bluuebunny/crossref_metadata_2025 huggingface dataset:
‘‘REC Curve’’ data measured in halls opened after 1988
Authors: Toyota Yasuhisa , Oguchi Keiji , Nagata Minoru
Published: February 2014

As the results of the studies on early reflections in auditoriums, ‘‘Reflection Energy Cumulative Curve excluding direct sound’’ (REC Curve) was introduced and defined at the ASA Hawaii meeting in 1988. In the study, early reflections up to around 80 ms after direct sound were found to be substantially important and influenced by the room shape of the auditorium. Some concert halls were designed based on ‘‘REC Curve’’ so that REC Curve up to 80 ms showed smoothly increasing curves in the auditoriums. ‘‘REC Curve’’ data measured in the halls opened after 1988 are reported in this paper with some subjective comments on the halls.
Sound coloration from (very) early reflections
Authors: Halmrast Tor
Published: February 2014

Coloration is defined as changes in Timbre/Klangfarbe. Adding a reflection automatically changes the frequency response of a signal, giving some kind of coloration. This might be looked upon as distortion. However, reflections have been a part of sound distribution since the Greek amphitheatres, indicating that some coloration must be acceptable, even wanted. The question is: Which reflections give disturbing/unwanted coloration? Most room-acoustic criteria assume that everything happening before/after a certain time is supposed to be good/bad (e.g., 50 ms/80 ms for speech/music). We need to take a closer look at the distribution of reflections within these time intervals, to investigate coloration. This paper will give results from measurements in concert halls (Oslo, Munich, Vienna), and opera houses, and compare them with psychoacoustic studies on coloration. It is shown that measurements should be done with the orchestra present on the stage/in the orchestra pit (TOR, through orchestra impulse response). Lonesome/strong reflections with a time delay about 10 ms will give box-klang-coloration. On the other side, colorating reflections might be useful and fun, used in the right way, to support bass instruments, etc. [J. Sound Vib. 232 (2000)].
When all sound is mere reflections
Authors: Talaske Richard H.
Published: February 2014

For many decades in the recent past, impulse response measurements have been performed in music and drama spaces to assess the clarity of sound and ease of communication offered on a stage or within the audience chamber. Much of the focus has been on the strength and timing of early sound reflections arriving within 80 or so ms following the direct sound. Generally, the thought and design process revolve around an unoccluded, straight-line path between source and receiver. This paper, however, presents the results of numerous studies and completed buildings in which excellent communication has been achieved in drama and music conditions where the direct sound is attenuated due to source directivity factors and/or obstructions normally encountered within rooms. Results of computer model studies, photos of completed spaces and acoustic data will be presented along with general conclusions.
Wideband and correlation techniques and their application to fisheries acoustics: Existing prototypes and future trends
Authors: Zakharia Manell E.
Published: February 2014

The aim of this work is to describe several ‘‘research sonar’’ prototypes (one-of-a-kind), to show the performance improvement by using both wideband techniques and associated echo processing procedures such as correlation, synthetic aperture, or spectral signature analysis. We will describe the improvement of fisheries sounders provided by widening the frequency range: enhanced axial resolution, smoothed spatial and angular variations. The advantages will first be illustrated by experiments on individual fish. Then, the performance of such systems will be investigated at sea using wideband prototypes. A wide range of processing algorithms will then be detailed: pulse compression, dynamic focusing, beam control on a wide frequency range, synthetic aperture, echo to echo information, etc. Some of them have been commonly used in military sonar systems, some others are still under exploration in other areas (echo–echo correlation, synthetic aperture processing of sidescan data). A multibeam approach based on wideband correlation will also be described. Finally, the performance of wideband classification of fish species at sea will be shown. The technical limitations (transducers, acoustic compatibility, real-time processing, etc.) that could limit the development of such systems will be developed and several solutions will be proposed to overcome the development complexity.
Overt visual attention in spoken sentence perception
Authors: Lansing Charissa R. , McConkie George W.
Published: February 2014

People’s eye movements and performance accuracy were recorded as they attempted to understand sentences spoken by two talkers under two conditions: vision only and vision plus low-intensity sound. Percent word-correct scores were higher for the vision-plus-sound than for the vision-only presentation and for the male compared to the female talker. Eye movement records showed a tendency to gaze at the talker’s eyes when the talker was not speaking, but to shift the gaze to the mouth and make long eye fixations when the talker was speaking, particularly under vision-only conditions and for the female talker. In a task requiring verbatim word identification, people with average speech-reading proficiency direct their gaze to the talker’s mouth most of the time during the talker’s speech production, contrary to the finding of Vatikiotis-Bateson, Eigsti, Yano, and Munhall (1998), and they produce very long eye fixations. For these people, the gaze is drawn to the mouth, not by facial motion alone, but also on some other basis that is assumed to be prior knowledge of the location of critical visual cues, with an accompanying suppression of saccadic activity. [Work supported by NIH-NIDCD Grant DC02250.]
Perception of Cantonese Parkinsonian speech
Authors: Wong Patrick C. M. , Diehl Randy L. , Ho Shu Leong , Li Leonard S. W. , Tsang Kin Lun
Published: February 2014

