadership in Energy and Environmental Design (LEED) for Schools Reference Guide defining requirements for certification which included classroom acoustical criteria. These criteria, which were based partially on the ANSI S12.60-2002 classroom acoustics standard, defined certification prerequisites (as well as additional credit requirements) in terms of three areas: reverberation time, sound isolation, and background noise level. In response to several issues related to compliance with these requirements, in 2008 the USGBC issued a Performance/Intent Equivalent Compliance Path (PIEACP) to provide alternate, and somewhat easier, means to meet LEED acoustic criteria. This presentation will weigh the potentially impractical aspects of the original guidelines and the possibly ineffective aspects of the PIEACP and will discuss the emergent areas of resistance on the part of designers and owners in relation to acoustical requirements in the context of several examples. It is the hope that properly addressing these points of resistance, and their inherent economic motivations may, perhaps, lead to a more reasonable, coherent, and enforceable set of criteria to achieve LEED certification.
Auditory research from the sleeper goby to zebrafish.
Authors: Lu Zhongmin
Published: October 2013

This presentation covers neural coding of acoustic particle motion by a hearing generalist (the sleeper goby, Dominator latifons) and research transition to a hearing specialist (the zebrafish, Danio rerio). Unlike sound pressure, particle motion, a component associated with sound pressure in any sound wave, provides the directional information about sound source. In recent years progress has been made in neural representation of acoustic particle motion by several hearing generalists that are primarily sensitive to the particle motion mode of sound. Here a review will be given on single-unit physiology of octavolateral afferent and efferent neurons as well as neurons in the descending octaval nucleus of the sleeper goby in response to linear acceleration that simulates underwater acoustic particle motion, providing insights into their functions. In the second half of the presentation, two preliminary projects in my lab will be introduced using the zebrafish that has become an increasingly important vertebrate model organism for biomedical research. The projects are development of the auditory function of zebrafish and alcohol effects on the octavolateral system of zebrafish. Advantages and disadvantages of different fish models will be discussed. [Work supported by NIH/NIDCD R01DC003275 and Gabelli Fellowship.]
Repetition is the branding iron of knowledge: Lessons from the mulitple origins of enhanced hearing.
Authors: Braun Christopher B.
Published: October 2013

Enhanced hearing, the ability to detect minute fluctuations in ambient pressure, has evolved independently or nearly so within every major group of vertebrates. Within Teleost fishes, enhanced hearing has evolved perhaps as many as 20 times. Within one subset of cichlid fishes, the Malagasy and south Asian Etroplinae + Ptychochrominae, several lineages appear to have independently evolved morphological specializations that might enhance hearing. There are approximately 25 species of cichlids on Madagascar and all are narrowly endemic with well-defined habitats ranging from shallow floodplain lakes to rheophilic habitats. The gas bladders of individual species range from unspecialized (Katria katria) to highly modified (Paretroplus sp). All species of Paretroplus possess paired intracranial auditory bulla, but individual species vary in the degree of gas bladder modification (e.g., tunic stiffness, diverticula structure). This diversity presents a unique opportunity to explore the relationships among habitat noise and hydrodynamics, morphological specializations, and hearing ability within a specific phylogenetic hypothesis. This talk will present the history of hearing evolution within Malagasy cichlids, covering ecological, morphological, and functional aspects. The multiple independent origins of hearing will be emphasized as replicates of evolutionary experiments. Such replication highlights the commonalities behind the evolution of hearing in all vertebrates.
Investigation of the impact of water column variability on acoustic inversions in a shallow water ocean.
Authors: Lin Ying-Tsong , Lynch James F. , Duda Timothy F.
Published: October 2013

Underwater sound propagation in a rapidly evolving shallow-water ocean has high temporal and spatial variability. To ensure the performance of acoustic inversion techniques to locate a sound source or estimate the sea-bottom parameters, it is necessary to take into account the water column variability, which can be done by introducing the empirical orthogonal functions (EOFs), which describe the water column variability, into the environmental model used for the inversions. However, in a range-dependent and time varying ocean, one needs to regularly update the EOFs according to the scales of environmental, spatial, and temporal coherence, or the EOFs may not be the most efficient and optimal vector bases to decompose the dynamic ocean field. In this paper, the environmental data collected during the New Jersey Shallow Water 2006 (SW06) experiment are analyzed to check the environmental coherence scales in the experimental site. The analysis results provide a guideline as to when and where one should update the EOF bases. The observation of the SW06 acoustic signal coherence is reported and correlated to the environmental variability. Finally, acoustic inversions using the SW06 data are performed, and the effects of using insufficient water-column EOFs are investigated.
Extracting waveguide parameters from the coherent field measured on a synthetic aperture horizontal array.
Authors: Becker Kyle M
Published: October 2013

