bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of gray whale calls of San Ignacio Lagoon and their distribution in the water column
Authors: Lpez-Urban Anaid , Thode Aaron , Bazúa-Durán Carmen , Guerra Melania , Urbán-Ramírez Jorge
Published: October 2011

During the winter gray whales congregate in San Ignacio Lagoon, Baja California, in order to breed and give birth. The Lagoon population can be roughly divided into two demographic groups: mothers with calves, and single animals. Here the acoustic behavior of gray whales wintering in the lagoon is studied by using bioacoustics tags to determine potential relationships between call type and call structure, relative calling frequency, and position in the water column among demographic groups. Between 2008 and 2010, 24 tags (Bio-Probe) recording tags were attached to gray whales in San Ignacio Lagoon. From 1591 minutes of recordings, 1250 calls were identified and classified into five call types: conga (S1), quejid, purr, croac, and ronroneo. The last call has not been previously reported for this species. Conga calls were the most common type (88% of calls recorded) and was produced by both demographic groups. Ronroneo calls (5%) were mainly produced by single whales. Differences in call parameters (Call duration, minimum, maximum, and low-maximum frequency, number of pulses, and number of harmonics) were only determined for conga calls, for which statistically significant differences were found between demographic groups. Different call types tend to be produced at different depths.
Scalable distributed ultrasonic microphone array
Authors: Andreassen, Annemarie Surlykke Tórur , Hallam John
Published: October 2011

A modular approach to recording airborne ultrasound will be presented, the solution is based as much as possible, on retail components and open source software. The modular design, where each module has approx. 4 microphones, allows modules to be combined to extend the coverage area or get higher recording resolution. The system has been designed to have no inherent scalability limits, i.e., only limited by data storage available and the number of microphones you can get a hold of. Current implementation has been used for recording in field experiments with bats, both short-term (minutes) on BCI Panama and for long-term recording (months) in Denmark. The generic nature of the design and implementation allows us to easily replace old components with new technology as it becomes available, both hardware and software. This means we reap the benefits achieved by the electronics industry and also gain any software improvements/bugfixes by a simple Internet upgrade of the module software. Modular design introduces some extra complexity, but this is only an issue when real-time processing the data, or with regards to synchronization. Although said complexity also has advantages, one of them being the possibility of parallel processing.
Development of dolphin-speaker
Authors: Mishima Yuka , Uchida Keiichi , Amakasu Kazuo , Miyamoto Yoshinori , Sasakura Toyoki
Published: October 2011

Dolphin speaks broadband sound of ten octave ranges. The vocalization of dolphin sound is categorized into three types, whistle, burst pulse, and echolocation clicks. The frequency range of whistle is below 20 kHz, while that of echolocation clicks and burst pulse is from about several kHz to 150 kHz. Whistle and burst pulse are used social communication. Whistle is used identifying each other and burst pulse may contain emotive factor. Few burst pulse researches are conducted compared to whistle. Until now, burst pulse researches are mainly collecting the dolphin sound using hydrophone but not speaking their sound from human side. The main reason why is no speaking from human side is no speaker of broadband frequency range for burst pulse. The newly developed Dolphin-Speaker has the broadband frequency response from 15 to 150 kHz. The Dolphin-Speaker is developed by advanced technology using multilayer piezoelectric device. We introduce the frequency characteristics of Dolphin-Speaker and the spoken sound by Dolphin-Speaker. We compared the original burst pulse of dolphin and the playback burst pulse by the Dolphin-Speaker. In near future, we would try to playback the burst pulse to dolphin and observe the behavior of the dolphin.
Level repulsion states and cavity modes excited by evanescent waves in sonic crystals waveguides
Authors: Romero García Vicent , Garcia-Raffi Luis Miguel , Vasseur Jérôme , Hladky-Hennion Anne Christine , Sanchez-Prez Juan Vicente
Published: October 2011

The relevance of the evanescent modes in sonic crystals is theoretically and experimentally reported in this work. The complex bands structure, kω, calculated using the extended plane wave expansion reveals the presence of evanescent modes in these systems, never predicted by the traditional usual numerical ω(k⃗) methods. The interpretation of the evanescent modes introduces novel explanations of the deaf bands as well as of the level repulsion states in antisymmetric periodic systems. In this work we observe that in the ranges of frequencies, where a deaf band is traditionally predicted, an evanescent mode with the excitable symmetry appears changing drastically the transmission properties. On the other hand, the simplicity of the sonic crystals in which only the longitudinal polarization can be excited is used here to interpret, without loss of generality, the level repulsion between symmetric and antisymmetric bands in sonic crystals as the presence of an evanescent mode connecting both repelled bands. These evanescent modes explain both the attenuation produced in this range of frequencies and the transfer of symmetry from one band to the other. The experimental evidence of the level repulsion and the evanescent coupling are in very good agreement with the theoretical predictions.
Elastic response of a cylinder containing longitudinal stiffeners
Authors: Hull Andrew J.
Published: October 2011

