bluuebunny/crossref_metadata_2025 huggingface dataset:
Studying articulatory variability using functional data analysis
Authors: Lucero Jorge C. , Lofqvist Anders
Published: October 2013

This paper examines articulatory variability across repetitions using functional data analysis. In this analysis, signals are time-normalized using a smooth function of time. The magnitude of the time-warping function provides an index of phasing (temporal) variability; a separate index of amplitude variability is calculated from the time-normalized signal. Here, lip, jaw, and tongue movements in vowel–consonant–vowel sequences recorded using a magnetometer were used for the analysis. Preliminary results suggest articulator specific patterns of variability. Thus vertical jaw movements showed small amplitude variability for alveolar consonants, like /s, t/. As expected, the amplitude variability of the tongue tip was small during alveolar consonants, where the tip is in contact with the alveolar ridge. However, the amplitude of the tongue tip movement varied considerably at the release of alveolar stops. The horizontal and vertical movements of the same articulator often showed a different amount of amplitude variability. For example, during the movement from the first to the second vowel in /api/, the tongue body showed small vertical and large horizontal variability. The results will be discussed in terms of articulatory, acoustic, and perceptual constraints on speech production. [Work supported by CNPq, Brazil, and NIH.]
Effects of upright and supine orientation on tongue position during silence
Authors: Stone Maureen , Sutton Martin , Parthasarathy Vijay , Prince Jerry , Li Min , Kambhamettu Chandra
Published: October 2013

Previous work has examined the effects of supine orientation on tongue position during speech using ultrasound image sequences [Stone et al., J. Acoust. Soc. Am. 111, 2476(A) (2002)]. That work compares upright and supine ultrasound image sequences during repetition of words. Results indicate backward tongue rotation during supine position, plus several phonemic effects. The present project extends that work by examining silences between the words. The work is of interest because MRI data are collected in supine position. Use of that data to develop models and support theories of speech production calls for an understanding of the differences between supine and upright tongue orientation. Cine-MRI is collected by repeating a short word at timed intervals, such as one second. The word lasts for about half the second followed by silence. During the speech, the effects of gravity on tongue behavior are coupled with the speech demands. During the silence, there are fewer constraints on tongue behavior. The tongue is anterior and reflects neighboring phonemes and small periodic inhalations. Thus, the tongue may resist the gravitational pull to keep the airway patent and facilitate inhalation. This study will compare multiple subjects and words regarding tongue location, mobility, and variability in upright and supine orientation.
Control of closure duration in labial stop consonants
Authors: Lofqvist Anders
Published: October 2013

This paper examines lip and jaw kinematics in the production of labial stop consonants where the duration of the oral closure is varied for linguistic purposes. The subjects were speakers of Japanese and Swedish, two languages that have a contrast between short and long consonants. Lip and jaw movements were recorded using a magnetometer system. Based on earlier work showing that the lips are moving at a high velocity at the oral closure, it was hypothesized that speakers could control closure duration by varying the position of a virtual target for the lower lip. According to this hypothesis, the peak vertical position of the lower lip during the oral closure should be higher for the long than for the short stops. This would result in the lips staying in contact for a longer period. Results from five subjects suggest that this is the case for those who produce nonoverlapping distributions of closure duration for the two categories. However, the peak velocity of the lower lip raising movement did not always differ between the two categories, suggesting that differences in muscle activation duration rather than virtual target position is another potential control variable. [Work supported by the NIH.]
The vocal-tract ‘‘potential function:’’ Many-to-one mappings and compensatory articulations in speech production
Authors: Forbes Barbara J.
Published: October 2013

A fully quantitative, mathematical framework for the analysis of compensatory articulations is described. It is shown that the physics of speech production is best described by a spatial ‘‘potential function,’’ which, unlike cylindrical n-tube approximations, accounts for dispersive wave phenomena in regions of rapidly varying cross section. It is demonstrated that many possible area functions, and hence articulatory configurations, correspond to a single potential function, and so it is claimed that the potential-function descriptor is a both more accurate and more compact basis for the scientific investigation of phonetic systems. This work demonstrates that a 27-vowel system may be simulated from just 8 binary, potential-function parameters. The acoustic correlates of the individual ‘‘bits’’ are discussed, and it is found that they characterize the main vowel classes in a transparent way. Transformations from high to mid, and from mid to low, vowels are obtained, along with those involving the tense–lax and round–unround dimensions. It is shown that vocal-tract area functions familiar from the literature can be deterministically recovered from the 8-bit strings, although many others are also possible. It is claimed that the potential-function vocal-tract model has uniquely abstract and compact properties, and is suitable for development as a full phonological representation.
Microanalysis of perturbation-induced temporal changes in repetitive and discrete utterances
Authors: Saltzman Elliot , Lofqvist Anders
Published: October 2013

