bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual differences in the relation between perception and production and the mechanisms of phonetic imitation
Authors: Kim Donghyun , Clayards Meghan
Published: November 2016

This study uses phonetic imitation to understand more about how individuals perceive and produce speech and to explore the link between the two. We used manipulated stimuli with the goal of more directly probing the link and to test (1) whether individual listeners’ perceptual cue weights are related to their patterns of phonetic imitation and (2) the underlying mechanisms of phonetic imitation. Twenty-three native speakers of English completed a 2AFC identification task followed by a baseline production and a forced imitation task. Perception stimuli were created from productions of head and had recorded by a native speaker of English. Seven steps varying in formant frequency (created with TANDEM-STRAIGHT) were crossed with 7 duration steps (PSOLA in Praat). Imitation stimuli were a subset of stimuli from the perception task plus extended and shortened vowel durations. Our results suggest that phonetic imitation is mediated in part by a low-level cognitive process involving a direct link between perception and production as evidenced by imitation of all vowel durations. However, this study also suggests that imitation is mediated by a high-level linguistic component, i.e., phonological contrasts, which is a selective rather than an automatic process as indicated by imitation of phonologically relevant formant frequencies.
The acoustic counterpart to articulatory resistance and aggressiveness in locus equation metrics and vowel dispersion
Authors: Bang Hye-Young
Published: November 2016

Research on locus equation metrics (LEs) tend to take it for granted that vowel space is invariable across consonantal contexts. However, articulation-based studies report a mutual influence between neighboring segments such that segments with greater constraints in dorsal articulation are more resistant to and concurrently more aggressive in coarticulation than those with less constraints (Farnetani, 1990). We examine (1) whether articulatory resistance and aggressiveness can be acoustically captured through LEs and vowel dispersion and (2) how the relationship between LEs and the degree of coarticulation is mediated by vowel dispersion and delay in voicing. These questions are investigated in CV sequences in English –where C is one of /p t s ʃ/ that varies in the articulatory constraints imposed on the tongue dorsum. We manipulated the magnitude of coarticulation and voicing lag by contrastively stressing the target consonants. Our results show that there is a tight relationship between LE slopes and vowel dispersion where articulatory resistance and aggressiveness appear as the mirror image of each other in the acoustic signal. However, effects of hyperspeech simultaneously affect vowel dispersion, voicing delay, and LEs creating confounds. This calls for caution in the use of LE metrics as a measure of coarticulation.
Aperiodicity analysis of filled pause in the Corpus of Spontaneous Japanese database
Authors: Kawahara Hideki
Published: November 2016

We applied a novel aperiodicity analysis method (Kawahara et al. 2016, SSW9) to CSJ database (Maekawa, 2003, ISCA & IEEE Workshop). The applied method derives the amount of aperiodicity as a time-frequency map, using three staged procedures. The first stage derives a probability map of the fundamental component witout prior information. The second stage finds the most probable trajectory of the fundamental component based on a state transition model and calculates the initial estimate of FO. The final stage refines this initial estimat using FO adaptive time axis warping and instantaneous frequency of each harmonic component. Recursive application of this refinemet procedure provides simultaneous estimation of FO and aperiodicity map. Classification of filled pause using the refined FO trajectories and the aperiodicity maps will be discussed. [This work was supported by JSPS KAKENHI Grant Number JP26284062.]
Compressive sensing methods for passive localization and tracking of undersea acoustic sources
Authors: Forero Pedro A. , Baxley Paul
Published: November 2016

Matched-field processing techniques can achieve localization of undersea acoustic sources in both range and depth when sufficient environmental information is available. Unfortunately, these techniques are sensitive to environmental mismatch and often fail when localizing multiple acoustic sources. This work presents a family of acoustic source-localization techniques that similarly to matched-field processing exploit environmental information for localizing acoustic sources in both range and depth. Unique features of these methods are their explicit use of a sparse representation of the source-localization map and ability to model environmental mismatch. Tools from the areas of compressive sensing and mathematical optimization are leveraged for developing computationally tractable solvers that enable fast processing of high-dimensional source-localization maps. These localization techniques are also extended for tracking multiple acoustic sources. In this case, it is possible to exploit the inherent sparsity of the innovations that occur between consecutive source-localization maps to enhance the localization results at a negligible computational cost. Numerical results on experimental data are shown to illustrate the performance of the proposed methods.
Robust multi-frequency sparse Bayesian learning: Theory and simulations
Authors: Nannuru Santosh , Gemba Kay L. , Hodgkiss William S. , Gerstoft Peter
Published: November 2016

