bluuebunny/crossref_metadata_2025 huggingface dataset:
Cavitation modeling and diesel engine cylinder liners
Authors: Chandekar Gautam , Pardue Sally
Published: October 2013

A common occurrence of cavitation damage is the waterside pitting of a wet sleeve liner in a diesel engine. The automotive industry utilizes an ultrasonic test of 20 kHz according to ASTM standards to quantify the effectiveness of engine coolant additives to prevent damage. However, recent tests indicate a mismatch between the ultrasonic test results and actual engine test runs. The focus of this study is to generate numerical models of bubble dynamics using already published literature. In most of the published papers higher-range frequencies (ultrasonic >15 kHz) are used. It is useful to explore the results of lower excitation frequencies as the vibrating frequencies of a diesel engine liner are between 500–9000 Hz. A Rayleigh–Plesset equation, nonlinear in nature, is used to plot the relation between bubble radius and time. Plots of the numerical solution from MATLAB are compared with plots published in the literature. Results from when the frequency of excitation is changed to the liner wall frequency and the fluid properties are changed to approximate engine conditions will be presented. Future work will examine the energy released by the bubble collapse and its correlation with erosion measured as mass change in a standard test button.
Horizontal plane localization in children
Authors: Goshorn Edward L. , Goshorn Jennifer D. , Cone E. Mary
Published: October 2013

Recently, an ASHA (1996) task force on auditory processing disorders (APD) recommended the assessment of several psychoacoustic processes for identifying APD. One of the processes listed was localization. To date, little data exist on localization capabilities in children. Therefore, this project investigated the feasibility of assessing localization in children with the purpose of developing an APD screening test. Six children, age 6.5 to 7.5 years, have thus far been evaluated. This age range was chosen because it is an optimum age, for educational purposes, to identify APD. Three stimuli were used: a 500-Hz tone, a 4000-Hz tone, and NU-CHIPS monosyllabic words. Tone duration was 1 s; the average word duration was 469 ms. Right–left localization was evaluated at 45 and 315 deg azimuth and front–rear localization at 0 and 180 deg. Each source was presented 24 times in random order to each subject. Although the data were highly variable, results revealed significantly better localization for right–left (88.2%) than for front–rear (80.5%). Within the front–rear condition, performance was better for rear (84.7%) than for front (76.4%) localization. There was no significant difference between right versus left localizations. Across stimuli performance was best for 500 Hz and poorest for words.
Experimental and analytical study of active control of energy transmission through double walls using novel piezoelectric actuators
Authors: Gao Jianxin , Cheng Li
Published: October 2013

Active noise control has recently been used to increase the sound transmission loss of double wall structures. Vibration energy transmission through a double-plates system is investigated experimentally and analytically in this paper. Novel high performance actuators which use two curved THUNDER actuators as active driving components are developed and mounted between the two plates to control the energy transmission in the double-plates system. The Rayleigh–Ritz method and eigenfunction expansion theorem are used to resolve arbitrary boundary conditions of plates, and the feedforward control strategy is employed in this paper. The time average power transmission between the source, actuators and receiver plate are discussed and utilized as a cost function to obtain optimal control. The optimal control voltages for actuators are obtained by minimizing the cost function. A double-plates system connected by four actuators is set up experimentally in order to verify the models and formulations by comparing with analytical results. The analytical and experimental data show that the new actuator exhibits excellent performance on active control of power transmission.
Toward data-driven modeling of dynamic vocal-tract data
Authors: Sethy Abhinav , Narayanan Shrikanth , Lee Sungbok , Byrd Dani
Published: October 2013

Speech production modeling relies on various forms of biometric measurements for getting articulatory data. Recent advances in real-time magnetic resonance imaging (rtMRI) capabilities [Narayanan et al., J. Acoust. Soc. Am. 113, 2258 (2003)] which make it possible to capture vocal tract images at 24-fps promise to illuminate finer details of speech production. This study presents our first effort toward automatically constructing statistical models of the vocal tract from rtMRI data. We present an automated method of extracting the regions of interest from image sequences based on Kalman snakes and optical flow [Cootes et al., IVCV July 1994]. The time resolution of this image tracking system is improved by incorporating information from parallel vocal tract movement data obtained by the electromagnetic articulography (EMA) system [Perkell et al., J. Acoust. Soc. Am. 92]. EMA data provide kinematic information such as velocity and acceleration at several points along the vocal tract. Data from segmentation and tracking are merged with information from EMA and from acoustic analysis of speech in order to obtain a time series of feature vectors. Feature space reduction and statistical parametrization schemes such as PCA are then applied to get parametric models for the articulatory system. [Work supported by NIH Grant No. DC 03172.]
The specificity of lexical confusability effects on coarticulation
Authors: Scarborough Rebecca
Published: October 2013

