bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine listening in combination with microphone arrays for noise source localization and identification
Authors: Müller-Trapet Markus , Cheer Jordan , Fazi Filippo M. , Darbyshire Julie , Young J. Duncan
Published: June 2017

In a recent project, a large microphone array system has been created to localize and quantify noise sources in an Intensive Care Unit (ICU). In the current state, the output of the system is the location and level of the most dominant noise sources, which is also presented in real-time to the nursing staff. However, both staff as well as patients have expressed the need for information about the types of noise sources. This additional source identification can also help to find means of reducing the overall noise level in the ICU. To accomplish the source identification, the approach of machine listening with a deep neural network is chosen. A feed-forward pattern recognition network is considered in this work. However, it is not clear which types of features are best suited for the given application. This contribution thus examines the problem from a practical point of view, comparing different features including those related to sound perception, such as specific loudness, Mel-frequency cepstral coefficients, as well as the output of a gamma-tone filter bank. Additionally, the concept of time-delay networks is tested to see whether a better classification of the signals can be achieved by including their time history.
Speech intelligibility under realistic classroom acoustics
Authors: Puglisi Giuseppina E. , Warzybok Anna , Kollmeier Birger , Astolfi Arianna
Published: June 2017

Speech recognition is fundamental in everyday communication environments, especially in school classrooms where the teaching-learning process takes place. Extensive literature is available that refers to speech intelligibility studies on the effect of artificially added reverberation and speech-shaped noise, whereas there is a little number of works that account for realistic acoustics. This work investigates the effect of measured classroom acoustics on speech intelligibility, accounting for the effect of informational and energetic masking, distance teacher-to-listener between and binaural unmasking. Speech reception threshold (SRT) corresponding to signal-to-noise ratio yielding 80% of speech intelligibility was measured in two acoustically different primary school classrooms. The acquired binaural room impulse responses were convolved with anechoic speech and noise stimuli, then presented via headphone to a group of adult normal-hearing listeners. The results show that SRTs were lower (better) under optimal classroom acoustics, i.e., with reverberation time of 0.4 s. Also, SRTs under informational masking noise were averagely higher (worse) by 6.6 dB than SRTs under energetic masking, proving that the former masker is more competing than the latter and needs to be deepen in future research. The binaural unmasking was observed only for a short teacher-to-listener distance in the room with a shorter reverberation time.
Potential audibility and side effects of ultrasonic surveillance monitoring of PA and Life Safety Sound Systems
Authors: Mapp Peter
Published: June 2017

Ultrasonic surveillance monitoring, to check the operational integrity of PA and Emergency Communication Systems, has been in existence for well over 30 years—particularly in Europe. Since its inception, there has been debate as to the potential audibility that these systems may have. As the vast majority of PA systems engineers and designers have not heard or experienced any effects, is has generally been assumed that the general public do not either. Recently however, concern has been raised and claims of ill effects have been reported. There is however, little or no data as to the ultrasonic sound levels that PA systems actually emit. The paper discusses the results of an initial survey of ultrasound radiated by PA systems and compares the results with a number of international standards—there currently being little or no specific guidance. The paper reviews the technology involved, typical emission levels and concludes by making a number of recommendations to assist with the control of ultrasonic emissions from PA systems that should help to mitigate unintended side effects.
Relations between acoustic quality and student achievement in K-12 classrooms
Authors: Wang Lily M. , Brill Laura C. , Lester Houston , Bovaird James
Published: June 2017

Prior work by Ronsse and Wang (2013) found that, in elementary schools, higher unoccupied background noise levels do correlate to lower student achievement scores in reading comprehension, but that study did not include detailed logs of acoustic conditions taken during the school day nor did it investigate middle or high school classrooms. More recently, measurements of the indoor environmental conditions in 110 K-12 classrooms, logged over a period of two weekdays three times seasonally, were taken over the 2015-16 academic year. Assorted acoustic metrics have been calculated from the raw measurements and a confirmatory factor analysis has been conducted to statistically create a comprehensive construct of “acoustic quality” that includes three general components: room characteristics (including reverberation times), occupied noise levels, and unoccupied noise levels. Standardized test scores of students who learned in the measured classrooms that year have also been gathered as an indicator of student achievement. Results from a structural equation model are presented to show how the various components of the proposed acoustic quality construct relate to student achievement. [Work supported by the United States Environmental Protection Agency Grant Number R835633.]
Study of the impact of aircraft noise on annoyance and cognitive task performance regarding the distance from the airport
Authors: Verneil Anne-Laure , Lavandier Catherine , Suomalainen Emilia
Published: June 2017