Compressive sensing based techniques have recently been applied successfully to underwater acoustics problems such as beamforming and matched field processing. Sparse Bayesian Learning (SBL) is one of the fast compressive sensing methods and is formulated using Bayesian statistics. In the SBL framework, source amplitudes are modeled as complex Gaussian random variables with unknown variance. Evidence maximization is performed to estimate the unknown source amplitude variance and source position. A major advantage of SBL over more commonly used methods such as basis pursuit is that it is computationally faster. In this work, we develop a robust sparse Bayesian learning algorithm that can account for model mismatch leading to errors in the replica vector dictionary. Specifically, the likelihood function is modified so that it takes into account the covariance matrix of error in replica vectors. We also extend the SBL algorithm to process observations from multiple frequencies. The derived update rule combines observations from all the frequencies in a holistic manner. We demonstrate the robust SBL algorithm with simulations. A comparison is done with other compressed sensing methods including basis pursuit and orthogonal matching pursuit.
A physical simulation of sound propagation from unmanned aerial vehicles
Authors: Zheng Z. C. , Zhang Junjian
Published: November 2016

The study is to investigate sound propagation from UAVs to the environment. The sound propagation is simulated based on the physical time and space, which is a time-domain simulation in a physical spatial domain. The investigation will be focused on the physics that is usually difficult to reveal using non-physical space simulation. The effects to be investigated include source characteristics and motion of UAV noise, influence of local environment such as atmospheric turbulence and wind shear,ground roughness and impedance, diffraction caused by local structures such as terrain, buildings, bushes, and trees. Because of proximity of UAVs to the ground, these effects are more significant for sound propagation from UAVs than from large aircraft that are at higher altitude from the ground. Examples of source recognition using the simulation results will also be discussed.
Novel algorithm for acoustic classification of unmanned aircraft systems
Authors: Brown Michael , Smith Cory , Hanford Amanda
Published: November 2016

Advances in Unmanned Aircraft System (UAS) technologies have made them smaller and more affordable, causing a proliferation in UAS activity. This increase has led to a rise in UAS-related incidents, exposing the need for stricter UAS regulation. Detection, Localization, and Classification (DLC) of UAS are important techniques for UAS regulation. However, DLC can be challenging, since UAS span a variety of shapes, sizes, speeds, propulsion systems, and operational altitudes; they can be hard to detect with radar; and they can operate in radio silence. Research supporting DLC of UAS has led to the development of novel, passive acoustic signal processing algorithms for real-time classification. In particular, data fusion algorithms combining kinetic and acoustic data into features for classification are being developed. Kinetic data are collected using acoustic signal source tracking algorithms, and spectral content is extracted from frequency-domain analysis. Using free-body modeling and Doppler compensation, classification probabilities can then be calculated for a list of known UAS. Initial classification algorithms have been developed and tested in MATLAB using UAS data collected in operational environments. The test results will also be presented.
Application of cross-correlation methods for passive acoustic unmannded aierial vehicle detection and tracking
Authors: Sedunov Alexander , Sutin Alexander , Salloum Hady
Published: November 2016

Stevens Institute of Technology has applied the cross-correlation method for the detection of low flying aircraft using passive acoustics. A modified cross correlation method was tested for finding the time difference of arrival of acoustic signals from various unmanned aerial vehicles (UAV), collected by NASA’s Langley Research Center. Cross-correlation was applied for UAV detection and for measurements of the time difference of arrival that is used for estimating the direction of arrival. The microphone separation combined with the high speed of the target had led to a significant differential Doppler effect leading to de-correlation of the received signals. For the compensation of those effects, Stevens applied a modified de-skewed short-time correlator (DSTC) approach. The detection ability of the cross-correlation method also depends on the cross correlation properties of ambient noise. The collection was performed in a relatively quiet area, to estimate the performance of the cross-correlation method in noisy areas the NASA UAV signatures were combined with ambient noise collected by Stevens. We demonstrate how the noise affects the detection distance. Special attention was paid to the influence of correlated components of the ambient noise. [The authors are grateful to Dr. Cabell (NASA’s Langley Research Center) for providing the acoustic data. This work was supported by DHS’s S&T Directorate.]
Acoustic detection of small unmanned aerial system using mills cross arrays
Authors: Kim Seongil
Published: November 2016

Two mills cross microphone arrays are used to detect and track a small unmanned aerial system (UAS). Each array consists of two 64-channel line arrays which are perpendicular each other. The cross-shape array is to detect targets approaching from any direction and the two-array system is a minimum number for localizing the target. The microphones of the line array are equally spaced as a design frequency of 2 kHz. The received acoustic signal is digitized as a sampling rate of 8 kHz and transferred to a remote signal processor by a radio link in real time. Beam-formed acoustic data are displayed in various ways to detect and localize the moving acoustic target. In this paper, the proto-type acoustic system for UAS detection as well as the experimental results will be discussed. Methods for array beam-forming, tracking and classifying the target and the acoustic characteristics of the target will be briefly mentioned.
Dynamic equilibrium model for stable nano- and micro-bubbles partly covered with hydrophobic material
Authors: Yasui Kyuichi , Tuziuti Toru , Kanematsu Wataru
Published: November 2016

