bluuebunny/crossref_metadata_2025 huggingface dataset:
Reverberation versus time or reverberation versus range? A definitive relationship.
Authors: Harrison Chris
Published: October 2009

Strictly reverberation consists of all the back-scattered contributions from many locations that arrive at one absolute time regardless of their respective travel times. However, for calculation purposes, particularly at long range, it is often more convenient to assume the scatterers to be close together at a single location with corresponding propagation loss for the outward and return paths. It would be useful to know whether the latter approximation is a safe one or not. An analytical method of calculating reverberation either at a fixed time or at a fixed range will be presented. The ratio of these quantities is found to depend on the (vertical) angular spread of the contributing paths. In isovelocity water at long ranges, mode-stripping reduces the angular spread to the point where fixed-range reverberation is indistinguishable from fixed-time. The greatest effect is at shorter ranges where there is no significant mode-stripping, and the ratio rises to roughly 1 plus 0.855 times the square of the critical angle (in radians). Thus the effect is typically less than 1 dB at any range.
Real-time Renyi entropy processing for molecular imaging using targeted nanoparticles.
Authors: Wallace Kirk , McCarthy John , Wickerhauser Victor , Marsh Jon , Lanza Gregory , Wickline Samuel , Hughes Michael
Published: October 2009

Previously, improvements in in vivo molecular imaging sensitivity were obtained using Renyi entropy, If(r) with values of r near 2, specifically r=1.99. This result raised the possibility of further improvements in sensitivity even closer to the limit r→2 [at r=2, If(r) is undefined]. However, such an investigation was not feasible due to excessive computational time required to calculate If(r) near this limit. In this study, an asymptotic expression for the limiting behavior of If(r) as r→2 is derived and used to present results analogous to those obtained with If(1.99). Moreover, the limiting form, If,∞ is computable directly from the experimentally measured waveform, f(t) by an algorithm suitable for real-time implementation. To test our approach, five mice were injected with αυβ3-targeted nanoparticles, and ultrasound images obtained at 0-, 15-, 30-, and 45-min post-injection. Two control groups (N=5, injected with untargeted-nanoparticles, or no injection) were also imaged. Renyi images were able to differentiate the groups (p<0.05) at 15 min post-injection. This outcome agrees with previous studies using targeted-nanoparticles and demonstrates the ability of entropy-based signal receivers when used in conjunction with targeted-nanoparticles to elucidate the presence of αυβ3-integrins in primordial neovasculature, particularly in acoustically unfavorable environments. [Work supported by NIH EB002168.]
Influence of accordion reed chamber geometry on reed vibration and airflow.
Authors: Coyle Whitney L. , Behrens Sarah L. , Cottingham James P.
Published: October 2009

An experimental study has been made on the motion of air-driven accordion reeds in which some measurements were made with the reed block removed from the instrument, but most were made with the reeds in the instrument with the bellows replaced by a clear acrylic wind chest driven at appropriate blowing pressure by a small organ blower. Measurements of reed displacement and velocity as a function of time were made using a laser vibrometer system, and corresponding sound pressure waveforms were obtained from a probe microphone near the reed opening. Airflow waveforms were calculated by integrating the pressure waveform and using a computed area function. Effects of changes in reed chamber geometry on the reed vibration spectrum and the airflow waveform have been investigated, along with effects on the spectrum of the radiated sound and sounding frequency. Results of changes in the position of the pallet valve, such as partial opening, have also been studied. Additional measurements made for each reed include the variation in sounding frequency and amplitude of vibration with blowing pressure. The results are compared with previous measurements and calculations from theoretical models. [Work partially supported by National Science Foundation REU Grant No. PHY-0354058.]
Controlling ball mill noise with acoustic blankets: A case study.
Authors: Zuchelli David R
Published: October 2009

The purpose of wrapping ball mills with thermal/acoustic blankets is twofold: (1) to maintain the desired temperature inside the mill and (2) to reduce the sound emanating from the mill. This field case study focuses solely on the latter, evaluating and documenting the sound level reduction attributed to the installation of the blankets and its potential to reduce the noise dose experienced by the process attendant. One of the three ball mills had already been treated (baseline) before the evaluation started. However, treating the remaining two mills still proved to be very effective, further reducing ball mill noise in the near field by as much as 10.0 dBA and producing far field noise reductions of 3.0 dBA or greater, extending as far as 35 ft from the mills and to the floor above. The model developed from the survey data shows that a process attendant spending a substantial portion of a shift in the mill building will experience a significant reduction in overall nose dose.
In-situ measures of user’s preferred listening levels with a portable digital music device.
Authors: Goshorn Edward L. , White Kathryn J. , Kemker Brett E.
Published: October 2009

