bluuebunny/crossref_metadata_2025 huggingface dataset:
Absorption and dispersion of low-frequency sound waves in the main cloud layers of Venus
Authors: Trahan Adam , Petculescu Andi
Published: April 2018

We present predictions for the acoustic wavenumbers at low frequencies in the condensational cloud layers of Venus, occurring between 50 and 70 km, approximately. While the general thermodynamics of Earth clouds is well understood, that of Venusian clouds is still a matter of debate. Venus' clouds are formed primarily of H2O and H2SO4 vapors and aqueous sulfuric acid droplets, the fluxes of which are not fully constrained due to the few insitu observations. This study is based on and adapted from the terrestrial model of Baudoin et al. (J. Acoust. Soc. Am. 130, 1142 (2011)). Inside the clouds, the Navier-Stokes equations of continuum fluid mechanics are used for the gaseous (dry + vapor) and liquid phases of H2O and H2SO4, combined with the equations describing the evaporation/condensation processes; the gaseous phase is treated as an ideal gas. Outside the clouds, in the CO2—dominated atmosphere, the van der Waals equation of state is used. [The work was supported by a Grant from the Louisiana Space Consortium (LaSPACE).]
Effect of clustered bubbly liquids on linear-wave propagation
Authors: Fan Yuzhe , Li Haisen , Xu Chao , Chen Baowei
Published: April 2018

The spatial distribution of bubble liquids strongly affect linear-wave propagation in bubbly liquids. The classical understanding suggests that using positional correlations of the bubbles, such as “hole correction” or Perkus-Yevick approximation, describes the spatial information of bubble clouds. However, bubbly liquids are observed experimentally with complex bubble ensembles that take the form of clusters, filaments, and clouds which cannot be intuitively described by these pair-correlation functions and need to be better clarified. To achieve this purpose, a three-dimensional random model, the Neyman-Scott point process, is proposed to describe bubbly liquids with clustering. Base on this method, we study the influence of such phenomenon on acoustic dispersion and attenuation relations. A formula for effective wavenumber in bubbly liquids is derived, based on self-consistent method. Comparing with the equation of Commander and Prosperetti [J. Acoust. Soc. Am. 85, 732 (1989)], our results show that the clustering can suppress peaks in the attenuation and the phase velocity as functions of the frequency. Further, we provide a numerical simulated method. A clustered bubbly liquid is simulated with strict mathematical method and the statistical informations are obtained through unbiased statistical approach. Through the results, we quantificationally analyze the influence of estimated value on predictions.
A model of the neuronal processing of interaural time disparities
Authors: Encke Jörg , Völk Florian , Hemmert Werner
Published: April 2018

The auditory system of humans and other mammals is able to use interaural time and intensity differences as well as spectral cues to localize sound sources. One important cue for localizing low-frequency sound sources in the horizontal plane are interaural time differences (ITDs), which are first analyzed in the medial superior olive (MSO) in the brainstem. Results from electrophysiological and psychoacoustic studies suggest ITD encoding in the relative activities of neuronal populations in the two brain hemispheres. This contribution first explores the neuronal encoding of fine-structure ITDs using a physiologically motivated spiking neuronal-network model of the mammalian MSO. Results from this model confirm robust ITD encoding in the relative activity of the MSOs in both hemispheres. Based on the neuronal-network simulations, a simple probabilistic model of subsequent ITD processing is proposed. This simplified model connects the neuronal responses of the two hemispheres with different hearing sensation properties, such as lateral position, spatial extent, or number of spatially separable sensations. First predictions from the model are discussed with regard to the results of a series of psychoacoustic experiments on the lateralization of pure-tone impulses presented via headphones.
Evidence for the origin of the binaural interaction components of the auditory brainstem response
Authors: Tolnai Sandra , Klump Georg
Published: April 2018

