bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of boats on the vocal behavior of humpback whales off Brazil
Authors: Sousa-Lima Renata S. , Morete Maria E. , Fortes Roberto C. , Freitas Ana C. , Engel Marcia H.
Published: October 2013

Experiments were performed to evaluate the impact of boat approaches on the vocal behavior of humpback whales that breed around the Abrolhos archipelago off the Brazilian coast. Vocalizing whales were located by monitoring the amplitude of each individual’s sounds. Silent approaches to focal singers were performed using a small zodiac with an improvised sail. Songs were recorded with one hydrophone connected to a portable DAT recorder before and during the approach of a vessel. Spectrograms were correlated to each whale’s activity and position with respect to the vessel. Differences in song variables of two individuals were tested when the motor was ON and OFF. Both whales sang shorter versions of their songs when exposed to engine noise. No alteration in mean phrase duration was detected, but the number of phrases in each theme decreased. Three individuals interrupted their songs after a motor boat switched gears within 300 m, and resumed singing when the engine was returned to neutral. The limited number of observables calls for further investigation to evaluate the consequences of boat impact. More reliable information will allow regulation to achieve sustainable tourism activity in the area. [Work supported by FBPN, MacArthur Foundation, Society for Marine Mammalogy, Instituto Baleia Jubarte.]
Effect of boat traffic on the vocal and surfacing behavior of river dolphins: A key for abundance estimation methods
Authors: Diazgranados Maria Claudia , Meja Paola , Acosta Adriana
Published: October 2013

To evaluate the effect of boat traffic on vocal and surfacing behavior of river dolphins, Inia geoffrensis and Sotalia fluviatilis, field recordings and scanners were carried out in the Amazon River during 2001. Changes on surface dolphin activities and vocalization rates were analyzed. Twenty complete slot interferences between boats and dolphin vocal behavior were selected from 2400 min of total recording. Significant differences between signal types (squeals for Inia and whistles for Sotalia) between pre-exposure, exposure, and post-exposure to the interference were found, for both Inia and Sotalia species. Six hundred scanners were conducted from a 6-m-high base observation platform. Interferences with pre-exposure, exposure, and post-exposure times were selected with only one boat crossing the dolphin area. Significant differences in frequency, type of event, and immediate response were observed for both Inia and Sotalia species, especially when a speedboat was crossing the area at high speed. This information shows that boat traffic did affect vocal and surface behavior of river dolphin species inhabiting the Amazon River in Colombia, and that abundance estimations using boat transect along the river may change depending upon the type and speed of the vessel used.
Fish, mollusks and other sea animals’ use of sound, and the impact of anthropogenic noise in the marine acoustic environment
Authors: Stocker Michael
Published: October 2013

Many marine animals use sound and acoustic energy sensors to adapt to their environment. Most biological studies closely examine a particular species’ relationship to a specific stimulus. This report examines the fields of research on marine biological adaptations to sound since 1950, assembling an overview of the biological importance of sound in the ocean. It also examines the various sources of anthropogenic noise in the sea with a focus on the potential impacts of that noise on the marine acoustic environment. [Work sponsored by Earth Island Institute.]
Variation of the ‘‘Black Hole’’ phenomenon with speed and stroke rate
Authors: Paeng Dong-Guk , Shung K. Kirk
Published: October 2013

The Black Hole (BH) phenomenon, a central hypoechoic hole surrounded by a hyperechoic zone, has been observed and investigated only under steady flow. The phenomenon was recently observed under pulsatile flow, but its variation during a cycle has never been reported yet. In order to better understand the BH phenomenon and its variation, a GE LOGIQ 700 Expert system was used to collect B mode images from porcine blood in a rigid tube (ID: 9.5 mm). The BH became weaker or disappeared during the systole in terms of contrast and size. The variation of the BH over a cycle was investigated with the peak speed levels (10–25 cm/s), stroke rates (20, 40, 60 beats/min), mean speed levels (10, 20 cm/s), and hematocrits (12%–46%). Under steady flow, the BH phenomenon started to appear at an asymmetrical radial position at very low speeds when speed was increased. The BH shifted to the center of the tube at higher speeds and finally disappeared at ∼100 cm/s. However, the asymmetrical position at lower speeds was not observed when speed was decreased. The variation in the BH is presumably due to the red cell aggregation, which is affected by the shear rate and acceleration during a pulsatile cycle.
Time reversal focusing through a human skull optimized by skull surface detection algorithm
Authors: Aubry Jean-Francois , Cassereau Didier , Fink Mathias
Published: October 2013

