bluuebunny/crossref_metadata_2025 huggingface dataset:
The violin: Perceptual studies and acoustical correlates.
Authors: Fritz Claudia
Published: March 2010

This talk discusses the results of experiments in which performances were replayed on different “virtual violins” in order to explore the relationships between acoustical characteristics of violins and perceived qualities. Specifically, it explores perceptual observations reported by Dünnwald [based on his measurements of over 700 instruments, J. Catgut. Acoust. Soc. (1991)] by modifying the amplitude of the resonance modes over five octave bands (thereby covering the violin’s entire register). When using a subset of the most distinctive verbal descriptors of violin timbre [Fritz et al., Conference of Interdisplinary Musicology (2009)] to study the relationship between human perception and these acoustical modifications, we ascertained results that partially conflict with Dünnwald’s observations. In addition, the study investigated the manner by which one’s perception of the violin’s tone quality is affected by the magnitude of a player’s vibrato as well as the damping of the violin’s resonant modes. Our results do not support the conclusion that liveliness results from the combination of the use of vibrato and a “peaky” violin response. The talk concludes by discussing the limits of such psychophysical studies, suggesting future directions for psycholinguistic-based research in this domain.
Optimizing the taper-camber relationship in bows for string instruments.
Authors: Graebner John E. , Pickering Norman C.
Published: March 2010

A violin bow’s taper (graduated diameter) and camber (inward or concave pre-bending of the stick) are important tools used by expert bow makers who know by intuition and experience how to match the two parameters. We have analyzed the static forces in bows and constructed a mathematical model that reveals a simple relationship between taper and camber. For any given taper, the model predicts a preferred camber and vice versa. A machine has been constructed for accurately measuring the diameter and camber profiles, and measurements on several dozen bows of various degrees of playability provide support for the model.
A method for measuring indoor noise levels from traffic with ulterior noise sources.
Authors: Oldakowski Daniel
Published: March 2010

This paper describes a measurement protocol used to determine indoor noise levels due to motor vehicle traffic traveling on Route 395/Route 295 flyover in southeast Washington, DC. Measurements were taken over a period of 24 h, in multiple locations of a 14-story high rise building, located in the vicinity of a baseball stadium. The challenge was to remotely measure the indoor noise due to traffic in the presence of unknown and unpredictable such as construction activity inside and outside the building during the day and nearby baseball field activity at night. Multiple sound level meters were employed, inside and outside the building. One-third octave band data, with a 1-min resolution, were taken for the duration of the measurement, as is typical for indoor noise measurements. Partial recordings of the sound field time history within the building were taken to document “loud” events. During postprocessing, loud events were manually inspected to determine if those events were due to traffic noise or due to other noises.
Developing a basis for efficient railroad horn testing.
Authors: Erdreich John , Keefe Joseph
Published: March 2010

In response to complaints of excess noise from residents living in the vicinity of rail grade crossings, the Federal Railroad Administration promulgated regulations mandating minimum and maximum horn sound output levels. Older fleets require testing of horns to ensure compliance with these limits. Test requirements (no reflecting surfaces within 200 ft of the horn; wind less than or equal to 12 m/ph; no precipitation) severely limit the ability of urban commuter railroads to comply with the testing, especially in northern and coastal areas. To develop an alternate test protocol, measurements of horn sound levels were carried out in a semi-anechoic chamber and outdoors to determine if a reliable transfer function could be constructed to convert the chamber measurements to the outdoor measurements. Standard deviations of the A-weighted chamber measurements were smaller than standard deviations of the outdoor measurements. For one fleet, the differences between chamber measurements and outdoor measurements resulted in a consistent difference of about 41 dB(A). Locomotive supply air pressure differences at the horn were not a significant factor in sound output.
Transient in cab noise investigation on a light duty diesel passenger vehicle.
Authors: Purekar Dhanesh
Published: March 2010

A diesel engine in cab sound quality for passenger car market is scrutinized more closely than in the mid- to heavy duty diesel truck applications. This is obviously due to the increasing expectations from the customers for gasolinelike sound quality. This paper deals with a sound quality issue recently investigated on a light duty diesel engine for a passenger van application. The objectionable noise complaint occurred during the vehicle transient operating conditions and was found to be caused by the change in the pilot quantity over a very short period of time. The root cause of the noise complaint was investigated on the noise complaint vehicle as well as simultaneously on a standalone engine in the noise test cell. Several critical combustion and performance parameters were recorded for diagnosing the issue. In addition, various standard sound quality metrics were employed to differentiate the sound quality of the objectionable noise. The issue was resolved and verified by making appropriate changes to the engine calibration without affecting key requirements such as emissions and fuel economy. Finally, the findings from the experimental tests are summarized and appropriate conclusions are drawn with respect to understanding, characterizing, and resolving this transient, combustion related impulsive powertrain interior noise issue.
Low wavenumber turbulent boundary layer fluctuating wall shear stress measurements from vibration data on a cylinder in pipe flow.
Authors: Bonness William , Capone Dean , Hambric Stephen
Published: March 2010

