bluuebunny/crossref_metadata_2025 huggingface dataset:
An evaluation of density estimation methods using a multiyear dataset of localized bowhead whale calls
Authors: Kim Katherine H. , Thomas Len , Marques Tiago A. , Harris Danielle , Oedekoven Cornelia S. , Cheoo Gisela , Thode Aaron , Blackwell Susanna B. , Conrad Alexander
Published: October 2018

For eight years (2007–2014), Greeneridge Sciences deployed, collected, and analyzed an immense passive acoustic dataset to study the response of bowhead whales (Balaena mysticetus) to oil exploration activities along a 280 km swath of the Alaskan Arctic continental shelf. Each year, up to 40 Directional Autonomous Seafloor Acoustic Recorders (DASARs) detected bowhead calls during the whales’ annual fall migration, resulting in over 2.4 million localized calls over the study period. These enormous sample sizes, combined with the unique localization capability of the DASARs, have enabled the investigation and cross-validation of several acoustic density estimation (DE) methods. Here, we compared results among three density estimation methods: (i) direct census, (ii) distance sampling, and (iii) spatially explicit capture recapture (SECR). In the course of our investigation, we encountered and addressed two challenges: (i) how to apply point transect theory to distributed array systems, and (ii) how to implement SECR in situations where detections between sensors are not statistically independent or where false positives exist on single sensors. These density estimates were then used to estimate relative abundance of the Western Arctic bowhead whale population over multiple years. [Work sponsored by the Joint Industry Programme.]
Advances in controlled transcranial bubble-mediated drug delivery and opportunities for transvertebral therapy
Authors: O'Reilly Meaghan A. , Jones Ryan M. , Deng Lulu , Leung Kogee , Fletcher Stecia-Marie P. , Xu Rui , Hynynen Kullervo
Published: October 2018

The treatment of central nervous system (CNS) disorders is hindered by the presence of specialized barriers that maintain the privileged CNS environment and in doing so restrict the transport of molecules from the vascular compartment to the parenchyma. The ability of ultrasound in combination with intravenously administered microbubbles to transiently open the Blood-Brain Barrier (BBB) to permit the delivery of therapeutic agents is well established in preclinical models and has reached the stage of clinical investigations. Although the methods are not yet as developed as those for BBB opening, ultrasound can also modify the Blood-Spinal Cord Barrier (BSCB) to facilitate drug delivery. Both treatments have immense potential to revolutionize the treatment of CNS disorders, but their widespread clinical adoption hinges on the establishment of robust methods to deliver, monitor and control the exposures to ensure safe and effective treatments in these sensitive tissues. This talk will present recent advances in methods for brain therapy, including three-dimensional transcranial microbubble mapping for treatment control, and will also present new preclinical findings in BSCB opening and approaches for controlled transvertebral focusing at clinical scale.
Investigating the role of lipid transfer in sonoporation
Authors: Aron Miles , Vince Oliver , Gray Michael , Stride Eleanor P.
Published: October 2018

The permeabilisation of cell membranes following exposure to microbubbles and ultrasound has considerable potential for therapeutic delivery. Recent studies have demonstrated that transfer of material takes place between phospholipid-coated microbubbles and cell membranes. The aim of this study was to investigate the impact of this transfer on membrane properties and cell permeability. Microbubbles were prepared with matched concentrations and size distributions from a series of formulations utilising phospholipids with differing molecular characteristics. Quantitative fluorescence microscopy techniques were used to quantify changes in the molecular packing, viscosity, and permeability to model drugs of cancer cells under mild ultrasound exposure (15 s of 1 MHz centre frequency, 125 kPa peak negative pressure, 1 kHz pulse repetition frequency, and 10% duty cycle). The molecular “packing” of cancer cell membranes was found to be significantly affected by the transfer of both phospholipids and other microbubble coating constituents. This was particularly pronounced in the case of microbubbles containing a specific class of lipids, which promoted a ~4-fold increase in model drug uptake following ultrasound exposure. Similar results were observed in an investigation of permeability in an in vitro blood brain barrier model suggesting that microbubble composition may play a key role in the efficacy of ultrasound mediated delivery.
High-precision acoustic measurements of the non-linear dilatational elasticity of phospholipid-coated monodisperse microbubbles
Authors: Segers Tim , Gaud Emmanuel , Versluis Michel , Frinking Peter
Published: October 2018