High-intensity focused ultrasounds are mainly envisioned to cure liver and prostate cancer. In order to cure brain tumors, it has been shown that time reversal coupled with amplitude compensation is an interesting technique to correct the aberrations induced by a human skull. This focusing technique should be improved by compensating the amplitude at the exact location of the skull. To measure the geometrical shape of the skull, two different techniques are investigated and compared in terms of precision and duration of the measurement. The first method is based on the measurement of the propagation time from the array to the skull and back of pulsed signals emitted and received by each pair of transducers of an echographic array of 128 transducers. For each pair, the reflection point on the skull is located on an ellipse whose centers correspond to the positions of the emitting and receiving elements. The envelope of the complete set of ellipses is then extracted, giving the shape of the skull. This technique is compared to echographic imaging of the skull using the same array. Comparisons between these techniques will be presented using the Phased Array Simulation software and the corresponding experimental focusing.
Predicting habituation/adaptation to aircraft noise
Authors: Hatfield Julie , Job RF Soames , Morrell Stephen , Carter Norman L. , Peploe Peter , Taylor Richard
Published: October 2013

Whether or not people habituate and/or adapt to a negative soundscape remains a contentious issue. The Sydney Airport Health Study has involved interviews with residents before, soon after, and several years after the runways were reconfigured. Noise increased in some low-noise areas and decreased in some high-noise areas (while other areas remained highly exposed and unchanged, or minimally exposed to aircraft noise). Of the pre-reconfiguration sample, 23.6% reported getting used to the noise. This paper examines the factors which predict who will get used to the noise and who will not, by regression against a number of predictors: noise exposure, sensitivity, attitude, personality, age, gender. The post-reconfiguration studies also allow examination of the speed with which reaction changes with changed exposure, and the factors which predict changes in reaction. Underlying mechanisms other than adaptation and habituation are considered.
Resonance acoustic spectroscopy of lossy materials
Authors: Ostrovsky Lev A. , Lebedev Andrey V. , Soustova Irina A. , Sutin Alexander M. , Johnson Paul A.
Published: October 2013

Resonance acoustic spectroscopy (RAS) is known as an efficient tool for determining the elastic and dissipative parameters of materials. However, its use for diagnostics of a variety of materials with a low quality factor (including materials with defects) is often impeded by overlapping of resonance responses at different modes. Here, a method of processing experimental data is suggested which enables one to determine resonance frequencies and Q-factors in cases of broad and overlapping resonances. In experiments, both undamaged and cracked samples were studied. A swept-frequency excitation was used for polycarbonate samples, whereas an impulse method with impact excitation was used for concrete samples. Signal processing was performed with the use of the suggested algorithm. In particular, the decrease of the Q-factor and splitting of resonance frequencies due to crack formation were registered. This method, which demonstrates a high efficiency even at a significant resonance overlapping, can be used for nondestructive testing of a broad class of materials.
Single-transducer continuous-wave noninvasive ultrasonic characterization of fluids
Authors: Kwiatkowski Christopher S. , Sinha Dipen N.
Published: October 2013

Ultrasonic fluid characterization studies that utilize a continuous wave (cw) frequency-sweep technique typically employ a source transducer and a receiver transducer. This arrangement can lead to problems such as transducer misalignment, diffraction effects, and mechanical and electrical coupling. In contrast, the traditional tone-burst technique that uses a single transducer for both transmit and receive functions can alleviate some of the problems associated with the cw technique. However, the frequency-sweep technique allows for much higher signal-to-noise ratios and observation of relevant phenomena that occur early in time that can be missed by the tone-burst technique. Reflection-mode single-transducer techniques have been developed in the past, but these usually require high-precision bridge circuits and exact balancing circuitry to provide satisfactory results over a narrow frequency range. Due to impedance-matching issues, the dynamic range of such measurements can be problematic. We describe a single-transducer cw frequency-sweep technique that takes advantage of the high dynamic range of current commerically available instrumentation, which allows noninvasive fluid characterization. The advantages of using such a device, as well as experimental results and a theoretical model, will be presented. Comparisons with two transducer designs will also be discussed.
Visual correlates to focal accent and their relation to the fundamental frequency contour
Authors: Sangari Sonia
Published: October 2013

Focal accent in speech is signaled by a fundamental frequency manifestation and by prolonged segment duration in connection with the manifestation. In the present investigation, the visual correlates to focal accent in read speech are studied and a computational model is hypothesized. The acoustics is synchronized with the head movements in order to relate the movements to the manifestations of the fundamental frequency contour. It is found that head movements are correlated to the primary stressed syllable of the word-carrying focal accent. The obtained data show that it is possible to model the movements by means of a second-order linear system.
The effects of variations in voice type on the acquisition of second language vocabularly
Authors: Barcroft Joe , Sommers Mitchell S.
Published: October 2013