Aviation traffic is expected to increase by 30% by 2025. Aircraft noise annoyance of people living near airports is one of the parameters which could limit this industry. Indeed, occurrence of flights takes part in noise annoyance. In addition to non-acoustic factors, acoustic parameters such as noise level or temporal and spectral aspects are involved in annoyance. In this study, two assumptions are studied: (1) close to the airport, the emergence of the flyovers constitutes the most important parameter, (2) far from the airport, this is the flyover duration. This paper presents a perceptive experiment which aims at verifying these assumptions, questioning about short term annoyance in laboratory. Three sequences of aircraft noise have been recorded at three different distances from the airport. Short term annoyance after each sound sequence has been assessed by about 50 participants. During the experiment, cognitive tasks were performed: (1) the reading of a text presented on a computer screen equipped with an eye tracker in order to measure the velocity of reading and the number of retro-saccades, (2) a memorization task where the performance is assessed with the number of errors and the reaction time. The acoustic characteristics, perceived annoyance and performance measurements are then crossed. The results are presented and discussed in this paper.
Low-order modeling of fan broadband interaction noise
Authors: Villafranco Dorien O. , Grace Sheryl
Published: June 2017

For commercial aircraft equipped with a modern high-bypass turbofan engine, a primary noise source on take-off and at approach has been attributed to the fan stage of the engine. The largest contribution to fan noise is rotor wake impingement on the fan exit guide vanes (FEGVs). The interaction creates both tonal and broadband noise. Engine designers have reliable tools for the prediction of tonal noise while prediction methods for broadband noise are still being developed. In the current work, a low-order method for simulating the broadband noise downstream of the fan stage of the engine is presented. Comparisons between computational results and experimental data are shown. The method produces good predictions of the spectral shape when compared to the experimental measurements. The basic low-order method models the FEGVs as flat plates. While reasonable predictions are attained with this simplification, increased fidelity is sought through inclusion of the real vane geometry in the low order model.
Enhancing the convergence of fast multipole expansion at intermediate frequency
Authors: Zhou Hui
Published: June 2017

In this work, we examined acoustic wave scattering from media having a spacial variation in its compressibility contrast. Typically, the pressure in the scattered field can be expressed as a Neumann series when the compressibility contrast is relatively small. However, divergence can occur due to resonant scattering. It has been shown that Padé Approximants method can be used to extend the range of validity of the solution. Fast multipole expansion method is applied to evaluate the terms of Neumann series. Particular interest is paid to the numerical convergence of the translation operator used in the fast multipole method.
Utilizing a discontinuous Galerkin method for solving Galbrun’s equation in the frame of aeroacoustics
Authors: Guettler Marcus , Marburg Steffen
Published: June 2017

In the research field of aeroacoustics, scientists and engineers developed broad varieties of mathematical formulations to investigate numerically flow-induced noise in an early stage of product design and development. Besides the already established theories such as the linearized Euler equations (LEE), the linearized Navier-Stokes equations (LNSE) and the acoustic perturbation equations (APE) which are all written in a pure Eulerian frame, Galbrun utilized a mixed Eulerian-Lagrangian frame to reduce the number of unknowns. Despite the advantages of fewer degrees of freedom and the reduced effort to solve the system equations, using the usual finite element method suffers from instabilities called spurious modes that pollute the solution leaving useless results. In this work, the authors apply a discontinuous Galerkin method to overcome the difficulties related to spurious modes when solving Galbrun’s equation in a mixed and pure displacement based formulation. The results achieved with the novel approach are compared with results from former attempts to solve Galbrun’s equation.
Blind modeling of binaural unmasking of speech in stationary maskers
Authors: Hauth Christopher F. , Ewert Stephan D. , Brand Thomas
Published: June 2017

The equalization cancellation (EC) model predicts the binaural masking level difference by equalizing interaural differences in level and time and increasing the signal-to-noise ratio (SNR) using destructive and constructive interferences. The EC model has been successfully combined with the speech intelligibility index (SII) to predict binaural speech intelligibility. Here a blind EC model is introduced that relies solely on the mixture of speech and noise, replacing the unrealistic requirement of the separated clean speech and noise signals in previous versions. The model uses two parallel EC paths, which either maximize or minimize the EC output level in each frequency band. If SNR is negative, minimization improves the SNR by removing the interferer component from the mixed signal. If SNR is positive, maximization improves the SNR by enhancing the target component. Either the minimizing or maximizing path in each frequency band is selected blindly based on envelope frequency-selective amplitude modulation (AM) analysis. The model is evaluated for speech in stationary speech shaped noise in different spatial configurations. The suggested AM-steered selection in the EC stage demonstrates that a simple signal driven process can be used to explain binaural unmasking of speech in humans, disregarding localization and higher-level processes.
An account for the spatial advantage in multitalker situations based on glimpses
Authors: Schoenmaker Esther , van de Par Steven
Published: June 2017

