bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatially and temporally resolved sonoluminescence from compact bubble clouds.
Authors: Sukovich Jonathan R. , Sampathkumar A. , Holt R. G. , Gaitan D. Felipe
Published: July 2011

Previous investigations of flash duration for single bubble sonoluminescence (SBSL) events in water have shown emission pulse widths on the order of 30–300 ps. The spatial extent of the light-emitting region in SBSL has not been successfully resolved, but it is less than 1 μm. Here we report temporal and spatial observations of light emission from laser-nucleated, compact bubble clouds at high static pressure. Employing high-speed imaging and PMT monitoring, we observe events with durations on the order of 50 ns, whose spatial extent can reach 1 mm in radius. The evolution of event size, spatial uniformity, and intensity will be monitored and compared with parametric data (maximum radius of cloud, outgoing shock velocity, static pressure, and post nucleation time) to discover correlations between light emission and hydrodynamics. [Work supported by the Impulse Devices, Inc.]
Cavitation inception and damage effects in liquid mercury exposed to a high-energy pulsed proton beam.
Authors: Roy Ronald A. , Cleveland Robin O. , Holt R. Glynn , Chitnis Parag V. , Manzi Nicholas J. , Ormonde Christopher E. , Wang Qi , Wendel Mark , Riemer Bernie
Published: July 2011

The Oak Ridge National Laboratory Spallation Neutron Source (SNS) employs a high-energy proton beam incident on a liquid mercury target to generate short bursts of neutrons. Concomitant with neutron production is the rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these bubbles may result in the premature erosion of the target’s steel walls. We report on a multi-pronged effort to both understand and address the problem by (1) inhibiting cavitation inception using bubble injection, (2) analyze cavitation and cavitation cloud dynamics using passive noise diagnostics, and (3) mitigating vessel wall damage using surface modification techniques. [Work supported by the ORNL Spallation Neutron Source, which is managed by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy.]
The effects of fluid compressibility on multibubble cavitation for high-intensity focused ultrasound.
Authors: Sinden David , Stride Eleanor , Saffari Nader
Published: July 2011

In this talk the effects of liquid compressibility and viscosity on cavitation occurring during high-intensity focused ultrasound treatments are discussed. Using techniques from dynamical systems analysis, the criterion for inertial cavitation is formally generalized for multi-bubble models. It is shown that the threshold for inertial cavitation remains independent of the number of bubbles present. It is conjectured that this is because the re-radiated pressure field from any one bubble only has a significant influence on the oscillations of the surrounding bubbles if it collapses inertially. For interacting bubbles the effects of compressibility are analyzed through the inclusion of the appropriate time delays in the bubble interactions. This may result in instability, but it is shown that for values of viscosity relevant to tissue, the system is stable. Instabilities may develop in the full system limiting the ability of a bubble to undergo repetitive bounded oscillations. There are four main mechanisms by which a bubble can become unstable: radial, translational, diffusive, and non-spherical instabilities. In each case it is shown that on including delayed interactions the bubbles are more likely to undergo stable oscillations. The physical implications of these findings are discussed.
Temporal effects with multiple-burst multitone masking.
Authors: Thompson Eric R. , Mason Christine R. , Kidd Gerald
Published: July 2011

Previous work has shown that the detection threshold for a tone-burst target presented simultaneously with a randomized multitone masker that is not affected by increasing the number of identical target-plus-masker bursts. However, when the masker burst is repeated, but the target tone is presented only in alternate bursts, masked detection thresholds may be reduced significantly [Kidd et al., (1994). J. Acoust. Soc. Am. 95(6), 3475–3480]. In the present study, similar conditions were tested, but the masker-alone bursts were presented either ipsilateral or contralateral to the target-plus-masker bursts. In addition, the detectability of a single target burst was measured when the target-plus-masker burst was either preceded or followed by masker-alone bursts. As is typical with random multitone maskers, there were large threshold differences between listeners, but ipsilateral presentation of the alternate masker-alone bursts provided greater benefit than contralateral presentation. Furthermore, some listeners showed no improvement of single-burst detection thresholds with either pre- or postcursors, while others showed a sizable improvement that was similar for both pre- and postcursors. Discussion will focus on possible mechanisms underlying these temporal informational masking effects.
Illusory continuity and masking: Evidence for an illusory tone percept through a notched noise.
Authors: Ciocca Valter , Haywood Nicholas
Published: July 2011

