bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Effects on the Mechanical Behavior of Buckled Thin Film
Authors: Wang Yong , Feng Xue , Lu Bingwei , Wang Gangfeng
Published: September 2012

The buckling of thin films with natural nonlinearity can provide a useful tool in many applications. In the present paper, the mechanical properties of controllable buckling of thin films are investigated by accounting for both geometric nonlinearity and surface effects at nanoscale. The effects of surface elasticity and residual surface tension on both static and dynamic behaviors of buckled thin films are discussed based on the surface-layer-based model. The dynamic design strategy for buckled thin films as interconnects in flexible electronics is proposed to avoid resonance in a given noise environment based on the above analysis. Further discussion shows that the thermal and piezoelectric effects on mechanical behavior of buckled thin film are equivalent to that of residual surface tension.
Characterization of distensibility, plaque burden, and composition of the atherosclerotic carotid artery using magnetic resonance imaging
Authors: Cantón Gádor , Hippe Daniel S. , Sun Jie , Underhill Hunter R. , Kerwin William S. , Tang Dalin , Yuan Chun
Published: September 2012

Purpose:

Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis with applications including estimation of mechanical properties of the wall. We sought to assess the feasibility of using magnetic resonance imaging (MRI) to include wall distensibility in the characterization of atherosclerotic carotid arteries and to analyze the relationship between distensibility and morphological and compositional plaque features.

Methods:

Five healthy volunteers were imaged with a multiple‐slice CINE MR sequence twice, within 24 h, to determine the interscan reproducibility of distensibility measurements. Twenty‐one subjects with >15% carotid stenosis and the five healthy volunteers were imaged using a multicontrast carotid MRI protocol to characterize arterial wall morphology and composition. Normalized wall index (wall area/total vessel area), maximum wall thickness and, if present, percentages of wall area occupied by calcification and lipid‐rich necrotic core were determined. A multiple‐slice CINE MR sequence was added to the multicontrast protocol to measure the distensibility coefficient (DC) at several locations spanning the bifurcation. The intraclass correlation coefficient (ICC) and the coefficient of variation were used to assess the reproducibility of DC measurements made on the healthy subjects. The DC was compared between arterial segments and between the healthy and diseased groups. Furthermore, within the diseased group, DC was correlated to plaque morphology and composition at each location as well as that averaged over the plaque.

Results:

Distensibility measurements were highly reproducible: ICC (95% confidence interval) was 0.998 (0.96–1.0) for the common carotid segment and 0.990 (0.92–1.0) for the internal carotid segment. In healthy volunteers, we found significantly higher distensibility in the common segment of the carotid artery compared to the internal carotid segment (mean ± SD = 4.56 ± 1.02 versus 3.56 ± 1.32 × 10−5/Pa;p< 0.05). However, no segmental differences were seen in the diseased group (3.25 ± 1.84 versus 3.26 ± 1.60 × 10−5/Pa;p= 0.607). Location‐to‐location changes in DC were not found to correlate to changes in the local plaque morphology or composition nor were average DC found to be associated with aggregate plaque features.

Conclusions:

These results demonstrate the feasibility of MRI to measure distensibility in the carotid artery and to presumably detect changes in distensibility due to age and/or disease. The results suggest that the effect of atherosclerosis on local distensibility may not strongly depend upon the specific underlying plaque features in mild to moderate stenotic carotid lesions though more diffuse or nonlocal changes in arterial distensibility could not be ruled out.
Low frequency acoustical scattering properties of large schools of swim bladder fish
Authors: Raveau María P. , Feuillade Christopher
Published: September 2012

The collective back scattering behavior of fish schools has previously been described by a school scattering model [J. Acoust. Soc. Am., 99(1), 196-208 (1996)], which incorporates both multiple scattering effects between neighboring fish, and coherent interactions of their individual scattered fields. In the present work, the school scattering model has been extended, and used to investigate the back- and forward-scattering properties of the acoustic field, and transmission through, large schools of swim bladder fish, at frequencies close to the swim bladder resonance frequency. Results show that their frequency and spatially-varying scattering behavior depends strongly upon the number of fish in the school ensemble, the species specific swim bladder size, the average spacing between fish, and the size and shape of the school. Results will also be presented of a comparison between the school model and fish absorption data obtained during the experiment Modal Lion, performed in the Gulf of Lion in September 1995, and reported by Diachok [J. Acoust. Soc. Am., 105(4), 2107-2128 (1999)]. [Work supported by ONR.]
Choir hearing responses: Rehearsal versus performance configurations
Authors: Sweitzer Glenn E.
Published: September 2012

