bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ fish school studies enabled by multi-beam sonar
Authors: Misund Ole Arve
Published: October 2013

Since multi-beam sonar became available to fisheries research applications in the seventies, much insight has been accumulated on metric aspects of fish schools as geometry, packing density, and school biomass. Behavioral aspects such as swimming speed, migration and avoidance of vessels and fishing gears have also been a focus. In later years, ecosystem aspects of fish school studies such as spatial distribution, influence of physical features and interactions with predators and prey have been quantified. An update is given on how the knowledge on these various aspects of fish schools have been collected by use of multi-beam sonar. Prospects for further insight in the role of fish schools in marine ecosystems are considered in the light of the technological development of multi-beam sonar that is now taking place. Both the development of recording instruments and post-processing systems are considered.
Hawaiian spinner dolphins aggregate midwater food resources through cooperative foraging
Authors: Benoit-Bird Kelly , Au Whitlow
Published: October 2013

To test the hypothesis that spinner dolphins in Hawaii may actively aggregate their prey through cooperative foraging, a 200-kHz multi-beam sonar (Simrad MS2000) was used to observe 323 groups of spinner dolphins foraging within a midwater, micronekton sound-scattering layer off Oahu. Strong cooperation was observed in groups of 8–14 pairs of spinner dolphins. The dolphin group size was highest at midnight when the density of prey was highest and was significantly higher in Makua Beach, where the prey density was higher, than Electric Beach, where the prey density was lower. Cooperative groups of dolphins aggregated their food resources, apparently using their preys’ avoidance behavior to create distinct, high-density patches in the prey. Prey aggregation was strongly stereo-typed, regardless of the distribution of the scattering layer. Dolphins swam around the edge of a 28–40 m diameter circle at least 5 times, concentrating prey within this area before pairs of dolphins on opposite sides of the circle swapped positions in the circle, swimming through the high density prey ’donut’ they had formed. The hypothesis that nocturnal animals aggregate prey in midwater could not have been tested without the three-dimensional information on prey distribution and dolphin geometry provided by the multi-beam.
Schooling in pelagic fish: An approach in three dimensions using vertical scanning multibeam sonar
Authors: Paramo Jorge , Gerlotto Franois , Oyarzun Ciro
Published: October 2013

In fish resource assessment, it is very important to know about the behavior and the form in that schools are occupying the space. The present paper describes the morphology and internal structure in pelagic schools using vertical scanning multibeam sonar. This sonar provides with data making it possible to reconstruct the school in three-dimensions. Acoustic surveys were carried out in Venezuela, Senegal, and Mexico. Geometrical (position of the school), morphological, density and internal structure parameters were extracted from a total of 668 schools: 257 from Mexico, 343 from Venezuela, and 68 from Senegal. The analysis of fish schools avoidance effect caused by vessels showed two modes in school frequency distribution in the case of Venezuela and Senegal schools and three modes for Mexico schools. This frequency distribution was decreasing as a vessel distance increase. In general, the schools show an amoeboid shape, which cannot be simply described with some geometric volume (e.g., spheres or ellipsoids). Also, it shows a contagious internal structure, i.e., fishes are not positioned at random inside the school. Another interesting characteristic is the presence of empty spaces inside the school that are called vacuoles.
A hybrid model for the three-dimensional scattering from objects in underwater waveguides
Authors: Zampolli Mario , Burnett David S. , Jensen Finn B. , Schmidt Henrik , Blottman John B.
Published: October 2013

The scattering from objects in underwater waveguides is a multi-scale problem, involving both near-field effects in the vicinity of the scatterer as well as long-range propagation through the waveguide. To solve this problem, 3-D Finite-Element STructural Acoustics software developed at SACLANTCEN (FESTA) and an underwater waveguide propagation model based on wavenumber integration developed at MIT (3-D OASES), are coupled into a hybrid model. In a three-step method, the propagation model is used to compute the incident acoustic field in the vicinity of the target, which may be floating, proud, partially buried or buried in the sediment. The incident field data is subsequently passed as an input to the finite-element tool to compute the target-scattered acoustic nearfield. In the final step, the scattered field is propagated through the waveguide by OASES. A second method of coupling between the two models is based on the characterization of the target scattering via spherical harmonic basis responses. The advantage of the second method is that the finite-element computations need to be performed only once for each frequency, regardless of the incident field. Results for different targets with multistatic source–receiver configurations and with focused acoustic incident fields are presented.
Range-dependent reverberation modeling with the parabolic equation
Authors: Ratilal Purnima , Lee Sunwoong , Makris Nicholas C.
Published: October 2013