Brown (2001) demonstrated that speakers adjust their production of coarticulation to accommodate potential lexical confusability (the possibility of one word being misheard as another), and that listeners’ lexical recognition is facilitated by such adjustments. Speakers produced confusable, ‘‘hard’’ words (those with low-usage frequencies and many frequent, phonologically similar neighbors) with significantly more coarticulation than less confusable, ‘‘easy’’ ones (with high frequencies and few, low-frequency neighbors). The current study investigates whether these adjustments are general, applying to any potentially confusable words, or whether the adjustments are sublexical, sensitive to the particular neighbors a given word has. A frequency-balanced set of ‘‘easy’’ and ‘‘hard’’ words containing a vowel+nasal consonant sequence has been found such that half are confusable by the nasal and half are not. Six speakers read these words twice in carrier sentences. The degree of nasal coarticulation during the vowel is measured acoustically. From this it will be seen whether the coarticulatory cues to a segment are more enhanced (i.e., there is more coarticulation) in words confusable by that segment than in words with no neighbors differing by that segment. Preliminary results suggest that coarticulatory adjustments in response to lexical confusability are made at the word level rather than sublexically.
An integrated analysis of speech and gestural characteristics in conversational child–computer interactions
Authors: Yildirim Serdar , Montanari Simona , Andersen Elaine , Narayanan Shrikanth S.
Published: October 2013

Understanding the fine details of children’s speech and gestural characteristics helps, among other things, in creating natural computer interfaces. We analyze the acoustic, lexical/non-lexical and spoken/gestural discourse characteristics of young children’s speech using audio-video data gathered using a Wizard of Oz technique from 4 to 6 year old children engaged in resolving a series of age-appropriate cognitive challenges. Fundamental and formant frequencies exhibited greater variations between subjects consistent with previous results on read speech [Lee et al., J. Acoust. Soc. Am. 105, 1455–1468 (1999)]. Also, our analysis showed that, in a given bandwidth, phonemic information contained in the speech of young child is significantly less than that of older ones and adults. To enable an integrated analysis, a multi-track annotation board was constructed using the ANVIL tool kit [M. Kipp, Eurospeech 1367–1370 (2001)]. Along with speech transcriptions and acoustic analysis, non-lexical and discourse characteristics, and child’s gesture (facial expressions, body movements, hand/head movements) were annotated in a synchronized multilayer system. Initial results showed that younger children rely more on gestures to emphasize their verbal assertions. Younger children use non-lexical speech (e.g., um, huh) associated with frustration and pondering/reflecting more frequently than older ones. Younger children also repair more with humans than with computer.
Cheating Heisenberg: Achieving certainty in wideband spectrography
Authors: Fulop Sean
Published: October 2013

The spectrographic analysis of sound has been with us some 58 years, and one of the key properties of the process is the trade-off in resolution between the time and frequency dimensions in the computed graph. While spectrography has greatly advanced the development of phonetics, the uncertainty principle has always been a source of frustration to phoneticians because so many of the interesting features of speech must be observed by computing Fourier spectra over very short time frames—i.e., using a ‘‘wideband’’ spectrogram. Since the uncertainty relation between time and frequency is unbreakable, the only option for improvement is to make a new kind of spectrogram that does not graph time and frequency. An algorithm is described and demonstrated which computes a new kind of spectrogram in which Fourier transform frequency is replaced by the channelized instantaneous frequency, and time is adjusted by the local group delay. The theory behind this procedure was clarified in Nelson [J. Acoust. Soc. Am. 110, 2575–2592 (2001)]. The resulting wideband spectrograms show dramatically improved resolution of speech features, which will be demonstrated with sample figures. It is thus suggested that phoneticians should be more interested in the instantaneous frequency spectrum than in the Fourier transform.
Control of closure/constriction duration in lingual consonants
Authors: Lofqvist Anders
Published: October 2013

This study examines tongue movements in the production of lingual consonants where the duration of the oral closure/constriction is varied for linguistic purposes. Earlier work has shown that the tongue continues to move during the closure/constriction. The magnitude of the movement path during the closure/constriction is influenced by the vowel environment. Since the tongue has to stay in contact with the hard palate to maintain the closure/constriction, one might expect that the movement during the closure will be about the same for short and long consonants. To maintain the contact, a speaker would thus have to make a slower movement for the long consonants. Tongue and jaw movements were recorded in native Japanese speakers using a magnetometer system. Preliminary results for three speakers show that the closure/constriction duration for the long consonants was usually more than twice as long as that for the short consonants. The results also show a slightly longer movement path during the closure/constriction for the long consonants. As expected, the average speed of the tongue movement during the closure/constriction was systematically slower for the long consonants. In addition there was a positive correlation between closure/constriction duration and the path during the closure/constriction. [Work supported by NIH.]
Reducing ambient noise in time series data with the Bartlett spectrogram
Authors: Elmore Paul , Harding Jevon
Published: October 2013