In earlier work, we used phase-resetting techniques in which mechanical perturbations are delivered to the articulators during repetitive speech utterances (/...pepepe.../), and analyzed the resultant temporal changes in order to assess the manner in which the peripheral articulators are coupled to ‘‘clocklike’’ processes in the central nervous system. We found that the perturbations induced systematic steady-state shifts in the timing between successive bilabial opening gestures for /p/, demonstrating a resetting of a central clock for these utterances. These results were limited to analyzing durational changes in the opening–closing bilabial ‘‘cycle’’ periods (defined between the onsets of successive bilabial opening gestures). However, in work on perturbed discrete utterances, we also found that most of the perturbation-induced durational changes (shortening) occurred during the lip opening phase of the opening–closing bilabial period, while the closing phase was relatively resistant to temporal distortion. We have therefore conducted a more fine-grained set of analyses on the repetitive utterances of our phase-resetting data to localize the parts of the opening–closing gestural cycle in which shortening occurs, and to compare these detailed repetitive kinematics with those obtained in the perturbed discrete utterances. Preliminary results indicate that the repetitive and discrete utterances behave similarly. [Work supported by NIH.]
Frequency and sentence position in the production of word-final /d/ in North-Central Peninsular Spanish
Authors: Gonzalez Carolina
Published: October 2013

In Spanish, /b, d, g/ are usually pronounced as voiced approximants. In North-Central Peninsular Spanish, these speech sounds are frequently fricated and devoiced. Previous research on this dialect using nonce words showed that word-final /b, d, g/ are fricated more often in stressed syllables than in unstressed syllables [Gonzalez (2001, 2002)]. This study investigates whether other factors are responsible for frication and/or voicing of these sounds. Specifically, the role of frequency and sentence position is examined in the pronunciation of word-final /d/ in real words. Eight speakers of this dialect read a word list with 15 common words like verdad (truth) and 15 rare words like efod (ephod), both in sentence medial and sentence final position. The word list included eight tokens for each word and position, and it was randomized for each speaker and repetition. The effects of frequency and word position will be discussed, and the results will be contrasted with previous research. [Work supported by Del Amo and the Basque Government.] (To be presented in Spanish.)
Coarticulatory fundamental frequency effects associated with Ju/hoansi guttural consonants
Authors: Miller-Ockhuizen Amanda
Published: October 2013

This study presents the results of an investigation of the fundamental frequency of vowels following guttural clicks in Ju/hoansi. Ju/hoansi contains an extremely rich set of consonantal phonation types that behave as gutturals, having contrastive aspirated, uvularized, epiglottalized, and glottalized clicks. Additionally, closure voicing is contrastive for oral aspirated, nasal aspirated, uvularized, and epiglottalized consonants, making the language a good test case for the effect of voicing on fundamental frequency of the following vowel. Fundamental frequency traces were created from the inverse of glottal period durations, which were calculated between adjacent Epoch marks (point of maximum glottal closure) determined by the ESPS Epochs utility associated with XWAVES. This methodology avoided pitch halving and doubling that is often found following nonmodal consonant phonation types. Previous studies have shown lower F0 following voiced unaspirated and voiced aspirated consonants, which have led to the expectation that voicing is associated with lowering of fundamental frequency. The results here show that voicing only lowers fundamental frequency when the release phase of a consonant is voiced as is the case for the voiced aspirated clicks, and not when there is only closure voicing, as is found in the case of the voiced epiglottalized clicks.
Assessing the time course of learning new acoustic–motor relationships using a frequency-altered feedback paradigm
Authors: Jones Jeffery A.
Published: October 2013

Speakers rely on a learned mapping between their speech articulations and the resulting auditory feedback. In a previous study, subjects exposed to frequency-altered feedback adapted to the novel articulatory–acoustic relationship [J. A. Jones and K. G. Munhall, J. Acoust. Soc. Am. 108, 1246–1251 (2000)]. However, obtaining a precise measurement of the size of the effect was difficult because the speakers’ ‘‘habitual vocal pitch,’’ evaluated in a control condition, was used as a reference. Although an individual’s habitual pitch is reliable over long periods, there may be considerable short-term variability. In the present study, this noise was significantly reduced by asking speakers to imitate the pitch of a synthetic vowel. This paradigm allowed more precise measurements of adaptation as well as tests of generalization. In a control condition, subjects were able to reliably produce the frequency of the vowel. However, when speakers heard their vocal pitch shifted either up or down during the experimental trials, they relied on the altered auditory feedback to guide their productions. Short-term exposure to the altered feedback generated measurable aftereffects. The data are discussed in terms of a model proposed for fundamental frequency control.
Further investigations into performance metrics for underwater communications
Authors: Whitney Scott L. , Edelson Geoffrey S. , Thammakhoune Ned B. , Richman Michael S.
Published: October 2013