Fluctuating wall shear stress under turbulent boundary layer (TBL) excitation is studied in this experimental investigation. A cylindrical shell with a smooth internal surface is subjected to TBL excitation from water in fully developed pipe flow at 6.1 m/s. The vibration response of the cylinder is used to inversely determine low-wavenumber TBL shear stress levels. Both the cross-flow and streamwise directions are examined using directionally uncoupled low-order cylinder modes in the circumferential and axial directions. These data address a critical gap in available literature regarding experimental low-wavenumber shear stress data. The low-wavenumber shear stress levels in both the cross-flow and streamwise directions are determined to be roughly 10 dB higher than those of normal pressure. As is the case for various models of TBL pressure, these measurements suggest that a nearly constant value for normalized shear stress at low wavenumber is valid over a broad range of frequencies. A simple wavenumber white model form established for low-wavenumber TBL surface pressure is also shown to be appropriate for shear stress.
Analysis of sound measurements inside a finite length ducted rotor system.
Authors: Morris Scott , Tomko Jason , Stephens David
Published: March 2010

The sound generated by a ducted rotor system leads to a complicated acoustic field inside the duct. The source can have both broad-band and tonal sound features. The interior Green’s function will add additional complexity due to the cut-on modes and finite-length (organ pipe) effects. In this study, a simple ducted rotor was considered experimentally and analytically in order to obtain observations and predictions of these features. The results will be an important component of modeling the structural vibration in systems where the rotor operates in an elastic shell.
Aero-acoustic predictions of automotive dashboard HVAC (heating, ventilating, and air-conditioning ducts).
Authors: Detry Stephane , Manera Julien , Detandt Yves , d'Udekem Diego
Published: March 2010

The flow-induced noise generated by automotive climate control systems is today emerging as one of the main noise sources in a vehicle interior. Numerical simulation offers a good way to analyze these mechanisms and to identify the aerodynamic noise sources in an industrial context driven by permanent reduction in programs timing and development costs, implying no physical prototype of ducts before serial tooling. This paper focuses on a numerical aeroacoustic study of automotive instrument panel ducts to estimate the sound produced by the turbulent flow. The methodology is the following: the unsteady-flow field is first computed using a CFD solver—here FLUENT. Then, the acoustic finite element solver ACTRAN computes the acoustic sound sources from these time domain CFD results. The sources are finally propagated into the vehicle interior in the frequency domain. One advantage of the technique is that the CFD computations are completely separated from the acoustic computations. This allows reusing one CFD computation for many different acoustic computations. The theoretical background is presented in the first sections of this paper. Then, the accuracy of the method for real industrial cases is demonstrated by comparing the numerical results to experimental results available at VISTEON.
Frequency-dependent propagation characteristics in and around forests.
Authors: Swearingen Michelle E. , Albert Donald G. , White Michael J. , Guertin Patrick
Published: March 2010

Sound propagation in and around forests is highly influenced by the unique vegetative environment. The array of scattering objects represented can be parametrized by parameters such as tree height and diameter, spatial arrangement, and areal density. The array can be in a lattice or random configuration, depending on whether the trees were intentionally planted or naturally occurring. The trees themselves can be of uniform age and size or a mixture of sizes and types. Using data from three different study areas, this presentation will explore correlations between the physical structure of the forest and frequency-dependent attenuation of impulsive sounds.
Meteorological influence on highway noise barrier performance: A case study.
Authors: Burgé Paul , Sytsma Jon , Zurburg Tom
Published: March 2010

Local meteorological conditions such as cross-winds and temperature gradients have long been recognized as factors that can negatively affect noise barrier performance. However, this relationship is seldom demonstrated with empirical data and neither are prevailing meteorological conditions routinely taken into consideration in the design of highway noise barriers. In this case study, a post-construction acoustical investigation was undertaken for a barrier that was installed as part of a recent highway improvement project and where neighborhood residents persistently complained that the barrier was not providing expected noise reduction. Several days worth of noise level measurements and meteorological data were collected and analyzed. The results of the analysis indicated that, while the area residents were not actually impacted under applicable federal and state noise policy, the noise barrier performance was indeed being significantly influenced by documented meteorological conditions. Interaction with area residents also revealed a remarkable example of the wide variation in different individuals’ subjective response to virtually the same noise environment.
A numerical study of impulse propagation over a hill.
Authors: Parakkal Santosh , Di Xiao , Gilbert Kenneth E.
Published: March 2010

