bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of precedence effect behavior in anechoic chamber with that in ordinary room
Authors: Abe Koji , Takane Shouichi , Sato Sojun , Watanabe Kanji
Published: May 2013

The precedence effect is well known as one of auditory illusions occurred by using multiple sound sources with similar sound output. When a sound is followed by similar sound separated with relatively short time delay, a single fused sound image is localized at the source position corresponding to the first-arriving sound. This feature is applicable to public address systems, which make audience perceive the sound image different from the actual sound source positions prepared for the system, with some sound reinforcement achieved. In spite of many studies in this phenomenon, the behavior of the precedence effect has been investigated for limited sound source arrangements in laboratory environments like anechoic chamber. On the other hand, this behavior in the ordinary room is not obvious, and it is effective to clarify the difference of the behavior of the precedence effect in anechoic chamber from that in the ordinary room for the application of the precedence effect to the public address system. In this study, the similar sound sources were installed both in the lecture room and in the anechoic chamber, and the behavior of the precedence effect was compared each other with the given time and level difference among sound sources.
Teaching acoustics at architect students using digital tools
Authors: Bard Delphine , Kristiansen Tina-Henriette , Frühwald Hansson Eva
Published: May 2013

At the School of Architecture, Lund University Sweden, courses are taught in different ways. A large part of the education during year one and two is held as “studios,” doing creative (individual) project work. Usually acoustics courses rather correspond to the traditional engineering education style, using lectures, exercises, small project works, and final written examination. The problem is that many students do not know how to use the gathered information in their creative works. The aim of the study covered by this paper was to improve upon the existing teaching/learning of the fundamental acoustics principles scheme by introducing new methodologies. In order to achieve our goal, we gave the students two different assignments: In the first assignment, the students had to produce short educational movies to explain and teach acoustics principles to their peers. In the second assignment, they should implement the new knowledge gathered in the first assignment into their individual creative projects.
Preferences for melodic contours transcend pitch
Authors: Graves Jackson , Micheyl Christophe , Oxenham Andrew J.
Published: May 2013

The question of what makes a good melody has interested composers, music theorists, and psychologists alike. Many of the observed principles of good “melodic continuation” involve the melodic contour—the pattern of rising and falling pitch within a sequence. Recent work has shown that contour perception can extend beyond pitch to other auditory dimensions, such as timbre and loudness. Here we show that the generalization of contour perception to non-traditional dimensions also extends to melodic preferences and expectations. We find that subjective continuation ratings for sequences that vary in brightness or loudness generally conform to the same contour-based expectations as pitch sequences. The results support the hypothesis that contour perception is a general auditory phenomenon, and suggest that the well-known preference for narrow ranges and small intervals in melodies is not unique to the dimension of pitch. [Work supported by NIH Grant R01DC05126 and by the Undergraduate Research Opportunities Program of the University of Minnesota.]
Loudspeakers and headphones: The effects of playback systems on listening test subjects
Authors: King Richard L. , Leonard Brett , Sikora Grzegorz
Published: May 2013

Many modern listening test designers disagree on the best playback system to be used when conducting tests. The preference often tends toward headphone-based monitoring in order to minimize the possibility of undesirable acoustical interactions with less than ideal testing environments. On the other hand, most recording and mixing engineers prefer to monitor on loudspeakers, citing a greater ability to make critical decisions on level balances and effects. While anecdotal evidence suggests that differences exist between systems, there is little quantified, perceptually based data to guide both listening test designers and engineers in what differences to expect when alternating between monitoring systems. Controlled tests are conducted with highly trained subjects manipulating the level of solo musical elements against a backing track, using both headphones and loudspeakers. This task serves to make the results equally applicable to critical mixing tasks and rigorous listening tests. The results from both playback systems are compared, showing a defined difference in the mean levels set on the two different monitoring systems. Likewise, the variance seen across subjects is larger when monitoring on headphones than on loudspeakers, lending credence to the hypothesis that tests conducted on one playback system may not be equally applicable to the other.
A comparison of survey implementation methods
Authors: Krecker Peg , Koenig Carrie , Wilmer Clifton , Page Juliet A.
Published: May 2013

As part of a pilot program to measure subjective response to low level sonic booms, 52 residents at Edwards Air Force Base were recruited to answer questions about their reactions to low-amplitude sonic booms. Over a two-week period, participants completed brief surveys (12 items) each time they heard a sonic boom and a short summary form at the end of each day. The study used three modes of survey administration—paper, Web, and Apple mobile device—to support analysis of the effectiveness of different approaches. Previous research on subjective response to sonic booms or other impulsive noise with similar measurement objectives has used in-person surveys, telephone surveys, or computer-assisted self-administered methods similar to a Web survey, but study designs prevented direct comparisons of the methods on the same sample of participants. We examine data quality across the three modes and the paper will present results on completion rates by survey mode, variation in completion rates over time, and differences in the timeliness of response for web and Apple participants. Qualitative interviews with a subset of participants yield further insights into each approach.
Investigating soundscape affordances through activity appropriateness
Authors: Nielbo Frederik L. , Steele Daniel , Guastavino Catherine
Published: May 2013

