bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards an analytical derivation of a computational auditory masking model
Authors: Buchholz Joerg M.
Published: September 2013

Due to the fact that the signal processing underlying auditory masking is highly nonlinear, existing auditory masking models are usually designed on rather a trial-and-error basis than in a well-defined analytical way. Employing a model structure, which is based on the concept of signal-dependent compression (SDC), a method is presented which demonstrates the analytical derivation of a computational auditory masking model. Given the SDC-based model approach, analytical approximations of the model’s masked threshold simulations can be derived, which can directly be compared to masking functions known from the relevant literature. In this way, the present model structure has been adjusted in order to describe mainly two masking functions: (i) Webber’s law, which approximates the masker level dependency of simultaneous noise-on-tone masking, and (ii) a function proposed by Jestead et al., J. Acoust. Soc. Am. 71, 950–962 (1982), which approximates the masker level and test-signal delay dependency of forward masking. The practical applicability of the derived model structure has been verified by comparing model simulations to various known psychoacoustical data of simultaneous masking and forward masking for broadband noise masking tones.
Modeling the detection and level discrimination of tones in the presence of masking noise
Authors: Zhang Xuedong , Carney Laurel H.
Published: September 2013

The performance of three model detectors was evaluated for masked detection and level discrimination of tones in noise with different bandwidths and in a roving level paradigm (Kidd et al., 1989). The model detectors were based on (1) the output energy of several auditory filters tuned to different frequencies, (2) the envelope statistics (peakiness) of the auditory filter outputs, and (3) the cross-correlations between auditory-nerve (AN) fibers in a population model. The energy-based model predicted detection thresholds, but failed to predict masked level discrimination; this detector was robust for roving-levels in the wideband condition by combining information from different auditory filter outputs and the prediction was affected by roving narrow-band masker levels. Thresholds of the envelope-based detector were worse than human thresholds for some conditions; however, this model was robust in roving-levels for both wideband and narrow-band maskers. The monaural cross-correlation detector included model cells that were sensitive to temporal cues in model AN inputs in response to wideband noise and also included cells that were sensitive to input level changes. This model naturally combined rate and temporal information and predicted performance for both masked detection and discrimination. [Work supported by NIDCD R01-01641.]
Determination of noise and vibration impacts of construction and operation of the Second Avenue Subway
Authors: Pristera Jessica L.
Published: September 2013

An acoustical study was conducted to determine the potential for airborne noise and ground-borne noise and vibration impacts generated by construction and operation of the Second Avenue Subway. The study was performed in support of an environmental impact statement (EIS) that defined the areas along the proposed Second Avenue Subway corridor where any significiant impacts would occur as a result of construction activity and operation of the Second Avenue Subway. Using FTA guideline procedures, project-generated noise levels from subway construction and operations were determined. Construction noise levels exceeded operational noise levels. With limited alternative construction methods, practical mitigation methods were determined to reduce impacts.
Update on Chicago Transit Authority noise, how the city is attacking the problem
Authors: McDuffee Matthew , Cheenne Dominique
Published: September 2013

Chicago’s light rail rapid transit system is known as the L. The city of Chicago has the oldest standing tracks in the country with some portions of the system dating back to the 1880s. The noise of the L is a signature mark of Chicago and has long been dealt with by residents due to the integral nature of the transportation system to the city. The paper outlines what the CTA (Chicago Transit Authority) planning and development office defines as the four major sources of noise, and how they deal with the issues. Among these are thump, roar, rumble, and squeal. These issues are dealt with through rail grinding programs, wheel truing, and structural improvements, as well as wheel dampening rings, rail lubrication, and reconstruction projects to reduce the steepness of curves. A before and after study of one of the recent CTA construction projects was done to see if these goals are being met by the reconstruction projects being performed in the field. The CTA has agreed to cooperate with me in this project; the Vice President of planning and development has offered data and the CTA approval of the independent study.
Segments and segmental properties in cross-language perception: Korean perception of English obstruents in various prosodic locations
Authors: de Jong Kenneth , Silbert Noah , Park Hanyong
Published: September 2013

Experimental models of cross-language perception and second-language acquisition (such as PAM and SLM) typically treat language differences in terms of whether the two languages share phonological segmental categories. Linguistic models, by contrast, generally examine properties which cross classify segments, such as features, rules, or prosodic constraints. Such models predict that perceptual patterns found for one segment will generalize to other segments of the same class. This paper presents perceptual identifications of Korean listeners to a set of voiced and voiceless English stops and fricatives in various prosodic locations to determine the extent to which such generality occurs. Results show some class-general effects; for example, voicing identification patterns generalize from stops, which occur in Korean, to nonsibilant fricatives, which are new to Korean listeners. However, when identification is poor, there are clear differences between segments within the same class. For example, in identifying stops and fricatives, both point of articulation and prosodic position bias perceptions; coronals are more often labeled fricatives, and syllable initial obstruents are more often labeled stops. These results suggest that class-general perceptual patterns are not a simple consequence of the structure of the perceptual system, but need to be acquired by factoring out within-class differences.
Information and data real time transmission acoustic underwater system: TRIDENT
Authors: Trubuil Joel , Labat Joel , Lapierre Gerard
Published: September 2013