The recent development and popular use of personally worn digital music devices (PDMDs) have led to concerns about the intensity levels they produce. There is concern that users will set a PDMD to levels that are known to be hazardous to human hearing. The concern stems from the private nature of a PDMD in that insert earphones are worn that restrict the output to the user’s ears, thus prohibiting monitoring of such devices by parents, teachers, employers, etc. This project measured the in-situ dB SPL produced by PDMDs worn by 31 young adults (18–23 years) who had been wearing PDMDs for 3 years or less. Subjects set their PDMD to their preferred listening level (PLL) for a popular tune. Once set, in-situ SPL measures of the tune at a reference point and then for a white noise were obtained with a probe microphone located near the eardrum. Hearing thresholds were also obtained. Results showed a range of 52–107 dB with a mean PLL of 83 dB for music and a range of 53–99 dB with a mean PLL of 79 dB for white noise. None of the subjects had significant hearing loss.
Automated extraction of prosodic features and analysis for emotional states.
Authors: Lee Suk-Myung , Choi Jeung-Yoon
Published: October 2009

This study investigated the relationship between emotional states and prosody. A prosody detection algorithm [Choi et al., J. Acous. Soc. Am. 188, 2579–2587] was applied to extract accents and intonational boundaries automatically. The measurements used are derived from duration, pitch, harmonic structure, spectral tilt, and amplitude. Detection experiments on the Boston University Radio Speech Corpus show equal error detection rates around 70% for accent and intonational boundary detection. This algorithm was applied to a Korean emotional database subset, in which five sentences were spoken by 15 speakers over four emotions: neutral, joy, sadness, and anger. By comparing the ratio of events that were detected as accent and intonational boundaries between neutral speech and emotional speech, our experiments find different distributions of these events for each emotion. In preliminary experiments, joy and anger tended to have fewer events classified as boundaries compared to other emotions. Also, joy and sadness have more events corresponding to accents. These results indicate that prosody detection can be useful for classification of emotion.
Effects of altered sensorimotor function of the tongue on spectral characteristics of sibilants /s, z/.
Authors: Laaksonen Juha-Pertti , Rieger Jana , Harris Jeffrey , Seikaly Hadi
Published: October 2009

Acoustic characteristics of sibilant sounds produced by 17 Canadian English-speaking female (6 patients) and male (11 patients) tongue cancer patients were studied. The patients had undergone a tongue resection of the anterior 2/3 of the tongue, and tongue reconstruction with a radial forearm free flap (RFFF). The acoustic data included measurements of the spectral moments (mean, standard deviation, skewness, and kurtosis) of sibilants /s, z/ analyzed from speech samples (stimulus sentences and Zoo Passage) which were recorded before the tongue resection, and 1 month, 6 months, and 12 months after the resection with RFFF reconstruction. Primarily, the tongue reconstruction with RFFF was found to result in temporary changes on the spectral characteristics such that speech output was found to approach the pre-operative speech quality over the 1-year period. In addition, RFFF reconstruction of the tongue was found to have some gender-specific effects in the acoustic characteristics analyzed. However, there was variability between patients, indicating individual compensatory and adaptive mechanisms for the altered sensorimotor function of the tongue following tongue reconstruction with RFFF. [The protocol for this study has been approved by the Health Research Ethics Board (HREB) of the University of Alberta (Edmonton, AB, Canada).]
Modeling and observations of coherent effects in reverberation from the Clutter09 cruise.
Authors: LePage Kevin D.
Published: October 2009

Reverberation is often assumed to be a process which decorrelates multipath, leading to the use of intensity models which ignore coherent interactions. In this talk experimental evidence of coherent effects in reverberation are demonstrated from data obtained during the Clutter09 cruise in the Straits of Sicily conducted by NURC, and the ephemeral nature of these effects is discussed. The theoretical basis for coherence between reverberation multipaths is described for both rough surface and volume scattering, including the theoretical basis and conditions for the appearance and characteristics of striations in the reverberation spectrograms.
Studying architectural acoustics through the University of Nebraska’s Architectural Engineering Program.
Authors: Wang Lily M. , Lau Siu-Kit
Published: October 2009

Architectural engineering (AE) is a discipline of study that is only currently available at 17 schools across the United States, and even fewer of these AE programs include acoustics as a main option in their curricula. This presentation will review the Nebraska Acoustics Group, housed within the AE Program at the University of Nebraska which began in 1998. Students may study acoustics within any of our five engineering degree programs (BSAE, MAE, MEng, MS and Ph.D.). Currently there are two AE faculties out of 11 who focus in acoustics at Nebraska, and the program regularly offers at least six recurring acoustics courses. Descriptions of the acoustics courses, the research interests of the Nebraska Acoustics Group, and where our graduates are to date will be given. Specifically highlighted will be the theme of our acoustics group: to promote the advancement and science of architectural acoustics by closely tying our coursework and research to practice in the “real-world.”
Taming the Jez monster: Estimating fin whale spatial density using acoustic propagation modeling.
Authors: Mellinger David K. , Küsel Elizabeth T. , Thomas Len , Marques Tiago A.
Published: October 2009

