bluuebunny/crossref_metadata_2025 huggingface dataset:
Soundscape analysis standardization, a proposed lexicon of descriptors for local expert interviews.
Authors: Brooks Bennett M.
Published: July 2011

Soundscape analysis is a powerful technique that can be applied to the practical development of quality sonic environments. The combination of physical measurements and the corresponding perceptual responses to a sound climate provides illumination otherwise unavailable to development project designers. Interviews of local experts, residents, and other users of the environment can yield insights into both personal reactions and universal observations. These can include the identification of sound sources of which the project developers were, until then, unaware. The success of a new project may depend on the lessons learned from previous developments. The standardization of interview techniques then becomes increasingly important. Can a standard lexicon of terms for local expert interviews be developed? The answer to this open question is informed by the contributions of psychoacoustic and perceptual evaluations the subtleties of linguistics, the circumstances of the environment under observation, and the persons involved. An interview questionnaire lexicon of descriptors for field use is proposed, based on the experiences of recent project interviews, the results of ASA soundscape workshops, and other sources.
Soundscape : Recording the infinite.
Authors: Case Alex U.
Published: July 2011

The essential elements of a soundscape are far from defined, but accurately documenting an ensemble of identifiable sound sources across a multitude of spaces is sure to require a wide dynamic range, full frequency response, and the successful capture of the perceptual cues for assessing localization, distance, source size, spaciousness, envelopment, etc. More than 1 century of research and development in sound, recording techniques and technologies can inform soundscape standardization and implementation. The challenge is not only to capture and analyze, but also to reproduce, recreate, and even pre-create the soundscape in an alternative environment. Music, film, and game sound recordists have an advanced set of capabilities for creating meaningful, evocative works of art—both fiction and non-fiction—from the relative comfort, predictability, and convenience of the recording studio production environment. An ambitious attempt to export the highest quality studio capabilities to the field is presented. A mobile, multichannel, high definition, digital recording apparatus has been designed and field-tested, and the most important insights, caveats, accomplishments, and failures so far are detailed.
Individual soundwalk methodology for assessment of urban soundscape.
Authors: Hong Joo Young , Lee Pyoung Jik , Jeon Jin Yong
Published: July 2011

This paper describes the individual soundwalk as a methodology for assessment of urban soundscapes. Compared with previous studies which have adopted soundwalk methodology, the individual soundwalk has significant differences in evaluation and analysis procedure. In the present study, soundwalks are performed individually, and subjects are asked to select the sites which produce a negative or positive impression while walking within a specific area. At each site, the subjects evaluate the soundscape perception using a questionnaire and describe why the urban soundscape is perceived favorably or unfavorably in terms of contexts. Furthermore, audio-visual recordings are carried out and environmental factors such as day light, temperature, and humidity were measured simultaneously. From various responses of the subjects, the dominant contexts that influence the soundscape perception are derived, and design elements of urban spaces are extracted through qualitative analysis.
Effects of contexts on perception of urban soundscape.
Authors: Jeon Jin Yong , Lee Pyoung Jik , Hong Joo Youn
Published: July 2011

In the present study, the effects of contexts on soundscape perception in urban space are investigated through social surveys and soundwalks. Acoustic comfort, visual image, day lighting, olfactory, and reverberance are utilized as main contexts which may have an effect on the soundscape perception. Preference for contexts and overall impressions are evaluated by using an 11-point. numerical scale in the social survey and soundwalk. For qualitative analysis, semantic differential tests are performed in the social survey while subjects are asked to describe their own impressions during soundwalks. The results show that urban soundscapes can be characterized by soundmarks, and soundscape perceptions are dominated by acoustic comfort, visual image, and day lighting. However, it is found that the subjective rating of reverberance in urban spaces is not appropriate. The categories extracted from the qualitative analysis reveal that spatial sensations such as openness and density emerge as primary contexts for soundscape perception.
Modelling subjective evaluation of soundscape: Towards soundscape standardization.
Authors: Kang Jian , Yu Lei
Published: July 2011

Based on a series of large scale surveys, this paper first analyzes the effects of social, demographical, and behavioral factors as well as long-term sound experience on the subjective evaluation of soundscape in urban open public spaces. Te paper then explores the feasibility of using computer-based artificial neural network to build models for predicting the soundscape quality evaluation of potential users in urban open spaces at the design stage. It has been shown that for both subjective sound level and acoustic comfort evaluation, a general model for all the case study sites is less feasible due to the complex physical and social environments in urban open spaces, models based on individual case study sites perform well but the application range is limited, and specific models for certain types of location/function would be reliable and practical. It is expected that such a model framework would be useful for the soundscape standardization, in terms of factors to be considered, for example.
Measurement of preserved structures as a resource for historic soundscape reconstruction.
Authors: Reuter Eric
Published: July 2011

Acoustical attributes of preserved historic structures have been measured using contemporary techniques and metrics. These include outdoor-to-indoor and indoor-to-indoor impulse response and noise reduction measurements. Combined, these measurements allow for simulation, both quantitative and qualitative, of the indoor soundscapes of the past. These data will be presented, along with audio examples of historical noise sources, as experienced from indoors.
Augmenting probabilistic inversion for whale localization with propagation models.
Authors: Frank Scott D. , Ferris Aaron N.
Published: July 2011