The objective of the Groupe d’Etudes Sous-Marines de l’Atlantique (GESMA) is to develop a robust high data rate acoustic link. A real-time receiver recently developed at ENST Bretagne has just been designed to cope with all perturbations induced by such harsh channels. In order to cope with channel features, a spatio-temporal equalizer introduced by J. Labat et al. [Brevet FT no. 9914844, ‘‘Perfectionnements aux dispositifs d’galisation adaptative pour recepteurs de systemes de communications numriques,’’ Nov. 1999] was recently implemented and evaluated. This equalizer is the core of the receiver platform [Trubuil et al., ‘‘Real-time high data rate acoustic link based on spatio temporal blind equalization: the TRIDENT acoustic system,’’ OCEANS 2002]. This paper provides an overview of this project. The context of the study and the design of high data rate acoustic link are presented. Last Brest harbor experiments (2002, 2003) are described. The real time horizontal acoustic link performances are evaluated. Two carriers frequencies are available (20, 35 kHz). Acoustic communications for bit rate ranging from 10 to 20 kbps and for channel length (shallow water) ranging from 500 to 4000 m have been conducted successfully over several hours.
High-rate acoustic link for underwater video transmission using differential amplitude phase shift keying (DAPSK)
Authors: Pelekanakis Costas , Stojanovic Milica , Freitag Lee
Published: September 2013

A high bit-rate acoustic link for underwater video transmission is examined. Currently, video encoding standards allow video transmission at bit rates on the order of 64 kbps. To provide an acoustic transmission capability that meets this bit-rate requirement, we focus on the use of high-level bandwidth-efficient modulation methods. We consider the use of 16-, 32-, and 64-differential amplitude and phase shift keying (DAPSK) with varying number of amplitude levels. DAPSK does not require explicit carrier phase synchronization at receiver, but instead relies on differentially coherent detection. It thus represents an alternative to conventional quadrature amplitude modulation (QAM) methods, whose high-level constellations are sensitive to phase distortion induced by the channel. System performance is demonstrated experimentally, using 25000 symbols/s at a carrier frequency of 75 kHz over a short vertical path. Excellent results were obtained, thus achieving bit rates as high as 150 kbps, which are sufficient for real-time transmission of compressed video.
Using ocean ambient noise for array element localization
Authors: Sabra Karim G. , Roux Philippe , Kuperman W. A. , Hodgkiss W. S. , D’Spain Gerald L.
Published: September 2013

Time delays, associated with the direct and surface reflected arrivals, between the elements of a bottom hydrophone array can be extracted using ambient noise cross correlations [Sabra et al., J. Acoust. Soc. Am. 114, 2462 (2003)]. This is confirmed using long-time noise recordings that were collected in May 1995 near the S. California coast at an average depth of 21 m. The noise is mainly biological in the frequency range of 350–700 Hz [D’Spain et al., J. Acoust. Soc. Am. 99, 2453 (1996)]. These coherent wavefront arrivals across the array’s aperture are used for array element localization.
Ambient noise effects on towed-array search optimization
Authors: DelBalzo Donald R. , Rike Erik R.
Published: September 2013

Oceanographic and acoustic conditions in littoral environments are extremely complex and dynamic. Spatial and temporal variability of low-frequency signal and noise fields destroys the basic homogeneous assumptions associated with standard tactical search concepts, like simple ladder patterns. Genetic algorithms have recently been applied to the signal part of this problem [D. P. Kierstead and D. R. DelBalzo, ‘‘A genetic algorithm approach for planning search paths in complicated environments,’’ Military Operations Research Journal (March/April 2003)] to produce near-optimal, nonstandard search tracks that maximize probability of detection in uniform noise fields. In a complex environment, an optimal search plan will also depend on the spatial and temporal properties of AN. The dynamic ambient noise model (DANM) was used to produce low-frequency directional noise fields, based on discrete ship tracks. Then, optimal genetic search tracks were calculated for towed arrays, in the midst of spatial variability and temporal fluctuations of noise. The results show the importance of careful consideration of AN when designing optimum tactics. [Work sponsored by NAVSEA under the LCS project.]
Analysis on vertical directivity of shallow-water ambient noise in South China Sea
Authors: Wei Ruey-Chang , Chan Hsiang-Chih , Lin Po-Chang
Published: September 2013