Central to the concept of soundscape is the understanding of the acoustic environment in context. Previous research indicates that people understand soundscapes through their potential for activities. One way to look at activities is through the concept of affordances—defined as the actionable properties of an object. In this study, the object is a location and time in the city. Fifteen participants listened to stereo recordings of eight outdoor sites in Paris and Montreal. In each trial, they evaluated on a continuous scale how appropriate the soundscapes were for a given activity. Four activities were considered and presented in random order: studying for an exam, meeting up with a friend, riding a bike and relaxing. Participants justified their ratings in free-format comments. A 8(Soundscapes) x 4(Activities) factorial ANOVAs revealed significant effects of Soundscape and Activities and Soundscape*Activities on appropriateness ratings. Certain soundscapes were found to accommodate specific activities only while others were found to potentially accommodate all activities or none (prominent mechanical/traffic noise). We also analyzed comments to further understand how participants envision utilizing the soundscape/environment and attribute meanings to the various sounds present.
Experimental measurements of the coherent field resulting from the interaction of an ultrasonic shock wave with a multiple scattering medium
Authors: Viard Nicolas , Gianmarinaro Bruno , Derode Arnaud , Barrière Christophe
Published: May 2013

Whereas multiple scattering and shock wave formation are known to be antagonistic phenomena, this work concentrates on the interaction of an ultrasonic shock wave with a random multiple scattering medium. The shock wave is generated by long distance propagation of a short pulse (four periods at a 3.5 MHz central frequency) in water before it encounters the scattering medium (a slab-shaped random set of parallel metallic rods). Transmitted waves are recorded over hundreds of positions along the lateral dimension of the slab to estimate the ensemble-averaged transmitted field 〈Φ(t)〉, also known as the coherent wave. Experiments are repeated for different thicknesses L of the slab and different emission amplitudes. The elastic mean free path le (i.e., the typical distance for the decreasing of the coherent intensity ∣〈Φ(t)〉∣2 due to scattering) is determined as well as the harmonic rate of the averaged transmitted wave. Experimental results are discussed and compared to the linear case.
Understanding subtle changes in auditory function with otoacoustic emissions
Authors: Hood Linda J. , Brashears Shanda , Long Glenis , Talmadge Carrick
Published: May 2013

Otoacoustic emissions (OAEs), a sensitive measure of cochlear processing, may be altered by subtle changes in auditory function that are not measurable by usual clinical methods. We studied auditory function in carriers of genetic mutations related to recessive hereditary hearing loss where we hypothesized that carrying a single mutation copy may compromise auditory function and be reflected when sensitive assays are used. Parents and siblings who were confirmed carriers of recessive mutations associated with GJB2 (connexin 26) or Usher syndrome, as well as obligate carriers of mutations related to recessive hearing loss of unknown genetic origin, were compared to age and gender matched control subjects. All participants had normal pure tone and middle ear responses. Metrics included transient OAEs, distortion product OAEs, and OAE fine structure. DPOAE fine structure was specifically explored based on the ability to isolate components that could be differentially affected by genetic mutations. The results support the hypothesis that carriers of gene mutations related to hearing loss display subtle auditory abnormalities that can be observed in OAEs. These findings will be related to other studies of subtle changes in OAEs in disorders affecting auditory function. [Work supported by NIH NIDCD R01-DC03679 and VU Development Funds.]
The influence of auditory training on measures of temporal resolution in younger and older adults
Authors: Avivi-Reich Meital , Arnott Stephen R. , Tavares Tamara , Schneider Bruce A.
Published: May 2013

Deterioration in the ability to perceived rapid changes in auditory input is thought to contribute to the difficulties older adults experience when communicating in noise. Studies have demonstrated that the performance of young adults on auditory tasks improves with training. However, few studies have tested the degree to which practice improves auditory performance in older adults. A previous study examined the extent to which younger and older adults benefited from training when the task was to detect a gap in a narrow-band noise centered at 1 kHz. Significant improvements occurred in both age groups, indicating that auditory learning can still occur later in life. The present study examines if training improves performance when more than one auditory filter is activated. Twenty-four younger and older participants were trained for 10 days to detect a gap between a 2-kHz and a 1-kHz noise. Performance was assessed one day and one month after the last training session along with the extent to which the benefits generalized to other frequencies and the untrained ear. In addition, event-related potentials (ERPs) were obtained pre- and post-training to assess cortical changes in the response to temporal gaps. Initial results show improvement throughout training in both age groups.
Psychometric effects of adding realism to a speech-in-noise test
Authors: Best Virginia , Keidser Gitte , Buchholz Jörg M. , Freeston Katrina
Published: May 2013