In the dynamic equilibrium model, a bubble is only partly covered with hydrophobic material in contrast to the skin model that a bubble is completely covered with organic material. On the surface of the hydrophobic material in water, gas is highly concentrated due to the presence of depletion layer. Then, gas diffuses into a bubble near the peripheral edge of the hydrophobic material, which may balance with the gas diffusion out of a bubble from the other part of the uncovered bubble surface due to the higher internal gas pressure than the partial pressure of gas dissolved in the liquid water by the Laplace pressure. In the present study, not only the condition of the mass balance but also that of stability is numerically calculated. The results have indicated that a nanobubble could be stable when the fraction of the surface coverage by the hydrophobic material is more than 0.5 in water both supersaturated and under-saturated with gas (air). In slightly degassed water, a microbubble could be stabilized when the fraction of the surface coverage is on the order of 10-4 or less. These bubbles could play an important role in underwater acoustics as well as in acoustic cavitation.
Improved object detection sonar using nonlinear acoustical effects in bubbly media
Authors: Lee Kevin M. , Isakson Grace A. , Wilson Preston S.
Published: November 2016

Clutter from air bubbles can significantly impact the performance of object detection sonar in shallow water environments where bubbles are present due to breaking waves, wakes, or organic matter. Nonlinear acoustical effects can be excited in bubbly liquids at sound pressures below that required in bubble-free media and hence can be used to discriminate between bubbles and solid objects or to suppress bubble-related clutter altogether. Whereas such effects are widely exploited for ultrasonic biomedical imaging enhancement and it is hypothesized that dolphins exploit them in their biosonar, relatively less attention has been given to their use in naval, commercial, or oceanographic manmade sonar. Here, we describe laboratory tank experiments and modeling efforts aimed at exploiting these effects to improve object detection sonar. A bubble dynamics model was employed to investigate parameter space for nonlinear effects such as subharmonic and higher-order harmonic generation from regions of bubbly liquid and sonar-induced bubble translation. Laboratory experiments were conducted to verify the presence of these effects. Finally, a laboratory demonstration of a nonlinear bubble/object discriminating sonar, in which nonlinear effects are used to place markers on returns from regions of bubbly liquid, will be presented. [Work supported by ONR.]
Beam characteristics of the truncated parametric array generated by a panel piston radiator
Authors: Yang Desen , Li Hongdao , Shi Jie , Shi Shengguo , Zhang Haoyang , Li Di , Jin Shiyuan
Published: November 2016

A theoretical model is presented to describe the difference frequency beam characteristics of the truncated parametric array generated by a panel piston radiator. In this model, a low-pass acoustic filter is used to truncate the virtual-source. The truncated virtual-source can be viewed as a volume distributed cylindrical source and conic source within and beyond the Rayleigh distance, respectively. The difference frequency beam characteristics near the truncated position are significantly changed. Numerical simulation results show that the difference frequency beams near the truncated position are substantially sharpened with the distance between the observation point and the truncated position decreasing. Besides, the difference frequency beamwidth near the truncated position can be used to predict the farfield beamwidth of the truncated parametric array.
Research on the influence of dispersion in the shallow water waveguide on the parametric array
Authors: Yang Desen , Li Di , Shi Jie , Shi Shengguo , Zhang Haoyang , Li Hongdao
Published: November 2016

In practice, the application of parametric array is limited due to the effect of dispersion in the shallow water waveguide which has a significant impact on the propagation of the difference frequency wave. This paper attempts to provide better understanding of the difference frequency field in the shallow water waveguide by discussing the virtue source of parametric array in such circumstance. In the paper, the Green’s function of the shallow water waveguide is employed for calculating the difference frequency field with the help of virtue source in waveguide. It shows that the wavenumber mismatch caused by waveguide dispersion will restrain the accumulation of difference frequency wave and bring about fluctuations during the process of accumulation. Furthermore, this paper discusses the nonlinear interaction with different modes of pump wave based on the former conclusion and reveals pictures to describe the complicated mode structure of the difference frequency field.
Binaural simulation using six channel reproduction based on the finite difference time domain room acoustic analysis
Authors: Sakamoto Shinichi , Yokota Takatoshi , Yokoyama Sakae
Published: November 2016