The current study is a continuation of our previous case study investigating the effect of reduced pitch range in Parkinsonian speech on a tone language [P. C. M. Wong and R. L. Diehl, J. Acoust. Soc. Am. 105, 1246(A) (1999)]. In the first experiment, listeners were asked to identify the last word of semantically neutral sentences produced by Cantonese-speaking Parkinson’s disease (PD) patients, normal speakers, and a resynthesized version of PD speech with expanded pitch range. Identification of normal and PD speech did not differ, perhaps due to the insignificant difference in pitch range between the two types of speech. However, listeners were better at identifying the resynthesized PD speech which contained a larger pitch range than the original PD speech. This latter result supports the theory of context-target pitch distance proposed by Wong and Diehl which states that lexical tone perception relies on a sufficiently large pitch distance between the context and target of an utterance [J. Acoust. Soc. Am. 104, 1834(A) (1998)]. In the second experiment, subjects were asked to identify the intended intonation (angry, happy, neutral, and question) of sentences produced by normal and PD speakers. Performance was better for normal speech. [Work supported by NIDCD.]
Do listeners to speech perceive gestures? Evidence from choice and simple response time tasks
Authors: Fowler Carol A. , Brown Julie M. , Sabadini-Grant Laura , Weihing Jeffrey
Published: February 2014

According to the motor and direct realist theories, listeners perceive speech gestures. The following experiments test this claim. Experiments 1 and 2 replicate the findings of Porter and Castellanos [J. Acoust. Soc. Am. 67, 1349–1356 (1980)]. Participants shadowed vowel-consonant-vowels (VCVs) produced by a model. Responses were timed. The difference between response times (RT) in simple and choice speech shadowing tasks (26 ms) is shorter than the canonical choice/simple RT difference [100–150 ms, Luce (Oxford, New York, 1986)]. This is interpreted as supporting Porter and Castellanos, in that when the task is to shadow speech, the element of choice is considerably reduced as the listener receives instructions for her response from the speech sounds she perceives. In experiment 3, the timing of gestures of the models’ speech was manipulated by extending the voice onset time (VOT) of the models’ production of voiceless stops in half of the speakers VCVs. VOTs of participants shadowed responses were measured. Our findings suggest that listeners’ productions of phonemes can be influenced by their perception of the timing of the models’ gestures in speech shadowing tasks. This provides additional support for the interpretation that participants’ shadowing responses are guided by their preception of the models’ gestures.
Intelligibility of frequency-shifted speech
Authors: Scott Jack M. , Assmann Peter F. , Nearey Terrance M.
Published: February 2014

A significant fact about speech perception is that intelligibility can be preserved when the formant pattern is shifted up or down along the frequency scale. To study the relationship between fundamental frequency (F0) and spectrum envelope shifts, we used a high-quality vocoder (‘‘Straight’’) to process a set of 280 English sentences from the Hearing in Noise Test. Upward shifts in spectrum envelope (shift factors of 1, 2, 3, or 4) were combined with upward shifts in F0 (shift factors of 1, 2, or 4). Word recognition accuracy dropped from near perfect for a spectrum envelope shift factor of 1 (unshifted speech) to 77%, 24%, and 7% for shift factors of 2, 3, and 4, respectively. F0 shifts had a small but significant effect on identification. For a spectrum envelope scale factor of 1, increasing F0 by two octaves (shift factor of 4) resulted in a 16% decline. However, for spectrum envelope shift factors of 2 or greater, increasing F0 led to an improvement in performance. The results are consistent with the hypothesis that learned relationships between F0 and spectrum envelope affect the intelligibility of frequency-shifted speech.
Application of subband adaptive filtering techniques to ultrasonic detection in multilayers
Authors: Mao Jie , Li MingXuan
Published: February 2014

The subband adaptive filtering method used in the evaluation of multi-layered steel–rubber debonding is discussed in the paper. Because the acoustic impedance of the steel differs far from that of the couplant water and the rubber, and the signal decay in the rubber is heavy, the energy of the signal reflected from the debonded rubber layers is very weak. The echoes caused by the steel/rubber interface almost mask the flaw echoes, which makes the extraction of the debonding echoes very difficult. In recent years, adaptive deconvolution [X. M. Jian, Chin. J. Acoust. 18, 280–288 (1999)], wavelet inverse filtering, homomorphic filtering and echo cancellation techniques are adopted to extract the flaw echoes, but the signal reflected from the water/steel interface is ignored because of its large amplitude. A subband adaptive filtering method is discussed in the paper, where the subband decomposition is performed using a mutual wavelet packets decomposition on the criterion of maximizing the cross-correlation between the signals. The simulations on both synthetic and real signals are presented. [Work supported by National Natural Science Foundation of China.]
Biomimetic chirplet transforms for environmentally adaptive sonar: A model of singing humpback whales
Authors: Mercado Eduardo , Frazer L. Neil
Published: February 2014