The speech reception threshold (SRT) is routinely measured in the laboratory to assess speech understanding in noise, but is often reported to be a poor predictor of performance in real world listening situations. The overall goal of this work is to determine whether introducing realistic aspects to speech tests can better capture individual differences and ultimately produce more relevant performance measures. We examined the psychometric effects of (a) transplanting a standard sentence-in-noise test into a simulated reverberant cafeteria environment, and (b) moving from sentence recall to a new ongoing speech comprehension task. Participants included normal hearers and hearing-impaired listeners (who were tested with and without their hearing aids). SRTs in the cafeteria environment were significantly correlated with standard SRTs, but were poorer overall and more sensitive to hearing loss. The comprehension task, despite having very different demands to sentence recall, produced similar SRTs under these conditions. The benefit of hearing aids was weakly correlated across the two listening environments and the two listening tasks. These manipulations promise to be useful for the creation of realistic laboratory tests that are engaging and challenging, yet controlled enough to be useful for psychophysical experiments.
Magnitude of speech-reception-threshold manipulators for a spatial speech-in-speech test that takes signal-to-noise ratio confounds and ecological validity into account
Authors: Ro/nne Filip M. , Laugesen So/ren , Jensen Niels S. , Hietkamp Renskje K. , Pedersen Julie H.
Published: May 2013

Measuring speech-reception threshold (SRT) using adaptive procedures is popular, as testing yield results with desirable statistical properties. However, SRT measures have drawbacks related to the unbounded nature of the signal-to-noise ratio (SNR) at which the SRT is achieved. Often the SRT will be a double-digit negative number, which compromises the ecological validity of the result. If testing involves hearing aids, it means that these devices and the signal-processing algorithms in them may be operating in conditions for which they were not intended. Further, the commonly observed large spread in SRT (both between- and within-group) has the possibility to cause SNR confounds that may lead to faulty conclusions. One way to address these issues is to provide the experimenter with SRT manipulators, to control the SNR at which testing takes place for the individual listener. The present work aims at developing a spatial speech-in-speech test with a selection of SRT manipulators for the experimenter to choose from. The manipulators investigated in this study are as follows: the spatial separation between target and maskers, the number of spatially separated maskers, changing the masker gender, and scoring in words versus sentences. The magnitudes of the SRT manipulators were investigated using 20 hearing-aid users as listeners.
Attentional switching when listeners respond to semantic meaning expressed by multiple talkers
Authors: Hafter Ervin R. , Xia Jing , Kalluri Sridhar , Poggesi Rosa , Hansen Claes , Whiteford Kelly
Published: May 2013

The “cocktail party problem” asks how we know what one person says when others are speaking at the same time. With interest in the difficulty faced by older and hearing-impaired listeners in multi-talker environments, the present experiment looks at the speed of shifting attention between talkers. In our simulated cocktail party, a subject sits among multiple talkers who are each telling a different story. A sequence of questions are drawn from the various stories and presented visually for subjects to answer with manual responses. Pay is based on correct answers, and attention is assessed by comparing response accuracy on questions from the talker identified visually as the primary and from the other talkers. Attention is manipulated by varying the primary talker at random, from question to question. The speed of shifting attention is measured by varying the time from when the new primary is identified to the moment when the relevant information appears in that story. In a related study, bilingual subjects must shift attention to talkers speaking either English or Spanish. This allows determination of the additional time needed to switch languages within a multi-talker environment.
Relationship between distortion and working memory for digital noise-reduction processing in hearing aids
Authors: Arehart Kathryn , Souza Pamela , Lunner Thomas , Syskind Pedersen Michael , Kates James M.
Published: May 2013

Several recent studies have shown a relationship between working memory and the ability of older adults to benefit from specific advanced signal processing algorithms in hearing aids. In this study, we quantify tradeoffs between benefit due to noise reduction and the perceptual costs associated with distortion caused by the noise reduction algorithm. We also investigate the relationship between these tradeoffs and working memory abilities. Speech intelligibility, speech quality, and perceived listening effort were measured in a cohort of elderly adults with hearing loss. Test materials were low-context sentences presented in fluctuating noise conditions at several signal-to-noise ratios. Speech stimuli were processed with a binary mask noise-reduction strategy. The amount of distortion produced by the noise reduction algorithm was parametrically varied by manipulating two binary mask parameters, error rate, and attenuation rate. Working memory was assessed with a reading span test. Results will be discussed in terms of the extent to which intelligibility, quality, and effort ratings are explained by the amount of distortion and/or noise and by working memory ability. [Funded by NIH, Oticon, and GN ReSound.]
Development of a novel hearing-aid for the profoundly deaf using bone-conducted ultrasonic perception: Assessments of the modulation type with regard to articulation, intelligibility, and sound quality
Authors: Nakagawa Seiji , Fujiyuki Chika , Okubo Yuko , Kagomiya Takayuki , Hotehama Takuya
Published: May 2013