For a time-harmonic source in a stratified waveguide, the acoustic field can be approximated by a coherent sum of modes propagating in range. In range-dependent waveguides, the phase contribution from mode n is the product of a range-dependent wave number kn(r) and range. At any given range, kn is dependent on water depth and the depth-dependent geoacoustic parameters of both the water column and the seabed. To exploit these relationships, inversion algorithms have been developed for estimating range-dependent seabed properties from the acoustic field measured on synthetic aperture horizontal arrays. These methods are based on inferring information about the waveguide environment by extracting information contained in the phase of the acoustic signal as a function of range. In this talk we examine the individual contributions to the total phase from each of the propagating modes based on changes in depth, sediment sound speed, and water column properties. Sensitivity of individual modes to each of these changes will be examined along with their contribution to the total field. Issues associated with estimating modal content from field data and their use in inverse problems will then be discussed.
The evolution of vertical spatial coherence with range from source.
Authors: Dahl Peter H. , Tang Dajun , Choi Jee Woong
Published: October 2013

Vertical spatial coherence for shallow water propagation at frequencies 1–10 kHz is studied as function of range (50 to 5000 m), as part of the Shallow-Water 2006 program that took place off the coast of New Jersey in August 2006 in waters 80 m deep. An acoustic source was deployed from the R/V Knorr at depths 30 and 40 m and signals were recorded on a moored receiving system consisting of two 1.4 m long vertical line arrays (VLA) centered at depths 25 and 50 m. At all ranges, spatial coherence, Γ (normalized spatial correlation), is locally stationary and depends on element vertical separation d up to the maximum kd (59) afforded by the VLA, where k is acoustic wave number. For range normalized by depth, r*, less than about 10, Γ is oscillatory, with non-zero imaginary part, reflecting the inclusion of multipaths for which no single path dominates. For r* greater than 10, Γ tends to exhibit a monotonic decay with kd and the imaginary part vanishes reflecting symmetry about 0 deg vertical arrival angle. The coherence also increases with r* reflecting the change in modal structure. [Research supported by ONR Ocean Acoustics.]
On the use of coded excitation and pulse compression to reduce estimate error of average scatterer diameters obtained from ultrasonic backscatter.
Authors: Sanchez Jose R. , Pocci Darren , Oelze Michael L.
Published: October 2013

A technique that extends the tradeoff of variance of average scatterer diameter (ASD) estimates and the spatial resolution in quantitative ultrasound (QUS) images is proposed. Resolution enhancement compression (REC), a coded excitation and pulse compression technique, was used to enhance the −6-dB bandwidth of an ultrasonic imaging system. The objective of this study was to combine REC with QUS (REC-QUS), and evaluate and compare improvements in ASD estimates obtained using the REC technique to conventional pulsing (CP) methods. Simulations and experimental measurements were conducted with a 10 MHz weakly focused (f/4) single-element transducer (−6-dB bandwidth of 80%). Using REC, the −6-dB bandwidth was enhanced to 152%. In simulations, a homogeneous phantom with scatterers 50 μm in diam was evaluated. In experimental measurements, a tissue-mimicking phantom that contained glass spheres with scatterer diam that range from 45 to 53 μm was evaluated. Estimates of ASD were obtained by comparing the normalized backscattered power spectra to theory. Simulation results indicate that for a constant variance, a reduction in region-of-interest size from 15 CP pulse lengths to 1.5 CP pulse lengths was achieved by using REC-QUS. In experimental measurements, the estimate variance decreased by 88% by using REC-QUS over conventional QUS. [Work supported by NIH-R21-EB006741.]
Time-reversal Rayleigh wave for soft solid characterization.
Authors: Javier Brum , Nicolas Benech , Carlos Negreira , Stefan Catheline , Thomas Gallot
Published: October 2013