Propagation and scattering are generally convolved in a waveguide. For scatterers small compared to the wavelength, however, the waveguide Green functions to and from the scatterer can be separated from the free space scattering amplitude [Ratilal et al., J. Acoust. Soc. Am. 112, 1797–1816 (2002)]. In this case, waveguide scattering can be modeled using efficient and accurate range-dependent methods such as the parabolic equation (PE) for the waveguide Green function. This approach is implemented for scattering from small particles in the water column and seabed at arbitrary bistatic orientations. Scenarios investigated involving targets of large impedance contrast include scattering from bubbles and fish schools. When the Rayleigh–Born single scatter approximation is valid, PE-based range-dependent scattering can also be used to scatter from elemental water-column and seabed inhomogeneities. This approach is used to model bistatic reverberation from the water column and seabed including returns arising from both diffuse and discrete scattering processes. The former is associated with smoothly decaying reverberation, the latter with clutter. Also, the possibility that internal waves may lead to discrete seafloor scattering returns by focusing energy on the ocean bottom is also investigated with this model.
Uniform approximation method for backscattering of sound from a target in a caustic field
Authors: Dzikowicz Ben , Marston Philip L.
Published: October 2013

In certain cases, underwater backscattering of sound by targets in a caustic field associated with reflection from curved surfaces takes the form of a diffraction integral over the product of a wavefront amplitude and a phase factor. The phase factor can be expressed using the relative return times of a transient pulse (B. Dzikowicz, Ph.D. dissertation, Washington State University, Pullman, WA, 2003). In a homogeneous, isotropic medium, the variation in ray return angles can be related to geometrically predicted ray amplitudes at the receiver. These geometrically predicted amplitudes as a function of target position can be recovered from the diffraction integral by using the results of a uniform approximation [C. Chester, B. Friedman, and F. Ursell, Proc. Cambridge Philos. Soc. 53, 599–611 (1957)]. The result is that for targets near an Airy caustic, the coefficient of the Airy function amplitude factor depends on the derivatives of ray return angles. The improvement using this technique for two merging rays (a target at an Airy caustic) versus a simpler model (where the aforementioned coefficient is constant) will be discussed and compared to experiment for the single-bounce echo. [Work supported by ONR.]
Musical acoustics demonstrations
Authors: Hoekje P. L.
Published: October 2013

The ASA Musical Acoustics Demonstrations website (trial version at http://www.bw.edu/∼phoekje) includes sound files, video clips, program code listings, and other material for demonstrations related to musical acoustics. Many of the sound demonstrations may be experienced either as expositions, in which the phenomena are explained before they are presented, or as experiments, in which the explanation comes after listeners have had the opportunity to draw their own conclusions. Suggestions are provided for apparatus construction and classroom experiments, as well as for building simple musical instruments. Software is recommended if it is available free and compatible with multiple personal computer operating systems. For example, Audacity (http://audacity.sourceforce.net) is a sound file editor and analyzer that can be used to visually represent sounds and manipulate them. Source files are included for the synthesized sound examples, which were created in Csound (http://csounds.com), so that interested users may create their own variations. Source code is also included for visual demonstrations created in Visual Python and Python (http://www.python.org), an efficient, high level programming language. Suggestions, criticisms, and contributions are always welcome! [Work supported by ASA and Baldwin-Wallace College.]
‘‘Lurching waves’’ in DPGraph
Authors: Ayers R. Dean , Inan Nader
Published: October 2013

Introductory treatments of waves usually emphasize undamped traveling waves and ideal standing waves with perfect nodes. Those are just special cases from a larger class of waves in which the crests perform a characteristic ‘‘lurching’’ or ‘‘galloping’’ motion. The variation of a terminal reflection coefficient and the constant for damping in propagation generates a continuum of more realistic behaviors that connect the special, simple cases. Attempts to develop this larger class verbally and mathematically might seem abstract and complicated, but the use of kinetic computer graphics in an interactive mode makes their introduction straightforward. Preliminary observations and explorations with these images can then lead naturally to a mathematical treatment at a level appropriate for the audience. Software from DPGraph has been particularly convenient for the development of the figures. The fact that programming must be done using analytic expressions and no iterations is a valuable constraint; it forces the user to stay close to fundamentals in the physics and mathematics. Exploratory studies then encourage the programmer to ask analytic questions that might not have been considered otherwise. Several representative figures will be presented. [Work supported by the Paul S. Veneklasen Research Foundation and the CSULB Scholarly and Creative Activities Committee.]
Using acoustics to lure high school students into a career in science
Authors: Piacsek Andrew
Published: October 2013

As part of a National Science Foundation STEP grant to stimulate recruitment and improve retention of students in science, mathematics, and technology, several science faculty at Central Washington University developed a 2-week summer program for high school students entering their senior year. From June 23 to July 2, 2003, 13 high school juniors from the primarily agricultural region of central Washington lived on the CWU campus and spent their days working on college-level science projects with CWU faculty. Each week, the students worked in groups of three or four with a faculty mentor from one of five disciplines: chemistry, biology, geology, physics, and computer science. The week-long physics project consisted of a series of simple experiments designed to build an understanding of standing waves and resonance. By the end of the week, students were testing hypotheses relating the resonance frequency of a wineglass to its thickness, height, and opening diameter. They also measured Q for several glasses and chose the one with the highest Q to break with sound from a loudspeaker. Although the students were in the lab for an average of 4.5 h per day, they showed unflagging enthusiasm.
Controlling loudspeakers in rooms
Authors: Pedersen Jan Abildgaard , Praestgaard Poul
Published: October 2013