Spectro-temporal regions with a high local signal-to-noise ratio (SNR), so-called glimpses, play a vital role in the intelligibility of target speech against fluctuating interferers (e.g., concurrent speech signals). These glimpses provide access to reliable information on local signal properties. In a situation with spatially separated speech sources, a spatial advantage relative to a situation with collocated sources can be observed. This advantage is generally conceived to be composed of a monaural contribution due to better-ear listening, and a binaural contribution due to either binaural unmasking or segregation supported by spatial cues. A previous study [Schoenmaker and van de Par (2016), Adv. Exp. Med. Biol. 894, 73-81] provided evidence against the use of binaural unmasking and in favor of spatial segregation based on spatial cues extracted from glimpses. New data suggest that the better-ear contribution relies on the amount of target speech in glimpses, rather than the global SNR of the masked target speech. Together this suggests that all cues used for speech intelligibility in spatial multitalker situations are obtained from well-audible glimpses. Specifically, better-ear listening provides monaural cues to the target speech, while binaural listening provides spatial cues that improve allocation of extracted information to the correct talkers.
Age-related cortical changes in spatial auditory attention
Authors: Ozmeral Erol J. , Berg Madeleine , Eddins David A. , Eddins Ann C.
Published: June 2017

Along with established effects of age on hearing sensitivity, there is a growing body of evidence that the aging auditory system suffers from reduced temporal resolution as well. This, in combination with changes in attentional-resource allocation, could have profound effects on the ability for older listeners to selectively attend to spatial locations—a key component to successful listening and communication in challenging auditory environments. Because behavioral tasks rarely have an unattended comparison and electrophysiological tasks rarely have an attended comparison, it is difficult to ascertain the extent to which selective attention mediates or sharpens spatial tuning. To address this shortcoming, we measured cortical responses using electroencephalography for moving stimuli in the free field during both passive and active conditions. Active conditions required listeners to respond to the onset of a stimulus when it occurred at a specific location (either 30° to the left or right of center). Both younger and older normal-hearing listeners participated in the study. The event-related potentials as well as the source-localized activity in regions of interest associated with sensory processing (i.e., left and right auditory cortices) and top-down control (i.e., dorsal fronto-parietal areas) revealed considerable morphological differences between the age groups.
Investigation of the flow- and sound-field of a low-pressure axial fan benchmark case using experimental and numerical methods
Authors: Zenger Florian , Junger Clemens , Kaltenbacher Manfred , Becker Stefan
Published: June 2017

An extension of a benchmark case for a low-pressure axial fan is presented. The generic fan is a typical fan to be used in commercial applications. The fan design procedure, as well as the experimental setups are described in detail. The numerical approach is based on a forward coupling between a flow simulation with ANSYS Fluent and an aeroacoustic source term and wave propagation computation with multiphysics research software CFS + +. Experimental and numerical data for aerodynamics and aeroacoustics are compared. This includes aerodynamic performance (volume flow rate, pressure rise and efficiency), fluid mechanical quantities on the fan suction and pressure side (velocity distribution and turbulent kinetic energy), wall pressure fluctuations in the gap region and acoustic spectra at various microphone positions. Finally, a comprehensive data base of an axial fan was generated. Flow field properties at the fan suction and pressure side from the CFD simulation are in good agreement and spectra from the wall pressure fluctuations are in excellent agreement with the experimental data. Spectra from the computed acoustic pressure tend to slightly overestimate the experimental results. Based on the good agreement of both aerodynamic and aeroacoustic data, a thorough study on the dominant sound generation mechanisms is made.
Atmospheric acoustic modes between a complex ground impedance and an artificial absorber
Authors: Evans Richard B. , Di Xiao , Gilbert Kenneth E.
Published: June 2017

Atmospheric acoustic normal mode computer codes are faced with finding the complex modal eigenvalues. Searching in the complex plane is difficult and requires special numerical techniques and custom software. A Legendre-Galerkin technique that reduces the problem to a complex matrix eigenvalue problem can be solved by commercially available software. This proposed Legendre-Galerkin method is described as the projection of the acoustic normal mode problem onto a recombined basis of Legendre polynomials. The modal approach is best suited for providing benchmark quality results in cases when guided modes dominate the problem. Such results are useful in establishing the validity and interpreting the characteristics of atmospheric acoustic fields computed with the parabolic equation method, for the same problem. The Legendre-Galerkin method is applied to cases with a ground based duct and an elevated duct. Measured wind speeds, from a costal experiment, provide the effective downwind and upwind sound speed profiles with these ducted characteristics.
Dynamical analysis of stroke induced vibrations in tennis racket
Authors: Chadefaux Delphine , Rao Guillaume , LE CARROU Jean-Loïc , Berton Eric , Vigouroux Laurent
Published: June 2017