This talk develops a 3-D analytical model of a cylinder that contains a longitudinal stiffener. The model begins with the equations of motion for a fully elastic solid that produces displacement fields with unknown wave propagation coefficients. These are inserted into stress and displacement equations at the cylinder boundaries and at the location of the stiffener. Orthogonalization of these equations produces an infinite number of indexed algebraic equations that can be truncated and incorporated into a global matrix equation. Solving this equation yields the solution to the wave propagation coefficients and allows the systems' displacements and stresses to be calculated. The model is verified by comparison of the results of a plane strain analysis example to a solution generated using finite element theory. A 3-D example problem is formulated, and the displacement results are illustrated. The inclusion of multiple stiffeners is discussed.
Three approaches to understanding sound radiation from a tuning fork
Authors: Ludwigsen Daniel O. , Russell Daniel A.
Published: October 2011

The simple tuning fork has a remarkable pattern of radiated sound. Measuring and modeling this radiation is the ultimate objective of a module designed for our senior-level laboratory course in acoustics. The primary audience for this course is composed of majors in applied physics and engineering physics, as well as engineering students interested in the acoustics minor, mostly electrical and mechanical engineering majors. To complement the blend of students, the course features a careful mix of theory and analytical modeling, computational modeling, and testing. These approaches run through a series of activities emphasizing practical knowledge, including calibrating microphones, validating a finite element model, measuring sound pressure level to produce polar plots of directivity, and using monopoles, dipoles, and quadrupoles to model and predict behavior of several common sources of sound. With these tools, students examine the sound radiated from a tuning fork driven near its lowest resonance frequency. They collect data to create far field and near field directivity plots and use an intensity probe to map 2-D vector intensity in the plane perpendicular to the tines. These are compared with a quadrupole model, as well as the results of a finite element model of their own creation.
Tablet tools for teaching acoustics
Authors: Faber Benjamin M.
Published: October 2011

Recent advances in tablet computing technology have in some ways made tablet devices, such as the iPad, an attractive and viable alternative to the traditional notebook computer in and out of the classroom. Tablets are not only smaller and lighter than notebook computers, but typically employ capacitive touchscreen technology, which enables an unprecedented level of interactivity between user and device. The media-centric nature of the current crop of mobile devices also makes them potentially useful as teaching aids, both for classroom demonstration as well as for hands-on experimentation. The tablet's utility is further enhanced by wireless and/or mobile Internet connectivity, as well as an increasing amount of available third party software. Potential uses of a tablet computer in teaching acoustics will be discussed.
Using COMSOL multiphysics software to investigate advanced acoustic problems
Authors: Piacsek Andrew A. , Muehleisen Ralph T.
Published: October 2011

Numerical simulations provide a valuable tool for students to investigate complicated behavior found in many applications of acoustics. Computational “experiments” can be conducted quickly for a large number of parameter values, enabling students to visualize abstract quantities and to grasp causal relationships not easily recognized when looking at equations. The COMSOL finite-element multiphysics software package provides an integrated workspace in which the user defines a problem, meshes the geometry, and plots the solution(s). A brief overview of COMSOL will be presented, along with three examples of how it can be used to model advanced acoustics problems often encountered by students. The example problems involve musical acoustics, fluid-loaded shell vibrations, and flow resistance in porous materials. Also discussed will be the educational benefit of examining how choices made setting up the model can affect the integrity of the solution.
Synthesis of harpsichord pluck tones using a physical plectrum and string models
Authors: Perng Chao-Yu J. , Smith Julius O. , Rossing Thomas D.
Published: October 2011

The harpsichord is a plucked string keyboard instrument with a distinct sound, and previous work has been done to synthesize it [V. Valimaki et al., EURASIP J. Appl. Signal. 7, 934–948 (2004)]. However, these excitation signals are extracted through recorded tones and are not physical models in the true sense. A physical model of the harpsichord plectrum and its interface with the digital waveguide string model has been proposed by us [Chao-Yu J. Perng et al., J. Acoust. Soc. Am. 128, 2309(A) (2010)], and a revised model accounting for the plectrum tip was presented subsequently [Chao-Yu J. Perng et al., J. Acoust. Soc. Am. 129, 2543(A), (2011)]. In this paper, we will demonstrate results of the synthesized tones using our physical plectrum-string interaction model. Changing certain physical parameters alters the synthesized tones, and they are discussed and explored. Lastly, a simple physical model of the harpsichord lute-stop is presented.
The sound of quietness. How to design sites that are perceived as quiet?
Authors: Fiebig Andre , Schulte-Fortkamp Brigitte
Published: October 2011