The binaural interaction component (BIC) is discussed as a potential tool to objectively measure listeners’ binaural auditory processing abilities. It is obtained from auditory brainstem responses (ABRs) by subtracting the sum of the ABRs to monaural left and monaural right stimulation from the ABR recorded under binaural stimulation. The sources of the BIC, however, have not yet been agreed upon. Candidate source regions are the lateral and medial superior olives (LSO and MSO, respectively) in the superior olivary complex where excitatory and inhibitory inputs converge. Our study aims at identifying the source of the BIC. Simultaneously to ABRs, we recorded local-field potentials (LFPs) and single-unit (SU) responses from the LSO and MSO of ketamine/xylazine-anaesthetised Mongolian gerbils and derived LFP-related and SU-related BICs the same way as ABR-related BIC. We then compared the properties of LFP-related and SU-related BICs with the ABR-related BICs. LFP-related BICs recorded in the LSO did not mirror the characteristics of the ABR-related BIC while the SU-related BIC did. In the MSO, neither LFP-related nor SU-related BIC mirrored ABR-related BICs. This suggests that the output of LSO units but not MSO units contribute substantially to the generation of the ABR-related BIC.
Is there a relationship between perceptual difficulties and auditory functioning at the periphery and the brainstem in children suspected with auditory processing disorder?
Authors: Boothalingam Sriram , Veeranna Sangamanatha , Allan Chris , Purcell David , Allen Prudence
Published: April 2018

The test battery typically used for the diagnosis of auditory processing disorder (APD) is highly heterogeneous, with an emphasis on the central auditory nervous system. As such, the peripheral auditory system is typically only screened for the presence of an overt hearing loss. Our previous work suggested that children suspected of APD (sAPD) have atypically sharp cochlear tuning when measured using stimulus frequency otoacoustic emission (SFOAE) group delay. In the present work, we extend our previous findings and test the hypothesis that cochlear tuning influences auditory brainstem response (ABR) latencies. Our hypothesis is based on filter theory, which suggests that a sharper filter will take longer to build-up and ring longer. We predicted that sharper cochlear filters in sAPD should result in delayed ABR wave latencies and will be associated with poorer performance on speech perception tests. Preliminary data from 16 sAPD and 6 typically developing children show a positive correlation between cochlear tuning and ABR peak I latency. Cochlear tuning explains a significant proportion of the variance in ABR peak I latency (R2 = 0.25). Further behavioral results and implications for inclusion of auditory peripheral examination in APD tests will be discussed.
Dynamic allocation of listening effort when listening to speech
Authors: Winn Matthew
Published: April 2018

Measuring listening effort is an essential part of understanding the communication ability of a person with hearing loss. In this study, we are using pupillometry to measure how listener effort changes over the course of an utterance, in cases where the listener has reason to allocate effort earlier or later in time. Listeners completed a sentence-recognition task where high- or low-context sentences were followed by various stimuli (noise/digit sequences/speech) or silence. In cases where listeners can “restore” misperceived words with the aid of context, we see significant late-occurring reductions in pupil size when a sentence is followed by silence. This alleviation of cognitive activity is shown to be systematically disrupted by sounds (noise or speech) that are played after the end of the sentence. Furthermore, we show evidence of reallocation of effort earlier in time in cases where that disruption is expected. This underscores a largely underappreciated challenge in auditory perception, which is not limited to the coding stimulus itself, but also planning and post-stimulus processing. This phenomenon might underlie individuals’ difficulty in real-life scenarios where a single mistake cannot be corrected in time, and cascades forward to disrupt perception of later utterances.
Using functional near-infrared spectroscopy to assess auditory attention
Authors: Zhang Min , Ihlefeld Antje
Published: April 2018

Speech intelligibility in background sound can improve when listeners attend to the target. Using functional magnetic resonance imaging, previous work demonstrates that auditory attention alters Blood Oxygenation Level Dependent (BOLD) signals in the lateral frontal cortex (LFCx; Michalka et al., Neuron 2015), at least when directed to spatial cues. Using functional near-infrared spectroscopy (fNIRS), we recorded BOLD responses from LFCx in 54 normal-hearing participants, each performing one of three auditory experiments. The weights of general linear modeling (GLM) fits of the fNIRS recordings were compared using analysis of variance. In experiment 1, when listeners selectively attended to stimuli differing in pitch and space, both left and right LFCx showed significant activation (p = 0.01 and 0.02 for left versus right LFCx). In contrast, passive listening to speech-shaped noise did not cause significant changes in LFCx activation (p = 0.3 and p 0.1 for left versus right LFCx). Experiment 2 confirmed these results, revealing comparable fNIRS traces when attending to pitch alone, versus attending to space and pitch. Experiment 3 further strengthened these results by controlling for eye movements. Result suggests that fNIRS is a viable tool for assessing whether or not a listener deploys auditory attention to perform a task.
Cortical mechanisms underlying perception in complex auditory scenes
Authors: Shamma Shihab
Published: April 2018