How to control the perceived timbre of a loudspeaker in different listening positions, using different loudspeaker positions in different listening rooms is a central problem, when designing and using loudspeakers is discussed. Loudspeaker directivity has been found to be one of the critical parameters in the solution to this problem. This paper presents three hypotheses for the optimal loudspeaker directivity and a novel realization of that directivity, i.e., the Acoustic Lense (ALT). The dominant problem at low frequencies has been found to relate to the fact, that the acoustic power output of loudspeakers is highly dependent on the loudspeaker position and on the acoustic properties of the listening room. This paper also presents a novel system for adapting a loudspeaker to its position and to the acoustic properties of the listening room, i.e., Adaptive Bass Control (ABC).
Real-time virtual room acoustic simulation
Authors: Carneal James P. , Johnson Jan , Johnson Troge , Johnson Marty
Published: October 2013

A realistic virtual room acoustic simulation has been implemented on a PC-based computer in near real-time. Room acoustics are calculated by the image source method using realistic absorption coefficients for a variety of realistic surfaces and programmed in MATLAB. The resulting impulse response filters are then applied in near real-time using fast convolution DSP techniques using data being read from a CD-ROM. The system was implemented in a virtual acoustic room facility. Optimizations have been performed to retain the realistic virtual room effect while minimizing computations through limited psycho-acoustic testing. In general, realistic anechoic to reverberant virtual rooms have been re-created with six 8192 coefficient filters. To provide realistic simulations, special care must be taken to accurately reproduce the low frequency acoustics. Since the virtual room acoustic facility was not totally anechoic (as are most anechoic chambers), inverse filters were applied to compensate for over-amplified acoustics at frequencies below 350 Hz.
Ups and downs of a gas horizon under environmental control
Authors: Wever Thomas F.
Published: October 2013

Repeated measurements with a sub-bottom profiler along reference tracks in Eckernförde Bay (Western Baltic) led to the recognition that acoustic turbidity (the ‘‘gas horizon’’) within the muddy sediments changed its depth. Soon a dependence on the annual temperature cycle with a 3–4 month delay became obvious. In addition, short-term variations correlated with atmospheric pressure changes. For a further investigation, a tower equipped with an echosounder, pressure, and temperature probes at different sediment depths was deployed for four years in the center of the bay. Data were recorded every hour. The data show the migration of the annual temperature peak and low through the sediment and its long-term influence on acoustic turbidity depth. Short-term (‘‘high-frequency’’) variations can be correlated with changes in total effective pressure. Repeated investigations of the total methane content in sediment cores during different times of the year and the analysis of the cores with the use of computer tomography under the guidance of Aubrey L. Anderson proved a constant total methane content. This led to the explanation that the environmental factors pressure and temperature cause variations of gas solubility that move up and down and thus control the existence or absence of free gas bubbles within the sediment.
Amplitude and frequency experimental field measurements of a rotating-imbalance seismic source associated with changes in lithology surrounding a borehole
Authors: Novascone Stephen R. , Anderson Michael J. , Weinberg David M. , Cole Jack H.
Published: October 2013

Field measurements of the vibration amplitude of a rotating-imbalance seismic source in a liquid-filled borehole are described. The borehole was a cased oil well that had been characterized by gamma-ray cement bond and compensated neutron litho-density/gamma-ray logs. The well logs indicated an abrupt transition from shale to limestone at a depth of 2638 ft. The vibration amplitude and frequency of a rotating-imbalance seismic source was measured versus applied voltage as the source was raised from 2654 to 2618 ft through the shale–limestone transition. It was observed that the vibration amplitude changed by approximately 10% in magnitude and the frequency changed approximately 15% as the source passed the shale–limestone transition. The measurements were compared to predictions provided by a two-dimensional analytical model of a rotating-imbalance source located in a liquid-filled bore hole. It was observed that the sensitivity of the experimentally measured vibration amplitude of the seismic source to the properties of the surrounding geologic media was an order of magnitude greater than that predicted by the two-dimensional analytical model.
Inversion for acoustic impedance using artificial neural network algorithm
Authors: Too Gee-Pinn , Hwang Suzi
Published: October 2013

