bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrational characteristics of Balinese gamelan metallophones.
Authors: Jones Molly E. , Gee Kent L. , Grimshaw Jeremy
Published: March 2010

A study of the 16 metallophones from a Balinese gamelan has been conducted. Acoustical recordings of metallophone bars being struck were used to examine ratios of overtone frequencies to the fundamental. Results showed large variability in the number and ratios of overtones present. Scanning laser Doppler vibrometry measurements made on several bars also revealed great variability in mode shapes present. The distribution of prominent overtones and their modal shapes do not appear to match those of Western metallophones. Notably, the overall gamelan metallophone characteristics are quite dissimilar to the glockenspiel, which disagrees with previous studies. [This study was supported by the National Science Foundation through its Research Experiences for Undergraduates program.]
An introduction to the acoustics of playing the horn.
Authors: Zartman David J
Published: March 2010

In the art of music, a good performer can make a low-quality instrument sound passable, while a bad performer will not play well even on the best instrument in existence. Rather than merely focusing on the properties of the instrument, it is useful to provide the musician with some of the acoustical principles involved with playing the horn well. At the same time, this provides a medium to enable the acoustician to understand some of the intricacies a musician must balance well to create a pleasing sound.
Acoustical studies on conch shells.
Authors: Prasad M.G. , Rajavel B.
Published: March 2010

Sound from blowing a conch shell is known for its tonal quality. Its use in many cultures is known. In Hindu culture, conch shell is blown on several auspicious occasions such as festivals, worship, and rituals. A conch shell can be modeled as a horn in its acoustical behavior. This work presents an acoustical study in terms of the spectral characteristics of the shell. The study also presents the influence of parameters such as placing hand in the mouth of the conch shell and the size of conch shell on the spectral characteristics.
The shape of musical sound: Real-time visualizations of expressiveness in music performance.
Authors: Ren Gang , Lundberg Justin , Bocko Mark F. , Headlam Dave
Published: March 2010

Despite the complex multi-dimensional nature of musical expression in the final analysis, musical expression is conveyed by sound. Therefore the expressiveness of music must be present in the sound and therefore should be observable as fundamental and emergent features of the sonic signal. To gain insight into this feature space, a real-time visualization tool has been developed. The fundamental physical features—pitch, dynamic level, and timbre (as represented by spectral energy distribution)—are extracted from the audio signal and displayed versus time in a real-time animation. Emergent properties of the sound, such as musical attacks and releases, the dynamic shaping of musical lines, timing of note placements, and the subtle modulation of the tone, loudness, and timbre can be inferred from the fundamental feature set and presented to the user visually. This visualization tool provides a stimulating music performance-learning environment to help musicians achieve their artistic goals more effectively. Such visualizations and interactions with musical sound also will promote the semantic understanding of an expressive musical language.
Robust audio watermarking scheme based on spectral modeling synthesis.
Authors: Dhar Pranab , Kim Cheol Hong , Kim Jongmyon
Published: March 2010

This paper proposes a new watermarking scheme based on spectral modeling synthesis for copyright protection of digital contents. In our proposed scheme, a short time Fourier transform (STFT) is applied to the original signal. Prominent spectral peaks of each frame are then detected and represented by sinusoidal parameters. The residual component is computed by removing all the prominent peaks from the spectrum, transforming the spectrum back to the time domain using inverse fast Fourier transform, and overlap-adding the frames in time. In addition, a peak tracking unit keeps the sinusoidal parameters and forms peak trajectories. Watermarks are then embedded into the most prominent peak of each frame in the peak trajectories. Watermarked signal is computed by the sinusoidal synthesis process and then adding the sinusoids with the residual signal. Watermarks are detected by using the inverse operation of watermark embedding process. Simulation results indicate that the imperceptible watermarks embedded into four different kinds of music sounds using the proposed scheme are robust against several attacks such as noise addition, cropping, re-sampling, re-quantization, and MP3 compression, showing similarity values ranging from 0.8 to 0.9. [Work supported by KOSEF, R01-2008-000-20493-0.]
Miniature thermoacoustic engine: Experiments and modeling.
Authors: Matveev Konstantin I. , Jung Sungmin
Published: March 2010

A miniature standing-wave thermoacoustic engine was constructed and tested with four quarter-wavelength resonators having lengths in the range of 57–124 mm. 80-ppi reticulated vitreous carbon (RVC) foam was applied as a stack, and an atmospheric air served as a working fluid. The critical temperature difference between the stack ends, corresponding to the sound onset, was recorded in the range of 200–300 °C. A thermoacoustic model was developed to predict the critical temperature difference across the stack. The model allows for user-defined thermoacoustic functions for the stack. Results obtained with the capillary-based theory for tortuous media and thermoacoustic functions previously measured for RVC demonstrate a trend qualitatively consistent with our data, while the quantitative agreement is lacking. Modeling results obtained with thermoacoustic functions for a parallel-plate stack can approximate experimental data, if the appropriate plate spacing is selected. [Work supported by the NSF Grant No. 0853171.]
Pressure, temperature, and dissolved gas dependence of dielectric breakdown in water.
Authors: Sukovich Jonathan , Holt R. Glynn
Published: March 2010