The EC Noise Directive 2002/49, related to the assessment and the management of environmental noise, demands “to preserve environmental noise quality where it is good.” In addition, one major issue of the directive concerns the creation of quiet zones in urban areas. This ambitious goal of creating “acoustically green” and quiet areas in cities cannot be achieved without an interdisciplinary approach, which holistically reflects the human perception of acoustical sceneries. Sound sources constitute a soundscape and semantic attributions to sources become intrinsic properties of the respective acoustic signals. This means that humans cannot distinguish between the physical and the interpreted events. Psychological and social aspects have a sustainable impact on evaluations and must be considered to create quiet areas, which are perceived as quiet and recreative. Thus to understand residents' and visitors' reactions to environmental noise, it is imperative to investigate their expectations and experiences besides considering noise metrics and acoustical indicators. The paper will present outcomes of recent surveys, where quiet areas in Aachen, Berlin, and Leipzig and their impacts on residents and visitors were scrutinized. The analyses have been conducted with special focus on Soundscape design.
Proving a facility complies with noise regulations
Authors: Giglio Mark V.
Published: October 2011

This paper examines the difficulties associated with proving compliance with environmental noise regulations. Topics include determining pre-existing background sound, post-construction measurements during facility operations, and balancing corporate rights with neighborhood expectations. When a new facility is built in a quiet neighborhood, noise complaints are commonplace. The new facility is required to prove compliance with the local noise regulation. Compliance measurements must be made when the facility cannot be shut down and ambient sound levels are unknown. A statistical analysis of the pre-existing background sound often suggests the probability of proving compliance is minimal. In addition, bias toward/against one party in the dispute can have significant ramifications.
A three-dimensional noise mapping study for heterogeneous traffic conditions
Authors: Alur Ramachandraiah , Ramasamy Kalaiselvi
Published: October 2011

Characteristics of noise in terms of frequency, noise level, vary considerably with respect to heterogeneous traffic. Urban traffic noise characteristics in the cities of a like India are slightly varied in the sense that the composition of the traffic is heterogeneous. A heterogeneous traffic stream composes of vehicles having different speeds, sizes, and operating characteristics. While studying the feasibility of noise reduction in some of the areas around a heterogeneous traffic stream, a three-dimensional (3-D) noise mapping study has been attempted with the help of Arc GIS, Arc Scene along with field measurements. The methodology involves to build 3-D noise models to analyze the 3-D occurrence of noise pollution. Specifically in this work a 3-D acoustical model has been developed for a local area. Subsequently, the observation points around the buildings have been determined and the noise levels have been calculated using the authors' regression model. The noise mapping parameters such as Ld, LN, and Lden have been calculated incorporating the geometrical features of the roads and varying heights of the buildings, heterogeneity, and prominent honking conditions. This work leads to the prediction of noise levels in front of building facades both in horizontal and vertical directions.
Experimental and numerical study on the propagation of impulsive sound around buildings and induced structural loading
Authors: Remillieux Marcel C. , Corcoran Joseph M. , Haac T. Ryan , Burdisso Ricardo A. , Svensson U. Peter
Published: October 2011

Propagation of impulsive sound around buildings and induced structural loading are investigated experimentally and numerically. Experiments were conducted on a rectangular building at Virginia Tech using sonic booms generated by an explosive technique. Assuming linear-acoustic propagation and acoustically rigid surfaces, these experiments were simulated with a three-dimensional numerical model, in the context of geometrical acoustics, by combining the image source method for the reflected field (specular reflections) with the Biot-Tolstoy-Medwin method for the diffracted field. This numerical model is validated against a boundary element solution and against experimental data, showing a good overall agreement. Some of the key advantages of this modeling approach for this application are pointed out such as the ability to model three-dimensional domains over a wide frequency range and also to decompose the sound field into direct, reflected, and diffracted components, thus allowing a better understanding of the sound-propagation mechanisms. Finally, this validated numerical model is used to investigate sound propagation around a cluster of six rectangular buildings, for a range of elevated source positions.
Sound transmission modeling for residential buildings using finite elements
Authors: Kim Beom Soo , Sparrow Victor W.
Published: October 2011

Noise transmission into residential building structures has been studied in order to understand the outdoor-to-indoor transmission characteristics. This work is motivated by the need to model the transmission of subsonic aircraft noise into homes. As a first step, finite element (FE) models of a simplified residential house developed using both MSC MD Nastran and FFT Actran were compared to check the validity of the modeling techniques as well as to analyze their applicability for low frequencies. Fluid structure interaction was considered to include the presence of the enclosed acoustic fluid. Model relevance was also checked with impulsive load measured data supplied by NASA in 2007. The FE model of a detailed individual room was developed to show interior pressure responses. [Work supported by FAA.]
Investigation of the sound distribution in street canyons with non-parallel building Façades
Authors: Piippo Kaj Erik , Tang Shiu-keung
Published: October 2011