A new approach for measuring acoustic impedance is developed by using Artificial Neural Network (ANN) algorithm. Instead of using impedance tube, a rectangular room or a box is simulated with known boundary conditions at some boundaries and a unknown acoustic impedance at one side of the wall. The training data basis for the ANN algorithm is evaluated by Similar Source Method which was developed earlier by Too (1999) for the estimation of interior and exterior sound field. The training data basis is constructed by evaluating of acoustic pressure at a field point with various acoustic impedance conditions at one side of the wall. The simulation result indicates that the prediction of acoustic impedance is very accurate with error percentage under 1%. Also, one point field measurement in the present approach provides a straightforward and easy evaluation than that in the two points measurement of the impedance tube approach.
Linear and nonlinear behavior of human and artificial lip reeds
Authors: Campbell Murray , Richards Orlando
Published: October 2013

In a musical instrument of the lip reed aerophone class, the flow of air from the player’s lungs into the resonating air column is modulated by the periodic opening and closing of the pressure-controlled valve formed by the player’s lips. The nature of the operation of this valve has been the subject of considerable study in recent years. Since the pressure–flow relationship is strongly nonlinear, the behavior of the coupled system of lips and air column can only be modeled using the methods of nonlinear dynamics. Extensive studies of artificial lip reeds, in which the lips are simulated by water-filled latex tubes, have shown them to be capable of reproducing musically important features of human playing, including the lipping of notes both below and above an acoustic resonance of the air column. Measurements of the linear response of artificial reeds have guided the development of more realistic models of the lip reed, while studies of both real and artificial lips using a high-speed digital camera have shed fresh light on the nature of the lip motion at the large amplitudes typical of loud playing. [Work supported by EPSRC.]
Propagation of nonlinear acoustic waves and shocks in variable cross-section resonators
Authors: Lipkens Bart
Published: October 2013

Relative peak acoustic pressures in wind instruments such as oboes, trumpets, and trombones can reach levels of 10%. At these elevated levels nonlinear acoustic effects have to be taken into account to accurately represent the acoustic wave propagation in these wind instruments. A short survey is presented of some of the past work in nonlinear resonant oscillations in tubes. Included in this discussion is the effect of shaping the resonator on nonlinear wave propagation. A one-dimensional model for the analysis of nonlinear acoustic waves in a variable cross-section resonator is introduced [Ilinski et al., J. Acoust. Soc. Am. 104, 2664–2674 (1998)]. The resonator is assumed to be of an arbitrary axisymmetric shape. The model equations are derived from the fundamental gas dynamic equations for an ideal gas. The effects of bulk viscous absorption and absorption in the viscous boundary layer are included. Nonlinear spectral equations are developed which are integrated numerically to obtain the solution. The model has been modified to include a radiation impedance and the excitation of a harmonic spectrum. The effect of resonator shape, radiation condition, and harmonic excitation on nonlinear wave propagation is discussed.
Feathering collisions in beating reed simulation
Authors: Smyth Tamara , Abel Jonathan S. , Smith Julius O.
Published: October 2013

Pressure controlled valves are the primary sound production mechanisms for woodwind and brass musical instruments, as well as for many bioacoustic vocal systems such as the larynx and syrinx (the vocal organ in birds). During sound production, air flow sets a reed or membrane into motion creating a variable height in the valve channel and, potentially, periodically closing the channel completely. Depending on how this event is handled, an abrupt termination of air flow between open and closed states can cause undesirable discontinuities and inaccuracies in a discrete-time simulation—particularly at relatively low audio sampling rates. A solution was developed by re-examining the behavior of the differential equation governing volume flow through a pressure-controlled valve, paying particular attention to this rather troublesome transition. A closed-form solution for the time evolution of volume flow is given and used to derive an update for volume flow. The result is a smoother, more accurate, and nearly alias-free transition from open to closed. ‘‘Feathered collisions’’ of this nature can refine the sound quality produced by the numerical simulation of beating reeds, such as in clarinets, at typical audio sampling rates.
Error metrics for predicting discrimination of original and spectrally altered musical instrument sounds
Authors: Beauchamp James W. , Horner Andrew
Published: October 2013

The correspondence of various error metrics to human discrimination data was investigated. Time-varying harmonic amplitude data were obtained from spectral analysis of eight musical instrument sounds (bassoon, clarinet, flute, horn, oboe, saxophone, trumpet, and violin). The data were altered using fixed random multipliers on the harmonic amplitudes, and the sounds were additively resynthesized with estimated average spectral errors ranging from 1% to 50%. Listeners attempted to discriminate the randomly altered sounds from reference sounds resynthesized from the original data. Then, various error metrics were used to calculate the spectral differences between the original and altered sounds, and the R2 correspondence between the error metrics and the discrimination data was measured. A relative-amplitude spectral error metric gave the best correspondence to average subject discrimination data, capturing over 90% of the variation relative to a Fourth-order regression curve, although other formulas gave similar results. Error metrics which used a small number of representative analysis frames gave results which compared favorably to using all frames of the analysis.
The rams horn in western history
Authors: Lubman David
Published: October 2013