Choir member responses to hearing (sung parts) in a rehearsal room are compared with those for its associated performance stage. Anonymous scaled responses from each choir member are gathered simultaneously using a personal response system. The protocol is repeated in a rehearsal room for the choir voices configured by 1) part versus mixed; and 2) on risers versus flat floor. On the performance stage, the protocol is repeated for same. Prior to each set of responses, the choir sings a prayer familiar to the choir members. The responses vary widely between rehearsal and performance venues, and by configuration in each. These findings suggest that choir member response may be largely ignored in the design and operation of choir rehearsal and performance facilities. Potentials for improving choir member hearing in existing rehearsal and performance venues is discussed.
On the use of micro-perforates for machinery and vehicle noise control
Authors: Åbom Mats , Allam Sabry
Published: September 2012

A micro-perforated plate (MPP) is a perforated plate with holes typically in the sub-millimeter range and perforation ratio around 1%. The values are typical for applications in air at standard temperature and pressure (STP). The underlying acoustic principle is simple: To create a surface with a built in damping that effectively dissipates sound waves. To achieve this, the specific acoustic impedance of a MPP is normally tuned to be of the order of the characteristic wave impedance in the medium (400 Pa*s/m in air at STP). The traditional application for MPP's has been building acoustics, normally in the form of a so called panel absorber to create an absorption peak at a selected frequency. However, MPP's made of metal are also well suited for machinery and vehicle noise control. For instance MPP's have the potential to be used instead of porous materials in dissipative mufflers, which not only can save weight but also offer a non-fibrous alternative. Furthermore, since MPP's have a large steady flow resistance they can be used as acoustically absorbing guide vanes at duct bends or as a fan housing. One important issue for these applications is the effect of flow on the MPP impedance. This issue plus a number of applications related to vehicle noise, have been studied at KTH during the last decade and this paper aims at summarizing the main results.
The effect of flexibility on the acoustical performance of microperforated materials
Authors: Bolton J. S.
Published: September 2012

In conventional models of microperforated materials, the solid layer in which the holes are formed is usually considered to be rigid. However, microperforated materials are often thin, say less than 0.5 mm in thickness, and are sometimes made of lightweight polymeric materials. Experimental measurements suggest that when the mass per unit area of a microperforated material is less than approximately 0.5 kg per square meter, the motion of the solid layer becomes important. The solid layer is driven into motion both by the incident pressure acting on its surface and by viscous forces generated within the perforations. The ability of a microperforate to dissipate acoustical energy depends on there being relative motion between the air in the perforations and the solid layer: motion of the solid may either help or hurt this effect, particularly when the solid layer is supported on a grid-like structure, since the individual segments of the microperforate then exhibit modal behavior. In this presentation, models of this behavior will be described, and examples will be given in which essentially membrane-like behavior is modified by the presence of the perforations, and conversely, in which essentially rigid microperforated layer behavior is modified by vibration of the solid layer.
Partial field decomposition of jet noise using optimally located virtual reference microphones
Authors: Wall Alan T. , Gee Kent L. , Neilsen Tracianne B. , James Michael M.
Published: September 2012

The application of partial field decomposition (PFD) techniques based on a singular value decomposition to jet noise fields is useful for estimating the number of incoherent (equivalent) noise sources within a jet and for implementing near-field acoustical holography, but it does not generally provide physically meaningful partial fields (i.e. partial fields related to individual sources). Among several PFD methods that were designed to generate physically meaningful partial fields, the method developed by Kim et al. [JASA 115(4), 2004] finds the optimal locations of references in a sound field and places virtual references at those locations. In past investigations this method has been successfully applied to locate discrete numerical and physical sources and to generate partial fields related to each source. In this study, Kim’s method is applied to a full-scale jet installed on a military aircraft in an attempt to obtain physically meaningful partial fields. The partial fields obtained using these optimally located virtual references are compared to the partial fields obtained from other PFD methods.
Damping: Some often overlooked facts
Authors: Ungar Eric E.
Published: September 2012

Damping - dissipation of mechanical energy - has significant effects on only some types of vibrations. Damping can result from many mechanisms, many of which cannot readily be modeled, but prediction of details of motions requires correct representations of the dominant mechanisms. The assumption of viscous damping permits one to analyze vibrations via relatively easily solved linear differential equations, but can lead to results that do not represent reality. Several measures of damping are based on simple models involving frequency-independent viscous damping, but realistic damping behavior often may be better represented by a frequency-dependent loss factor. The chemical properties of plastics and elastomers generally are not known well enough to permit assessment of the behavior of such materials without dynamic measurements. Structural configurations with relatively high damping may be obtained by combining high-damping polymeric materials with efficient structural materials only if the configurations are such that for a given deformation the high-damping material stores a considerable fraction of the total mechanical energy. This is manifest in the behavior of free-layer and constrained-layer damping treatments and in their design equations, which also indicate that a damping material that is very good for one of these types of treatments may not be good for the other.
Vibration damping mechanisms for the reduction of sting in baseball bats
Authors: Russell Daniel A.
Published: September 2012