Bone-conducted ultrasound (BCU) is perceived even by the profoundly sensorineural deaf. We have developed a novel hearing-aid using BCU perception (BCU hearing aid: BCUHA) for the profoundly deaf. In the BCUHA, ultrasonic sinusoids of about 30 kHz are amplitude-modulated by speech and presented to the mastoid. Generally, two sounds are perceived: one is a high-pitched tone due to the ultrasonic carrier, with a pitch corresponding to a 8–16 kHz air-conducted (AC) sinusoid, and the other is the envelope of the modulated signal. As a method of amplitude modulation (AM), double-sideband with transmitted carrier (DSB-TC) modulation had been used; however, the DSB-TC is accompanied by a strong high-pitched tone. In this study, two new AM methods, double-sideband with suppressed carrier (DSB-SC) and transposed modulation (TM), that can be expected to reduce the high-pitched tone were newly employed in the BCUHA, and their resulting articulations, intelligibilities, and sound qualities were evaluated. The results showed that DSB-TC and TM had higher articulation and intelligibility scores than DSB-SC. Further, in terms of sound quality, the TM speech was closer than other types of BCU speech to AC speech. These results provide useful information for further development of the BCUHA.
Effects of phonetic experience on neural processing of English /r/ and /l/ by Korean and Japanese listeners
Authors: An Lee Jung , Martin Brett A. , Long Glenis R.
Published: May 2013

The effects of phonetic experience on behavioral and neurophysiological processing of English /r/ and /l/ by Koreans and Japanese were compared to speakers of American English. Although English /r/ and /l/ are not phonemic in both Korean and Japanese languages, Koreans have a pseudo phonetic [ɾ]-[ll] model available for perception of English, /r/-/l/ sounds in medial position, while Japanese do not. Speech stimuli were a continuum of synthetic stimuli ranging from perceived /iri/ to perceived /ili/. To date, five subjects in each language group have been tested. As predicted, behavioral results show that English medial /r/ and /l/ were perceived in a categorical manner by Americans, in a categorical-like manner by Koreans and in a non-categorical manner by Japanese. Neural responses tapped by the ACC did not differ significantly between language groups for P1-N1-P2, suggesting little effect of phonetic experience on the encoding of these sounds. In contrast, the T-complex (Tb latency and Ta morphology) differed significantly between groups. The T-complex morphology had double-peaks in the Japanese group. These findings suggest that the T-complex may index the effects of phonetic experience on speech perception.
Continuous recognition memory for spoken words in noise
Authors: Brouwer Susanne
Published: May 2013

Previous research has shown that talker variability affects recognition memory for spoken words [Palmeri et al., (1993)]. This study examines whether additive noise is similarly retained in memory for spoken words. In a continuous recognition memory task, participants listened to a list of spoken words mixed with noise consisting of a pure tone or of high-pass filtered white noise. The noise and speech were in non-overlapping frequency bands. In experiment 1, listeners indicated whether each spoken word in the list was “old” (heard before in the list) or “new.” Results showed that listeners were as accurate and as fast at recognizing a word as old if it was repeated with the same or different noise. In experiment 2, listeners also indicated whether words judged as “old” were repeated with the same or with a different type of noise. Results showed that listeners benefitted from hearing words presented with the same versus different noise. These data suggest that spoken words and temporally overlapping but spectrally non-overlapping noise are retained or reconstructed together for explicit, but not for implicit recognition memory. This indicates that the extent to which noise variability is retained seems to depend on the depth of processing.
Can physical metrics identify noise reduction settings that optimize intelligibility?
Authors: Hilkhuysen Gaston , Huckvale Mark
Published: May 2013

Noise reduction algorithms often include adjustable parameters. Their settings can have important consequences for the intelligibility of an enhanced noisy speech signal, but it is not clear how to choose the best settings. In previous work, we have found that even experienced listeners prefer non-optimal settings, which degrade intelligibility. Measuring the effect of settings directly using an intelligibility listening task is often infeasible because of time, cost, or the large number of parameter combinations. In this paper we investigate whether physical intelligibility metrics can provide an efficient mean to optimize settings for noise reduction. A number of intelligibility metrics can be found in the recent research literature. An evaluation of these metrics has shown disappointing performance in their abilities to predict the absolute intelligibility of enhanced noisy speech. However, to find optimal settings, it may be sufficient to predict the relative change in intelligibility caused by a parameter change. Five metrics were used to predict the optimal settings of two parameters of a noise reduction system. The change in each metric with parameter settings are compared to listeners’ performance on an intelligibility test with the enhanced signals. We show which metrics are best suited.
A polar-coordinate-discretized wave equation finite-difference time-domain simulation for controlling the emission characteristics of sound source
Authors: Nakano Kota , Nakayama Masato , Nishiura Takanobu , Yamashita Yoichi , Kimura Toshiyuki
Published: May 2013