For auralization of room acoustics, various simulation-reproduction systems, such as ray tracing, cone tracing, image source methods, and wave-based numerical analysis for sound field simulation, and transaural system, multi-channel loudspeaker system for sound field reproduction, have been developed. As a sound recording-reproduction system, the six channel system has been developed, in which a sound signal is recorded by orthogonally located six directional microphones having a cardioid characteristics and the recorded signals are reproduced by orthogonally arranged six loudspeakers. To obtain binaural signals for auralization with headphones, the six channel reproduction was combined with binaural recording using dummy head microphones. The proposed concept can be efficiently applied to room acoustic simulation. As a room acoustic calculation method, finite-difference time-domain method was employed in this study. The calculated room impulse responses were reproduced by six channel reproduction system, and the binaural signals are recorded using dummy head microphones. In this presentation, the concept of the reproduction system is first stated and some examples on room acoustic problems are introduced.
Sampling the sound field in auditoria using a large scale microphone array
Authors: Witew Ingo B. , Vorländer Michael
Published: November 2016

Acoustical measurements in auditoria can be laborious with microphones to be placed in large sampling areas that are divided by rows of seating and separated by balconies. As a result, practical studies are often based on measurements of a relatively small number of selected source-receiver combinations. The goal of this paper is to present a new measurement, visualization, and analysis approach for complex wave fields. The measurement apparatus, capable of automatically sampling the sound field in auditoria over a surface of 5.30 m x 8.00 m in high resolution, is described. Based on data collected with the microphone array, a case study of how sound is reflected and scattered from a concert hall’s boundaries is shown. The comparison of repeated measurements with and without the presence of chairs allows a new perspective on grazing sound propagation over theatre seating (“seat dip effect”). The presentation will conclude with the discussion of spatial fluctuations of acoustic properties as a factor of measurement analysis and uncertainty.
Determination of boundary conditions for room acoustics simulation by application of inverse calculation models
Authors: Aspöck Lukas , Maintz Thomas , Vorländer Michael
Published: November 2016

Simulation models for room acoustics simulation usually promise to deliver precise results for a certain frequency range. However, correct results can only be guaranteed if accurate input parameters are provided. Standardized methods for the determination of boundary conditions, the impedance tube and the reverberation chamber, include measurement uncertainties which might lead to different simulation results. These measurement methods also only capture valid results for special situations, e.g., normal or random wave incidence. This insufficient description of the boundary conditions makes it challenging to validate simulation models by comparing them to measured results. Even for rather simple room acoustic situations, state-of-the-art simulations fail to match measurements using in-situmeasurements or textbook values for the boundary conditions. In geometrical acoustics, these deviations can not only explained by insufficient measurement methods for the input data but also by different handling of reflection, scattering, and diffraction. To resolve the mismatch between measured and simulated results, optimization concepts have been proposed to determine input parameter sets for the simulation models. This work discusses two inverse approaches, evaluates their practicability for typical room acoustic scenarios, and presents the application in a comparison of room acoustic simulation software, the international round robin of auralization.
Bioacoustics research in Asia, promoted by Whitlow W. L. Au
Authors: Wang Ding , Wang Kexiong , LI SONGHAI , Akamatsu Tomonari
Published: November 2016

The sonar of dolphins (1993) written by Whitlow W. L. Au accelerated underwater bioacoustics research, especially in Asian odontocetes. Before this book, very limited ultrasonic recording of odontocetes and bioacoustics research of marine mammals have been done in Asia. The Yangtze freshwater cetaceans provided opportunities for Asian researchers to study biosonar behavior, passive acoustic monitoring methods, and auditory physiology of odontocetes. The above works were accomplished with the Whitlow Au's preceding studies as basic references. The passive acoustic monitoring method developed from the Yangtze finless porpoises has been applied internationally in recent years. With encouragement and supports from Whitlow Au, biosonar research, auditory sensitivity measurement, and long term acoustic monitoring have been extensively conducted on Chinese white dolphins and oceanic finless porpoises, which are the key species in coastal environmental assessment, especially for the windmill farm construction area in Asia. In the meantime, Whitlow dispatched students to help our researches and also accommodated Asian students in Hawaii. So far, there are more than five Ph.D. students from Asia in underwater bioacoustics field supervised or partially supervised by Whitlow Au. Some of them have already grown up as leading researchers in marine mammal bioacoustics in Asia.
Toward underwater channel impulse response estimation using sources of opportunity
Authors: Gemba Kay L. , Nannuru Santosh , Hodgkiss William , Gerstoft Peter
Published: November 2016

Passive acoustic tomography exploits the acoustic energy generated by sources with unknown spectral content such as sources of opportunity (e.g., cargo ships) to study the ocean. However, separating the channel impulse response (CIR) from a possibly moving, random radiator is non-trivial for coherent processing and the amount of unknown variables may leave the problem intractable. Using an incremental approach, we study the sparse CIR estimation problem for a single receiver. Second, we add multiple receivers, relax source spectrum knowledge, and study processor performance in resolving possibly coherent multipath arrivals across the vertical line array. Third, we discuss the extension to include multiple VLAs and sequential processing for a source with known location. Application of the Noise Correlation 2009 Experiment and the Santa Barbara Channel Experiment 2016 are discussed.
CANAPE-2015 (Canada Basin acoustic propagation experiment): A pilot tomography experiment in the Beaufort Sea
Authors: Dzieciuch Matthew , Worcester Peter F.
Published: November 2016