A signal processing technique for enhancing the signal-to noise ratio of transient acoustic signals is analyzed. This method subtracts the average power spectral density as calculated from the Bartlett spectrogram from the data in the frequency domain, and then forms a new time series from the resultant spectrogram and original phase information. We examine signal-to-noise ratio improvements that occur. Noisy time-series containing transient signals from synthetic data and real marine mammal recordings are used as test data sets. Results show that improvements of around 10 dB can be achieved theoretically. Limitations and pre-application considerations also are discussed.
Range-depth localization of underwater explosions by matched-field processing of data from a sparse bottom-laid horizontal array
Authors: Tollefsen Dag
Published: October 2013

Range-depth localization of underwater explosions by matched-field processing of data from a sparse bottom laid horizontal array in shallow water (the Barents Sea) has been investigated. Data from shallow (18 m) and deep (91 m) SUS charges detonated at ranges of 1–60 km endfire to a 10-element array were considered. A range-independent environment model consisting of a measured sound speed profile in water, an equivalent flat bathymetry and a two-layer fluid seabed model with geoacoustic parameters estimated by matched-field inversion of data from known sources was used. Replica fields were computed using the fast normal mode model C-SNAP. The broadband incoherent Bartlett processor was applied with data from one or two 6 Hz wide frequency bands centered within 38–94 Hz. Estimates were within ten percent from nominal in range and 15 m in depth for all shots but a few. Depth estimates for shallow sources degraded beyond a transition range; these were thereafter incorrectly estimated to be at the sea surface. Results from processing including data recorded concurrently on a vertical array (by incoherently combining data from two sections of an L-shaped array) will also be presented.
A bathymetry re-mapping technique for computing replica fields on large towed arrays
Authors: Siderius Martin , Tiemann Christopher O. , Porter Michael B.
Published: October 2013

Matched-field processing is now a well-known technique for scanning a focal spot through the ocean waveguide to localize a source. The focal spot is actually formed by intersections of surface and bottom reflected beams. It is also well known that with vertical receiver arrays bathymetry errors can cause a mirage effect in which the various reflections focus at a biased position. Typically, this bias is not a serious problem and is simply ignored. A more severe effect occurs when arrays with large horizontal aperture are used in the processing. For instance, with a large horizontal array, phones near the source see a different bathymetry than those distant from the source. In that case, using an incorrect bathymetry causes both a bias and a loss of coherence. The latter can be a very serious problem. We show that this loss of coherence can be corrected with a simple re-mapping of the phone coordinates. Through the re-mapping process we can use a flat-bottom model to rapidly predict the field on a regular grid, and then transform that replica field properly to reflect range-dependent bathymetry slices. The result is a vastly more efficient process for calculating replica fields on large, multidimensional arrays in range-dependent environments.
Forensic acoustics: An opportunity to educate
Authors: Brooks Bennett
Published: October 2013

Forensic science is narrowly defined by some as the gathering of evidence to be used in a criminal court proceeding. However, the word ‘‘forensic’’ broadly pertains to arguments made in any public forum. Those acousticians engaged in expert witness service may work in a variety of settings that address the interests of the general public. These can include quasilegal local administrative public hearings, conducted at school board or planning and zoning meetings, civil legal actions, and rarely, a criminal trial. When presenting complex scientific arguments in a public forum, the reception with which that information is met can strongly depend upon the self-interest of meeting participants, as well as the common skepticism toward all things technical. To successfully gain favor for a particular viewpoint, the target audience (board commissioners, judges, juries) must be sufficiently educated to understand the methods of acquiring valid acoustical data, and the impact of acoustics to the situation in question. The challenge is to present credible information with just enough detail to persuade, but not overwhelm, the decision maker. Illustrative case studies will be discussed.
Hot topics in acoustical oceanography
Authors: Jackson Darrell R.
Published: October 2013

Both active and passive acoustic remote sensing methods are used to measure ocean properties and processes. Observations are made on scales ranging from meters to megameters. Several techniques have recently matured from research to application. Beginning with active acoustics on megameter scales, there has been recent progress in basin-wide thermometry, and a global acoustic network has been suggested. On decimeter scales, active acoustics have been used to study hydrothermal flows occurring at oceanic ridges. The ultimate goal of the hydrothermal work is to measure fluxes of heat and particulates. Passive measurement of ambient sound in the ocean has been used successfully to observe a wide variety of processes at all scales. For passive acoustics, this talk will focus on small-scale determinations of rainfall rate and type, as well as studies of wave breaking.
Travel time estimation for ocean acoustic thermometry
Authors: Dzieciuch Matthew
Published: October 2013