Beamforming is used to analyze the vertical directivity of the low-frequency ambient noise in shallow water. The data were measured by the vertical line array (VLA) of the Asian Seas International Acoustics Experiment (ASIAEX), from 3 May to 16 May 2001, and three frequencies, 200, 400, and 800 Hz, were studied. The results of the calculation show that the sound source of 200 and 400 Hz is from the horizontal direction and contributed by distant shipping, and the source of 800 Hz is mainly from high grazing angle that generated from surface noise. The well-known noise notch was also found in the study; the low-angle energy reflections from surface and bottom are the function of frequency, sound-speed profile, bathymetry, and the noise distribution. The time fluctuation of the noise notch is shown and correlated with oceanographic changes. The influences of internal wave and pass typhoon Cimaron during the experiment are significant too on vertical directivity of ambient noise.
Application-driven design of auralization systems
Authors: Begault Durand R.
Published: September 2013

Acoustical environmental simulation (auralization) involves rendering a binaural signal that articulates simultaneously the positional information of a sound source and the source’s acoustic and vibratory interaction with its environmental context. This places significant challenges on both the modeling and rendering components of such a system. Overcoming real-time limitations of processors can be accomplished by implementing rendering limits based on auditory threshold data for both early reflections and late reverberant energy. However, final assessment of system quality is dependent on the specific task or goal of the simulation. The use of auralization in accomplishing a telerobotic task requires head tracking and low latency, while environmental cues such as obstacles with acoustic reflections can be simplified and exaggerated beyond veridical representation. Contrasting this is the task of assessing speech intelligibility of an emergency public address system, or the quality of a space for musical performance, requiring a more accurate level of simulation of acoustical materials and sound-source characteristics. Modeling accuracy is complicated by such factors as the level of variance in the absorptive and diffusive properties of materials in terms of their real-world application. Assessment of auralization quality must therefore involve a best estimate of significant factors for a particular application.
Investigation of the optimum acoustical conditions for speech using auralization
Authors: Yang Wonyoung , Hodgson Murray
Published: September 2013

Speech intelligibility is mainly affected by reverberation and by signal-to-noise level difference, the difference between the speech-signal and background-noise levels at a receiver. An important question for the design of rooms for speech (e.g., classrooms) is, what are the optimal values of these factors? This question has been studied experimentally and theoretically. Experimental studies found zero optimal reverberation time, but theoretical predictions found nonzero reverberation times. These contradictory results are partly caused by the different ways of accounting for background noise. Background noise sources and their locations inside the room are the most detrimental factors in speech intelligibility. However, noise levels also interact with reverberation in rooms. In this project, two major room-acoustical factors for speech intelligibility were controlled using speech and noise sources of known relative output levels located in a virtual room with known reverberation. Speech intelligibility test signals were played in the virtual room and auralized for listeners. The Modified Rhyme Test (MRT) and babble noise were used to measure subjective speech intelligibility quality. Optimal reverberation times, and the optimal values of other speech intelligibility metrics, for normal-hearing people and for hard-of-hearing people, were identified and compared.
Acoustic behavior of echolocating bats in complex environments
Authors: Moss Cynthia , Ghose Kaushik , Jensen Marianne , Surlykke Annemarie
Published: September 2013

The echolocating bat controls the direction of its sonar beam, just as visually dominant animals control the movement of their eyes to foveate targets of interest. The sonar beam aim of the echolocating bat can therefore serve as an index of the animal’s attention to objects in the environment. Until recently, spatial attention has not been studied in the context of echolocation, perhaps due to the difficulty in obtaining an objective measure. Here, we describe measurements of the bat’s sonar beam aim, serving as an index of acoustic gaze and attention to objects, in tasks that require localization of obstacles and insect prey. Measurements of the bat’s sonar beam aim are taken from microphone array recordings of vocal signals produced by a free-flying bat under experimentally controlled conditions. In some situations, the animal relies on spatial memory over reflected sounds, perhaps because its perceptual system cannot easily organize cascades of echoes from obstacles and prey. This highlights the complexity of the bat’s orientation behavior, which can alternate between active sensing and spatial memory systems. The bat’s use of spatial memory for orientation also will be addressed in this talk. [Work supported by NSF-IBN-0111973 and the Danish Research Council.]
Dolphin and bat sonar: Convergence, divergence, or parallelism
Authors: Ketten Darlene R. , Simmons James , Hubbard Allyn E. , Mountain David A.
Published: September 2013

During the explosive period of mammalian radiation, two groups emerged with highly effective biosonar systems, bats and toothed whales. In the intervening 50 million years, these groups evolutionarily honed their hearing for operation in radically different media. This paper addresses what functional aspects the media influenced in the biosonar receptors of bats versus dolphins by comparing the auditory peripheries of these groups. Data were obtained using thin-section microscopy, CT imaging, and inner-ear models. Inner-ear anatomy is fundamentally similar in these animals, although differences exist in both neural density and distribution in each group. Specialist ears are present in both groups, suggesting at least one odontocete species has cochlear specializations consistent with CF-FM bats, including specialized basilar-membrane regions and high-frequency neural foveal areas. Cochlear specializations in both groups are primarily linked to peak spectra of sonar signals, may expand frequency representation, and may enhance tuning in adjacent ear segments by generating standing wave phenomena. Most differences, such as the soft-tissue external ear analogs in odontocetes, are clearly media driven. Other differences among species within each group are correlated with signal type or habitat complexity. [Work supported by Mellon Foundation; Seaver Institute; ONR.]
How bats’ ears probe space: A numerical analysis of pinna shapes
Authors: Müller Rolf , Hallam John C. T. , Peremans Herbert , Streicher Alexander , Lerch Reinhard
Published: September 2013

