bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental courses of infants' articulations estimated by acoustic-to-articulatory inversions
Authors: Oohashi Hiroki , Watanabe Hama , Taga Gentaro
Published: October 2011

Knowledge about the actual movements of articulators and their developmental changes in early childhood is crucial to a better understanding of the relationship between speech productions and perceptions. In this study, we attempted to recover the shapes of articulators from the acoustic properties of infants' vocalizations by using a variable linear articulatory model (Boe, 1999). We randomly selected 30 samples of 5 Japanese vowels at three age groups (8, 24, and 50 months) from the NTT Japanese infants speech database (Amano etal., 2002) and those pronounced by adults. We modeled shapes of articulators and size of the vocal tract according to Maeda (1990) and synthesized vowels by forward transformation from the vocal tract cross-sectional area function to its acoustics. We performed inverse estimations of articulatory parameters from acoustic properties by using a pseudo-inverse of the Jacobian matrix. Statistical analysis of the estimated articulatory parameters revealed that the shapes of articulators during vowel pronunciations became closer to those of adults over developmental courses. Developmental courses of some articulators represent the u-shaped curve (e.g., tongue shape and tongue tip of /a/) and those of others represent the linear curve (e.g., tongue position of /o/).
An international standard for the measurement of vessel underwater noise
Authors: Bahtiarian Michael
Published: October 2011

The development of a new international commercial standard for “Underwater Noise Measurement of Ships” started in April 2011. This effort follows on an American National Standard, ANSI/Atomic Security Agency (ASA) S12.64-2009/Part 1, Quantities and Procedures for Description and Measurement of Underwater Sound from Ships, Part 1; General Requirements. Currently, no international standards exist for performing underwater noise measurements of ships. For many years, the field of underwater noise from ships has been the exclusive specialty of the Navy. However, non-navy vessels are looking to be just as quiet so that they can perform better science. Green ships are being conceived in order to have less emission into the ocean. The goal of the project is to develop an International Organization for Standardization (ISO) standard for the measurement of underwater noise levels of ships using commercial technology. One aim is that the standard would be applicable to any open ocean site in the world and not require traveling to special acoustic test ranges. The committee' scope of work will include neither regulatory actions nor the development of any underwater noise level but will address both deep and shallow water sites. This presentation provides an update of the committee work to date and outreach to the acoustical community.
An approach to computing acoustic wave propagation in shallow water
Authors: Clark Cathy Ann
Published: October 2011

A shallow water mode solution is presented, which approximates the water column sound speed variation using isovelocity layers. Within a layer, two fundamental solutions are seen to satisfy the separated depth-dependent wave equation and complex analogs apply in evanescent regions. Solutions which satisfy an upper boundary condition are extended continuously through isovelocity layers to the bottom, matching functions and derivatives at layer boundaries. The value of the Wronskian for the Green's function thus obtained is used to locate the eigenvalues of the normal modes comprising the propagating field. Acoustic mechanisms which are dominant in shallow water such as forward scattering and range dependence are incorporated as matrix multiplications to implement horizontal coupling between modes. Agreement between the shallow water approach and a benchmark deep water mode solution is shown for a number of shallow environments.
Acoustic modes in a curved internal wave duct
Authors: Lin Ying-Tsong , McMahon Kara G. , Siegmann William L. , Lynch James F.
Published: October 2011

Observations and numerical simulations have shown that nonlinear internal waves in continental shelf and shelfbreak regions can form 3-D acoustic ducts. The strength of ducting depends on the size of internal waves, the width of the gap between waves and the curvature of the wave front, and also on the acoustic frequency and the vertical mode number. It has been seen in numerical simulations and simplified ray theory that for a given internal wave structure and a given frequency, higher vertical modes are easier being trapped in a curved internal wave duct. Also, the number of the lowest mode trapped between curved waves increases as the frequency goes up. In this talk, a 3-D normal mode theory is employed to analyze these observed characteristics. The analysis is carried out in a cylindrical coordinates, and two types of horizontal modes are found: whispering-gallery modes and full bouncing modes. Both types of modes can be described by Bessel functions, and the asymptotic formulas can be used in some limiting cases. [Work supported by the ONR.]
Getting it together—Interdisciplinary sound environment research
Authors: Mossberg Frans
Published: October 2011

The Sound Environment Center at Lund university is an interdisciplinary center created to coordinate research on sound and soundscape issues and is known to be the first of its kind worldwide. Ranging from acoustics to medicine, psychology, and cognitive sciences, as well as humanities like musicology and linguistics, soundscape research adresses many interdependent areas and touches upon health as well as philosophical, aesthetic, and technical issues. To get a holistic comprehension, these perspectives need to be synchronized. Therefore, the center has an interdisciplinary board and a mission to study sound environments from multidisciplinary perspectives. Focus lies on research and contact between researchers. The center has external funding for larger research collaborations on topics such as teachers voice strain and rooms acoustics, health effects of combined exposure to noise and airborne particles, cognition, and sound exposure. In addition to initiating research projects, the center arranges symposiums adressing topics such as Noise and health, Seductive Sounds, Operational Sounds, Dangerous Sounds' and Sound, Cognition and Learning. Further topics have been Sound Design, Sounds and Silence for Mental Recreation, Teachers Voice Comfort, and recently Wind Turbine Noise. The symposiums facilitates cross disciplinary contacts and discussions, many of them producing published papers and reports.
On the soundscape of urban parks
Authors: Bento Coelho J. Luis , Boubezari Mohammed
Published: October 2011