The basic datum of ocean acoustic thermometry experiments is the ray travel time, thus an accurate and precise estimator is of paramount importance. It is well known that a matched filter gives the best estimate if the transmitted signal is known exactly. At basin-scale ranges, the signal becomes a random process due to the limited coherence time and coherent bandwidth of the channel. A matched filter is no longer optimum in this case, but since the reception is still partially coherent, an energy detector is not optimum either. A better estimator is the RAKE correlator, which can account for the signal variability at the cost of increased receiver complexity and a reduction of resolution. In this talk, the performance of the RAKE correlator, the matched filter, and the energy detector versus coherence time, coherent bandwidth, and SNR is explored by simulation of realistic cases. The RAKE is then applied to a 4000-km range, 75-Hz sonar transmission and the performance improvement is remarkable. An added benefit of the RAKE is that there is less clutter, or fewer false alarms in the detection theory jargon, and thus tracking an arrival over multiple transmissions is much easier.
Sound quality (SQ) of concert halls: Physical and subjective attributes
Authors: Beranek Leo L.
Published: October 2013

Each new concert hall has the following stated goal: ‘‘Acoustics equal to the best in the world.’’ The owner can specify the number of seats, areas of public spaces, lighting intensities, etc. But, the attributes of acoustical quality cannot as yet be specified. Most acoustical consultants seem to feel that a ‘‘seat of the pants’’ experience is the only possible specification. But the architect’s goal is a monument to himself and he believes the acoustical consultant should achieve the ‘‘best in the world’’ goal without visible means. Numbers for specifications are needed. In this paper 40 years of pertinent research are described: What are the critical physical attributes of good acoustics, how do we measure them, and how can they be translated into architectural specifications? Four steps have been involved: (1) interviews of conductors and music critics to determine (a) their acoustical rank orderings of a large number of halls and (b) which acoustical characteristics do they believe are important, viz., reverberance, strength of sound, etc.; (2) a determination of which physical measures correlate with their beliefs plus others that are physiologically important; (3) measurements of those physical quantities in the rank-ordered halls; and (5) the correlation of the measured values with the subjective quality ratings.
Evaluating the sound quality of reproduction systems and performance spaces
Authors: Griesinger David
Published: October 2013

Evaluation of sound reproduction systems through rapid A/B tests has led to enormous and rapid progress in system design. The sound quality of performance spaces is almost always evaluated through long term listening, and spaces are compared through remembered characteristics. Progress has not been rapid. This paper will present methods for rapid A/B comparisons of spaces and will demonstrate the results of such comparisons. The results can be very different from remembered impressions.
Research opportunities in evaluating sound system performance
Authors: Thurmond Bob
Published: October 2013

Sound reinforcement has been both ubiquitous and indispensable in our society for many years. With such a volume of experience, it would seem that the accompanying body of knowledge should be sufficient to produce a successful design for every situation. However, the quality of actual systems installed today still varies from good to terrible. A few obvious aspects of this problem have been examined, and papers published, but no serious attempt to list or organize all contributors to sound performance quality has ever been made. In addition, no evaluative techniques or analytical strategies have been established to set standards. There are several valid reasons for this. The actual performance of a sound system is surprisingly complex, both in terms of the number of factors contributing to the overall performance and in the complexity within each factor. As a result, each system is quite unique and difficult to describe in precise terms. Few rigorous investigations have been applied. The results have been meager thus far and are essentially unknown to most practitioners. Research opportunities abound, and their results could have a significant impact. In this paper the current situation is summarized and topics for future study are suggested.
Virtual acoustic prototyping
Authors: Johnson Marty
Published: October 2013

In this paper the re-creation of 3-D sound fields so the full psycho-acoustic impact of sound sources can be assessed before the manufacture of a product or environment is examined. Using head related transfer functions (HRTFs) coupled with a head tracked set of headphones the sound field at the left and right ears of a listener can be re-created for a set of sound sources. However, the HRTFs require that sources have a defined location and this is not the typical output from numerical codes which describe the sound field as a set of distributed modes. In this paper a method of creating a set of equivalent sources is described such that the standard set of HRTFs can be applied in real time. A structural-acoustic model of a cylinder driving an enclosed acoustic field will be used as an example. It will be shown that equivalent sources can be used to recreate all of the reverberation of the enclosed space. An efficient singular value decomposition technique allows the large number of sources required to be simulated in real time. An introduction to the requirements necessary for 3-D virtual prototyping using high frequency Statistical Energy Analysis models will be presented. [Work supported by AuSim and NASA.]
Origins and application of the European Union Position paper on dose response relationships between transportation noise and annoyance
Authors: Berry Bernard F.
Published: October 2013