Determining the relationship between the performance of an underwater acoustic data communications system and the operating environmental conditions is a problem that continues to plague researchers. The complexity of the time-varying channel is difficult to measure and model. Therefore an approach that uses metrics measured from data collected at sea to characterize the channel is attractive. As expected, preliminary assessments on limited data have shown that performance depends not only on environmental conditions, but also on system implementation. By extracting a variety of metrics, a better understanding of the subset that discriminate between good and bad performance can be developed. Also by analyzing the relationship between certain metrics and performance, system limitations can be identified for re-evaluation. For example, a surprising result of the initial assessment of performance using a multichannel decision feedback equalizer on real data showed that sparseness of multipath arrivals may be an arbiter of performance [Richman et al., J. Acoust. Soc. Am. 110, 2619 (2001)]. Therefore changes to the algorithm that allows for sparse arrivals may improve performance. In this paper, a larger number of metrics from greater quantities of real-data and system configurations are measured and evaluated against equalizer results.
Application of matching pursuit algorithm for dispersive acoustic signals
Authors: Chen Chuen-Song , Miller James H. , Faye Boudreaux-Bartels G. , Potty Gopu R. , Lazauski Colin J.
Published: October 2013

Dispersive acoustic signals contain significant amounts of information concerning the shallow water environment structure. It is possible to unravel the modal propagation dispersion characteristics using a proper time-frequency analysis. Recent experiments such as ShelfBreak Primer and ASIAEX collected long range propagation data in shallow water on vertical line arrays from SUS charge explosive sources. Signals collected by the vertical arrays were processed using Morlet wavelets to observe the modal arrival structure due to group speed dispersion. Although the wavelet transform can extract the time-frequency information, it is not sufficient to get high resolution for high frequencies. The matching pursuit algorithm is an alternative approach that provides excellent spectral localization. We present an improved processing algorithm based upon the matching pursuit algorithm to analyze the data from ASIAEX-2001. This analysis yields the dispersion characteristics of the acoustic signals and clearly shows the modal arrivals, especially for higher modes. These modal dispersion diagrams from the results form the basis for long range sediment tomography. [Work supported by ONR.]
Experimental results for a prototype 3-D acoustic imaging system using an ultra-sparse planar array
Authors: Impagliazzo John M. , Chiang Alice M. , Broadstone Steven R.
Published: October 2013

A handheld high resolution sonar has been under development to provide Navy Divers with a 3-D acoustic imaging system for mine reconnaissance. An ultra-sparse planar array, consisting of 121 1 mm×1 mm, 2 MHz elements, was fabricated to provide 3-D acoustic images. The array was 10 cm×10 cm. A full array at this frequency with elements at half-wavelength spacing would consist of 16384 elements. The first phase of testing of the planar array was completed in September 2001 with the characterization of the array in the NUWC Acoustic Test Facility (ATF). The center frequency was 2 MHz with a 667 kHz bandwidth. A system-level technology demonstration will be conducted in July 2002 with a real-time beamformer and near real-time 3-D imaging software. The demonstration phase consists of imaging simple targets at a range of 3 m in the ATF. Experimental results obtained will be reported on. [Work supported by the Defense Applied Research Project Agency, Advance Technology Office, Dr. Theo Kooij, Program Manager.]
Detection of a weak target in the presence of strong interferers
Authors: Sullivan E. J. , Candy J. V. , Carey W. M.
Published: October 2013

The detection of a weak target in a hostile environment consisting of ambient noise, distant shipping, and ‘‘known’’ interferers, such as passing ships, is treated by applying a parametrically adaptive signal-processing technique. In this approach, the oceanic environment and noise sources are represented by mathematical models and directly incorporated into the processor, thereby allowing their effects to be removed from the decision function prior to target detection. It is then shown that the weak target dominates the resulting decision function. The approach recognizes the variability of the ocean environment and allows the processor to adaptively adjust its inherent parameters and underlying statistics to the changing ocean environment.
Use of amplitude without phase angle to achieve pseudo-coherent processing gain
Authors: Wagstaff Ronald A.
Published: October 2013

Processing gain as much as 3 dB per average doubling can be achieved by coherent temporal averaging (i.e., with phase), compared to 1.5 dB per doubling for incoherent averaging (i.e., without phase). However, it is not uncommon for signals to be coherently cancelled as if they never existed, or be severely attenuated. For this reason, coherent temporal averaging is seldom used. A method is presented that utilizes amplitudes to generate ‘‘pseudo-phase angles’’ (not real angles). Pseudo-phase angles are combined with the corresponding amplitudes to form pseudo-vectors for vector and coherent averaging. Thus, the large gains that are normally associated only with coherent processing can be achieved without using the real phase angles. This ‘‘pseudo-coherent’’ gain is about the same as coherent averaging gain, but signals are not cancelled. Furthermore, the pseudo-phase angles can be used to automatically detect signals. Results from measured data will be presented to illustrate pseudo-coherent gains in signal-to-noise ratio of 10 dB, minimum detectable level of 3 dB, resolution of 2×, and automatic signal detection. [Work supported by U.S. Army Space and Missile Defence Command.]
Experimental multipath time spread in a bathymetrically complex coastal environment
Authors: Di Napoli Frederick R. , Shelton Jason S. , Rozenfeld Ilya
Published: October 2013