The acoustic response of phospholipid-coated microbubble ultrasound contrast agents (UCA) is dramatically affected by their stabilizing shell. The interfacial shell elasticity increases the resonance frequency, the shell viscosity increases damping, and its nonlinear behavior increases the generation of harmonic echoes that are routinely used in contrast-enhanced ultrasound imaging. To date, the surface area-dependent interfacial properties of the phospholipid coating have never been measured due to the extremely short time scales of the MHz frequencies at which the microscopic bubbles are driven. Here, we present, high-precision acoustic measurements of the dilatational nonlinear viscoelastic shell properties of phospholipid-coated microbubbles. These highly accurate measurements are now accessible by tuning the surface dilatation of well-controlled monodisperse bubble suspensions through the ambient pressure. Upon compression, the shell elasticity of bubbles coated with DPPC and DPPE-PEG5000 was found to increase up to an elasticity of 0.6 N/m after which the monolayer collapses and the elasticity vanishes. During bubble expansion, the elasticity drops monotonically in two stages, first to an elasticity of 0.35 N/m, and then more rapidly to zero. Integration of the elasticity vs. surface area curves showed, indeed, that a phospholipid-coated microbubble is in a tensionless state upon compression, and that it reaches the interfacial tension of the surrounding medium upon expansion.
Antibody targeted ultrasound-responsive nanodroplets for the therapy of brain metastases: A pre-clinical study
Authors: Vince Oliver , Bau Luca , Peeters Sarah , Gray Michael , Richards Luke , Smart Sean , Sibson Nicola , Stride Eleanor P.
Published: October 2018

Metastatic tumors in the brain represent one of the leading causes of death from cancer with current treatments being largely ineffective and/or associated with significant side effects due to their lack of targeting. Conjugating MRI contrast agents with a monoclonal antibody for VCAM1 (anti-VCAM1) has previously allowed detection of brain tumor volumes two to three orders of magnitude smaller than those volumes currently detectable clinically. In this study, a novel magnetic and acoustically responsive phospholipid-stabilised nanodroplet formulation has been conjugated with anti-VCAM-1. Preliminary in vivo tests have shown that these anti-VCAM-1 nanodroplets can be successfully targeted to both inflamed areas of the brain and metastatic brain tumours. Acoustic droplet vaporisation of the anti-VCAM1 droplets, confirmed by passive cavitation detection, was also shown to cause blood brain barrier permeabilisation in vivo. Extensive in vitro characterisation of the potential of these nanodroplets to target brain metastases using antibody and magnetic targeting, along with the ultrasound conditions required for various therapeutic effects has been completed and has been found to agree well with mathematical modelling. The implications of these findings and the plans for future investigations into the therapeutic potential of these targeted and ultrasound responsive agents will be discussed.
High-speed observations of Acoustic Cluster Therapy “activation” and “therapy”
Authors: Song Jae Hee , Healey Andrew , Prentice Paul
Published: October 2018

Acoustic Cluster Therapy (ACTTM) is a novel and versatile drug delivery platform, based on electrostatically bound clusters of negatively charged contrast agent microbubbles (SonazoidTM, GE Healthcare) and positively charged oil microdroplets, for co-administration with drug to the vasculature. Preliminary in-vitro high-speed observations at up to 10 million frames per second of both “activation” (exposure of clusters to 2.19 MHz focused ultrasound, at mechanical index, MI ≈ 0.15) and “therapy” (exposure of the resulting vapour bubbles, to 675 kHz with MI ranging from 0.1 to 0.4) will be presented. At low MI, the therapy exposure induces quasi-linear oscillations of the vapour bubble, with higher MIs inducing high-order surface wave activity. In the latter case, the amplitude of the non-spherical oscillations increase during the exposure until involutions neck, generating intra-bubble droplets that traverse the bubble core at speeds of up to several m/s. Possible mechanisms for activation and therapy will be discussed, based on the observations. [This research was supported by ERC Starting Grant TheraCav, 336189, and Glasgow Knowledge Exchange project DefACT.]
Airborne vector sensor experiments within an anechoic chamber
Authors: Dall'Osto David R. , Dahl Peter H. , Alberts W. C. Kirkpatrick , Scanlon Michael V.
Published: October 2018

A technique to measure acoustic particle velocity in air is demonstrated in a controlled set of experiments conducted within an anechoic chamber at the Army Research Lab (ARL-Adelphi). This air-borne vector sensor measures acoustic pressure with an omnidirectional microphone and the 3D acceleration of a lightweight, rigid sphere with an embedded high-sensitivity tri-axial accelerometer. Two experiments are presented to demonstrate fundamental properties of the acoustic vector field: sound directionality, and the relative phase of pressure and particle velocity in the near to far field transition. Directional studies are implemented in the far-field of a speaker producing tones, defined by kr>>1, where r is the range from the speaker and k is the acoustic wavenumber. The pressure-velocity phase relationship is examined through the transition kr << 1, kr = 1, and then kr >> 1 by changing frequency and sensor range. For comparison, a tri-axial Microflown sensor simultaneously recorded the acoustic field. As neither sensor measures particle velocity directly, the phase characteristics of sensors depend on the sensing technique and corrections must be made to account for the true phase of particle velocity. Advantages and disadvantages of each method are discussed.
Localizing multiple targets with a single particle velocity sensor
Authors: Tran-Luu Tung-Duong , Dao Minh
Published: October 2018