It has been shown experimentally that the optical breakdown strength of water is a pressure dependent quantity, growing with increasing pressure. The dependence of the breakdown strength on temperature and dissolved gas concentration over a larger range of pressures will be observed. Using a custom fabricated pressure vessel and high-power Nd:YAG laser, breakdown events will be generated and observed over a range of pressures from 0 to 25 kpsi. Observations of breakdown events will be made using a high-speed photodetector located behind the pressure vessel’s optical windows. Dissolved gas concentration will be controlled and varied using a custom water preparation system over a range from water’s vapor pressure (∼20 torr) to atmospheric pressure. Temperature will be monitored using a thermocouple attached to the pressure vessel and the temperature dependence will be measured over a range from 20 to 35 °C. A comparison between current single detector methods and previous imaging methods of using breakdown to determine absolute pressure will then be made. [Work supported by Impulse Devices, Inc.]
Temporal evolution of laser-nucleated bubble clouds in an acoustic resonator.
Authors: Anderson Phillip A. , Holt R. Glynn
Published: March 2010

Using high-speed digital imaging, the evolution of laser-nucleated bubble clouds over multiple acoustic cycles is observed. Five 7×7 custom phase gratings are employed to produce 245 beams, which are then focused into the center of a spherical resonator capable of high static and acoustic pressure. The dependence of the evolution of the bubble cloud on several system parameters is measured. Notably the resulting cloud(s) depend strongly on the phase of the laser firing, the laser energy per pulse, and the acoustic pressure. Number of bubbles, radius of individual bubbles, and effective radius of clouds will be reported as functions of time. The interplay between cloud dynamics and shock waves will also be discussed. [Work supported by Impulse Devices, Inc.]
Theoretical analyis of Schwinger's conjecture on sonoluminescence in relation to the boosting of sonluminescent transduction efficiency.
Authors: Woodsum Harvey C.
Published: March 2010

In a previous paper [Spring ASA, Salt Lake (2007)], we have considered the potential viability of Schwinger’s conjecture that sonoluminescent light radiation, which results from acoustically developed cavitation, derives from zero-point energy of the vacuum. In our prior paper, we considered the nonlinear interaction of zero-point electromagnetic modes in a cavitating bubble, through the Euler–Heisenberg theory for the scattering of light by light. Good agreement was found between theory and experiment with regard to both the efficiency and spectrum of the sonoluminescent radiation generated using a single acoustic frequency. We now consider a comparison of this theory with other experiments [Phys. Rev. Lett. 81, 1961–1964 (1998)] which have demonstrated that cavitation bubbles created with acoustic waves having both first and second harmonics present, and having particular amplitude and phase arrangements, can result in sonoluminescent transduction efficiency increases of up to 300%. At this point in time, the predictive power of the current theory appears promising.
Nonlinear poroacoustic flow in rigid porous media.
Authors: Jordan Pedro , Fulford Jim
Published: March 2010

An acoustic acceleration wave is defined as a propagating singular surface (i.e., wavefront) across which the first derivatives of the velocity, pressure, or density exhibit jumps. In this talk, the temporal evolution of the amplitude and the propagation speed of such waves are investigated in the context of nonlinear acoustic propagation in rigid porous media. By considering the exact conservation/balance equations, it is shown that there exists a critical value, the constant α*(>0), of the initial jump amplitude such that the acceleration wave magnitude either goes to zero, as t→∞, or blows up, in finite time, depending on whether the initial jump amplitude is less than or greater than α*. In addition, stability is addressed; a connection to traveling wave phenomena is noted, for which an exact traveling wave solution is obtained; and a comparison with the linearized case, i.e., the well-known damped wave equation, is also presented. Finally, the numerical solution of an idealized, nonlinear initial-boundary value problem involving sinusoidal signaling in a fluid-saturated porous slab is used to illustrate the finite-time transition from acceleration to shock wave, which occurs when the initial jump amplitude exceeds α*. [Work supported by ONR/NRL funding.]
Acoustic performance predictions via a general theory for the scattering of sound by sound with experimental data from an operational parametric sonar system.
Authors: Woodsum Harvey C.
Published: March 2010

In results previously described [J. Acoust. Soc. Am. 95, 2PA14 (1994)], a general theory for the scattering of sound by sound has been developed as an exact solution to the Lighthill–Westervelt equation of nonlinear acoustics. Most recently, a computer model based on this theory has been developed in order to support design analysis and performance prediction for parametric array echo-ranging systems and has been applied to a currently deployed operational parametric sonar. The present theory and model have the potential to support a wide range of analyses, including development of beam patterns, source levels, transient waveform effects, as well as the analysis of scattering of sound by sound from intersecting beams as well as the prediction of performance of parametric sources having multiple simultaneous transmit beams. Both the theoretical basis for the model and agreement with experimental data are presented.
Imaging multiple masked nonlinear scatterers applying a combination of time reversal principles and the selective source reduction method.
Authors: Vanaverbeke Siegfried , Van Den Abeele Koen , Anderson Brian E. , Scalerandi Marco
Published: March 2010