In preparation for a field experiment, a numerical study of impulse propagation over a hill has been carried out. The near side of the hill corresponds to downward refraction with the associated ducted propagation. The far side of the hill corresponds to upward refraction with the associated shadow zone. Thus conditions corresponding to nighttime propagation (downward refraction) and daytime propagation (upward refraction) can be studied in the same experiment. Of particular interest is the propagation of surface waves over the hill and into the shadow zone on the far side of the hill. For selected values of hill curvature and ground impedance, numerical predictions are presented and discussed in relation to the envisioned experiment. [Research supported by the U.S. Army TACOM-ARDEC at Picatinny Arsenal, New Jersey]
Portable loudspeaker coverage capability for in-situ outdoor performance spaces.
Authors: Arvelo Juan , Johnson Shawn , Mitnick Ronald
Published: March 2010

Observations from daily experiences reveal that sound propagation in air is influenced by the ground topography, atmospheric stratification, winds, and turbulences. A ray-based outdoor loudspeaker coverage model was developed that accounts for terrain and atmospheric conditions. Loudspeaker coverage may be adjusted to various levels of sound or speech intelligibility. Comparison against benchmark closed-form solutions and wave-based approaches demonstrate the accuracy and computational efficiency of this Gaussian-ray bundle model at aural frequencies. This model is well suited as an acoustic design aid for outdoor performance spaces. This software was packaged into an ultra-mini notebook computer with an integrated GPS antenna and a 90-m resolution worldwide terrain database to account for in-situ terrain effects on sound propagation, a built-in microphone for calibrated measurement of the background noise level and the loudspeaker source level, and a USB real-time logger of temperature and relative humidity. The model is also capable of importing atmospheric measurement from balloon-launched radiosondes and various atmospheric models to accurately account for atmospheric stratification in temperature, pressure, relative humidity, wind speed, and direction in forensic investigations. Atmospheric turbulence has been shown to be another important factor that must be included in the next generation portable loudspeaker coverage capability.
Modeling the acoustic interaction between components in ventilation ductwork.
Authors: Kirby Ray
Published: March 2010

The modeling of sound propagation in ventilation systems normally focuses on understanding the acoustic performance of individual components within the system. For example, theoretical models have long been available for ventilation silencers, elbows, branches, and bends. However, to fully understand the overall acoustic performance of a system, it is necessary also to investigate the interaction between these components. This may be achieved by using numerical methods such as the finite element method and in principle current commercial packages may now be used to examine multiple components in ventilation systems. However, commercial packages normally rely on meshing the entire ventilation system and the computational cost of such an approach quickly becomes prohibitive at higher frequencies. An alternative, and computationally more efficient, approach is to use a modal expansion for the sound pressure field in uniform duct sections and to apply a full finite element analysis only to non-uniform elements, such a corners and/or branches. Accordingly, predictions for a ventilation system that contains multiple components are reviewed here, and the acoustic interaction between these components is examined in order to gain a better understanding of the in situ acoustic performance of important components such as the ventilation silencer.
Numerical and experimental investigation of sound transmission of a tee-junction in a rectangular duct at higher-order modes.
Authors: Lau Siu-Kit , Leung Kwan-Hao
Published: March 2010

Sound transmission and scattering properties in higher-order modes across the tee-junction of a rectangular duct used in ventilation and air-conditioning system were investigated numerically and experimentally. High-sound transmission of the fundamental mode and higher-order modes across the main duct is observed at eigen-frequencies of the main duct. The resonance of branch modes is suppressed by the weak modal coupling of the branch-modes and the traveling wave in the main duct at or very close to the eigen-frequencies of the sidebranch, which results in high-sound transmission of the fundamental mode and higher-order modes across the main duct and excitation of the branch modes at higher frequencies. Increases in sound scattering into higher-order mode are found when the non-planar or longitudinal branch-mode excited. In the case of co-excitation of the longitudinal branch-mode and non-planar branch-modes, a broader band-stop action in sound transmission has been observed. The results of numerical simulations were verified by experiments. A formulation of a transmission matrix based on the transfer function and a two-microphone method was shown. [The work described in this paper was supported by a grant from the Hong Kong Polytechnic University (Project A/C Code: G-U362).]
Evaluating the prevalence of masking as a causal factor in wildlife responses to noise.
Authors: Barber Jesse , Fristrup Kurt M.
Published: March 2010

Many protected natural areas are chronically exposed to noise. Noise exposure grows faster than the human populations whose activities generate noise. Data accumulate regarding masked hearing performance in animals, which can be coupled with models of sound propagation to predict reductions in the spatial extent of auditory awareness with elevated background sound levels. The emergence of predictive models of noise masking effects recommends a reassessment of field studies of wildlife responses to noise to identify the potential scope of this problem. A review of this literature reveals a substantial and diverse collection of scientific papers whose findings are plausibly related to masking effects and an increasing number of more decisive results from studies that were designed to control for other confounding factors.
An approach to making safe and secure indoor soundscape measurements.
Authors: Good Kenneth , Roy Kenneth
Published: March 2010