An acoustic survey was conducted that covered both the continental shelf and slope regions in water depths from 40 m to greater than 1000 m. The types of bathymetric conditions encountered included those likely to be found in any coastal environment. At the benign end of the spectrum a relatively smooth bottom with small slopes connected the shelf and slope. In another area the shelf was relatively short and extended to water depths of approximately 100 m, followed by very steep continental slopes bordered by canyon walls. Intermediate conditions consisted of a short shelf and large continental slopes without canyon walls. Broadband (12 Hz to 4 kHz) acoustic measurements were made under strongly downward-refracting sound-speed conditions using impulsive sources at two different depths. The source at 18 m was in a deep (approximately 40 m) weak surface duct. A strong sound-speed gradient separated this source from the 86-m source depth. The impulsive data have been processed to extract a measure of the effective multipath time spread. Results will be presented showing the sensitivity to source depth, frequency range from the receiver, and bathymetric conditions.
Coherent backscatter simulation for synthetic aperture sonar
Authors: Dugelay Samantha , Brothers J. Richard , Chapman A. Sean
Published: October 2013

COSIM is a coherent backscatter simulator for generic high frequency sonars developed by QinetiQ. This model simulates acoustic backscattering in the time domain from various types of seafloor and targets, in various environmental conditions. The parameters of the model include pulse length and type, sonar characteristics, environmental properties concerning water column and sea surface and physical seafloor properties. In this paper we present descriptions of the various simulation stages, from the seabed generation to the signal simulation. Our main focus in thi paper is the introduction of spatial and temporal fluctuations within the water column and on the seabed and their detrimental effect on synthetic aperture sonar processing. Prior work on seabed clutter (Dugelay and Brothers, Proceedings Oceans 2002) and statistical analysis (Dugelay, Brothers and Heald, 142nd ASA Proceedings) is introduced into the seabed simulation module and initial results on the effect of seabed clutter density are presented. More particularly, the introduction of water column fluctuations is studied: the simulation of realistic fluctuations will be described and the effects on the backscattered signals will be analyzed. Finally, synthetic aperture sonar imaging will be shown in a variety of environmental cases and the image degradation will be compared to the environmental fluctuations.
Models of acoustic scattering from continuous and discrete heterogeneity in marine sediments
Authors: Ivakin Anatoliy N.
Published: October 2013

A description of the scattering processes in marine sediments for different types of scatterers, continuous and discrete, is given in terms of the scattering cross section per unit sediment volume and the scattering cross section per unit seabed area. However, there is a difference in the way these volume and surface cross sections are expressed through the characteristics of the scatterers. In the case of a continuous medium, they are expressed in terms of the spatial spectra of inhomogeneity (fluctuations of acoustical parameters) and the interface roughness. In the case of discrete inclusions, the cross sections are described in terms of the individual scattering functions of discrete targets and statistical distributions of their parameters (size, shape, orientation, material, etc). Some simplified expressions for the individual scattering functions of such bodies as shell fragments, rocks, and others are discussed. Examples for the size distribution functions are presented obtained from analysis of published data. Two types of models for discrete scattering are considered. In the first one, the discrete inclusions are uniformly distributed in the sediment volume. In the second model, the scatterers are placed on or near the water-sediment interface or buried at a certain depth below (a top or buried monolayer of scatterers). Note that, rigorously, the individual scattering functions should take into account the influence of the water-sediment interface. Effects which result from this influence are discussed. The frequency-angular dependencies of the seabed scattering strength for the two types of models of discrete scattering are calculated and compared to those for a corresponding continuous seabed medium with volume heterogeneity or interface roughness. [Work supported by ONR, Ocean Acoustics.]
On the role of the frozen surface approximation in small wave-height perturbation theory for moving surfaces
Authors: Keiffer Richard , Novarini Jorge , Scharstein Robert
Published: October 2013

In the standard development of the small wave-height approximation (SWHA) perturbation theory for scattering from moving rough surfaces [e.g., E. Y. Harper and F. M. Labianca, J. Acoust. Soc. Am. 58, 349–364 (1975)] the necessity for any sort of frozen surface approximation is avoided by the replacement of the rough boundary by a flat (and static) boundary. In this paper, this seemingly fortuitous byproduct of the small wave-height approximation is examined and found to fail to fully agree with an analysis based on the kinematics of the problem. Specifically, the first-order correction term from standard perturbation approach predicts a scattered amplitude that depends on the source frequency, whereas the kinematics of the problem point to a scattered amplitude that depends on the scattered frequency. It is shown that a perturbation approach in which an explicit frozen surface approximation is made before the SWHA is invoked predicts (first-order) scattered amplitudes that are in agreement with the kinematic analysis. [Work supported by ONR/NRL (PE 61153N-32) and by grants of computer time DoD HPC Shared Resource Center at Stennis Space Center, MS.]
Sub-critical insonification of buried elastic shells
Authors: Veljkovic Irena , Schmidt Henrik
Published: October 2013