Urban parks are parts of every city fabric and usually well appreciated by the citizens for providing restoration and some “quiet,” at least when compared to most other city areas. Research on the soundscape of parks in cities in Portugal and in Brazil have been conducted in order to assess what makes such areas sonically interesting. Work is being directed to the differentiation of the sound components of the overall sound environment in different types of parks and on techniques for mapping the perceived sound components. The work also aims at understanding effects of climate and culture on the perception of the soundscape. Results are presented and discussed.
Urban sound design—Utopia or urgent need
Authors: Hllgren Nina
Published: October 2011

Today we are facing the consequences of about 100 years of urbanization, confronting questions about quality of life in relation to efficiency and economical benefits. Hard facts are considered to be more reliable than values which are not so easily measurable. The quality of sound is one of them. Urban designers and architects are currently not fully aware of the interaction between the built outcomes of their work and the process of propagation and perception of sound. Designing houses, relations between houses, connections between places, whole neighborhoods, and cities is a serious task affecting many different aspects of life. But we can still note a recurring absence of knowledge regarding the complex relation between visual and sonic realities. This reality is in fact what surrounds the urban inhabitant for an entire lifetime. But what can or should the architects and planners do? As has been recently pointed out in a report on the subject, this professional group is lacking the tools, language, and guiding examples for being able to implement anything in reality. Implementing what? What can really be done or designed to improve the sonic environment and for what purpose?
Piazza del Marchese Paolo: An architectural and soundscape design to redevelop an outdoor public space
Authors: Sberna Achille , Asdrubali Francesco , Schulte-Fortkamp Brigitte
Published: October 2011

This paper will report about a design procedure regarding the redevelopment of an open square located in the historical center of Città di Castello, Italy. The square has five entrances and it is surrounded by old buildings. The Public Library of the town is also located at this place. Currently, the square is used as a parking lot. The goal of the design is to redevelop this square matching the given context. For the design procedure, first, the visual and acoustical status of the place will be described. Second, binaural recordings will be carried out to measure the acoustical climate and third, soundwalks will be conducted to help to detect the soundmarks of the area. Moreover, the idea is to transform the space in a pedestrian area and to consider the square as an acoustical “outdoor floor” for the library. The design process will be focused on the preservation of the genuine Soundscape.
Researching sound in silence
Authors: De Blonde Jurgen
Published: October 2011

Aifoon is an educational arts organization that investigates sound in silence. We investigate poetic and communicative possibilities of everyday sounds. Our aim is to have people communicate about their immediate surroundings in a non-verbal way by using sounds taken from those surroundings. In our workshops, we teach people to record sounds, we teach microphone awareness, we open ears, draw sounds, and compose with these drawing, compose with sound, make a montage on a computer, and talk about the results. We avoid using music and words since these two elements are too coded. We take the results and the questions that rise from our work back to artists, researchers, and the public for further interpretation and investigation. We have taken our core philosophy as a basis for an exposition, a number of events, an ensemble, and a couple of installations in an attempt to take our educational role beyond the workshop session into the public space. This has proven successful and has often helped us to explain our ideas and outsiders to understand them.
2006 International Music Festival
Authors: Dugger Edward
Published: October 2011

Throughout the 3-week run of the 2006 International Music Festival held in Boca Raton, Florida, the 4000 seat Mizner Park Amphitheatre was fitted with an active acoustic system. We will present a case study that explores many of the elements of the project including the initial audio system selection, installation, rehearsals, and performances. Since this was an unusual project both in its exterior application and large scale, we will present the design features that had significant implications for the musicians, concert presenters, stage hands, and audience. At the request of the venue operators, a new design has been developed to install a permanent active acoustic system for the amphitheater. This design will also be presented.
Eavesdropping on coconut rhinoceros beetles, red palm weevils, Asian longhorned beetles, and other invasive travelers
Authors: Mankin Richard W
Published: October 2011