The shofar or rams horn—one of the most ancient of surviving aerophones—may have originated with early Neolithic herders. The shofar is mentioned frequently and importantly in the Hebrew bible and in later biblical and post-biblical literature. Despite its long history, contemporary ritual uses, and profound symbolic significance to western religion, no documentation of shofar acoustical properties was found. Since ancient times, shepherds of many cultures have fashioned sound instruments from the horns of herd animals for practical and musical uses. Shepherd horns of other cultures exhibit an evolution of form and technology (e.g., the inclusion of finger holes). The shofar is unique in having retained its primitive form. It is suggested that after centuries of practical use, the shofar became emblematic of the shepherd culture. Ritual use then developed, which froze its form. A modern ritual rams horn played by an experienced blower was examined. This rather short horn was determined to have a source strength of 92 dB (A) at 1 m, a fundamental frequency near 420 Hz, and maximum power output between 1.2 and 1.8 kHz. Sample sounds and detection range estimates are provided.
Acoustical criteria for hospital patient rooms: Resolving competing requirements
Authors: Brooks Bennett M.
Published: October 2013

The acoustical criteria for patient rooms in hospitals, nursing homes, and rehabilitation facilities may be based on several needs. One important requirement is that noise levels in the room be conducive to restful sleep. Also, caregivers must have easy auditory and visual access to the patients, and be able to hear vital sign monitor alarms. This often means that patient rooms are located near central nurse stations and that patient room doors are left open. Further, the recently published federal privacy standards developed by the U.S. Department of Health and Human Services (HSS) under the Health Insurance Portability and Accountability Act (HIPAA) require that ‘‘appropriate physical safeguards’’ be put in place to protect the confidentiality of patient health information. The simultaneous and competing requirements for speech privacy, caregiver access, and good sleeping conditions present a serious acoustical challenge to health care facility designers. Specific facility design issues and potential solution strategies are presented.
Noise levels, spectra, and operational function of an occupied newborn intensive care unit built to meet recommended permissible noise criteria
Authors: Philbin M. Kathleen , Evans Jack B.
Published: October 2013

A group of clinical experts developed recommended permissible noise criteria for newly constructed or renovated hospital nurseries [Philbin et al., J. Perinatol. 19, 559–563 (2000); R. White, ibid. 23, S1–22 (2003)]. These criteria are based principally on research regarding wake-up thresholds for term newborns and speech interference levels for adults. These criteria are: The overall continuous A-weighted, slow response, sound level at any bed or patient care area shall not exceed: (1) an hourly Leq of 50 dB, (2) an hourly L10 of 55 dB, and (3) a 1-s Lmax of 70 dB. A new hospital building was designed to meet these criteria by using specific acoustical criteria for the structure and space arrangement [J. B. Evans and M. K. Philbin, J. Perinatol. 20, S105–S112 (2000)]. Acoustical criteria for sound isolation, background NC, structural vibration, and reverberation will be presented along with space arrangements that ensure staff efficiency, clinical safety, and family privacy. Post-occupancy measurements of sound levels and spectra along with photographs of a nursery in operation will be presented to illustrate how an ICU can have a quiet, highly functioning intensive care environment while meeting the operational goals and acoustical criteria.
Structure-borne sound from magnetic resonance imaging systems
Authors: Ungar Eric E. , Zapfe Jeffrey A.
Published: October 2013

Magnetic resonance imaging (MRI) systems are known to produce a considerable amount of audible noise. The recent tendency to install such systems on above-grade floors has led to increasing concerns about structure-borne noise transmission from the MRI to adjacent occupied areas. This paper presents the results of a study in which structure-borne noise forces produced by two operational MRI systems were determined via measurement of the floor vibrations induced by the systems and of the impedance of their supporting floors. Forces with known spectra were applied to the floors of planned MRI suites in a hospital extension and the corresponding noise in adjacent areas was measured. Similarly, airborne noise was introduced in the planned suites and the related noise in adjacent areas was measured. The results then were scaled to correspond to the measured MRI forces and airborne noise. It was found that in areas below the planned MRI installations structure-borne noise would predominate, unless it is mitigated. Structure-borne noise isolation of MRI systems, whose environments must meet stringent vibration criteria, is discussed briefly.
The performance of a high-frequency thermoacoustic-Stirling engine
Authors: Bastyr Kevin J. , Keolian Robert M.
Published: October 2013

A thermoacoustic-Stirling engine that operates at 400 Hz with a working fluid of 1-MPa helium is constructed. For proper acoustic phasing in this engine’s regenerator, an acoustic power feedback path exists in the form of an annulus surrounding the regenerator. This feedback path is obtained by suspending an insulated, stainless steel sleeve containing a wire mesh regenerator, which is flanked by two heat exchangers, a short distance from one end of the larger diameter resonator. The ambient heat exchanger is a shell and tube exchanger, while the hot heater consists of nichrome ribbon wound on an aluminum silicate frame. Gedeon streaming is prevented by a diaphragm covering the end of the stainless steel sleeve adjacent to the ambient heat exchanger. A variable acoustic load provides a convenient means of testing this engine at various hot heater temperatures, while operating at different acoustic pressure amplitudes effects the acoustic power generated by the engine. [Work supported by ONR.]
Stimulus-driven and knowledge-driven processes in attention to warbles
Authors: Dowling W. Jay , Tillmann Barbara
Published: October 2013