The acoustic velocity sensor (AVS) measures the direction of a propagating plane wave by measuring instantaneously the particle velocity over a small volume in space. When multiple sound sources are present, the AVS no longer reports the correct directions as the sound intensity vectors (the product of pressure and velocity vector) get mixed up nonlinearly. A few methods have been proposed to extract the individual components from just one sensor by assuming, for example, spectral separability or nongaussianity. This paper shows it is in fact possible to extract the components without making such assumptions. The approach here is to constrain the signal with the acoustic impedance equation for multiple superposing plane waves and, applying various techniques, such as sparsity decomposition, to solve the derived least squares problem.
Source localization using back propagation neural network and a single vector receiver
Authors: Wang Wenbo , Su Lin , Ma Li , Ren Qunyan
Published: October 2018

Matched field processing (MFP) has been widely used in source localization in shallow waters, whose performance is strongly correlated with the knowledge of environmental properties and proper selection of sound propagation model. This paper presents a neural network based approach for source ranging of moving target, which does not need heavy sound field calculation and no requirement of environmental information as a known prior. This neural network is designed to determine source range by observing multiple-frequency sound fields as excited by the source and recorded on a single vector receiver. In synthetic tests, this neural network is first trained on training data set as to adaptively select the optimal features through error back propagation, and then its localization performance is validated on testing data set. This approach is then tested on ship noise data as collected by a single vector sensor, and the relative error is smaller than 0.1 through comparing to GPS calculations. The promising results suggest the proposed approach can be further developed for source ranging applications with light system.
Nonlinear tuning curve vibration using a column of non-wetted or wetted glass beads vibrating over a clamped elastic plate: Case for air-borne sound excitation
Authors: Santos Emily V. , Korman Murray S.
Published: October 2018

A soil plate oscillator (SPO) apparatus consists of two circular flanges sandwiching and clamping a thin circular elastic plate. The apparatus can model certain aspects of the nonlinear acoustic landmine detection problem which involves the interaction of granular material with an elastic plate in flexural vibration. Uniform spherical glass beads—representing a nonlinear mesoscopic elastic material—are supported at the bottom by the acrylic plate (4.5 inch diam, 1/8 inch thick) and stiff cylindrical sidewalls of the upper flange. Two 3 in. diam loud speakers placed above the bead column are driven with a swept sinusoidal signal applied to a constant current amplifier to generate air-borne sound excitation from 50 to 1250 Hz. A small accelerometer fastened to the underside of the plate at the center measures the response. Separate tuning curve experiments are performed using a fixed column of 350 grams using 2,3,…,10 mm diameter soda-lime glass beads—wetted or non-wetted (mineral-oil). With dry beads, backbone curves (peak acceleration vs. corresponding resonant frequency) exhibit a linear region with comparable slopes, while detailed back-bone curvature vs. bead diameter reveals more structure. Wet beads exhibit less non-linear tuning curve behavior.
Information retrieval from a soundscape by using blind source separation and clustering
Authors: Lin Tzu-Hao , Tsao Yu , Akamatsu Tomonari , Tuanmu Mao-Ning , Fujikura Katsunori
Published: October 2018

Passive acoustic monitoring represents one of the remote sensing platforms of biodiversity. However, it remains challenging to retrieve meaningful biological information from a large amount of soundscape data when a comprehensive recognition database is not available. To overcome this issue, it is necessary to investigate the basic structure of a soundscape and subsequently retrieve biological information. The recent development of machine learning-based blind source separation techniques allow us to separate biological choruses and non-biological sounds appearing on a long-term spectrogram. After the blind source separation, the temporal-spatial changes of bioacoustic activities can be efficiently investigated by using a clustering algorithm. In this presentation, we will demonstrate the information retrieval in the forest and marine soundscapes. The separation result shows that in addition to biological information, we can also extract information relevant to weather patterns and human activities. Furthermore, the clustering result can be used to establish an audio library of nature soundscapes, which may facilitate the investigation of interactions among wildlife, climate change, and human development. In the future, the soundscape-based ecosystem monitoring will be feasible if we can integrate the soundscape information retrieval in a large-scale soundscape monitoring network.
Audible noise sources (or characteristics?) from wind turbines using acoustic beam-forming
Authors: Metelka Andy
Published: October 2018

In many investigations of wind turbine noise, residents report specific and varying types of audible characteristics. With respect to the subject audible characteristics reported by residents (which are not picked in the dBA Leq measurements) turbines exhibit multiple audible sources at different operating and environmental conditions. Imaging techniques for real-time noise source identification have been used to identify tonal as well as dynamic pulsation during various environmental conditions and distances. Challenges with these techniques are presented using advanced imaging algorithms with successful imaging.
Existing aeroacoustic issues of building elements
Authors: Bolduc Michael , Bell Andrew
Published: October 2018