Tracking of marine mammals is important for the evaluation of species geographic range and for investigating the relationship between vocalization and behavior patterns. The use of ocean bottom seismic and hydrophone arrays is gaining interest in marine mammal studies due to their relatively long deployments (6–12 months) and low environmental impact. A Bayesian inversion method generates a probability density function for the source location by comparing travel time differences observed at ocean bottom arrays with those from a theoretical model. The method also accounts for uncertainty arising from difficulties in evaluating arrival times, instrument location, or choice of theoretical model. This method can be augmented with a similar comparison of observed arrival amplitudes and transmission loss results from parabolic equation propagation modeling. Due to acoustic convergence zones, the amplitude data may specifically contain information regarding the source’s range from the array. Uncertainty in the propagation modeling can also be included in the inversion. Results from travel-time only inversions and those that include propagation modeling results will be presented for comparison.
Vulnerable atherosclerotic plaque in human artery sections and apolipoprotein E-deficient mouse aortas.
Authors: Anastasiadis Pavlos , Allen John S.
Published: July 2011

Atherosclerosis is a systemic disease developing over the course of many years. Vulnerable atherosclerotic lesions may rupture without warning resulting in acute cardiac infarction. An outstanding need exists for accurately predicting the plaque sites most prone to rupture. However, few studies have investigated the mechanical properties of plaque in nonfixated human samples or the properties as a function of plaque development in animal models. The size and fragility of plaque in mouse models limit standard mechanical measurement techniques. Elastic and mechanical parameters of atherosclerotic lesions were determined by scanning acoustic microscopy at center frequencies of 50 and 100 MHz. The comparative study included human femoral, aortic and coronary sections, as well as aortic sections from normal and apolipoprotein E-deficient mice. Nonfixated samples were investigated and subsequently fixated for complementary fluorescence microscopy imaging with atherosclerosis-related biological markers. Elastic parameters show significant differences between normal and diseased tissues. Ultrasound velocities across the intima, media, and adventitia of the artery cross-sections vary in the range from 1626 ± 24, 1680 ± 20, and 1640 ± 18 m/s, respectively. Moreover, the plaque lesions show a higher velocity of 1890 ± 27 m/s. [Research supported by NIH/NCRR Grant No. 2G12RR0030161-21.]
Smoking effects on cyclic variation of harmonic echogenicity in carotid artery.
Authors: Li Ying , Bok Tae-Hoon , Paeng Dong-Guk , Choi Min-Joo , Yang Jeong-Hwa
Published: July 2011

The dynamic changes of echogenicity in common carotid artery was observed from coded harmonic images by GE ultrasound systems. The observed variation in echogenicity was related with the dynamic change of red blood cell (RBC) aggregation during a cardiac cycle. In this research, the cyclic variation in echogenicity (CVE) was observed in the harmonic images of the carotid artery from 28 smokers before and after smoking using a GE Voluson e ultrasound system. The amplitude of CVE (Acve) was significantly increased after smoking in the heavy smokers compared with the one in light smokers (4.98±4.26 vs −0.3±3.01, P<0.05). Acve was also compared among 17 nonsmokers, 11 light smokers, and 17 heavy smokers. The effects of tissue attenuation on Acve were compensated with body mass index (BMI). Compensated Acve is significantly higher in heavy smokers and light smokers compared with that in nonsmokers (36.7±9.5 and 35.1±5.1 vs 29.3±7.9, P<0.05). The effects of smoking on CVE were discussed with hemodynamic and hematological changes caused by smoking. The increased RBC aggregation due to the flow acceleration and hematological changes were suggested as interpretations. It demonstrated the potential of Acve to estimate RBC aggregation in vivo. [Work supported by Grant No. NRF-2010-0014004.]
Synthesize rugged acoustic sensors using poly(vinylidene fluoride)/carbon nanotube composite films.
Authors: Zhang Qin , Adebisi Rasheed A. , Gladden Joseph R.
Published: July 2011

A procedure is proposed to prepare poly(vinylidene fluoride) (PVDF)/multi-walled carbon nanotube (MWCNT) nanocomposite thin films with improved mechanical properties compared to the pure PVDF films. The PVDF/MWCNT mixture was formed using solution blending and the ultrasonic dispersion method and then spin-coated on a rotating glass substrate to produce films nearly 20 μm thick. The mechanical properties of the resulting films were examined and compared to the pure PVDF films through the mechanical tensile tests. The elastic modulus and fracture toughness after adding MWCNTs into PVDF will be discussed. These thin films are to be used to fabricate highly rugged acoustic sensors that will have the ability to withstand very high impulsive acceleration and have enough flexibility to be applied to irregular surfaces such as a helmet or clothing. The piezoelectric response of these films will also be discussed. [Work supported by the U.S. Army, contract # W15QKN-09-C-9999.]
Low-cost, novel teaching tools for liberal-arts acoustics courses.
Authors: Spoor Philip S.
Published: July 2011