The spatial density of calling animals may be estimated acoustically using methods presented by Buckland et al. [Advanced Distance Sampling (Oxford University Press; Oxford, 2004)]; information on the call (or other cue) rate, the call detection probability as a function of range, and the probability of a false detection to obtain an estimate of spatial density. Here we use similar methods to estimate the density of calling fin whales (Balaenoptera physalus) from the level of received sound near 20 Hz—the so-called “Jez monster.” Using published source levels and call rates of fin whales, a Monte Carlo method is developed that simulates a given spatial density of whales randomly situated around a hydrophone and uses acoustic propagation modeling (specifically, a parabolic equation model) to estimate the resulting level of received sound. Using this technique at several deep-water sites in the North Atlantic, we derive a function that maps loudness to spatial density, and then use this function to estimate spatial density at these locations.
Phase and amplitude monopulse techniques to increase the accuracy of within-beam bearing estimates of volume scatterers.
Authors: Brogan Daniel S. , Chamberlin Kent A.
Published: October 2009

Traditionally, designers of multibeam sonars have limited the accuracy of echo angle-of-arrival (bearing) estimates by mapping each measured echo to its beam’s maximum response axis. Although this bearing accuracy can be improved for large targets, e.g., the ocean floor, by applying filtering techniques to the time series of bearing estimates, the echoes from water column scatterers are often only a few time samples in duration. Therefore, it is beneficial to both increase the quantity and improve the accuracy of these few echo bearing estimates. Phase and amplitude monopulse techniques use linear mappings between the sine of the echo bearing and (1) the differential signal phase and (2) the natural logarithm of the ratio of the signal magnitudes, respectively, of neighboring beams to provide within-beam echo bearing estimates. Using either of these techniques, the accuracy of the bearing estimates of the echo’s acoustic center is improved compared to maximum-response-axis mapping. By using both techniques simultaneously, the effective number of echo bearing estimates is doubled. These techniques are applicable to both planar and cylindrical multibeam sonar systems.
Geoacoustic inversion using specific acoustic impedance.
Authors: Crocker Steven E. , Miller James H. , Smith Kevin B. , Hines Paul C. , Osler John C.
Published: October 2009

An inversion method for the estimation of geoacoustic properties of the ocean bottom using data from a small number of acoustic vector sensors was developed. The experimental data used for the inversions were short duration, gated continuous wave transmissions acquired on four acoustic vector sensors that spanned the water-sediment interface during the Sediment Acoustics Experiment 2004 (SAX04) conducted in the Gulf of Mexico. The acoustic signals were analyzed for their specific acoustic impedance over a bandwidth ranging from 600 to 2400 Hz. The specific acoustic impedance was obtained from simultaneous measurements of the acoustic pressure and particle acceleration for arrivals at normal incidence. A differential evolution algorithm was used for the inversion of the depth dependent sediment properties. A wave number integration routine was used to compute the specific acoustic impedance corresponding to the estimated sediment parameters. Experiment details, forward modeling, inversion methods, and results are discussed. [Work supported by ONR.]
Perception strategies for violin sounds.
Authors: Bader Rolf
Published: October 2009

Subjects use different perception strategies when listening to violin tones coming from realistic and from unrealistic violin geometries. The perception of realistic-geometry violin top plate tones is based on pattern recognition using multiple sound features. In a multidimensional scaling method, experiment subjects were able to linearly sort sounds according to linear geometric changes of the violin top plate only as long as the geometry was within realistic limits. Here learned sound features of brightness of different spectral bands were detected and clearly associated with features of the violin geometry. When unrealistic-geometry sounds were presented, the perception strategy changed and only relations between single spectral bands and perceived sound similarities could be observed. In a second experiment, the back plate was investigated likewise where no pattern recognition could be found, because the back plate is radiating much less and so the overall violin timbre known to subjects is the top rather than the back plate one. The sounds were produced by a whole body computer physical model simulation, where the violin top and back plates were changed in thickness within the range 1–3 mm in steps of 0.25 mm playing a virtual open e-string.
Nanoparticle-targeted photoacoustic cavitation for deep tissue optical imaging.
Authors: McLaughlan James R. , Roy Ronald A. , Murray Todd W.
Published: October 2009

Photoacoustic tomography is a non-invasive imaging technique based on broadband acoustic emissions from light absorption in tissue. Light-absorbing gold nanoparticles can be introduced and targeted to specific cell populations, thereby promoting both contrast and the ability to delineate tissue types. For sufficiently high laser fluence, a transient vapor cavity is formed and undergoes inertial collapse, generating enhanced emission and additional contrast. However, the fluence required to achieve this effect usually exceeds the maximum permissible exposure for tissue. By combining ultrasonic and optical pulses, the light and sound thresholds required to repeatedly generate inertial cavitation were reduced to 5 mJ/cm2 and 1 MPa, respectively. Experiments employed a transparent arylimide gel possessing a small (<600 μm) region doped with 80nm diameter gold nanoparticles and simultaneously exposed to pulsed laser light (532 nm) and pulsed ultrasound (1.1 MHz). The amplitude of broadband emissions induced by both light and sound exceeded that produced by light alone by almost two orders of magnitude, thereby facilitating imaging a deeper depth within tissue. Two-dimensional images of doped regions generated from conventional photoacoustic and ultrasound-enhanced emissions are presented and compared. Implications for imaging and HIFU therapy are discussed. [Work is supported by a Boston University Dean’s Catalyst Award.]
The use of the photoacoustic effect for non-invasive temperature monitoring during high intensity focused ultrasound exposures.
Authors: McLaughlan James R. , Chitnis Parag V. , Mamou Jonathan , Murray Todd W. , Roy Ronald A.
Published: October 2009