Sound propagation in street canyons have been a topic of interest for decades. In a congested city such as Hong Kong, street canyons with large height to width ratios are a common sight. Many prediction models have been developed over the years, but the problem is still of interest because of the complexity due to the multiple reflections and varying surface conditions in real life cases. In this paper, a 1:4 scale model experiment of a street canyon, 4 m long and 2 m high, is presented where one of the facades is inclined. The reference case is with two parallel facades, which is compared with cases when one facade is tilted 80°, 70°, and 60°. The measurements were conducted in an anechoic chamber and a line source array generating white noise was used for simulating traffic noise. The sound distribution patterns were studied on the reference wall and the inclined wall. It was observed that the sound strength and the reverberation decrease rapidly when inclining the opposite wall. For low and mid frequencies, the sound reduction was more significant closer to the top of the inclined facade, while the opposite could be seen for the vertical facade.
Resonant ultrasound techniques for measurements from 500 mK to 700 K
Authors: Betts Jonathan B. , Migliori Albert , Shehter Arkady , Fanelli Victor R. , Balakirev Fedor F.
Published: October 2011

Measuring elastic moduli using resonant ultrasound spectroscopy (RUS) over a very wide temperature range requires very specialized hardware. The authors have developed both this hardware and some interesting software to help make measurements in these very challenging conditions. Solutions to these problems will be presented, along with results from some recent RUS experiments carried out at the National High Magnetic Field Laboratory in Los Alamos. [Work was supported by the National Science Foundation, State of Florida, and the U.S. Dept. of Energy.]
Resonant ultrasound spectroscopy at high temperatures and pressures: Palladium hydride near the tri-critical point
Authors: Gladden Joseph R. , Adebisi Rasheed
Published: October 2011

Much fundamental quantum and critical phenomenon physics has been learned from precision elastic constant and attenuation measurements at low temperatures. Less attention has been paid to phenomenon in the high temperature regime outside of specialized areas such as geophysics. However, interesting fundamental and applied physics does not stop at room temperature. In this talk, I will review methods developed for applying resonant ultrasound spectroscopy at high temperature (<1300 K) and high hydrostatic pressure (<140 atm). One of the phenomenon we have studied using this apparatus is palladium hydride near the tri-critical point in the temperature, pressure phase diagram. The results from these measurements have validated a recent theory by Schwarz and Khachaturyan (2006) regarding the hysteresis in metal hydride systems which predicts a strong softening in the elastic moduli.
Phonon-driven electron localization in delta-plutonium
Authors: Migliori Albert
Published: October 2011

Three remarkable properties of delta-Pu, accurately measured, lead to exceptionally strong constraints on ab-initio electronic structure models and suggest a new route must be taken to understand the localization of electronic states. The three properties that lead to this are the thermal expansion coefficient, the temperature dependence of the elastic moduli, and the absolute values of the elastic moduli. Both neutron diffraction and dilatometer measurements of the thermal expansion reveal a broad temperature range where thermal expansion is zero, and where small changes in Ga concentration can make thermal expansion vary from small and positive to small and negative. Measurements of the bulk modulus of these alloys over the same temperature range reveal extreme softening on warming. How can the bulk modulus, which is the curvature of the energy with respect to volume, change when volume does not? This is the central property that is not encompassed by present electronic structure models. We discuss theory and RUS measurements to understand better what must be true.
Acoustics of metals under extreme conditions by laser-ultrasonics in diamond anvils cell
Authors: Decremps Frédéric , Belliard Laurent , Perrin Bernard , Gauthier Michel
Published: October 2011

Major progress on ultrafast acoustics instrumentation and diamond anvils design during the last 2 yr now allows detailed elastic and visco-elastic studies under extreme conditions and on a wide variety of systems. I will here mainly review the state of the art of the recent development of a method combining the time-resolved picosecond optical technique and a diamond anvil cell to measure sound velocity Decremps et al., [Phys. Rev. Lett. 100, 3550 (2008)]; Decremps et al., [Rev. Sci. Instrum. 80, 73902 (2009)]. Contrary to other groups which currently scope with these problems mostly using large facilities, we propose here entirely new and novel technique to measure the sound velocity of solid and liquid under high pressure and high temperatures. I will illustrate these possibilities by a number of recent studies on crystalline, polycrystalline, and liquid metals. Prospects will be discussed.
Acoustic levitator for contactless transport and mixing of droplets in air
Authors: Bjelobrk Nada , Nabavi Majid , Poulikakos Dimos
Published: October 2011