As global trade increases, invasive insects inflict increasing economic damage to agriculture and urban landscapes in the United States yearly, despite a sophisticated array of interception methods and quarantine programs designed to exclude their entry. Insects that are hidden inside soil, wood, or stored products are difficult to detect visually but often can be identified acoustically because they produce 3–30-ms, 200–5 000-Hz impulses that are temporally grouped or patterned together in short bursts. Detection and analysis of these sound bursts enables scouts or inspectors to determine that insects are present and sometimes to identify the presence of a particular target species. Here is discussed some of the most successful acoustic methods that have been developed to detect and monitor hidden insect infestations. Acoustic instruments are currently available for use in rapid surveys and for long-term monitoring of infestations. They have been useful particularly for detection of termites, coconut rhinoceros beetles, red palm weevils and Asian longhorned beetles in wood, white grubs and Diaprepes root weevil in soil, and stored product insects.
Vascular permeability with targeted contrast agents—The effect of physiologically relevant dynamic shear stress
Authors: Anastasiadis Pavlos , Rychak Joshua J. , Allen John S.
Published: October 2011

Targeted ultrasound contrast agents (UCAs) may be able to facilitate an early noninvasive diagnosis of atherogenesis. The coronary arterial branches might be routinely scanned for a clinical diagnosis since plaques often first form at disturbed flow regions within bifurcations. However, many outstanding questions exist on the targeting efficacy subject to pulsatile and potentially pathological flow in these areas. Targeted ultrasound contrast agents conjugated to the antibody of the intercellular adhesion molecule-1 (ICAM-1) are injected into y-shaped flow chambers that model the coronary heart artery bifurcations. Simultaneous measurements of the barrier function in physiologically relevant dynamic shear stresses are monitored with electric cell impedance (ECIS) measurements. The study aims at quantifying variations of the barrier function at regions with exposure to different shear stresses and correlating this information to the binding efficacy of targeted UCAs conjugated to the antibody of ICAM-1. These results are discussed with respect to reported targeted ultrasound contrast agent studies of inflammation and plaque in Apolipoprotein E-deficient mice.
Inhibition of breast cancer cell proliferation by low-intensity pulsed ultrasound (LIPUS)
Authors: Katiyar Amit , Sarkar Kausik , Sarker Krishna
Published: October 2011

Cancer is the second leading cause of death in the United States, preceded only by heart disease. Cancer cells display an uncontrolled proliferation, controlling which has been a big challenge for cancer treatment. Ultrasound is best known for its application in diagnostic imaging; it is also a vehicle for delivering high frequency mechanical stimulation toward beneficial bio-effects. Unlike high intensity focused ultrasound, which is recently being investigated for thermal ablation of solid tumors, low intensity pulsed ultrasound (LIPUS) is directed toward cellular mechanisms. The effects of LIPUS on cancer cell proliferation are not known. Here, we demonstrate that LIPUS dose-dependently inhibits proliferation of breast cancer cell T47D as determined by several biochemical assays such as MTS, Alamar Blue, and BrdU assay. Statistically significant inhibition of T47D cell proliferation is observed when cells are exposed to 50–100 mW/cm2. For this intensity range, LIPUS excitation inhibits the proliferation of T47D cells upto 50%. We also notice that inhibition of cell proliferation by LIPUS depends on its exposure time on cells. Minimum exposure time of LIPUS excitation for pronounced inhibitory effects on T47D cell proliferation is approximately 10 min.
Artificial flesh material selection for hearing protection evaluation system
Authors: Bicak Mehmet M. A. , Oliver Josiah M. , Shank Kevin R.
Published: October 2011

Developing an advanced hearing protection evaluation system (HPES) in the form of an acoustic test fixture (ATF) allows for characterizing either circumaural or insert-type hearing protection devices (HPDs) in both impulse and continuous noise environments across the dynamic range of human hearing. This is a challenging task since the acoustical transfer paths through flesh contribute to the dynamic response of the system. Current ATFs do not account for the transfer paths through flesh to ear canal. In this study, we investigated several visco-elastic flesh materials numerically using coupled vibro-acoustic simulations, and experimentally using vibration and acoustic excitation methods. Geometrically representative prototypes are being developed using volume computed tomography (VCT) that include detailed features of the skull and flesh structure, so that flesh conducted sound transmission paths can be physically modeled. The HPD on ATF dynamic behavior is compared with the HPD on subject behavior using finite element simulation models developed using the VCT images. The material selection is validated using noise reduction and vibration experiments on the subjects.
Vector wave measurements on landmine detection with an array of loudspeakers focused on the ground
Authors: Barlett Martin L. , Gorhum Justin D. , Wright Wayne M. , Hamilton Mark F. , Muir Thomas G.
Published: October 2011

An array of 16 loudspeakers, deployed along a segment of the base of a right circular cone, was used to focus sound on soils overlying buried targets lying along the conical axis of the source. Measurements were made at several incident angles tending toward grazing to examine long range detection for humanitarian de-mining applications. Targets and soils were instrumented with triaxial geophone and accelerometer sensors. The transmission of airborne sound into the soils produced vertical and radial vibrations in both the soil and the targets, which included rigid and compliant mine cases. Several waveform transmission types were utilized. The compliant targets provided resonances amenable to optical detection, depending on the acoustic, geometric and environmental parameters, which are discussed. [Work supported by the IRD program at ARL:UT Austin, in cooperation with the National Center for Physical Acoustics.]
Measurements of the ground acoustic environments for small solid rocket motor firings
Authors: Vu Bruce T. , Plotkin Kenneth J.
Published: October 2011