Two experiments measured the illusory continuity of a frequency glide through a noise burst. Expt. 1 used a 2I-2AFC procedure to measure detection of the (target) portion of the frequency glide that overlapped in time with the noise, as a function of noise level. The noise had a frequency notch around the frequency range of the target. The portions of the glide preceding and following the noise (flankers) could be present or absent. Performance at low- and intermediate-noise levels was poorer with present than with absent flankers (at high noise levels, performance was at chance for both conditions). This suggests that listeners either perceptually restored the missing target or that the presence of the flankers resulted in some informational masking of the target. In Exp. 2 listeners rated directly their perception of continuity of the frequency glide for the same flanker conditions of Exp. 1. When the target was absent, continuity ratings increased as noise level increased, and did not differ between intermediate- and high-noise levels. These results suggest that illusory continuity occurred when the noise level was not high enough to mask the target entirely.
Event-related potentials and perception of signals in several types of background noise.
Authors: Billings Curtis J. , Bennett Keri O. , Molis Michelle R. , Leek Marjorie R.
Published: July 2011

Many factors contribute to successful perception of auditory stimuli in noise, including neural encoding in the central auditory system. Physiological measures such as event-related potentials (ERPs) can provide a view of neural encoding that may inform our understanding of listeners’ abilities to perceive signals in the presence of background noise. We set out to determine the effect of stimulus type on neural encoding and perception of signals in noise. Nine young, normal-hearing adults participated. ERPs were recorded (the N1-P2 and P3), and a sentence-in-noise identification task was completed in quiet and in three noise conditions: (1) steady-state speech spectrum noise, (2) interrupted noise, and (3) four-talker babble. Stimuli were presented at a signal-to-noise ratio of −3 dB. Results demonstrated significant effects of noise type on both physiological and behavioral measures with the four-talker babble condition showing the largest decrements in ERP and behavioral measures relative to testing in quiet. In addition, significant correlations were found between ERPs and sentence-in-noise measures. Differential effects of noise type on N1 and P3 ERPs will be discussed and compared with behavioral results. Results suggest that ERPs may be a useful tool for measuring neurophysiological correlates of energetic and informational masking.
Discrimination of stochastic frequency modulation as a predictor of electro-acoustic stimulation benefit.
Authors: Ardoint Marine , Sheft Stanley , Helms-Tillery Kate , Brown Christopher A. , Bacon Sid P.
Published: July 2011

The amount of benefit in speech intelligibility in noise can vary widely for cochlear-implant (CI) users when low-frequency acoustic stimulation is combined with electric stimulation. This variability may, in part, be explained by the listener’s ability to follow fundamental frequency (f0) changes with electric stimulation only: those who benefit the least may be most adept at processing f0 in the electric region. The present study measured the ability of CI users to discriminate stochastic FM patterns when presented acoustically or electrically only. The stimuli were 200-Hz carriers randomly modulated in frequency by 5-Hz lowpass noise. A cued 2IFC procedure was used. In one of the two observation intervals, the cue pattern was repeated; in the other, the modulator was inverted so that the pattern of instantaneous frequency fluctuation mirrored that of the cue pattern at the center frequency. Discrimination thresholds were measured in terms of the FM depth needed to discriminate the deviant from the cue pattern. Additional conditions disrupted FM-to-AM conversion by adding extraneous AM to either the carrier or a noise masker. The discrimination results will be compared to the benefit in speech intelligibility obtained by CI users when presented with low-frequency acoustic cues. [Work supported by NIDCD.]
Native language experience influences the perception of envelope and temporal fine structure cues.
Authors: DeFrancisci Christina , Won Jong Ho , Tremblay Kelly L.
Published: July 2011

This study examined speakers of American English and Korean languages with normal hearing to assess their ability to understand intact as well as vocoded speech. Speech perception abilities were assessed using vowels, consonants, and consonant-nucleus vowel-consonant (CNC) words belonging to the English language. Stimuli were processed using three different methods: (1) intact speech, (2) temporal envelope speech (E), or (3) temporal fine structure (TFS) speech. It was hypothesized that native speakers would perform better than non-native speakers when acoustic information was limited to envelope and TFS cues. Overall, both groups showed a significant effect of stimulus condition with performance being best for the intact condition, followed by the E- and TFS-conditions, respectively. Between groups, American English speakers outperformed the Korean speakers particularly for E, and TFS-conditions, suggesting that a person’s native language experience provides an advantage when acoustic information is limited to E and TFS cues. Moreover, compared to non-native speakers, we speculate that prior language experience enables native speakers to compare E and TFS cues to an existing memory base so they can better use limited acoustic information. [Work supported by NIH NIDCD Grant No. R01-DC007705 and T32-DC000033.]
The frequency following response for dichotic pitch stimuli: No evidence for pitch encoding.
Authors: Gockel Hedwig E. , Carlyon Robert P. , Mehta Anahita , Plack Christopher J.
Published: July 2011