When the impact between a baseball and a bat occurs outside the “sweet-spot” region, the resulting vibration in the handle often produces a stinging sensation in the hands. Pain from a poorly hit ball is primarily felt in the fleshy web between thumb and forefinger in the top (distal) hand, and also to a lesser degree in the heel of the bottom (proximal) hand, and the sensation of sting is more prevalent in aluminum bats than in wood. Several bat manufacturers have attempted to minimize handle vibration in aluminum bats through various methods including handle grips, foam injected into the hollow handle, two-piece construction joining composite handles to aluminum barrels, and the insertion of vibration absorbers in the taper region and in the knob of the handle. This paper will assess and compare the performance of several such vibration damping applications implemented in baseball bats. Experimentally measured damping rates corresponding to the bending mode shapes responsible for sting will be compared for a variety of bat designs. The effectiveness of available commercially implemented damping mechanisms will be compared using frequency response functions and time signals.
Passive acoustic detection and classification of Ziphius cavirostris
Authors: Goldhahn Ryan
Published: September 2012

Cuvier's beaked whales, Ziphius cavirostris (Zc), are a species of marine mammals particularly sensitive to anthropogenic noise. Estimating their habitats and abundance is thus of particular importance when planning and conducting active sonar exercises. Since their deep-diving behavior make them difficult to observe visually, passive acoustics is frequently used for detection. A method of automatic detection and classification of Zc is presented based on the inter-click interval, click spectrum, and direction of arrival estimated on a volumetric array. Specifically, click spectra are compared against a signal subspace constructed from eigenvectors of previously identified beaked whale clicks. The direction of arrival is estimated by cross correlating the received click across a three-dimensional array and clicks are classified based on their estimated elevation angle. Additionally, since Zc are known to produce click trains rather than single clicks, detections made without neighbouring detections are discarded as interference. These three criteria are used to detect and classify Zc, in the presence of dolphin clicks and/or other interference. Results are presented on data collected during the SIRENA10 and SIRENA11 experiments conducted by the NATO Undersea Research Centre in the Atlantic Ocean and Mediterranean Sea respectively, and compared against detections made by human operators and a team of visual observers.
Mode-2 internal wave generation and propagation-impact on acoustic signal properties
Authors: Orr Marshall H. , Evans Thomas E.
Published: September 2012

Mode 2 internal wave spatial distributions, generation, propagation and dissipation in the vicinity of bathymetry variably on the continental shelf and near the shelf break of New Jersey, USA will be overviewed for early fall oceanographic conditions. The 3-D spatial and temporal evolution of the mode 2 waves, as simulated with the Naval Research Laboratory nonhydrostatic Model for Coastal Oceans, will be compared to tow-yo conductivity, temperature and depth (CTD) and high frequency acoustic flow visualization observations of mode -2 internal waves. Sound speed field perturbation and acoustic field spatial and temporal distributions in the presence of mode-2 internal waves will be summarized.
Ecosystem-based management: What would Clay do?
Authors: Jech J. Michael
Published: September 2012

Fisheries resource management is in a state of transition from managing populations at the species level to managing living marine resources at the ecosystem level. This transition will require changes in the way data are collected, analyzed, integrated, and finally utilized in management decisions. C. S. Clay “Clay” was a pioneer in underwater acoustics, but my first experiences and interactions with him were as a graduate student biologist learning to observe and understand the underwater environment in new and innovative ways. Clay’s collaborations with biologists, ecologists, and oceanographers spawned novel methods of integrating and analyzing disparate data sets and many of these methods are being used today. While Clay’s influence on fisheries acoustics has been monumental, his approaches to understanding the ocean environment may be most valuable to ecosystem-based management strategies. I will highlight examples of Clay’s innovative approaches that have been used and ways they could be applied to ecosystem-based management and research.
Architectural acoustics—Space for sound, and you
Authors: Case Alex
Published: September 2012

The discipline of Architectural Acoustics consistently produces more than 100 papers across 6 or more special sessions, at each meeting of the ASA. Student paper awards, student design competitions, and Knudsen lectures augment these activities. Joint sessions, particularly with Noise, Musical Acoustics, Psychological and Physiological Acoustics, and Signal Processing in Acoustics, add more still to the architectural acoustics goings-on at every ASA conference. The sphere of influence is not limited to ASA alone, as TCAA members participate in the Green Construction Code of the International Code Council, Society of Motion Picture and Television Engineers Study Group: Movie Theater Sound System Measurement and Adjustment Techniques, Classroom Acoustics Standards, the American Institute of Architects Continuing Education System, and more. This busy committee also produces a steady stream of publications documenting recent work and deciphering standards for key stakeholders. Anyone with an interest in the field will find many opportunities to advance their own expertise, build a network of colleagues, friends and mentors, and contribute to the essential activities of the Technical Committee on Architectural Acoustics.
Overview of Acoustical Oceanography Technical Committee
Authors: Thode Aaron
Published: September 2012