Animals that use echoes to identify and localize objects must be able to do so within a variety of acoustically complex environments. The neural processes underlying this ability can be characterized as an adaptive transformation from a one-dimensional space into an n-dimensional auditory parameter space. Neurophysiological data suggest that in mammals this transformation is highly overcomplete as well as species and experience dependent; such representations are modeled well by chirplet transforms. Chirplet-based representations of sonar signals and their echoes can be used to generate behaviorally relevant maps of acoustic features. These feature maps, which are similar to representational maps in the auditory cortex, can facilitate separation of echoes from predictable noise sources. A model of sound production and reception in humpback whales is presented to illustrate how such a feature map-based sonar might function. Singing humpbacks space themselves apart from and often approach distant, nonsinging whales, demonstrating that they are able to recognize and localize complex acoustic sources at long ranges in shallow water. Singers also modulate their sound sequences to match others they have heard, demonstrating that they are able to accurately and adaptively represent complex environmental sounds. These abilities suggest that humpback whales are well adapted for both passive and active sonar processing.
Two approximate solutions for the 3-D field in the ASA benchmark wedge
Authors: Deane Grant B. , Buckingham Michael J.
Published: February 2014

One of the current challenges to the underwater acoustics 3-D numerical modeling community is the development of benchmark geometries and solutions. Benchmark solutions to canonical problems provide a reference against which numerical models can be compared, as well as providing insight into regions or frequency regimes where the models fail. The 3-D penetrable wedge is a good candidate for a benchmark geometry because it corresponds to real-world environments (beaches and continental slopes), is tractable to a variety of numerical modelers, and has been studied analytically. Although there is no exact analytical solution available for the penetrable wedge, several approximate solutions have been developed, which may be regarded as secondary benchmarks. The results from 2 of these models for the 3-D extension of the ASA wedge benchmark will be presented.
Single bubble sonochemistry and sonoluminescence
Authors: Didenko Yuri T. , Suslick Kenneth S.
Published: February 2014

An isolated, single vapor-gas bubble pulsating in a standing acoustic field can emit flashes of light. This peculiar phenomenon is known as single bubble sonoluminescence, SBSL. We find that these bubble pulsations in water are accompanied with the formation of radicals and molecular products. In this paper, the yields of hydroxyl radicals and nitrite ions formed inside the bubble were measured for the first time. The chemical and light efficiency of acoustic cavitation and the diffusion rate of nitrogen inside the bubble during its pulsation were calculated using experimental data. The energy efficiency of OH radical formation by a single bubble is comparable to that in multibubble cavitation. However, the energy efficiency of light emission is much higher for SBSL. The diffusion rate of nitrogen inside the bubble is in good agreement with that predicted by the dissociation hypothesis. [Work supported by NAVY/ DARPA.]
The scaling of acoustic streaming for application in microfluidic devices
Authors: Frampton Kenneth
Published: February 2014

Recent interest in MEMS devices in general, and in microfluidic devices specifically, has spurred a great deal of research into the behavior of fluids in very small-scale devices. Many novel techniques have been proposed for the propulsion of fluids in small-scale devices including peristaltic and electrokinetic. More recently, investigations have considered the use of acoustic streaming, that is, the imposition of steady fluid momentum via nonlinear acoustic effects. The purpose of this talk is to give an overview of the physics of acoustic streaming, to discuss the various physical phenomena which generate the effect, and to highlight the favorable scaling issues of acoustic streaming that make it a viable alternative in microfluidic devices.
Experience and auditory brainstem development
Authors: Rubel Edwin W.
Published: February 2014

Understanding the cellular basis of experiential influences on auditory system development involves characterizing (1) the intercellular signaling molecule(s) responsible for activity-based long-term changes in targeted neurons; (2) the cascade of cellular events which alters the phenotype of the targeted neurons; and (3) the biological basis of developmental periods of enhanced brain plasticity, critical periods. I will summarize a series of experiments examining neuronal integrity in the cochlear nucleus of birds and mammals following manipulations of eighth-nerve activity. Comparisons of conductive hearing loss and TTX blockade of eighth-nerve activity along with in vitro experiments indicate that glutamate release and activation of group 1 metabotropic glutamate receptors (mGluRs) are essential for normal survival of cochlear nucleus neurons. The cascade of intracellular events determining survival or death of cochlear nucleus neurons involves regulation of intracellular free calcium by one or more mGluRs. Finally, new studies using transgenic mice are beginning to reveal biological mechanisms responsible for developmental changes in cellular responses to afferent deprivation. I will present recent data showing that manipulations of bcl-2 gene expression dramatically alter the critical period of susceptibility to afferent deprivation. [Research supported by grants from NIH/NIDCD.]
Absorption of sound in the Martian atmosphere
Authors: Bass Henry E. , Chambers James P.
Published: February 2014