High intensity focused ultrasound (HIFU) is a non-invasive technique for treating soft tissue tumors. A feasibility study for using the photoacoustic (PA) effect to monitor in-situ temperature changes during HIFU exposures is presented. A PA wave is generated from the thermoelastic expansion of a light-absorbing medium with its amplitude related to the Grüneisen parameter of the medium, which, for water, depends linearly on temperature. A 2-MHz HIFU transducer heated a cylindrical graphite inclusion in which a wire thermocouple was embedded. A 532-nm pulsed laser illuminated the inclusion at a rate of 10 Hz, and a 15-MHz passive transducer monitored the PA response throughout the 30-s exposure. Singular-value-decomposition analysis of the PA response was performed to extract the contribution from temperature change. Thermocouple measurements indicated a temperature increase from 22–60 °C, depending on the HIFU intensity employed, with a concomitant 20%–30% increase in PA amplitude. PA-based temperature curves correlated with the thermocouple measurements (rms deviation <5 °C). This technique tracked both the heating and cooling phases of the HIFU exposure and potentially could be used to noninvasively monitor in-situ temperature in real-time during HIFU. [Work supported by a Boston University Dean’s Catalyst Award and the RRI’s Biomedical Engineering Research Fund.]
Factors affecting a loudness asymmetry in real-room reverberation.
Authors: Raimond A. , Watkins A. J.
Published: October 2009

Narrowband stimuli with envelopes that have a slow-attack and a fast-decay (S-F) are judged to be louder than temporally-reversed, equal-energy versions of the stimuli (i.e., fast-attack and slow-decay, or F-S). We have found that this perceived loudness asymmetry is also apparent with real-room reflection patterns using dichotic presentation of sounds processed with binaural room impulse responses. These findings are consistent with the idea that the energy in the decaying tails of stimuli is discounted from loudness judgments because they are perceptually attributed to room reverberation. These results might therefore arise from the same perceptual mechanism that compensates for reverberation in speech which seems to operate within but not between frequency bands. Here, we ask whether the loudness asymmetry is similarly a “band-by-band” mechanism using conditions where loudness comparisons are made between S-F and F-S stimuli that are in the same or in different frequency bands.
Modeling the sensory distributions and decision space of frequency-discrimination tasks with deviant stimuli.
Authors: Espinoza-Varas Blas
Published: October 2009

Discrimination tasks with deviant stimuli are used often in electrophysiological studies of selective auditory attention [e.g., Rinne et al., Brain Res. 1077, 135–143 (2006)]; for example, participants may be asked to discriminate between complex tones differing in fundamental frequency (186 versus 196 Hz). Presentation probability is high (e.g., 0.82) for fixed level (e.g., 60-dB SL) standard stimuli and low (e.g., 0.18) for deviant stimuli that are 3–9 dB higher or 3–9 dB lower than the standard. Since the level differences are irrelevant to the frequency-discrimination task, the longer response time and higher error rate of deviant versus standard stimuli may be interpreted in terms of distraction caused by deviance. In this study, the sensory effects of standard and deviant stimuli were modeled in terms of two-dimension (frequency by level) probability distributions with densities proportional to presentation probability. It was assumed that the perceptual dimensions (pitch and loudness) are partly correlated, and that perceptual decisions are based on a decision criterion controlled mainly by the standard frequency difference. The model suggests that, in addition to distraction, other factors could also account for deviance effects.
Pressure and displacement fields inside an absorbing fluid sphere ensonified by a point acoustic source: comparison of analytic and numerical solutions.
Authors: Foote Kenneth G. , Francis David T. I. , Zampolli Mario
Published: October 2009

The interaction of an external point acoustic source in a lossy immersion medium with an absorbing fluid sphere is modeled. The analytic boundary-element-method and finite-element-method solutions for the internal pressure and displacement fields are evaluated numerically for a 50-mm-diameter fluid sphere in an immersion medium of mass density of 1000 kg/m3 and sound speed of 1500 m/s. The mass density and sound speed of the fluid sphere are treated as parameters varying from 0.5 to 2 times the value of the corresponding medium property. Absorption is neglected in the immersion medium but is assumed to be 0 or 10 dB per wavelength in the fluid sphere. Each of two frequencies is considered, 10 and 100 kHz, for which the approximate wavenumber-radius products are 1 and 10, respectively. Results for the three solution methods are compared. [Work partly supported by NOPP through ONR Award No. N000140710992.]
Experimental demonstration of geoacoustic tracking using particle filters.
Authors: Yardim Caglar
Published: October 2009