The present study was designed to examine whether variations in voice type affect second language (L2) vocabulary acquisition relative to conditions with constant acoustic-phonetic mappings. Listeners with no previous formal training in Spanish attempted to learn 24 Spanish words in one of three conditions: (1) No Variability: all items were presented in a neutral or conversational voice type; (2) Moderate Variability: items were presented in three different voice types (neutral, nasal, and time-expanded); and (3) High Variability: items were presented in six different voice types (the three voice types used in the moderate variability condition along with whispered, excited, and pitch-shifted). All stimuli were recorded by a native speaker of Spanish and pilot testing indicated nearly perfect identification of the test stimuli by native speakers. Accuracy and latency measures were obtained for both production and translation of L2 vocabulary. No significant differences between the three learning conditions were observed, indicating that acoustic variation had little effect on the obtained measures of L2 vocabulary acquisition. The results are discussed from modular and interactive perspectives, focusing on how diverse acoustic examples of words may become normalized during second language acquisition.
On the origins and scope on final lowering
Authors: Arvaniti Amalia , Taylor Lara
Published: October 2013

This experiment examines final lowering, the lower than expected scaling of the last pitch accent in downstepping word lists. In word lists of four or five items two parameters were manipulated. First the number of unaccented syllables between accents was either constantly two (‘‘LIma beans, GREEN beans and SOY beans’’); alternatively, the presence of ‘‘and’’ resulted in an extra syllable between the penultimate and final accent (‘‘LIma beans, NAvy beans and SOY beans’’). Second, the number of unaccented syllables after the final accent was either one (‘‘SOY beans’’) or three (‘‘HAricot beans’’). The results showed evidence of final lowering, in that the final accent in four word lists was lower than the fourth accent in five word lists, but the presence of ‘‘and’’ did not produce extra lowering of the final peak, suggesting that final lowering is an independent phenomenon, not an epiphenomenon of declination (contra-Grabe). On the other hand, the final accent was scaled higher when the number of unaccented syllables following it was larger. This suggests that final lowering is not under phonological control but a physiological phenomenon, since it does not target the last accent but a fixed time interval before the end of the utterance.
A simple hydrodynamic semi-continuum model of vocal-fold motion
Authors: LaMar Drew , Qi Yingyong , Xin Jack
Published: October 2013

Vocal-fold (VF) motion is a fundamental process in voice production, and is also a challenging problem for direct numerical computation because the VF dynamics depends on nonlinear coupling of airflow with the response of VFs, which undergo opening and closing, and induce internal flow variation. A traditional modeling approach makes use of Bernoulli’s law to treat the airflow, which is known to be inaccurate during VF opening. A new hydrodynamic semi-continuum system for VF motion is formulated. The airflow is modeled by a quasi-one-dimensional continuum aerodynamic system, and the VF by a classical lumped two-mass system. The reduced flow system contains the Bernoulli’s law as a special case, and is derivable from the two-dimensional compressible Navier–Stokes equations. Since no (quasi-)steady approximation is made, transients and rapid changes of solutions are captured, e.g. the double pressure peaks at opening and closing stages of VF motion in agreement with experimental data. It is demonstrated numerically, via a split-time finite difference method, that the system is simple, robust, and models in vivo VF airflows and oscillations efficiently. [Work partially supported by NSF and ARO.]
Analysis of vocal fold vibration on prosodic events by high speed digital imaging systems
Authors: Kumada Masanobu , Kobayashi Noriko , Hirose Hajime , Tayama Niro , Imagawa Hiroshi , Sakakibara Ken-Ichi , Nito Takaharu , Wada Mamiko , Kakurai Shin’ichi , Kumada Chieko , Niimi Seiji
Published: October 2013

A physiological study of prosody is indispensable in terms of the physiological interest as well as of the evaluation and treatment for pathological cases of prosody. We have already reported the study with our high speed digital imaging system [143rd ASA Meeting, 2002] that two major categories (Categories A and B) were found in the ways of changing of vocal fold vibrations at the register change in sustained phonations. In Category A, changes were very smooth in terms of the vibration of the vocal fold vibration. In Category B, changes were not so smooth with some additional events at the register change, such as the anterior–posterior phase difference of the vibration, the abduction of the vocal folds, or the interruption of the phonation. The number of the subtypes for Category B was thought to increase if more subjects with more range of variety are analyzed. In this study, the changes of vocal fold vibration on prosodic events in free talk as the pitch changes were analyzed, using two types of high speed digital imaging system: the one with recording time of two seconds at a rate of 4,500 images of ∼256 pixels per second; the other with a recording time of seven seconds at the same rate with the same spacial resolution as the former. This study showed that high speed digital imaging systems were very powerful tools for the study of prosody.
Examination of models of mucosal wave propagation
Authors: Berry David A.
Published: October 2013

Over the years, many models have been proposed to capture mucosal wave propagation along the medial surface of the vocal folds. However, historically, little quantitative data have existed with which to evaluate such models. Indeed, standard methods of laryngeal examination have imaged the medial surface vibrations of the vocal folds very poorly. However, new methods of imaging the medial surface dynamics of the vocal folds have recently been reported [D. A. Berry, D. W. Montequin, and N. Tayama, J. Acoust. Soc. Am. 110, 2539–2547 (2001)]. These data are used to evaluate a variety of models of mucosal wave propagation. [Work supported by NIDCD Grant No. R01 DC03072.]
Correlation of acoustic scattering variables and physical oceanographic parameter time series in the 2001 ASIAEX South China Sea experiment
Authors: Duda T. F. , Lynch J. F. , Newhall A. E. , Chiu C.-S. , Ramp S. R. , Chen C.-F.
Published: October 2013