Outdoor soundscape measurements are being done for many types of noise sources and locations, and the monitor equipment must be both durable and secure from both the elements and physical disturbance. Indoor measurements require a somewhat more sophisticated setup since the measurement space is often an occupied space, and in the case of hospital corridors these will likely be very active spaces 24/7. A creative yet simple approach to setting up monitor stations in hospital hallways, nurses stations, and patient rooms was developed and is being used in a number of research programs. It is imperative that valid noise measurements be made in the designated spaces without arousing undue concern or interests on the part of the occupants (both medical professionals and patients/families), and that the equipment be unobtrusive and thus secure. Monitor system mounting technique and measurement performance will be illustrated and discussed.
Description and comparison of healthcare sounds.
Authors: Davenny Benjamin C. , Unger Gladys L.
Published: March 2010

Within the clinical literature and the popular press, the noise from particular pieces of healthcare equipment or certain clinical environments is described by giving an example that is supposed to orient the reader. But these examples are often very misleading and may be in inappropriate. Outdoor everyday sounds are compared with interior healthcare sounds and steady sounds are compared with impulsive sounds. This discussion will explore better descriptions of healthcare and everyday sounds with the goal of providing better comparisons. Illustrated by examples currently in the literature we will discuss what constitutes a useful comparison and what attributes of the sounds need to be considered. Better descriptions of healthcare noise sources will help in the control of hospital soundscapes.
Acoustic privacy and health care.
Authors: Moiseev Neil
Published: March 2010

Acoustic privacy can be differentiated into two categories: freedom from intrusive noise, such as a person snoring or wheezing in the next bed, traffic outside the windows, carts in the hallways, and footsteps on the floor above; and speech privacy—the freedom from being overheard and of overhearing others. Providing the proper acoustical environment and the protecting privacy must be a joint effort between the facility designers and hospital staff. A brief discussion of the basic requirements for speech privacy and HIPAA privacy and a quality background sound will be presented.
Two healthcare buildings get the power, the noise, and the vibration from a gas turbine generator system.
Authors: Himmel Chad N.
Published: March 2010

A package gas turbine generator was installed at a small, 4.3-MW cogeneration power plant of a mixed use development with office, retail, hospital, residential, and other occupancies. Shortly after commissioning, noise complaints were received from nearby medical offices about undesirable tonal noise intrusions. At another nearby hospital building, a neurosurgery suite addition would include a new intra-operative magnetic resonance imaging (iMRI) unit. Ambient vibration measurements at that site indicated prominent discrete frequencies of disturbance that could affect iMRI image quality. Investigations found loud broadband noise and dominant ground borne vibration in the vicinity of the turbine, with strong tonal peaks relating to turbine and generator rotational rates. The intrusive noise in nearby medical offices and the structure borne vibration at the hospital included matching strong tonal peaks. Various noise- and vibration-mitigating measures were proposed and some were implemented with successful results for the medical offices and new iMRI suite. Mitigating measures are discussed, along with measurement results and photographs.
Substructural organization and acoustic harmonic generation in fatigued metals.
Authors: Cantrell John H.
Published: March 2010

Since the discovery of acoustic harmonic generation in solids by Breazeale and Thompson [Appl. Phys. Lett. 3, 77 (1963)] and Gedroits and Krasilnikov [Sov. Phys. JETP 15, 122 (1963)], nonlinear acoustics has gained popularity as a tool for nondestructive materials evaluation. A longstanding problem has been the assessment of fatigue damage. Harmonic generation measurements are shown to provide for the first time a quantitative, unambiguous means to assess the state of fatigue in metals from the virgin state to fracture. The salient features of an analytical model are presented that account for the microelastic-plastic nonlinearities resulting from the interactions of an acoustic wave with self-organized dislocation substructures and cracks that evolve during cyclic loading. The model predicts a monotonic increase in the nonlinearity parameter of several hundred percent over the life of the material. Generally, the increase in the nonlinearity parameter during the first 80%–95% of fatigue life is dominated by the evolution of organized dislocation structures, while the last 5%–20% is dominated by crack growth. Applications of the model to aluminum alloy 2024-T4, 410Cb stainless steel, and IN100 nickel-base superalloy yield excellent agreement between theory and experiment.
Nonlinear acoustics: A transition from laboratory to a practical fatigue assessment tool.
Authors: Na Jeong-Kwan
Published: March 2010