Inherent limitations of the traditional time reversal process in the case of multiple sources or scatterers make it impossible to distinguish them individually. The selective source reduction (SSR) method employs a subtraction technique to selectively suppress in amplitude (and ideally eliminate) a time reversed focal signal that is masking another focus. In previous work, Scalerandi et al. and Anderson et al. successfully applied the SSR method to identify masked primary sources in a fully linear medium. Here, we extend the capabilities of the SSR method to deal with (i) secondary sources (for example, scattering caused by embedded defects) and (ii) nonlinear scattering generated during the ultrasonic wave propagation as well. We call this new method selective source reduction based on nonlinear time reversed acoustics (SSR-NLTRA). In the extended approach, the contribution of all primary sources is first eliminated by means of the scaling subtraction method. Subsequently, the SSR-TRA method is applied to the remaining nonlinear content of the signals. We show by means of two dimensional wave propagation simulations that the new method can be applied iteratively to successfully image multiple masked nonlinear defects.
Vacuum ear plug.
Authors: Lenhardt Martin L.
Published: March 2010

A passive inexpensive hearing protection device (HPD) will be described that provides hearing protection, which is simple to use and comfortable over hours of use. Protection from impact sounds will be provided by creating a negative pressure between the plug tip and the eardrum (−100-mm H2O or −1 kPa). The negative pressure will be created by squeezing the peripheral plug end, evacuating a fixed amount of air from the canal. The aperture diameter is 0.010 in. In effect the pump plug will have a similar acoustical action on the eardrum as a normal stapedius muscle contraction, but without its limitations (too slow and fatigue). An external flexible bladder forms the end which is held in the fingers to be inserted into the ear canal. The vacuum mechanism consists of bulb on a polypropylene frame embedded in a closed cell urethane flanged housing. With a negative pressure of −2 kPa the transmission loss is 20–25 dB. It is estimated that a negative pressure of −1 kPa would result in a transmission loss of about 15 dB. The vacuum effect is maximal in the low frequencies which will also attenuate body conducted sounds by reducing ossicular inertial.
Growth of otoacoustic emission suppression as a function of frequency and level in humans.
Authors: Gorga Michael P. , Neely Stephen T. , Kopun Judy, G. , Tan Hongyang
Published: March 2010

DPOAE suppression was measured for 11 suppressor frequencies (f3) surrounding each of eight f2 frequencies (0.5–8 kHz) and six L2 levels (10–60 dB SL). A total of 63 normal-hearing subjects participated, with data from 20 subjects at each f2, L2 combination. Measurement-based stopping rules were used, such that averaging continued until the noise −25 dB SPL, the SNR 25 dB, or 210 s of artifact-free averaging had been completed. These stopping rules resulted in reliable measurements, even for conditions in which the SNR typically is poor (low f2 frequencies and low L2 levels). Suppression growth as a function of f3 was similar across f2 frequencies and L2 levels. Specifically, low-frequency suppressors relative to f2 had higher suppression thresholds but more rapid growth of suppression, compared to suppressor frequencies close to f2. Suppression growth for f3 frequencies above f2 was slow, even in comparison to suppression growth when f3 ¡Ö f2. This overall pattern was evident for all f2 frequencies and for a wide range of L2 levels. These findings suggest that suppression growth is similar across a wide frequency range in humans. [Work supported by the NIDCD R01 2251 and P30 4662].
Perception and discrimination of synchronous and asynchronous tones.
Authors: Wojtczak Magdalena , Oxenham Andrew J. , Baird Anna C.
Published: March 2010

Studies of auditory-brainstem responses show that the response to a click is less synchronized than the response to an upward-chirp designed to compensate for the dispersion of basilar-membrane traveling-wave [Dau et al., J. Acoust. Soc. Am. 107, 1530–1540 (2000)]. However, upward-chirps are perceived as less compact than the clicks despite producing a more synchronized response along the basilar-membrane, suggesting the existence of a mechanism compensating for different traveling-wave delays [Uppenkamp et al., Hear. Res. 158, 71–83 (2001)]. This study evaluated synchrony and asynchrony perception and discrimination using tonal stimuli that excited remote places along the basilar membrane. Potential within-channel cues were masked using noise bands that were geometrically centered between the test tones. Level effects were investigated using two levels of the test tones, 20-dB SL and 85-dB sound pressure level (SPL). In addition, perception and discrimination of synchrony and asynchrony were measured for tones presented in noise bands at signal-to-masker ratio of 20 dB. The pattern of results for masked 85-dB SPL tones resembled that for unmasked 20-dB SL tones. The role of auditory-filter bandwidths and the existence of a compensating mechanism in the perception of across-channel synchrony and asynchrony will be discussed. [Work supported by NIH Grants R01DC03909 and R01DC010374].
Limiting factors in auditory discrimination of frequency ratios.
Authors: Stoelinga Christophe N. J. , Lutfi Robert A.
Published: March 2010