Humans and many animals can easily attend to one of multiple similar sounds, segregate it, and follow it selectively over time even in extremely noisy environments. I shall review the psychological and neural underpinnings of this perceptual feat, explaining how it fundamentally depends on the representation of sound in the auditory cortex. I shall then outline how the attributes of simultaneous sounds (pitch, timbre, and location) are disentangled into separate streams, and bound into unified sources, by the temporal coherence of the cortical responses they evoke and their rapid adaptive properties. Recent neurophysiological results in support of these ideas will be discussed, especially in animals that have been trained to segregate and attend to the speech stream of a target speaker in a mixture. Finally, these findings will be related to analogous tasks in other sensory systems (visual object segregation in crowded scenes), leading to biologically inspired computational algorithms that may perform these tasks with no prior information or training.
Jim Jenkins—Mentor extraordinaire
Authors: Kuhl Patricia K.
Published: April 2018

James J. Jenkins (J3 to his students) was the quintessential mentor. As a graduate student at the University of Minnesota in the late 1960s in Speech Communication, Jim was a member of my advisory committee, and a strong advocate of my interests and pursuits in the area of language and the brain. Jim set up a research fellowship for me with Dr. Hildred Schuell, a clinical scientist he deeply respected and collaborated with on publications, who was Director of the Aphasia Section in the Neurology Service at the VA Hospital in Minneapolis. I began to study the effects of cerebrovascular accident (stroke) on language, and was thrilled to be there. Unfortunately, Dr. Schuell succumbed after a sudden onset of cancer 9 months after my fellowship began. I remember asking Jim, “now what?” J3’s reply, and the 3-month assignment he gave me, changed my life, setting me on a course that I remain on to this day. I was never able to thank J3 enough for his sage advice. Jim’s talent at mentoring students—his ability to understand where they might shine—is something that inspires me every day.
Recent findings on children’s lexical tone development: Implications for models of speech development
Authors: Wong Puisan
Published: April 2018

Lexical tone is important for a majority of the world’s languages. Prior research consistently reported that children mastered lexical tone production between 1;6 to 2;6 of age, supporting the prevailing notion of theories of speech acquisition that children acquire supra-segmental features early and rapidly before mastering the full set of segmental features. However, intriguingly, studies that examined children’s Cantonese tone perception found that children failed to accurately identify Cantonese tones in monosyllabic words until after eight years old, five years after children’s full mastery of tone production at three years old, which questioned early acquisition of supra-segmental features and the widely accepted assumption in speech acquisition models that speech perception precedes speech production. Wong, Schwartz, and Jenkins (2005) started a series of studies using a new paradigm that controlled lexical expectation in tone rating to examine lexical tone development in children and reported strikingly different results. Monosyllabic and disyllabic tones produced by five and six years old Mandarin-speaking children growing up in the U.S. and in Taiwan and Cantonese-speaking children growing up in Hong Kong were not adult-like. Tone production development was slower than tone perception development. The findings shed new light on universal models and theories of speech acquisition.
“If a perceptual problem exists, what are its roots?” Types of cross-language similarity, hypercorrection, and unexplored root canals
Authors: Bohn Ocke-Schwen , Ellegaard Anne A. , Garibaldi Camila L.
Published: April 2018

James Jenkins had a keen interest in the nature of perceptual problems of nonnative listeners and in the perceived similarity of speech sounds. This presentation reports on a series of experiments which examined how well four different types of similarity predict nonnative speech perception. The different types are ecphoric and perceptual cross-language similarity, perceived within-language similarity, and acoustic similarity. One set of experiments examined how well cross-language perceptual assimilation (English to Danish) and within- language similarity ratings (English-English) of English consonants by Danish listeners predict Danes’ identification of English consonants. Another set of experiments explored the roots of English listeners’ discrimination problems for the closely spaced Danish unrounded front vowels by relating these problems to two types of perceived cross-language similarity (ecphoric and perceptual) and to acoustic similarity. Results suggest that each of the four types of similarity accounts for some of the perceptual problems, but none does so exhaustively, probably because the root system of these problems is affected by additional factors including nonnative listeners’ hypercorrection and by perceptual asymmetries. The clear conclusion from these experiments is that Jim’s question will keep us busy for quite some time. [Work supported by Carlsberg Foundation and Inge Lehmanns Legat af 1983.]
Tracking the time course of individuals' perception and production of coarticulated speech
Authors: Beddor Patrice S.
Published: April 2018