Like any antenna, bat pinnae have directivity patterns which impose a frequency-dependent sensitivity weighting on possible locations of sonar targets. Here, numerical predictions of such directivities are presented. The predictions are based on finite-element meshes generated from computer-tomographic cross-section images of pinna samples obtained from several bat species. A time-domain finite-element model was combined with a near-field to far-field transformation to yield high-resolution directivity estimates. The data obtained enable the introduction of new visualization approaches to the study of bat biosonar. These techniques portray the spatial and frequency dimension of the patterns, facilitate quantitative analysis, and reveal functional properties relevant to specific sensing tasks, like scanning the surface of an extended target. The computer graphics representations of the pinna shapes (voxel arrays, volume and surface meshes) can be readily manipulated to shed light onto how the observed properties arise. For example, appendages have been removed by ‘‘Boolean surgery’’ or altered in orientation or shape by standard computer graphics transformations. The results of these manipulations are compared with respect to wave-field amplitudes as well as with respect to directivity patterns. [Work supported by the European Union (CIRCE Project, IST-2001-35144).]
Digital neuromorphic processing for a simplified algorithm of ultrasonic reception
Authors: Qiang Lin , Clarke Chris
Published: September 2013

Previously, most mammalian auditory systems research has concentrated on human sensory perception whose frequencies are lower than 20 kHz. The implementations almost always used analog VLSI design. Due to the complexity of the model, it is difficult to implement these algorithms using current digital technology. This paper introduces a simplified model of biosonic reception system in bats and its implementation in the ‘‘Chiroptera Inspired Robotic CEphaloid’’ (CIRCE) project. This model consists of bandpass filters, a half-wave rectifier, low-pass filters, automatic gain control, and spike generation with thresholds. Due to the real-time requirements of the system, the system employs Butterworth filters and advanced field programmable gate array (FPGA) architectures to provide a viable solution. The ultrasonic signal processing is implemented on a Xilinx FPGA Virtex II device in real time. In the system, 12-bit input echo signals from receivers are sampled at 1 M samples per second for a signal frequency range from 20 to 200 kHz. The system performs a 704-channel per ear auditory pipeline operating in real time. The output of the system is a coded time series of threshold crossing points. Comparing hardware implementation with fixed-point software, the system shows significant performance gains with no loss of accuracy.
The whistles of bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico
Authors: Bazua-Duran Carmen
Published: September 2013

This work presents the description and geographic comparison of whistles from bottlenose dolphins recorded in three coastal areas in the northwestern Gulf of Mexico (Galveston and Corpus Christi Bays and Madre Lagoon), one oceanic area in the northern Gulf, and one coastal area in the southern Gulf (Terminos Lagoon). The 1499 whistle contours analyzed were categorized into 289 whistle types, of which 120 types were unique to a specific area. From the remaining 169 types, more types were common between Madre and Corpus Christi than between Galveston and either Corpus Christi or Madre, results in agreement with the dolphin mixing patterns between these three areas. Whistles from the oceanic area were more similar to those of Madre, suggesting that contact between coastal and oceanic dolphins in the northwestern part of the Gulf may be through Madre Lagoon. Terminos and Galveston whistles, the areas furthest apart, were very similar, indicating that contact between dolphin groups may not be the only parameter determining whistle repertoire similarities. Dolphin whistle similarities may also depend on comparable habitat use and population structure. The new signal type curve shows that more than 250 whistles are needed for each area in order to adequately describe the whistle repertoire.
Model-based localization and tracking of marine mammals
Authors: Abawi Ahmad T. , Porter Michael B. , Siderius Martin , Hildebrand John , Wiggins Sean
Published: September 2013

Data from the August 2003 experiment conducted by the Scripps Institution of Oceanography in the Southern California Offshore Range (SCORE) are used to localize and track marine mammals. SCORE is a naval training area near the island of San Clemente located in relatively shallow water. The water depth where the experiment was conducted is around 360 m. Data were recorded on a 100-m, eight-element vertical array deployed from the Floating Instrument Platform (FLIP) and four bottom-mounted seismometers deployed in an area covering approximately three square kilometers. During the course of the 7-day experiment continuous recording of the ocean environment was made. The recordings contain numerous blue and fin whale calls. Matched field processing was used on the vertical array data to localize and track singing whales. The differences between different animal calls (extended, low frequency calls in the case of blue whales and short, impulsive calls in the case of fin whales) are exploited to track different animal species. Animals were also independently tracked by comparing the predicted (computed using a propagation model) and measured difference in time of arrival recorded in each seismometer pairs. The tracking results obtained from the two techniques are compared.
Iteration of ultrasound aberration correction methods
Authors: Maasoey Svein-Erik , Angelsen Bjoern , Varslot Trond
Published: September 2013