Frequency ratios convey meaningful information for speech and many natural sounds. However, little is known regarding our ability to discriminate frequency ratios [see Fantini and Viemeister (1987). Auditory Processing of Complex Sounds (Lawrence, Hillsdale, NJ)]. The present study measured the relative contribution of two factors expected to limit discrimination: decision criterion and internal noise. In an adaptive, two-interval, forced-choice procedure with frequency rove, 11 highly trained listeners discriminated a change in the frequency ratio between two equal-intensity tones. The separate influence of decision criterion and internal noise was determined from scatter plots giving listeners’ trial-by-trial responses as a function of the frequencies of the two tones. The plots reveal listeners to initially base their judgments on one tone alone (almost always the higher of the two) but after training to place greater reliance on both tones. Some listeners were able to achieve the optimal decision criterion of weighting both tones equally, so that the deviation from perfect performance was due only to internal noise. With continued practice over the course of many trials (at least ten 1000-trial sessions), listeners improved their performance by either improving their decision criterion or reducing internal noise. [Research supported by NIDCD grant 5R01DC006875-05.]
Transient sex differences during development on two auditory tasks attributable to earlier maturation in males.
Authors: Huyck Julia Jones , Wright Beverly A.
Published: March 2010

Recent evidence suggests that the development of naïve performance on some auditory perceptual tasks can continue well into adolescence. Of interest here was whether there are sex differences in the maturation rate on three such tasks, temporal-interval discrimination, tone detection in forward masking, and tone detection in backward masking. To investigate this issue, performance was compared between males and females in multiple age groups on these three tasks (n per sex in each age group=9–20). There were no sex differences for backward masking. However, males reached adult-like performance earlier than females on the other two tasks: forward masking (males at ∼12 years, females at ∼15 years) and temporal-interval discrimination (males at 14 years, females at >14 years, on each of three separate conditions). Surprisingly, the male advantage occurred only during adolescence. Thus, on two of the three late-developing auditory abilities examined, males matured more quickly than females, but did not differ from females either early in development or once mature performance had been reached. These results demonstrate that there can be transient sex differences during development owing to differences in maturational rate. [Work supported by NIH/NIDCD.]
Spectral weight analysis of commodulation masking release.
Authors: Tabuchi Hisaaki , Berg Bruce G.
Published: March 2010

Spectral weight estimates are obtained in a commodulation masking release (CMR) experiment in which masking and flanking bands each consist of five equal-intensity tones spanning 20 Hz. The masking and flanking bands are centered at 1000 and 900 Hz, respectively, and the signal is an increment in the intensity of the 1000 Hz component. The phases for the five components of the masking band are randomly sampled on each trial and are identically assigned to the components of the flanking band, yielding commodulated bands. A small, random intensity perturbation is added to each component of the stimulus, and an analysis of trial-by-trial responses provides spectral weight estimates. Spectral weights are also obtained from simulations of two multiple channel models [Hall et al., J. Acoust. Soc. Am. 76, 50–56 (1984); S. Buus, J. Acoust. Soc. Am. 78, 1958–1965 (1985)] and one single-channel model [B. G. Berg, J. Acoust. Soc. Am. 100, 1013–1023 (1996)]. Data for most subjects show strong support for Hall’s multiple-channel model. [Work supported by NSF BCS-07464003.]
Musical context affects detection of pitch differences in tones with different spectra.
Authors: Borchert Elizabeth M. O. , Oxenham Andrew J.
Published: March 2010

Pitch plays an important role in complex auditory tasks such as listening to music and understanding speech, yet pitch comparisons are more difficult when tones have different spectra. Since tones are rarely heard in isolation, the surrounding context may help or hinder pitch comparisons. The first study presented listeners with tone pairs in isolation or immediately following a tonal context, which consisted of a portion of a descending major scale with the target as the tonic. Listeners’ performance improved in the presence of the tonal context, but only when the tones within a pair differed in spectral content. In the second experiment, a variety of contexts were used, with the goal of discriminating between effects of tonal hierarchy and effects of predictability. Even with maximal predictability, presenting tone pairs after an “atonal” context consisting of notes from an octatonic scale yielded poorer performance than tone pairs in isolation. The results suggest that any advantage listeners derived from the tonal context in our first experiment was related more to placing the tone into an over-learned tonal hierarchy than to the likelihood of the target pitch within a predictable context. [Work supported by NIH Grant R01 DC 05216.]
Tonotopic gradients in neural interaural time difference processing: A modeling study of the medial superior olive.
Authors: Chung Yoojin , Colburn H. Steven
Published: March 2010