During May 2001, 210- to 550-Hz signals were transmitted from five moored sources to moored array receivers in 120-m water on the continental slope in the northern portion of the South China Sea. Transmissions were made for three weeks over distances of 20 km along slope and 32 km across slope, in an area with highly irregular topography. The oceanography in the transmission area exhibited large variations, with the largest being due to the nonlinear internal wave field. In this study, we examine the cross-correlation of the measured oceanographic variability with the measured acoustic variability, in particular with the travel time wander and spread and the acoustic intensity. We emphasize the variability within specific oceanographic bands: subtidal, tidal, and high frequency. [Research sponsored by ONR.]
Chaos and wave propagation regimes
Authors: Colosi John
Published: October 2013

Ray chaos theory and parabolic equation numerical modeling were two thrusts of Fred Tappert’s research that were perpetually in tension. Fred was interested in the problem of identifying wave propagation regimes, most notably the strong focusing caustic regime and its evolution into the saturation regime. On the one hand, chaos theory held the seed of the complexity Fred believed existed in ocean acoustic wavefields; on the other hand ocean acoustic ray chaos theory (which Fred helped to pioneer) was a disdainful approximation to the full wave treatments offered by parabolic equation calculations. Fred was convinced that the saturation limit could not be obtained using ray theory and therefore he examined a new field of inquiry: a blend of chaotic ray insight and full wave dynamics called wave chaos. This talk will discuss some of Fred’s insights on this topic and how they relate to observations from basin scale acoustic transmissions.
Dozier–Tappert theory for long-range propagation
Authors: Henyey Frank S. , Wolfson Michael A.
Published: October 2013

Among Fred Tappert’s contributions to ocean acoustics is the mode transport equation in the paper he wrote with Dozier. In light of the results reported by Wolfson (this session), we need to have a theoretical approach other than chaotic rays for long-range propagation experiments; mode transport is a promising candidate. The principal assumptions made by Dozier and Tappert are the Markov approximation and the assumption that cross-mode coherence is small. Although eminently reasonable at the time they wrote their paper, the latter approximation must be questioned due to newer data and simulations. Deep arrivals constitute a phenomenon directly predictable from mode transport equations that extend that of Dozier and Tappert by including travel time information.
Statistics of normal-mode amplitudes in shallow water
Authors: Rouseff Daniel
Published: October 2013

Dozier and Tappert published a statistical theory of acoustic propagation in a random ocean [J. Acoust. Soc. Am. 63, 353–365 (1978)]. Their theory predicts the statistical moments of the acoustic mode amplitudes. The acoustic modes are coupled by random variability in the water column. Creamer extended the theory to include bottom loss, an important factor in shallow-water applications [J. Acoust. Soc. Am. 99, 2825–2838 (1996)]. In the present paper, the extended theory is applied to propagation through a realistic shallow-water internal wave model. An efficient computational algorithm is developed that makes practical the theory’s application to observed sound speed and buoyancy profiles. Model parameters such as bottom loss and internal-wave strength can be varied with minimal computational cost. Numerical results are presented that demonstrate the competing effects of modal attenuation and mode coupling. [Work supported by ONR.]
A comparison of background noise levels and reverberation times measured in unoccupied elementary classrooms
Authors: Godfrey Richard D.
Published: October 2013

The key performance criteria listed in ANSI S12.60-2002, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools, are that the maximum background noise is limited 35 dBA, and that the maximum reverberation time is limited to 0.6 seconds in the most common classroom size. Limits on sound transmission properties of the room envelope are also made. If these performance criteria are met, each student, no matter where he or she sits in the classroom, will be in an environment that affords adequate speech intelligibility, i.e., an adequate opportunity to understand the teacher’s words correctly. During the standard development process, the author had the opportunity to work with his colleges at The Ohio State University. The OSU group made measures in 34 classrooms in the Columbus area (inter-city, suburbs, and rural; public and private). The author analyzed these data, and compared the results with ANSI S12.60-2002 performance criteria. It was found that the background noise levels were around 50 dBA. This is 15 dBA above the standard requirement. A majority of the reverberation times were in line with the 0.6-second criteria, but a significant number had reverberation times around 1 second.
Geoacoustic inversion of data collected in two ‘‘typical’’ shallow-water environments
Authors: Nielsen Peter , Siderius Martin
Published: October 2013