Pioneering research by James J. Jenkins and colleagues has demonstrated the importance for speech perception of the dynamic information specified across the syllable. Collaborative work in our lab builds on this tradition of studying listeners' use of dynamic information by investigating perception of coarticulatory information as it unfolds in real time. We are currently studying listener-specific strategies for attending to coarticulatory dynamics, and are asking whether these strategies are linked to that individual's own production patterns. I will report the results of experiments that test the hypothesis that individuals who attend to coarticulatory information especially closely in perception also produce more consistent and extensive coarticulation. The perceptual measure is the time course of participants' use of coarticulated vowel nasality in CVNC words as measured via eye tracking; the production measure is the time course of these participants' nasal airflow while producing CVNC words. Results support our hypothesis: participants who produced earlier onset of coarticulatory nasalization were, as listeners, more efficient users of that information as it became available to them. Thus, a listener's use of the dynamics of speech is predicted, to some degree, by that individual's production patterns. [Work supported by NSF grant BCS-1348150.]
Sampling with semi-coprime arrays
Authors: Adhikari Kaushallya
Published: April 2018

This research introduces a new array geometry called Semi-Coprime Array (SCA) that has the potential to significantly increase the degrees of freedom of a Uniform Linear Array (ULA). An SCA interleaves three ULAs (Subarray 1, Subarray 2, and Subarray 3). Each SCA has two underlying coprime integers (M and N). Subarray 1 and Subarray 2 have undersampling factors based on the coprime integers M and N, while Subarray 3 is a full ULA with the number of sensors determined by the undersampling factors of Subarray 1 and Subarray 2. Interleaving the three subarrays results in a highly sparse non-uniform linear array. Taking the minimum of the three subarrays' outputs produces a pattern that is devoid of aliasing, yet offers the resolution of a full ULA with equal aperture. An SCA offers closed form expressions for sensor locations which many existing sparse arrays do not. Compared to other existing sparse arrays that offer closed form expressions for sensor locations, coprime arrays and nested arrays, an SCA saves more sensors and matches the peak side lobe height of a full ULA with less extension.
Effects of lag redundancy on array beam patterns and redundancy patterns for extended co-prime arrays
Authors: Pyzdek Andrew T. , Swanson David C.
Published: April 2018

Lag redundancy describes the number of times a given spatial lag is measured by an array. For sparse arrays, the reduction of lag redundancies is generally desirable for lowering cost and processing overhead. However, as lag redundancies determine the natural weighting function of an array’s spectral estimates, the pattern of redundancies dictates the natural beam pattern of a given array. We consider the impact of array sparsity on sidelobe level and array gain in both weighted and unweighted conventional beamforming. This analysis is then applied to co-prime arrays, for which redundancy patterns can be determined based solely on the choice of array length and co-prime factors. It is also shown that the spatial positions of lag redundancies are semi-regular, a desirable feature for sampling some complex environments.
Frequency-difference wavenumber analysis with a sparse array
Authors: Kim Donghyeon , Choi Yonghwa , Cho Seongil , byun gihoon , kim Jea Soo
Published: April 2018

Frequency (f)- wavenumber (k) analysis can be used to estimate the direction of arrival (DOA) [J. Acoust. Soc. Am. 69, 732–737 (1980)]. When the receiver is a sparse array that is not suitable for conventional plane-wave beamforming, it adversely causes aliasing error due to spatial sampling, thus many striation patterns can emerge in f-k domain. In this study, we propose frequency-difference wavenumber analysis that is motivated frequency-difference beamforming [J. Acoust. Soc. Am. 132, 3018–3029 (2012)]. It is found that this approach can mitigate (or eliminate) such aliasing effect, which extends its applicability to the robust DOA estimation. Numerical simulation and experimental results are presented, and a major drawback is discussed.
Numerical determination of Green's functions for far field scattering solutions
Authors: Gunderson Aaron M. , Isakson Marcia J.
Published: April 2018