During the summer of 2015, test transmissions were made from a ship-suspended source to a moored vertical line array in the Beaufort Sea. These were carried out at a variety of ranges in order to prepare for a year-long (2016-2017) tomography experiment. A major concern was the expected transmission loss (TL) under the ice for current climatic conditions in the Arctic. A greater proportion of smooth first year ice (rather than rough multi-year ice) was expected due to climate change. This should lead to less scattering and a lower TL. Acoustic propagation in the Artic includes propagation in a weak shallow duct as well as arrivals of deeper turning rays. The TL of these different regimes is compared to that of an experiment in a tropical ocean, the Philippine Sea. The initial analysis shows that the Arctic TL scales with range to the fourth power. This large TL could be because the actual ice conditions in the experimental area had a high proportion of multi-year ice in 2015.
Acoustic noise interferometry and ocean dynamics
Authors: Godin Oleg A.
Published: November 2016

Noise interferometry relies on averaging long time series to reveal the deterministic features of the noise cross-correlation function, which contain information about the propagation medium. Unlike the solid earth, the ocean exhibits considerable variability at the time scales that are shorter than the necessary noise averaging times of hours and days. This variability is a primary factor that limits useful noise averaging times and underlies the more limited applicability of acoustic noise interferometry than of the better established seismic interferometry. This paper aims to quantify the restrictions, which are imposed on the noise interferometry by the ocean variability, and to identify possible applications of passive acoustic remote sensing to characterizing ocean dynamics. A theory will be presented that quantifies the coherence loss of measured noise cross-correlations due to gravity waves on the ocean surface, tidally induced changes in the water depth, and internal gravity waves. It is found that temporal variations of the ocean parameters lead to frequency-dependent suppression of deterministic features in the noise cross-correlation functions. The coherence loss limits the resolution of deterministic inversions. On the other hand, the passively measured coherence loss can be inverted to statistically characterize ocean dynamics at unresolved spatial and temporal scales.
Inferring salinity microstructure using high-frequency reciprocal acoustic transmission
Authors: Lavery Andone C.
Published: November 2016

The Connecticut River Estuary is highly stratified, strongly influenced by fresh water discharge and tides, and characterized by hydrographic features such as dynamic fronts, plumes, internal waves, shear instability, and the incoming salt-wedge. An experiment was conducted to measure the impact of these hydrographic features on the propagation of high-frequency sound, and to use the path-averaged acoustic fields to infer properties of salinity microstructure. Two 120 kHz, 4-element arrays, each element with reciprocal transmission capabilities, were deployed for 5 days mid-water-column, spanning multiple tidal cycles and a range of discharge conditions. Extensive environmental data were collected, including ADCP profiles, CTD profiles, salinity microstructure at various depths, and broadband acoustic backscatter (100-600 kHz). Results from this experiment show that 1) shear instabilities dominated the structure of the sound propagation during the ebb tide and were coherent features across the propagation path length, 2) salinity stratification could be deduced from reciprocal transmissions, 3) the slope of the shear instabilities could be inferred by combining the ADCP data and arrival times at different depths, and 4) and the incoming salt-wedge was the dominant hydrographic feature affecting the sound propagation during the flood tide. [This work was funded by the ONR Ocean Acoustics Program.]
Information content of ocean travel-times in the Philippine Sea
Authors: Powell Brian , Williamson Sarah , Zhao Xiaofeng
Published: November 2016

The Philippine Sea is a highly energetic region of varying scales from planetary down to tidal. Significant eddy activity is present throughout the region with enhanced mesoscale activity centered around 22N. Tidally driven internal waves emit from the Luzon Strait into the Philippine Sea and are the most energetic in the world. These multiple dynamical scales combine to have significant influence on the density structure and sound speed in the region. In 2010, a large deep-water acoustic transmission experiment was conducted to investigate the acoustics in such a dynamic environment. A total of seven transceivers were used for providing significant coverage over the western Philippine Sea. In this talk, we use a data-assimilative numerical ocean model to investigate how travel-times from the acoustic array covary with the ocean. Using both predictions and analyses from the model, we investigate how well the model is capable of resolving acoustic rays and travel-times without the constraint of the acoustic observations. We then work to quantify how the ocean covaries with acoustic travel-times to help us to understand the variability in the ocean that controls the propagation and what the propagation can tell us about the oceanic variability.
Deblurring acoustic signals for statistical characterization in applications of ocean acoustic tomography
Authors: Taroudaki Viktoria , Smaragdakis Costas , Taroudakis Michael
Published: November 2016