Two distinct types of shallow-water experiments were recently conducted by SACLANTCEN in different shallow-water areas (<150 m) to perform geoacoustic inversion of received acoustic signals. A towed sound source–horizontal line array was used in one of the experiments, and in the other the source and vertical array were moored on the bottom. The two experimental configurations were deployed in two areas with soft and hard bottom properties in order to investigate (1) the performance of geoacoustic inversion using horizontal and vertical line arrays, and (2) the robustness of the inversion method to different bottom characteristics. The transmitted signals were 1-s linear frequency modulated sweeps in the band from 200–800 Hz. The source–horizontal array separation was 300 m and the fixed path between the source and the vertical array was 2 km. This short source–receiver separation minimizes the impact of the range-dependent water-column and seabed properties on the acoustic propagation. The applied geoacoustic inversion technique of the data is the traditional model-based matched-field processing utilizing a global search algorithm. Results from successful geoacoustic inversion in the regions with soft-bottom properties are presented for the two experimental configurations. Severe difficulties appeared when inverting data from the hard-bottom regions and possible causes are given.
The oscillations of vapor bubbles
Authors: Prosperetti Andrea , Yin Z. , Yang B.
Published: October 2013

Bob Apfel had so many interests that it is impossible—however fitting and desirable—to pay homage to his work as a whole. Some of his early studies were devoted to bubble nucleation at high superheats. In the first part of this paper a recent application of this phenomenon is described. Once a vapor bubble is generated, its subsequent oscillations (free and forced) present analogies and differences with those of a gas bubble: the second part of the paper focuses on this topic. [Work supported by NSF and NASA.]
Light-scattering measurements of cavitation from ultrasound contrast agent bubbles
Authors: Guan Jingfeng , Chen Wen-Shiang , Matula Thomas
Published: October 2013

Ultrasound contrast agents are typically micron-sized gas bodies with stabilizing shell coatings. The shell prevents the gas bubble from dissolving. The shell also changes a bubble’s scattering properties and affects a bubble’s destruction. Optimization of the shell can be beneficial for diagnostic imaging and therapeutic ultrasound applications. Thus, understanding agent response to pulsed ultrasound is important. However, because the agents are so small, their response to pulsed ultrasound is difficult to measure. Until recently, the only tool available for measuring contrast agent dynamics was a very expensive high-speed camera. We have been investigating the use of light-scattering to measure aspects of cavitation from contrast agents in which a small HeNe laser beam scatters off a bubble and is focused onto a photomultiplier tube detector. Previous experiments have involved clusters of agents, where collective bubble oscillations and destruction were observed. Our current apparatus is designed to observe single-bubble oscillations from a diagnostic ultrasound system. The advantages for using light-scattering include small cost and the ability to monitor bubble oscillations for extended times. The technique will be described, and representative data samples will be shown.
Providing audible information relating to the differences in monophonic and multichannel sound reinforcement systems using computer auralization
Authors: Coffeen Robert C.
Published: October 2013

When selecting the sound distribution system for a particular venue, there is often a decision to be made as to the audible differences between a monophonic and potentially less expensive loudspeaker system and a multi-channel and potentially more expensive system. Computer auralization is a tool that can be used for auditioning the approximate differences between single channel and multi-channel loudspeaker systems.
Virtual AM stereo and surround sound to setup AM/FM radio theatre
Authors: Vadivelmurugan Selvakumaran , Veeraraghavan K. , Govindan Sharavan V.
Published: October 2013

Introduction of virtual surround sound and stereo to AM radio has been proposed in this study. This technology can be further applied to aid the construction of an AM radio theatre. Adding to the advantages of AM, the lower bandwidth, higher range, and simpler circuitry, AM can now offer excellent sound effect with the post-transmission process. The motivation for the introduction of virtual surround sound is the poor quality of AM sound. In this study, the response by human ear has been thoroughly investigated and the methodology to create virtual surround sound has been developed. The elements essential to setup audio theatre such as the components of audio chain, multiple unit audio speaker, inner section of the ear, psychological effect of different ranges of frequencies, and radio theatre design have been extensively studied on the basis of Helmholtz audition theory. The vital changes include the different frequency division multiplexing of message at the transmitting end, three phases of the process, resulting in the vertical and horizontal digital connection, espresso program, and the 3×12 speaker design theatre.
Acoustically driven spherical implosions and the possibility of thermonuclear reactions
Authors: Gaitan D. Felipe , Tessien Ross
Published: October 2013

Acoustically driven, gas-filled cavities in liquids have been known to collapse violently, generating short flashes of light of ∼100-ps duration. More recently, the possibility of generating fusion reactions using acoustics (acoustic inertial confinement fusion) has been considered. Results of computer simulations using the HYADES hydrocode (Cascade Applied Sciences, Inc) plus the SESAME equations of state for free collapsing and acoustically driven cavities in molten metals will be presented as well as experimental data at high ambient pressures in different liquids. Back-of-the-envelope calculations in terms of the acoustical and thermodynamic parameters necessary to achieve thermonuclear reactions will be presented in an effort to evaluate the feasibility of acoustic ICF as an energy source.
Litho-Fusion and HIFUsion: Alternative ways to generate hot bubbles?
Authors: Matula Thomas , Hilmo Paul , Bailey Michael , Crum Lawrence
Published: October 2013