Listeners identified warbles differing in amplitude-modulation rate (3–10 Hz). And measured RT while listeners maintained above 90% correct responses. After a practice session listeners identified target warbles following stimulus-driven or knowledge-driven cues. The stimulus-driven cue was a 250-ms ‘‘beep’’ at the target pitch (valid) or another pitch (invalid); the knowledge-driven cue was a midrange ‘‘melody’’ pointing to the target pitch (always valid). A 500-ms target warble followed the cue after delays of 0–500 ms (250–750 ms SOA). The listener pressed a key to indicate ‘‘slow’’ or ‘‘fast.’’ RTs were shortest at the briefest delay. In contrast to results from a memory task, RTs here were much shorter, and we found no evidence for IOR or attentional blink. Listeners began generating responses while the target was still sounding. Invalid ‘‘beeps’’ slowed responses at the briefest (but not the longer) delays; adding a valid ‘‘beep’’ to the valid ‘‘melody’’ did not speed responses.
Effect of a non-target sound event on motion perception of a target sound event
Authors: Nishida Tsuruyo , Kakehi Kazuhiko
Published: October 2013

Most psychoacoustics studies on sound localization and motion perception have been conducted for only one sound event. In this report, one- or two-sound events were presented and the direction and motion perception were investigated using two-sound phenomena to produce motion perception; the first was apparent motion and the second was a synthesized sound image. There were no significant differences in the correct response percentage for both two-sound phenomena. The correct response percentage for the direction of motion was significantly worse for two-sound events than that for one-sound event, even if the two-sound events are separately perceived in terms of frequency, space domain, and temporal order. The analysis of wrong responses showed that the perception depends on IEOIs and the combination of target and non-target moving conditions (e.g., moving or still). Furthermore, it was clarified with signal detection theory that the motion perception of target was strongly affected by the non-target conditions. It means that the process of perceiving the direction and motion of the target might be different than that of perceiving the sound feature.
Subjective assessment for the number of channel signals to realize sound field based on wavefield synthesis
Authors: Kimura Toshiyuki , Kakehi Kazuhiko , Takeda Kazuya , Itakura Fumitada
Published: October 2013

It is very important to study the affect of the number of channel signals in the sound field reproduction technique based on wavefield synthesis. Though there are many studies of objective affect such as wavefront accuracy, there are not as many studies of the subjective affect such as sound field perception. Therefore, the subjective assessment was designed to evaluate the effect of the number of channel signals, which were synthesized by convolving a sound source to room transfer functions of free field, on the directional perception. In the low-reverberation room, a circle loudspeaker array with a radius of 2 m was set on the horizontal plane. The subjects evaluated the directional perception of the sound image reproduced at distances of 3 and 4 m by playing simultaneous channel signals from the loudspeakers set at intervals of 10, 15, 20, 30, and 45 degrees, respectively. As a result, it was subjectively confirmed that 24 channel signals were enough to reproduce the directional perception of 5 degrees accuracy if the control area was the circle of radius 2 m.
A 3-D hp-adaptive finite-element code for modeling acoustic scattering from elastic structures
Authors: Burnett David S. , Zampolli Mario
Published: October 2013

The Centre has developed a 3-D hp-adaptive finite-element structural acoustics code, FESTA, for modeling acoustic scattering from underwater elastic structures. The project is using a unique commercial software system for developing customized application codes. To develop a code, the researcher derives the Galerkin residual equations and then links a self-written code with a vendor-written application-independent library of routines, which creates an application code with a commercial-quality GUI. For FESTA the entire fluid-structure domain is treated as a single continuum, which is modeled using only one type of finite element: a fluid-solid element. The wave equations for both media are derived from the same underlying equations of continuum mechanics, and then combined into a single wave equation, from which the fluid–solid finite element is derived. The code employs 3-D continuum mechanics throughout the computational domain. Thin structural components, such as plates and shells, are modeled with 3-D physics rather than plate or shell theories. The code is therefore fully 3-D, i.e., in both physics and geometry. This paper will describe the theoretical development and present several scattering and propagation models analyzed by FESTA.
Computing fluid-coupled resonance frequencies, mode-shapes, and damping loss factors using the singular value decomposition
Authors: Fahnline John B.
Published: October 2013