Aberration in ultrasound medical imaging is usually modeled by time-delay and amplitude variations concentrated on the transmitting/receiving array. This filter process is here denoted a TDA filter. The TDA filter is an approximation to the physical aberration process, which occurs over an extended part of the human body wall. Estimation of the TDA filter, and performing correction on transmit and receive, has proven difficult. It has yet to be shown that this method works adequately for severe aberration. Estimation of the TDA filter can be iterated by retransmitting a corrected signal and re-estimate until a convergence criterion is fulfilled (adaptive imaging). Two methods for estimating time-delay and amplitude variations in receive signals from random scatterers have been developed. One method correlates each element signal with a reference signal. The other method use eigenvalue decomposition of the receive cross-spectrum matrix, based upon a receive energy-maximizing criterion. Simulations of iterating aberration correction with a TDA filter have been investigated to study its convergence properties. A weak and strong human-body wall model generated aberration. Both emulated the human abdominal wall. Results after iteration improve aberration correction substantially, and both estimation methods converge, even for the case of strong aberration.
Enhanced detection of acousto-photonic imaging signals using a photorefractive crystal based system
Authors: Sui Lei , Murray Todd , Maguluri Gopi , Nieva Alex , Blonigen Florian , DiMarzio Charles , Roy Ronald A.
Published: September 2013

Acousto-photonic imaging is a dual-wave sensing technique where diffuse coherent light wave interacts with a superimposed acoustic field. A phase-modulated light wave emanates from the interaction region and carries with it information about the local opto-mechanical properties of the insonated media. The coherent nature of the light produces a speckle field. The modulation of the speckle field is spatially incoherent, yielding a small modulation depth when collecting multiple speckles or extremely low light levels when detecting at the single speckle level. We report preliminary results from a new detection scheme where the scattered laser light is mixed with a reference beam in a photorefractive crystal. The crystal serves as a dynamic holographic medium and a photorefractive grating is formed from which the reference beam diffracts. The diffracted reference beam has the same spatial structure as the scattered light, and the two interfere at the photodetector where the phase modulation on the scattered beam is converted to an intensity modulation. Measurements of the signals are presented for gel phantoms seeded with suspended polystyrene beads. The results exhibit qualitative agreement with a simple theoretical model. [Work supported by the Center for Subsurface Sensing and Imaging Systems via NSF ERC Award No. EEC-9986821.]
Validation of Doppler ultrasound measurements using particle, image velocimetry in a flow phantom
Authors: Cosgrove John , Meagher Siobhan , Hoskins Peter , Greated Clive , Black Richard
Published: September 2013

Cardiovascular disease is responsible for over 50% of all deaths in the world and there is a substantial amount of evidence which suggests that abnormal vessel wall shear stress is correlated with the development of atherosclerosis. Wall shear stress is calculated from wall shear rates, the measurement of which is a technically challenging problem for ultrasound. In this study a flow phantom consisting of a meshed-gear pump and corresponding control electronics is used to generate a range of flow waveforms in a straight tube. These flows are measured using Doppler ultrasound and compared to corresponding particle image velocimetry (PIV) measurements and to analytical solutions of the flow equations for a range of Wormersley parameters. Although previous studies have been undertaken calibrating Doppler ultrasound in straight tubes, they have not used PIV. This study serves as a prelude to investigations using PIV to assess the accuracy of Doppler ultrasound in phantoms with anatomically realistic geometries for which there are no analytical solutions to the flow. [Research funded by the Engineering and Physical Sciences Research Council UK.]
In vitro microscopic imaging of rt-PA thrombolysis with 120-KHz ultrasound in a human clot model
Authors: Cheng Jason Y. , Holland Christy K. , Shaw George J.
Published: September 2013