The signal characterization method suggested by Taroudakis et al. (J.Acoust. Soc. Am. 119, 1396-1405 (2006)) based on the statistics of its 1-D wavelet transform coefficients and successfully applied for inverting acoustic signals in applications of acoustical oceanography has been proven to be sensitive to noise contamination of the signal, but still, it provides good inversion results if an appropriate denoising strategy is applied. In this work, the statistical signal characterization is applied to signals which are both blurred and noise contaminated. Deblurring of the signal is achieved by means of a technique introduced by Taroudaki and O’ Leary (SIAM J. Sci. Comput. 37(6), A2947-A2968 (2015)) for image deblurring, and it is based on a statistical near optimal spectral filtering technique that takes advantage of the singular values of the approximated blurring matrix and the Picard Parameter of the signal that allows for estimation of the additive noise properties and estimation of the error. The study is extended to cases when no accurate knowledge of the blurring mechanism is available. It is shown by typical simulated experimental data that the combination of deblurring and simple denoising strategies provide good results with respect to both signal characterization and subsequent inversions.
Emerging quantitative ultrasound applications: From diagnosing disease to monitoring of therapy
Authors: Oelze Michael L.
Published: November 2016

Ultrasound has traditionally been considered an imaging modality characterized by high spatial resolution but low contrast. Conventional ultrasonic imaging may be sensitive to the detection of anomalous tissue features, but the ability to classify these tissue features often lacks specificity. However, recent advances in quantitative ultrasound (QUS) have emerged which can improve diagnostics by providing new sources of image contrast and specific numbers tied to tissue state. QUS imaging can encompass a wide variety of techniques including spectral-based parameterization, elastography, flow estimation, and envelope statistics. Spectral-based techniques include the estimation of the backscatter coefficient, estimation of attenuation, and estimation of scatterer properties such as the correlation length associated with an effective scatterer size and the acoustic concentration of scatterers. Envelope statistics include the estimation of the number density of scatterers and quantification of coherent to incoherent signals produced from the tissue. In this talk, successful applications of QUS will be discussed demonstrating the ability of spectral-based QUS and envelope statistics approaches to improve medical diagnostics including cancer detection and classification of solid tumors in the breast or thyroids, grading of fatty liver disease and monitoring and assessment of therapy in solid tumors.
Selected quantitative ultrasound successes
Authors: Han Aiguo , O'Brien W. D.
Published: November 2016

The objective of soft tissue quantitative ultrasound (QUS) is to improve diagnostic ultrasound imaging via quantitative outcomes. Over the past three or so decades, there have been an increasing number of QUS successes. Four QUS successes will be highlighted, from theoretical development to clinical applications. Significant ultrasonic scattering mechanistic details have resulted from the spatial correlation among the scatterers (modeled by the structure function) as well as from the individual scatterers (modeled by the form factor), for which there have been successes with both theory and applications. In collaboration with colleagues at the University of California, San Diego, nonalcoholic fatty liver disease (NAFLD) is being assessed from model-free QUS parameters from which both the backscatter coefficient and the attenuation coefficient show dependencies with the liver fat content in human subjects. Likewise, in collaboration with colleagues at the University of Illinois at Chicago, spontaneous preterm birth is being assessed as early as 20 weeks of gestation in pregnant women from the model-free QUS parameter attenuation coefficient. [NIH Grants NIH R01DK106419 and R37EB002641.]
Quantitative ultrasound for tumour characterization and a priorichemotherapy response prediction
Authors: Czarnota Gregory
Published: November 2016

Previous studies have demonstrated that quantitative ultrasound (QUS) is an effective tool for monitoring breast cancer patients undergoing neoadjuvant chemotherapy. Here, for the first time, we demonstrate the clinical utility of pre-treatment QUS texture features in predicting the response of breast cancer patients to NAC. Using a 6 MHz center frequency clinical ultrasound imaging system, radiofrequency breast ultrasound data were acquired from 92 locally advanced breast cancer patients prior to their NAC treatment. QUS spectral parameters including mid-band fit, spectral slope, and spectral intercept, and average acoustic concentration and average scatterer diameter were computed from regions of interest in the tumor core and its margin. Subsequently, gray-level co-occurrence matrix textural features were extracted from the parametric images as potential predictive indicators. Results were compared with the clinico-pathological response of each patient determined at their treatment end. A composite QUS feature demonstrated a favourable response prediction with sensitivity, specificity, and AUC of 86%, 83%, and 0.77, respectively, using a Naïve Bayes classifier. The findings here suggest that QUS features of breast tumors are strongly linked to tumor responsiveness. The ability to identify patients that would not benefit from NAC would facilitate clinical management that has minimum patient toxicity and maximum outcome.
Quantitative ultrasound of the uterine cervix
Authors: Hall Timothy J. , Feltovich Helen , Rosado-Mendez Ivan M. , Drehfal Lindsey C. , Guerrero Quinton W. , Palmeri Mark L.
Published: November 2016