The frequency following response (FFR) was measured for five subjects during the last 350 ms of a 450-ms three-tone complex with a 244-Hz F0. All components were ramped on together in both ears; some were turned off gradually so that in the last 400 ms the harmonics presented were (i) 2+3+4 to the left ear (“mono”), (ii) 2+4 to the left and 3 to the right (“dichotic”), (iii) 2+4 to the left (“2+4”), (iv) 3 right (“3”). Stimuli mono and dichotic had the same pitch. A “vertical” montage (+=Fz, —=C7, ground=mid-forehead) was used. FFR waveforms to alternating-polarity stimuli were averaged for each polarity and added, to enhance envelope, or subtracted, to enhance temporal fine structure information. In both cases, FFR magnitude spectra for the dichotic condition were similar to the sum of the spectra for conditions 2+4 and 3, indicating that information from both ears was present, but lacked peaks at 244 Hz and other distortion products visible for condition mono. Furthermore, in both cases, autocorrelation functions for the dichotic condition were similar to those for 2+4 and dissimilar to those for mono. Thus, the FFR does not reflect similarity of pitch for dichotic and monaural presentation [Work supported by Wellcome Trust Grant No. 088263.]
The potential role of the medial olivocochlear reflex in the estimation of cochlear input-output functions.
Authors: Schumann Madison K. , Strickland Elizabeth A.
Published: July 2011

Research in our laboratory suggests that forward masking may partially be a result of reduced cochlear gain via the medial olivocochlear reflex (MOCR). The MOCR is not activated for approximately 20 ms following elicitor onset (in this case the masker). Growth of masking functions (GOM) and temporal masking curves (TMCs) are forward masking techniques that have been used to estimate the cochlear input-output (I-O) function. Both techniques assume that there is a linear response to a masker approximately an octave below the signal frequency. In the GOM technique, masker threshold is measured as a function of signal level, while in the TMC technique, masker threshold is measured as a function of signal delay from the masker. A short (20-ms) masker was used to estimate I-O functions using the two techniques. Gain should not be reduced in the GOM condition, but could be reduced with delay in the TMC condition. I-O functions estimated using the GOM and TMC techniques diverge at high masker levels. These points correspond to long delays in the TMC technique, where the MOCR may be playing a role. The gain reduction hypothesis and other hypotheses will be explored. [Research Supported by a Grant from NIH(NIDCD) R01 DC008327.]
Loudness matching for enhanced sinusoids.
Authors: Richards Virginia M. , Carreira Eva Maria , Shen Yi
Published: July 2011

When a target sound is masked by a notched masker, thresholds can be lower when a preview of the masker precedes the detection interval. Two experiments were run to determine whether signals “enhanced” by such precursors are also louder. Trials included three intervals. On each trial a random, multi-tone masker was chosen, and presented in each interval. For the loudness matching task, a 1000-Hz target tone was added to the second and third intervals; the level of the test tone in the second interval was adjusted to match the loudness of the standard tone in the third interval. For a standard tone 3–8 dB above threshold, the test tone was adjusted to be approximately 5 dB less intense than the standard, indicating a difference in loudness. For more intense standard levels, this difference decreased. In the second experiment, thresholds for the detection of a tone added to the second or third interval were estimated. Thresholds were approximately 10 dB lower for the second than the third interval. These results indicate that stimuli that induce enhancement (i.e., threshold difference between intervals 2 and 3) also induce increases in loudness, suggesting a role of subjective amplification of the signal for enhancement.
Acoustic characterization of /s/ spectra of adolescents: Moving beyond moments.
Authors: Shadle Christine H. , Koenig Laura L. , Preston Jonathan L.
Published: July 2011

The fricative /s/ is generally acquired later than other speech sounds by children. Spectral moments have been used to quantify comparisons of both children’s and adults’ fricatives, but it is difficult to link moment values to a particular production difference: e.g., the first moment may be relatively low if place is more posterior, the noise source is weaker, or voicing persists into the /s/. This study adapts parameters originally developed for analysis of adults’ fricatives to children’s fricatives. Twelve children (6 boys, 6 girls), 10–15 years old with typical speech, were recorded saying 55–60 words with initial /s/, in singletons or clusters. Multitaper spectra were computed at the beginning, middle and end of each /s/, and parameters were derived from them to capture the main mid-range resonance, relative amplitudes for mid-to-low and mid-to-high ranges, and their change during /s/. Results showed that the mid-to-low-range relative amplitudes increased mid-/s/; the mid-to-high-range relative amplitude decreased; the main peak’s frequency decreased in labialized contexts, all of which occur in adult /s/. One parameter indicated low-frequency spectral variability. These parameters thus capture known acoustic effects of source and filter changes occurring during /s/ and are promising both for measuring developmental changes and assessing misarticulations.
Syllable organization in children’s early American English: Acoustic evidence.
Authors: Thorson Jill C. , Demuth Katherine
Published: July 2011