Dose–response relationships of the sort pioneered by Schultz figure prominently in the current European noise regulation policy. A position paper developed by the Working Group on Dose-effects (part of the EU Expert Network) reviewed a range of potential health effects, but decided that annoyance and sleep disturbance remain the most prevalent and sensitive effects of transportation noise exposure, and those for which the best data were available. A Position paper providing guidance on the dose–effect relations to be used for the assessment of numbers of people annoyed by noise from transportation sources (rail, road and air) may be found at http://europa.eu.int/comm/environment/noise/home.htm This presentation explains the context in which the Paper was developed, outlines the process by which the dose–response relationships were derived and summarizes the key recommendations. Finally some observations are made as the Position Paper is being applied, and related future developments are discussed. The author acknowledges with deep gratitude the assistance of Dr. Henk Miedema of TNO in preparing this paper.
Processing and representation of social communication sounds in the brainstem auditory system of bats
Authors: Pollak George D.
Published: October 2013

While bats are best known for their abilities to orient and capture prey via echolocation, they are also highly social animals who use a rich repertoire of species-specific sounds for social communication. This talk explores how communication signals are progressively transformed and represented in the ascending auditory system. One principal transformation that distinguishes the inferior colliculus from lower nuclei is a change from processing that emphasizes response homogeneity among the neuronal population in each lower nucleus, to one that emphasizes heterogeneity and selectivity in the inferior colliculus. Collicular neurons are selective in that each neuron fails to respond to some, or even all calls, even though those calls have energy that encroaches upon their excitatory response regions, and are heterogeneous since each collicular neuron responds to a different subset of calls. The transformation from homogeneity to heterogeneity may largely be a consequence of the difference in the ways that the various excitatory and inhibitory inputs distribute along frequency contours in lower nuclei compared to the inferior colliculus. One important consequence is that those features endow the population in the inferior colliculus with the ability to respond to any signal with a unique and pronounced spatiotemporal pattern of activity. [Work supported by NIH Grant No. DC 00268.]
Do goldfish miss the fundamental?
Authors: Fay Richard R.
Published: October 2013

The perception of harmonic complexes was studied in goldfish using classical respiratory conditioning and a stimulus generalization paradigm. Groups of animals were initially conditioned to several harmonic complexes with a fundamental frequency (f0) of 100 Hz. ln some cases the f0 component was present, and in other cases, the f0 component was absent. After conditioning, animals were tested for generalization to novel harmonic complexes having different f0’s, some with f0 present and some with f0 absent. Generalization gradients always peaked at 100 Hz, indicating that the pitch value of the conditioning complexes was consistent with the f0, whether or not f0 was present in the conditioning or test complexes. Thus, goldfish do not miss the fundmental with respect to a pitch-like perceptual dimension. However, generalization gradients tended to have different skirt slopes for the f0-present and f0-absent conditioning and test stimuli. This suggests that goldfish distinguish between f0 present/absent stimuli, probably on the basis of a timbre-like perceptual dimension. These and other results demonstrate that goldfish respond to complex sounds as if they possessed perceptual dimensions similar to pitch and timbre as defined for human and other vertebrate listeners. [Work supported by NIH/NIDCD.]
Florida manatee avoidance technology: A pilot program by the Florida Fish and Wildlife Conservation Commission
Authors: Frisch Katherine , Haubold Elsa
Published: October 2013

Since 1976, approximately 25% of the annual Florida manatee (Trichechus manatus latirostris) mortality has been attributed to collisions with watercraft. In 2001, the Florida Legislature appropriated $200,000 in funds for research projects using technological solutions to directly address the problem of collisions between manatees and watercraft. The Florida Fish & Wildlife Conservation Commission initially funded seven projects for the first two fiscal years. The selected proposals were designed to explore technology that had not previously been applied to the manatee/boat collision problem and included many acoustic concepts related to voice recognition, sonar, and an alerting device to be put on boats to warn manatees. The most promising results to date are from projects employing voice-recognition techniques to identify manatee vocalizations and warn boaters of the manatees’ presence. Sonar technology, much like that used in fish finders, is promising but has met with regulatory problems regarding permitting and remains to be tested, as has the manatee-alerting device. The state of Florida found results of the initial years of funding compelling and plans to fund further manatee avoidance technology research in a continued effort to mitigate the problem of manatee/boat collisions.
Diffraction of nonlinear acoustic waves: Matched-area method
Authors: Ostrovsky Lev A.
Published: October 2013