The recent sonofusion experiments at Oak Ridge National Laboratory utilized standing acoustic wave fields that produced negative pressures of about 15 atm. The generated bubbles were thought to grow from around 100 nm to a maximum size of about 1 mm, before collapsing violently. There are other means for generating bubbles that grow to millimeter sizes. For example, in lithotripsy, a focused shock wave (Pa∼−100 atm) creates bubbles that grow to millimeter sizes. High-intensity focused ultrasound (HIFU) pulses can also generate large bubbles. Can these systems be used to investigate extreme bubble collapse violence? We will describe our efforts in generating and observing bubbles from these systems. If time permits, we will also point out that bubbles in a standing wave undergo translational motion, and this motion may lead to instabilities.
Modeling the representation of speech sounds in auditory cortical areas
Authors: Guenther Frank H. , Tourville Jason A. , Bohland Jason W.
Published: October 2013

Many studies have shown that sounds from near the center of a sound category (such as a phoneme from one’s native language) are more difficult to discriminate from each other than sounds from near a category boundary. However, the neural processes underlying this phenomenon are not yet clearly understood. In this talk we describe neural models that have been developed to address experimental data from psychophysical and functional brain imaging experiments investigating sound representations in the cortex. Experiments investigating the effects of categorization and discrimination training with nonspeech sounds indicate that different training tasks have different effects on sound discriminability: discrimination training increases the discriminability of the training sounds, whereas learning a new sound category decreases the discriminability of the training sounds within the category. These results can be accounted for by a neural model in which categorization training causes a decrease in the size of the cortical representation of central sounds in the category, while discrimination training leads to an increase in the cortical representation of training sounds. This model is supported by brain imaging results for speech and nonspeech sounds. Experimental results further suggest preferential utilization of different auditory cortical regions when subjects perform identification versus discrimination tasks.
Multipath compression by multiple convolutions
Authors: Smith George B.
Published: October 2013

Blind deconvolution algorithms can be useful as pre-processors for signal classification algorithms in shallow water. These algorithms remove the distortion of the signal caused by multipath propagation when no knowledge of the environment is available. A very simple blind algorithm is presented here which utilizes convolutions of multiple data channels for convolutional smoothing of multipath. Computer simulation studies show significant performance improvement when propagation effects are mitigated by the use of this blind technique. [Work supported by ONR and the Naval Research Laboratory.]
A new loudspeaker design: A case study of an effort to more fully integrate the loudspeaker into the playback room in a musical way
Authors: Moulton David , Praestgaard Poul
Published: October 2013

The authors have been members of a design and development team that has created a new loudspeaker that attempts to resolve several of the primary problems presented by the loudspeaker/room/listener interface, as described in one of the author’s previous papers. This paper will describe that new loudspeaker, its various new approaches to the interactions between the loudspeaker, the room and the listeners, and a brief review of the research, findings and assumptions underlying its design. The authors hope to have examples of the loudspeaker available for demonstration.
Physical modeling synthesis of recorder sound
Authors: Shiraiwa Hiroko , Kishi Kenshi , Nakamura Isao
Published: October 2013

A time-domain simulation of the soprano baroque recorder based on the digital waveguide model (DWM) and an air reed model is introduced. The air reed model is developed upon the negative acoustic displacement model (NADM), which was proposed for the organ flue-pipe simulation [Adachi, Proc. of ISMA 1997, pp. 251–260], based on the semiempirical model by Fletcher [Fletcher and Rossing, The Physics of Musical Instruments, 2nd ed. (Springer, Berlin, 2000)]. Two models are proposed to couple DWM and NADM. The jet amplification coefficient is remodeled for the application of NADM for the recorder, regarding the recent experimental reports [Yoshikawa and Arimoto, Proc. of ISMA 2001, pp. 309–312]. The simulation results are presented in terms of the mode transient characteristics and the spectral characteristics of the synthesized sounds. They indicate that the NADM is not sufficient to describe the realistic mode transient of the recorder, while the synthesized sounds maintained almost resemble timbre to the recorder sounds.
Sensitivity to array tilt and bow for broadband geoacoustic inversion using a towed array
Authors: Yoo K. , Yang T. C. , Fialkowski L. , Dacol D. , Perkins John , Fallat M. , Nielsen P. , Siderius M.
Published: October 2013