Children’s early CVC target words are often produced with epenthesis or heavily aspirated release (e.g., cat [kæth]). This has led some to suggest that these are actually produced as two-syllables (CV.C(V)) [Goad and Brannen (2003)]. To evaluate this claim, this study conducted an acoustic investigation of syllable timing in American English 2-year-olds’ production of CVC words. These were compared with productions of disyllabic CV.CV words. For adults, V1 duration and C2-closure duration were expected to be longer in CVC than in CV.CV words [Lehiste (1972); Lisker (1972)]. However, if durations were found to be similar across conditions for children, this might support the claim that children syllabify CVC words as two syllables (CV.C(V)). Participants were three 2-year-olds (mean=2;4) and three adults (mean=23). The stimuli were 4 prerecorded nonce words (/bɑk/, /bɑg/, /bɑkə/, /bɑgə/). Speech productions were sampled at 44 kHz and four repetitions of each word were acoustically analyzed. As predicted, adults showed significantly longer V1 and C2-closure durations in CVC compared to the CV.CV targets (p <0.01). Children showed more variable, non-significant trends (p =0.06). This suggests that 2-year-olds are not treating CVC forms like disyllables, nor are they adult-like in their timing relations. [Work supported by NIH R01HD057606.]
Model-based tracking.
Authors: Sullivan Edmund J.
Published: July 2011

Tracking of an acoustic source in the ocean with a towed array is usually done with a Kalman filter. Although the Kalman filter is a model-based processor, in the case of tracking in the ocean the model is usually the kinematic state of the target itself, i.e., its position and speed. However, this approach is burdened by the necessity of maneuvering the towship in order to obtain two independent bearing measurements. In the method presented here, the signal itself is modeled, including the wavefront curvature and the speed of the towed array. By this means, an increase in the gain and the apparent aperture of the array is obtained, leading to an improvement in the bearing resolution and the ability to obtain an estimate of the range of the source. Experimental results for bearing estimation and wavefront curvature ranging are shown. A framework for the joint estimation of range and bearing using an unscented Kalman filter is then presented in which no towship maneuver is required.
Dependence of Bayesian passive sonar localization performance on signal-to-ratio.
Authors: Pyzdek Andrew T. , Sell Alex W. , Bissinger Brett E. , Culver R. Lee
Published: July 2011

Low frequency acoustic signals propagating in shallow water are strongly affected by interference between multiple paths resulting from boundary interactions. These interactions cause an interference pattern in the transmission loss (TL), which Jemmott [(2010)] successfully used to localize a moving source in range and depth. Jemmott’s Bayesian localization algorithm employs Monte Carlo simulations to build a probability density function (pdf) model for TL based on uncertainty in environmental parameters such as water column depth, sound speed profile, and bathymetry. The TL pdf models are incorporated into the recursive histogram filter as prior pdfs and used to process received signal amplitudes and generate a posterior pdf representing the likelihood of the source location. The localization algorithm has been shown to be robust to known uncertainty in environmental parameters, but other sources of uncertainty such as ambient noise have not been included in the work to date. This paper examines how performance of the algorithm depends on signal-to-noise ratio when the noise is not included in the prior distributions.
Studying killer whale predation in the field: A sound approach to detecting kills.
Authors: Deecke Volker B.
Published: July 2011

Killer whales are top predators in many marine ecosystems and play an important role in regulating marine mammal populations. Studies investigating the feeding ecology of mammal-eating killer whales have been compromised by our inability to consistently identify kills using visual observation. This study aimed to identify predation events using acoustic rather than visual cues. Recordings were made during focal follows of transient killer whales in British Columbia and Alaska using towable hydrophones. During ten follows, kills were confirmed using traditional methods and these recordings were scanned for echolocation clicks, whistles, pulsed calls, and characteristic sounds apparently generated during prey handling. All acoustic analyses were done blind to the behavior context. A discriminant function analysis showed that kills could be identified from the acoustic record with high certainty, primarily because rates of all sound types increased after a kill. Prey-handling sounds proved to be the best indicator that an attack was successful. An analysis of structural parameters of prey-handling sounds and estimate of their source level is also presented. These results show that acoustic cues can improve our ability to detect feeding events. Acoustic monitoring should therefore be incorporated into any field study aiming to quantify predation by mammal-eating killer whales.
The relationship between anthropogenic noise and frequency contours of southern resident killer whale (Orcinus orca) stereotyped vocalizations.
Authors: Tennessen Jennifer B.
Published: July 2011

Marine mammals evolved alongside naturally occurring noise in underwater environments, but recent increases in ocean anthropogenic noise present challenges to effective acoustic communication. Several species of marine mammals have demonstrated compensation strategies to avoid masking, including modifying call duration, frequency, rate, or amplitude. This research explored the relationship between noise and the vocalization behavior of endangered southern resident killer whales threatened in part by vessel traffic. Using extracted frequency contours obtained from recordings made between 2001 and 2007 from bottom-mounted hydrophones, the null hypothesis of no difference in the frequency contours of stereotyped calls across noise classes was tested. The results will be discussed in the context of vocal compensation thresholds in species that communicate using stereotyped calls, and management implications will be suggested.
Three dimensional impedance map analysis of rabbit liver.
Authors: Dapore Alexander J. , Pawlicki Alexander D. , Sarwate Sandhya , O’Brien William D.
Published: July 2011