The Acoustical Oceanography (AO) technical committee focuses on the use of sound to study physical and biological processes in the ocean. The broad scope of the committee ensures that many of the research topics overlap those in Underwater Acoustics and Animal Bioacoustics. This presentation will review representative aspects of AO, including long range acoustic tomography, air-sea interactions via studying bubble plumes, fisheries acoustics, and marine mammal acoustic tracking.
An overview of the Musical Acoustics Technical Committee
Authors: Morrison Andrew
Published: September 2012

The technical committee on musical acoustics (TCMU) is concerned with the application of science and technology to the field of music. Many of the sessions organized by the TCMU focus on a particular family of musical instruments. At many Acoustical Society meetings the TCMU has arranged for musical performances related to one or more special sessions. The TCMU has also arranged for tours of sites in the community around past meeting locations. An overview of what students and relative newcomers to the society can expect from the TCMU in general will be presented as well as highlights of what to see at this meeting.
The Research Organ at the Fraunhofer IBP in Stuttgart
Authors: Angster Judit , Miklós András
Published: September 2012

At the Fraunhofer IBP in Stuttgart a research organ has been built for scientists. Its transparency and unique design allows the demonstration of research results, the investigation of technical and sound problems in organ building as well as the audible testing of sound ideas. Some of the special design features are: The wind system can be switched from traditional to innovative design. Newly developed swell shutters which allow a better dynamic of the sound are mounted in the swell organ. The dimensioning of pipes and wind systems was conducted by means of scaling software developed within the context of European research projects. One wind chest of a division can be exchanged to allow the testing of valves and pipe layouts. In order to test newly designed stops a blind slider is available. There are several blind grooves to analyze the effect of wind flow, of resonances in the grooves and of different outlet holes on the pipe sound. The blowers are driven by a frequency converter for continuous adjustment of wind pressures. The motion of a beating and a free reed can be visualized by means of a stroboscope installed. Some of the research results will be demonstrated.
Aircraft sound transmission in homes categorized by U.S. climate regions
Authors: Ryherd Erica , Firesheets Nathan
Published: September 2012

Current aircraft noise guidelines are based primarily on outdoor sound levels. However, human perception is highly related to indoor response, particularly for residences. A research project is being conducted that provides insight into how typical residential dwelling envelopes affect indoor sound levels. A focus is being placed on non-sonic boom aircraft noise, using continuous noise signatures of commercial aircraft overflights. Typical construction types in various U.S. climate regions have been identified and used to develop model predictions of indoor noise levels. Further, the impacts of systematically altering construction variables such as construction material and window to wall ratio is being investigated. Results will be used to understand trends for expected noise reduction for typical construction types around the U.S.
Wind noise reduction in a non-porous subsurface windscreen
Authors: Zuckerwar Allan J. , Shams Qamar A. , Knight Keith
Published: September 2012

Measurements of wind noise reduction were conducted on a box-shaped, subsurface windscreen made of closed cell polyurethane foam. The windscreen was installed in the ground with the lid flush with the ground surface. The wind was generated by means of a fan, situated on the ground, and the wind speed was measured at the center of the windscreen lid with an ultrasonic anemometer. The wind speed was controlled by moving the fan to selected distances from the windscreen. The wind noise was measured on a PCB Piezotronics 3” electret microphone. Wind noise spectra were measured with the microphone exposed directly to the wind (atop the windscreen lid) and with the microphone installed inside the windscreen. The difference between the two spectra comprises the wind noise reduction. At wind speeds of 3, 5, and 7 m/s, the wind noise reduction is typically 15 dB over the frequency range 0.1-20 Hz.
Noise exposure profiles for small-caliber firearms from 1.5 to 6 meters
Authors: Murphy William J. , Flamme Gregory A. , Zechmann Edward L. , Dektas Caroline , Meinke Deanna K. , Stewart Michael , Lankford James E. , Finan Donald S.
Published: September 2012

Small caliber firearms (rifles, pistols and shotguns) are commonly used at outdoor firing ranges for training in shooting skills, job qualification and for recreation. Firearm noise from fifty-four weapons was measured at an outdoor range in the near field (6 meters and closer) of the weapons using a radial array of 18 microphones centered on the shooter’s head. Each weapon was fired five times and the microphone array was sampled at 200 kHz with at least 16-bit resolution. Peak sound pressure levels and damage risk criteria (e.g. MIL-STD 1474D, 8-hour Equivalent A-weighted Level (LAeq8), and Auditory Hazard Assessment Algorithm for Humans (AHAAH)) were computed for each microphone and compared across weapon type, caliber and load. The acoustic propagation from the muzzle to the microphone was modeled using a simple image source over a reflecting plane. The impedance of the ground was estimated from the observed data and was used to compare the measured waveforms with the estimated waveforms. These data will be used to model the exposures for multiple shooters and observers standing at or behind the firing line.
Wes and Ed and the minus sign—A tale of two giants
Authors: Church Charles C.
Published: September 2012