Several teaching tools and methods are demonstrated, which have proven especially useful for teaching acoustics to students with a liberal-arts background. The author developed these tools over 5 years of teaching the acoustics of music and speech at the Pennsylvania State University. The class had no prerequisites, and would often include some students with a strong physics or math background, some with a strong musical background, some with both, and some with neither. The methods discussed in this presentation have been found to keep the concepts accessible yet interesting to students of widely varying backrounds. These methods include teaching the students to do Fourier analysis by ear on common sounds, therefore teaching themselves how a complex tone is comprised of simpler pieces. Another method involves making a Helmholtz resonator the centerpiece of an auditory puzzle, using ordinary (and inexpensive) objects. The puzzle is simple enough that anyone trained in acoustics gets it right away; but even many trained scientists without an acoustics background are stumped.
A vibrotactile music system based on sensory substitution.
Authors: Egloff Deborah , Braasch Jonas , Robinson Philip , Van Nort Doug , Krueger Ted
Published: July 2011

The idea of the project reported here was to design a system that builds on touch to enable people with severe hearing impairments to “listen” to music through a process called sensory substitution. The goal was to transform the auditory parameter space into one that is adequate for haptic perception. The approach reported here builds on (i) the design of a haptic display, a tabletop device with 8–24 actuators that can be driven individually, (ii) machine learning algorithms, and (iii) a psychophysical study to determine which music cues can be perceived through touch. The latter was necessary because vibrotactile perception is not yet well understood in the context of music perception. The double-blind study analyzes how vibrotactile stimuli contribute to the perception, cognition, and distinction of sounds in human participants who have been trained versus those who have not. In order to ensure that normal-hearing participants could not hear sounds radiated from the haptic display, sound isolating headphones were used to playback pink noise during the experiment.
Probing multibubble cavitation fields under different experimental conditions.
Authors: Ashokkumar Muthupandian
Published: July 2011

The understanding and control of the spatial distribution and the type of cavitation bubbles are crucial for the efficient use of cavitation bubbles in these applications. A semi-quantitative comparison of the spatial distribution of the cavitation activity has been carried out using the images of sonoluminescence, sonophotoluminescence, and sonochemiluminescence at various ultrasound frequencies and at various acoustic amplitudes. The sonochemically active cavitation zones have been found to be much larger than the sonoluminescence cavitation zones. Also, the sonochemically active bubbles have been observed at relatively lower acoustic amplitudes than that required for sonoluminescence bubbles to appear. The acoustic power required for the observation of the initial cavitation bubbles increases with an increase in the ultrasound frequency. These observations highlight the complexities involved in acoustic cavitation. Multibubble sonoluminescence-based experimental technique has also been used for the detection and the control of type of cavitation at low and high ultrasound frequencies.
The effect of static pressure on the inertial cavitation threshold and collapse strength.
Authors: Bader Kenneth B. , Raymong Jason L. , Mobley Joel , Church Charles C. , Gaitan D. Felipe
Published: July 2011

The conditions within an inertially collapsing bubble are known to produce high temperatures and pressures. Previous investigators have proposed various mechanisms for driving the collapse in order to maximize the energy density of the bubble’s contents. Working in fluids at high static pressures (up to 30 MPa) has shown some promising results. Preliminary data indicate that the strength of the collapse scales with the static pressure in the fluid. We report here the results of a series of rigorous experiments designed to better define this relation at the threshold of inertial cavitation. The hydrostatic pressure dependence of the inertial cavitation threshold in ultrapure water was measured in a radially symmetric standing wave field in a spherical resonator driven at 26 kHz. At this threshold, the collapse strength will be reported in terms of the resulting photon radiance below 400 nm and the relative shock wave amplitude. These experimental results will be compared to predictions of collapse strength. [Work supported by Impulse Devices, Inc.]
Dynamics of tandem bubble interaction in a microfluidic channel.
Authors: Yuan Fang , Sankin Georgy , Zhong Pei
Published: July 2011

The dynamics of tandem bubble interaction in a microfluidic channel (800 × 25 μm2, W × H) are investigated using high-speed photography with resultant fluid motion characterized by particle imaging velocimetry. Single or tandem bubble is produced reliably via laser absorption by micron-sized gold dots (6 μm in diameter with 40 μm in separation distance) coated on a glass surface of the microfluidic channel. Using two pulsed Nd:YAG lasers at λ = 1064 nm and about 10 μJ/pulse, the dynamics of tandem bubble interaction (individual maximum bubble diameter of 50 μm with a corresponding collapse time of 5.7 μs) are examined at different phase delays. In close proximity (γ = 0.8), the tandem bubble interacts strongly with each other leading to asymmetric deformation of the bubble walls and jet formation, as well as the production of two pairs of vortices in the surrounding fluid rotating in opposite directions. The direction and speed of the jet (up to 95 m/s), as well as the orientation and strength of the vortices can be varied by adjusting the phase delay.
Deformation and interaction of cylindrical bubbles.
Authors: Ilinskii Yurii A. , Hay Todd A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: July 2011