During high wind events, certain building elements have the potential to generate significant tonal noise that can be heard miles away. These aeroacoustic issues are due to an interaction/coupling between an unstable fluid flow and a feedback mechanism, usually being a resonant acoustic mode. Aeroacoustic issues are often easy to avoid when susceptible geometry can be identified during the early design process, but mitigation can be technically difficult and very costly once issues do occur. Because aeroacoustic issues are unique and often annoying, they are often considered newsworthy and can be the subject of significant publicity. A series of case studies of existing structures, which have experienced aeroacoustic problems from their surrounding wind climate, are presented. Through each of these case studies, the steps used to identify suspect features and the recommended remedial measures are presented. The methodology for identification of the suspect feature may include investigating trends in weather data, conducting spectral analysis of audio recordings, performing calculations of the natural frequencies of building features, and on-site observations and measurements. Various mitigation strategies are detailed, depending on the mechanism found to be generating the aeroacoustic noise.
On the uncertainty principle for the pitch of brief tones
Authors: Hartmann William M. , Pumplin Jon
Published: October 2018

Many experiments have shown that the ability of human listeners to discriminate the frequencies of brief tones can violate the wave uncertainty principle that applies to linear systems. Several observations can be made: (1) Experiments that associate the duration of the tone envelope, or the second central moment of the squared envelope, with temporal uncertainty are consistent with the application of the energy-time principle in non-relativistic quantum mechanics. (2) The role of echoic memory in confounding the definition of duration can be avoided by immediately following the target tone to be judged by a tone of different frequency. (3) Whereas the uncertainty principle relates well-defined conjugate variables, such as time and frequency, listeners in psychoacoustical experiments may benefit from comparisons in both the pitch dimension (coding frequency) and a timbral dimension associated with the spectral distribution of energy. The latter provides additional information that is outside the context for the uncertainty principle. Its influence can be reduced by experiments in which the listener compares target tones having different brief durations. When these considerations are applied, it is found that human listeners still beat the uncertainty principle, but not as impressively.
Determining acoustic sound power using vibration measurements and acoustic radiation modes
Authors: Goates Caleb B. , Jones Cameron B. , Sommerfeldt Scott D. , Blotter Jonathan
Published: October 2018

In this paper, an efficient method for measuring the radiated sound power from consumer, industrial, and military products is presented. The method is based on spatially-dense vibration measurements from a 3D laser vibrometer and the acoustic radiation modes approach for computing sound power. The method will be a design tool that will allow engineers and designers to design quieter products by more effectively using noise as a design constraint. There are several standards that describe methods to compute sound power but these methods typically require specialized acoustic chambers for high accuracy results. The method presented here can be performed in an unknown acoustic environment without a reflective surface or an array of specific measurement points surrounding or half surrounding the noise source. The method will also be insensitive to varying background noise, temperature, and fluid/wind flow. The method will provide near real-time results and will be capable of measuring the radiated sound power from complex 3D geometries and built-up structures or parts of these structures. The method will presented in detail with experimental results validated the process.
Experimental and numerical techniques for lightweight vehicle sound package development
Authors: Gur Yuksel
Published: October 2018

The use of lightweight structural materials poses great challenge to noise control of a vehicle. A new approach to sound package design in lightweight vehicles was developed to reduce vehicle interior noise level without addition of weight. This new approach relies on lightweight acoustical materials that provide superior sound absorption performance to reduce noise level at the source, e.g., inside engine compartment and near the tires. Vehicle NVH finite element analysis (FEA) models were used to develop the lightweight vehicle’s structural design to bring the lightweight vehicle’s low and mid frequency responses closer the baseline vehicle’s performance. Full vehicle SEA (statistical energy analysis) model was developed to evaluate the high frequency NVH (noise, vibration, and harshness) performance of a vehicle. This correlated SEA model was used for the vehicle sound package optimization studies to develop sound package design to improve lightweight vehicle’s acoustic performance. In this paper, the use of NVH CAE (computer aided engineering) simulations for lightweight vehicle design is presented to highlight the limitation and use of FEA and SEA in lightweight vehicle development.
English phoneme recognition of vocoded speech by adult Mandarin-speaking English-learners
Authors: Yang Jing , Xu Li
Published: October 2018

The present study examined the joint influence of listeners’ language experience and the degree of spectral degradation of speech signals on English phoneme recognition of L2 listeners. The participants included 27 native English-speaking listeners and 43 native Mandarin-speaking listeners who used English as an L2. The L2 participants varied in chronological age, age of English learning, length of residency in the United States, and the amount of daily-based English usage. The speech stimuli included 12 English vowels embedded in a /hVd/ context produced by four speakers and 20 English consonants embedded in a /Ca/ context produced by two speakers. The speech stimuli were processed using 2-, 4-, 6-, 8-, and 12-channel noise vocoders. The processed and original stimuli were presented to the listeners for identification in a random order. The results showed that spectral degradation had more adverse effects on the L2 listeners but the L2 disadvantage became more evident as the number of frequency increased. The L2 listeners showed different confusion patterns from the L1 listeners, which was affected by the L2 listeners’ native language experience. Furthermore, the regression analysis revealed that the L2 listener’s length of residency in the United States was a significant predictor for their phoneme recognition outcomes.
Non-native perception of regionally accented speech of competing talkers
Authors: Jacewicz Ewa , Kim Sasha , Fox Robert A.
Published: October 2018