In sound field simulation with conventional WE-FDTD, the simulated field and wave equation are discretized with symbol time domain and spatial domain with Cartesian coordinate, and sound pressure distribution is calculated. Spatial-discretization with Cartesian coordinate easily achieves calculation and sound synthesis. However, the discretized Cartesian coordinate cannot model sound emission characteristic exactly, because the emission characteristics is under spherical diffusion and discretize Cartesian coordinate cannot define spherical. Emission characteristic of sound source is indispensable for sound field reproduction. Then, we propose a new approach for WE-FDTD method to simulate emission characteristic of sound source object. Polar coordinate discretization is employed in the new approach instead of Cartesian coordinate. The wave equation with spatial Cartesian coordinate is projected onto polar coordinates, and discretized. The discretized polar coordinate is better way to define spherical wave surface than Cartesian one, and it is expected that the emission characteristics are simulated more exactly. The objective evaluations were conducted for the proposed approach. According to the result, the sound field simulation with the new approach can flexibly define exact emission characteristics. However, the discretized interval of polar coordinate is coarse in distance. Verifying the interval limit is important issue in future work.
Flow noise measurements at strong tidal current area in Uldolmok Waterway
Authors: Ko Myungkwon , Choi Jee Woong
Published: May 2013

Flow noise is a kind of hydrodynamic noise, which is created by turbulent flow in the boundary layer around the hydrophone. Although the turbulent pressure is not a true acoustic noise in that its influence decreases rapidly with distance, it acts as a self-noise source. In general, since the spectrum level of flow noise has been reported to increase rapidly with the increment of flow speed, it is possible to monitor the current velocity from the flow noise measurements. Uldolmok waterway in Korea is one of the locations where currents are very strong, with maximum speed of about 5 m/s. The measurements of flow noise were conducted in Uldolmok waterway using two different shapes of hydrophone. In this talk, the flow noise spectra for various flow speeds will be presented for the frequency range of 20–100 Hz, and the comparison of spectra between two different-shape hydrophones will be given.
Model for underwater noise radiated by submerged wind turbine towers
Authors: Hay Todd , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: May 2013

Sustained tonal noise radiated by towers supporting offshore wind turbines contains energy in frequency bands that may disturb marine mammals, or interfere with passive sonar and seismic sensors and underwater communication equipment. Understanding the generation and propagation of underwater noise due to the operation of wind farms is important for determining strategies for mitigating the environmental impact of these noise sources. An analytic model based on a Green's function approach was previously developed for the sound radiated in the water column by a pulsating cylindrical structure embedded in horizontally stratified layers of viscoelastic sediment [Hay et al., J. Acoust. Soc. Am. 130, 2558 (2011)]. This model has since been adapted to include relaxation and viscous losses in seawater and empirical loss factors for the sedimentary layers. In order to validate the model simulations were compared with reported measurements collected near an operating wind turbine that include radial acceleration of the tower, taken to be the source condition, and sound pressure levels in the water column. For long-range propagation over range-dependent environments, the analytic model has been coupled to a parabolic equation code. Simulations are presented for several bathymetries, sediment types, and tower array configurations. [Work supported by Department of Energy DE-EE0005380.]
Implementing physical constraints for noise only normal mode shape estimation
Authors: Rooney Ian M. , Buck John R. , Wage Kathleen E.
Published: May 2013

Many underwater acoustic tasks employ a vertical line array to sample a continuous wave pressure field. In the absence of strong local sources, the noise sampled by an array consists of both a spatially correlated and a spatially uncorrelated component. The correlated component is generally due to distant sources and can be described in terms of the modes of the waveguide. If the number of propagating modes is less than the array size, the diffuse noise lies within a lower dimensional subspace than the array data. The mode shapes defining this subspace can be estimated from noise measurements. Propagation physics constrain the mode shapes defining this subspace to be real, but the basis vectors obtained from a singular value decomposition of noise snapshots are generally complex. A phase rotation for each basis vector is required to rectify this. This work proposes a weighted average of the phase angles for each element that minimizes the variance of the rotation angle estimate. Simulations compare the proposed algorithm against prior approaches such as rotating each basis vector by the phase of the largest magnitude sample, rotating by the average of the phase, or taking the magnitude and ignoring the phase. [Work supported by ONR.]
Propagation of seismic exploration noise in the Marginal Ice Zone
Authors: Tollefsen Dag , Sagen Hanne
Published: May 2013