Once upon a time there was a young lad who liked to stroll through the Land of Bioacoustics. It was a pleasant land filled with many things that this fellow found very interesting indeed, but there were also giants. These giants had powerful names like Wes and Ed, and they understood many things that were hidden from the lad. One of these was how to calculate the force exerted by a traveling wave on an object in an acoustic field. With some trepidation, the fellow asked the giants to explain the proper way to make the calculation. “Certainly lad,” said Wes, “Here’s how to do it.” “Oh,” said Ed, “but what about this?” Each gave him a paper, and he studied them hard, turning them this way and that, and what did he find? The answers were the same. Well almost. One had a minus sign where the other did not. “I don’t understand,” said the lad, “How can this be?” “We’re really not sure,” said the giants, “We’ll have to discuss it. We’ll tell you tomorrow, or in a month or a year.” To learn what they said finally, come to Kansas City to hear.
Planning for a reverberation field experiment
Authors: Tang Dajun , Hefner Brian T. , Williams Kevin L. , Yang Jie , Thorsos Eric I.
Published: September 2012

A basic research reverberation experiment, supported by the US Office of Naval Research, is planned for 2013. Measurement issues that arise when planning such an experiment are discussed. The fundamental requirement for this basic research experiment is that the environment is characterized in sufficient detail to allow accurate numerical modeling of the acoustical results based on the environmental description. The main goal is to measure mid-frequency shallow water reverberation with full companion environmental measurements so that model/data can be compared without ambiguity. Included in the goal is to make statistical estimates of the uncertainties associated with all the environmental conditions. The frequency range of interest is 1-10 kHz with emphasis at 3 kHz. A pilot field experiment was conducted off the coast of Panama City, Florida. Data from the pilot experiment will be discussed in light of the forthcoming main experiment, including simulations on both propagation/forward-scatter and reverberation for given noise background on both vertical and horizontal arrays which will be deployed in the main experiment.
Some initial findings from the very shallow water GulfEx12 reverberation experiments
Authors: Preston John R.
Published: September 2012

In April 2012, reverberation and clutter measurements were taken in very shallow water (~20 m) over a 40 hour period off Panama City, FL. This work describes the data from this recent sea trial called GULFEX12 designed to characterize reverberation and clutter from a very shallow water site in the 2500-5500 Hz band. The received data are taken from one aperture of the Five Octave Research Array (FORA) namely, the triplet sub-aperture. The array was fixed 2 m off the sea floor by mounting it to tripods using a clothes line and data were passed by cable to a nearby moored ship (the R/V Sharp). An ITC source transducer was located 3 m away from the array center. Data show a surprising amount of anisotropy. Five different pulses were used in this study. Matched filtered polar plots of the reverberation and clutter are presented using the FORA triplet beamformer to map out anisotropy. Some model data comparisons are made using the author?s normal mode based reverberation model. Help from D.J. Tang, T. Hefner and K. Williams of Applied Physics Lab at Univ. of Washington was crucial to this effort. [Work supported by ONR code 322OA.]
Modeling binaural suppression processes for predicting speech intelligibility in enclosed spaces
Authors: Li Vanessa , Xiang Ning , Braasch Jonas
Published: September 2012

Speech from a target speaker reaches a listener via multiple paths in a room due to room reflections. As sound waves from the target speaker approach the listener, degradation to the signal is caused by ambient noise and reverberant energy. The speech transmission index (STI) is a commonly used metric for predicting speech intelligibility accounting for both noise and reverberation. This metric, however, is a monophonic measure that does not take into consideration binaural cues used for unmasking undesired effects. As a result, using the STI on its own tends to under-predict intelligibility under binaural listening conditions. The proposed research aims to improve speech intelligibility predictions with the presence of room effects by implementing a psychophysical binaural model as a front-end to the STI calculation. The equalization-cancellation (EC) theory is applied to spatially unmask noise, while late incoherent reverberant energy is suppressed by applying a weighting function based on interaural coherence. Preliminary comparisons between listening tests and model predictions reveal promising results, indicating a useful tool in acoustical planning in addition to further study into binaural suppression processes.
Comparison of headphone- and loudspeaker-based concert hall auralizations
Authors: Clapp Samuel , Guthrie Anne , Braasch Jonas , Xiang Ning , Caulkins Terence
Published: September 2012

In this research, a spherical microphone array and a dummy head were used to measure room impulse responses in a wide variety of concert and recital halls throughout New York State. Auralizations were created for both headphone playback and second-order ambisonic playback via a loudspeaker array. These two systems were first evaluated objectively to determine the level of accuracy with which they could reproduce the measured soundfields, particularly with respect to important binaural cues. Subjects were then recruited for listening tests conducted with both reproduction methods and asked to evaluate the different spaces based on specific parameters and overall subjective preference, and the results of the two playback methods were compared.
Applying direct algebraic sound source localization method for time-domain reflectometry of conference room
Authors: Levy Tsukassa , Ando Shigeru
Published: September 2012