In a shallow water environment a high frequency high grazing angle mine-hunting sonar approach is vastly limited by the coverage rate, making the detection and classification of buried objects using subcritical grazing incidence an attractive alternative. One of the central issues in mine countermeasurements regarding the physics of scattering from spherical shells is the isolation and the analysis of the resonant excitations of the system distinguishing the manmade elastic targets from rocks or other clutter. Burial of an elastic target in the seabed results in a variety of modifications to the scattered response caused by different physical mechanisms, geometric constrains, and intrinsic sediment properties. The aim of this research is to identify, analyze, and explain the fundamental effects of the sediment and the proximity of the seabed interface on the scattering of sound from elastic spherical shells insonified using low frequencies at subcritical incident angles. A new, comprehensive understanding of the goats98 experimental data was obtained distinguishing the effects of the acoustics environment from the resonant signature of a buried elastic target. To achieve this and to further investigate the more intricate details of the scattering process, a numerically improved, OASES-3D modeling framework was used. [Work supported by ONR.]
Directional characteristics of conformal transducers on fluid loaded elastic shells
Authors: Stepanishen Peter R. , Cox Don
Published: October 2013

A general analytic approach is presented to evaluate the directional characteristics of conformal velocity sources representing transducers on fluid loaded elastic shells. The sources/transducers are assumed to be structurally decoupled from the shell but are coupled to the shell via the fluid. The pressure field is expressed via superposition as the sum of the pressure field from the sources on a rigid shell plus the pressure field from the elastic shell assuming zero normal velocity for the sources. An in vacuo eigenvector expansion is used to describe the velocity field of the shell. The modal coefficients of the expansion for the shell are related shells via a set of linear algebraic equations to the modal coefficients of a different expansion for the surface pressure due to the sources on the rigid shell. Shadowing effects of the sources on the response of the shell are included in the formulation. Numerical results for the directional characteristics of specified circular velocity sources on rigid and elastic spherical shells are presented as a special case. The results illustrate the effects of diffraction and shell resonances on the directional characteristics of the sources in the low, mid, and high frequency regions. [Work supported by ONR.]
The prediction of noise generated by the interaction of airflow and duct discontinuities
Authors: Oldham David J.
Published: October 2013

There is a paucity of data available relating to the noise generated by ventilation system elements. This paucity arises from the difficulty in obtaining such data as it requires the use of rare and expensive combined acoustic and aerodynamic measurement facilities. In this paper a prediction technique is proposed which overcomes the need for these expensive test facilities. Discontinuities in ducts result both in the generation of flow noise and a loss of static pressure. The greater the discontinuity the greater is the loss in static pressure and the greater is the sound power generated. Over a number of years there has been considerable research aimed at establishing the correlation between the drop in static pressure across a flow spoiler and the noise generated. In this paper it is shown that for a typical duct discontinuity it is possible to predict the sound power generated from knowledge of its pressure loss characteristics. A prediction method is proposed based upon a normalized sound-power level which is a function of the Strouhal number. Such a prediction technique has enormous potential value in the design of high-velocity air distribution systems.
The location and sizing of holes and obstructions in pipes and ducts
Authors: Oldham David J. , de Salis Max H. F.
Published: October 2013

A change in the cross-sectional area of a duct or pipe due to the presence of an obstruction will modify the eigenfrequencies of that system. A technique is presented for determining the blockage area function of a pipe or duct based upon the concept of these eigenfrequency shifts but using resonance and antiresonance frequencies determined from a single measurement of sound pressure within a duct. The technique is shown to be capable of revealing the location and size of single and multiple obstructions to a high degree of accuracy. The technique has also been successfully applied to the detection, location and sizing of small holes in duct walls. The position of a hole in the duct wall is revealed as the beginning of an apparent gradual expansion in the reconstructed blockage area function emanating from an initial positive dc shift. Once the hole has been located, an impedance model of the duct incorporating the size and location of the hole and the measured wave number at the first-order duct resonance allows the determination of the area of the side hole from a simple quadratic equation.
Sound power level measurements of the noise produced by a residential split unit air conditioner
Authors: Crocker Malcolm J. , Arenas Jorge P.
Published: October 2013