Acoustic levitation is a simple and cost-effective method for investigation of small amounts of any kind of material. Standard levitators focus the standing acoustic wave only along its traveling direction. Therefore, levitated objects (entrapped in the potential minima) are separated by potential maxima which cannot be overcome. Thorough design of the emitter plate and consequently its vibration pattern allows a more complex acoustic field between the emitter and reflector, establishing multiple potential minima perpendicular to the wave propagation direction in the H1-mode. The number of minima is regulated by changing the emitter-reflector distance H. Thus, multiple solid or liquid samples can be simultaneously levitated and rapidly transported over several centimeters by controlling H. A piezoelectrically driven droplet generator was used to eject pL droplets into the acoustic field and coalesce them to a 1–2 μL sized droplet in the preferred potential minimum. Two suspended droplets were transported and mixed when two potential minima were merged into one by increasing H. During pattern transition, high pressure fluctuation might increase droplet Bond number beyond its critical value and cause droplet atomization. This was prevented by continuous adjustment of acoustic power.
Effects of heat conduction in wall on thermoacoustic wave propagation in a gas-filled, channel subject to temperature gradient
Authors: Sugimoto Nobumasa , Hyodo Hiroaki
Published: October 2011

This paper examines effects of heat conduction on acoustic wave propagation in a gas-filled, channel subject to temperature gradient axially and extending infinitely. Within the narrow-tube approximation in the sense that a typical axial length is much longer than a channel width, the system of linearized equations for the gas supplemented by the equation for heat conduction in the solid wall is reduced to a thermoacoustic-wave equation for excess pressure uniform over the cross-section. This is the one-dimensional equation taking account of the wall friction and the heat flux at the wall surfaces given in the form of hereditary integrals. This equation is derived rigorously under the narrow-tube approximation, and is valid for any form of disturbances. The effects of heat conduction appear in the form proportional to the square root of the product of the ratio of the heat capacity per volume of the gas to that of the solid, and the ratio of the thermal conductivity of the gas to that of the solid. Although the product is very small usually, which endorses validity in neglect of the heat conduction, it is revealed that there are situations in which its effects are enhanced, depending on geometry and materials.
Correlation processing of ocean noise
Authors: Kuperman W.A.
Published: October 2011

Correlation processing of ocean ambient noise has been a topic of growing interest. While theory confirms the efficacy of this procedure, experimental confirmation has been limited to a few data sets. The basic issue of the potential utility of this procedure is the time needed to build up the relevant cross-correlation peaks that are diagnostic of the ocean environment. This time is a function of frequency/bandwidth, the ocean environment and noise structure/distribution, sensor separation and, if employed, the array configuration. After reviewing some basic background, a selection of experimental results for noise originating from ships, surface generated sources, and geophysical sources is presented.
Analyzing structure-borne sound by using the forced vibro-acoustic components
Authors: Natarajan Logesh Kumar , Wu Sean F.
Published: October 2011

At the 158th meeting of the ASA, a numerical study on analyzing structure-borne sound radiation using the forced vibro-acoustic components (F-VACs) established by the Helmholtz equation least squares (HELS) method was presented [Natarajan et al., JASA, 126, 2244 (2009)]. The present paper presents an experimental case study of this approach on a baffled square plate subjected to a point force excitation using random signals. The radiated acoustic pressures are measured by a planar array of microphones at a very close distance to the plate surface. These input data are used to determine the F-VACs of the plate obtained by decomposing the transfer functions into orthogonal space via singular value decomposition. These F-VACs are correlated to sound radiation through sound power calculations. Meanwhile, the F-VACs are expanded in terms of the natural modes of the plate, so the dominant F-VACs that are directly responsible for sound radiation can be correlated to the natural modes of the plate. Using this F-VAC analysis, one can identify the critical natural modes of a structure, which by themselves have no direct relationships to sound radiation. Based on the F-VAC analysis results, the plate is modified and tested to examine its effectiveness in reducing structure-borne radiation.
An improved method of structural-borne random vibration mass attenuation
Authors: Majed Arya , Henkel Ed , Kolaini Ali
Published: October 2011

In 2009, the NASA Engineering and Safety Center (NESC) Vibroacoustics Working Group identified vibroacoustic environment predictions as one of the highest risk areas for new launch vehicle programs. Specifically, the working group identified the need for improved random vibration mass attenuation prediction methods as key to mitigating this risk. This paper derives a multi drive point, multi axis, interface sized equation between the unloaded and loaded drive point random vibration accelerations and cross correlations. The method's development and associated acoustic test validation program were a collaborative effort between ASD, NESC, and NASA/JPL. The derivation utilizes the methods of modal synthesis and random vibration averaging and precludes the use of any simplifying structural interaction assumptions besides the interfaces behaving linearly (no interface deadbands). Key to the method's improved accuracy is its built-in mechanism for combining the contributions of the different unloaded drive-point accelerations and associated cross-correlations. The method reduces to the time-tested method of Norton–Thevenin for the single drive-point case. Predictions are compared to measurements from NASA/JPL acoustic chamber test of a panel loaded by a component. It is shown that the method accurately captures the major spectral characteristics of attenuations and amplifications resulting in improved mass loaded environment predictions.
The perception of phonetic features and acoustic cues by impaired listeners
Authors: Winn Matthew B. , Chatterjee Monita , Idsardi William J.
Published: October 2011