This is a brief overview of a series of investigations undertaken by the author together with his collaborators at the Institute of Applied Physics, Russian Academy of Science. In these works, a simplified theory was developed for the acoustic waves which profile is distorted due to both nonlinearity and diffraction. The theory is based on an often existing possibility to separate the regions of nonlinear geometrical acoustics and linear diffraction and match the corresponding solutions in an intermediate area(s) where neither effect is cumulative. The problems addressed on this way include: (i) broadening of the beam pattern of an intensive acoustic radiation (with V. Fridman); (ii) behavior of a nonlinear acoustic wave near a caustic (with E. Pelinovsky and V. Fridman); (iii) radiation and focusing of nonlinear waves (with A. Sutin). In a number of cases, theoretical results were corroborated by comparison with the experimental data obtained by D. Blackstock and other researchers. This approach is believed to be an efficient tool for treating many realistic situations, and to deserve further development. This work benefited greatly from numerous contacts with Professor Blackstock, starting in the early stages of the investigation.
Neural and perceptual discrimination of the spectral and temporal modulations in birdsong and speech
Authors: Theunissen Frederic
Published: October 2013

My laboratory is interested in the neural basis of complex sound perception, including vocalizations. Our neural studies have focused on the high-level auditory system of songbirds where neurons respond preferentially to birdsong. We quantified the selectivity of these auditory neurons by recording their responses to degraded versions of song. To do so, we added noise to this natural stimulus, affecting the time-frequency structure of the sound at different scales. We found that at particular time-frequency scales the noise has little effect on the response of the neurons, while at other scales it greatly reduces the neural response. We correlated the tuning of the neurons with the statistical structure in the birdsongs that allows the discrimination of songs produced by different birds. We found a good match between the optimal scale of the neurons sensitivity curve and the scale that best captures the variance in the acoustical structure of an ensemble of songs. We have done a similar analysis with speech, where the neural tuning curve in songbirds is replaced by a human perceptual tuning curve based on speech intelligibility. As in songbirds, the scale for optimal speech perception is also best for capturing the statistical structure in the speech signal.
Audio signal recognition for speech, music, and environmental sounds
Authors: Ellis Daniel P. W.
Published: October 2013

Human listeners are very good at all kinds of sound detection and identification tasks, from understanding heavily accented speech to noticing a ringing phone underneath music playing at full blast. Efforts to duplicate these abilities on computer have been particularly intense in the area of speech recognition, and it is instructive to review which approaches have proved most powerful, and which major problems still remain. The features and models developed for speech have found applications in other audio recognition tasks, including musical signal analysis, and the problems of analyzing the general ‘‘ambient’’ audio that might be encountered by an auditorily endowed robot. This talk will briefly review statistical pattern recognition for audio signals, giving examples in several of these domains. Particular emphasis will be given to common aspects and lessons learned.
Superdirective and gradient sensor arrays
Authors: Merklinger Harold M.
Published: October 2013

During the late 1960s and the 1970s, underwater acoustic investigators examined superdirective and gradient sensor systems in order to enhance submarine detection capabilities for surface ships and maritime aircraft. Simple gradient processing had already been used in both in-air acoustic systems (cardioid and super-cardioid microphones) as well as radio and radar applications. Superdirective techniques were known [R. L. Pritchard, J. Acoust. Soc. Am. 25, 879 (1953)] and sometimes exploited in radar systems. It was quickly demonstrated that simple gradient sensors and modest degrees of superdirective array processing were possible, although self-noise and the ability to calibrate hydrophones limited the processing gains achievable. Circular superdirective arrays were used extensively by the Defence Research Establishment Atlantic for noise directionality measurements in the frequency range 4 Hz to about 1 kHz and considered for naval ASW applications until the superiority of oil-filled conventional arrays became apparent. Nevertheless, the significant theoretical and practical development of spatial harmonic beamforming and direction finding was completed. Although much of this work was not considered classified, neither was it widely published. This presentation will review the concepts developed and progress made. Beamforming, noise mitigation and calibration issues are covered.
Experimental performance analysis of a superdirective line array
Authors: Humphrey Victor F. , Hines Paul C. , Young Victor
Published: October 2013

Superdirective line arrays can provide a significant array gain from a structure that is relatively small in terms of acoustic wavelengths. However, system imperfections, electronic noise and acoustic scatter from the array structure can degrade their performance. An acoustic calibration of a six-element line array, 0.8 m in length, has been performed over the frequency range 1 to 4 kHz in order to investigate the performance of a real array. The data is used to identify the angular variation of the hydrophone outputs and the phase difference between hydrophone pairs. These angular responses are analyzed in terms of a modal series in order to quantify the variations and help identify the source of perturbations. The effects of imperfections are also investigated by synthesising superdirective arrays of order 1 to 5 and monitoring how the array gain varies for both deterministic signals and ambient acoustic noise. These results are compared with theoretical predictions. Further evidence of the variation in performance is gained by comparing the output of different implementations of lower order arrays, synthesized from subsets of the full array. The results indicate the influences that the array structure may have on the performance of the array.
Analysis of measured broadband acoustic propagation using a parabolic equation approach
Authors: Gray Mason , Knobles D. P. , Koch Robert
Published: October 2013