The noise produced by an air conditioner may be caused by several mechanical and aerodynamic sources. This abstract presents an experimental attempt to characterize and compare the noise sources of a residential split unit air conditioner. In the split unit studied in this research, the compressor and condenser and associated fans are normally located outdoors. Therefore, they were removed from the unit and did not form part of the studies. Care was taken with the unit to separate the inlet and exhaust noise from the noise radiated from the cabinet. The measurements were made with a two-microphone sound intensity probe and these resulted in sound power level data. The sound power levels produced by radiation from the inlet, exhaust, and cabinet were obtained for five different volume flow rates. The effect on the sound power generated by removing the coil and adding a damper in the exhaust was investigated. Measurements and subjective studies show that the low-frequency sound is predominantly radiated from the exhaust and inlet. At high frequency, the cabinet noise dominates. The measuring procedure and data obtained are relevant to industry involved in development and manufacture. [Work supported by both Trane Corporation and Bruel & Kjaer.]
Ducts with spatially varying properties
Authors: Barros José Luis
Published: October 2013

A duct with a varying cross-section and/or acoustic impedance of its internal surface is represented by a series of small duct sections. Each section has parallel walls and a locally reacting internal surface with constant impedance. The effect of the transition between two ducts of a different cross-section is studied. The ducts are considered bidimensional and the characteristic equation is solved numerically, in this way a set of orthogonal modes are obtained with which the sound field can be synthesized. The amplitudes corresponding to each mode can be obtained from the boundary conditions for pressure and velocity between duct sections. Considering a number N of modes, a system of linear equations with 2N unknowns is obtained (corresponding to the modal amplitudes of the incident and reflected waves). The acoustic behavior of duct transitions is analyzed considering the three fundamental types of impedance (mass character, stiffness character, and damping). (To be presented in Spanish.)
Ship strikes and whales: Shadows, mirrors and paradoxes
Authors: Gerstein Edmund R. , Blue Joseph E. , Forsythe Steven E.
Published: October 2013

Ship collisions with whales and other marine animals occur near the surface. Here Snells law applies and can play a crucial role in the survival and behavioral ecology of marine mammals. In this study we investigated some theoretical constructs of near surface sound propagation that can render whales vulnerable to collisions. Empirical measurements support predictions and demonstrate that propeller noise directly ahead of many large vessels can become indistinguishable from the ambient noise. Large acoustic shadows in front of approaching ships and the confluence of near surface acoustic propagation effects seriously challenge the whales’ ability to detect and locate approaching ships. At the surface, ship noise profiles are loudest at the stern and off the port and starboard sides while remaining remarkably quiet at the bow. Whales with calves swimming near the surface alerted to ship sounds may seek refuge by actively swimming into the quieter shadow zones directly ahead of vessels. Once here, hydrodynamic forces could overcome calves and adults. While this behavioral scenario has not been investigated, acoustic measurements reveal a disturbing paradox, suggesting the circumstance is plausible. Further investigations may result in directional acoustic solutions that light-up these acoustic shadows and can alert whales in time to avoid injury.
Effects of boat noise on vocalizations of gray whales (Eschrichtius robustus) in Bahia Magdalena, Baja California Sur, Mexico
Authors: Ollervides Francisco
Published: October 2013

Enhanced propagation characteristic of sound underwater has led to development of excellent acoustic sensory systems among cetaceans, which use sound for individual recognition, predator detection, communication, facilitation of social cohesion, and coordination during courtship and foraging behaviors. Increased input of noise from human activities in the oceans has sparked public and scientific concern about potential effects on these animals. In Bahia Magdalena, anthropogenic noise originates mostly from boat traffic. Boat noise is similar at frequencies below 2 kHz to gray whale vocalizations; thus, it has the potential to interfere with these animals’ communication. Significant differences in ambient noise levels (chi squared=44.1, df=3, p=0.00001) were observed depending on boat traffic, biological and nonbiological contributors, and water depth at various regions throughout Bahia Magdalena. This study contributes to baseline acoustic profiles in representative habitats where whale watching occurs for future management considerations. It was evaluated whether boat noise affected duration, bandwidth, emphasized frequency, high and low frequencies, and repetition rate of the 11 different gray whale signal types by measuring and contrasting such characteristics in the presence and absence of boat noise. Monitoring these changes in vocal behavior will aid in determining if these animals are being disturbed by noise. (To be presented in Spanish.)
Impact of anthropogenic sounds on fishes
Authors: Popper Arthur N. , McCauley Robert D. , Fewtrell Jane
Published: October 2013

It is widely suspected that anthropogenic sound could impact the life and survival of marine mammals. One of the major sources of anthropogenic sounds in many parts of the world are seismic air guns used in geologic exploration. Yet there are few data on the physiological and behavioral impacts of air-guns on fishes or marine mammals. This study tested the effects of exposure to air guns on the ears of marine fishes. Pink snapper (Chrysophrys auratus) held in cages were exposed to signals from an air gun towed toward and away from the cages, mimicking the stimulus from an approaching/passing seismic vessel. Results from scanning electron microscopic examination of the ears showed extensive damage occurring weeks after exposure. Damage included deep holes in the saccular epithelium in places where sensory hair cells would be located, and/or ‘‘blebbing’’ on the surface of the epithelium suggesting dying sensory cells. While it is recognized that fishes outside of a cage might swim away from a loud sound, the results reported here suggest that very intense sounds could have a significant impact on the auditory system of fishes, and perhaps other marine organisms.
Far-field auditory evoked potentials in small and large felids
Authors: Walsh Edward J. , Armstrong Douglas L. , Curro Thomas , McGee JoAnn
Published: October 2013