Future missions to the planet Mars might include microphones to listen for sounds in the tenuous Martian atmosphere. The chemical composition of the atmosphere is well established by previous missions and ground based observations. The dominant constituent is CO2 with a minor amount of N2 and argon and smaller amounts of H2O. The factors important to compute the absorption of sound in a gas are reasonably well known, the most uncertain being the relaxation time of CO2 at the low temperatures encountered (200 K–300 K). By extrapolating higher temperature measurements of relaxation times, analytical expressions have been developed for the absorption due to viscosity and thermal conduction (classical absorption), rotational relaxation, and vibrational relaxation. Calculations are presented for a surface level pressure of 6 millibars (600 Pa). The absorption at mid-audio frequencies (500 Hz) is 0.03 (200 K)–0.1 (300 K) Npm−1. This is about 100–500 times greater than for the earth’s atmosphere (depending upon relative humidity).
Diffuse backscattered ultrasound for material characterization
Authors: Burkhardt John
Published: February 2014

An ultrasonic technique is proposed that allows for the characterization of scattering materials by the Legendre moments of their differential scattering cross section per unit volume. Estimates of Legendre moments are determined from an ultrasonic backscatter theory that models acoustic propagation in the medium as a time-dependent diffusion process. Monte Carlo simulations are presented which support the proposed technique. Initial experimental progress will be reported.
Bayesian signal processing in acoustics: detection, estimation and tracking
Authors: Sibul Leon H.
Published: February 2014

A tutorial introductory lecture on Bayesian signal processing for detection, estimation, and tracking is presented. After a brief historical overview, Bayes rule and risk are defined and used for development of detectors that minimize Bayes risk. Detectors that minimize Bayes risk are called Bayes detectors. Bayes risk in statistical signal processing is the expected cost of making a wrong decision. The decision process of deciding between to mutually exclusive and exhaustive alternatives (i.e., an echo and noise are present versus noise only is present) is a binary hypothesis test or detector. We show how Bayes detectors are related to the maximum likelihood test and Neyman–Pearson and minimax criteria. Multiple hypotheses tests are also reviewed. Estimate of random parameters that minimize the risk are called Bayes estimates and the resulting risk, the Bayes risk. Minimum mean square error (MMSE), MAP (mode of the posteriori density) and other estimates can be derived using appropriate cost functions. Sequential application of Bayes rule can be used to derive Wiener and Kalman filters. Some of the basic difficulties and issues of Bayesian signal processing will be discussed. [Supported by ONR, Code 333, Les Jacobi, Program Officer.]
The North Pacific Acoustic Laboratory (NPAL) experiment.
Authors: Colosi J. A. , Cornuelle B. D. , Dushaw B. D. , Dzieciuch M. A. , Howe B. M. , Mercer J. A. , Spindel R. C. , Worcester P. F. ,   The NPAL Group
Published: February 2014

The North Pacific Acoustic Laboratory program augmented the existing ATOC acoustic network with a sparse, two-dimensional receiving array installed west of Sur Ridge, California, from July 1998 through June 1999, to receive transmissions from the 75-Hz ATOC source north of Kauai. The NPAL array consisted of four 20-element vertical arrays, each with a 700-m aperture, and one 40-element vertical array with a 1400-m aperture. The arrays were deployed transverse to the 3900-km acoustic path from the Kauai source and had a total horizontal aperture of 3600 m. Data collected with the billboard array and the U.S. Navy SOSUS receivers are being used (i) to study the temporal, vertical, and horizontal coherence of long-range, low-frequency resolved rays and modes, (ii) to study 3-D propagation effects, (iii) to examine directional ambient noise properties, and (iv) to improve basin-scale ocean nowcasts via assimilation of acoustic data and other data types into models. In addition to acoustic data, environmental data along the path from the Kauai source to the billboard array were acquired by two oceanographic sub-surface moorings and by two XBT/CTD/ADCP transects along the path. The experiment will be described and some preliminary results presented.
Horizontal refraction of acoustic signals retrieved from NPAL billboard array data
Authors: Voronovich Alexander G. , Ostashev Vladimir E. , Colosi J. A. , Cornuelle B. D. , Dushaw B. D. , Dzieciuch M. A. , Howe B. M. , Mercer J. A. , Spindel R. C. , Worcester P. F. ,   NPAL Group
Published: February 2014

A comprehensive, long-range sound propagation experiment was carried out with the use of the billboard acoustic array of the North Pacific Acoustic Laboratory (NPAL) in 1999. The antenna consisting of five vertical line arrays was deployed near a California coast and received broadband acoustic signals transmitted from Hawaii over a distance of about 4000 km. Acoustic signals propagating over such a long distance might exhibit noticeable horizontal refraction. The paper will present results of processing the NPAL data to infer horizontal refraction angle (HRA) as a function of time. Different methods were used for determining HRA. The first approach employed cross correlation of the acoustic signals at different VLAs. Time delay corresponding to maximum of cross correlation is related to HRA assuming the angle is approximately the same for all rays (or modes). The second method used modal representation of the arriving broadband signals. The dependency of the amplitudes of acoustic modes on mode number, frequency, and arrival angle was determined independently within narrow frequency bins, and then the results were averaged over whole frequency range. This method allowed, in particular, to evaluate angular width of the arrived signal, which appeared to be of the order of a few milliradians.
On ‘‘ray-like’’ arrivals in the deep-ocean shadow zone of megameter range acoustic transmissions
Authors: Dushaw Brian , Colosi J. A. , Cornuelle B. D. , Dushaw B. D. , Dzieciuch M. A. , Howe B. M. , Mercer J. A. , Spindel R. C. , Worcester Peter F. ,   NPAL Group
Published: February 2014