The search for invariant acoustic cues in the perception of speech features has been an under-utilized blessing to those interested in individuals with hearing impairment. While multiple co-varying acoustic cues complicate the search for invariance, they provide plentiful opportunity for impaired listeners to perceive contrasts that would otherwise be lost when salient information is compromised by hearing loss or noise. Classic confusion matrices and information transfer analyses account for phonetic features perceived, but do not always reveal the acoustic cues that drive these perceptions; it is rarely acknowledged that difficult listening conditions that are likely to result in a re-prioritization of acoustic cues. In this presentation, we discuss some completed and ongoing work suggesting that impaired listeners (or simulated impaired listeners) don't merely show different amounts of success but exhibit different listening strategies (i.e., cue-weighting strategies) when perceiving phonetic features. This is similar to findings related to developing language learners and adult learners of a second language. Implications are discussed here for cochlear implant users, listeners with high-frequency hearing loss, and listeners in background noise in tasks that measure the use of cues in both the auditory and visual domains.
Individual variance of hearing-impaired consonant perception
Authors: Han Woojae , Allen Jont
Published: October 2011

Individuals with sensorineural hearing loss (SNHL) are prescribed hearing aids (HAs), based on the results of clinical measurements. Although the HAs do help these individuals communicate in quiet surroundings, many listeners have complained that their HAs do not provide enough benefit to facilitate understanding of normal speech. We argue that the current clinical measurements, which interpret the result as a mean score (e.g., pure-tone average, speech recognition threshold, AI-gram, etc.), do not deliver sufficient information about the characteristics of a SNHL listener's impairment when hearing speech, resulting in a poorly fitting HA. We confirm how reliably this consonant-vowel (CV) test could measure a SNHL listener's consonant loss using only zero-error utterances (in normal hearing listeners) and having a statistically suitable number of presentations in CVs, in order to characterize unique SNHL consonant loss. As noise increased, the percentage of error and confusions of target consonants increased. Although some consonants showed significantly higher errors and resulted in more confusion than others, SNHL ears have a very different consonant perception/error, which may not be either measured or analyzed by the use of average scores. Comparison between the two (separated) phases of the study supports a good internal consistency for all SNHL ears.
Deriving invariance by integrating cues computed relative to expectations
Authors: Jongman Allard , McMurray Bob
Published: October 2011

Invariance and variability are notions that have stimulated much research on the acoustics and perception of speech. While some invariance must exist to explain how listeners generally derive the same message from spoken input, the question remains at which level invariance occurs. The theory of acoustic invariance explicitly states that the invariance is found in the acoustic signal. While some phonemic distinctions do seem to be represented by invariant acoustic properties, it is clear that many acoustic cues are context-dependent. Normalization or compensation processes for coping with specific sources of variability have been proposed as solutions to this context-dependency. We examined acoustic properties for a large corpus of American English fricatives. We argue that the lack of invariance is not a major obstacle and demonstrate that it can be overcome by the use of multiple acoustic cues and a relatively simple compensation scheme by which cues are recoded relative to expectations derived from context (vowel quality and speaker). A comparison of this approach (C-CuRE, Computing Cues Relative to Expectations) [McMurray and Jongman, Psych. Rev. 118, 219–246 (2011)] to acoustic invariance and exemplar approaches suggests that only C-CuRE achieved a similar accuracy to listeners and showed the same effects of context.
Perceptual recovery of phonetic features in blanked segments of disyllabic words
Authors: Divenyi Pierre L. , Lammert Adam C.
Published: October 2011

Spondees, both true disyllabic words and concatenated monosyllabic word pairs, had their middle section replaced by silence that extended from the midpoint of the first to the midpoint of the second vowel; the silence thus included the final consonant(s) of the first and the initial consonant(s) of the second syllable. These stimuli were presented to normal-hearing young listeners instructed to guess both monosyllabic half words. Input and response spondees were orthographically aligned and analyzed as confusion matrices. Articulatory gestures were estimated for each token via the Haskins Laboratories TADA articulatory synthesis. After time alignment, articulatory distances were calculated for each stimulus-response pair. In the blanked middle of the spondee, phoneme-based confusions of place-of-articulation were high (39% accuracy), while gestural distances underlying this feature (location and degree of tongue tip constriction, lip aperture, and velar constriction) were under 10%. These results suggest that acoustic traces of a significant portion of gesture trajectories underlying consonantal place-of-articulation that start before and/or terminate after the silence, are perceived by the listener. An articulatory phonology might thus be more robust to degradation. [Work supported by NSF, AFOSR, and the VA Medical Research.]
Effectiveness of sparse optimization techniques against rapid fluctuations in the shallow water acoustic channel
Authors: Sen Gupta Ananya , Preisig James
Published: October 2011