This paper discusses practical aspects and performance of particle filters in geoacoustic inversion using data from the MAPEX experiment north of Elba Island, Italy in 2000. The particle filter enables spatial and temporal tracking of environmental parameters and their underlying probability densities, making geoacoustic tracking a natural extension to geoacoustic inversion techniques. The setup includes a ship-towed horizontal line array and a moored, broadband acoustic source in a shallow water environment. The ship track includes two sharp turns that cause bending of the array. The particle filter is used to track the ship parameters (range, bearing, and speed), array parameters (tilt and bow), and environmental parameters (water depth and sediment sound speed). The filter performance is discussed for both the fast turns and the straight, constant velocity sections of the ship track. The results are compared with the inversion results obtained using genetic algorithms. [Work supported by ONR.]
Bayesian tracking predictions in an uncertain ocean environment.
Authors: Dosso Stan E. , Wilmut Michael J.
Published: October 2009

This paper considers probabilistic prediction of the future locations of a moving acoustic source in the ocean based on past locations as determined by Bayesian source tracking in an uncertain environment. The Bayesian tracking approach considers both source and environmental parameters as unknown random variables constrained by noisy acoustic data and prior information and numerically integrates the posterior probability density (PPD) over the environmental parameters to obtain a time-ordered sequence of joint marginal probability surfaces over source range and depth. The integration is carried out using Markov-chain Monte Carlo sampling methods which provide a large collection of track realizations drawn from the PPD. Applying a probabilistic model for source motion to each of these realizations produces a sequence of source range-depth probability distributions for future times. These predictions account for both the uncertainty of the source-motion model and the uncertainty in the state of knowledge of past source locations, which is itself dependent on environmental uncertainty. Several source-motion models, which differ in the degree of confidence assigned to future predictions based on past locations, are considered for range-depth tracking and prediction using a vertical sensor array.
Comparison and analysis of equalization techniques for the time-varying underwater acoustic channel.
Authors: Blair Ballard J. S. , Preisig James C.
Published: October 2009

It has long been accepted that adapting a decision feedback equalizer in a time-varying environment by first estimating the channel impulse response and using this estimate to calculate equalizer tap coefficients results in better performance than is achieved by directly adjusting the equalizer taps. There are several empirical demonstrations in the literature, [Shukla and Turner, IEE Proc.-Commun. 138, 525–543 (1991)], but the explanations for the performance difference are varied and none uses analytical arguments. Analysis shows that at high signal-to-noise ratio (SNR) for time varying channels, the taps of the feed-forward equalizer fluctuate more rapidly than do the taps of the channel impulse response and using channel estimate based adaptation is more effective. The largest changes in the equalizer coefficients occur when the input signal correlation matrix has a large condition number. At low SNR the matrix is better conditioned and the performance gap disappears. These results assume that the delay spread of the channel impulse response can be correctly estimated. When this is not the case, directly adapting the equalizer coefficients results in better performance than is achieved using the channel estimate based approach. [Work supported by ONR Grant Nos. N00014-05-10085 and N00014-07-10184.]
Use of within-beam mapping in conjunction with Kalman filtering to improve angle of arrival estimation accuracy in multibeam echo-sounding.
Authors: Brogan Daniel S. , Chamberlin Kent A.
Published: October 2009

The positions of both water column scatterers and the ocean floor can be estimated using data from multibeam sonars. In a previous presentation [D. S. Brogan and C. P. de Moustier, J. Acoust. Soc. Am. 119, 3352 (2006)] it was shown that a Kalman filter could be used to track echo angles of arrival (bearings) versus time for such targets using quadrature-sampled multibeam sonar data. In that research, the inputs to the Kalman filter were the echo magnitude time series of each beam placed on that beam’s maximum response axis. While the results using this approach proved to be superior to those of a conventional split-aperture processor, the bearing accuracy can be further improved by applying a pre-processing stage that maps each echo to its acoustic center rather than to its beam’s maximum response axis. This mapping is accomplished using phase and/or amplitude monopulse techniques that provide linear mappings between the sine of the echo bearing and (1) the differential signal phase and (2) the natural logarithm of the ratio of the signal magnitudes, respectively, of neighboring beams to provide within-beam echo bearing estimates. Results are compared both with and without the pre-processing stage.
Frequency domain tracking of passive vessel harmonics.
Authors: Ogden George , Zurk Lisa , Siderius Martin , Sorensen Eric , Meyers Josh , Matzner Shari , Jones Mark
Published: October 2009