Noisy conditions are challenging to non-native listeners who typically underperform relative to native listeners when attending to several competing talkers. We examine whether non-native listeners can utilize dialect-related cues in the target and in the masking speech, even if they do not reach the proficiency level of the native listeners. Our previous work with highly proficient Indonesian-English bilinguals (Fox et al., 2014) found that their performance differed markedly from native English listeners when the speech levels of the competing talkers were equal (0 dB SNR). We hypothesized that bilinguals cannot effectively separate utterances at 0 dB SNR due to a lack of a sufficient contrast in the voice levels of competing talkers, which may reduce their ability to benefit from the phonetic-acoustic details in order to “follow” a particular talker. The current study sought to replicate and validate earlier findings with a different group of bilinguals. The same experiment was conducted with Korean-English bilinguals. The results were replicated, providing further evidence that the ability to benefit from fine-grained phonetic details in regional accents declines for non-native listeners when the speech levels of the competing talkers are equal. Discussion will focus on defining the nature of the non-native speech processing deficit.
Foreign accent in L2 Japanese: A cross-sectional study
Authors: Idemaru Kaori , Tsukada Kimiko , Kato Misaki
Published: October 2018

The current study examines acoustic sources of foreign accent in second language Japanese produced by American learners across different instructional levels and learning backgrounds. Our prior work has demonstrated that pitch accent, vowel duration, and spectral information of the vowel [e] influence perceived foreign accent in Japanese short sentences produced by intermediate learners, with pitch accent exerting the strongest influence. Building on this prior finding, the current study examines Japanese produced by American learners at the beginning level (n = 10), at the intermediate level (n = 16), American learners who have had early exposure to Japanese (n = 10), native Japanese speakers (n = 10), and ratings of the speech samples by native Japanese listeners (n = 10) to investigate the difference in the extent of perceived accent in their speech and the acoustic sources that influence perceived accent. The results of the current study shed light on issues related to development of second language speech, and the perceptual relevance of the development to lay listeners.
Comprehension of accented sentences by young and older listeners
Authors: Lin Yu-Jung
Published: October 2018

Previous studies have shown that understanding accented speech requires additional cognitive support. Along this line, the current study aims to test whether the ability to understand accented speech can be influenced by aging and whether older listeners are more sensitive to accented speech. Native speakers of Southern Min from two age groups (18–35, 55 and older) are instructed to listen to sentences produced by two groups of speakers, native and nonnative speakers of Southern Min, answer questions regarding the target words in the sentences produced by these speakers, and then rate speakers' comprehensibility and accentedness. The stimuli for the listening test are produced by speakers during a delayed repetition task, where they repeat the Southern Min sentences after hearing each of them. The target words embedded in these sentences contain phonemes known to be difficult for nonnative speakers (e.g., syllable-initial voiced stops, nasalized vowels). It is hypothesized that older group, compared to younger listeners, will score lower on understanding accented speech, and tend to rate more speech accented and rate less speech comprehensible.
Perception of spectrally-shifted non-native speech
Authors: Kapolowicz Michelle R. , Guest Daniel , Montazeri Vahid , Baese-Berk Melissa M. , Assmann Peter F.
Published: October 2018

Some studies have suggested that perceiving speech from multiple non-native talkers can be more difficult than perceiving speech from a single non-native talker. We found evidence in favor of this idea, previously showing a detrimental effect on sentence intelligibility of reducing the spectral resolution of non-native speech via a 9-channel tone vocoder (a condition where talker-specific spectral cues are limited). This effect was more severe when perceiving non-native speech from multiple talkers compared to a single talker, whereas we observed no differences across single- and multiple- native talker conditions. These results imply that listeners place greater reliance on talker-specific spectral cues to aid with perception of non-native speech as compared to native speech. In the present study, we further examined the effects of talker-specific spectral cues on intelligibility by scaling the spectral envelope and fundamental frequency (F0) of previously recorded sentences in successive increments of 8% and 30%, respectively, using the STRAIGHT vocoder. As predicted, intelligibility of spectrally-shifted sentences spoken from a single, non-native talker was similar to that observed for multiple non-native talkers, and listeners reported hearing spectrally-shifted speech as coming from different talkers. These results confirm the importance of spectral cues for the perception of non-native speech.
The effectiveness of audio-visual training on non-native English speech production and perception
Authors: Shen Chia-Ni , Baese-Berk Melissa M.
Published: October 2018