During the ground launch of a space vehicle, the mobile launcher deck and tower are exposed to severe acoustic environments. These environments, if not properly managed, can weaken ground support equipment and result in structure failure. The ground acoustic environments are different than the vehicle acoustic environments. They are typically more severe because of the close proximity of the rocket plume, which often involves direct impingement. They are more difficult to predict, and their measurement and data reduction remain challenging. This paper discusses these challenges and describes the methods of processing ground acoustic data during a series of static firings of a 5-percent scale solid rocket launch vehicle and mobile launcher, known as the Ares Scale Model Acoustic Test.
On the jet-wake similarity
Authors: George Ballard W.
Published: October 2011

This paper is concerned with similarities and differences between jets and wakes, as indicated by a sampling of the literature, including what tests and studies have been made in each case. As noted by Franken, jets and wakes are both characterized by a region of shear and (depending on the Reynolds number) high turbulence. Jet noise has been extensively studied under the impetus of a strong concern with community noise. Jet noise studies have examined numerous quantities including, for example, spectra, directivity, source location, and total power. Lighthill published widely quoted papers on sound generated aerodynamically, primarily in the context of jet noise and without solid boundaries. Literature referred to for this paper was primarily for airborne sound and included underwater sound, in which case cavitation plays a significant role and tends to mask turbulent wake noise due to the vehicle body. Propellers are a source of wake as well as lift noise. A readily noticeable difference between jets and wakes involves the fact that jets can be tested statically, while for wakes there has to be relative motion. Also jets, though not jet engines, can be tested “cold.”
Statistical estimation of speech kinematics from real-time MRI data
Authors: Lammert Adam , Ramanarayanan Vikram , Goldstein Louis , Iskarous Khalil , Saltzman Elliot , Nam Hosung , Narayanan Shrikanth
Published: October 2011

The human speech production system can be fundamentally characterized by the kinematic relationships between low-level articulator variables and relatively high-level tasks. Such kinematics can be illuminating about many system aspects from degrees of freedom and redundancy to dynamics and even control. Since these relationships are generally complex and infeasible to express in closed form, recent work has focused on statistical methods for estimating the relevant relationships from data (Saltzman, 2006, in Dynamics of Speech Production and Perception; Lammert, 2010, Proc. INTERSPEECH). Such methods have been applied to synthetic speech data in order to evaluate their effectiveness, but they have not yet been demonstrated on real data. Here, we apply these methods to real speech data acquired from real-time magnetic resonance imaging. We extract articulator variables that are consistent with those chosen by various articulatory models, and we relate them to high-level task variables such as constriction locations and degrees and formant frequencies. This is done to facilitate an analysis of articulatory motor control during speech production. [Work supported by NIH.]
Semi-automatic modeling of tongue surfaces using volumetric structural MRI
Authors: Bone Daniel K. , Proctor Michael I. , Kim Yoon , Narayanan Shrikanth S.
Published: October 2011

Although volumetric magnetic resonance imaging has proven to be a valuable tool in the study of consonant production (Narayanan etal., 1995; Kröger etal., 2000), its utility is limited by the difficulty and laboriousness of reliably extracting tissue boundaries from imaging data. Current methods typically involve manual segmentation of air-tissue boundaries (e.g., Birkholz, 2006). Conventional automated (Atkins, 1998) and semi-automated (Ashton etal., 1995) methods used for the segmentation of brain MRI datasets may not be directly applicable to lingual segmentation because they are designed to work with different anatomical features. We present a method for extracting tongue surfaces from hi-resolution volumetric MRI data with limited user intervention. For each vocal tract volume to be analyzed, a lingual bounding box and search seed was first specified by an expert user, and voxel intensity was normalized across the region of interest. Lingual surfaces were automatically identified using a multi-pass region-growing algorithm operating over coronal planes. Thresholding was performed asymmetrically to allow for differential detection of air, teeth, and palatal boundaries, in opposition to adjacent lingual tissue. Smoothed tongue surfaces were fit to the resulting volumes by incorporating prior knowledge of intrinsic lingual musculature. [Work supported by NIH.]
Diphthong centralization and reduction in constriction degree
Authors: Hsieh Fang-Ying , Goldstein Louis , Iskarous Khalil
Published: October 2011