The shallow water acoustic channel exhibits rapid temporal fluctuations due to fluid and platform motion as well as reflection from moving surfaces. Tracking the time-varying channel delay spread effectively for subsequent equalization is an open signal processing challenge. The delay-Doppler spread function characterizes this time-variability over a selected range of Doppler frequencies but itself does not exhibit stationary behavior over longer time intervals. Typically the delay-Doppler spread function and sometimes the delay spread itself follow a sparse distribution where most of the energy is concentrated in a few significant components distributed sparsely over a larger support. A variety of sparse optimization techniques have recently been proposed in the compressive sensing literature to efficiently track sparsely distributed coefficients. However, the ill-conditioned nature of the delay-Doppler spread estimation problem, coupled with the necessity to track the complex-valued coefficients directly in real time, renders direct application of traditional sparse sensing techniques infeasible and intractable in the shallow water acoustic paradigm. The talk will provide a synopsis of well-known and recently proposed sparse optimization techniques, with focus on mixed norm algorithms, along with a comparative analysis of these techniques in the shallow water acoustic paradigm over simulated and experimental field data.
Modeling dominant mode rejection beamformer notch depth using random matrix theory
Authors: Buck John R. , Wage Kathleen E.
Published: October 2011

Any practical tracking algorithm must mitigate the effect of both nonstationary environments and loud interfering sources. The dominant mode rejection (DMR) adaptive beamformer (ABF) is often used to address these challenges. The DMR beamformer periodically updates the sample covariance matrix (SCM) employed to compute the ABF weights. A tension arises between the large number of snapshots required for each SCM update to null loud interferers effectively and the small number of snapshots required for each SCM update to track nonstationarities. In practice, observed notch depths for DMR fall dramatically short of those predicted theoretically from ensemble statistics. This talk bridges the gap between theoretical and observed performance by presenting a simple linear asymptotic model for the DMR notch depth derived from random matrix theory results on the accuracy of the SCM eigenvectors. The model predicts the mean DMR notch depth as a function of the number of snapshots given the interferer-to-noise ratio (INR), the array size, and the interferer location relative to the look direction. Close agreement is demonstrated between the model and simulations over a wide range of INRs and array sizes. [Work supported by ONR 321US.]
Underwater target tracking using the waveguide invariance
Authors: Zurk Lisa M.
Published: October 2011

Target tracking in underwater environments is complicated by false alarms introduced from scattering from the sea bottom and sea-air interface, as well as returns from biologics in the water column. It is difficult to devise a method to discriminate the false alarms from targets of interest because their nature is highly dependent on the environmental conditions, which are often poorly known. A topic of recent interest in active sonar is the application of the waveguide invariant to improve target discrimination and tracking. The invariant relationship gives a robust (i.e., not environmentally dependent) method of relating the time-evolving frequency content to attributes of the target. In this talk, the concept of target discrimination and tracking using the waveguide invariant is discussed in the context of other environmentally robust techniques. Results are presented for fixed and towed array systems.
Milestones in naval through-the-sensor environmental acoustic measurements
Authors: Barlett Martin , Brown Walter E. , Clements Joe M.
Published: October 2011

This paper describes recent developments in the Bottom Loss and Scattering Strength Measurement System (BLOSSMS). The objectives of the BLOSSMS project are to (1) create technology from which measurements of several types of active sonar scattering phenomena may be made using a single unifying measurement and analysis scheme, (2) integrate measurements from Fleet active sonar systems with seafloor bathymetry and modeled acoustic data into a single root database, (3) develop algorithms that are based on sound physics and oceanographic principles to identify salient information in the root database for analysis, and (4) produce acoustic scattering parameters that are useful in sonar system performance analysis and the optimization of sonar operations. In this paper, the methods used to measure bottom backscatter strength, bottom forward scatter (bottom loss), and volume scatter strength are discussed. Examples of the resulting scattering parameters are provided. Also discussed are the advantages, disadvantages, and challenges that are associated with this approach to measuring fundamental acoustic scattering phenomena.
Comparative analysis of mid-frequency bottom loss derived from two distinct measurement paradigms
Authors: Barlett Martin , Brown Walter E. , Harris Carolyn , Siderius Martin
Published: October 2011