The interaural time difference (ITD) is the primary cue for sound localization; yet many basic questions about the biophysical mechanisms remain. In the mammalian auditory system, neurons in the medial superior olive (MSO) are tuned to ITD as well as frequency. In this study, the effects of key parameters in MSO models, such as the membrane time constants and the number and strength of synaptic inputs on ITD sensitivity to pure tones, were explored with particular attention to the best-frequency dependence of these parameters. Results show that ITD tuning is dependent on neuron membrane characteristics (i.e., the shape and time constant of the membrane response), on the strength of individual synaptic inputs, and on stimulus properties such as frequency and intensity. Models with slow response times and weak synaptic inputs show good ITD sensitivity for low-frequency tones, whereas models with fast response times and strong synaptic inputs exhibit good ITD tuning for high-frequency tones. This dependence of ITD sensitivity on membrane properties in the model suggests that parameters important for ITD tuning depend on the best frequency of the neurons, in contrast to the view that the binaural mechanism is homogeneous along the tonotopic axis.
Perception of temporally interrupted speech: Effects of two concurrent gating rates on intelligibility.
Authors: Shafiro Valeriy , Sheft Stanley , Risley Robert
Published: March 2010

Perception of temporally interrupted speech was investigated with either one or two concurrent square-wave gating functions. Sentences were interrupted at a single rate of 1, 2, 4, 8, 16, 24, or 32 Hz with a 50% duty cycle. For each rate between 1 to 8 Hz, stimuli were additionally gated at a secondary rate ranging from twice the primary rate up to 32 Hz. The secondary gating rate thus interrupted only the segments of speech which were left intact after application of the primary gating function to reduce by half the remaining speech content independent of secondary rate. With a single gating function, intelligibility scores increased with rate, reaching perfect accuracy at 8 Hz. Application of the second gating function led to a decrease in intelligibility which was greatest when the secondary rate was twice the primary rate, a condition equivalent to a 25% duty cycle of the primary rate. Further increase in the secondary rate generally led to an improvement in intelligibility, although never to the level achieved with the primary rate alone. The incomplete recovery of intelligibility scores at fast secondary gating rates suggest disruption of separate perceptual processes by each of the two concurrent interruption rates.
Novel lightweight vibration absorbers for marine structures.
Authors: Harne Ryan L. , Fuller Chris R.
Published: March 2010

When combined with attached motors and rotating machinery, the lightly damped, thick plating required in maritime applications becomes a broadband noise and vibration control problem. A typical solution is to adhere heavy and dense damping materials for dissipation of the plate vibrational energy. In order to attenuate low frequencies, significant mass must be added to the structure. This paper will review the development of two, new passive treatments intended to resolve this issue. HG blankets are constructed using small masses embedded into poroelastic material. Together with the inherent stiffness of the poroelastic material, the masses become embedded mass-spring dampers and their presence is found to notably increase the low-frequency transmission loss of the host material. DVAs are compact vibration absorbers that distribute continuous mass and spring elements over the surface while generating ample reactive damping at low frequencies. This paper will overview the concepts and development of adapting DVAs and HG blankets for use on heavy plate structures, their testing for broadband control performance, as well as their versatility for thinner panels. A comparison with a conventional, marine noise control treatment will be considered. [This work was supported by Northrop Grumman Shipbuilding-Newport News.]
Speech analysis in accident investigation.
Authors: Brenner Malcolm
Published: March 2010

The NTSB investigates major transportation accidents in the United States to make recommendations to prevent their recurrence. The Safety Board also examines new technologies that might assist investigations. In conducting its work, the NTSB has found speech analysis a useful new technology for providing secondary evidence on operator state for issues such as psychological stress, alcohol impairment, physical straining, and hypoxia. This talk provides examples from two investigations: the grounding/oil spill of the Exxon Valdez tanker and the crash of a Boeing 737 airliner at Pittsburgh.
Automatic methods to monitor the speech of Parkinson’s patients with deep brain stimulators.
Authors: van Horne Craig , Chenausky Karen , MacAuslan Joel , Massari Carla , McCormick Marianna
Published: March 2010

Parkinson’s disease (PD) is a neurodegenerative disease causing hypokinetic dysarthria, associated with “blurred” or underarticulated speech, imprecise consonants, and, sometimes, irregular syllable trains. Within the past decade, deep brain stimulation (DBS) of the subthalamic nucleus (STN) has provided substantial benefit to PD patients. DBS treatment has largely been directed toward the motoric features of PD: bradykinesia, rigidity, and tremor, but its effects on speech vary. The speech of PD patients receiving DBS treatment, with or without accompanying medical therapy, was analyzed for rate (syllables per second), regularity (relative deviation of syllable length), stop consonant spirantization (a measure of stop consonant precision), vowel ratio (length of vowel to length of syllable), and other features using automatic routines written specifically for the purpose. Patients’ speech is more variable on DBS stimulation than on medication or no treatment. It is possible to find a combination of DBS settings for each patient that relieves their motor symptoms and returns their speech to normal. These findings suggest that it is possible to improve speech along with the general motor symptoms of PD. Furthermore, automatic analyses show promise as sources of feedback for neurologists to use in optimizing DBS settings for speech.
Impact of cognitive load and frustration on drivers’ speech.
Authors: Bořil Hynek , Kleinschmidt Tristan , Boyraz Pinar , Hansen John H. L.
Published: March 2010