Tennis rackets are mostly designed disregarding the boundary condition managed by the player's hand on the handle. This process leads to a lack of accuracy in the mechanical parameters the manufacturers provide to their rackets in order for them to be reliable and comfortable to the player. Our work aimed at providing a better understanding of the effect of the tennis player's hand on the racket's dynamical behavior. For this purpose, a dedicated experimental procedure involving 14 tennis players and 5 tennis rackets has been carried out. Vibrations propagated from the racket toward the upper-limb have been collected synchronously with kinematic and electromyographic data during forehands of various intensities. Additionally, an analytical model of the hand/racket interaction has been designed based on operational modal analyses. This model provides a straightforward tool to predict changes in the dynamical behavior of a tennis racket under playing conditions. Results indicated that tennis players adjust their grip-force to tune the vibrational content entering into his upper-limb. Besides, a noteworthy outcome is that grip-force induces modifications in the racket's dynamical behavior that are at least as important as the differences observed under free boundary conditions due to the rackets' own mechanical parameters.
Transcription and forced alignment of the digital archive of southern speech
Authors: Renwick Margaret E. , Olsen Michael , Olsen Rachel M. , Stanley Joseph A.
Published: June 2017

We describe transcription and forced alignment of the Digital Archive of Southern Speech (DASS), a project that will provide a large corpus of historical, semi-spontaneous Southern speech for acoustic analysis. 372 hours of recordings (64 interviews) comprise a subset of the Linguistic Atlas of the Gulf States, an extensive dialect study of 1121 speakers conducted across eight southern U.S. states from 1968 to 1983. Manual orthographic transcription of full DASS interviews is carried out according to in-house guidelines that ensure consistency across files and transcribers. Separate codes are used for the interviewee, interviewer, non-speech, overlapping, and unintelligible speech. Transcriber output is converted to Praat TextGrids using LaBB-CAT, a tool for maintaining large speech corpora. TextGrids containing only the interviewee’s speech are generated, and subjected to forced alignment by DARLA, which accommodates the levels of variation and noise in the DASS files with a high degree of success. Toward acoustic analysis, we evaluate three methods for vowel formant extraction: the native output of DARLA, a local implementation of FAVE-Extract, and a Praat-based extractor that incorporates separate formant tracks for different regions of the vowel space. We present this workflow of transcription and analysis to benefit other projects of similar size and scope.
An acoustic perspective on legacy data: Vowels in the digital archive of Southern speech
Authors: Renwick Margaret E. , Stanley Joseph A.
Published: June 2017

Speech varies widely in the American South, but the region is argued to share the Southern Vowel Shift, whose various characteristics include monophthongization of upgliding diphthongs, convergence of certain front vowels via raising and lowering, and back-vowel fronting. We investigate the influence of social factors on shift participation using vowel formant and duration data from the Digital Archive of Southern Speech (recorded 1968−1983), which is newly transcribed and segmented by forced alignment. With this corpus of 64 linguistic interviews (372 hours), we study how shifting varies in geographic space, across states from Texas to Florida. The interviews offer large amounts of data from individual speakers, and their semi-spontaneous nature reveals a more realistic portrait of phonetic variability than is typically available. Interviews of European- and African American speakers permit comparison of the Southern Vowel Shift with the African American Vowel Shift. The impacts of other factors on the vowel space are evaluated including generation, gender, socioeconomic status, and education level. Acoustic analysis of historical speech corpora offers perspective for modern sociophonetic studies, by providing a point of comparison to illuminate the development of modern regional variation, which will inform and enhance models of language change over time.
Cross-register speaker identification: The case of infant and adult directed speech
Authors: Kathiresan Thayabaran , Dellwo Volker , Daum Moritz , Shi Rushen
Published: June 2017

The performance of automatic speaker recognition (ASR) systems decreases when training and test data are produced in different social situations (speech registers). The present research tested ASR performance across adult- and infant-directed speech registers (ADS and IDS respectively). IDS compared to ADS is generally characterized by higher and more variable F0, hyper-articulated vowels and higher segment duration and variability. Our dataset consisted of 12 sentences read by 10 Swiss-German mothers to their infants (IDS register) and to an adult experimenter (ADS register). ASR was performed when training and test registers were the same (within register) and when they varied (between register) in 3 experiments. Experiment I used segmental features such as MFCCs and their deltas. Results revealed considerable recognition rate within register (87%) that dropped to about half between registers (44%). This suggests that the variability between IDS and ADS poses challenges on ASR. Experiment II (in progress) uses prosodic features such as F0 statistics, local and long term variations of F0, intensity variations and energy of the frame for the identification. In experiment III, segmental and prosodic features are combined to model the classifier for the identification done in the previous experiments.
Effects of age, sex, context, and lexicality on hyperarticulation of Korean fricatives
Authors: Chang Charles B. , Jeon Hae-Sung
Published: June 2017