Experiments performed by Sankin et al. [Phys. Rev. Lett. 105, 078101 (2010)] demonstrate shape deformation of two coupled laser-generated bubbles confined between parallel surfaces. Due to their confinement, their motion is predominantly two-dimensional. It is known that any change in the volume of a cylindrical bubble in an unbounded incompressible fluid is prohibited because the effective mass loading is infinite. The natural frequency of a cylindrical bubble in its pure radial pulsation mode is correspondingly zero, and it becomes finite only if the surrounding fluid is either compressible or of limited extent. Because the higher-order modes of an oscillating cylindrical bubble involve no change in volume, their natural frequencies remain finite in an infinite incompressible fluid. Using the approach developed to model shape deformation of two coupled spherical bubbles [Kurihara et al., J. Acoust. Soc. Am. 127, 1760 (2010)] we obtained a set of coupled second-order ordinary differential equations in two dimensions describing the pulsation, translation, and deformation of coupled cylindrical bubbles. The presentation will focus on the deformation of a single cylindrical bubble, and the interaction and deformation of two cylindrical bubbles. [Work supported by NIH Grant Nos. DK070618 and EB011603.]
Discrimination of stimulus variance.
Authors: Viemeister Neal F. , Stellmack Mark A. , Byrne Andrew J.
Published: July 2011

In real-world settings, auditory signals such as speech are highly variable and differ across occurrences and sources. The question addressed is our sensitivity to such differences in global stimulus variability. In a variance discrimination task, the stimuli were sequences of five 100-ms tone pulses separated by 30 ms. The frequency of each tone was sampled independently from a probability distribution that was Gaussian on logarithmic frequency. In the non-signal interval of the 2IFC task, the sampled distribution had a mean frequency Mf and variance Vf. In the signal interval, the variance of the sequence was Vf + ΔVf. The task was to choose the interval with the larger variance; feedback was provided. To restrict the use of decision strategies, Mf was randomly chosen for each presentation(M̄ f=2 kHz). Psychometric functions |P(C) vs ΔVf| were obtained for various values of Vf , and overall performance was poorer than that of an ideal observer. However, like the ideal, Weber’s law behavior was observed: Constant ΔVf / Vf yielded the same performance. Degrading the Ideal with a fixed frequency resolution noise and a multiplicative computational noise provides an excellent account of the real data. [Work supported by NIDCD DC00683.]
Speech perception in steady and amplitude modulated band-pass noise.
Authors: Jin Su-Hyun , Nie Yingjiu , Nelson Peggy
Published: July 2011

The purpose of the current study was to examine the effects of temporal and spectral interferences on sentence recognition for cochlear (CI) implant listeners. Nie and Nelson (2010) investigated vocoded speech perception in amplitude-modulated band-pass noises in order to assess young normal-hearing (NH) listeners’ speech understanding through cochlear implant simulations. They reported that while the spectra of the noise bands affected vocoder speech perception, there was no significant effect of the noise AM rate on performance, indicating spectral but not temporal interference. As a follow-up, young CI listeners with various devices and processing strategies participated in the current study. IEEE sentences and white noise were divided into 16 bands, and band-pass noise maskers were formed from varying combinations of 4–6 adjacent bands. The spectra of the maskers relative to the spectra of speech were set to be one of the following: completely overlapping, partially overlapping or completely separate from the speech. Noise was sinusoidally modulated at three rates: 4, 16, and 32 Hz. It is hypothesized that sentence recognition scores for CI listeners are affected by both spectral and temporal characteristics of the noise, which is different from the performance for NH listeners reported previously.
Pitch perception for sequences of pulses alternating different resonance scales.
Authors: Tsuzaki Minoru , Matui Toshie , Takeshima Chihiro , Irino Toshio
Published: July 2011

Vowels are produced as a sequence of vocal tract impulse responses which are periodically excited by glottal pulses. Each impulse response reflects the shape and the size of the vocal tract. The size, i.e., the resonance scale, is kept almost constant in the normal speech sounds. It has been found that we can sensitively “hear” such size variations in speech and that the size can be a cue to identify the sound source, i.e., the talker. What do we perceive if impulse responses with two different resonance scales are alternatively repeated. Do we perceive an intermediate sized talker speaking the same pitch as the original? Do we perceive two speech streams of the different sized talkers with the half pitch? By answering these questions, we could clarify the auditory mechanisms for detecting size, periodicity, and resonance. The test stimuli were synthesized whose consecutive glottal pulses were alternated between two resonance scales with several degrees. Pitch matching experiments were performed where the listeners could adjust the fundamental frequency of the comparison stimuli whose each pulse had an identical scale factor. To a certain degree of the resonance scale deviation, the subjective pitch appeared to match the original pitch. If the scale deviation exceeded that limit, the pitch went down by an octave.
A comparison between contralateral suppression in cochlear microphonics and distortion product otoacoustic emissions.
Authors: Najem Fadi , Kaf Wafaa , DiSarno Neil , Ferraro John
Published: July 2011