This paper presents a method for passive acoustic detection and tracking of small vessels in noisy, shallow water marine environments. Passive spectra of boats include broadband noise as well as tones that are harmonics of the engine speed and shaft/propeller rotation. Past work suggests that the location in frequency and the relative amplitudes of these harmonics can be used to determine specific characteristics of the vessel such as the number of blades on the propeller and engine type/speed. However, the low signal to noise ratio of quiet targets and Doppler shifts incurred because of source and receiver motion complicate the identification of these tones in the lofargram. To address this issue, a combined detection and tracking approach is proposed in which intermittent and wandering harmonic content is tracked with a multi-dimensional Kalman filter. Results from recorded passive signatures from several classes of vessels in marine and freshwater environments in the Pacific Northwest are presented and discussed.
Temporal and spatial coherences of sound at 250 Hz and 1659 km in the Pacific ocean: Demonstrating deterministic effects and internal waves explain observations.
Authors: Spiesberger John
Published: October 2009

The hypothesis tested is that internal gravity waves explain temporal and spatial coherences of sound at 1659 km in the Pacific ocean for a signal at 250 Hz and a pulse resolution of 0.02 s. From data collected with a towed array, the measured probability that coherence time is 1.8 min or longer is 0.8. Using a parabolic approximation for the acoustic wave equation with sound speeds fluctuating from internal waves, a Monte-Carlo model yields coherence time of 1.8 min or more with probability of 0.9. For spatial coherence, two subsections of the array are compared, which are separated by 142 and 370 m in directions perpendicular and parallel to the geodesic, respectively. Measured coherence is 0.54. This is statistically consistent with the modeled 95% confidence interval of [0.52,0.76]. The difference of 370 m parallel to the section causes spatial coherence to degrade deterministically by a larger amount than the effect of internal waves acting on the 142-m separation perpendicular to the section. The models are run without any tuning with data.
Cross-correlation of ship noise for water traffic monitoring.
Authors: Fillinger Laurent , Sutin Alexander , Sedunov Alexander
Published: October 2009

Various aspects of the monitoring of ship traffic using correlation of signals recorded by a pair of hydrophones are considered and demonstrated on real signals recorded in the Hudson River. The underwater acoustic noise generated by ships reaches the various hydrophones with a delay depending on their relative positions. That delay can be extracted by cross-correlation and can serve as a basis for determination of the direction of the ship. This method allowed finding directions for several ships in heavy traffic of Hudson River. The vessel triangulation can be done using information from two or more appropriately located hydrophone pairs. Another application demonstrated is separation of the acoustic signature (noise spectra) from several ships. The last application is the estimation of the ship noise modulation spectrum that is related to propeller and shaft rotation by means of short time cross-correlation. Comparison with the conventional detection of envelope modulation on noise method shows a close match. [This work was partially supported by ONR Project N00014-05-1-0632: Navy Force Protection Technology Assessment Project and by the U.S. Department of Homeland Security under Grant No. 2008-ST-061-ML0002.]
Extraction of acoustic signals using blind source separation method.
Authors: Zhu Na , Wu Sean
Published: October 2009

This paper presents the results of acoustic feature extraction using blind source separation. The objective of this study is to separate individual acoustic signals based on measurements of overall signals without knowing the number of sources, their locations, and how signals are mixed. The only requirements are (1) the acoustic sources are statistically independent, namely, knowledge of one source gives no information on that of the other, (2) signals are non-Gaussian, and (3) the number of sources is no more than that of microphones. Numerical simulations are conducted based on input data collected by four microphones in a free field, and results are obtained using fast independent component analysis (ICA) in time domain. Different types of acoustic sources, including human speech, music, impulsive sounds, machine noise, helicopter sounds, etc., are used. The impacts of microphone spacing and locations, source locations, signal to noise ratio, sampling rate, and various methodologies such as maximization of non-Gaussianity, maximal likelihood estimation, minimization of mutual information, etc., on separations of individual sources are examined. Results show that different approaches lead to different levels of success in source separation. In general, satisfactory results can be obtained when sources are spatially isolated and reverberation effects are negligible.
Fully-coupled fluid-structure interaction simulation of vocal folds.
Authors: Zhang Lucy , Wang Xingshi , Krane Michael
Published: October 2009

In this talk, the human vocal folds are modeled and simulated using a fully-coupled fluid-structure interaction method. This numerical approach is efficient in simulating fluid and deformable structure interactions. The two domains are fully coupled using an interpolation scheme without expensive mesh updating or re-meshing. The method has been validated through rigorous convergence and accuracy tests. The response of the fluid affects the elastic structure deformation and vice versa. The goal of this study is to utilize this numerical tool to examine the entire fluid-structure system and predict the motion and vocal folds by providing constant inlet and outlet pressures. The input parameters and material properties, i.e., elastic and density of the vocal folds used in the model, are physiological. In our numerical results, the glottal jet can be clearly identified; the corresponding pressure field distribution and velocity field are presented.
High-precision frequency analysis of vocal acoustic spectra.
Authors: Matteson Sam , Lu Fang-Ling
Published: October 2009