The ultrasonic second harmonic generation technique measuring the nonlinearity parameter has been developed and used in laboratories for several decades throughout the world. Many students and visiting scholars from numerous countries devoted their passions at the physical acoustics laboratories led by Dr. Mack Breazeale for 50 years. During that period of time, nonlinear elastic properties of single crystals, polycrystalline alloys, superconductors, ceramics, and composites were measured. New measurement systems and techniques were also developed to understand temperature dependent linear and nonlinear elastic behaviors of these materials over a temperature range from the liquid helium to Curie temperatures of piezoelectric ceramics. It took years of research and development efforts with a persistent funding before a practical fatigue damage measurement technique was finally developed. The transition from a rack full of equipment to a portable fatigue damage measurement system, a continuous iteration process was inevitable. The current system, specifically designed for steam turbine blades fatigue inspections, consists of a probe fixture and an industrial grade lunch-box computer with custom designed signal processing cards.
Peculiarities of acoustic beam reflection from a fluid-solid interface.
Authors: Sapozhnikov Oleg A. , Karabutov Alexander A. , Mozhaev Vladimir G.
Published: March 2010

Mack Breazeale and his colleagues published several papers on experimental study of non-specular reflection of ultrasonic beam from a fluid-solid interface [Breazeale et al., J. Acoust. Soc. Am. 56, 866 (1974); J. Appl. Phys. 48, 530 (1977)]. To study fairly unusual details of the reflected beam structure, Schlieren visualization was employed, which clearly confirmed theoretical predictions. The present talk was motivated by this elegant approach of Breazeale. One of the goals was to improve reflected beam imaging by using pulsed Schlieren technique. The second goal was to observe a growing interface wave. It is known that the secular equation for acoustic waves at fluid-solid interfaces yields the common leaky wave and its complement. This complementary wave grows instead of decays with propagation and is time-reversed compared to the leaky wave. Ultrasonic pulses and their reflections were visualized using Schlieren imaging and stroboscopic flashing of a semiconductor laser. The source was a broadband (0.5–3 MHz) single element plane transducer. Reflectors were aluminum blocks with fine angular adjustments in an optically transparent water tank. The wave reflection and transmission were also studied numerically using finite differences. [Work was supported by RFBR, NIH, and NSBRI grants.]
Fatigue damage evaluation using harmonic generation in polycrystalline copper.
Authors: Reinhardt Brian , Tittmann Bernhard
Published: March 2010

A fundamental goal of ultrasonic nondestructive evaluation is to characterize material defects before failure. During material fatigue, dislocations tend to nucleate and become sources of stress concentrations. Eventually, cracks start to form and lead to material failure. Recent research has indicated that nonlinear harmonic generation can be used to distinguish between materials of high- and low-dislocation densities. This research reports nonlinear harmonic generation measurements to distinguish between those areas of high- and low-dislocation densities in copper bars. The copper bars were subjected to flexural fatigue. Periodic scans were taken in order to track dislocation development during the fatigue life of the material. We show that this technique provides improved early detection for critical components of failure.
Comparison of central masking versus monotic masking in non-simultaneous masking conditions.
Authors: Ahmadi Mahnaz , Feth Lawrence L.
Published: March 2010

The growth of non-simultaneous masking was compared in a central masking versus a monotic masking condition for the same masker and signal parameters. Detection thresholds of normal listeners were measured utilizing a 2AFC up-down adaptive-tracking procedure. Signal-to-masker time intervals were 0, 2, 5, 10, 20, and 50-ms. Brief sinusoidal signals at 0.5, 1, 2, and 4 kHz were masked by a two-octave band of noise of 200 ms duration. The masker was centered on and off the frequency of the signal. Detection thresholds were greater for signal-to-masker intervals less than 50 ms in forward masking using both central and monotic masking conditions. Backward central masking did not result in significant threshold shifts. High-frequency signals produced greater central masking effects; however, signals at lower frequencies were more effectively masked in monotic conditions. In contrast with monotic masking conditions, off-frequency maskers did not produce a clear central masking effect. Results of this study are consistent with neurophysiologic findings of medial olivocochlear bundle response characteristics and support the idea that central masking is mediated by efferent fibers in humans.
Age-related differences in auditory spatial attention depend on task switching complexity.
Authors: Singh Gurjit , Pichora-Fuller M. Kathy , Schneider Bruce A.
Published: March 2010

We investigated the role of simple and complex switching of auditory attention in a multi-talker, multi-spatial listening situation with target location uncertainty. In all conditions, a target sentence from an edited version of the CRM corpus was presented from one spatial location and competing sentences from two different locations, with cues specifying the target’s callsign identity and the probability of its location. Four probability specifications indicated the likelihood of the target being presented at the left, center, and right locations (0-100-0, 10-80-10, 20-60-20, and 33-33-33). In conditions requiring simple switches of attention, the task was to report key words from the target sentence. In conditions requiring complex attention switching, when target callsigns were presented from one of the unlikely locations, the listener’s task was to report key words presented from the other unlikely location. A total of eight younger and eight older adults who had normal audiometric thresholds below 4 kHz participated. The key finding is that, whereas both age groups performed similarly in conditions requiring simple switches of attention, older performed worse than younger listeners in conditions requiring complex switching. Switching complexity may explain, in part, why older adults with relatively good audiograms report difficulty communicating in complex listening situations.
Performance of phonemically targeted processing in conjunction with compression processing with spectral enhancement.
Authors: DiGiovanni Jeffrey J. , Rutledge Janet C. , Umble Chessy S.
Published: March 2010