This study compares the contralateral suppressive effect of the auditory efferent system on cochlear microphonics versus distortion-product OAEs (DPOAEs) in order to identify the potential versus the mechanical changes of the outer hair cells. This was achieved by recording the CM and DPOAEs from the right ear of 16 normal-hearing young female adults with and without broad band noise (BBN) in the left ears. DPOAEs were recorded at 0.5, 2, and 4 kHz F2 frequencies, and at 0.5 and 2 kHz tone bursts and clicks for CM using condensation and rarefaction polarity. Results revealed that both DPOAEs and CM recordings showed suppression and enhancement effects of BBN, but there were no statistically significant differences within each recording (with-without BBN) and between recordings (CM versus DPOAEs) (P = 0.923 at 0.5 kHz, P = 0.858 at 2 kHz, and P = 0.332 at 4 kHz or clicks). This could be related to the small effect and the lack of sensitive enough equipment. In general, larger effect was observed at 0.5 kHz in DPOAEs, but at 2 kHz in CM. Interestingly, when the stimulus polarity of the CM was changed from condensation to rarefaction at 2 kHz in the presence of BBN, six participants showed CM recordings that changed from suppression to enhancement or vice versa, suggesting a possible relationship.
Does reduction in cochlear gain explain the overshoot effect?
Authors: Fletcher Mark , de Boer Jessica , Krumbholz Katrin
Published: July 2011

Under certain conditions, detection of a masked tone is improved by a preceding sound (a precursor); this is the overshoot effect. Despite over half a century of research, its underlying mechanisms remain unknown. A popular hypothesis links overshoot to reduction in cochlear gain by the medial olivocochlear reflex. This is thought to reduce excitatory masking when the masker is at the signal frequency (within-channel effect) and suppressive masking when the masker is remote from the signal in frequency (across-channel effect). This hypothesis was examined in the first of the two experiments presented in this study. The results found no within-channel overshoot, indicating that the effect must be due to factors other than gain reduction at the signal frequency. While there was substantial across-frequency overshoot, the pattern of results was inconsistent with reduction in suppressive masking. Interpretation of results from overshoot experiments is often complicated by the possibility that the precursor itself might have a masking effect on the signal. The second experiment presented in this study was designed to overcome this problem.
Masking patterns of stimuli exhibiting enhanced detection for spectrally notched precursors.
Authors: Shen Yi , Richards Virginia M.
Published: July 2011

A narrow-band signal is subjective to less masking from a simultaneous notched masker if it is preceded by a precursor that occupies the same spectral region as the masker. The present study investigates the effect of the precursor on the internal representations of the signal and masker by measuring the masking pattern for short-duration probes as a function of the spectrotemporal placement. In the enhancement measurements, the signal was a 0.6-octave noise centered around 1 kHz, and the masker and precursor were broadband noises with spectral notches at the signal frequency. The amount of enhancement was measured as a function of the temporal separation between the precursor and masker. For corresponding conditions, the detection thresholds of a 6-ms tonal probe were measured at several temporal locations and at frequency regions occupied by either the signal or masker. These measured masking patterns were compared against the amount of enhancement, which showed that the presence of the precursor altered the internal representations of both the signal and masker. These masking patterns provide an opportunity to generate hypotheses on the plausible mechanisms underlying the auditory enhancement phenomenon.
Stop-like articulation of voiced dental fricative \δ\ in 2-year-old children: An acoustic analysis.
Authors: Zhao Sherry Y.
Published: July 2011

The voiced dental fricative \δ\ is frequently modified from its canonical form in American English, often becoming nasalized, lateralized, or stop-like in casual speech [Manuel (1995); Manuel and Wyrick (1999); Zhao (2010)]. Despite modifications in their production, \δ\ variants in adult speech were found to exhibit acoustic evidence suggesting a dental place of articulation, consistent with Stevens’ (2002) feature-cue-based model of speech processing. However, it is unclear whether children produce similar modifications for \δ\. This study compares the stop-like variant of \δ\ produced by 2 to 3-year-old children in the Imbrie Corpus [Imbrie (2005)] with adult productions. The data indicate that stop-like \δ\ frequently occurred in utterance-initial position, sometimes occurred when preceded by obstruent consonants, but rarely occurred when preceded by sonorant consonants or vowels in the children’s speech; these trends are similar to those found in adult data. Furthermore, stop-like \δ\ tokens had higher burst spectrum peak, lower normalized burst amplitude, and lower F2 at following vowel onset than \d\ tokens in the same vowel context; these acoustic differences are consistent with a dental place of articulation. The data suggest that children, like adults, may be preserving the dental articulation instead of substituting \d\ for \δ\, as is sometimes assumed.
Alveolar and velar stop releases during speech development.
Authors: McGowan Richard S. , Denny Margaret , Jackson Michel T-T. , Nittrouer Susan
Published: July 2011