Typical finite element target scattering results are evaluated over a small physical domain and then propagated to the far field using the Helmholtz-Kirchhoff integral. This process allows for direct far field data-model comparison and is substantially faster than evaluation over a large domain. It does, however, require knowledge of the Green’s function of the target’s environment. For underwater buried targets, the two-medium Green’s function pertaining to the water and sediment is often not readily known and can be cumbersome to analytically solve or approximate, particularly when surface roughness or volume inhomogeneity is to be incorporated. Instead, the Green’s function can be determined directly through numerical methods. A direct process for numerical Green’s function determination in an arbitrary two-medium environment is proposed, and is used to determine the far field scattering from buried targets. Results are compared to experimental scattering records on buried elastic targets, and to other models where the Green’s function was determined/approximated analytically. [Work supported by Applied Research Laboratories IR&D and ONR, Ocean Acoustics.]
Separation of multiple backscattered echoes using dictionary updating sparse method
Authors: Meng Xiangxia , Li Xiukun , Jakobsson Andreas
Published: April 2018

Sparse signal representation method has been proven to be effective to estimate and separate the multiple backscattered echoes from underwater target. Usually, the transmitted signal is used as a template to generate the dictionary. It is efficient under assumptions that the knowledge of signal components is perfectly known, or the deviations from the dictionary can be ignored. However, the properties of the echoes differ from the clean reference signal because of the scattering mechanism. In contrast, it has necessity to extract these deviations to have deep insight of the target. Herein, we propose a sparse method that allows the dictionary to be updated. The initial dictionary is defined as a usual way, i.e., based on the transmitted signal. Then, we use a constrained optimization problem to generate dictionary that differs from the original one, introducing an updating procedure. We introduce two constraints, one is to penalize the updated dictionary to be sparse and the other one is to ensure the elements do not deviate too much from the original dictionary. In this way, the resulting dictionary can be used to reconstruct the backscattered echoes, which is illustrated to be efficient with high accuracy by simulated and experimental results.
Coherent fusion of multi-aspect scans of UXO targets from CLUTTEREX16
Authors: Marston Timothy
Published: April 2018

During the ONR and SERDP sponsored 2016 CLUTTEREX experiments, a large number of UXO were placed in a target field. These UXO were scanned by a sonar system mounted on a linear rail. Following each scan, the UXO were rotated in place by increments of 20 degrees to build up a multi-aspect acoustic characterization of each target. An automated process was subsequently developed to coherently fuse the results of these rotations to form 180-degree wide acoustic characterizations that could be used to represent the target in the complex image, frequency vs. aspect, or time vs. aspect domains. This talk will discuss the fusion process and the results for UXO and clutter objects in the target field.
Elastic features in time-frequency representations for target classification
Authors: Arrieta Rodolfo , Malphurs David E. , Paustian Iris , Lim Raymond
Published: April 2018

Time-frequency representations aid in the interpretation of backscattered chirps, allowing a physical basis for selection of features for target classification using machine learning approaches. However, trade-offs in resolution, computational efficiency, noise reduction, and cross term rejection are made in these 2-D representations. Since our goal is the isolation of physically-meaningful features that will aid in the classification of targets, we are mainly concerned with the ability of these representations to reject noise. Towards this end, we have developed synthetic signals designed to robustly enhance the energy in the elastic portion of the acoustic backscattered return; thus, increasing the SNR for difficult targets. Previously, we demonstrated a capability to class-separate a diverse group of targets using features derived from time-frequency representations of signals collected at high SNR target aspects. In recent work this capability is being extended to other target aspects where SNR is weak by using our synthetic signals. This is demonstrated with cylindrical targets, where physics-based target models helped select the most robust elastic modes to use in the design of these synthetic signals. Results based on data collected from underwater unexploded ordnance and simple cylindrical targets will be presented. [This work was sponsored by SERDP and NSWC PCD.]
Utilization of aspect angle information in synthetic aperture images
Authors: Plotnick Daniel , Marston Timothy
Published: April 2018

Synthetic aperture sonar (SAS) involves the creation of high resolution images of a scene via scattered signals recorded at different locations. Each pixel of the reconstructed image includes information obtained from multiple aspects due to the changing position of the sources/receivers. The aspect dependent scattering at each pixel may be exploited to provide additional information about the scene; we will present a framework for converting and utilizing multi-aspect data, as well as several examples. This aspect dependency may be leveraged to separate objects of interest from the background, to understand the local bathymetry, or for visualizing acoustic shadowing in circular aperture sonar (CSAS) images. Additionally, the aspect dependence of low-frequency elastic scattering from objects may be used to understand underlying scattering physics; a laboratory example is presented.
Laboratory simulation of backscattering by a hemisphere in a boundary wave-guide with an external source
Authors: Fortuner Auberry R. , Marston Philip L.
Published: April 2018