Substantial enhancement of recombinant tissue plasminogen activator (rt-PA) thrombolysis can be achieved with diagnostic frequency ultrasound. Microscopic visualization of human whole-blood clots treated with human fresh frozen plasma (HFFP), rt-PA, and 120-KHz pulsed ultrasound offers a useful method to study the possible mechanisms. Whole human-blood clots were formed inside of glass micropipette (1.7-mm diameter) and placed in a water tank at 37°C. The clot–plasma interface was imaged using an inverted optical microscope. Clots were exposed to HFFP (control), HFFP and rt-PA (0.0945 mg/ml), (sham), or HFFP, rt-PA (0.0945 mg/ml), and 120-KHz pulsed ultrasound (ultrasound treated) for 30 min. Thrombolysis at the clot surface was recorded with a CCD camera and the lytic front was analyzed as a function of time. Images of the clots were analyzed to quantify the overall amount of lysis and compared to a dynamic chemical model of enzymatic degradation in the presence of ultrasound-induced flow. Sham and ultrasound-treated clots showed significant lysis with the lytic rate of (1.33±0.02 microns/min; mean ± s.d.) and (5.17±0.10 microns/min), respectively. Ultrasound enhanced thrombolysis by a factor of 4. In addition, the lytic rate profile may offer a suggestion to the mechanism of enhancement. No thrombolysis was observed in control clots. [The authors of this study gratefully acknowledge the support of the Whitaker Foundation Grant RG-0128-01.]
Ultrasonic brain therapy: First trans-skull in vivo experiments on sheep using adaptive focusing
Authors: Pernot Mathieu , Aubry Jean-Francois , Tanter Michael , Fink Mathias , Boch Anne-Laure , Kujas Michèle
Published: September 2013

A high-power prototype dedicated to trans-skull therapy has been tested in vivo on 20 sheep. The array is made of 200 high-power transducers working at 1-MHz central and is able to reach 260 bars at focus in water. An echographic array connected to a Philips HDI 1000 system has been inserted in the therapeutic array in order to perform real-time monitoring of the treatment. A complete craniotomy has been performed on half of the treated animal models in order to get a reference model. On the other animals, a minimally invasive surgery has been performed thanks to a time-reversal experiment: a hydrophone was inserted at the target inside the brain thanks to a 1-mm2 craniotomy. A time-reversal experiment was then conducted through the skull bone with the therapeutic array to treat the targeted point. For all the animals a specified region around the target was treated thanks to electronic beam steering. Animals were finally divided into three groups and sacrificed, respectively, 0, 1, and 2 weeks after treatment. Finally, histological examination confirmed tissue damage. These in vivo experiments highlight the strong potential of high-power time-reversal technology.
On the potential performance of micro-fabricated subminiature microphones based on electron surface tunneling
Authors: Pedersen Michael
Published: September 2013

The principle of electron tunneling across a vacuum potential energy barrier, as utilized in surface tunneling microscopy (STM), is a well known, highly sensitive, method for the detection of surface features and displacements in the subnanometer regime. In this paper, the basic properties of the surface tunneling principle and its possible utilization in acoustic sensors are discussed, with particular focus on the expected noise properties of a microphone based on tunneling in comparison to more conventional devices based on capacitive detection. It is found that the noise performance is largely limited by thermal noise due to the acoustical radiation impedance of the device in combination with electronic noise in the circuit used to establish and control the tunneling current. Finally, possible methods for sensor fabrication are discussed with special attention aimed at resolving the common problem of vibration sensitivity associated with STM. This problem stems from the relative large inertial mass and low flexural rigidity of the tunneling tip suspension system in most detector designs. Alternative approaches suitable for acoustic sensors in which the tunneling tip is fixed are described and it is shown that low vibration sensitivities comparable to capacitive devices can be achieved.
Effects of coupled vibrations in cylindrical shell transducers
Authors: Aronov Boris , Regmi Sundar , Brown David A.
Published: September 2013

Coupled vibrations in cylindrical transducers can have unwanted effects on the resulting radiation or reception of sound. An investigation of vibrations of piezoelectric cylindrical shell transducers using analytical and experimental methods shows the presence of an additional flexural resonant mode that was not previously reported [see J. F. Haskins and J. L. Walsh, ‘‘Vibrations of ferroelectric cylindrical shells with transverse isotropy,’’ J. Acoust. Soc. Am. 29, 6 (1957)]. The additional flexural mode can be strongly coupled to radial and axial modes in cylindrical shells with finite thickness. The effect can be substantial, resulting in unwanted resonances that may be in the frequency band of interest for both projectors and receivers. An equivalent circuit is derived, which describes the cylindrical transducer operation taking into account the effect of coupled vibrations. The results of calculations in terms of resonant frequencies and frequency responses for both transmit and receive modes are in good agreement with experiments. The overall performance of the cylindrical shell transducer can be greatly enhanced by using cylinders of appropriate height to diameter aspect ratio. [Work supported in part by ONR 321SS.]
Measurements of mutual radiation impedance in arrays of piezoelectric cylindrical shell transducers
Authors: Oishi Tetsuro , Aronov Boris S. , Brown David A.
Published: September 2013

We present our recent experimental results of the mutual radiation impedance of piezoelectric cylindrical shell transducers in arrays using the Z- and V-methods previously reported by the authors [J. Acoust. Soc. Am. 112, 2407 (2002)]. The mutual radiation impedance in an array of two coaxially aligned cylindrical transducers was determined as a function of separation distance. The results obtained by both methods are in good agreement with the calculations based on the analytical equations for a similar array developed by D. H. Robey [J. Acoust. Soc. Am. 27, 706–710 (1955)]. The mutual radiation impedances in other array geometries including planar and curved arrays of cylindrical shell transducers, in which there is no known analytical solution, were also measured by the same methods in our underwater test facility. [Work supported in part by ONR 321 SS.]
Digital filters for accurate simulation of wave propagation losses in tubes
Authors: Wilhelms-Tricarico Reiner , McGowan Richard
Published: September 2013