Diphthongs in Mexian Hakka Chinese have been divided into two categories (Cheung 2007): Endpoints of the falling (in vowel space) diphthongs have formant values equivalent to those of the monophthongal vowels, while the endpoints of the rising diphthongs generally have more centralized formants. This categorization provides a chance to test the hypothesis of Iskarous etal. (2010) that in speech production the location of constriction (CL) changes discretely in transitions between successive targets, while the degree of constriction (CD) changes continuously. We therefore hypothesize that the centralization in these diphthongs results from a reduction in CD (possibly due to undershoot) rather than CL, thus making it parallel to common consonant reduction changes in languages, such as spirantization of stops. The current study tests this hypothesis using TADA (TAsk-Dynamic) modeling, in which CD and CL in speech production can be manipulated. Diphthongs [ia], [ua], [ai], and [au] were modeled, and the preliminary results indicate that a change in target CD alone yields formant patterns that are more similar to those reported compared with a change in CL. Results of additional studies will be presented that analytically derive CD and CL in these diphthongs from new data collected from speakers of Hakka.
Suprasegmental features in Northern Paiute
Authors: Brooks Joseph D.
Published: October 2011

The relationship between intonation and word-level stress in Northern Paiute (Western Numic; Uto-Aztecan) is described in order to support the level of phonology as a basis for the lexical, syntactic, and ideational integration of connected speech into intonation units (IUs). Word-level stress in Northern Paiute, intrinsic and in most cases peninitially fixed, is manifested by vowel lengthening and a rise in pitch. Intonation depends largely on the word-level pitch rises, minimalizing the frequency range for non-tonic accents and increasing it for most rising tonic accents of most IUs. The opposite pattern also occurs, whereby non-stressed syllables of individual words have an intonation pattern superimposed upon them; most tonic accents with falling pitch and a few with rising pitch over a non-stressed syllable distinguish this second category as independent from word-level stress. Although these two patterns can explain how suprasegmental features integrate words into larger, cohesive units, the deictic word class is an exception. Deictics in Northern Paiute lack intrinsic pitch, have extra-long vowels, and occur overwhelmingly in IU-final position. It is proposed that suprasegmental features serve as a cohesive force between the areas of linguistic structure by varying degrees of phonological integration.
Pragmatically determined variation in Greek wh-question intonation
Authors: Gryllia Stella , Baltazani Mary , Arvaniti Amalia
Published: October 2011

This paper presents production data testing the analysis of Arvaniti and Baltazani (2005) and Arvaniti and Ladd (2005) according to which the default melody used with Greek wh-questions is L*+H L- !H% (showing a delayed accentual peak on the utterance-initial wh-word, a low stretch, and a final curtailed rise), with !H% sometimes being replaced by L%. Here it was hypothesized that the melodies also differ in pitch accent and are used in different contexts. Four speakers, two male and two female, took part in reading a varied corpus of questions in contexts that lead to the use of a wh-question either in order to seek information or in order to politely register disagreement (a function of wh-questions peculiar to Greek). Our results confirmed that there are two different melodies: L*+H L- !H%, with a delayed accentual peak and a final rise, and L+H* L- L%, with an early peak and no final rise. The former is used for requesting information and the latter when questions function as dissenting statements. In addition to leading to a revision of the existing analysis, these results show that distinctions such as statement versus question are too coarse-grained for the analysis of intonational meaning and function.
Prosodic characterization of reading styles using audio book corpora
Authors: Proctor Michael I , Katsamanis Athanasios
Published: October 2011

Although native English speakers have strong intuitions about the felicity of different reading styles, it is unclear which properties of read speech contribute to these reactions. Although the prosodic structures of read speech and spontaneous speech have been shown to differ (Howell and Kadi-Hanifi, 1991; Blaauw, 1994), it is not clear whether similar prosodic factors contribute to the perception of different reading styles as more felicitous nor even whether such differences can be systematically quantified. A large-scale corpus analysis of read speech was conducted to shed more light on the prosodic characteristics of those reading styles preferred and dispreferred by native speakers of American English. Audio book recordings of classic works of English literature by male and female American readers were rated by native speakers. The two most and least preferred renditions were transcribed at lexical and phonemic levels using SailAlign (Katsamanis, 2011). A variety of metrics were calculated to characterize prosodic properties of each of the readers, including %V, VarCoV, VarCoC, and nPVI (Grabe, & Low 2002; Stojanovic, 2009). The results suggest that although listeners exhibit a preference for syllabic regularity, the perceived felicity of reading styles results from a combination of factors. [Work supported by NIH].
Bistatic scattering by scaled solid metallic objects: Circular line-scan measurements and modeling
Authors: La Follett Jon R. , Malvoso Patrick C. , Lim Raymond
Published: October 2011