One challenge of quantitative ultrasound is the identification of the scattering sites in tissue. Three dimensional (3-D) impedance maps (3DZMs) created from a series of histological tissue slide images are a useful tool to identify the scattering structures. 3DZMs are virtual (computational) data sets of real tissue that can be used to study fundamental ultrasonic properties. In this work fatty rabbit liver was chemically fixed and thinly sliced (3 μm) to create a series of H&E histology images. These images were realigned to one another using a registration scheme and pixels were assigned an impedance value to create a 3-D map of acoustic impedance. Through a power spectral analysis of the reconstructed 3-D volume, the effective scatterer diameter was estimated for the tissue using the fluid filled sphere form factor model. The results showed that when weighting the estimation toward smaller scatterer sizes, the effective scatterer diameter was 7.04 ± 1.30 μm. In the actual tissue this diameter corresponds closely to the size of the liver cell nucleus. These results provide encouragement that the reconstructed 3-D volume is an accurate acoustic representation of the tissue, and suggest that the nucleus could be a primary source of scattering in fatty liver. [Work supported by NIH Grant No. CA111289.]
Numerical simulation of focused nonlinear acoustic beams: A Fourier continuation direct solver and comparisons to a paraxial approximation.
Authors: Cleveland Robin O. , Cheung Theresa Y. , Albin Nathan , Bruno Oscar P.
Published: July 2011

A recently developed Fourier-continuation (FC) method is used to develop a numerical algorithm, which can accurately solve the fully nonlinear acoustic vector wave equation for the type of hundred-wavelength domains arising in the field of focused medical ultrasound. The FC nonlinear-ultrasound solver is used to outline the domain of applicability of the widely used Khokhlov–Zabolotskaya–Kuznetsov (KZK) approximation in focused ultrasound particularly in configurations arising in the field of high intensity focused ultrasound (HIFU). Good agreement was found for small-radius transducers; but as the source radius was increased to dimensions equivalent to practical HIFU sources the KZK approximation leads to errors in the location of the predicted focus. Examples for media with multiple scattering centers also show the utility of the FC approach in modeling complex media. In general the FC method produces solutions with significantly reduced discretization requirements over those associated with finite-difference and finite-element methods, and they lead to improvements in computing times by factors of hundreds and to thousands over competing approaches. [Work supported by NSF Grant No. 0835795.]
Acoustic systems for detecting particle impacts in space.
Authors: Corsaro Robert D. , Giovane Frank , Liou Jer-Chyi , Burchell Mark J. , Lagakos Nickolus , Tressler James , Pisacane Vincent
Published: July 2011

This paper briefly describes acoustic systems currently under development for measuring the flux of micrometeorite and orbital debris in space, and detecting damaging impacts when they occur on spacecrafts or habitats. While the particles of interest here are typically small (less than 5-mm diameter) their high speed (greater than 5 km/s) makes an impact quite energetic. At these speeds an impact typically leaves a hole or crater ten times the diameter of the particle, so particles as small as 50 μm can disable a system or create a hazard. The systems described here span a range of purposes. One system is focused on astronaut safety and uses an array of piezoelectric sensors to detect, localize, and assess damage on habitats. Another is focused on scientific data collection and uses a large impact-area diaphragm instrumented with fiber optic sensors for measuring particle size distribution. Other systems use combinations of acoustic and non-acoustic sensors to provide additional information about the nature of the impacting particles. Laboratory tests of each system are described, and the range and limitations of each are briefly discussed. [This work is being supported by the NASA Orbital Debris Office.]
Prediction of sound absorption characteristics of orifice plates with mean flow using the lattice Boltzmann method.
Authors: Habibi Kaveh , Lew Phoi-Tack , Mongeau Luc
Published: July 2011

The purpose of this study was to evaluate the sound absorption characteristics of orifice plates in turbulent mean flows using numerical simulations. The production of vorticity at the orifice edge governs the sound absorption phenomena. The LBM-LES methodology was used to perform detailed numerical simulations of the unsteady turbulent field. The lattice Boltzmann method has several advantages over continuum based CFD methods for situations where the configurations of the duct, the orifice, and the flow structures through or in contact with porous/perforated media are geometrically complex. The absorption coefficient and the impedance of the perforated plate were obtained in a virtual three dimensional (3-D) impedance tube apparatus. Both the mean flow velocity profiles and the acoustic characteristics of a simple circular orifice were found to be in good agreement with available experimental data. The model was then exercised to investigate the acoustic properties of orifices with complex shapes over a range of mean flow velocities.
Transmission of complex sounding signals in human respiratory system.
Authors: Korenbaum Vladimir , Nuzhdenko Anatoly , Tagiltsev Alexander , Kostiv Anatoly , Lopatkin Nikita , Dyachenko Alexander
Published: July 2011