Secondary tasks such as cell phone calls or interaction with automated speech dialog systems (SDSs) increase the driver’s cognitive load as well as the probability of driving errors. This study analyzes speech production variations due to cognitive load and emotional state of drivers in real driving conditions. Speech samples were acquired from 24 female and 17 male subjects (approximately 8.5 h of data) while talking to a co-driver and communicating with two automated call centers, with emotional states (neutral, negative) and the number of necessary SDS query repetitions also labeled. A consistent shift in a number of speech production parameters (pitch, first format center frequency, spectral center of gravity, spectral energy spread, and duration of voiced segments) was observed when comparing SDS interaction against co-driver interaction; further increases were observed when considering negative emotion segments and the number of requested SDS query repetitions. A mel frequency cepstral coefficient based Gaussian mixture classifier trained on 10 male and 10 female sessions provided 91% accuracy in the open test set task of distinguishing co-driver interactions from SDS interactions, suggesting—together with the acoustic analysis—that it is possible to monitor the level of driver distraction directly from their speech.
Measuring speech and language characteristics of effects of medications on cognition.
Authors: Pakhomov Serguei , Marino Susan , Birnbaum Angela , Hawkins-Taylor Chamika , Leppik Ilo
Published: March 2010

Many of the drugs prescribed for various diseases and syndromes, including chronic pain and epilepsy, significantly impair cognitive functioning with large individual variation. Language is a highly individualized and directly observable product of human cognition that is central to our everyday functioning. A system for automated language and speech analysis (SALSA) was developed that relies on using an automatic speech recognition engine (HTK 3.4) [Young et al. (2008)] to perform forced-alignment between the audio of spontaneous speech samples and their transcripts to measure a number of speech and language characteristics including fluency, speaking rate, change in fundametal frequency, and information content of spontaneous narratives. The system was piloted on a population of 14 healthy volunteers who participated in a randomized, placebo-controlled study of cognitive effects of an anti-epileptic medication (topiramate). Our preliminary results suggest that SALSA captures a number of fluency and lexical characteristics sensitive to the effects of topiramate, thus providing an objective mechanism to quantify the degree of cognitive impairment in individulas affected by medications. Our current results are consistent with prior work investigating speech and language correlates of mild cognitive impairment [Roark et al. (2007)] and fronto-temporal dementia [Pakhomov et al. (2009)]. [Work supported by a grant from the Univ. of Minnesota Academic Health Crt.]
Nested sampling for room-acoustics energy decay analysis.
Authors: Xiang Ning , Jasa Tomislav , Braasch Jonas
Published: March 2010

Room-acoustic energy decays often exhibit single-rate or multiple-rate behavior in a wide variety of enclosures. There has been an ever increasing need to investigate where and under what conditions the single-rate and or multiple-rate energy decays occur and to quantify/characterize the energy decay process by estimating a set of decay parameters. In this architectural acoustics application, both energy decay model selection and decay parameter estimation are of practical significance. This paper discusses a model-based sound energy decay analysis within a Bayesian framework and applies the most recent Bayesian sampling method (nested sampling) to sound energy decay analysis. The nested sampling reverses the historical Bayesian computation approaches, yielding the Bayesian evidence as the prime target with representative posterior samples available as optional by-products. Bayesian evidence is crucial for model selection, while the representative posterior samples are of central importance for parameter estimation. Taking the energy decay analysis in architectural acoustics as an example, this paper demonstrates that two different levels of inference, decay model-selection and decay parameter estimation, can be cohesively accomplished by nested sampling.
Comparison of fading statistics for shallow and deep acoustic sources in a continental shelf environment.
Authors: Sell Alexander W. , Culver R. Lee , Jemmott Colin W. , Bissinger Brett E.
Published: March 2010

Previous work has shown a noticeable difference in the effects of the ocean environment on signals from shallow and deep moving sources. These effects are seen in received amplitude statistics, and such statistics can be used in passive acoustic depth classification. This talk presents a statistical analysis of signals from a September 2007 shallow water acoustic transmission test performed along the continental shelf off the coast of southeast Florida. The data used include low frequency (between 25 and 450 Hz), continuous-wave signals from a towed source at 100 m depth, as well as tones from surface ships in the area. Using statistical class models in a Minimum Hellinger Distance Classifier, the usefulness of received signal amplitude statistics for passive acoustic source-depth classification is discussed. [Work supported by ONR Undersea Signal Processing.]
Depth discrimination in shallow water by matched-field tracking.
Authors: DelBalzo Donald R. , Leclere James H.
Published: March 2010