Multistatic sonar systems can be used to obtain target scattering information that cannot be measured monostatically. This information has potential benefits for detection and classification schemes. Bistatic and monostatic scattering measurements have been performed simultaneously on several scaled targets using the circular line-scan system of the small scale test bed facility at NSWC PCD. Water tank measurements were made for targets in the free-field and resting proud on or buried in simulated scaled sediment composed of spherical glass beads. Targets were placed in the center of the circular scan line. Circular synthetic aperture sonar and frequency-aspect target strength (acoustic color) results will be presented for a solid steel sphere, solid aluminum cone, and solid aluminum cylinders. Results for cylinders and the sphere are compared with T-matrix simulations to facilitate interpretation of features observed. Comparisons between back and forward scattering results demonstrate particularly strong features for each target in the forward scattering direction. Forward scattering by the sphere and cylinders also exhibits responses that arrive earlier in time than sound that travels directly from the source to the receiver. In the case of the sphere, this is attributed to elastic target responses involving leaky Rayleigh waves. [Research supported by ONR.]
Affects of nearby bubbles on underwater array gain
Authors: Culver R. Lee , Park J. Daniel
Published: October 2011

Combining multiple sensor signals coherently (i.e., beamforming) improves spatial or angular resolution and increases signal to noise ratio (SNR). When the array is steered, signals arriving from the steering direction add in phase, while signals arriving from other directions do not (proper choice of signal frequency assumed). Array gain (AG) is a measure of how much the SNR at the array output is increased relative to array input SNR. The degradation in underwater acoustic array AG by scattering from nearby bubbles was measured at the AB Wood tank located at the Institute of Sound and Vibration Research (ISVR), University of Southampton, in June 2008. AG degradation is separate from the effects of bubbles in water to attenuate acoustic signals. Measured statistics of signal phase at the individual sensors show that as bubble density increases, phase differences between the elements increase and AG is degraded. We present a theory and numerical simulation that attributes the phase shifts to scattering from nearby bubbles and provides a way to predict AG degradation from the bubble density. Work sponsored by ONR Undersea Signal Processing.
Transport equations for cross-frequency transport equations for acoustic intensity moments
Authors: Creamer Dennis B.
Published: October 2011

The second and fourth moment mode-amplitude statistics for ocean sound propagation through random sound-speed perturbations are investigated using exact transport theory for the cross-frequency cross-mode coherence matrix. These exact equations are derived using the method of successive approximations, originally developed by Klyatskin and Tartarskii. These equations allow the determination of the validity of the usual transport equation (involving the Markov approximation), which is the first order approximation (in a infinite sequence of approximations to the exact equations). The range scales for the approach to the asymptotic behavior of the intensity moments, and the decay of the cross-modal coherence is easily determined at all frequencies.
Variations in the active and reactive intensity components of the sound field due to nonlinear internal waves
Authors: Barton Robert J. , Dossot Georges A. , Smith Kevin B.
Published: October 2011

Shallow water acoustic energy propagation influenced by nonlinear internal waves is investigated by examining complex acoustic intensity vector fields. The acoustic field is modeled using the three-dimensional Cartesian version of the Monterey-Miami parabolic equation (MMPE) algorithm, which relies upon a split-step Fourier approach. The modeled internal wave is approximated using environmental mooring data from the Shallow Water '06 (SW06) field experiment, interpolated into a representative three-dimensional sound speed profile, and incorporated into the PE model. The soliton wavecrests are oriented such that they are parallel to the direction of forward acoustic propagation and variations along their length (such as curvature) are neglected. Both pressure and particle velocity fields are computed in a self-consistent manner, allowing a full description of the three-dimensional acoustic intensity field which describes the flow of energy in the presence of the solitons. The complex intensity field is separated into its active and reactive (real and imaginary) and spatial components and presented in the form of energy plots. Specific modeled examples showing horizontal refraction, focusing, and defocusing effects on the structure of the acoustic intensity field are illustrated.
Passive acoustic monitoring of vessel presence at Rose Atoll and the National Park of American Samoa
Authors: Fisher-Pool Pollyanna , Lammers Marc O. , Munger Lisa M. , Wong Kevin , Brainard Russell E.
Published: October 2011

American Samoa is in the process of evaluating the development of a network of marine protected areas (MPAs) to preserve coral reef environments and to prevent the decline of fish populations. Two long-standing MPAs in American Samoa are Rose Atoll Marine National Monument (RAMNM) and coastal marine regions within the National Park of American Samoa (NPSA) system. NPSA includes areas on the populated island of Tutuila, while RAMNM is approximately 130 miles away from the nearest population. Both are protected marine reserves where commercial and public recreational fishing are restricted, although the size and remoteness of the locations create a challenging task for observation and enforcement. A growing management concern over the decline of large fishes and possible illegal fishing has prompted interest in vessel incidence within the two MPAs. We gathered evidence of vessel presence with the use of long-term, autonomous passive acoustic monitoring within the two MPAs. Here we present results of vessel detection within acoustic recordings collected 2009–2010 at RAMNM and 2006–2007 and 2008–2009 at the NPSA Tutuila location. Results from this study highlight the patterns and seasonality of vessel incidence and provide managers with information to assist enforcement.
A high-fidelity model for mitigating underwater pile driving noise in a shallow ocean waveguide
Authors: Cockrell Kevin L. , Stokes Ann , Davis Dwight
Published: October 2011