It has been shown that children learning English tend to use tongue-to-palate contact patterns while producing velar and alveolar stop consonants that are not as well differentiated as for adults [Cheng et al., J. Speech, Language, Hearing Res. 50, 375–392 (2007)]. The electropalatographic experiments suggest that young children have not developed the fine motor control necessary for mature articulation of lingual consonants. It is possible that this may persist to become a speech disorder as they mature. We offer a complementary perspective that focuses on the mismatch between the acoustic and aerodynamic scaling from children’s vocal tracts to adult vocal tracts. In learning the motor control necessary to make a good distinction between alveolar and velar stops may be hindered by scaling mismatches. In this paper we will highlight acoustic measures of four children recorded every 6 months from the ages of 12–48 months playing with a care giver. We will consider both the formant frequencies at release and the shape of the burst spectrum to both help characterize the development acoustically and to infer what is causing the acoustics in the articulation. [Work supported by Grant No. NIDCD-RO1-001247.]
Machine learning approach to passive sonar localization.
Authors: Bissinger Brett E. , Culver R. Lee
Published: July 2011

A machine learning-based depth classifier for passive sonar is under development. The classifier is based on a support vector machine (SVM) paired with backward feature selection through margin-based feature elimination (MFE). The overcomplete feature space consists of features that have been shown to work in other passive sonar classifiers, features that have potential based on efforts in similar fields, and features based on consideration of the physics of the problem. Examples include central moments, autocorrelation coefficients, and modal amplitudes. The MFE algorithm can be used to reduce the dimensionality of the feature space, ranking the features according to their utility in the classification task. The classifier is applied to a horizontal array with a source at endfire. The most powerful features are obtained using an approach similar to matched-mode processing, except that the horizontal structure of the modes is utilized. [Work supported by Office of Naval Research Grant No. 321US.]
Bayesian tracking of multiple sources in an uncertain ocean environment.
Authors: Dosso Stan E. , Wilmut Michael J.
Published: July 2011

This paper describes a Bayesian approach to the problem of simultaneous tracking of multiple acoustic sources in a shallow-water environment in which water-column and seabed properties are not well known. The Bayesian formulation is based on treating the environmental parameters, noise statistics, and locations and complex strengths (amplitudes and phases) of multiple sources as unknown random variables constrained by acoustic data and prior information. Markov-chain Monte Carlo methods are applied to numerically sample the posterior probability density to integrate over unknown environmental parameters in a principal-component space. Closed-form maximum-likelihood expressions for source strengths and noise variance at each frequency allow these parameters to be sampled implicitly, substantially reducing the dimensionality of the inversion. The result is a set of time-ordered joint marginal probability distributions for the range and depth of each source, from which optimal track estimates and uncertainties are obtained.
Stochastic basis expansions applied to acoustic propagation in an uncertain, range, and depth-dependent, multi-layered waveguide.
Authors: Novick Jaison , Finette Steven
Published: July 2011

We study the utility of stochastic basis expansions in acoustic propagation through a multi-layered ocean waveguide in the presence of environmental uncertainty. Environmental uncertainty means that the parameters that describe the waveguide are treated probabilistically. Specifically, in the differential equation governing propagation, the uncertainty appears in the sound speed profile as an explicit dependence on a set of random variables. This implies that the acoustic field itself is a random field. Stochastic basis expansions are attractive because of their often exponential convergence. We use a complete set of multivariate orthogonal polynomials to compute the acoustic field’s statistics. The field propagates by a wide-angle parabolic equation through a rectangular waveguide comprised of three layers separated by two horizontal interfaces. A pressure release surface and hard bottom bound the waveguide. The water’s sound speed is a constant perturbed by a small, random range, and depth-dependent term that models a frontal zone, the middle sedimentary layer is stratified and modeled to represent uncertainty in sound speed measurements, and the bottom layer is a deterministic attenuating layer. We compare the field’s statistics generated by the stochastic basis to those generated by Monte Carlo simulations.
Vertical intensity structure in a shallow water waveguide.
Authors: Dall’Osto David R. , Dahl Peter H. , Choi Jee Woong
Published: July 2011

Acoustic intensity in an ocean waveguide is described by the local pressure and particle velocity, both of which can be described as a sum of modes. Analysis of the interaction between these modal components gives insight into the formation of characteristic intensity structures, such as interference patterns. Observations of the modal structure of the pressure and vertical velocity in a shallow water waveguide are presented using experimental data from an experiment off Korean coastal waters, the transverse acoustic variability experiment (TAVEX) that took place in August of 2008 17 km northeast of the Ieodo weather station, in waters 62 m deep. Mode filtering is performed on a 16 element vertical array that spans the water column (3 m spacing) for broadband (imploding light bulb) sources detonated at ranges from 200 to 1000 m at 40 m depth. The vertical velocity field, determined through the finite-difference approximation, and the pressure field at 230 Hz are represented by six propagating modes and their corresponding modal amplitudes. The interaction of these modal components is analyzed and PE simulated data are presented for comparison. Nondimensional indices are formulated relating the modal components of vector intensity and their utility as field indicators will be discussed. [Research supported by the U.S. Office of Naval Research and Agency for Defense Development, Korea.]
Observations of mode scattering from axial and off-axial sources in the North Eastern Pacific, Long Range Ocean Acoustic Propagation Experiment.
Authors: Chandrayadula Tarun K. , Colosi John A. , Worcester Peter F. , Dzieciuch Matthew A. , Mercer James A. , Howe Bruce M. , Andrew Rex K.
Published: July 2011