Sensorineural hearing loss is strongly linked to poorer speech intelligibility, especially in noise. The goal of the present study is to test, individually and in combination, two signal processing strategies designed to improve both consonant and vowel perception. In the first strategy, specific consonants were targeted for processing to increase amplitude and duration. For consonants with a duration increase, the adjacent vowel was decreased proportionately in order to maintain overall word and sentence duration. Second, Col-SE, an adaptive compression processing strategy incorporating spectral enhancement, was used to process stimuli. Hearing-in-noise-test sentences were presented monaurally to normal-hearing and hearing-impaired adults through an insert earphone in the presence of speech-shaped noise. Preliminary results show that normal-hearing listeners benefited from Col-SE processing in conjunction with minimal phonemically targeted speech processing more than with either processing strategy individually. Increases in consonant amplitude and duration beyond a modest amount reduce intelligibility. These data suggest that the two processing strategies are viable to improve speech intelligibility, but that there is a limit to the processing whereby benefits are no longer observed.
Effect of auditory deprivation on binaural sensitivity in bilateral cochlear implant users.
Authors: Litovsky Ruth Y. , Jones Gary L. , VanHoesel Richard
Published: March 2010

Increasing numbers of cochlear implant (CI) users receive Implants in both ears in an effort to restore spatial hearing abilities. A known limitation of commercial CI devices is lack of synchrony to the signal fine timing cues arriving at the two ears. In addition to these hardware limitations, which may contribute in substantial ways to the gap in performance typically seen between bilateral CI users and normal-hearing people, there are considerable inter-subject differences in the type and history of hearing loss. We use a research processor which enables inter-aurally coordinated pulsatile stimulation of selected pairs of electrodes in the right and left ears. This project is concerned with the effects of the age at onset of deafness, and place of stimulation, on binaural sensitivity. Thresholds for discrimination of inter-aural time difference (ITD) and inter-aural level difference(ILD) and pointer-identification for perceived intracranial position were measured. Prelingually deafened subjects had no sensitivity to ITD but retained ILD sensitivity. People with childhood- or adult-onset of deafness retained sensitivity to both ITD and ILD, some within normal-hearing level of performance on some conditions. The role of auditory deprivation in the emergence and preservation of binaural sensitivity will be discussed. [Work supported by NIH-NIDCD.]
Unmanned underwater vehicle self-noise and implications for low-frequency sonar design.
Authors: Houston Brian
Published: March 2010

Sonars configured on small unmanned underwater vehicles tend to be higher-frequency systems that are relatively insensitive to the dominating self-noise associated with low-frequency energy sources. These include the main propulsor, control surface actuators, and navigation components. A new generation of vehicles is required having reduced low-frequency signatures in order to support the growing interest in low-frequency broadband active and passive sonars. In the work presented here, we discuss the impact of vehicle noise on the performance of both real and synthetic receiver arrays. Self-noise mitigation methods and their impact on vehicle architecture will be discussed as well as the use of signal processing techniques employing acoustic holographic projection to reduce the impact of structural-borne noise. [Work supported by ONR.]
Estimation and measurement of the acoustic signature of unmanned surface and underwater vehicles.
Authors: Cuschieri Joseph
Published: March 2010

As the use of unmanned surface and underwater vehicles (USVs and UUVs) increases, the acoustic signature and self-noise of these vehicles become important for certain type of applications. For low-detection probability the UUV or USV must have a low-acoustic signature. Furthermore, the self-noise of the UUV or USV may interfere with on-board sonar sensors, especially as more sophisticated sonar systems are being developed. As the concept of the USV or UUV is to design for low cost and low weight, with low availability of power, it is important to address the mitigation of the acoustic signature during the design phase through estimation techniques based on modeling and component level selection. Additionally during the test and integration phase, methods to measure the acoustic signature without resorting to expensive offshore measurements in “quiet” acoustic test ranges are required. In this presentation some of the approaches available for modeling and testing are discussed, together with the challenges faced by noise control engineers working these type problems and the type of noise sources that have to be addressed.
Measurement and analysis of array gain degradation due to bubble scattering.
Authors: Park J. Daniel , Holt Fred D. , Culver R. Lee , Coles David , Leighton Timothy
Published: March 2010