The survival of all tigers existing today is seriously threatened, at least partially, as a consequence of the encroachment of civilization. As a prelude to a proposed long-term study intended to determine the impact of urban noise as an extinction pressure for indigenous tiger populations, auditory brainstem responses (ABRs) were recorded from representatives of three of the four surviving tiger substrains, Panthera tigris altacia, Panthera tigris tigris, and Pantera tigris sumatrae, along with an adult male lion (Panthera leo). Standard procedures were employed to record ABRs on location at the Henry Doorly Zoo and response features were measured along with thresholds to tone bursts spanning the empirically determined frequency response range. Threshold estimates were corrected to compensate for background masking noise by applying a correction factor generated by subtracting frequency-threshold estimates derived from gerbil measurements made on location at the zoo from frequency-threshold estimates derived from measurements made under controlled conditions in the lab from the same animal. While overall response features and input–output characteristics were similar to those observed in domestic cats and other mammals, large felids responded preferentially to very low-frequency tone bursts and poorly to high-frequency tone bursts when compared with small fields.
Biological responses to acoustical stress in fishes
Authors: Popper Arthur N. , Kane Andrew S. , Smith Michael S.
Published: October 2013

High level sound exposure, particularly for long periods, have significant effects on humans and other animals. Many species of fish are being exposed to increased ambient sounds associated with multiple sources including shipping, seismic experiments, sonars, and recreational boating. Previous efforts have focused on how such marine anthropogenic sounds affect marine mammals. However, the effects of such sounds on fishes have rarely been examined. Acoustical stress to fish is also likely to be found in many aquaculture facilities, yet little concern has been directed at the appropriate acoustical environment for optimal growth and development. We examined the effects of increased ambient sound on the hearing and overall health of fish species differing in hearing capabilities. Fish were reared in 600-L aquaria under quiet (110 dB re: 1 μPa) or noisy (170 dB re: 1 μPa) conditions and individuals were removed after different durations of noise exposure. We then measured alterations in noise-exposed fish relative to hearing capabilities (using auditory brainstem responses), pathology of the inner ear (using SEM), and stress (using plasma cortisol levels). Preliminary data suggest that susceptibility to noise-induced stress may be species-specific.
Focusing ultrasound through bone and tissue layers in the wave vector frequency domain
Authors: Clement Greg T. , White P. Jason , Hynynen Kullervo
Published: October 2013

A planar projection algorithm is combined with ray theory to propagate ultrasound through an arbitrary number of randomly oriented isotropic tissue layers. The propagation information can then be used for beam aberration correction. This method, which is intended for applications in therapeutic ultrasound, calculates or measures the space–time pressure field in a plane and uses wave vector frequency-domain methods to project the field through the media. The approach requires information obtained a priori from MRI or CT images and is valid for longitudinal propagation through tissue and bone layers at low incident angles. The algorithm is verified by propagating fields created by a 1.5 MHz, 104-element therapy array through a combination of layered materials, including plastic phantoms, fresh porcine fat-muscle layers, and ex vivo human bone samples.
Frequency and porosity dependence of acoustic properties in bovine cancellous bone
Authors: Yoon S. W. , Lee Kang Il , Roh Heui-Seol
Published: October 2013

Acoustic properties of bovine cancellous bone were experimentally and theoretically investigated in the frequency range of 0.5–1 MHz. For theoretical estimation the modified Biot–Attenborough (MBA) model was employed. Phase velocity, attenuation coefficient, and BUA of cancellous bone were described as the functions of frequency and porosity. The relative orientation between the ultrasonic beam and the bone specimens was the mediolateral (ML) direction of the bovine tibia. Since the fast and slow waves were completely overlapped, only one longitudinal wave was observed for propagation in the ML direction. The MBA model for nonrigid porous medium with circular cylindrical pores well described the experimental results of acoustic wave propagation in cancellous bone. [Work supported by BK21 Program, KRF(KRF-2000-015-DP0178), and KOSEF(2000-1-11100-002-2) in Korea.]
Fetal electrocardiograph
Authors: Rios Heriberto , Andrade Armando , Puente Ernestina , Lizana Pablo R. , Mendoza Diego
Published: October 2013