Experimental observations of the axial modes across range are crucial to verify and complement existing theories for internal-wave induced mode scattering. The 2004 Long Range Ocean Acoustic Propagation Experiment (LOAPEX) was conducted with the main objective of analyzing internal-wave induced mode fluctuations at ranges of 50–3200 km. During LOAPEX, a 75 Hz broadband source made transmissions at an off-axial depth of 350 m and an axial-depth of 800 m. The transmissions were received across a 40 element vertical array capable of resolving the first ten acoustic modes. The mode arrivals from the two source depths significantly differ from each other. For the axial source, the observed mode arrivals are strongly influenced by the low modes directly excited at the source or by nearest neighbor coupling. The shallow source in contrast excites the low modes at a much lower energy, and thus the axial arrivals from the shallow source transmissions are due to scattering from the high modes. This talk discusses the LOAPEX mode statistics for the two source depths. The observed mode statistics are compared with predictions from theory and simulations. [Work sponsored by a National Research Council Research Associateship Award at Naval Postgraduate School.]
Analysis of the vertical directionality of ambient noise: SPICE04 experiment measurements and model simulations.
Authors: Farrokhrooz Mehdi , Wage Kathleen E. , Dzieciuch Matthew A. , Worcester Peter F.
Published: July 2011

The SPICE04 experiment provided a unique opportunity to observe the ambient noise in the North Pacific [Worcester et al., J. Acoust. Soc. Am. 120(5), p. 3020]. Receptions on two 700-m segments of a deep vertical line array (DVLA) facilitate measurements of the vertical directionality of the noise above and below the surface conjugate depth. Several authors have proposed models for deep ocean noise, e.g., the spatial harmonic model developed by Cox [J. Acoust. Soc. Am. 54(5), pp. 1289–1301] and the normal mode model developed by Kuperman and Ingenito [J. Acoust. Soc. Am. 67(6), 1988–1996] and extended by Perkins et al. [J. Acoust. Soc. Am. 93(2), pp. 739–752]. The simulated data provided by these models can be used to assess the effects of array tilt on estimates of vertical directionality. In this talk, we first analyze the impact of tilt for the DVLA using the array element positions measured during the experiment. Then we compare the SPICE04 noise estimates for the two 700-m array segments and the relevant model output. [Work sponsored by ONR.]
Target detection in a shallow water environment using a two-dimensional array.
Authors: Gebbie John , Siderius Martin , Allen John S.
Published: July 2011

The detection and tracking of targets in cluttered, shallow water locations have become increasingly important for both maritime security and coastal environmental monitoring. Ambient noise contributions from snapping shrimp, as well as recreational and commercial ship traffic, can limit target detection performance. Few studies have investigated the possibility of enhanced passive acoustic detection in these locations using multiple arrays. Two synchronized 24 element arrays with 300 Hz–50 kHz bandwidth were deployed at the Kilo Nalu Nearshore Reef Observatory (University of Hawaii, Honolulu, HI) in an “L” shape configuration with a vertical array within the 12 m water column and horizontal array orthogonally aligned on the seafloor. This subtropical site is located between Honolulu Harbor and a recreational boating and diving area. Broadband snapping shrimp noise, which dominates the background levels, has a diurnal variation. A series of experiments examined the feasibility of passive acoustic monitoring with array beamforming of a variety of targets including small craft, open circuit scuba divers, and a REMUS autonomous underwater vehicle. The relative performance of narrowband versus broadband beamforming techniques for detection and tracking was quantified for these targets. Moreover, the applicability of nearfield techniques, such as wavefront curvature, was also investigated. [Work supported by the DHS.]
The diversity and uncertainty of the sonic experience in the classroom.
Authors: Shin Sangbong
Published: July 2011

It is critical to fully understand acoustical environments in classrooms because voice communication has been the dominant pedagogy for teachers in teaching students. Even though several standards have been applied to measure and understand the acoustical environment of core learning spaces, these are not adequate to examine multiple settings, identify the sources and receivers and their dynamic relationships, and to comprehend the nature of the specific acoustic events that occur in educational spaces since it is almost impossible to explain the diversity and uncertainty of the sonic experience in the classroom. In order to examine the variability in quantitative acoustical parameters in the spaces, an experiment was conducted with diverse configurations of measurement setups including different source types and diverse positions, different receiver types and diverse positions, diverse student conditions, and different measurement methods. To establish protocols for measurements in terms of soundscape of classrooms, analyzes were performed with impulse response signals in dynamic situations that yield specific results to reveal unique relationships between space, sound, and meaning. The results show that signal number average measurement used in the standards cannot measure the perception of sound for students as well as the physical characteristics of the soundscape in the classrooms.
Soundscape of a worship space.
Authors: Park Sang Bum
Published: July 2011