Receptions of long-range acoustic transmissions by deep hydrophone arrays in the Pacific and Atlantic often have ‘‘ray-like’’ arrivals that occur in the shadow zone of the predicted time front. These ‘‘ray-like’’ arrivals can frequently be identified with the cusps of the predicted time front, but the receivers are up to 750 m below the depth of the cusps. Preliminary calculations show that the observed acoustic energy is not accounted for by errors in the sound speed, leakage of acoustic energy below the cusps as predicted by the full wave equation, or scattering due to internal waves. Data obtained during experiments in the Atlantic and Pacific will be reviewed. Experiments that have been conducted with receivers of vertical line arrays have not had receivers deep enough to observe this phenomena. The effect is seen when bottom-mounted or midwater acoustic sources are used. These data present a number of problems: If the ray paths are wandering all over the water column, why are predictions of ray travel times usually accurate? How does the energy loss associated with these data increase the attenuation of very long-range acoustic transmissions? Without knowing the forward problem, how can these data be used to determine oceanographic information?
A comparison of ocean ambient sound levels after 30 years for a coastal site off California
Authors: Andrew Rex K. , Howe Bruce M. , Mercer James A. , Dzieciuch Matthew A. , Colosi J. A. , Cornuelle B. D. , Dushaw B. D. , Dzieciuch M. A. , Howe B. M. , Mercer J. A. , Spindel R. C. , Worcester P. F. ,   NPAL Group
Published: February 2014

As part of the North Pacific Acoustic Laboratory project, ambient sound data from 1994 to the present has been collected. Long-term averages of these data from a receiver on the continental slope west of Point Sur, CA, are compared to earlier measurements made at the same site over 1963–1965 by Wenz [Wenz, J. Underwater Acoust. 19 (1969)]. The levels Wenz reported fall below our 10% quantile from 5 Hz to 50 Hz, rise to the 50% quantile (i.e., the median) at 100 Hz, and again fall below the 10% quantile by 250 Hz. Wenz removed highly variable ‘‘transient’’ data before calculating his averages. We mimicked his processing with the NPAL data and obtained a result which is virtually indistinguishable from the median, which is approximately 1 dB below the (dB) mean of each one-third octave band. Hence, our median levels are directly comparable to Wenz’ results, and this comparison shows that the 1994–2000 levels exceed the 1963–1965 levels by 9 dB or less below 100 Hz and again at 250 Hz, but are roughly similar at 100 Hz. [Work sponsored by ONR.]
Acoustic simulation and auralization in architectural design practices
Authors: Ciao (Cao) Quinsan
Published: February 2014

This paper is dedicated to predictive relationships between space design and acoustic performance in architectural practice through auraliza-tion. With such a relationship, design alternatives can be evaluated subjectively, as well as objectively, without being constructed. In traditional practice, designers rely on vague experiences and rough estimates to predict acoustic effects while designing architectural spaces. Acoustic analysis and predication are seen as a luxury remedy and only affordable in large-scale theaters and concert halls. The recent available personal-computer-based auralization technologies brought the possibility of applying the latest science and art of architectural acoustics into design practices. Case studies presented in this paper illustrate that the auralization technology makes it possible for potential occupants as well as designers to evaluate the acoustic performance of a design by hearing it directly before a decision to build is made. They also illustrate that the auralization is a powerful tool for the general public to uncover everyday acoustic problems in common building types that have been constantly harming their well being and would otherwise be undetected. Furthermore, they demonstrate that auralization is an effective means to evaluate noise effect on subjective perception where the noise effect is signal context dependent.
Whistle repertoire of Pacific white-sided dolphins (Lagenorhynchus obliquidens) at the John G. Shedd Aquarium.
Authors: Whitten Julie L. , Thomas Jeanette A.
Published: February 2014

Whistles of Pacific white-sided dolphins (Lagenorhynchus obliquidens) at the John G. Shedd Aquarium were studied to determine: (1) whistles associated with a particular individual, (2) if whistles of isolated dolphins differed from whistles from dolphins in a group, (3) time and/or frequency variables important in classification, and (4) whistle types. Individual dolphin whistles were recorded in an isolated pool using a hydrophone and a Telex recorder. Whistles were recorded from dolphins in a group setting using the same hydrophone, but with a Marantz cassette recorder. Whistles were digitized using Canary software. Frequency and time measurements were taken from power spectra and spectrograms. ANOVA, principle component analysis (PCA), discriminate analysis (DFA), and cluster analysis were performed. Whistles were classified visually into six types. There were no significant differences between whistles from isolated or social dolphins. PCA showed duration of the series, number of whistle in the series, maximum frequency, minimum frequency, and peak frequency were important in classification. DFA showed dominant bandwidth, duration of first whistle, harmonic structure, maximum frequency, and peak frequency were important in categorizing types. Using the variables in PCA, cluster analysis separated the whistles into different types than those classified visually. This study provides no evidence of individualized signature whistles.
Adaptive ultrasonic imaging using SONOLINE Elegra
Authors: Liu D-L. Donald , Sutcliffe Pat , Lazenby John , McDermott Bruce , Von Behren Pat , Kim Jin
Published: February 2014