This paper presents data from ambient noise recordings in the Marginal Ice Zone (MIZ) in the Fram Strait (deep water) and Barents Sea (shallow water) with focus on noise due to seismic exploration activity. Data were recorded on fields of sonobuoys deployed from P-3C aircraft in June 2011 and May 2012, each covering a 100 km x 100 km area. Recordings from three bouys in each area, from open water to within the solid ice cover, are analyzed for low-frequency (10 Hz–1 kHz) noise levels, with broadband noise due to distant seismic exploration identified. Strong attenuation of this noise component with distance into the MIZ is observed in the shallow-water data, whereas noise levels decrease less with distance in the deep-water data despite under-ice conditions. Propagation loss is modeled using a raytrace model including under-ice reflection loss due to an elastic ice cover, with environment input from the TOPAZ coupled ocean-sea ice model and from satellite images. Properties of the noise field, modeling results, and model-data discrepancies will be discussed. [Data collected under the ACOBAR and WIFAR projects at NERSC.]
Modelled and measured sound levels from a seismic survey in the Canadian Beaufort Sea
Authors: Matthews Marie-Noël R. , MacGillivray Alexander O.
Published: May 2013

JASCO Applied Sciences performed acoustic modeling and measurements to calculate marine mammal exclusion zones for Chevron Canada Limited’s 2012 Sirluaq 3-D seismic program in the Canadian Beaufort Sea. The Sirluaq survey was located in deep water (>650 m), on and beyond the continental slope, and presented unique challenges from both modeling and measurement standpoints. The modeling was performed with JASCO’s Marine Operations Noise Model (MONM), which uses a parabolic-equation-based algorithm to accurately predict N×2-D sound propagation in ocean environments. Sound levels were measured with five calibrated Autonomous Multichannel Acoustic Recorder (AMAR) systems at distances of 50–50 000 m from the airgun array, in water depths ranging from 50 to 1500 m. The sensors were laid out to capture sound levels in both the broadside (perpendicular to survey line) and endfire (along the survey line) directions. The high-resolution digital recordings of seismic sounds were analyzed to determine peak and rms sound pressure levels (SPL), and sound exposure levels (SEL) as functions of range from the airgun array. The model estimates were generally conservative; however, the model predictions at the specific depth of the receivers accurately predicted the existence of a shadow zone and the overall transmission loss trend.
A parabolic equation for under ice propagation
Authors: Metzler Adam M. , Collis Jon M. , Siegmann William L.
Published: May 2013

Parabolic equation methods are useful to accurately and efficiently model propagation in the ocean for range-dependent environments. Most methods treat environments where the ocean surface is a flat perfect reflector. For some problems, the ocean surface characterized as a random rough scattering water-air boundary produces significant effects on the overall propagation. A rough surface parabolic equation has been developed [A. P. Rosenberg, J. Acoust. Soc. Am. 105, 144 (1999)] that extends the split-step Padé approach in the RAM implementation, and others have extended split-step Fourier methods. For an upper ice surface, elasticity should be incorporated into the rough scattering boundary. In this paper, a parabolic equation is presented that captures effects of seismo-acoustic interactions and scattering from a rough surface modeled as rigid as opposed to pressure release. Particular attention is given to upward-refracting sound speed profiles, typically found in Arctic environments, which encourage interactions with an ice surface. The scattering technique can be extended to environments with fluid/ice interfaces. [Work supported by ARL:IR&D.]
Sound Cask: Music and voice communications system with three-dimensional sound reproduction based on boundary surface control principle
Authors: Ikeda Yusuke , Ise Shiro
Published: May 2013

To reproduce a highly realistic sound field reproduction, we have developed a 3-D sound reproduction system based on the boundary surface control (BoSC) principle. We set up an Internet connection among the systems, which enables distant speakers to carry out voice telecommunication by simultaneously hearing the same sound field and sensing the other speakers' simulated positions as if they were in the same location. In this system, a listener can freely move his head, because this system reproduce the sound not only at points near his ears but also an area around his head. In this paper, we introduce the “Sound Cask,” which is a 96-channel sound reproduction system based on the BoSC principle. The Sound Cask is used to realize musical telecommunication as if the performers were all playing in the same hall. The system provides a space large enough to play a small musical instrument such as a violin, which allows listening and communication accompanied with the natural body movements of the performer. Another specific feature of the system is that loudspeakers are installed in every possible direction except the floor. The system is designed to be portable so that it can be assembled or disassembled when needed.
Subjective evaluation of a virtual acoustic system: Trials with three-dimensional sound field reproduced by the “Sound Cask”
Authors: Kobayashi Maori , Ueno Kanako , Yamashita Mai , Ise Shiro , Enomoto Seigo
Published: May 2013

It has been necessary to establish subjective measures for the performance of the virtual acoustic systems. In this paper, we report our trials to evaluate the performance of a three-dimensional sound field reproduction system based on the boundary surface control principle, the “Sound Cask.” First, we introduce our investigations for the experts of audio engineering in order to clarify the difference of auditory impression between the Sound Cask and conventional audio systems. Second, we report psychological and physiological experiments focusing on the advantageous points of the Sound Cask, localization performance, and a clear sense of reality, which were pointed out in the investigations for the experts. Finally, we discuss the issues to be considered for subjective evaluation of virtual acoustic systems for future studies.
Electronic architecture—Recent developments in the design, implementation, and performance of time variant acoustic enhancement systems
Authors: Barbar Steve
Published: May 2013