A boundary layer approximation for viscous damping in one-dimensional wave transmission in a tube results in an irrational frequency-dependent damping filter for sound propagation. This filter can be approximated with high accuracy by a rational filter function that can be obtained from Padé approximations or continued fraction expansion. Taking into account the viscous losses in a Kelly–Lochbaum structure that represents sound propagation in a tube with spatially varying cross section results in replacing the delay elements of the lattice filter for the loss-free case by special recursive filters. The design, implementation, and applications of the filter structures will be presented.
In-room sound reproduction using active control: Simulations in the frequency domain and comparison with wave field synthesis
Authors: Gauthier Philippe-Aubert , Berry Alain , Woszczyk Wieslaw
Published: September 2013

Active sound control simulations were performed for progressive sound field reproduction over a ‘‘large’’ area using multiple monopole loudspeakers. The model is limited to the simulation of the acoustical output of the prescribed loudspeaker array in a simple room, and is based on achieving an optimal control in the frequency domain. This rather simple approach is chosen for this first feasibility study concerning a limited number of possible configurations of sensing microphones and loudspeakers. Other issues of interest concern the comparison with wave field synthesis, the control mechanisms and transducer configurations. As it is demonstrated, in-room reproduction of sound field using active control can be achieved with a residual normalized squared error below 2% while open-loop wave field synthesis gives more than 100% of error in the same situation. Usage of active control technique suggests the possibility to automatically overcome the room’s natural dynamics. A special surrounding configuration of sensors is introduced for a sensor-free listening area. [Work supported by NSERC, NATEQ, VRQ, and Université de Sherbrooke.]
Synthesis of audio spectra using a novel Bessel expansion
Authors: Vijayakumar V. , Eswaran C.
Published: September 2013

It is shown in this paper that the intensity variations of an audio signal in the frequency domain can be expressed by using a novel mathematical function containing a series of weighted complex Bessel functions. By proper choice of values for two parameters, this function can transform an input spectrum of discrete frequencies of unit intensity into the known spectra of different musical instruments. Two specific examples of musical instruments are considered for evaluating the performance of this method. It is found that this function yields musical spectra with a good degree of accuracy. The proposed method is compared with known synthesis techniques such as FM, AFM, and DFM [J. M. Chowning, J. Audio Eng. Soc. 21, 526–534 (1973); Palamin et al., ibid. 36, 671 (1988); Tan, ibid. 42 (11), 918–926 (1994)]. A brief discussion on the physical basis for the derivation of the proposed function is also presented.
Leo Beranek’s contributions to architectural acoustics from development of criteria for design to practical applications in buildings of all types
Authors: Cavanaugh William J.
Published: September 2013

This paper traces Leo Beranek’s continuing contributions in architectural acoustics since the author joined the consulting staff of Bolt Beranek and Newman Inc. in February 1954. They are legion, including room acoustics, sound and vibration transmission, control of ambient noise from building mechanical electrical and plumbing systems, electrocoustic applications and other issues through the evaluation of the finished building spaces themselves. While Beranek’s classic texts, Acoustical Measurements (1948) and Acoustics (1954) served as essential references for the early BBN staff, criteria in architectural acoustics were severely limited if not nonexistent. If he did not take up the challenge to fill a criterion gap, his inspirational leadership guided others to do so, as it did the author and colleagues trying to better understand speech privacy in buildings. Beranek’s real labor of love in architectural acoustics is in understanding music performance halls. Beranek’s dedicated research over a span of five decades has produced countless journal papers in concert hall acoustics as well as three important texts, the most recent in 2003. Leo Beranek’s contributions have earned him the Sabine and Gold Medals of the Acoustical Society and countless other honors including most recently the National Medal of Science.
BBN and structural acoustics
Authors: Lyon Richard H.
Published: September 2013

Leo Beranek, Dick Bolt, and Bob Newman founded a company based on technical excellence and client service—BBN. The early services were oriented to noise control and architectural acoustics, but these led fairly quickly over about a decade into several related fields. One such field, now called ‘‘structural acoustics,’’ arose from activities in noise control where the radiated sound due to vibrations of the machine caused problems. Commercial work on such problems was later augmented by work for the US Navy, the Air Force, and NASA. In the mid- and late-1950s Ira Dyer built the group that during the course of about the next decade developed the field of structural acoustics, with emphasis on statistical modeling and with applications to ships, aircraft, and space launch vehicles. The author will present some of his personal remembrances of this second decade, with particular emphasis on the development of statistical energy analysis.
Books on acoustics
Authors: Shaw Neil A.
Published: September 2013