Driving large piles into the seafloor, as is done when constructing off-shore wind farms, produces high level underwater noise that can have an adverse effect on local marine life. This talk reviews an investigation of methods to mitigate this pile driving noise. A numerical model was used to simulate the structural vibrations in the pile and its coupling to the acoustic field in surrounding air, water and sediment. The simulated acoustic field in the immediate vicinity of the pile was then coupled into an ocean waveguide propagation model using a virtual-source technique to match the boundary conditions. These numerical models were used to assess the relative contribution of the air-borne, water-borne, and sediment-borne acoustic radiation to the noise level in the water-column at ranges up to several hundred meters from the pile. Various noise mitigation methods were simulated and compared. It was determined that a dewatered cofferdam, which places a layer of air between the vibrating pile and the seawater, has the potential to reduce the far-field noise level by approximately 20 dB. A practical method for creating a dewatered cofferdam during construction is the subject of ongoing work.
Underwater structure-borne noise analysis using a finite element/boundary element coupled approach
Authors: Lee Dooho , Kim Hyun-Sil , Kim Bong-Ki , Lee Seong-Hyun
Published: October 2011

Radiated noise analysis from ship structure is a challenging topic due to difficulties in accurate calculation of fluid-structure interaction as well as massive degree of freedoms of the problem even in the case of finite element/boundary element coupled formulations. To reduce the severity of the problem, a new added mass and damping approach is proposed in this paper. The complex frequency-dependent added mass and damping matrices are calculated by using the high-order Burton-Miller boundary element formulation in order to obtain accurate values over all frequency bands. The calculated fluid-structure interaction effects are added to the structural matrix calculated by commercial finite element software, MSC/NASTRAN. An iterative solver is introduced to solve the eigenvalue problem because the combined system matrices are complex and frequency-dependent. The calculated eigenfrequencies for a submerged cylindrical shell show good agreement on reference data. The accuracy and efficiency of the present formulation is compared with those from conventional finite element/boundary element formulation. The comparison results show that the present formulation has better accuracy than the conventional one because of accurate added mass and damping calculation.
Hearing threshold measurements using auditory evoked potentials of four stranded short-finned pilot whales (Globicephala macrorhynchus) in Key Largo, FL
Authors: Greenhow Danielle R. , Brodsky Micah , Lingenfelser Robert , Mann David A.
Published: October 2011

Approximately 26 short-finned pilot whales, Globicephala macrorhynchus, stranded in Cudjoe Key, FL, on May 5, 2011. Four animals, two adult and two juvenile females, were transported to a rehabilitation facility in Tarpon Basin, FL. Auditory evoked potentials (AEPs) were recorded in response to amplitude modulated tone pips modulated at 1000 Hz. AEP thresholds were determined at 10, 20, 40, 80, and 120 kHz for all the four animals. Audiograms were similar to previous findings in pilot whale hearing tests. Short-finned pilot whales have a lower peak sensitivity than other odontocetes such as bottlenose dolphins. Greatest sensitivity was 40 kHz for all whales, while thresholds for the two adults were 25–61 dB higher at 80 kHz than those for the juveniles tested. Click evoked potentials were similar between the four whales and comparable to other echolocating odontocetes. Five total pilot whales have been tested during two separate stranding events; the previously tested juvenile male was found to have profound hearing loss (Mann et al., 2010; Schlundt et al., 2011). These findings add to the limited database of pilot whale (short- and long-finned) hearing studies, of which there are only two others (Schlundt et al., 2011; Pacini et al., 2010).
Migrating gray whale vocalizations and concurrent visual observations near Santa Barbara, California
Authors: Roche Lauren K. , Smith Michael H. , Širović Ana , Cope Allison M. , Buccowich Jasmine S. , Wiggins Sean M. , Hildebrand John A.
Published: October 2011

The vocalizations of migrating eastern North Pacific gray whales (Eschrichtius robustus) are not well understood, but studying these sounds may provide insights to their behaviors and encounters along their migratory route. To record migratory gray whale sounds over long periods, a high frequency acoustic recording package (HARP) was deployed from March to May 2010 off the north coast of the Santa Barbara Channel, an area where the gray whale northbound migration is close to shore. The HARP recorded continuously and concurrently with a shore-based visual survey of marine mammals. Comparisons of calls and sightings were conducted to relate calling repertoires with various types of migrating whale behaviors and groups (e.g., cow/calf pairs, juveniles, etc.). The spatial and temporal overlap of the visual and acoustic data enabled the estimation of call detection ranges and source levels. Characterization of gray whale vocalizations also will help with the development of automatic detectors which will aid in future the investigations of long-term gray whale recordings, including potential responses to anthropogenic activity.
Characterization of dynamic baffles in biosonar and biomimetic devices
Authors: Meymand Sajjad Z. , Pannala Mittu , Müller Rolf
Published: October 2011