Seoul Korean is known for a rare three-way laryngeal contrast among lenis, fortis, and aspirated voiceless stops, which has recently undergone a change in phonetic implementation: whereas older speakers rely more on voice onset time (VOT) to distinguish lenis and aspirated stops, younger speakers rely more on onset fundamental frequency (f0) in the following vowel. This production difference is reflected in disparate strategies for enhancing the contrast in clear speech, supporting the view that younger and older speakers represent the three laryngeal categories differently in terms of VOT and f0 targets (Kang & Guion, 2008). In the current study, we used the clear speech paradigm to test for change in the representation of the two-way contrast between fortis (/s*/) and non-fortis (/s/) fricatives. Native Seoul Korean speakers (n = 32), representing two generations and both sexes, were recorded producing the coronal stops and fricatives in different vowel contexts, item types (real vs. nonce words), and speech registers (plain citation vs. clear). We report acoustic data on how the above factors influence production of the fricative contrast and discuss implications for the phonological categorization of non-fortis /s/ as lenis, aspirated, or a hybrid lenis-aspirated category.
Comparison of beamforming methods to reconstruct extended, partially-correlated sources
Authors: Harker Blaine M. , Gee Kent L. , Neilsen Tracianne B. , Wall Alan T.
Published: June 2017

Advanced cross-beamforming methods improve upon traditional beamforming to reconstruct complex source information and to estimate their respective acoustic radiation. Regularization of the cross-beamforming matrix as part of the calculation procedure helps improve method robustness, but differences in implementation impact volume velocity source results and subsequent field predictions. This paper compares the abilities of four regularization-based, cross-beamforming methods: hybrid method, functional beamforming, generalized inverse beamforming, and mapping of acoustic sources (MACS), along with ordinary cross beamforming, in their ability to reproduce source and field characteristics for an extended, partially correlated numerical source that mimics key characteristics of supersonic jet noise radiation. The four methods that rely on regularization significantly outperform cross-beamforming results, yet the effectiveness of each of four methods is dependent on the individual regularization schemes, which depend on frequency as well as the signal-to-noise ratio. Within those methods, generalized inverse method shows the greatest resistance to regularization variability when comparing results to benchmark cases, although in many cases the hybrid method can give slight improvements. The successful application of the methods demonstrates the utility of cross-beamforming in formulating equivalent source models for accurate field prediction of complex sources, including jet noise. [Work supported by ONR and USAFRL through ORISE.]
Measurement extension limits of patch nearfield acoustic holography
Authors: Chelliah Kanthasamy , Muehleisen Ralph T.
Published: June 2017

Patch nearfield acoustic holography is widely used when the measurement aperture is smaller than the area of the sound source. This paper discusses the factors affecting the limit of aperture extension. One step patch nearfield acoustic holography based on equivalent sources model was considered in this study. Available literature provide constant estimations on the ratio of measurement area to the area of the source. However, the present study shows that this extension limit is a variable depending on a few parameters. Wave number, hologram distance and choice of regularization technique were found to affect the extended area of reconstruction significantly. By choosing the right combination of these parameters, accurate reconstructions were achieved even when the measurement area was only ten percent of the source surface in size. This paper provides a systematic comparison of reconstruction errors for cases with various parameter combinations. A model relating the parameters and the extension limit is under development.
Model-matching for impulse sound localization in urban areas
Authors: Cheinet Sylvain , Ehrhardt Loic
Published: June 2017

The presentation addresses the localization of a punctual, impulse sound source with distributed sensors in an urban area of typical size 150mx150m. In the considered approach, the source is localized by matching some observed characteristics of the signals (here, the first times-of-arrival) to those obtained from a pre-defined database of simulations with known source positions. The localization performance is analyzed on the basis of small-scale model and real-scale measurements, with various building heights, source positions, combinations from 15 down to 5 microphones. The time matching localization attains an accuracy of 10 m in the vast majority of the configurations. A confidence level for each localization is satisfactorily tested. The robustness to the buildings height and to the urban map is evaluated. Adaptations of the approach to real-time constraints and to shot and shooter localizations are demonstrated.
High frequency underwater acoustic communication channel characteristics in the Gulf of Mexico
Authors: Song Aijun
Published: June 2017

In the applications of underwater acoustic communications, higher carrier frequencies support wider bandwidth, which is preferable for achieving higher data rates. At the same time, due to stronger attenuation, higher frequencies lead to shorter communication ranges. During past decades, a large number of efforts were devoted to investigate acoustic communications for the band of 8-50 kHz, over the medium range of several kilometers and beyond. Several efforts focused on the very high frequencies, greater than 200 kHz, for short communication ranges, tens or hundreds of meters. Here we consider a frequency band that falls between the well-studied high frequencies 8-50 kHz, for example from the Kauai Island experiment series, and the “unknown” very high frequencies (200 kHz or higher). A high frequency acoustic experiment was conducted in the northern Gulf of Mexico in August, 2016 to examine the operating ranges, data rates, and performance of acoustic communication systems at the carrier frequencies of 85 and 160 kHz. The received signal-to-noise ratios, channel coherence, and impulse responses will be reported between multiple transducers and a five-element hydrophone array. Communication performance will be reported as well.
Vertical multiuser communication using adaptive time reversal
Authors: SHIMURA Takuya , Kida Yukihiro , Deguchi Mitsuyasu
Published: June 2017