A broadband parabolic equation (PE) approach is employed to simulate data taken from two Shallow Water Acoustic Measurement Instrument (SWAMI) bottom mounted horizontal line array (HLA) experiments in shallow water environments off the east coast of the U.S. and in the Gulf of Mexico. In both experiments the HLA was deployed along an isobath. Light bulbs were imploded at known depths and ranges in both the range-independent (array end fire) and range-dependent (array broadside) directions. For the east coast experimental data, the PE model is used to infer a seabed geoacoustic description in both the range-dependent and range-independent directions. Also, comparisons of modeled time series were made for the range-independent case with a broadband normal mode model to validate the PE calculations. In the Gulf of Mexico experiment, the sediment geoacoustic profile is well known from previous inversions and geophysical measurements. This known seabed description was used to simulate the range-dependent data. A broadband energy-conserving coupled mode approach is also employed to model the range-dependent propagation. This allows the physical mechanisms associated with range-dependent propagation to be examined in a quantitative manner for this shallow water environment. [Work supported by ONR.]
Nonlinear modes interaction in an acoustic waveguide
Authors: Castor Kaelig , Roux Philippe , Kuperman W. A. , McDonald B. E.
Published: October 2013

The nonlinear interaction of lower order modes in an acoustic waveguide is investigated. For finite-amplitude wave propagation, nonlinear effects redistribute the modal amplitudes as a function across frequency and wave number. Therefore, the nonlinear propagation in a waveguide can produce an arrival structure quite different from the classical result. Simulations with the NPE code [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406–1417 (1987)] were used to study this frequency mode coupling in a realistic ocean waveguide.
Modeling mid-to-high frequency acoustic signal fluctuations induced by fetch limited sea surface roughness in shallow water
Authors: Heitsenrether Robert , Badiey Mohsen
Published: October 2013

Surface waves are among several environmental parameters that significantly influence mid-to-high frequency (1–18 kHz) acoustic wave propagation. In coastal regions, surface waves are fetch limited with reduced spectral level at lower frequencies. In order to assess the detail of an acoustic signal interaction with the sea surface in such regions, a combined approach based on experimental observation and modeling of both surface waves and acoustic waves has been adopted. Data from two broadband shallow water acoustic experiments are presented. These data include simultaneous wind speed and acoustic propagation measurements. The experimental design allowed an examination of received signals corresponding to single surface bounced ray paths. Measured data analysis shows a high correlation between time–angle–intensity fluctuations of received signals and varying sea surface conditions. An empirical fetch-limited ocean wave spectrum has been combined with an acoustic ray-based model to study acoustic wave propagation. Rough sea surface realizations are generated and used as sea surface boundaries with the acoustic model. This combined sea surface/acoustic model predicts the variability of acoustic signal fluctuations as a function of varying sea surface. Modeled time–angle–intensity signal fluctuations compare excellently with field data at lower wind speeds.
Narrowband signals propagation in randomly inhomogeneous shallow water waveguide
Authors: Katsnelson Boris , Pereselkov Sergey , Petnikov Valery
Published: October 2013

In the presented work results of experiment and theoretical modeling are considered for the narrowband (ratio of frequency band to frequency ∼0.1) sound propagation at the long range (up to 200 km) acoustic track in Barents sea. Modes selection for these conditions can be used for acoustical tomography of large-scale perturbations. Characteristics of the sound signals passing through this area (and in turn feasibility of tomographic methods) are determined by mutually competing mechanisms: waveguide dispersion, providing modes filtering, modes attenuation and modes coupling due to random inhomogeneities, masking separation of modes. Experimental results presented in this work show significant influence of noise (or modes coupling). For interpretation of experimental results (frequency and time dependencies of arriving pulses) background internal waves are taken as a main reason of the modes coupling. It is shown that for the modes separation it is necessary to use vertical array along with the measuring difference in arrival time, and correlation processing of received signals. [Work supported by RFBR, grants Nos. 03-05-64568 and 02-02-16509.]
Acoustical considerations for secondary uses of government facilities
Authors: Evans Jack B.
Published: October 2013

Government buildings are by their nature, public and multi-functional. Whether in meetings, presentations, documentation processing, work instructions or dispatch, speech communications are critical. Full-time occupancy facilities may require sleep or rest areas adjacent to active spaces. Rooms designed for some other primary use may be used for public assembly, receptions or meetings. In addition, environmental noise impacts to the building or from the building should be considered, especially where adjacent to hospitals, hotels, apartments or other urban sensitive land uses. Acoustical criteria and design parameters for reverberation, background noise and sound isolation should enhance speech intelligibility and privacy. This presentation looks at unusual spaces and unexpected uses of spaces with regard to room acoustics and noise control. Examples of various spaces will be discussed, including an atrium used for reception and assembly, multi-jurisdictional (911) emergency control center, frequent or long-duration use of emergency generators, renovations of historically significant buildings, and the juxtaposition of acoustically incompatible functions. Brief case histories of acoustical requirements, constraints and design solutions will be presented, including acoustical measurements, plan illustrations and photographs. Acoustical criteria for secondary functional uses of spaces will be proposed.
Multimodal imaging of the human temporal bone: A comparison of CT and optical scanning techniques
Authors: Voie Arne H. , Whiting Bruce , Skinner Margaret , Neely J. Gail , Lee Kenneth , Holden Tim , Brunsden Barry
Published: October 2013