The high intra-uterine death rate is due to failure in appropriately diagnosing some problems in the cardiobreathing system of the fetus during pregnancy. The electrocardiograph is one apparatus which might detect problems at an early stage. With electrodes located near the womb and uterus, in a way similar to the normal technique, the detection of so-called biopotential differences, caused by concentrations of ions, can be achieved. The fetal electrocardiograph is based on an ultrasound technique aimed at detecting intrauterine problems in pregnant women, because it is a noninvasive technique due to the very low level of ultrasound power used. With this system, the following tests can be done: Heart movements from the ninth week onwards; Rapid and safe diagnosis of intrauterine fetal death; Location and size of the placenta. The construction of the fetal electrocardiograph requires instrument level components directly mounted on the printed circuit board, in order to avoid stray capacitance in the cabling which prevents the detection of the E.C.G. activity. The low cost of the system makes it affordable to low budget institutions; in contrast, available commercial systems are priced in U.S. Dollars. (To be presented in Spanish.)
Unique gel-coupled acoustic sensor array monitors human voice and physiology
Authors: Scanlon Michael
Published: October 2013

The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. The Army Research Laboratory’s gel-coupled acoustic physiological monitoring sensor has acoustic impedance properties similar to the skin that facilitate the transmission of body sounds into the sensor pad, yet significantly repel ambient airborne noises due to an impedance mismatch. Acoustic signal processing detects physiological events such as heartbeats, breaths, wheezes, coughs, blood pressure, activity, motion, and voice for communication and automatic speech recognition. Acoustic sensors can be in a helmet or in a strap around the neck, chest, and wrist. Although the physiological sounds have high SNR, the acoustic sensor also responds to motion-induced artifacts that sometimes obscure meaningful physiology. A noise-canceling sensor array configuration helps remove motion noise by using two acoustic sensors on the front sides of the neck and 2 additional acoustic sensors on each wrist. The motion noise detected on all 4 sensors will be dissimilar and out of phase, yet the physiology on all 4 sensors is covariant. Pulse wave transit time between neck and wrist will indicate systolic blood pressure. Data from a firefighter experiment will be presented.
Thermodynamical analysis of acoustical perturbations in the bronchial tree
Authors: Puente Margarita , Perez-Guerrero Armando , Alvarado Manuel
Published: October 2013

In the airways, very complex flows occur because of different conditions and the existence of a lot of complications: constantly changing temperature and pressure during the respiration process, a normally turbulent flow in the trachea which, in heavy breathing, remains so in the first three or four generations of airways, changes of the direction of the flow over the breathing cycle, from inspiration to expiration, etc. We also know the air that flows in the bronchial tree is perturbed by several sources such as the heart and the circulatory system, the diaphragm and stomach movements, etc., which produce sound waves. Thus an acoustical analysis of the phenomenon can lead us to a physical model which could help us to better understand the phenomena and to demonstrate the importance to clinical applications such as the pneumocardiograms. To this purpose we use a thermodynamical model that originally was developed to analyze supersonic air jets to explain the production of shock waves in the bronchial tree.
Exploit the soundscape and reformulate traffic noise goals
Authors: Kihlman Tor
Published: October 2013

‘‘Soundscape support to health’’ (www.soundscape.nu) is a 4 year research program including studies of traffic noise propagation in cities and different health effects of traffic noise. Special attention is given to the effect of access to a quiet side of dwellings. One goal of the program is to find more relevant goals than the present longterm general goal LAeq,24h<55 dB for all residents which on one hand is unrealistic and on the other hand does not imply a good environment—it is a compromise; at this level a substantial fraction of an exposed population is highly annoyed. However, the big spatial SPL variations within the city typically ranging from 40–70 dB can be systematically exploited. Traffic noise goals should therefore be reformulated to protect existing quietness and promote that all residents get access to a quiet environment within reach even though a typical level at facades facing the traffic will exceed 60 or 65 dB during a foreseeable future. In the paper how the results from the program may be used to formulate goals that are more credible than the present and that lead to decreasing negative health effects of the traffic noise are described.
The contribution of noise to perception of neighborhood satisfaction, and the probability of leaving the area
Authors: Job RF Soames , Hatfield Julie , Carter Norman L. , Peploe Peter , Taylor Richard , Morrell Stephen
Published: October 2013

When the runaways at Sydney Airport were reconfigured, noise increased in some low-noise areas and decreased in some high-noise areas (while other areas remained highly exposed and unchanged, or minimally exposed to aircraft noise). Residents were surveyed before (N=1015), immediately after, and several years after the reconfiguration. This data set allows consideration of the extent to which ratings of the neighborhood are determined by noise versus other factors (parks, air pollution, safety). Residents were also asked whether they would consider moving because of the noise. From the follow-up data we examined which features of the residents satisfaction with the area and the noise, as well as features of the residents themselves (noise sensitivity, general sensitivity, personality, home ownership) predicted considering moving and moving. These results address the issue of the importance of soundscape in residential satisfaction, relative to other factors.