Time reversal is an attractive solution to achieve channel equalization in a rich multipath environment such as underwater acoustic communication (UAC) channel because of its spatial and temporal focusing effect. Recently, demands for multiuser communication have increased in the field of UAC. In Japan Agency Marine-Earth Science and Technology (JAMSTEC), multiple autonomous underwater vehicles (AUVs) operation is planned to widen observation area. Adaptive time reversal is a method for space division multiplexing (SDM) based on its spatial focusing and nulling effect, and a promising solution for multiuser communication. In previous studies, it has been demonstrated that adaptive time reversal is very effective for “horizontal” multiuser communication, in which signals from multiple sources are received vertical receiver array. In this study, adaptive time reversal is applied for “vertical” multiuser communication, which is between a support vessel and multiple vehicles below the vessel. At-sea experiments were carried out in which signals from two sources near the seabed were measured at the receivers on the bottom of the research vessel. As results, adaptive time reversal is also effective for such vertical multiuser communication and has better performance than orthogonal frequency-division multiplexing (OFDM) with SDM combiners.
Iterative source-range estimation in a sloping-bottom shallow-water waveguide using the generalized array invariant
Authors: Cho Chomgun , Song Hee-Chun , Hursky Paul , Jesus Sergio
Published: June 2017

The array invariant proposed for robust source-range estimation in shallow water is based on the dispersion characteristics in ideal waveguides, utilizing multiple arrivals separated in beam angle and travel time for broadband signals. Recently, the array invariant was extended to general waveguides by incorporating the waveguide invariant β, referred to as a generalized array invariant. In range-dependent environments with a sloping bottom, the waveguide invariant β is approximately proportional to the source range via the water depth. Assuming knowledge of the bottom slope, the array invariant can be applied iteratively starting with β = 1 in shallow water, which converges toward the correct source range in a zigzag fashion. The iterative array invariant approach is demonstrated in a sloping-bottom shallow-water waveguide using a short-aperture vertical array (2.8 m) from the Random Array of Drifting Acoustic Receivers 2007 experiment (RADAR07), where a high-frequency source (2-3.5 kHz) close to the surface (6-m) was towed between 0.5 to 5 km in range with the corresponding water depth being 80 and 50 m, respectively.
Archaeoacoustic guidelines. Preparation, execution, and documentation
Authors: Thomas David N.
Published: June 2017

Preparation A discussion of Archaeological theory and archaeoacoustics in a post processual era. The author considers the goals and objectives of archaeoacoustic research in the light of current trends; the nature of the human perception of sound is discussed in the light of the philosophical discussions of “Intentionality.” The importance of a preliminary model displaying accurate reproduction of the resonant space, and use of light as indicator of sound wave propagation is emphasized (using examples from previously published Mousa broch and Minehowe papers). Execution Notes on practical considerations in the field. Equipment, sound makers, recording audio and image photos, tools, and markers. Mic and source recording locations. Wind noise and soundscapes. Notes on theoretical considerations in the field. Sound wave length and the word frequency, the myth of infrasound, and discrete echoes. Documentation Notes on types of documentation. Photo/video record, model record, audio record, and sound analysis. Conclusions, explanations, and possibilities. The implications of applying additional audio recording to illustrate convolution reverbs. Listing and sharing failed approaches. Sharing and Popularization of the discipline of archaeoacoustics.
Temporal soundscape dynamics in a Magellanic penguin colony in Tierra del Fuego
Authors: Francomano Dante , Gottesman Ben , Broadhead Taylor , Pijanowski Bryan C.
Published: June 2017

On Isla Martillo in Tierra del Fuego, we continuously recorded in a colony of Magellanic penguins (Spheniscus magellanicus) in the beginning of the 2016 molting season. Here we describe the daily soundscape dynamics within this colony using existing soundscape metrics, which were originally developed to facilitate acoustic-based ecological inferences from multi-source soundscapes. While these indices have exhibited great successes, little research has explored the utility of soundscape metrics for characterizing ecological patterns and processes when a single soniferous species dominates the soundscape. Bioacoustics offers tools for such applications, but soundscape metrics may be favorable in situations where sounds of chorusing animals temporally overlap or when sounds are non-stereotypical. Some of the diel behavior patterns of this species have been previously documented by studies focusing on foraging behavior, but these studies relied on human observation and dive trackers mounted on individual birds. Instead, we consider the potential utility of terrestrial acoustic recording to monitor populations and behavior of this near-threatened species. We interpret our acoustic data in the context of known Magellanic penguin behavior and the few non-penguin sounds in this habitat, and through this interpretation we evaluate how soundscape metrics can be used to assess nearly monospecific assemblages.
Fish sound production in freshwater habitats of New England: Widespread occurrence of air movements sounds
Authors: Rountree Rodney A. , Juanes Francis , Bolgan Marta
Published: June 2017