This paper describes a comparison of acoustic mid-frequency bottom loss data derived from two distinctly different measurement methods, systems, and platforms. One data set was derived from measurements made by a passive drifting line array. The second data set was derived from measurements made from a Navy destroyer equipped with an AN/SQS-53C active sonar system that utilizes a hull-mounted volumetric cylindrical array. Data were collected off the west coast of the United States. Detailed comparisons and analysis of the derived co-located bottom loss data were made. The metric used for comparison was the difference of the estimated MGS curves at specific co-located sites. The set of MGS curves used as the metric for comparison between the two methods ranges from MGS-1, corresponding to a low-loss bottom, to MGS-9, corresponding to a high-loss bottom, in one tenth increments, i.e., MGS-1.1, MGS-1.2, to MGS-8.9, MGS-9.0. The results from the two methods were found to be in excellent agreement.
Analysis of through-the-sensor observed and modeled reverberation using sensor derived scattering parameters
Authors: Barlett Martin , Brown Walter E. , Keenan Ruth E.
Published: October 2011

Recent developments in the bottom loss and scattering strength measurement system (BLOSSMS) program support the use of on-scene measurement of acoustic scattering parameters important to the performance of mid-frequency sonar systems. These parameters could include bottom and volume scatter strength (backscatter), and bottom loss. In this paper, examples of BLOSSMS-derived bottom loss and backscatter estimates for data collected off the west coast of United States are used to compute reverberation levels for select locations and bearings. Included in the discussion are analysis of the oceanographic conditions and relevant bathymetric features.
Implications of the presence of shell hash on the speed and attenuation of sound in water-saturated granular sediments
Authors: Argo Theodore F. , Wilson Preston S.
Published: October 2011

The propagation of sound through water-saturated granular sediments has been widely studied, yet there is no consensus on an expected wave speed and attenuation in these materials owing to variation in both physical properties and test methods used for their interrogation. One aspect confounding model predictions is the presence of inhomogeneities such as rocks, bubbles, and biological organisms in an otherwise homogeneous sediment. In a laboratory setting, it is possible to control both manufacture of artificial sediments with specific inclusions and the measurement method used to observe their properties. To study the effect of inclusions on the speed of sound and attenuation in an otherwise homogeneous sediment, shells were systematically added to a sand sediment. The volume fraction of shells relative to sand grains was varied and the speed of sound and attenuation was measured using a time of flight technique from 200 to 800 kHz. Results will be compared to both sediment acoustic models and scattering models.
Pragmatic model-based adaptation for optimal acoustic communication and sensing on autonomous marine vehicles
Authors: Schneider Toby E. , Schmidt Henrik
Published: October 2011

Autonomous underwater vehicles can be valuable acoustic sensing platforms due to their maneuverability, low cost, and sensor-driven adaptivity compared to ships. However, the logistics of integrating acoustics research into artificially intelligent systems can be daunting. In this work, the autonomy software provides an abstract representation of the acoustic environment (e.g., sea surface, water column, and sea floor parameters, source and receiver positions) which it updates continuously from local and remote sensor data. Upon request, this environment is translated into the native representation of an acoustic model which returns the requested calculation (e.g., transmission loss, travel times). The model is set up as a server, capable of handling requests from multiple autonomy subsystems at once (e.g., target tracking prediction, acoustic communications optimization). Thus, the acoustic model and the autonomy software are kept ignorant of each other's implementation specifics. Results will be presented from the shallow water GLINT10 experiment where a vehicle adaptively tracked in depth the minimum modeled transmission loss from a buoy source. Furthermore, a deep sea simulation study which combines target tracking and acoustic communications was conducted. For both studies, the autonomy software MOOS-IvP and the BELLHOP ray tracing codes were used.
Deployment of wideband bio-inspired sonars for autonomous underwater operations
Authors: Lane David M. , Capus Chris , Brown Keith , Pailhas Yan
Published: October 2011

Recent developments in the understanding and application of wideband bio-inspired acoustic sensors are enabling new applications of autonomous underwater vehicles (AUVs) for security and oilfield use. Appropriate use of wideband signals has enabled improved discrimination between natural and man-made objects that have physically similar appearance, as well as the detection of buried and partially buried objects. Wideband sonar developments in the Ocean Systems Laboratory at Heriot-Watt University have focused on prototypes based on the bottlenose dolphin sonar, covering a frequency band from around 30 to 150 kHz and having a frequency dependent beam-width that is, considerably larger than conventional imaging sonars. In parallel, AUV technology has developed to allow much greater levels of autonomy in allowable vehicle behavior. New generations of vehicle have moved beyond switching of pre-programmed scripts (behaviors) and their parameters, to systems that interleave planning and execution at a fine grain, or can re-plan mission sections on the fly in response to unexpected events. Combining this improved sensor performance with increased autonomy has enabled a first generation of fielded system to act responsively in tasks such as tracking and inspection of proud or buried cables, and the detection and characterization of mines, beyond being mine like objects. Second generation systems that use their autonomy to optimally take multiple looks and control the spectral content of pings in an environmentally adaptable way are under consideration.