In many acoustic design problems, it would be useful to be able to compute fluid-coupled resonance frequencies, mode shapes, and their associated damping levels. Unfortunately, conventional eigenvalue solution procedures are either computationally-inefficient, unreliable, or have limited applicability. Sophisticated methods for identifying modal parameters using the singular value decomposition have recently emerged in the area of experimental modal analysis, where the available data typically consists of velocity to force transfer function data as a function of frequency for several drive point locations. Here, these techniques are shown to be even more effective for coupled finite element/boundary element solutions because full matrices of transfer function data can be computed as a function of frequency. This allows the modes to be completely separated from each other, such that the modal parameters can be identified using simple methods designed for single degree of freedom systems. Several benchmark example problems are solved numerically including a baffled circular plate, an unbaffled rectangular plate, and a spring-mounted piston coupled to fluid within a rigid-walled pipe.
A comparison of speech recognition training programs for cochlear implant users: A simulation study
Authors: McCabe Marie E. , Chiu C.-Y. Peter
Published: October 2013

The present simulaton study compared two training programs with very different design features to explore how each might improve the ability of listeners with normal hearing to recognize speech generated by a cochlear implant simulator. The first program, which focused training on specific areas of difficulty for individual patients across multiple levels of linguistic content (e.g., vowels, consonants, words, and sentences), was modeled after a standard program prescribed by one of the US manufacturers of cochlear implants. The second program consisted of exposure to multiple sentences with feedback regardless of subjects’ performance level, and had been used in previous studies from this laboratory. All speech materials were reduced spectrally to simulate an 8-channel CIS cochlear implant processor with a ‘‘6mm frequency upshift’’ [Fu and Shannon, J. Acoust. Soc. Am. 105, 1889 (1999)]. Test sessions were administered to all subjects to assess recognition of sentences, consonants (/aCa/), and vowels (in /hVd/ and /bVt/ contexts) pre- and post-training. In a subset of subjects, a crossover design, in which subjects were trained first with one program and then with the other, was employed. Results will be discussed both in terms of theory and practice of therapeutic programs for cochlear implant users.
Processing of speech and non-speech stimuli in children with specific language impairment
Authors: Basu Madhavi L. , Surprenant Aimee M.
Published: October 2013

Specific Language Impairment (SLI) is a developmental language disorder in which children demonstrate varying degrees of difficulties in acquiring a spoken language. One possible underlying cause is that children with SLI have deficits in processing sounds that are of short duration or when they are presented rapidly. Studies so far have compared their performance on speech and nonspeech sounds of unequal complexity. Hence, it is still unclear whether the deficit is specific to the perception of speech sounds or whether it more generally affects the auditory function. The current study aims to answer this question by comparing the performance of children with SLI on speech and nonspeech sounds synthesized from sine-wave stimuli. The children will be tested using the classic categorical perception paradigm that includes both the identification and discrimination of stimuli along a continuum. If there is a deficit in the performance on both speech and nonspeech tasks, it will show that these children have a deficit in processing complex sounds. Poor performance on only the speech sounds will indicate that the deficit is more related to language. The findings will offer insights into the exact nature of the speech perception deficits in children with SLI. [Work supported by ASHF.]
A novel probabilistic framework for event-based speech recognition
Authors: Juneja Amit , Espy-Wilson Carol
Published: October 2013

One of the reasons for unsatisfactory performance of the state-of-the-art automatic speech recognition (ASR) systems is the inferior acoustic modeling of low-level acoustic-phonetic information in the speech signal. An acoustic-phonetic approach to ASR, on the other hand, explicitly targets linguistic information in the speech signal, but such a system for continuous speech recognition (CSR) is not known to exist. A probabilistic and statistical framework for CSR based on the idea of the representation of speech sounds by bundles of binary valued articulatory phonetic features is proposed. Multiple probabilistic sequences of linguistically motivated landmarks are obtained using binary classifiers of manner phonetic features—syllabic, sonorant and continuant—and the knowledge-based acoustic parameters (APs) that are acoustic correlates of those features. The landmarks are then used for the extraction of knowledge-based APs for source and place phonetic features and their binary classification. Probabilistic landmark sequences are constrained using manner class language models for isolated or connected word recognition. The proposed method could overcome the disadvantages encountered by the early acoustic-phonetic knowledge-based systems that led the ASR community to switch to systems highly dependent on statistical pattern analysis methods and probabilistic language or grammar models.
Structural equation modeling for estimating the identification accuracy and detection time latency of English monosyllabic words
Authors: Takayanagi Sumiko , Bernstein Lynne E. , Auer Edward T.
Published: October 2013

Structural equation modeling (SEM) was used to examine the statistical structure among sets of experiential (word age of acquisition and subjective familiarity) and lexical similarity (lexical equivalence class size and neighborhood density) variables for word identification and reaction time latency tasks. Stimuli were 240 vocoded monosyllabic English words with reduced intelligibility and altered similarity relationships. Participants detected a target word following a prime and on every trial reported the prime. The identification accuracy was estimated by words and phonemes correct, and detection latency was estimated by trimmed and harmonic mean RTs. A parsimonious SEM was chosen in terms of the chi-square and model fit indices that determine whether the models adequately described the particular associations of variables/interfactor relationships. The variable/factor error variances were constrained to be uncorrelated with each other in order to evaluate effects independently. A bootstrapping technique indicated that the regression weights of the top-down and bottom-up factors were small, but they were significant in the model. The variance accounted for (VAF) by the model was 7.1% for identification accuracy, and 5.2% for RT latency. The model also indicated that RT latency was highly influenced by prime identification accuracy (15% VAF). [Work supported by NIH/NIDCD00695.]
Two-C but not two-V: Segment similarity in learning an artificial lexicon
Authors: Creel Sarah C. , Aslin Richard N. , Tanenhaus Michael K.
Published: October 2013