A collaborative effort between Washington University in St. Louis and Spencer Technologies in Seattle, WA has been undertaken to create a multimodal 3D reconstruction of the human cochlea and vestibular system. The goal of this project is to improve the accuracy of in vivo CT reconstructions of implanted cochleae, and to expand the knowledge of high-resolution anatomical detail provided by orthogonal-plane optical sectioning (OPFOS). At WUSL, computed tomography (CT) images of the cochlea are used to determine the position of cochlear implant electrodes relative to target auditory neurons. The cochlear implant position is determined using pre- and post-operative CT scans. The CT volumes are cross-registered to align the semicircular canals and internal auditory canal, which have a unique configuration in 3-D space. The head of a human body donor was scanned with a clinical CT device, after which the temporal bones were removed, fixed in formalin and trimmed prior to scanning with a laboratory Micro CT scanner. Following CT, the temporal bones were sent to the OPFOS Imaging Lab at Spencer Technologies for a further analysis. 3-D reconstructions of CT and OPFOS imaging modalities were compared, and results are presented. [Work supported by NIDCD Grants R44-03623-5 and R01-00581-13.]
Functional brain imaging and bioacoustics in the Bottlenose dolphins, Tursiops truncatus
Authors: Ridgway Sam , Finneran James , Carder Donald , Van Bonn William , Smith Cynthia , Houser Dorian , Mattrey Robert , Hoh Carl
Published: October 2013

The dolphin brain is the central processing computer for a complex and effective underwater echolocation and communication system. Until now, it has not been possible to study or diagnose disorders of the dolphin brain employing modern functional imaging methods like those used in human medicine. Our most recent studies employ established methods such as behavioral tasks, physiological observations, and computed tomography (CT) and, for the first time, single photon emission computed tomography (SPECT), and positron emission tomography (PET). Trained dolphins slide out of their enclosure on to a mat and are transported by trainers and veterinarians to the laboratory for injection of a ligand. Following ligand injection, brief experiments include trained vocal responses to acoustic, visual, or tactile stimuli. We have used the ligand technetium (Tc-99m) biscisate (Neurolite) to image circulatory flow by SPECT. Fluro-deoxy-d-glucose (18-F-FDG) has been employed to image brain metabolism with PET. Veterinarians carefully monitored dolphins during and after the procedure. Through these methods, we have demonstrated that functional imaging can be employed safely and productively with dolphins to obtain valuable information on brain structure and function for medical and research purposes. Hemispheric differences and variations in flow and metabolism in different brain areas will be shown.
Physics of tissue harmonic imaging
Authors: Szabo Thomas L.
Published: October 2013

Tissue harmonic imaging is used on almost all modern diagnostic ultrasound equipment. The clinical success of this modality involves a combination of fortuitous factors. The improvement in lateral resolution obtained by transmitting on a fundamental frequency and receiving on a harmonic is well known. Other advantages include a deeper focal range with less absorption than would have been obtained by transmitting and receiving at twice the fundamental frequency. Natural apodization considerably reduces the 3-D volume of interaction with tissue. Simulations indicate that harmonic imaging is more robust in the presence of aberration. Analysis shows that the improvements over what would have been achieved by transmitting at twice the frequency are for shallower focal depths. Reasons for the noticeably enhanced contrast of harmonic imaging are discussed.
Physics of the violin
Authors: Jansson Erik V.
Published: October 2013

A method to measure acoustical properties of the violin has been developed. The bridge is excited by an impulse force hammer (see www.speech.kth.se/music/acviguit4). Bridge vibrations are recorded by a small magnet and an electrical coil. Measurements can be made in an ordinary room and give a record of properties built into the violin body. An old good Polish violin, B Dankwart, Vilnius ca. 1600 shows typical results with peaks P1, P2 and the BH-hill. Our goal is as suggested by Gabriel Weinreich ‘‘to understand, not to copy,’’—Stradivarius. By shifting the soundpost position the peaks P1, P2 and BH can be somewhat monitored. It can be shown that the BH is not confined to the bridge only. The feet distance of the bridge is important but also the top plate. Marcin Groblicz, the great Polish violin maker, was court instrument maker in Krakow ca. 1600 to Sigismund, King of Poland and Sweden. I believe Gabriel Weinreich has some connection to Vilnius in Poland but unfortunately not to Sweden. We like Gabi.