Passive acoustic sonars have difficulty in detecting quiet sources in noisy shallow-water environments. The standard approach to improving detection performance is to use a large aperture linear array of horizontally distributed hydrophones and azimuthal processing to increase the signal-to-noise ratio (SNR) through beamforming. A newer approach is to apply matched-field correlation techniques and estimate source locations in depth and range using signals received on a linear vertical array. These localization techniques are not designed for detection of quiet targets and some potential applications preclude the use of vertical arrays for practical reasons, like damage caused by fish trawling. In this work, we examine the utility of matched-field processing on linear and planar horizontal arrays on the ocean bottom in shallow water. We employ a track-before-detect strategy to convert matched-field localizations into submerged source detections in various physical and acoustic environments. We show the advantages of planar compared to linear arrays to discriminate submerged from surface sources as a function of SNR.
A feasibility study on the low probability of intercept sonar.
Authors: Park J. Daniel , Miller David J. , Doherty John F. , Thompson Stephen C.
Published: March 2010

The feasibility of low probability of intercept for sonar is explored. Using a noise-like active sonar signal, the transmitter (platform) employs a matched filter for echo detection while the target is assumed to use an energy detector. Decision statistic distributions are developed and detection performances are compared with a previous work (Gaussian distribution assumed). We then explore the detection advantage the platform can achieve by evasive on-off keying and by optimization of transmitted power. A favorable operating region of the platform in the (low power, small range) region of the (range, power) plane is identified. This suggests that the platform should start detection using a low-power probing signal, increasing power until a reliable detection rate is first achieved while ensuring that the detection rate at the target does not exceed a specified level. Second part of the feasibility study is about covert range estimation. Two matched-filter based algorithms were developed for the platform to obtain credible range estimations while ensuring the target fails to detect the platform. A platform-target encounter scenario was designed for detailed waveform-based Monte Carlo simulation. Characterization of variables in the model was performed to show the feasible conditions of covert range estimation. [Work sponsored by ONR, ULI.]
An experimental scaled-model for coupled volumes with an automated high-spatial-resolution scanning system.
Authors: Lee Joonhee , Schaefer Craig , Xiang Ning
Published: March 2010

This paper presents an experimental study of low-frequency behavior in coupled volumes. In order to examine low-frequency behavior in coupled volumes, an eighth-scale model of two coupled volumes with an automated high-spatial-resolution scanning system has been developed. The validated scanning system makes it possible to acquire thousands of room impulse responses on a designated planar grid with a fine grid size in the scaled model. The high-spatial-resolution scanning results are used to investigate the characteristics of acoustic wave propagation in both single-space and coupled-volume systems. This paper discusses some design issues relevant to high-quality, high-spatial resolution scanning, to diffusely reflecting interior surfaces, and to variable coupling aperture sizes. Some representative scanning results of sound pressure propagations and sound energy flows will also be demonstrated.
Micro-perforated stretched foils as sound absorbers and barriers.
Authors: Nocke Christian , Hilge Catja , Scherrer Jean-Marc
Published: March 2010

A typical set-up of a micro-perforated sound absorber is a micro-perforated sheet or panel in front of a closed air cavity. The sound absorption coefficient of these set-ups can be easily calculated with a high accuracy according to the well-known approximation of D.-Y. Maa if all defining geometrical parameters (diameter of microperforation, distance between orifices, panel thickness, and air cavity depth) are known. Other applications are freely suspended sails of micro-perforated sheets as well as double layer structures mad of micro-perforated materials. In this contribution measured sound absorption coefficients of different set-ups as well as measurements of level decrease will be presented and discussed. For some of these assemblies no closed calculation model exists so far. Comparisons between computer-based calculations of layered absorber set-ups show good results for some assemblies. Finally room acoustic applications of micro-perforated stretched sheets are shown.
Detecting sequences of calls.
Authors: Mellinger David K.
Published: March 2010

Many sound-producing animals make vocalizations with predictable timing patterns. In some cases, animals produce long, regular sequences of sounds, either for breeding (e.g., many baleen whales) or for foraging (e.g., most toothed whales and dolphins); in other cases, different call types are produced in succession with the intervals between calls following certain timing patterns. Here I describe methods for detecting these timing patterns. Both of these methods operate on a “detection function,” the estimated likelihood at each instant of time that a call is present. Long, regular sequences can be detected using an autocorrelation of the detection function that significantly increases the detectability of sequences compared to single calls. Different call types occurring in irregular but predictable timed patterns can be detected using methods similar to dynamic time warping; again, the detectability of the patterns is notably higher than the detectability of single calls. [Work funded by ONR and the Navy’s Environmental Readiness Division.]
Extracting bone strength information from x-ray image data and applications in clinical research.
Authors: Beck Thomas J.
Published: March 2010