We conducted a roving survey of five major river systems and adjacent, creek, lake, and pond habitats located within the northeastern United States. Fish sounds were recorded in 49% of 175 locations. Air movement sounds, including fast repetitive tick (FRT), occurred at 41% of the locations. Sluggish creeks had the highest occurrence of fish sounds (71%). Although highly variable, creeks and brooks had the lowest noise levels and rivers the highest. Fish sounds were more frequent in low noise habitats than high noise habitats, but the effect of masking on detection is not clear. Within main-stem river habitats, fish sound diversity tended to increase along a gradient from high elevation to the sea. Follow-up studies validated air movement sounds produced by alewife, white sucker, and brook, brown and rainbow trout through direct observation or in observations where only single species were present. Sounds produced by all five species are of the “air movement” type which is poorly understood but occurs widely in freshwater habitats. Although air movement sounds are likely incidental to physiological processes, they appear to be uniquely identifiable to species and, hence, hold promise for passive acoustic studies of freshwater soundscapes and fish behavior.
Circular synthetic aperture sonar image resolution theory
Authors: Pailhas Yan , Petillot Yvan
Published: June 2017

The introduction of SAS (Synthetic Aperture Sonar) systems has been a game changer for underwater surveys. The gain in resolution, compared to traditional sidescan systems, created a paradigm shift as the information contained in a SAS image switches from shadows to highlights. SAS systems traditionally perform lawnmower type surveys, but the need for multiple views in MCM (Mine-Counter Measure) tasks, for example, opened the interesting problem of target re-acquisition patterns. In particular, circular patterns maximize the aperture, thus the overall image resolution of such system. The capability of CSAS (Circular SAS) has been demonstrated on the field, but the derivation of CSAS processing has not been fully developed. The non-uniform sampling of the circular pattern in particular introduces aberrations within the field of view and a non uniform PSF (Point Spread Function). In this talk, we propose a new spatial sampling scheme which makes the CSAS PSF perfectly uniform. The theoretical closed form solution of the PSF is then derived both in time and Fourier domain. The PSF derivation naturally leads to redefine the image resolution as an energy leakage problem. Thanks to the new sampling scheme and the uniform PSF, we also propose a deconvolution method based on atom waves which increases the CSAS resolution.
Spatio-temporal variability of bottom reverberation striation pattern in shallow water
Authors: Lunkov Andrey
Published: June 2017

Interference pattern of bottom reverberation can be a source of additional information about underwater environment. Over the last decade, the striations in bottom backscattered broadband signals in the time-frequency domain were observed in several short-term experiments (Goldhahn et al., 2008, Li et al., 2010). In our research, numerical simulations are carried out to analyze the long-term variability of bottom reverberation striation pattern in the presence of internal waves (IW), both background and solitary-like. Coherent normal mode reverberation model is applied. Backscattered chirp signals are selected from different directions by a bottom mounted horizontal array. Simulated striation patterns reveal frequency shifts that are dependent on bearing and IW type. This phenomenon can be used to monitor the spatio-temporal variability of IW. To increase the sensitivity of this approach, the time-reversal sound focusing on the seafloor is proposed. [Work supported by RFBR, 16-32-60194.]
Basic ultrasonic field measurement: Overview of standardized methods and expected developments
Authors: Wilkens Volker
Published: June 2017

Basic ultrasonic field measurement methods to support the acoustic output characterization of medical ultrasound equipment are standardized in IEC 61161 for ultrasonic power by means of radiation force balance measurements and in IEC 62127-1,2,3 for ultrasonic pressure using hydrophones. Descriptions and requirements for ultrasonic power determination seem to be broadly elaborated even, for instance, for extended frequency ranges of high frequency diagnostic systems or for very high output powers of high intensity therapeutic ultrasound devices. In contrast, hydrophone measurements often are accompanied by several challenges still not fully addressed by current standards. Important deficiencies to overcome in future editions are the frequency range of calibrations currently limited to 40 MHz and being insufficient for broadband waveform deconvolution applications, and the descriptions of deconvolution and of the corresponding measurement uncertainty determination themselves. Improvements of these technical items according to recently developed calibration and data evaluation procedures are expected to result in better quality and reliability of acoustic output parameter determination as required, for instance, for diagnostic ultrasound machines within the output declaration and output display according to IEC 60601-2-37 and IEC 62359. In addition, new projects on standards in the high intensity therapeutic area may also take advantage of such improvements.
A quick and reliable acoustic calibration method for a clinical magnetic resonance guided high-intensity focused ultrasound system
Authors: Kothapalli Satya V.V. N. , Partanen Ari , Altman Michael , Wang Zhaorui , Gach H. Michael , Straube William , Hallahan Dennis , Chen Hong
Published: June 2017