In this work the shear elasticity of soft solids is measured from the surface wave speed estimation. An external source creates mechanical waves in the audible frequency range. Surface waves are detected using acoustic sensors. The surface wave speed estimation is extracted from the complex reverberated elastic field through a time-reversal analysis. These quantitative measurements in a hard and a soft gelatin-based phantom are validated by independent transient elastography estimations. In contrast with other quantitative elasticity assessment methods, one advantage of the present approach is that it is based on a low cost sound technology. Moreover, the robust and simple experiments performed in cheese and soft phantoms, allows thinking of applications in food industry and medicine.
Acoustic and vibrometry analysis of beating in a large Balinese gamelan gong.
Authors: Krueger David W. , Gee Kent L. , Grimshaw Jeremy , Manuel Dorothy , Jones Molly E.
Published: October 2013

A large Balinese gamelan gong, the gong ageng wadon, is similar to other Indonesian gongs in that it is tonal. A previously undocumented phenomenon is the fact that this gong produces distinct beating, which is essential to Balinese gamelan music. In this study of Brigham Young University’s gong ageng wadon, acoustical and vibrometry measurements were performed to analyze the source of the beating. Scanning laser Doppler vibrometer results show a beat frequency of about 3 Hz is produced near 150 Hz by closely spaced structural modes. A slightly slower beat frequency (around 2.5 Hz) is also produced at about 120 Hz. The difference in this case is that there is only one structural mode measured near this frequency. It appears that the acoustic radiation from this mode beats with a harmonic of the radiation from a lower structural mode and that this harmonic is caused by nonlinear acoustical phenomena.
Importance of visual cues in networked music performances.
Authors: Braasch Jonas
Published: October 2013

Although music is predominantly an acoustic event, the importance of visual cues should not be underestimated. In this paper, a number of observations will be presented that were derived both from laboratory experiments and ongoing music collaborations over the Internet. Different requirements exist for networked music performances than for telematic speech conferences for which most Internet-based telecommunication systems have been developed. For example, audio/visual synchronicity is essential for speech applications, but it was often found advantageous to run the audio ahead of the video in networked music performances to minimize the audio delay, which needs to be below a critical value if the remote ensembles perform together rhythmically. Other aspects of speech and music applications are very similar, for example, the need to exchange documents, which are in the case of music predominantly music scores. In the common telepresence approach, it is typically asked how realistic the recreated environment has to be for satisfying results. In this paper, an alternative, more abstract approach based on virtual functionality will be discussed that also includes the integration of music scores into the virtual environment. [Work supported by NSF Grant 0757454.]
Marine mammal noise exposure criteria: Initial scientific recommendations.
Authors: Southall Brandon L. , Bowles Ann E. , Ellison William T. , Finneran James J. , Gentry Roger L. , Greene Charles R. , Kastak David , Ketten Darlene R. , Miller James H. , Nachtigall Paul E. , Richardson W. John , Thomas Jeanette A. , Tyack Peter L.
Published: October 2013

An expert panel reviewed the expanding literature on marine mammal (cetacean and pinniped) auditory and behavioral responses to sound exposure to develop comprehensive, scientifically based noise exposure criteria [Aquatic Mammals 33(4)]. They used precautionary extrapolation procedures to predict exposure levels above which adverse effects (both physical and behavioral) could be expected. Due to the paucity of data on long-term exposures, criteria were developed for single exposure events only. Marine mammals were broken into functional hearing groups. Exposure types were lumped into three broad classes (single pulses, multiple pulses, and nonpulses). Levels estimated to induce permanent noise-induced hearing loss were determined for each of 15 sound type/animal group combinations. For example, injury criteria for pinnipeds in water exposed to multiple pulses were 186 dB re 1 μPa2 -s (weighted SEL) and 218 dBpk re 1 μPa (unweighted peak SPL). Discrete behavioral disturbance thresholds could only be determined for exposure to single pulses. For other exposures, available data on behavioral responses were ranked by severity and significance. This severity scaling and the resulting conclusions will be described. New research required to improve criteria and to assess cumulative and ecosystem-level effects will also be considered, along with current policy and/or regulatory applications.
Role of the National Marine Fisheries Service in underwater acoustics: Integration of science and policy.
Authors: Scholik-Schlomer Amy R. , Guan Shane , Harrison Jolie
Published: October 2013