A novel localization method has been previously exposed, using an explicit formula of direction and distance of a monopole source and a circular array [S. Ando, ASA Seattle Meeting, 2011]. However, this localization method has little been applied in real environments, such as concert halls or conference rooms. It has also been shown that the algorithm has a high temporal resolution [T.Levy, S. Ando, Hong Kong Acoustics 2012, 2012] that enables to localize sound sources using reflected sound waves. Thus, the aim of this study is to study conference room’s reflection using the proposed algorithm and to test its robustness and its efficiency in such conditions. In the experiments, the main reflectors in the conference room will be identified and a comparison between the previously proposed method and the traditional sound source localization algorithms is done, in terms of rapidness and precision.
Long-term acoustic monitoring off Central California
Authors: Collins Curtis A. , Joseph John E. , Chiu Ching Sang , Colosi John , Miller Christopher W.
Published: September 2012

The use of moored ocean arrays for environmental acoustic measurements off Central California is discussed. A cabled array off Point Sur, CA, which was designed for long-range, low-frequency listening was used by NPS and collaborators from late 1997 through mid-2000 and provides examples of a wide range of activities including use for student laboratories, faculty and student research, as well as monitoring, e.g. ambient acoustic noise, test ban treaty activities. From mid-2006 to present, passive acoustic data have continued to be collected off Pt. Sur using single hydrophone moored autonomous listening stations which record data intermittently at sampling rates of 200 kHz. We have recently considered re-establishment of cabled passive acoustic measurements using MARS, an example of an observatory which was designed and located for more traditional oceanographic studies. The utility of MARS for acoustic measurements depends both on how well it can characterize the regional acoustic environment as well as local oceanographic processes that can be resolved acoustically (canyon effects, geography, sound speed variability, sediments and local vessel traffic). These can be contrasted with existing cabled and autonomous data from Point Sur.
The power of acoustics in ocean observing systems: A case study in the Bering Sea
Authors: Miksis-Olds Jennifer L. , Madden Laura E.
Published: September 2012

Acoustic time series are incredibly powerful as independent data sets. Passive acoustic recordings provide information on environmental sound levels, the presence of vocalizing animals, surface conditions, marine precipitation, and anthropogenic activities within the area of acoustic coverage. Active acoustic systems provide a time series of acoustic backscatter from which biological scatter can be measured and quantified to provide estimates of relative abundance and numerical density. The combination of acoustic technology with other hydrographic sensors within an ocean observing system now affords the opportunity to develop an understanding of ecosystem dynamics ranging from the physical oceanographic conditions to the distribution and behavior patterns of top predators. This is especially critical in sub-Arctic regions like the Bering Sea where rapid changes associated with climate change are having impacts at multiple levels. Here we discuss the environmental parameters that are the best predictors of different marine mammal species as determined through generalized linear and general additive mixed models. Predictor variables considered were percent ice cover, ice thickness, sound level at five frequencies, and percent composition of 4 biologic scattering groups.
Numerical schemes for the Iterative Nonlinear Contrast Source method
Authors: van Dongen Koen W.A. , Demi Libertario , Verweij Martin D.
Published: September 2012

Nonlinear acoustics is gaining importance for medical acoustical imaging and high intensity focused ultrasound. With the latter one, high-amplitude acoustic wave fields are used to damage or kill cancer cells. For accurate treatment planning, a full-wave method which can model the propagation and scattering of the nonlinear field in attenuative, heterogeneous media is required. The Iterative Nonlinear Contrast Source (INCS) method is a full-wave method originally developed for homogeneous medium. It recasts the Westervelt equation into an integral equation which can be solved using a Neumann scheme. For heterogeneous media, the same approach results in additional contrast source terms. When these additional contrast sources become strong, convergence of the Neumann scheme may become an issue. To overcome this problem, the Westervelt equation may be linearized and the resulting linear integral equation may be solved with more advanced schemes such as Bi-CGSTAB. Restart strategies may be applied to eliminate systematic errors in the higher harmonics caused by the linearization. However, for realistic wave speed contrasts convergence remains problematic. To overcome these limitations, schemes such as steepest descent may be applied on the original nonlinear integral equation. In the present talk, the different schemes and their pros and cons will be discussed.
Liquid compressibility effects in the dynamics of acoustically coupled bubbles
Authors: Thomas Derek C. , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: September 2012