We are developing methods to objectively describe the acoustic and viscoelastic properties of the in vivo cervix to monitor the structural changes that occur during pregnancy. Clinicians commonly use digital palpation to subjectively judge cervical softness knowing the cervix softens prior to parturition. Premature softening of the cervix is a risk factor for preterm birth which has enormous morbidity and financial consequences. However, this is a challenging tissue for quantitative ultrasound (QUS) investigations because its microstructure is layered and pseudo-aligned within each layer. Also, data are typically acquired with a transducer that is in contact with the outer layer of the cervix, so QUS analysis is necessarily done very close to the transducer surface. To avoid violating assumptions used in QUS algorithm development, we use a prototype transducer that allows us to perform QUS parameter estimation as close as 3mm from the transducer surface. Further, we systematically test for various forms of echo signal coherence instead of assuming the backscatter is from diffuse scattering. Preliminary results in humans and non-human primates suggest the cervix significantly softens in early pregnancy, but the underlying collagen microstructure remains intact until very near delivery. Methods for this analysis and results will be briefly described.
The development of wavenumber extended multi-dimensional interpolation techniques for aeroacoustic problems
Authors: Jang Seokjong
Published: November 2016

One of the main concerns of computational aeroacoustics is how to solve aeroacoustic problems with complex geometry. The dissipation/dispersion errors should be minimized to obtain accurate acoustic solutions because numerical solutions for aeroacoustic problems are over-susceptible. The wavenumber extended multi-dimensional interpolation techniques were developed in order to satisfy those requirements. The size of a stencil used for standard multi-dimensional interpolation can be determined. Adding the number of stencils with optimized interpolation coefficients enables obtaining the distribution function optimizing the relationship between dispersion and dissipation. Through the optimization process in frequency domains, this technique minimizes the dispersion/dissipation errors generated by the data transfer between multi-grid systems. In addition, a proper limiting process was proposed to remove a numerical instability and oscillations in a discontinuous region. Several problems were numerically simulated by applying the wavenumber extended multi-dimensional interpolation. The results of a advanced technique was validated by being compared with the existing conventional interpolation techniques.
Study on coupled analysis for compact acoustic systems using finite-difference time-domain method based on Kirchhoff-Love plate theory and elastic wave
Authors: Takimoto Hayato , Kajikawa Yoshinobu , Toyoda Masahiro , Miyakura Takashi
Published: November 2016

In this paper, we propose a coupled analysis method for compact acoustic systems (e.g., micro speakers, electret condenser microphones) using finite-difference time-domain (FDTD) method based on the Kirchhoff-Love plate theory and elastic wave. Acoustic systems are usually analyzed through any numerical analysis technique based on wave propagation. However, an exact frequency response is rarely obtained for compact acoustic systems. This is because the standard FDTD method cannot treat the change of the frequency response due to the air viscosity and cannot also treat the wave propagation in a solid. Thus, we cannot obtain exact frequency responses for compact acoustic systems through the analysis of coupled fluid-solid model based on standard FDTD method. In order to solve these problems, we utilize a coupled analysis method based on Kirchhoff-Love plate theory and elastic wave FDTD method considering air viscosity. The analysis method models diaphragm and voice coil as a two-dimensional plate model based on Kirchhoff-Love plate theory and air as a three-dimensional model based on elastic wave FDTD method considering the air viscosity. In this paper, we demonstrate the effectiveness of the analysis method through some comparisons between calculated and measured frequency responses.
Eastern and Western free reed instruments: Acoustics, history, and culture
Authors: Cottingham James P.
Published: November 2016

There are two families of free reed instruments. Mouth-blown instruments employing free reeds coupled to pipe resonators have been used throughout East and Southeast Asia since ancient times. The sheng, sho, khaen, and bawu are typical examples. Details of the origin and development of these instruments are not known, but are closely connected with the history and prehistory of a multitude of ethnic groups. The instruments of the Western free reed family are of modern origin, originating in Europe around 200 years ago. These include the reed organ, harmonium, harmonica, and the accordion-concertina family. This paper explores significant differences in the acoustical design of the two groups of instruments and surveys historical developments of each, including examples of possible connections and influences between the two families. Interesting developments involving the two families of free reed instruments occurred as elements of their original musical cultures became mixed in the nineteenth and twentieth centuries.
Transforming rhythmscapes
Authors: Krishnamurthy Rohan
Published: November 2016