The role of segment similarity (C1—C2—or —V1—V2) in a word learning task was assessed using an artificial lexicon in a referential context. Learning consisted of 480 trials in which S’s heard one of 40 CVCV nonsense strings, accompanied by an unfamiliar picture. In testing, participants heard the direction ‘‘Click on the [nonsense word],’’ and chose one of four pictures that matched the test item. On some trials, target lexical items (pibo) appeared with foils that contained matched consonants (pabu) or matched vowels (diko). There were higher rates of confusion errors to the matched-consonant items than to non-matched items, but no significant elevation in errors to matched-vowel items. A second experiment examined the role of differences in informativeness between C’s and V’s by inverting the numbers of C and V types (first experiment: 10 C, 5 V; second experiment: 5 C, 10 V). This made the consonants less predictive of word identity (more words contained the same consonants), and made the vowels more predictive of word identity. The matched-consonant effect remained undiminished while no corresponding matched-vowel effect emerged, ruling out a segment-informativeness explanation. Other accounts based on the syllable positions and confusability patterns of consonants are being explored.
AXS and SOM: A new statistical approach for treating within-subject, time-varying, multivariate data collected using the AXS Test Battery
Authors: Lauter Judith L. , Ninness Chris
Published: October 2013

The Auditory Cross-Section (AXS) Test Battery [J. L. Lauter, Behav. Res. Methods Instrum. Comput. 32, 180–190 (2000)], described in presentations to ASA in 2002 and 2003, is designed to document dynamic relations linking the cortex, brainstem, and body periphery (whether physics, physiology, or behavior) on an individually-specific basis. Data collections using the battery typically employ a within-subject, time-varying, multivariate design, yet conventional group statistics do not provide satisfactory means of treating such data. We have recently developed an approach based on Kohonens (2001) Self-Organizing Maps (SOM) algorithm, which categorizes time-varying profiles across variables, either within- or between-subjects. The treatment entails three steps: (1) z-score transformation of all raw data; (2) employing the SOM to sort the time-varying profiles into groups; and (3) deriving an estimate of the bounds for the Bayes error rate. Our three-step procedure will be briefly described and illustrated with data from a recent study combining otoacoustic emissions, auditory brainstem responses, and cortical qEEG.
Perceptual rate normalization in naturally produced bilabial stops
Authors: Nagao Kyoko , de Jong Kenneth
Published: October 2013

The perception of voicing categories is affected by the speaking rate, so that listeners’ category boundaries on a VOT continuum shift to a lower value when the syllable duration decreases (Miller and Volaitis, 1989; Volaitis and Miller, 1992). Previous rate normalization effects have been found using computer-generated stimuli. This study examines the effect of speech rate on voicing categorization in naturally produced speech. Four native speakers of American English repeated syllables (/bi/ and /pi/) at increasing rates in time with a metronome. Three-syllable stimuli were spliced from the repetitive speech. These stimuli contained natural decreases in VOT with faster speech rates. Besides, this rate effect on VOT was larger for /p/ than /b/, so that VOT values for /b/ and /p/ overlapped at the fastest rates. Eighteen native listeners of American English were presented with 168 stimuli and asked to identify the consonant. Perceptual category boundaries occur at VOT values 15 ms shorter than the values reported for synthesized stimuli. This difference may be due to the extraordinarily wide range of VOT values in previous studies. The values found in the current study closely match the actual division point for /b/ and /p/. The underlying mechanism of perceptual normalization will be discussed.
Novel error sensing microphone arrays for active control of turbofan rotor/stator tones
Authors: Walker Bruce E. , Hersh Alan S. , Rice Edward J. , Sutliff Daniel L.
Published: October 2013

Active control of turbofan rotor/stator interaction tones is complicated by the simultaneous presence of multiple duct propagation modes. In-duct error sensing microphone arrays that can adequately resolve these modes typically require duct lengths that are incompatible with modern compact engine design. Two alternative approaches have been investigated. For inlet noise, an external linear array of microphones was positioned in the near/far radiation field transition region and weighted to provide error signals resolved either by duct mode or by radiation angle. For the exhaust, radially spaced microphones have been placed on duct bifurcation panels to provide supplemental radial-mode resolution. The concepts were tested in combination with an adaptive segmented liner in a static duct and as part of an active stator-vane system in the ANCF research facility at NASA/Glenn Research Center. [Work sponsored by NASA/Langley Research Center.]