Accurate models for clusters of interacting bubbles are sought for both biomedical and underwater applications. Multiple bubble models have been developed by treating the bubbles as a system of interacting oscillators. The models are obtained initially for bubbles in an incompressible, irrotational, and inviscid liquid; additional effects are included in an ad hoc fashion. The existing oscillator models for the dynamics of interacting bubbles are improved by including the effect of liquid compressibility. In particular, while existing models have been improved by including propagation delays in the bubble interactions, the effect of bubble interaction on radiation damping has not been considered. The current work develops corrections for the radiation damping of coupled bubbles in both linear and nonlinear models of bubble dynamics. These corrections eliminate certain instabilities that have been observed in delay differential equation models of coupled-bubble dynamics. Additionally, an increase in the coupling strength between bubbles undergoing high-amplitude radial motion is predicted when coupled radiation damping is included; this increase in coupling strength strongly affects the predicted motion of the system and the resultant pressure in the surrounding medium. [Work supported by the ARL:UT McKinney Fellowship in Acoustics and NIH DK070618.]
Real-time audio signal capture and processing using matlab object oriented programming
Authors: Hosakere Shivaswamy Samarth , Zhou Xiang , Roessner Stephen , Ren Gang , Headlam Dave , Bocko Mark
Published: September 2012

In MATLAB programming language the real-time audio processing functions are usually simulated in non-real-time due to a lack of real-time audio programming support. As a result the real-time audio signal capture and processing functionalities are usually implemented in other programming languages and cannot utilize the extensive signal processing functionalities provided by MATLAB. In this paper we introduce a MATLAB real-time signal processing framework based on MATLAB timer object and audiorecorder object. The proposed processing framework serves as an alternative solution for real-time programming implementation and demonstration. In our proposed processing framework the timer object is implemented to handle the looping of processing cycle, schedule the signal processing tasks, and handle the error processing. The audio capturing/processing functionality is implemented in the timer cycle by using two audiorecorder objects that read the audio streaming data and feed a segment of data to signal processing alternatively. The proposed framework achieves satisfactory real-time performance with no missing audio frames when a short audio delay setting of 10ms is applied. Several application examples of our proposed framework are also demonstrated.
Soundscape analysis of two parks in Berlin
Authors: Manrique-Ortiz Natalia , Schulte-Fortkamp Brigitte
Published: September 2012

Nowadays the protection of quiet areas is an issue of increasing importance. This importance is reflected in the European directives and policy intentions of many countries around the world. In order to protect this areas, is important to characterize their soundscapes and analyze the areas, paying special attention to the geography, aesthetics, social, psychological and cultural aspects, since these aspects play a significant role in the noise perception. The aim of this research is to analyze two of the most important Berliner parks. Victoria-Park and Schlosspark are located in very different areas in Berlin. Schlosspark is in a more quiet neighborhood with families and Victoria-Park is in a lively, young and multicultural neighborhood. The protection of these parks begins understanding the community who make use of them. The research will be based on interviews and soundwalks according to the soundscape approach. The results will be presented.
Investigation of tranquility in urban religious places
Authors: Hwang Inhwan , Hong Jooyoung , Jeon Jin Yong
Published: September 2012

In the present study, tranquility in urban religious places including a cathedral and a Buddhist temple has been assessed by soundwalks. Both Myung-dong Cathedral and Bongeun Temple located in the center of Seoul were selected as measurement sites. During the soundwalks, audio-visual recordings were conducted at selected positions. From the field measurements, the temporal and frequency characteristics of the sound environment in two religious places were explored. Participants evaluated their perceived soundscape using a soundwalk questionnaire along the soundwalk routes in the church and temple gardens in order to investigate the value of tranquility as urban stress relievers. From the results, indicators representing tranquility difference in particular soundscapes were examined.
Preston Smith and waves in a cylindrical shell
Authors: McDaniel James G.
Published: September 2012

In 1955, Preston Smith wrote a landmark paper on free waves in a cylindrical shell. That paper described the displacement components and dispersions of the flexural, shear, and longitudinal waves that propagate in helical directions in the wall of the cylinder. The present author first met Preston over forty years later, when the hand calculations of 1955 had been transferred to a computer. After that meeting in 1996, the group at BBN was interested in how these waves reflect from terminations. Preston developed an approach for solving this problem and worked with the group to implement it using finite element analysis of a cylindrical shell with terminations. The essence of the approach was to mechanically excite different mixtures of waves using different excitations. The amplitudes of incident waves were related to the amplitudes of reflected waves by a reflection matrix. This matrix quantified the wave conversion that occurs at shell terminations. In addition, Preston formulated the reciprocity conditions that must be satisfied by the reflection matrix. His work revealed the most important physics of a very complex system. The present lecture will describe his approach and will highlight his profound style of analysis.
Vibrational response features of a locally excited fluid-loaded plate with attached mass-spring oscillator systems
Authors: Feit David
Published: September 2012