A complexity of respiratory path structure has already caused assumptions on existence of several ways of sound transmission from mouth to chest wall. The objective is a study of these mechanisms. The studied sample included 25 healthy subjects. They breathed with room air, helium-oxygen, and krypton-oxygen gas mixtures which had various sound velocities. Phase manipulated and frequency sweep signals were injected into mouth. Signals transmitted to chest wall sites (bottom part of trachea and basal area of right lung) were recorded by accelerometers. A convolution procedure was carried out. At least two signal arrivals are recognized in each convolution curve recorded above basal area for any gas mixture. One main arrival is recognized above trachea, which times are statistically dependent on gas mixture for all signals. The first arrival times above basal area of lung are also dependent on gas mixture. However, the second arrival times above basal area of lung are independent of gas mixture. Thus the arrival above trachea and the first arrival above basal area of lung, being dependent on filling gas sound velocity, are transmitted through airways lumen at least in part of their path. Alternatively the second arrival recorded above basal area of lung, being independent of filling gas sound velocity, seems to be transmitted through lung parenchyma. [The study was supported by RFBR grant 09-08-00105.]
High speed electronic speckle pattern interferometry as a method for studying the strike on a steelpan.
Authors: Morrison Andrew C. , Moore Thomas R. , Zietlow Daniel
Published: July 2011

Electronic speckle pattern interferometry (ESPI) is a useful method for characterizing the operating deflection shapes and modes of vibration of musical instruments. Using ESPI in conjunction with a high-speed camera, capable of capturing images at rates of several thousand frames per second, allows for time-resolved examinations of transient motion. High-speed ESPI movies of note strikes of a low-tenor (also called a soprano) steelpan were acquired while simultaneously recording the sound of the strike. The comparison of the time-resolved interferometry data with the analysis of the sound recordings allows for insights into the evolution of coupling between note areas.
Vibration modes of clarinet reeds via digital electronic holography.
Authors: Stetson Karl A.
Published: July 2011

Discovered in 1964, holographic interferometry has provided vibration and deformation analysis of structures through the 1970s and into the 1980s. In the late 1980s, photographic holography gave way to digital electronic holography this greatly advanced its capabilities by making it possible not only to display interferograms in real time, but also to reduce fringe patterns to numerical data. This technology is widely used for verification of vibration modes of such engineering components as jet engine turbine blades. Holography has also been used to study the vibration modes of string instruments since the late 1960s. This paper applies it to the study of clarinet reeds. Although the vibration amplitude of such reeds when played is many times the level that can be studied holographically, examination of their basic vibration modes offers some insight into how they may function. A comparison is shown of the modes a wet cane reed to several synthetic reeds whose fundamental modes are shown to lie at lower frequencies than an equivalent cane reed. The presentation will conclude with some suggestions for studies of reed profiles and for measurement of reed motion under playing conditions.
Measurement of mode shapes of musical instruments using a scanning laser Doppler vibrometer.
Authors: Huber Thomas M.
Published: July 2011

In studying musical instruments and other vibrating systems, optical methods, such as ESPI holography and laser vibrometery, have allowed non-contact measurements of operating deflection shapes. This talk will focus on the principles and operation of a scanning laser Doppler vibrometer system, as well as its application for measuring vibration of musical instruments. Examples will be presented for instruments including guitars and organ reed pipes, which show the capabilities of a Polytec PSV-400 scanning vibrometer system to measure steady-state deflection shapes at resonance frequencies of the system. Also demonstrated will be measurements of the vibration of the face of a guitar during the attack transient.
Optical methods in stringed instrument testing.
Authors: French Mark , Moore Haley
Published: July 2011

Stringed instruments present an experimental challenge for several reasons. Radiated sound is a strong function of dynamic response, so particularly accurate measurements of structural and acoustic resonant frequencies are desirable. However, the structures tend to be very light and sensitive to the additional mass of contacting sensors. Thus, optical methods are attractive. The ready availability of lasers, inexpensive digital cameras, and powerful, inexpensive computers has made optical testing practical. As a result, a range of methods has been applied to musical instruments. There are many ways to organize the methods, but an attractive one is whether they require coherent light for interference effects. A hierarchy of methods is presented along with representative results. The simplest methods simply track motion of a reflected beam across an optical sensor. Coherent methods start with laser vibrometry and move through holography and speckle pattern interferometry. We pay particular attention to an particular application of laser vibrometry and to a low cost speckle pattern interferometer.
Acoustic effects of holes on commercial cymbals.
Authors: Peaden Brooke R. , Worland Randy
Published: July 2011

In recent years, several cymbal companies have begun manufacturing cymbals with holes cut into them. The 10 -in. cymbal used in this study (Sabian Ozone Splash) contains six symmetrically placed 1.5 in. diameter holes. Electronic speckle pattern interferometry (ESPI) has been used to collect mode shape and frequency data on brass plates and cymbals containing holes of various sizes. Data taken on a brass plate show that a single hole may cause mode frequencies to increase or decrease depending on the size and location of the hole relative to the modal pattern. As a hole can be treated as a region of both lower mass and lower stiffness, these competing frequency effects are to be expected. To illustrate the effect of the six holes on the Ozone cymbal, ESPI data are presented on a standard 10-in. Sabian splash cymbal (without holes) as six holes are added in a series of increasing diameters until the geometry of the Ozone cymbal is matched.
Adapting noise measurement and modeling practices to meet legislative and policy mandates for National Park management.
Authors: Fristrup Kurt M.
Published: July 2011