This project examines the effectiveness of audio-visual training on non-native English speech production and perception. Previous research utilizing audio-visual training has been employed in the field of speech pathology, showing positive outcomes in improving speech among dyslexic children. However, few studies to date have examined its use in second language learning, specifically bilabial and labiodental consonants (i.e., /b, p, m, f, v/), which are known to be challenging for many second language learners. The aim of this project is to explore audio-visual training across 3 native language groups, Mandarin Chinese, Japanese, and Arabic, who are all English language learners. Participants undergo a training regimen designed to examine the effects of audio-visual and audio-only training. Performance before and after training is assessed via perception and production tests. We hypothesize that 1) production and perception performance will improve after two days of training and will improve more after audio-visual training and 2) production and perception improvement will rely heavily on a participants’ language background and known difficulties with specific bilabial and labiodental sounds. Results from this study will enrich understanding of the effectiveness of audio-visual training in second language learning.
Compressed sensing and recovery of underwater acoustic signal in Internet of Things
Authors: Wu Feiyun , Yang Kunde , Sun Quan , Zhu Yunchao
Published: October 2018

Telemonitoring and communications technologies of underwater information is inseparable from the process of sampling and transmitting of data. Conventional methods often fail in energy efficiency to obtain such a huge data in Internet of Things (IoT), compressed sensing (CS) provides a new perspective to solve the problem. Unfortunately, the underwater acoustic signal is non-sparse in the time domain and thus the current CS methods cannot be used directly. This study adopts the fast Fourier transform (FFT) based dictionary-matrix for sparse representation. Then we design an approach based on an approximated $l0$ (AL0) norm at the receiving terminal, to search the sparse solution via the filtered steepest descent method and projections. The sparse estimation is used for reconstruction of collected data, combing with the previously used measurement matrix and dictionary-matrix. Experimental results confirm the superior performances of the strategies of the proposed method than the traditional methods including matching pursuit (MP) and orthogonal matching pursuit (OMP) methods.
The CCi-MOBILE Vocoder
Authors: Ali Hussnain , Mamun Nursadul , Bruggeman Avamarie , Chandra Shekar Ram Charan M. , Saba Juliana N. , Hansen John H. L.
Published: October 2018

The UT-Dallas Costakis Cochlear Implant Mobile (CCi-MOBILE) research platform enables experimental research with hearing-aid (HA) and cochlear-implant (CI) devices. The platform substitutes the clinical sound processor (CI/HA) with an Android smartphone/tablet or a PC as a computing hardware to run custom speech processing algorithms. The flexibility offered by such a setup enables researchers to provide custom-designed electric and acoustic stimuli (EAS) to CIs and HAs bilaterally in a time-synchronized manner. With this bimodal (electric + acoustic) capability, the platform can be used to undertake studies with individuals who either use a CI in one ear and a HA in the contralateral ear, or use hybrid implants in one or both ears. The CCi-MOBILE software suite includes a range of research applications which address different experimental needs. In the present work, a real-time VOCODER is incorporated in the CCi-MOBILE platform to facilitate research involving acoustic simulations of CIs. Two traditional flavors of VOCODER processing are implemented, namely noise-band and sine-wave vocoding. Flexibility is provided to modify processing parameters such as number of channels, frequency band-widths, filter attributes, etc. This flexibility combined with the ability to conduct long-term studies beyond the laboratory in diverse naturalistic acoustic environments will help advance research in psychoacoustics.
Practical open-concentric spherical microphone array design
Authors: Thomas Mark R.
Published: October 2018

The problem of higher order sound field capture is considered. First-order microphone arrays, such as tetrahedral A-format designs, are commonplace, while interest remains in the increased spatial resolution delivered by higher order arrays. Such arrays typically consist of pressure microphones mounted on a solid spherical baffle, with which higher-order spatial components are estimated algorithmically. This produces a design trade-off, with small arrays being preferred for spatial aliasing performance and large arrays being preferred for reduced amplification of microphone capsule noise at low frequencies. A practical open sphere design is proposed that contains microphones mounted at multiple radii to fulfill both criteria. Coupled with the use of cardioid microphones, such an array captures higher order soundfields over a wider audio bandwidth than baffled spherical designs of fixed radius.
The room impulse response in time, frequency, and space: Mapping spatial energy using spherical array beamforming techniques
Authors: Neal Matthew T. , Vigeant Michelle C.
Published: October 2018

The auditory perception of rooms is a multi-dimensional problem. Our hearing system interprets time, frequency, and spatial information from arriving room reflections, but traditionally, only the time and frequency domains are considered in room acoustic metric and objective sound field analyses. This work aims to develop spatial visualizations of the energy in a room impulse response (RIR). With a spherical microphone array, a room’s energy can be mapped in full three-dimensions. First, beamforming techniques are used to generate a set of directional RIRs from the spherical microphone array measurement. This set of directional RIRs is analogous to using a microphone with a directional beam pattern response, oriented individually at all points around a sphere. Then, these directional or beam RIRs are time windowed and band-pass filtered to create spatial energy maps of the room. Comparisons between a plane-wave beam pattern and a Dolph-Chebyshev beam pattern will be demonstrated in the context of RIR beamforming. As well, different strategies for normalizing peak energy amplitudes to either the direct sound or a spherical spreading condition will be compared. With these considerations, final results of these spatial energy visualizations and directional RIR animations will be demonstrated. [Work supported by NSF Award 1302741.]
Transient solution for the directional response at the focus of a paraboloidal reflector
Authors: Cormack John M. , Hamilton Mark F.
Published: October 2018