With the expanding use and applications of MR-HIFU in both thermal-based and pressure-based therapies, there is an urgent need to develop acoustic field characterization and quality assurance (QA) tools for MR-HIFU systems. We developed a method for quick and reliable acoustic field assessment inside the magnet bore of a clinical MRI system. A fiber-optic hydrophone with a 2-m long fiber was fixed inside a water tank that was placed on the HIFU table above the acoustic window. The long fiber allowed the MRI-incompatible hydrophone control unit to be located outside the MRI suite. MR images of the fiber were used to position the HIFU focus approximately at the tip of the fiber. The HIFU focus was electronically steered within a 5×5×5mm3 volume in synchronization with hydrophone measurements. The HIFU focus location was then identified based on the 3D field scans. Peak positive and negative pressures were measured at the focus at various nominal acoustic powers. Furthermore, focus dimensions and spatial peak pulse average intensities were assessed. The results were compared to and were consistent with standard hydrophone measurements outside the MRI suite. This method provides a useful tool for field characterization and QA of MR-HIFU systems.
Toward detection of early apoptosis using labeled microbubbles
Authors: Matula Tom , Kawasumi Masaoki , Rokunohe Daiki , MacConaghy Brian , Brayman Andrew
Published: June 2017

Chemotherapy is useful for treating metastases, but on average only 50% of tumors respond to the initial choice of drug(s). Many patients thus suffer from unnecessary side effects while their tumors continue to grow, until the proper drugs are found. Because most drugs kill cancer cells by inducing apoptosis, detection of apoptosis can be used to assess drug efficacy prior to treatment. Current technologies require large cell numbers and several time points for quantification. We propose a simple drug screening tool to monitor early apoptosis using annexin-V labeled microbubbles. We investigated the parameter space for such a tool with a transparent flow chamber such that the acoustic radiation force would be relatively parallel with the focal plane of the microscope’s objective. An uncalibrated PZT was activated with a small voltage from a function generator (1-10 V, 2 MHz), generating sufficient pressure to displace microbubble-labeled cells. Initial studies focused on detection of labeled leukemia cells (not apoptosis). In one study, labeled and unlabeled cells were mixed together. In another study, labeled cells were mixed with red blood cells. Displacements were measured with or without flow. The results suggest that a microbubble-based drug screening tool can be developed for real-time monitoring of apoptosis.
Role of mannitol on the echogenicity of echogenic liposomes (ELIPs)
Authors: Kumar Krishna N. , Mallik Sanku , Sarkar Kausik
Published: June 2017

Although echogenic liposomes (ELIP), specially prepared lipid-bilayer coated vesicles, have proved quite effective as scatterers, the exact mechanism of their echogenicity is not well understood. However, freeze-drying in presence of mannitol has proved to be a critical component of the elaborate preparation protocol of these ELIPs. Here, we investigate the role played by mannitol in ensuring echogenicity. We investigated mannitol along with other similar sugars, such as sucrose, trehalose, and xylitol. Mannitol when freeze-dried assumes a crystalline state, while other sugars adopt glassy states. Aqueous solutions of each sugar were prepared and freeze-dried. The freeze-dried samples were re-dissolved in water and the scattered response from the solution was measured. While the solution of mannitol was found echogenic, indicating production of bubbles, others were not. If the sample was freeze-thawed before dissolution, it was not echogenic. The crystalline state of the excipient, mannitol, was necessary for echogenicity. Furthermore, other excipients such as glycine and meso-erythritol, which attain crystalline state upon freeze-drying, also were found to give rise to echogenicity in solution. The production of bubbles by crystalline mannitol upon dissolution indicates a possible mechanism of echogenicity of ELIPs.
Integration of focused ultrasound with nanomedicine for brain drug delivery
Authors: Ye Dezhuang , Federico Cinzia , Kapoor Vaishali , Thotala Dinesh , Hallahan Dennis , Azab Abdel Kareem , Chen Hong
Published: June 2017

Nanomedicine is the next-generation technology for cancer therapy. Liposomes are one of such nanomedicine that have well-established clinical applications. However, their large sizes make it challenging to deliver them to the brain due to the existence of the blood-brain barrier (BBB). Previous studies have demonstrated the potential of integrating focused ultrasound (FUS)-induced BBB opening with liposomes for brain drug delivery. However, no study has characterized the spatial distributions of the liposomes and released drugs in the brain parenchyma at a microscopic level after the BBB was disrupted by the FUS. In this study, we manufactured liposomes with a fluorescent dye embedded in the lipid layer and chemotherapeutic drug doxorubicin encapsulated in the core. These liposomes were intravenously injected into the mouse followed by FUS sonication of a targeted brain location in the presence of microbubbles. The mouse brains were coronally sectioned and imaged using fluorescence microscopy. Preliminary results confirmed the successful delivery of doxorubicin to the brain. However, the liposome distribution as indicated by the dye embedded in the lipid shell was not spatially correlated with the distribution of the doxorubicin. Further studies are needed to better understand the mechanism of FUS-enabled liposome delivery.