Historical community noise studies focused on exposures corresponding to maximum tolerable annoyance and potential health risks. These criteria should rarely be pertinent for National Parks, but applicable knowledge and tools were developed by these studies. A-weighted measurements integrate sound energy across the audible spectrum to account for properties of human hearing. To improve the utility of A-weighted measurements, NPS is investigating band-limited dB(A) measures to exclude natural environmental sounds that have no bearing on the effects of anthropogenic noise. Leq metrics were shown to be reasonable for integrating time histories to predict human responses to noise exposure. NPS utilizes measurements of audibility to parse this measure into the extent of noise-free conditions and the Leq value when noise is audible. This approach distinguishes situations with chronic exposure to modest levels of noise from very infrequent exposures to loud events. Several noise models have been developed to support community noise management. These are used in park settings to model the kinds of individual noise events that can occur (a type of vehicle on a specific route). Interactive noise mapping tools have been developed to compute aggregate exposure from collections of many such events under different planning scenarios.
Environmental noise measurements at Mount Rushmore National Memorial.
Authors: Schomer Paul
Published: July 2011

Assessing noise in national parks remains a subject of research and study for two general problem areas: the reaction to noise by park visitors and the effects of noise on wildlife. Traditional methods for environmental noise assessment such as methods to assess the effects of airport noise on residential communities are inappropriate and inadequate for the National Park issues, and Schomer and Stanley (2009) developed a research plan to gauge the sound quality of a hike, not annoyance. The goal of this research is to develop methods to assess the sound quality of different park soundscapes by being able to rate the acoustical experience of park visitors. This report concentrates on physical measurements of the acoustic environment. Our approach for the measurements was to select a trail that was used regularly, but not particularly heavily, that had regular, distinct anthropogenic noise, and that was readily accessible. This paper provides an analysis of the acoustical measurements. In particular, it provides an analysis of the data collected by the 20 fixed monitors, an analysis of the data collected by the mobile monitor, and an analysis of the GPS data used to establish the mobile monitor position as a function of time.
A pilot survey of visitor perception of sounds along a trail.
Authors: Pamidighantam Arnav R. , Schomer Paul D.
Published: July 2011

A pilot survey was conducted to determine the perception of noise by visitors along a hike at a national park by asking visitors to take a written survey on all or a large portion of predetermined route. The visitors were asked to stop at their discretion, several times, and rate the acceptability and their interpretation of the noises heard at the stop on a nine point bipolar scale. These questions were asked for a wide variety of sounds that may be heard on a trail. Also, a cumulative question was asked in order to rate the acceptability and personal interpretation of noise at each stop as well as the hike as a whole. Analysis of the completed surveys was done to establish the effectiveness of the survey and any changes that would make the survey more user-friendly. This paper discusses the effectiveness and user-friendliness of the survey as well as the methods determined to increase these characteristics in the hope of better understanding how the visitor perception of a trail is determined by the noises along the trail.
Shock-controlled bubble cloud dynamics and light emission.
Authors: Holt R. Glynn , Anderson Phillip A. , Sampathkumar Ashwinkumar , Sukovich Jonathan R. , Gaitan D. Felipe
Published: July 2011

Cavitation bubble collapse can generate intense concentrations of mechanical energy, sufficient to erode even the hardest metals and to generate light emissions visible to the naked eye. In this talk we describe cavitation bubble cloud experiments carried out in spherical resonators at ambient and acoustic pressures up to 30 MPa. Key to our system is the ability to nucleate with temporal and spatial controls, which we achieve using dielectric breakdown in water from pulsed focused laser beams. Our observations show that the cloud dynamics are controlled by the repetitive emission of shock waves, which propagate outward from the inertial cloud collapse, reflect off of the sphere wall, and then converge on the resonator center. Shock convergence phenomena and light emission from compact cloud collapse will be discussed. [Work supported by the Impulse Devices, Inc.]
Characteristics of high-quality factor resonators operating at high static pressures.
Authors: Gaitan D. Felipe , Gutierrez Joel , Pishchalnikov Yuri A. , Coffin Michael , Tardif Henry
Published: July 2011

Cavitation collapse can generate intense concentrations of mechanical energy, sufficient to erode even the hardest metals and to generate light emissions visible to the naked eye, e.g., single bubble sonoluminescence. We describe a high-quality factor, spherical resonator capable of achieving acoustic cavitation at ambient pressures in excess of 30 MPa. In this presentation, the dynamics of the resonator and the cavitation in general will be discussed, e.g., driver configuration, quality factor, resonance modes, power and pressure amplitude threshold for cavitation, etc., as a function of static pressure, as well as other parameters. [Funded and directed by Impulse Devices, Inc., ACPT Contract W9113M-07-C-0178.]
Modeling time delay in clusters of interacting bubbles.
Authors: Thomas Derek C. , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: July 2011