When an array is steered in the direction of a signal, array gain (AG) is maximum when the signal is coherent across the array, meaning that the signals add in phase for all elements and the noise or interference is incoherent across the array (i.e., it adds with random phase). For an acoustic array operating in the ocean, we would like to understand the degree to which scattering by nearby bubbles degrades AG. Bubble attenuation can also degrade array performance by attenuating the signal of interest, but that is separate from AG degradation. The degradation of AG due to scattering by nearby bubbles has been measured for different bubble densities. We have analyzed the relationship between bubble density at the array and the degradation in AG. We present probability density functions (pdfs) of signal amplitude and phase at the array elements. The amplitude pdfs can be approximated as a Rayleigh–Rice distribution, and the phase pdfs follow the von Mises distribution. With independence assumed between amplitude and phase distributions, simulated distributions generate array gain distributions closely matching the measured AG distribution. [Work sponsored by ONR Undersea Signal Processing.]
A mobile acoustic multiple-input/multiple-ouput communication testbed.
Authors: Song Aijun , Badiey Mohsen , Trembanis Arthur
Published: March 2010

Underwater acoustic data communication is critical for naval and scientific underwater missions. For example, high-rate telemetry between underway autonomous underwater vehicles (AUVs) and surface platforms can facilitate adaptive sampling of the ocean. Multiple-input/multiple-output (MIMO) systems can deliver significant increased channel capacity for underwater communications. At the University of Delaware, an acoustic MIMO communication testbed on a Gavia AUV has been developed for digital communication measurements at the frequency band of 20–30 kHz. The Gavia AUV is a modular, small-size vehicle (20 cm in diameter, 77 kg in air) with a depth rating of 200 m. With advanced navigation systems (INS) and surface communication capabilities (WiFi and Iridium), it has been tested through various coastal-ocean missions. The MIMO system on board is designed for easy, low-cost deployment, and is capable of conducting acoustical sampling via a towed array with or without single-element or multi-element source transmission. In the presentation, the design concept, component detail, and engineering test results will be shown. [Work supported by ONR 321OA.]
Studies of acoustic particle velocity measurements in the ocean.
Authors: D’Spain Gerald
Published: March 2010

This presentation reviews previously published results from applying various signal and array processing methods to the analysis of simultaneous measurements of acoustic particle velocity and acoustic pressure in the ocean. Particular focus is placed on interpreting the properties of the elements of the pressure/particle velocity data cross spectral matrix. These properties are used to evaluate measurements of the deep ocean infrasonic noise field during a period of rapidly changing wind speed. Numerical modeling of the evolution in directionality of the active and reactive acoustic intensity vectors during this time period demonstrates the influence of the continental slope on the flow of underwater acoustic energy. [Work supported by the Office of Naval Research.]
Sensitivity analysis of acoustic channel characteristics to sea surface spectral uncertainty.
Authors: Rosenberg Allan , Zhang Qinqing
Published: March 2010

The interaction of sound with the sea surface is important for underwater acoustic communications. The high-frequency sound used, 10 kHz and above, is sensitive to surface wave frequencies well above the ∼0.5-Hz upper limit routinely measured by wave buoys. Accurately measuring the surface in the short gravity wave regime is difficult and even the general shape of the spectrum is uncertain. The primary measurement challenge is to disentangle the effects of the instrument, including its supporting structure, from what one is attempting to measure. There have been attempts to combine the copious data at low frequencies and the sparse data at higher frequencies to produce model spectra depending on a few parameters that describe the spectrum in the short gravity wave region and above. In this work we study the sensitivity of the acoustic channel characteristics such as the channel impulse response to our uncertain spectral knowledge. We merge low-frequency surface wave spectra measured at NDBC 44014, with various modeled higher-frequency spectra generated from measured environmental parameters to get unified spectra. For each unified spectrum we generate surface realizations, feed them into a rough surface parabolic equation model to compute a channel impulse response, and compare the impulse responses under different surfaces.
Speech privacy in healthcare: A facility director’s and staff.
Authors: Rineer Nikki
Published: March 2010

Hope Within is a healthcare center that has gone the extra mile to have their architecture spaces evaluated for speech privacy. Once identified they have made accommodations to minimize the risk of overheard conversations and have an ongoing program in place to maintain and improve speech privacy performance. Much has been discussed regarding speech privacy in healthcare, but this paper will discuss the point of view from the director and staff.
Measurement of speech privacy of closed rooms using the American Society for Testing and Materials ASTM E2638.
Authors: Gover Bradford N. , Bradley John S.
Published: March 2010

The degree of speech privacy between various locations in buildings has been of increasing concern, driven in part by legislative requirements and the desire for increased security. Until recently, ASTM E1130 “Standard Test Method for Objective Measurement of Speech Privacy in Open Plan Spaces Using Articulation Index” has been the only standardized measurement method available. This test method is, for a variety of reasons, not suitable for assessing speech privacy of closed rooms or conditions of very high-speech privacy. These issues are, however, addressed by the new ASTM E2638 “Standard Test Method for Objective Measurement of the Speech Privacy Provided by a Closed Room.” ASTM E2638 describes a test method suitable for enclosed rooms of nearly all sizes and defines a measure called speech privacy class that can be used to accurately rate speech privacy over a very broad range, from no privacy to very high secrecy. The new E2638 measurement method will be described, and measurements in several real rooms will be presented.
Comparing head rotation angle, visual localization, and recall-proficiency of school-aged children 8–12 while listening to a story by multiple discreet talkers in a virtual classroom.
Authors: Valente Daniel L. , Lewis Dawna E. , Franco John M. , Heinrichs Elizabeth C.
Published: March 2010