Preston Smith and others have examined the radiation features of locally excited plates that are periodically supported by inertial masses. This presentation looks at the vibrational response and on-surface pressure field of a locally excited fluid-loaded plate that has one or more attached mass-spring oscillators. The analysis makes use of the "rational function approximation" (RFA) representation of the fluid loading effect first introduced by Diperna and Feit (J. Acoust. Soc. Am. 114(1), July 2003, pp. 194-199).
Preston Smith's theory of the effect of heat radiation on sound propagation in gases
Authors: Pierce Allan D.
Published: September 2012

The 1996 Trent-Crede Medal encomium by Barger states that Smith's favorite paper was "Effect of heat radiation on sound propagation in gases" (JASA, 1957). Smith stated this also in a private communication some time earlier to the present writer. The paper was prompted by works by Stokes and Rayleigh in which heat effects were modeled by Newton's law of cooling, which presumes that the heat radiation out from a limited region of heated matter is proportional to the difference of the local temperature and that of the surrounding medium. Stokes in 1851 constructed a theory for how this assumption leads to a prediction of the dependence of phase velocity and attenuation on frequency, and this theory was used by Rayleigh in the Theory of Sound to analyze whether acoustical fluctuations were more nearly isothermal or adiabatic. However, as Smith pointed out, apparently for the first time, neither Stokes and Rayleigh fully understood the relevant physics. When the atomic nature of heat radiation within gases is taken into account, the effect of heat radiation (in contrast to the effect of thermal conduction) is negligible at all frequencies. For all frequencies for which the attenuation is small, the acoustic fluctuations are adiabatic.
Delayed feedback disrupts optimal strategies during foreign speech sound learning
Authors: Chandrasekaran Bharath , Yi Han-Gyol , Maddox W. Todd
Published: September 2012

The Competition between Verbal and Implicit Systems (COVIS) model posits that an explicit hypothesis-testing system competes with an implicit procedural-based system to mediate category learning. During early learning, the hypothesis-testing system is dominant, whereas in later learning, the procedural system dominates. In visual category learning, delayed feedback is known to impair the procedural but not the hypothesis-testing system. We tested the COVIS model in natural auditory category learning. Young adult native English speakers learned to categorize lexical tones in Mandarin syllables. Timing of feedback was either immediate (0 s) or delayed (500 or 1000 ms). Consistent with COVIS, delay feedback affected accuracy only in later learning. Further, modeling analysis revealed that participants were more likely to adopt procedural strategies during later learning, but this transition was disrupted by delayed feedback. These results will be discussed in the context of developing methods to optimize foreign speech sound learning.
Training adult learners of English to hear the sounds of English
Authors: Watson Charles S. , Miller James D. , Kidd Gary R.
Published: September 2012

Adult students of foreign languages frequently claim that native speakers of that language speak too rapidly. This is likely a result of the students’ failure to achieve automaticity in recognition of speech sounds necessary for effortless speech perception. Research on the time course of auditory perceptual learning for both speech and non-speech sounds provides strong evidence that adults can, with appropriate training, achieve perceptual skills approximating those of native speakers, although they only rarely do so. Among the few adults who do achieve near-native conversational skills in an L2, many have had intensive recognition practice and training. The Speech Perception Assessment and Training System for students of English as a Second Language (SPATS-ESL) of CDT, Inc. provides such training. SPATS-ESL trains the identification of the 109 most common English syllable constituents (onsets, nuclei, and codas) and the recognition of meaningful sentences spoken by a variety of native speakers. Based on experience with over 200 ESL learners it has been found that near-native performance in the recognition of discrete English speech sounds and meaningful sentences spoken by many talkers is acquired by most ESL students after 15-30 hours of individualized computer-based training. (Watson and Miller are stockholders in CDT, Inc.)
High variability training increases mismatch negativity responses to L2 contrasts
Authors: Herd Wendy , Fiorentino Robert , Sereno Joan
Published: September 2012

Previous research established that high variability training improves both perception and production of novel L2 contrasts and that training noncontrastive sounds in subjects’ L1 results in increased MMN responses to those sounds. However, it is unclear whether training novel contrasts in an L2 also results in increased amplitude of MMN responses to the contrasts. This study trained 10 American English learners of Spanish, for whom tap and /d/ are noncontrastive, to distinguish the phonemic tap-/d/ contrast in Spanish to determine if training also changed MMN responses to those sounds when presented in an oddball paradigm. First, the amplitude of native Spanish speakers’ (N=10) MMN response to deviant tap was significantly more negative than to the standard, establishing this paradigm elicited canonical MMN responses. Second, trainees (N=10) and controls (N=10) did not exhibit significantly different responses to deviant and standard tap at pretest. Crucially, this was not the case at posttest. Trainees, like native Spanish speakers, exhibited a significant MMN response to deviant tap compared to the standard at posttest, but controls did not. The emergence of an MMN response in the trainees indicates it is possible to recategorize L1 contrasts when learning an L2. [Supported by NSF 0843653.]