Worship spaces have a variety of sonic experiences, which they must accommodate such as the service of word and the service of music. Depending on the size and architectural properties of the church, speech or music may need to be electronically reinforced or amplified by sound system. Soundscape methods can be used to evaluate each of the multiple sources present in the room at multiple locations and receiver locations. Natural acoustic and reinforced sounds from the choir, organ, musical accompaniments, pastor or priest, key readers, and congregation were considered. Three churches were chosen for this study with regard to the level of reverberance and of the use of a sound system. Analysis of data required soundscape methods showed that while reverberation time was not very different at each receiver location, early decay time (EDT), center time (Tc), and speech transmission index (STI) obtained from the natural sound propagation in the rooms were different from the measurements made using the sound system because of the location, directivity, frequency response, and coverage of the loudspeakers. In conclusion, worship spaces have to be evaluated for both natural acoustic projection and reinforced or amplified projection of sounds using multiple source and receiver locations.
An experience reducing toilet flushing noise reaching adjacent offices.
Authors: Stewart Noral D.
Published: July 2011

An office building was experiencing loud toilet flushing noise in offices adjacent to the toilets. The toilets were a 1.2 gallon per flush model. A study by others documented some maximum A-weighted slow sound levels greater than 60 dB with most greater than 50 dB and recommended a limit of 40 dB. The building owner made changes including an improved wall on one of the seven affected floors and asked the author to repeat the measurements. Results were mostly in the range of 40 to 50. Sound levels within the rest rooms were greater than 80 dB, and within the toilet stall of the loudest toilet—96 dB. The sound peaked in the 2000 Hz octave. A wall on one floor was modified by adding a layer of damped gypsum with successful results. The remaining walls were then modified similarly. The resulting average level of four flushes was less than 40 dB in all offices though some individual flushes were slightly greater than 40 dB. It was evident that structural flanking was controlling the remaining sound reaching the offices.
Pump noise control in high rise condominiums.
Authors: Lilly Jerry G.
Published: July 2011

Noise generated by small pumps circulating water and refrigerants in multifamily residential buildings can be significant enough to generate complaints from residents if proper precautions are not taken. This presentation highlights several multifamily residential projects where pump and piping system noise was a significant source of noise complaints, and discusses what steps were taken to resolve the situation. General guidelines that can be used to prevent these problems in future projects will also be presented.
Steering acoustic intensity patterns generated by time-reversal, to move therapeutic particles in tissue.
Authors: Raghavan Raghu , Poston Tim , Lewis George K. , Gandhi Gaurav , Sarvazyan Armen
Published: July 2011

Convection-enhanced delivery (CED) is used in clinical trials to enhance the distribution of therapeutic molecules directly injected into tissue. Recent time-reversal acoustics (TRA) experiments [Lewis et al., J. Acous. Soc. Am. 128 2335 (2010)] show potential to improve CED with the use of delivery of acoustic forces within the tissue. TRA was used to focus ultrasound at the location of a transducer placed within rodent brain. Methods have been proposed to modify the TRA signals to steer the high intensity spots to new sites within a refractive inhomogeneous region such as the brain. We compare theory and measurement for the non-linear interpolation scheme proposed by Raghavan et al. [J. Acous. Soc. Am. 128 2336 (2010)], first in inhomogeneous gel phantoms. We assess the accuracy as well as stability of control for intensity and placement of “hot spots.” Time permitting, we shall present results for hot spot control in brain tissue and the resulting ability to improve distribution of small molecules delivered into brain tissue by CED. The ability to reliably steer high intensity spots in inhomogeneous media will allow applications beyond enhancing CED and beyond medicine.
A frequency compounding technique for improving the point spread function of superharmonic imaging systems.
Authors: van Dongen Koen W. A. , Danilouchkine Mikhail G. , Demi Libertario , van Neer Paul L. M. J. , de Jong Nico , Verweij Martin D.
Published: July 2011

Compared to fundamental imaging, harmonic imaging improves the axial and lateral resolution, while reducing the reflections from nearby artifacts and suppressing the effect of grating lobes. Superharmonic imaging combines reflections from the third, fourth, and fifth harmonic of the transmitted ultrasound pulse to improve the image quality of medical echography. A drawback of adding harmonic reflections is the possible degradation of the point spread function by ripple artifacts. The dual pulse technique reduces these ripples by transmitting two consecutive pulses with a slightly shifted frequency, and imaging the sum of both superharmonic reflections. Because two pulse-echo cycles are required, the frame rate is half that of a single pulse technique. In this presentation, a frequency compounding technique is described for a superharmonic imaging system with an interleaved phased array. With this technique, both frequency-shifted pulses are transmitted simultaneously by the odd and even transmit elements, respectively. Numerical results obtained with the iterative nonlinear contrast Source method are shown. Moreover, these are validated against experimental results. The results show that frequency compounding provides the benefits of the dual pulse technique while avoiding reduction of the frame rate. [Work supported by STW and NCF.]