When an electro-acoustic enhancement system is integrated with architectural surfaces in an enclosed volume, the acoustical conditions experienced throughout the venue result from the interaction between the two. Over two decades, we have encountered performance venues with a variety of sizes, shapes, and configurations. Each venue presents unique challenges in configuring architectural elements, as well as the makeup of the electro-acoustic enhancement system, in order to meet the expectations of the users and the audience. This paper describes important elements germane to a successful outcome—from the essential qualities of system components, to the physics and physiology that enable humans to perceive sonic quality. Examples of performance spaces with unique physics and system integration will be discussed.
A six sensor method for measuring acoustic properties in ducts
Authors: Newman Timothy J. , Agarwal Anurag , Dowling Ann P. , Desvard Ludovic , Stimpson Ryan
Published: May 2013

An accurate description of sound propagation in a duct is important to obtain the sound power radiating from a source in both near and far fields. A technique has been developed and applied to decompose higher-order modes of sound emitted into a duct. Traditional experiments and theory based on two-sensor methods are limited to the plane-wave contribution to the sound field at low frequency. Due to the increase in independent measurements required, a computational method has been developed to simulate sensitivities of real measurements (e.g., noise) and optimize the set-up. An experimental rig has been constructed to decompose the first two modes using six independent measurements from surface, flush-mounted microphones. Experiments were initially performed using a loudspeaker as the source for validation. Subsequently, the sound emitted by a mixed-flow fan has been investigated and compared to measurements made in accordance with the internationally standardized in-duct fan measurement method. This method utilizes large anechoic terminations and a procedure involving averaging over measurements in space and time to account for the contribution from higher-order modes. The new method does not require either of these added complications and gives detail about the underlying modal content of the emitted sound.
Object selection by head aim and acoustic gaze in the big brown bat
Authors: Gaudette Jason , Kloepper Laura , Simmons James
Published: May 2013

Echolocating bats use their active sonar to locate, discriminate, and capture flying prey. A special challenge is tracking and pursuing a discrete moving object, sometimes in cluttered surroundings. Bats rely on head aim to follow their prey’s location throughout an entire capture sequence. By directing the sound emission organ (mouth or noseleaf) and thus acoustic gaze toward the target, the prey is kept on the main broadcast axis with the flattest incident spectrum. Although bats can perform head-aim tracking with an accuracy of a few degrees, we have explored the dynamics of the transmitted beam during tracking and its impact on angular precision. We measured head aim and acoustic gaze in the big brown bat (Eptesicus fuscus) with a 224-element microphone array. This array allows for fine scale, independent measurements of the beam across many frequencies with a high signal-to-noise ratio. Bats were trained to track moving real and electronic targets, and the head aim and acoustic gaze were recorded. We specifically examined the possibility that bats move different frequencies of their beam at different angular rates, with particular attention to the harmonics of the broadcasts. [Work supported by ONR, NSF, and NUWCDIVNPT.]
Dolphin echolocation is not seeing with sound
Authors: Harley Heidi E. , Fellner Wendi , Losch Barbara
Published: May 2013

Dolphin echolocation is often described as “seeing with sound;” however, vision and audition vary substantially in terms of direct access to spatial information. This study investigated spatial representation based on echoic information by having a dolphin match objects that varied only in shape. Stimulus sets (3 objects each) included unfamiliar objects made from (1) the same PVC parts (controlled sets), (2) different PVC parts (uncontrolled sets), or (3) non-PVC junk objects (junk sets). Sets were presented for 5 18-trial sessions in each of two conditions: an echoic condition (objects underwater with dolphin eyecups occluding vision) and a visual condition (objects in air). Performance accuracy varied across set type and condition. Worst was echoic controlled (12 sets, M = 45%) followed by echoic uncontrolled (12 sets, M = 50%). Visual performance was significantly better: controlled (M = 67%), uncontrolled (M = 76%). Echoic performance ranged from 32% to 86% across sets; visual performance from 50% to 100%. In contrast, performance accuracy with junk sets was higher echoically (2 sets, M = 81%) than visually (2 sets, M = 58%). Shape does not appear to be easily accessible to dolphins via echolocation, although it is accessible through vision. Dolphins integrate information about objects across modalities; they likely gain most shape information through vision.
Non-invasive delivery of small interfering ribonucleic acid for reduction of Huntingtin expression in the brain is achieved using focused ultrasound to disrupt the blood-brain barrier
Authors: Burgess Alison , Huang Yuexi , Querbes William , Sah Dinah W. , Hynynen Kullervo
Published: May 2013