During the MAPEX 2000 experiment, broadband acoustic data from an acoustic source were received on a towed array, both towed by the same ship with the source–receiver range kept nearly constant. The data were used to invert for the geoacoustic properties of the bottom along the ship track. The experiment was conducted by the SACLANTCEN in the Sicily Strait where the bottom layer profile was also surveyed using standard seismic methods. The geoacoustic inversion results from the towed array data showed good agreement with the seismic data [M. Siderius et al., J. Acoust. Soc. Am. 112, 1523 (2002); M. Fallat et al., SACLANTCEN Report No. SM-402, 2002] using a matched field correlation cost function that summed over frequencies coherently (for each phone) and summed over the phones incoherently. The authors reported that an approach that sums the matched-field correlation coherently over phones and incoherently over frequencies did not yield as good a result as the method mentioned above. The array tilt and bow may be one factor that impacts correlation functions in different ways. We study in this paper the matched field inversion sensitivity to the array tilt and bow as applied to the MAPEX 2000 data. [Work supported by ONR.]
Unified inversion using isolated moving sources
Authors: Stotts Steven A. , Koch Robert A. , Neilsen Traci B. , MacInnes Craig S.
Published: October 2013

Geoacoustic inversion using beamformed data from a ship of opportunity has been demonstrated with a bottom mounted array [Koch and Knobles, J. Acoust. Soc. Am. 112, 2282 (2002)]. An alternative approach transforms element level data into ‘‘beam space,’’ applies a bearing filter [MacInnes, IEEE J. Ocean. Eng. (submitted)] and transforms back to element level data prior to performing inversions [T. B. Neilsen and C. S. MacInnes (unpublished]. Automation of this filtering approach is facilitated for broadband applications by restricting the inverse transform back to element data corresponding to the degrees of freedom of the array, i.e., the effective number of elements. Examples that demonstrate this filtering technique with simulated data are presented along with comparisons to inversion results using beamformed data. Vertical and horizontal ambiguity surfaces are compared for the two approaches. Examinations of cost functions calculated within a simulated annealing algorithm reveal the efficacy of the approach. Filter performance with real data will be discussed.
Hearing and hearing loss: Causes, effects, and treatments
Authors: Schmiedt Richard A.
Published: October 2013

Hearing loss can have multiple causes. The outer and middle ears are conductive pathways for acoustic energy to the inner ear (cochlea) and help shape our spectral sensitivity. Conductive hearing loss is mechanical in nature such that the energy transfer to the cochlea is impeded, often from eardrum perforations or middle ear fluid buildup. Beyond the middle ear, the cochlea comprises three interdependent systems necessary for normal hearing. The first is that of basilar-membrane micromechanics including the outer hair cells. This system forms the basis of the cochlear amplifier and is the most vulnerable to noise and drug exposure. The second system comprises the ion pumps in the lateral wall tissues of the cochlea. These highly metabolic cells provide energy to the cochlear amplifier in the form of electrochemical potentials. This second system is particularly vulnerable to the effects of aging. The third system comprises the inner hair cells and their associated sensory nerve fibers. This system is the transduction stage, changing mechanical vibrations to nerve impulses. New treatments for hearing loss are on the horizon; however, at present the best strategy is avoidance of cochlear trauma and the proper use of hearing aids. [Work supported by NIA and MUSC.]
Boundary damping of flexural vibrations in beams and plates
Authors: Garrelick Joel
Published: October 2013

The damping of resonantly enhanced flexurally vibrating beams and plates is typically accomplished with surface treatments, viz. constrained or unconstrained damping layers. Alternatively, damping may be achieved at boundaries. In some sense this is a more fundamental approach in that for homogeneous plates, it is the boundaries that are solely responsible for resonant behavior. The theoretical performance of boundary treatments is unbounded, provided the treatment is full, that is continuous along the extent of the boundary. This is not the case however with partial coverage, where a portion of the boundary is left bare. The bounds for such treatments are explored in this paper. The treatment itself is defined in terms of a single bounce reflection coefficient (RC). It is found that for boundary damping in one dimension, viz., beams, the effective loss factor for individual modes is frequently invariant with either one or both ends treated, assuming RC constant. This is in contrast to the two-dimensional case, viz., thin plates, where analogous loss factor values are frequency dependent. Illustrative examples are presented and analyzed. [Work partially performed at CAA/Anteon Corp. and supported by NSWCCD and NSSC, Code 93R.]
What is the best method for structural damping identification? Part 2: Comparison of performance
Authors: Phani Srikantha , Woodhouse J.
Published: October 2013

Damping identification in structural vibration from measured frequency response functions is a difficult task. Several methods have been proposed in the literature to identify the damping matrix. Some employ modal parameters such as natural frequencies, damping factors, and mode shapes, while others work directly from the frequency response function matrix. In practice, in the presence of noise and incompleteness of data, it is hard to guess how well any of these methods will perform. This paper reports a systematic simulation study to test the relative benefits/disadvantages of a wide range of approaches, existing and novel. Representative model systems have been chosen to test performance under various conditions of measurement noise, system complexity, damping type, modal overlap factor, and modal truncation. A very wide range of results is summarized by computing various norms of performance for all the methods studied. Recommendations are made for the best methods to extract reliable damping information from practical measurements.
Monaural speech segregation
Authors: Wang DeLiang , Hu Guoning
Published: October 2013