Osteoporosis is a symptomless disease that reduces bone strength so that bones fracture easily, but it is often undiagnosed until fractures occur. Because effective treatments exist, it is important to detect the disease before fractures occur. Current diagnostic methods measure some observable parameter that is statistically correlated with the presence of disease. Most commonly the parameter is a form of bone density although ultrasonic parameters have also been used. Engineers have designed some excellent instruments that measure parameters with high accuracy and precision but even the best methods identify less than half of those at risk of fractures. This is not surprising when discrimination is based how average patients differ from normal rather than on what is actually wrong with them, i.e., reduced bone strength. Mechanical engineering methods can be used to predict bone strength if the material strength and the structural geometry can be measured. Currently there are no reliable non-invasive methods for measuring bone material properties so current mostly x-ray based methods measure structural geometry alone. A review of current methods will be presented together with an overview of what they tell us about osteoporosis as well as what we still need to know.
Bone diagnostics using dual frequency ultrasound measurements.
Authors: Jurvelin Jukka S. , Karjalainen Janne , Riekkinen Ossi , Malo Markus , Isaksson Hanna , Tyräs Juha
Published: March 2010

Diagnosis of osteoporosis is made at skeletal sites composed mainly of trabecular bone. Calcaneus has been the first location for through transmission (TT) ultrasonic measurements of trabecular bone. Similarly as with the DXA, the best prediction of the hip fractures could be obtained by making the measurements at hip. To realize axial pulse-echo (PE) ultrasound measurements, e.g., in hip we have introduced the dual frequency ultrasound (DFUS) technique to minimize the effects of soft tissues overlying the bone and to correct the PE-parameters [Riekkinen et al., Ultrasound Med. Biol. 34, 1703–1708 (2008)]. Based on our experimental measurements at frequencies of 2.25 and 5.0 MHz and finite difference simulations, the DFUS technique detects minor changes in bone density, despite variable composition of soft tissue. For TT-geometry, the composition of the interfering soft tissues may also be solved with the DFUS, e.g., by measuring the reflection from the bone surfaces at both sides of the bone. The measurements with phantom materials indicated that accuracy of TT-parameters, such as broadband ultrasound attenuation, were significantly improved by DFUS. Potentially, the DFUS could also benefit the in vivo TT-measurements of trabecular bone. [Support from Academy of Finland is acknowledged.]
Ultrasonic characterization of cancellous bone using three models of trabecular structure.
Authors: Litniewski Jerzy , Nowicki Andrzej , Wojcik Janusz
Published: March 2010

The semi-empirical scattering models of trabecular bone were developed and examined for their abilities to mimic the frequency dependent backscattering coefficient measured in the cancellous bone. In the simulation of the bone, rf echoes the real properties of the bone and experimental conditions were taken into account. Tree types of trabeculae mimicking scatterers were considered. First, the bone consisted of cylinders with varying thickness (Gamma distributed) within the population was assumed. The next two cases accounted for the contribution of thick and thin trabeculae to the total backscattered signal. The second model assumed existence of two populations of the cylindrical scatterers significantly differing in the average value of Gamma distributed diameters. Finally, the mixed model composed of thick and thin trabeculae modeled, respectively, by cylindrical and spherical scatterers was examined. The last selection resulted from the similarity found between scattering on small sphere and finite cylinder. Calculated echoes demonstrated the usefulness of the mixed model. Frequency dependence of backscattering coefficient agreed well with the experimentally determined dependences. The study also showed that the amplitude histograms calculated using demodulated rf echoes deviate from the Rayleigh distribution when the variation in scatterers’ diameters increase.
Piezoelectret microphones.
Authors: Sessler Gerhard M. , Hillenbrand Joachim
Published: March 2010

Piezoelectret microphones, a recently described new class of electret microphones, are based on the strong piezoelectric effect of internally charged, cellular polymer films. Such piezoelectret films have a large number of internal voids within the polymer. The upper and lower walls of these voids are oppositely charged. Films of this kind, when metallized on both sides, show high-piezoelectric activity and can be directly used as microphones. Recent work on these transducers has concentrated on stacking of piezoelectret films to improve sensitivity, on directional microphones, and on investigations of new film materials with improved charge stability at elevated temperatures. Stacked transducers have sensitivities proportional to the number of piezoelectret layers. With six layers, values of approximately 15 mV/Pa can be achieved. Directivities include omnidirectional, bidirectional, and cardioid patterns as well as dimensional characteristics. The new materials are based on fluoropolymers. These are, as opposed to the originally used polypropylene, not available in suitable cellular form. However, useful films can be made by fusing thin fluorocarbon films such that an array of small air voids is created between the layers. Transducers consisting of charged films of this kind withstand temperatures of 90 °C without significant loss of sensitivity.