Huntington’s disease is caused by a mutation in the Huntingtin (Htt) gene, which leads to neuronal dysfunction and cell death. Silencing of the Htt gene can halt or reverse the progression of the disease indicating that RNA interference is the most effective strategy for disease treatment. However, small interfering RNA (siRNA) does not cross the blood-brain barrier and therefore delivery to the brain is limited. Here, we demonstrate that focused ultrasound (FUS), combined with intravascular delivery of microbubble contrast agent, was used to locally and transiently disrupt the BBB in the right striatum of adult rats. 48 hours following treatment with siRNA, the right (treated) and left (control) striatum was dissected and analyzed for Htt mRNA levels. We demonstrate that FUS can non-invasively deliver siRNA-Htt directly to the striatum leading to a significant reduction of Htt expression in a dose dependent manner. Furthermore, we show that reduction of Htt with siRNA-Htt was greater when the extent of BBB disruption was increased. This study demonstrates that siRNA treatment for knockdown of mutant Htt is feasible without the surgical intervention previously required for direct delivery to the brain. Non-invasive delivery of siRNA through the blood-brain barrier (BBB) would be a significant advantage for translating this therapy to HD patients.
Physical mechanisms responsible for bubble translation near an interface
Authors: Tengelsen Daniel R. , Hay Todd , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: May 2013

Previous models and experiments have shown that direction of bubble translation near a viscoelastic layer depends on both the standoff distance of the bubble and the elastic properties of the layer. Here the individual forces due to the incident sound field and the field reflected from the viscoelastic layer are shown to compete with one another and ultimately determine the direction of bubble translation. In addition, many other factors pertinent to the direction of bubble translation such as the incident acoustic waveform, the phase and propagation direction of the incident field, and the radial bubble dynamics are considered. The force due to the viscoelastic layer is calculated using a Green’s function, which takes into account elastic waves and viscosity in the layer and the viscous boundary layer at the solid-liquid interface. [Work supported by the ARL:UT McKinney Fellowship in Acoustics and NIH DK070618.]
Ultrasonic bubbles in microfluidics for red blood cells, bacteria, and yeast lysis
Authors: Ohl Siew-Wan , Tandiono Tandiono , Ow Dave Siak-Wei , Klaseboer Evert , Choo Andre Boon-Hwa , Ohl Claus-Dieter
Published: May 2013

A custom microfluidic ultrasound device has been designed and implemented to efficiently create oscillating ultrasonic bubbles. These bubbles interact with the red blood cells, bacteria (Escherichia coli), and yeast (Pichia pastoris). Observations using high speed photography show that the red blood cells were strongly stretched. A numerical model using the Boundary Element Method is used to simulate the oscillating bubble's interaction with a nearby elastic pocket (a red blood cell model). Complex dynamics are discussed. Our ultrasonic microfluidic device is efficient in lysing E. coli and yeast cells for the harvesting of active intracellular content. Complete lysis of E. coli takes only 0.4 s while it takes about 1 s for the yeast cell. Temperature rise is minimal. We perform fluorescent intensity measurement and qRT-PCR (real-time polymerase chain reaction) to show that the functional integrity of the proteins and DNA is preserved.
Variations of temperature distribution and lesion formation induced by tissue inhomogeneity for therapeutic ultrasound
Authors: Zhang Dong
Published: May 2013

High intensity focused ultrasound (HIFU) has shown potential applications in therapeutic medical fields. This work reported both theoretical and experimental investigations on the influence of tissue inhomogeneity on the temperature distribution and tissue lesion formation using the phase screen model. The inhomogeneous tissue is considered as a combination of a homogeneous medium and a phase aberration screen. Numerical simulations were performed by using the nonlinear acoustic equation and bio-heat transfer equation. Four polyethylene (PE) plates with various standard deviations were made to mimic the inhomogeneity induced by human body abdominal. Temperature rise and lesion formation induced by HIFU were measured and compared with the numerical calculations. Results indicate that the standard deviation is associated with the focusing capability and temperature field observably. This study provides a theoretical and experimental basis for the development of precise HIFU treatment plan.
The origins of nonlinear enhancement in ex vivo tissue during high intensity focused ultrasound ablation
Authors: Jackson Edward , Cleveland Robin O. , Coussios Constantin C.
Published: May 2013

Thermal ablation by high intensity focused ultrasound (HIFU) is an emerging technique for non-invasive treatment of tumors. One barrier to its wider use is that current imaging modalities are not able to directly monitor changes in the tissue during treatment. Nonlinear imaging has been suggested as a possible mode, but it is unclear whether the nonlinear enhancement is due to changes in the properties of treated tissue or cavitation. This study uses a finite-amplitude insertion technique to measure B/A of ex-vivo bovine liver as a function of temperature. The technique creates quasi-plane wave conditions by measuring the waveform in the near field of a 10 cm diameter 1 MHz unfocused source. The linear acoustic properties are measured in the same location and then B/A determined by fitting data to a numerical solution of the Burgers equation. Measurements are taken during heating in a water bath (at a slow rate) and HIFU exposure (at a fast rate). Cavitation is monitored during the HIFU exposures. Previous data suggested B/A doubles after heating. However, in these experiments, the changes were less than 20%. These data suggest that cavitation effects dominate changes in B/A.