Earlier work by the authors has demonstrated that the primary overtone series of control subjects is remarkably harmonic; that is, the overtones are very nearly integral ratios of the fundamental. Individuals experiencing dysphonia of various kinds exhibited inharmonicities greater than 10 ¢, however. The current work extends the preliminary investigation and examines the origin of other non-harmonic peaks in high-precision acoustic spectra of both control subjects and those complaining of vocal problems. The authors interpret the non-harmonic peaks in terms of the mechanics of the vocal fold-air stream interaction and comment on the potential of these features for diagnosis of pathology.
Characterization of the airflow through a scaled physical vocal fold model with a unilateral polyp.
Authors: Seawright Angela C. , Erath Byron D. , Plesniak Michael W.
Published: October 2009

The formation of vocal fold polyps, caused by trauma, interferes with normal speech, causing hoarseness or breathiness during phonation. The objective of this study is to investigate the disruption of the glottal flow field due to the presence of a unilateral vocal fold polyp. An ellipsoidal polyp was molded using silicone and incorporated onto the right medial surface of a driven, 7.5 times physiological size vocal fold model. Particle image velocimetry was used to observe the air flow through the vocal folds along a coronal section at discrete phases of the phonatory cycle. Air flow was scaled to match physiological values of Reynolds, Strouhal, and Euler numbers. Data were acquired in planes bisecting the polyp and others offset anterior and posterior to the center of the polyp, in order to ascertain any three-dimensionality of the disrupted flow. The resulting velocity measurements and transglottal pressure drops were compared to previous results from normal vocal fold motion. Differences in flow characteristics indicating a change in the phonatory capacity of patients with polyps are reported. [Work funded by NSF Grant No. CBET-0828903.]
Applying Lindsay’s acoustical wheel to architectural acoustics.
Authors: Talaske Richard
Published: October 2009

The acoustic design of performance spaces has advanced over the decades due to the influence of many acoustics disciplines. Psychological acoustics research has helped establish criteria, allowing acousticians to fashion designs which satisfy listeners. Speech perception has advanced within drama spaces, thereby offering more artistic freedom. Structural acoustics and vibration methods have helped facilitate on-stage communication via tactile vibration. The effects of noise on the live event have become better understood, leading to a more satisfying performance experience. And audio systems have been developed, both indoors and outdoors, to embellish architecturally created sound environments. This discussion on architectural acoustics recognizes this confluence of diverse perspectives on acoustics and describes how a broad knowledge base has been channeled into the design of performance facilities for the benefit of patrons and performers alike. The evolution of the design of performance and assembly spaces will be discussed from the perspectives of acoustics, function, and aesthetics. The historical influences of society and technology will be presented as the basis to suggest a glimpse of what performance spaces might be like in the future.
The impact of structural design decisions on building acoustics.
Authors: Campbell Scott D.
Published: October 2009

Choices made by the architect and structural engineer at all phases of the design process affect the acoustic and vibration characteristics of a building. The basic structural system locks into place acoustic and vibration properties that are very difficult to change after the fact. Even when a favorable structural system is selected, details such as floor slab design and connection type can adversely affect the acoustic and vibration performance. Current trends toward less expensive structural systems, and hence lighter and more flexible systems, reduce the ability of a building to resist transmission of sound and vibration. In addition, failure to involve an acoustic or vibration consultant early in the process makes it much harder to correct these problems. All of these issues are compounded when the building is located in a high seismic or wind area. The special design requirements are often at odds with proper acoustic and vibration design. This paper will explore the impact of typical structural design options on the acoustic and vibration properties of buildings, and discuss some of the remedies available for mitigating the impact.
Best practice for applying seismic restraint to vibration isolated equipment.
Authors: Pooler James N.
Published: October 2009

In many areas of the county and throughout the world, seismic restraint is required for mechanical equipment per local building codes and The International Building Code. If seismic restraint is not properly designed or properly installed, vibration isolation efficiency could be affected. Properly designed seismic restraint systems allow for vibration isolation while effectively transmitting the seismic loads into the building structure. This presentation will also use case studies to review the issues and solutions for applying seismic restraint to vibration isolated mechanical equipment.
Bird hearing and communication in natural environments.
Authors: Dooling Robert J.
Published: October 2009

A soundscape, taken from human work, generally refers to the complex of sounds that are integral to and formed by a particular natural environment. Some of this sound is from abiotic sources (e.g., wind, streams, various anthropogenic sources, etc.) while some of this sound may come from conspecifics or other animals. In nature, all sound reaching an animal’s ears, whether from biotic or abiotic sources, is shaped by this natural environment. Noise, sound distortion, and frequency-dependent attenuation can increase detection thresholds and interfere with discrimination, recognition, and localization of sound sources. Signals degraded by travel through the environment and/or affected by masking can in turn adversely affect critical behaviors such as mate attraction, territorial defense, parent-offspring communication, predator avoidance, and prey detection. Using laboratory psychophysical data from several species of birds, some interactions among these factors and the implications for communication in a noisy environment are described. Species differences in auditory sensitivity and the characteristics of the environment are major factors in predicting whether a given soundscape limits communication between birds or interferes with detection of other biologically important sounds. [Work supported by NIH grant to R.J.D.]
The effect of different schedules of reinforcement on the structure of the black-capped chickadees’ chick-a-dee call.
Authors: Proppe Darren S. , Sturdy Christopher B.
Published: October 2009