Adaptive correction of the effects of propagation through inhomogeneous tissue is critical to the improvement of current ultrasonic imaging systems. Currently, estimation and correction of time-delay errors is more feasible than other more sophisticated approaches. Data acquisition, time-delay estimation and compensation have been implemented on the SONOLINE Elegra system using the system CPU, the Crescendo image processor, and the existing front-end electronics. Experimental results with this implementation will be reported. The effects of compensating the transmit beam is studied using the waveform similarity factor and single transmit imaging. On an RMI404 phantom plus a 1-D aberration layer with a rms time fluctuation of 40 ns and correlation length of 5 mm, the waveform similarity factor of randomly scattered waveforms improved from 0.362 to 0.477 by iteration. Correspondingly, the −20 dB lateral resolution improved from 1.62 to 0.77 mm, and the image contrast improved by 8.5 dB (speckle region is 6 dB brighter while echo-free region is 2.5 dB darker). Experiments with a 2-D aberration layer and with a special phase aberration phantom showed less image improvements. Preliminary body scans with adaptive imaging showed improved image contrast and details in some cases but the results are mixed and influenced by such factors as isoplanatic patch size and complex scattering structures. [Study partially supported by NIH R29 CA81688.]
A PVDF long time-constant force sensor
Authors: Foulk Aaron M. , Hughes W. Jack
Published: February 2014

A low-profile large-area underwater force sensor was desired to measure quasistatic forces on a rigid structure. The design for a PVDF sensor (a low-profile piezoelectric) intended for use in measuring sustained (10-s) impact forces with minimal error is presented. The final sensor design integrates a PVDF bimorph piezoelectric element and long time constant charge amplifier electronics into a 1-in. diam by 3/8-in. waterproof package. This work addresses design issues including electronics design to maximize the useful time constant, piezoelectric material selection, thermal design and simulation to minimize pyroelectric effects and noise minimization efforts. [This work was supported by NSWC-CD and ONR.]
Note-by-note synthesis is not enough
Authors: Dannenberg Roger B.
Published: February 2014

Traditional analysis and synthesis of musical tones are based on the idea that music can be deconstructed into note units that can be individually synthesized and recombined to create music. This ‘‘divide and conquer’’ strategy is natural for scientists and engineers, but it does not always work well in practice. In particular, brass instrument tones in a musical context are quite different from brass tones produced in isolation. Synthesis methods that are capable of reproducing individual tones fail to sound realistic when these tones are sequenced to produce a musical phrase. The combined spectral interpolation synthesis (CSIS) method uses a fairly simple spectrally based model in which the dynamically changing spectrum is a function of fundamental frequency and rms amplitude. The spectrum function is determined by measuring actual acoustic performances. The synthesis model must be controlled by appropriately evolving frequency and amplitude controls. A rule-based system computes these controls from a machine-readable version of a musical score, which includes slurs and other articulation markings. The rules take musical context and phrasing into consideration. The combination of musical context and a good synthesis model results in greatly improved synthesis.
A miniaturized micro-machined thermoacoustic cooler
Authors: Chen Reh-Lin , Chen Ya-Chi , Chen Chung-Lung , Tsai Chialun , DeNatale Jeff , Nelson Jeff
Published: February 2014

A thermoacoustic cooler of miniature scale with a micro-machined stack has been numerically modeled and experimentally realized. deltae and Fluent were used to perform the numerical modeling and simulation. The acoustic pressure, velocity, and temperature profiles in the stack and exchangers were simulated. The stack is manufactured using MEMS technology for precise dimension control and flexible geometry design. The MEMS stack as thick as 4.2 mm with high aspect ratio (1/50) thin rib structures, 10 to 15 μm, have been realized. Commercially available PZT drivers were initially used to deliver acoustic power into the resonator at around 4 kHz. A more powerful acoustic driver design using PLZT is under development. The simulation result, device performance, and system integration will be reported. [Work supported by DARPA.]
Calculation of residual signal features for gear fault detection: Physics and signal processing
Authors: Reichard Karl M.
Published: February 2014

The vibration signal produced by mating gears can be decomposed into two components—a ‘‘mean’’ component due to surface imperfections present when the gear is manufactured and elastic tooth deformations, and a ‘‘dynamic’’ component due to wear and gear tooth damage. The mean component is responsible for the gear mesh frequency and its harmonics and typically dominates the measured vibration signal; the dynamic component, or residual error signal, contains information about evolving damage. A number of techniques exist for extracting the residual error signal from measured vibration signals that require removal of the great mesh frequency and its harmonics from the measured vibration signal. Several techniques for computing gear health based on the residual error signal are compared and the effect of the technique used to remove the mean signal component is examined. [Work supported by ONR through the Accelerated Capabilities Initiative (Grant Number N00014-96-1147.]
Masking by harmonic complexes with different phase spectra in zebra finches
Authors: Lauer Amanda M. , Dooling Robert J. , Leek Marjorie R. , Lentz Jennifer J.
Published: February 2014