The National Marine Fisheries Service, Office of Protected Resources (NMFS OPR) is responsible for protecting marine mammals and other endangered marine species and works to conserve and recover these species under the Marine Mammal Protection Act and Endangered Species Act. Accurately assessing the impacts of anthropogenic underwater noise on the marine environment and implementing appropriate measures to reduce such impacts is one of its primary focuses. To do this successfully requires the integration of science with policy. This integration combines a complex set of factors. NMFS OPR has jurisdictions over a variety of marine species, considers a wide range of potential impacts, and regards a diverse assortment sound sources. Additionally, it works collaboratively with other federal, state, and local government agencies, academia, nongovernmental organizations, and industry, as well as solicits public input on the actions it regulates. NMFS OPR uses and relies on scientific data to make informed decisions on numerous issues relating to anthropogenic underwater noise, including developing appropriate acoustic thresholds for assessing impacts and best protecting marine species via the establishment of practicable mitigation and monitoring protocols. To most effectively achieve these goals requires continual interaction with and input from those in the scientific community.
Methods for computing the impact of sonar on the marine environment.
Authors: Siderius Martin , Houser Dorian , Hernandez Daniel , Porter Michael
Published: October 2013

Federal agencies are required to estimate the impact to the environment resulting from major federal actions. The U.S. Navy is required to prepare environmental impact statements (EISs) for a number of its training ranges, in part, due to the controversial nature of the sonar systems used at these sites. Over the past several years these EISs have been prepared by both government agencies and by contractors. This multi-institution approach has led to different methodologies being used to estimate impacts on marine mammals. Different impact estimates and confusion as to the real risk posed by a particular sonar system has resulted. As part of the Office of Naval Research program on the effects of sound on the marine environment (ESME), we have been assembling state-of-the-art modeling software to provide the Navy and the Public the best risk assessment tools currently available. One of the challenges to this effort is determining which approaches provide the best estimates of risk and which are practical to implement. Related to this is the development of an objective set of metrics to make such evaluations. In this presentation we will describe the risk modeling methodologies and the metrics being used for analysis in the ESME model.
Ambient noise properties in a region of Puget Sound.
Authors: Dall’Osto David , Dahl Peter H.
Published: October 2013

Ambient noise data collected during August 2007 at a site near the Smith Island Marine Sanctuary in North Puget Sound, Washington, depth 100 m, is discussed. This marine sanctuary is representative of a marine mammal habitat, where adverse impacts of noise are of concern. Properties of the ambient noise environment are inspected relating to frequency content and vertical directionality. Wind speed and wave spectral data for correlations were provided by the Smith Island weather station and a nearby NOAA buoy. Two co-located systems were used to estimate spectral levels of the ambient noise environment. The directional information is provided by one of these systems consisting of a pair of omni-directional elements vertically separated by 15 cm. Candidate models for noise directionality are tested against the array gain for this simple system evaluated as a function of frequency, giving an approximate picture of the noise density as a function of vertical arrival angle at particular frequencies of interest. [Research supported by Washington Sea Grant.]
Measurements of industrial noise and vibration in artificial polar bear (Ursus maritimus) dens, Flaxman Island, Alaska.
Authors: MacGillivray Alexander O. , Hannay David E. , Perham Craig J.
Published: October 2013

Noise and ground vibration generated by environmental remediation activities were measured in man-made polar bear (Ursus maritimus) dens at Flaxman Island, Alaska in Mar. 2002. The remediation activities involved use of heavy excavation equipment, ground vehicles, and blasting. Comparison of sound levels measured inside and outside the dens permitted estimation of the sound-insulating properties of the dens. Vibration data were acquired from sensors placed in the tundra and in the snow of the den floors. Measurements of noise and vibration were made for the following vehicles: front-end loader, trimmer, gravel hauler, fuel truck, pickup truck, Hägglunds tracked vehicle, and a Tucker Sno-Cat. A single 8.7 kg blast event at 19 m underground, which was used to cut a well pipe, was recorded in the dens at distances from 500 to 1300 m. Additional noise and ground vibration data were obtained for Bell 212 and Bell 206 helicopters performing maneuvers above the dens. The man-made dens were found to have good sound-insulating properties. Sound levels inside the dens were lower than directly outside the dens by 25 dB at 50 Hz, and by 40 dB at 1000 Hz.
Mediterranean fin whale migration movements altered by seismic exploration noise.
Authors: Castellote Manuel , Clark Christopher W. , Colmenares Fernando , Esteban José Antonio
Published: October 2013