A transient solution is presented for the directional response at the focus of a paraboloidal reflector due to an incident plane wave. The validity of the solution is associated with the Kirchhoff approximation used to determine the boundary condition on the surface of the reflector, which requires the wavelengths to be short compared with the minimum radius of curvature of the reflector. The solution at the focus due to an incident plane wave is obtained by applying the principle of reciprocity to the solution in the far field due to a point source at the focus. Both solutions are expressed as the convolution of the unit step response with the time derivative of the waveform incident on the reflector. For a point source far removed from a shallow paraboloidal reflector, it is shown that the pressure in the far field reduces to the expression obtained by Morse (Vibration and Sound) for transient radiation from a baffled circular piston. Results are presented illustrating the angular dependence of the reflected pressure waveforms at the focus for incident plane waves that include a rectangular pulse, an N wave, and a tone burst. [J.M.C. was supported by the ARL:UT McKinney Fellowship in Acoustics.]
Experimental and numerical investigation of backscattered signal strength from different concentrations of nanobubble and microbubble clusters
Authors: Haghi Hossein , Jafari Sojahrood Amin , De Leon Al C. , Exner Agata , Kolios Michael C.
Published: October 2018

Optimizing the clinical performance of Nanobubbles and Microbubbles (MBs and NBs) requires not only a good understanding of their individual bubble dynamics, but how bubble interactions change these dynamics. Here we report our experimental and simulation results showing the changes in backscattered signal strength from different concentrations of NBs or MBs. NBs and MBs are sorted by size to isolate two populations with mean diameters of 200 nm and 1 micron, respectively. Our results show that increasing number density of NBs or MBs is accompanied with an increase in the strength of their backscattered signals up to a certain concentration, above which the strength of the signal decreases. This decrease is not associated with the medium attenuation which was not accounted for. Our numerical simulations that include inter-bubble interactions are in general agreement with our experimental results. Moreover, acquired data show the that concentration at which there is signal saturation for NBs is orders of magnitude higher than that of MBs (1e9 vs 1e6 bubbles per mL), suggesting a potential explanation behind the very strong backscatter observed in NB clusters compared to MBs. Numerical simulations show that increasing the number density of bubbles decreases the individual signal strength of each individual bubbles.
Phase shift nanoemulsions facilitated focused ultrasound nonthermal ablation in mice brain
Authors: Peng Chenguang , Sun Tao , Vykhodtseva Natalia , Zhang Yongzhi , Power Chanikarn , McDannold Nathan , Porter Tyrone M.
Published: October 2018

High intensity focused ultrasound (HIFU) thermal ablation is an emerging technique for noninvasive transcranial surgery. One of the major issues of transcranial HIFU thermal ablation is that the pressure and power required to generate lesions is relatively high and could induce skull heating and pain in some cases. Artificial nuclei like phase shift nanoemulsions (PSNE) have been shown to significantly lower the acoustic pressure and power needed to create lesions through inertial cavitation. However, traditional PSNE made from dodecaperfluoropentane (DDFP) were not able to activate below a peak negative pressure (PNP) of 3.5 MPa, which may be difficult to achieve inside the brain. In this study, we proposed to use a more volatile perfluorocarbon—perfluorobutane (PFB)—to synthesize PSNE so that they could be activated at much lower pressures. A transcranial focused ultrasound transducer operating at 740 kHz and 12 CD-1 mice were used to test the vaporization of PFB PSNE and the corresponding damage. The PNP was increased stepwise up to 1.8 MPa and the broadband emission from the inertial cavitation nucleated by vaporized PFB-based PSNE were recorded to quantify the inertial cavitation level. A significant elevation of broadband emission was noticed first at PNP = 1.25 MPa and increased dramatically, indicating strong inertial cavitation. The corresponding biological damage was analyzed with H&E staining and exhibited confined ischemic and hemorrhagic lesions.
Construction and preliminary studies of the 3-6-(7) tones Oja
Authors: Onwubiko Stephen G. , Neilsen Tracianne B.
Published: October 2018

Common in the eastern parts of Nigeria among Igbos, the oja is a Nigerian wooden flute. More like a whistle with its rich sharp tone, the oja is an end blown flute about 14–16 cm long with a narrowed, hollowed cavity running down its entire length and another across its width. These form three holes that can be covered in various combinations with the fingers of both hands, giving the flute a range of about a sixth or a seventh depending on the master player. The mouthpiece is “U” or “V” shaped. With the three holes, it is expected that there would be three distinct pitches produced from the “oja” but more than three tones can be heard or sounded. This paper showcases the construction of oja flute, and presents preliminary studies on how the sixth can be realized. Pictorials, data, and videos of practical experience are presented to support the theoretical discourse.
Children’s real-time spoken language processing in the presence of background speech
Authors: Grieco-Calub Tina M. , Simeon Katherine M. , Birger Shana
Published: October 2018