Temporal waveform characteristics differentially affect masking by harmonic complexes in birds and humans. In birds, complexes with relatively flat temporal envelopes are more effective maskers than complexes with highly modulated temporal envelopes. Flat temporal waveforms constructed using positive and negative Schroeder-phase algorithms result in large masking differences in humans, but little masking difference in birds. This effect may be related to differences in the cochlear phase characteristics in the two species. A psychophysical estimate of the phase characteristic has been reported in humans by finding the phase spectrum of a harmonic masker that produces the least masking. Here we estimated the phase characteristic for zebra finches using operant conditioning methods to measure masked thresholds for tones embedded in harmonic complexes with phases selected according to scaled modifications of the Schroeder algorithm. There was little difference between birds and humans when the scalar was between 0.0 and −1.0 (i.e., negative Schroeder phases), but humans showed less masking than birds when the scalar was positive. These results may reflect a more linear phase characteristic along the avian cochlea. [Work supported by NIH R01 DC00198 and NSRA DC00046.]
Potential for contrast agent-induced endothelial cell injury in rabbit arteries exposed to pulsed ultrasound
Authors: Zachary James F. , Frizzell Leon A. , O’Brien William D.
Published: February 2014

No known meaningful health risks have been reported following the use of microbubble ultrasound echogenic contrast imaging agents in the United States. We designed a preliminary study to examine the potential for injury to endothelial cells in vivo following the interaction of intravascular contrast agent with ultrasound. We used a focused f/1 3.1-MHz, transducer that had in situ (at the skin) peak rarefactional and compressional pressures of 20 MPa and 46 MPa, respectively, 1.0-kHz PRF, 1.2-μs pulse duration, 180-s exposure duration, and MI of 5.8. The central auricular artery of a rabbit ear was exposed and then contrast agent administered intravenously in the lateral vein of the contralateral ear. The central auricular artery was again exposed to ultrasound at additional sites. No significant lesions were observed in arteries of rabbits evaluated immediately following exposure. When evaluated 24 or more hours after exposure, necrosis of vascular endothelial cells and subjacent smooth muscle cells, early reparative responses, leukocyte margination, and thrombosis were observed. Because of the wide use of echocardiography and contrast agents, the described vascular phenomena need additional evaluation for short and long term effects related to thrombosis and atherosclerosis in at risk patients. [Supported by NIH Grant No. HL58218.]
Acoustic vaporization of single droplets
Authors: Kripfgans Oliver D. , Fowlkes J. Brian , Carson Paul L.
Published: February 2014

It has been observed in the past that droplets in emulsions can be vaporized into gas bubbles by the application of acoustic tone bursts. This paper will show the vaporization of single albumin stabilized droplets as they are exposed to single acoustic tone bursts. An optical microscope was used to monitor single droplets in a flow tube (200 μm diameter). The flow tube was mounted in a small water tank with degassed and heated water (37°C). A single-element focused transducer with a center frequency of 10 MHz was aimed at the intersect of the tube and the optical beam. A highly dilute droplet emulsion was injected into the flow tube and a special syringe setup was used to move the fluid column in the flow tube back and forth to position individual droplets in the volume of interest. A single sinusoidal tone burst (33 cycles at 10 MHz) was sufficient to transition single droplets in the range from 5 to 15 μm diameter. The formation of the corresponding gas bubbles was monitored and measured in the range of 30 to 90 μm. [Work supported by PHS Grant No. R01HL54201 and US Army Grant No. DAMD17-00-1-0344.]
Hydrophone guided transcranial beam steering
Authors: Clement Greg , Hynynen Kullervo
Published: February 2014

A new method for focusing ultrasound energy in brain tissue through the skull bone is investigated. The procedure is designed for use with a multielement therapeutic transducer array and a small catheter-inserted hydrophone receiver placed in the brain in order to guide the array’s focus over a volume of tissue about the receiver. When performed at high intensity, cells within this volume are destroyed. The present study tests the feasibility and range of the method using ex vivo human skulls. The skull is placed between a focused ultrasound array and the receiver. Acoustic phase information is obtained from the receiver and used to both electrically shift the beam to new locations as well as correct aberrations due to the skull bone. The method is applied to a 104-element 1.1-MHz array and 120 elements of a 500-element 0.81-MHz array. Using these array configurations it is determined that the method can reconstruct and steer a focus over a distance of 60 mm within the brain. Application of this minimally invasive technique for ultrasound brain therapy and surgery is also demonstrated.
A 2.5 kHz magnetostrictive tonpilz sonar transducer design
Authors: Butler Stephen C.
Published: February 2014