In general, children perform more poorly in speech intelligibility tasks than adults while in a noisy environment such as a classroom. This is especially true in discussion situations where the active talkers often are located to the side or behind the student. The purpose of this study was to obtain baseline data for normal hearing (NH) students who experienced multiple-talker stimuli in a controlled virtual classroom environment. Data were gathered using a gyroscopic head-tracker and a post-story comprehension task. Twenty elementary-aged students (ages 8–12, four students per year) were positioned in the center of the classroom and presented a story read by five talkers positioned around the student (reproduced by means of loudspeakers and LCD monitors). Students used different strategies in terms of head rotation over time while performing the experiment and individual differences were seen both across subjects within an age group and between age groups. The post-test comprehension task was used as a metric of performance in the environment. Results from the NH students are compared to a control group of adult NH listeners using head rotation angle over time, comprehension scores, and localization accuracy as salient metrics.
Minke whale boing vocalization density estimation at the Pacific Missile Range Facility, Hawaii.
Authors: Martin Stephen W. , Thomas Len , Marques Tiago A. , Morrissey Ronald P. , Jarvis Susan , DiMarzio Nancy , Mellinger David K.
Published: March 2010

Minke whales (Balaenoptera acutorostrata) seasonally visit the Hawaiian Islands with an apparent peak in activity in the February/March timeframe. Their presence is readily detected acoustically from their boing vocalizations, which are detectable on the Pacific Missile Range Facilities (PMRF) deep-water (3500 m to over 4500-m depth) bottom mounted hydrophones northwest of Kauai, HI. Automated techniques were developed to detect, classify, and associate the boings across 16 separate hydrophones. Over 13 h of data for each of 12 separate days from the 2006 whale season (February/March/April) were processed for detection and classification (D/C) of boing vocalizations. A sample set of the data (10 min from each day) was analyzed to characterize the detection function (probability of detection as a function of horizontal range) and the false positive rate of the boing D/C. Boings were associated across hydrophones, defining a capture history for each boing vocalization. Spatially explicit capture recapture methods were applied to the sample data associations to derive the detection function. Applying the parameters estimated on the sample data set toward the full data ser allows an estimation of the minke whale boing vocalization density in this area over these time periods in 2006.
A modeling tool for therapeutic and imaging ultrasound applications.
Authors: Curra Francesco
Published: March 2010

The fields of therapeutic and imaging ultrasound have broad medical applications. However, the inherent complexity of biological media and the nonlinear nature of ultrasound propagation at therapeutic regimes make optimization and control of the therapy still a challenging task. An accurate modeling tool for solving multi-dimensional ultrasound-based problems in complex geometries that can greatly assist in the optimization and control of the treatment is presented. The model consists of 2-D, 2.5-D (cylindrical symmetry), and 3-D coupled solutions for acoustic and elastic wave propagation in heterogeneous, lossy media complemented by the bioheat transfer equation for temperature estimation. It includes linear and nonlinear wave propagations, arbitrary frequency power law for attenuation, and can account for multiple reflections and backscattered fields. Work is underway for the inclusion of cavitation effects and the extension of the model to adaptive grid refinement and unstructured, deformable grids. Sample results for therapeutic and imaging applications will be presented. [Work supported by US Army MRMC and NIH NIDDK.]
Beamforming for vibro-acoustography using a 1.75D array transducer.
Authors: Urban Matthew W. , Fatemi Mostafa , Alizad Azra
Published: March 2010

Vibro-acoustography is an ultrasound-based imaging modality that maps the acoustic response of an object induced by acoustic radiation force. The method employs two ultrasound beams with frequencies separated by a small difference, typically in the kilohertz range. Using a 1.75D array transducer, which has multiple rows of elements, offers an advantage over linear array transducers because it allows for focusing in the elevation direction. We have performed simulations of different arrangements for the apertures assigned to the two ultrasound frequencies and evaluated resolution and sidelobe levels for different arrangements. However, the large size of the elements produces grating lobes in the transmitted fields. We will describe metrics for evaluating grating lobe levels compared to the main lobe of the transmitted field as a quantitative approach to optimize aperture design. We present experimental measurements of the transmitted field and compare with simulation results. Finally, we present imaging results from phantom experiments. This beamforming study is directed toward improving vibro-acoustography image formation using a General Electric Vivid 7 scanner for breast and thyroid imaging. [Mayo Clinic and two of the authors have potential financial interest related to devices or technology referenced above. Work supported by NIH Grant No. R21CA121579 and AIUM Award No. AIUM-EER#1.]