The pinna shapes of horseshoe bats are actively actuated to undergo non-rigid deformations on a time scale of one tenth of a second. These cycle times are similar to the durations of the echoes that the animals receive. Hence, it is possible that the bat pinnae are undergoing a change in shape while an individual echo is impinging on them. Such a dynamic reception paradigm based on a continuously deforming baffle are an interesting concept for explaining the biosonar as well as the design of bioinspired devices. Beampatterns are the standard characterization of time-invariant reception devices. In a beampattern, device gain is given as a function of direction and frequency. The Fourier transform that underlies this representation does not represent time variant behavior. Hence, new ways to characterize the time-variant behavior of a deforming baffle have to be found. This is further complicated because a complete description of system behavior requires four independent variables: azimuth, elevation, and either two time variables or time and frequency. Representations that are either time-frequency or entirely time based and use different ways to visualize the overall system behavior have been implemented and tested on the responses of biomimetic pinna shapes.
Similarity spectra and the effect of propagation on F-22 spectra at afterburner
Authors: Neilsen Tracianne B. , Gee Kent L.
Published: October 2011

The afterburner spectra of a static F-22 Raptor have been compared to the similarity spectra from the two-source theory for jet noise. In the two-source theory, fine-scale turbulent structure (FSS) account for sideline radiation and large-scale structures (LSS) dominate the radiation for inlet angles aft of 125 deg for model-scale jets [Tam and Zaman, AIAA J. 38(4), 592–599 (2000)]. A comparison of the similarity spectra with F-22 afterburner data, recorded at ground-based microphones along the 40-ft foul line, shows good agreement between the FSS spectrum and the sideline radiation and the LSS spectrum and the spectrum measured at 150 deg. However, discrepancies exist between the measured spectrum in the direction of maximum radiation and the LSS spectrum. Most significantly, the high frequency roll-off in the data is shallower (approx. 20 dB/decade) than predicted by the LSS (29.8 dB/decade). Most likely this difference comes from nonlinear propagation of the noise, which could then cause the agreement with the similarity spectra to be dependent on distance. Results from the ongoing investigation into how the measured spectra evolve relative to the FSS and LSS spectra as the noise propagates are presented. [Work sponsored by the Air Force Research Laboratory.]
Shock associated noise generation in curved turbulent Coanda wall jets
Authors: Lubert Caroline
Published: October 2011

Curved three-dimensional turbulent Coanda wall jets are present in a multitude of natural and engineering applications. The mechanism by which they form a shock-cell structure is poorly understood, as is the accompanying shock-associated noise (SAN) generation. This paper will discuss these phenomena from both a modeling and experimental perspective. The Method of Characteristics will be used to rewrite the governing hyperbolic partial differential equations as ordinary differential equations, which will then be solved numerically using the Euler predictor-corrector method. The effect of complicating factors such as radial expansion and streamline curvature on the shock-cell location predictions will be discussed. Comparison of the theoretical calculations of the shock wave structure with associated schlieren flow visualization results will be presented. Related acoustical measurements will also be communicated. In this way, critical flow characteristics for shock-cell formation will be identified, and their influence on SAN discussed.
A two-dimensional model for control of centrifugal fan inlet noise in a notebook computer
Authors: Boyle John K. , Esplin J. James , Sommerfeldt Scott D. , Gee Kent L.
Published: October 2011

Previous work on active control of exhaust noise from small centrifugal fans demonstrated significant reductions of the blade passage frequency (BPF) tone. A fan and heat-sink were placed within a mock-up notebook computer case, and control of the fan exhaust noise was measured. It was found that control of the BPF in the exhaust did not significantly affect noise radiated from the fan inlets into the notebook casing, suggesting that exhaust noise and inlet noise may be controlled separately without one adversely affecting the other. In the current work, a two dimensional half-space, source coupling model has been developed to calculate the field within the notebook casing caused by the inlet noise. As a first approximation, free-space boundary conditions were used. A two-dimensional space was constructed to test the model, and error sensor placement was predicted. Measurements of radiated sound power show significant reduction of the blade passage frequency tone. Factors influencing experimental agreement with the model are discussed, such as modal effects and primary source location.
Compliant-wall methods for fluid-borne noise reduction
Authors: Marek Kenneth A. , Earnhart Nicholas E. , Cunefare Kenneth A.
Published: October 2011

One means of addressing fluid-borne noise in hydraulic systems is to add a compliant-walled section to the flow path. The impedance mismatch at the section boundary reflects a substantial amount of acoustic energy back to the source, and additional damping may be present due to the compliant material. While hoses can be used to add this compliance, the hose wall vibration produces undesirable breakout noise from the system. Additionally, the requirement that the hoses contain system pressure determines the minimum practical hose stiffness. An alternative approach is to use a silencer composed of a rigid outer housing, an internal compliant liner, and a central flow path through the liner. Such a configuration would avoid the pressure bearing and breakout noise complications while still adding compliance to the system. These two approaches are compared in this study, with simulated transmission loss presented for various lengths and material properties of the compliant sections.