Naval Undersea Warfare Center has fabricated and tested a 2.5 kHz magnetostrictive sonar transducer to validate various modeling techniques. The transducer selected is a longitudinal vibrator Tonpilz type consisting of Terfenol-D driver, tail mass, radiating head mass, and stress rod bolt with 21 MPa (3000 psi) prestress. The Terfenol-D drive rod is interlaced with three samarium cobalt magnets, one in the center and one on either end magnetically biasing the Terfenol to 60 kA/m (750 Oe). Both the Terfenol-D rods and magnets were laminated to reduce eddy currents. The magnetic circuit is comprised of pole piece discs on each end of the Terfenol-D magnet assembly and an external magnetic cylinder (return path) made of a high-permeability, high-resistivity, high-saturation powdered metal ‘‘T2.’’ The transducer has a 25 cm (9.8 in) diameter radiating face (piston), is 28 cm (11 in) long, and weighs 15 kg (32 lb) without the housing. It is 41 cm (16 in) long and 25 kg (56 lb) with the underwater housing. The measured results are compared to a finite element model using ‘‘ATILA’’ and distributed plan wave element model ‘‘TRN.’’ The coupling coefficient, permeability and mechanical losses effects for different prestress loads were measured on a resonant Terfenol ‘‘dumbbell’’ device. The in-water measured results indicate a mechanical Q of 2.5, an effective coupling coefficient of 0.36, an electro-acoustic efficiency of 60%, beam pattern directivity index of 6 dB, a maximum source level of 214.6 dB re 1uPa/m at 15 Amps ac drive and bandwidth of 2 kHz to 5.4 kHz ± 1.5 dB. Harmonic distortion was also measured for various drive levels. [Work supported by ONR.]
US versus international environmental noise policies—a proposed agenda for the next decade
Authors: Finegold Lawrence S.
Published: February 2014

During the past decade, there has been significant efforts in both Europe and Asia to develop new environmental noise control policies. During the same time in the US, there have been few major improvements in our national environmental noise policies, coupled with decreased levels of funding for noise research. The improvements in environmental noise policies being seen in Europe and Asia are due to an increasing awareness of the negative impacts of these exposures on the overall health and welfare of the exposed populations, and an awareness of the costs to society for these exposures. In particular, the rapidly evolving set of European Commission Noise Directives and the World Health Organization ‘‘Guidelines for Community Noise’’ represent a new, more aggressive philosophy concerning the steps required to minimize environmental noise exposure. In addition, the European Commission is adopting stringent noise emission criteria for a wide range of products, which could severely hinder US efforts to compete in the European marketplace. In response to this high level of international activity, it is proposed that the US embark on a 10-year effort to revitalize our national environmental noise policies. A description of a proposed philosophy for this program is presented.
Perception of periodicity strength in chinchillas
Authors: Shofner William P.
Published: February 2014

In stimulus generalization paradigms, an animal is trained to respond to a particular stimulus, and behavioral responses are then measured to probe stimuli that vary systematically along a given stimulus dimension. Unlike discrimination tasks, responses to probe stimuli are not reinforced in generalization paradigms. A generalization gradient suggests how closely the probe stimuli are perceived by the animal to resemble the training stimulus and is consistent with the hypothesis that the animal possesses a perceptual dimension related to the stimulus dimension. Chinchillas were trained to discriminate a cosine-phase harmonic tone complex from wideband noise. Probe stimuli consisted of random-phase harmonic tone complexes and infinitely iterated rippled noises. These stimuli vary in periodicity strength as measured by autocorrelation and generate a continuum in the perception of pitch strength in human listeners. Generalization gradients obtained from chinchillas are related to the height of the first peak in stimulus autocorrelation functions, suggesting that chincillas possess a perceptual dimension related to stimulus periodicity strength. Comparison of generalization data to magnitude estimation data suggests a greater influence of stimulus envelope for the perception of periodicity strength in chinchillas than for the perception of pitch strength in human listeners. [Work supported by NIDCD P01 DC00293.]
Effects of age and hearing loss on discimination of silent gaps in dynamic stimuli
Authors: Lister Jennifer , Tarver Kenton , Cyr-Kriley D’Arcy
Published: February 2014

Temporal cues in speech occur between signals that are dynamic (changing in frequency and duration). Older listeners with and without hearing loss often experience difficulty discriminating these temporal cues important for speech understanding. This study was designed to measure silent gap discrimination between dynamic stimuli for three groups of listeners: (1) young with normal hearing; (2) older with normal hearing; and (3) older with sensorineural hearing loss. Synthetic stimuli were designed to simulate four speechlike sounds (/s/, /a/, /eI/, /b/) arranged in six pairs separated by a silent gap (/s-a/, /s-eI/, /a-a/, /eI-eI/, /b-a/, /b-eI/). Two conditions of duration were imposed upon the six speech sound pairs: (1) duration of each marker fixed at values typical for the speech sounds simulated and (2) duration of each marker varied randomly within a range appropriate for each speech sound simulated. The task was a 2I/2AFC procedure targeting 70.7% correct discrimination. Results indicate that gap discrimination for frequency dynamic markers deteriorates with age and is poorer for random duration conditions than for fixed duration conditions. Significant correlations were found between age and gap discrimination and between hearing sensitivity and gap discrimination. [Work supported by USF Research and Creative Scholarship Grant No. 1219-933-RO.]