Seafloor recorders were deployed along the Spanish Mediterranean coast during 2006–2009 to further contribute to the little knowledge regarding Mediterranean fin whale (Balaenoptera physalus) movement patterns. Typical long patterned sequences of 20-Hz pulses were identified in different periods. Detection results suggest that at least part of the Mediterranean fin whales aggregating in the Ligurian-Corsican-Provençal basin during summer migrate through French and Spanish waters toward southern Mediterranean regions, including the south of Spain. Continuous airgun explosions from a seismic survey were detected during 8–17th December 2006 in the south of Spain. A concurrent fin whale reaction in acoustic behaviour was documented: All singing whales moved away from the airgun area and out of the detection area during the following 20 days, even after the airgun noise ceased on the tenth day, and remained weak after the 20-day period. Twenty-hertz pulse bearings for this period revealed that calling whales were moving through the sensors detection area and not that whale acoustic behaviour was reduced by the seismic activity. We therefore conclude that the seismic airgun activity caused fin whales to avoid their potential winter ground for a period of time that extended well beyond the duration of the seismic airgun array activity.
Effect of temporal uncertainty on psychometric functions for increment detection.
Authors: Jesteadt Walt , Patra Harisadhan , Neff Donna L.
Published: October 2013

Increased temporal uncertainty might be expected to produce increased internal noise, resulting in poorer detection and shallower psychometric functions. An alternative model in the literature predicts steeper psychometric functions with increased uncertainty. As a test of these two alternatives, detection of a 20-ms intensity increment was assessed for eight subjects in a two-interval, forced-choice adaptive procedure where the increment was presented 100, 150, 200, 250, or 300 ms after the onset of a 400-ms, 4-kHz tone presented at 70 dB SPL. In one condition, the temporal position varied randomly from trial to trial. In the other, the temporal position was fixed for an entire 50-trial block. Detection thresholds were higher and psychometric functions obtained by analyzing the trial-by-trial data from the adaptive tracks were shallower in the higher temporal uncertainty condition. Thresholds in both conditions were higher for temporal positions more distant from the center of the 400-ms tone. Results support a model in which temporal uncertainty contributes to internal noise resulting in shallower psychometric functions. [Work supported by R01 DC006648 and T32 DC000013.]
Increment discrimination.
Authors: Jesteadt Walt , Patra Harisadhan , Messersmith Jessica
Published: October 2013

Subjects rely on different information in an intensity-discrimination task, where the two sounds to be compared differ only in intensity, than in increment detection, where one of the two sounds contains a brief increment in intensity in a longer duration tone. To explore the transition from one task to the other, ten subjects were tested in a two-interval forced choice discrimination task in which both intervals contained 50-ms increments in a 400-ms, 500-Hz tone and subjects were asked to vote for the interval with the larger increment. The size of this second increment was adapted to obtain an estimate of threshold. Increment-discrimination thresholds were better than increment-detection thresholds when the standard increment was less than or equal to detection threshold. Increment-discrimination thresholds became poorer for standard increments in the range from 1.5 to 12 dB above the level of the longer duration tone. For standard increments above that level, increment discrimination approximated intensity discrimination. Slopes of psychometric functions became shallower as the standard increment increased, consistent with a transition from an increment-detection to an intensity-discrimination decision process. [Work supported by R01 DC006648 and T32 DC000013.]
Randomized phase effects in amplitude modulated/quasi-frequency modulated discrimination.
Authors: Tabuchi Hisaaki , Borucki Ewa , Berg Bruce G.
Published: October 2013

This study investigated the bandwidth of phase sensitivity (i.e., discrimination of waveform envelopes). Subjects discriminated amplitude modulated (AM) tones, and quasi-frequency modulated (QFM) tones in a 2IFC. An adaptive threshold procedure was used to estimate modulation depth m needed to make the discrimination as a function of carrier and modulation frequency. Nonmonotonic threshold functions were often observed at higher modulation frequencies. The effect is discussed in terms of two potential cues: (1) waveform envelope, (2) cubic distortion products. In order to degrade the information obtained from the distortion products, the phase for the carrier frequency was randomly sampled with a range of, Δθ=π/3. The randomized phase diminishes the nonmonotonicities of the threshold functions. Final results show that bandwidths of maximum sensitivity are not proportional to carrier frequencies. There are also noticeable individual differences in both the effects of the distortion products and the maximum bandwidths of sensitivity. [Work supported by NSF BCS-07464003.]