Modeling the dynamics of large clusters of interacting bubbles requires that the effects of fluid compressibility be taken into account. Compressibility manifests itself through radiation damping and bubble-bubble interactions due to time delays associated with the finite sound speed. The time delays convert the dynamical equations for interacting bubbles in an incompressible fluid from a system of nonlinear ordinary differential equations to one of delay differential equations (DDEs). Special care must be taken when integrating DDEs numerically to maintain acceptable bounds on errors. The dynamical equations determined to be most suitable for solving as DDEs were obtained using Hamiltonian mechanics [Ilinskii et al., J. Acoust. Soc. Am. 121, 786 (2007)]. These first-order differential equations were augmented to include time delays in the bubble interaction terms and then solved numerically using a sixth-order Runge–Kutta method with a continuous interpolant (DDE_SOLVER). The same equations were also solved without the time delays but with correction terms that account for mutual radiation damping. Comparison of the results reveals the importance of time delay in bubble-bubble interactions as a function of the size and density of a bubble cluster. [Work supported by the ARL:UT McKinney Fellowship in Acoustics and NIH Grant No. DK070618.]
Shock-driven growth of bubble clouds.
Authors: Anderson Phillip , Sampathkumar A. , Holt R. G.
Published: July 2011

Laser-nucleated bubble clouds in a high-pressure spherical resonator have previously been reported to develop into tight clusters after many acoustic cycles. The formation of these organized clusters is largely driven by the reconvergence of shocks from earlier cloud collapses. Highly temporally (40 Mfps) and spatially (3 μm/pixel) resolved images reveal that the expansion of the shock-nucleated clusters is initially very fast (> 8 km/s), much faster than the shocks themselves. However, this explosive growth of the cluster does not begin until hundreds of nanoseconds after the shock passes, and so the cluster never surpasses the shock itself. The phase diagrams of the cluster and shocks are mapped out and the shock-driven nucleation is discussed. [Work supported by the Impulse Devices, Inc.]
Neural sensitivity to interaural level differences determines virtual acoustic space minimum audible angles for single neurons in the lateral superior olive.
Authors: Tollin Daniel J.
Published: July 2011

The minimum audible angle (MAA), the smallest angle separating two sound sources that can be reliably discriminated, is a psychophysical measure of spatial acuity. In humans and cats, MAAs for tone and noise stimuli range from 1–5 deg. For high-frequency (>1.5 kHz) tones the predominant cue for azimuth is the interaural level difference (ILD). Neurophysiologically, ILDs are first encoded in the lateral superior olive (LSO). Here, we examined the ability of LSO neurons in cats to signal changes in the azimuth of noise sources. Using measurements of head related transfer functions, the virtual acoustic space technique was used to manipulate source azimuth in the physiological experiments. For each neuron detection theory was used to compute the smallest increment in azimuth necessary to discriminate that change based on discharge rate and response variability. Minimum neural MAAs were 2.3 deg for midline sources (median = 4.5 deg, n = 32 neurons). The good neural acuity for spatial location will be explained in terms of the changes in the acoustic ILD cue with changes in source location along with the underlying sensitivity of the LSO neurons to the ILD cue. LSO neurons can signal changes in sound azimuth that match or exceeded behavioral capabilities. [NIH DC006865.]
Empirical and theoretical findings concerning how interaural intensitive disparities affect lateralization for high- versus low -frequency stimuli.
Authors: Bernstein Leslie , Trahiotis Constantine
Published: July 2011

This presentation concerns empirical and theoretical findings concerning the potency of interaural intensitive disparities (IIDs) at low versus high spectral frequencies. In one context, an acoustic pointing task was used to measure how IIDs affect extents of laterality. Laterality was measured for 4-kHz-centered stimuli with reinforcing or opposing combinations of IIDs and interaural temporal disparities (ITDs). The goal was to assess whether IIDs act as scalars or “weights” within the putative “binaural display” at high spectral frequencies (where the envelopes convey ITD-information) as they have been repeatedly shown to operate at low spectral frequencies (where the waveforms convey ITD-information). They do. The data were accounted for via an augmentation of the cross-correlation-based “position-variable” modeling approach developed by Stern and Shear [J. Acoust. Soc. Am. 100, 2278–2288 (1996)] to account for ITD-based lateralization at low spectral frequencies. In a second context, laterality produced by IIDs (ITD=0) was measured for stimuli centered at either 4 kHz or 500 Hz. The novel finding was that IIDs consistently produced larger extents of laterality at 4 kHz than they did at 500 Hz. [Work supported by research Grant No. NIH DC-04147 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.]