Originating in India over two millennia, the mridangam is one of the most ancient, complex, and versatile hand drums in the world. The pitched nature of the two-sided drum and a complex split finger technique enable the creation of over a dozen unique tones. The acoustics of the mridangam, especially the tonal drumhead, will be discussed. Musical excerpts will demonstrate how the timbres and sound structures of the mridangam have intertwined with diverse musical genres from around the world, including global percussion ensembles, symphony orchestras, jazz ensembles, and Hollywood scores. The recent phenomenon of real-time online music education will also be discussed as a seminal mode of disseminating the mridangam tradition across the globe. The presentation will conclude with a live, interactive performance.
Differences between audio engineers and players in the subjective evaluation on the recording position of the Koto (Japanese harp)
Authors: Saito Shun , Kamekawa Toru , Marui Atsushi
Published: November 2016

The objective of this study was to examine the appropriate recording position for the Koto (Japanese harp). The sound of the Koto used as experiment stimuli was recorded at 54 different spherical microphone positions. A group of audio engineers and a group of Koto players rated the recorded stimuli on thirteen attribute rating scales. The result of evaluation was performed in an analysis of variance using two factors, namely, the recording position and the evaluator group. In the results, significant differences between the two groups were not found in almost all attributes. However, it should be noted that in the assessment of a few number of attributes, significant differences were observed in interaction among the recording positions and between the groups. For determining suitable factors within the attributes, a factor analysis was performed. The factor scores from the results of the factor analysis showed that the tendencies of each group in regards to the recording positions were different, and results showed that some recording positions had higher scores. It was found that factor one of each group tended to have a higher score in the upward recording position on the players side.
Angle dependent effects for impulse noise reduction for hearing protectors
Authors: Murphy William J. , Adams Daniel , Graydon Pamela S.
Published: November 2016

The exposure at the ear in response to a forward-propagating wave depends upon the angle of incidence at the head, the nominal sound pressure level of the impulse and the attenuation of hearing protection (if worn). The unoccluded and occluded responses of an acoustic test fixture equipped with two G.R.A.S. IEC 60711 couplers ¼ inch microphones were measured in 15 degree increments for impulses with nominal peak sound pressure levels of 150 and 160 decibels. The attenuation was assessed in a variety of ways: Impulse Peak Insertion Loss (IPIL), change in A-weighted Equivalent Energy, and change in the Auditory Hazard Unit. Generally, the LAeq was quite similar to the (IPIL). However, the change in AHUs predicted less attenuation than was actually observed. The lower performance for AHUs may be attributable to the nonlinear hazard growth for the unoccluded ear. These results will be compared with continuous noise assessments of the effect of angle on protection.
Controlling sample and particle behaviour in microfluidic systems using acoustic forces
Authors: Neild Adrian , Alan Tuncay , Sesen Muhsincan , Collins David , Brenker Jason
Published: November 2016

Acoustic forces have been widely used to control microparticles within microfluidic systems. Such acoustofluidic systems have been very successful in tasks such as cell sorting, however, to date efforts have been mostly limited to single phase systems. Just as the contrast in acoustic impedance between a fluid and suspended particle means that acoustic forces can be exerted on the particle, a contrast also exists at the interface between two immiscible fluids. This work explores ways in which such acoustically generated forces can be used in digital (two phase) microfluidic systems. Digital microfluidic systems have gathered significant interest because of the potential of single cell analysis and on-chip chemical reactions. In the paradigm of a lab-on-a-chip, each droplet is analogous to a test tube; however, due to the rapidity of producing large numbers of droplets, reaction based systems can run into difficulties as each test tube contains the same sample. In order to gain control over droplet behavior, acoustically actuated systems have been developed to produce individual droplets, selectively merge droplets, and to steer them at a junction, enabling control of the type of chemical in each droplet in a sequence, chemical reaction initiation and guidance of droplets around a chip.
Negative radiation torque using “acoustical sheets”
Authors: Mitri Farid G.
Published: November 2016

An interesting effect of negative acoustical radiation torque generation and direction reversal of the spinning of an absorptive cylinder is reported [F.G. Mitri, Wave Motion 66, 31-44 (2016)]. The emergence of the acoustic spin radiation torque experienced by the circular cylinder in a nonviscous host fluid is a consequence of acoustic attenuation inside its absorptive material. Depending on the direction of the shift from the center of a focused Hermite-Gaussian “acoustical-sheet” beam of first-order, the spin torque is negative or positive, causing the rotation of the cylinder in the polar plane in either the clockwise or the anticlockwise direction, respectively. Notice that at the center of the beam, the torque vanishes as required by symmetry. In the off-axial configuration, the spin torque sign reversal is dependent on the variation of absorption of both the longitudinal and shear waves inside the viscoelastic material. The effect of changing the non-dimensional size parameter ka (where k is the wavenumber and a is the cylinder radius) has a substantial effect on the negative spin torque generation. Potential applications are in acousto-fluidics, particle manipulation, and handling and imaging microscopy to name a few.