Speech segregation from a monaural recording is a primary task of auditory scene analysis, and has proven to be very challenging. We present a multistage model for the task. The model starts with simulated auditory periphery. A subsequent stage computes midlevel auditory representations, including correlograms and cross-channel correlations. The core of the system performs segmentation and grouping in a two-dimensional time-frequency representation that encodes proximity in frequency and time, periodicity, and amplitude modulation (AM). Motivated by psychoacoustic observations, our system employs different mechanisms for handling resolved and unresolved harmonics. For resolved harmonics, our system generates segments—basic components of an auditory scene—based on temporal continuity and cross-channel correlation, and groups them according to periodicity. For unresolved harmonics, the system generates segments based on AM in addition to temporal continuity and groups them according to AM repetition rates. We derive AM repetition rates using sinusoidal modeling and gradient descent. Underlying the segregation process is a pitch contour that is first estimated from speech segregated according to global pitch and then adjusted according to psychoacoustic constraints. The model has been systematically evaluated, and it yields substantially better performance than previous systems.
How does spatial hearing affect cocktail party conversations?
Authors: Shinn-Cunningham Barbara G.
Published: October 2013

Although spatial cues are not a dominant factor in auditory scene analysis by humans, spatial separation of a target talker and an interfering sound source often increases the intelligibility of the target. A large portion of this improvement arises from a simple acoustic effect: separating the target and interferer generally increases the target-to-interferer energy ratio at one ear. When the target is near threshold, binaural processing provides an additional small, but important improvement. Finally, in conditions where both target and interferer are audible but are difficult to segregate, spatial separation can improve the ability to stream the sources and interpret the target message. The echoes and reverberation present in everyday environments influence all of these factors, altering the target-to-interferer energy ratio, the effectiveness of binaural processing, and the ability to stream the sources. A number of studies will be reviewed to demonstrate how these different factors influence speech intelligibility and affect cocktail party conversations in everyday environments. [Work supported by the Air Force Office of Scientific Research and the Alfred P. Sloan Foundation.]
Application of Hilbert space decomposition to acoustical inverse problems
Authors: Lehman Sean K.
Published: October 2013

In a recently developed theory, the forward integral acoustic scattering operator is cast into the formalism of a Hilbert space operator which projects the continuous space scattering object into the discrete measurement space. By determining the singular value decomposition (SVD) of the forward scattering operator, one obtains optimal, orthonormal bases for each of these spaces in the form of the singular vectors. In formulating the inverse scattering problem, it is best to express the unknown object distribution in terms of an expansion of the singular vectors. Using this expansion, the best reconstruction, in a LMS sense, can be obtained from measured scattered field data. We present reconstruction results using this new theory. [Work performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.]
Richard H. Bolt’s work on theoretical aspects of room acoustics
Authors: Lyon Richard H.
Published: October 2013

From about 1940 to 1950 Dick Bolt undertook a number of studies of the transmission of sound in a room. These were mostly theoretical and appear to have had two sources of inspiration: the work of Wente at Bell Laboratories in the 1930s, and Philip Morse’s work on the eigenfunctions and eigenvalues of idealized rooms in the early 1940s. In 1944, the Reviews of Modern Physics published in its April issue a single paper—that of Dick Bolt and Phil Morse, titled ‘‘Sound waves in rooms.’’ This tour de force took the viewpoint that a deterministic calculation of the modes of an idealized room could reveal important features of the acoustics of less ideal spaces. The relations between wall impedance and modal damping for axial, tangential, and oblique modes and the construction of direct fields from modal expansions are worthy of special note. Perturbation analysis is used to couple idealized modes as a first attempt to deal with ‘‘real’’ rooms and the transition to ergodic behavior. This work then led Bolt to a number of studies of the irregularity of spacing of modal resonance frequencies, which had some influence, in turn, on models of modal distributions in Statistical Energy Analysis.
Richard H. Bolt—Mentor and colleague
Authors: Wetherill Ewart A.
Published: October 2013

Of his many accomplishments in acoustics, perhaps one of Richard H. Bolt’s greatest legacies will prove to be his contribution, both directly and through his teaching, to everyday hearing conditions in buildings. In a discipline that attempts to bridge the technical and cultural gap between a pure science and the pragmatic and often-haphazard process of building design, he combined a deep understanding of both professions with an ability to communicate complex ideas that is reminiscent of Wallace Clement Sabine. His welcoming enthusiasm and humility enabled him to attract and to work well with people of complementary talents, in both theoretical research and the gritty details of a consulting practice, as well as to envision the potential of still-unexplored subjects. A logical outcome of this combination was the profoundly influential technical group known as BBN, whose pioneering integration of acoustics with building technology is echoed by many consulting groups throughout the world.