It is known that adult songbirds can modify the output and structure of their vocalizations in different behavioral contexts. However, whether changes in the abiotic environment (i.e., food availability) also affect vocal structure is less understood. Here we test whether the chick-a-dee calls of the black-capped chickadee differ between birds on two different schedules of reinforcement (continuous and partial) and in two different behavioral contexts (singing alone and mildly alarmed by human intrusion). Our results reveal differences in the composition and pitch of chick-a-dee calls from birds in different behavioral contexts and on different schedules of reinforcement. However, calls from birds on the different schedules of reinforcement become more similar when evoked by human intrusion. We suggest that these results may represent differences in the energy dedicated to call production. If vocal structure varies consistently with changes to the abiotic environment, we may be able to detect environmental changes (i.e., warming and reduction in available forage) through analysis of vocal traits. While we demonstrate differences in call structure based on schedules of reinforcement, results from field studies in multiple regions will divulge whether these vocal changes are consistent and useful for analysis of abiotic conditions.
Killer whale discrete pulsed call variation.
Authors: Grebner Dawn M. , Bradley David L. , Capone Dean E. , Parks Susan E. , Miksis-Olds Jennifer L. , Ford John K. B.
Published: October 2009

Animals can increase and diversify vocal complexity and call content by altering internal features within a call. The Northern Resident orca pods, residing off British Columbia, each have their own dialect of structurally discrete and highly stable pulsed calls. The objective of this study is to determine if there are distinctive internal acoustic features within the defined envelope of a single discrete pulsed call (N04) which could potentially relay the signaler’s behavioral circumstance. Orca discrete pulsed calls are highly complex with varying time-frequency slopes and multiple sidebands. This analysis began with the parsing of the N04 call into different subtypes based on distinctive changes in time-frequency slopes found in the call spectrograms. Call subtypes were verified using discriminant analysis, and changes in slope trends (ascending, descending, or constant frequency) at designated locations along the calls were compared. Variations in slopes were found between subtypes predominantly in the calls’ front and terminal regions. Clear and reliable acoustic cues within a discrete pulsed call could not only provide receivers with the physical location and group affiliation of the signaler but also would alert receivers to the signaler’s behavioral state or prey catch which would be vital information for a prey-sharing species.
Environmental assessment of offshore wind power generation near Rhode Island: Acoustic and electromagnetic effects on marine animals.
Authors: Miller James H. , Potty Gopu R. , Vigness Raposa Kathleen , Casagrande David , Miller Lisa , Crocker Steven E. , Tyce Robert , Preston Jonathan , Roderick Brian , Nystuen Jeffrey A. , Scheifele Peter M.
Published: October 2009

An offshore wind farm is planned for Rhode Island coastal waters. The developer has proposed to deploy wind turbines in two stages: 5 turbines in shallow waters 5 km south of Block Island and 100 turbines in deeper waters 30 km to the east. As part of the planning of the proposed offshore wind power generation project under the Rhode Island Special Area Management Plan, ambient acoustic and electromagnetic measurements were made in the area. Two passive acoustic listener (PAL) systems were deployed within 4 km of Block Island from October 6 to November 11, 2008. Data from the PALs were used to compute the ocean acoustic noise budget and other statistics by source. Transmission loss measurements were also made to support the noise budget calculation. Measurements of airborne noise from a 1.5-MW land-based wind turbine already in operation in Rhode Island were made. To support the electromagnetic effect study, an underwater magnetometer was towed at the two proposed sites and over an operational underwater 23-kV power cable. A preliminary assessment of the effects of the offshore wind farm on marine animals at these sites will be presented. [Funding provided by the RI Office of Energy Resources.]
Galfenol technology, state-of-the-art.
Authors: Summers Eric , Slaughter Julie
Published: October 2009

Galfenol is a recently discovered magnetostrictive material containing iron (Fe) and gallium (Ga) in various ratios based on desired properties. This alloy system exhibits several unique advantages over legacy smart materials such as Terfenol-D and PZT. Galfenol can be readily machined using conventional machining techniques, it can be formed into various geometries using standard metal working practices such as forging and rolling, alloys can be produced with large internal pre-stresses negating the necessary presence of external pre-load mechanisms, and Galfenol can be welded to other ferrous materials without issue. All of these attributes make Galfenol an attractive new material for the applications engineer. In this presentation, the current state-of-the-art of Galfenol technology will be discussed along with future technology development. Static and dynamic magnetic properties will be presented for various Galfenol alloys; in addition, mechanical properties and available processing routes will be discussed. The work presented includes progress in transitioning this technology from university and laboratory-scale to small-scale production and the impact of material processing and availability on transducer applications.