The legacy of a man is not limited to just his projects. His writings in many cases are a more lasting, and a definitely more accessible, monument. For 60 years, Leo L. Beranek has produced books on acoustics, acoustic measurements, sound control, music and architecture, noise and vibration control, concert halls, and opera houses in addition to teaching and consulting. His books are standard references and still cited in other books and in technical and professional articles. Many of his books were among, if not, the first comprehensive modern treatment of the subject and many are still foremost. A review of Dr. Beranek’s many books as well as some anecdotes about the circumstances and consequences of same will be presented.
Directional loudness of narrow-band noises in an anechoic sound field
Authors: Sivonen Ville P. , Ellermeier Wolfgang
Published: September 2013

In order to investigate the effect of sound incidence angle on loudness across a larger set of parameters than have been used in most previous studies, a listening experiment was carried out using a loudspeaker setup in an anechoic chamber. Eight subjects, whose absolute hearing thresholds and head-related transfer functions (HRTFs) were measured, participated in a total of 22 sessions each. On each trial their task was to judge which of two narrow-band noises sounded louder. These judgments were used in an adaptive procedure to find loudness matches between a frontal reference location and seven other sources, positioned both in the horizontal and median planes. Sound incidence angle, center frequency, and overall SPL were varied in the procedure. The results show that loudness is not constant over sound incidence angles, with matches varying over a range of 10 dB, and showing considerable frequency dependency. The pattern of results also varies substantially between subjects, but can be accounted for by interindividual variations in the listeners’ HRTFs. [Work Kjær Sound & Vibration Measurement A/S.]
How do listeners detect interaural incoherence?
Authors: Goupell Matthew J. , Hartmann William M.
Published: September 2013

Listeners are remarkably sensitive to interaural incoherence. They can easily distinguish between a coherence of 1.00 and a coherence of 0.99. Interaural incoherence leads to the sensation of apparent source width; it is also held to be responsible for the masking level difference and for the creation of binaural pitch. However, incoherence per se is only a statistical description of signals; it is not indicative of any particular auditory binaural property. To discover the relevant binaural attribute(s), three-interval oddity experiments were performed using narrow-band noises that were perfectly coherent or slightly incoherent. The listener’s task was to identify the incoherent noise. First, it was shown that different frozen noises with identical values of incoherence could often differ greatly in detectability. Subsequent experiments studied the detectability of incoherent frozen noises that were were particularly strong or particularly weak according to selected binaural difference functions. These functions tested different rules for combining interaural phase differences (IPD) and interaural level differences (ILD)—either weighted sums of squares or rules that combine IPD and ILD to form a fluctuating lateralized image. The goal was to discover the best predictor of incoherence detectability. [Work supported by the NIDCD Grant DC 00181.]
Earedness: Left-eared and right-eared listeners
Authors: Hartmann William M. , Zhang Peter Xinya , Culling John F.
Published: September 2013

The Huggins pitch (HP) stimulus known as HP- is created with a broadband background noise having an interaural phase difference of zero, together with a narrow boundary region wherein the interaural phase varies with frequency. At the spectral center of the boundary region the interaural phase is 180 deg. Therefore, HP- is symmetrical with respect to the two ears. Despite the symmetry, most listeners hear the HP image strongly lateralized to one side of the head. Some hear it on the right; others hear it on the left. Two surveys, involving 51 listeners, found that these perceptions do not change when the headphones are reversed. Extensive experiments with five listeners found that the lateralization directions were usually insensitive to variations in the frequency of the boundary region (more than two octaves). The left or right preference was strong enough that listeners chose alias locations (differing from a more central location by 360 deg) on the preferred side when various frequency-independent interaural delays and phase shifts were added to the HP stimulus. The experiments suggest that given ambiguous stimuli, listeners exhibit earedness—a preference similar to, but not as strong as, handedness. [Work supported by the NIDCD Grant DC 00181.]
Psychophysical calibration of auditory range control in binaural synthesis with independent adjustment of virtual source loudness
Authors: Martens William L.
Published: September 2013

This paper reports the results of a study designed to evaluate the effectiveness of synthetic cues to the range of auditory images created via headphone display of virtual sound sources processed using individualized HRTFs. The particular focus of the study was to determine how well auditory range could be controlled when independent adjustment of loudness was also desired. Variation in perceived range of the resulting auditory spatial images was assessed using a two-alternative, forced choice procedure in which listeners indicated which of two successively presented sound sources seemed to be more closely positioned. The first of the two sources served as a fixed standard stimulus positioned using a binaural HRTF measured at ear level, 1.5 m from the listeners head at an azimuth angle of 120 deg. The second source served as a variable loudness comparison stimulus processed using the same pair of HRTFs, with the same interaural time difference but with a manipulated interaural level difference. From the obtained choice proportions for each pairwise comparison of stimuli, numerical scale values for auditory source range were generated using Thurstone’s Case IV method for indirect scaling. Results provide a basis for calibrated control over auditory range for virtual sources varying in loudness.