Children’s naturalistic environments often contain noise, including background speech and environmental sounds, that disrupts their speed and accuracy of spoken language processing. Integrating congruent auditory and visual speech cues, a skill that improves throughout childhood, facilitates language processing in background noise. The present study implemented an integrated eye-tracking and touch-screen paradigm to explore how children utilize visual speech cues in the presence of background speech and how these behaviors change with age. Typically-developing children (ages 3–12 years), either heard (auditory-only) or heard and viewed (audiovisual) a female speaking sentences (e.g., Find the dog) in quiet or in the presence of a male two-talker speech masker at + 2 dB SPL. Children were then instructed to select an image, among a set of three, that matched the sentence-final word. During each trial, children’s eye gaze was recorded, which allowed us to quantify children’s fixations to the target versus the distractor images. These data enable us to make fine-grained measurements of children’s language processing in real time. Performance was also quantified by accuracy of target image selection. Discussion will focus on children’s spoken language processing in the presence of background speech and in the presence and absence of congruent audiovisual speech cues.
Effects of background noise in vowel productions of children with cochlear implants
Authors: Okalidou Areti , Peng Z. Ellen , Pantazidou Polina , Fels Janina , Nistikakis Michalis , Kyriafinis George
Published: October 2018

Early cochlear implantation led to significant improvements in the speech of deaf children, yet, reduced accuracy and greater token-to-token variability are noted. Vowel spaces are either normal or reduced and vowels are produced with less consistency (e.g., Baudonck et al. 2011; Neumeyer et al. 2010). So far, studies investigated speech in quiet. In the real world, children with cochlear implants (CI) function in noisy environments with auditory feedback containing speech and noise which is known to alter speech production even in typically developing adults (e.g., Bottalico et al., 2015). Since children with CI produce less robust vowels, this study aimed to examine the effects of everyday noise on their productions. Eight children with CI, 6;10–12;0 years old, produced words with Greek vowels while listening to auditory stimuli provided directly via auxiliary input port to the speech processor. The conditions were: a) quiet, b) speech-shaped noise, and c) speech-shaped noise with reverberation. Acoustic measurements of F1 and F2, pitch, duration and intensity were made. Apart from inter-subject variability, results indicated changes in pitch, F1, and intensity with added noise along with occasional changes in duration and F2. Individual analysis focused on age and vowel space changes as the acoustic conditions changed.
Relationship between perception of speech in noise and disordered speech: Influence of sensorineural hearing loss
Authors: Yoho Sarah E. , Borrie Stephanie A.
Published: October 2018

It is well known that there exists substantial individual variability in the ability to understand speech in adverse listening conditions. Despite this variability, a recent study with normal-hearing listeners has revealed a strong relationship between the ability to perceive speech in noise (environmental degradation) and dysarthric speech (source degradation) [Borrie et al., Journal of Acoustical Society of America,141, 4660–4667 (2017)]. While a large body of literature on the difficulty faced by hearing-impaired listeners in understanding speech in noise exists, the difficulties faced by this population in understanding dysarthric speech has received much less attention. Further, investigations into the relationship between processing speech in noise and dysarthric speech for listeners with hearing loss do not exist. This current study extends on previous findings, investigating the relationship between processing speech in noise and dysarthric speech for listeners with sensorineural hearing loss. Preliminary results replicate previous findings of a relationship between the ability to perceive speech in noise and dysarthric speech for normal hearing listeners. This relationship is also observed for hearing-impaired listeners; however, these listeners perform substantially better with dysarthric speech relative to speech in noise. The complex interplay between hearing loss and type of degradation will be discussed.
VR-based realistic assessment of annoyance for the noise of children running in apartment buildings
Authors: Jo Hyun In , Ahmed Shahzad , Kim Hyun Wook , Seo Chun Ki , Jeon Jin Yong
Published: October 2018

This study assessed annoyance response to temporal variations of sound energy of heavy floor impact in apartment buildings by using a virtual reality environment. As for a real moving sound source, the noise of a child running diagonally on the floor was reproduced by applying HRTF to the sound source of a single impact ball. Annoyance was assessed in the acoustic environment where visual information was provided by using HMD and directional information was given by using HRTF. A comparison scale using the equal-appearing interval (EQI) was adopted to reflect the sense of daily life. As a result, when visual information was provided in the VR environment, the annoyance of subjects decreased. On the other hand, directional information was given, the subjects became more sensitive to annoyance. Consequently, annoyance was more affected by the direction of a heavy moving sound source than the visual information. The VR-based environment of this study turned out to be realistic in a pyschoacoustic experiment.