While there have been various investigations of backscattering when a source and a target are situated in the same wave-guide, the situation when the source is external to the wave-guide is less well explored. For example, a target buried in a mud layer over sand [K. L. Williams, J. Acoust. Soc. Am. 140, EL504 (2016)], the mud layer may act as a wave-guide. The target signatures when the source is in the water column above the mud are modified. A laboratory experiment has been performed to isolate wave-guide effects on target backscattering, using a simplified wave-guide in water. The wave-guide is defined between a free water surface and a thin partially transparent acrylic plate placed below the water surface. A soft spherical target is half-exposed at the free-surface and source-receiver is below the plate. A geometric method-of-images model gives the timing arrivals of wave-guide echoes from an infinite number of back-scattering paths that undergo multiple reflections in the wave-guide and gives the frequency response of the wave-guide by summation of the contributions. This model gives a closed-form result in the far-field limit, and is compared to the experimental results in the time and frequency domains. [Work supported by ONR.]
Architectural acoustics continuing education course—Presenter registration and reporting requirements
Authors: Brooks Bennett M.
Published: April 2018

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects called “Architectural Acoustics,” for which attendees can earn one continuing education unit (CEU). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork so that AIA members may receive credit for the course. The manner in which the course is given is also dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course. Of course, anyone is free to register with the AIA to provide their own CEU program. However, the advantages of participating in this program are that the TCAA short course is already prepared, it is pre-approved by the AIA, and the registration fees are paid by the Acoustical Society of America.
Stay tuned: Active processes tune tree cricket ears to maintain a match to temperature-dependent song frequency
Authors: Mhatre Natasha , Pollack Gerald , Mason Andrew
Published: April 2018

Tree cricket males produce tonal songs, which are used to attract mates and to interact with other males. In other crickets, the mechanical properties of their peripheral auditory system have evolved to have resonant modes at the communication frequency. The tree cricket auditory system, however, is not passively tuned to song frequency. Tree crickets exploit an active amplification process to tune hearing to song frequency. However, their song frequency increases with temperature, presenting a problem for tuned listeners. We show here that the actively amplified frequency increases with temperature, and shifts mechanical and neuronal auditory tuning to maintain a match with changing song frequency. We also find that in tree crickets active amplification does not provide greater sensitivity or dynamic range than that observed in other crickets that lack active amplification. Thus, the primary adaptive function of active amplification is to ensure that auditory tuning remains matched to conspecific song frequency, despite changing environmental conditions and signal characteristics.
A neural circuit for song pattern recognition in the cricket brain
Authors: Hedwig Berthold , Schoeneich Stefan , Kostarakos Konstantinos
Published: April 2018

Acoustic communication is based on amplitude and frequency modulation of sound signals. Temporal features of the signal require processing by central auditory neurons, the brain circuits, however that detect temporal features are poorly understood. We show how five neurons in the brain of female field crickets form an auditory feature-detector circuit for the pulse pattern of the male calling song, and exhibit properties of a delay-line and coincidence-detection mechanism. The network receives its direct input from a single ascending auditory interneuron. An internal delay that matches the pulse period of the calling song is established by a non-spiking brain neuron. In response to a sound pulse, it generates a transient inhibition that triggers a delayed rebound depolarization. The direct input and the delayed responses converge in a coincidence detector neuron, which responds best to the pulse pattern of the species-specific calling song as the rebound activation of the non-spiking neuron coincides with the response of the ascending interneuron to the subsequent sound pulse. The output of the coincidence detector neuron is further processed by a feature detector neuron to suppress unselective responses and background activity. The circuit reveals principal mechanisms of sensory processing underlying the perception of temporal auditory patterns.
Making high-stakes decisions in complex acoustic environments: Revisiting the Cocktail Party problem in a multimodal sensory context
Authors: Howard Daniel R. , Lee Norman , Hall Carrie L.
Published: April 2018

Ambient noise in its many forms represents an ecological reality and evolutionary driver that influences numerous expressions of animal behavior, especially those associated with communication. Noise often extends across sensory modalities, resulting in channel-specific effects that can range from non-additive to synergistic. Here, we describe how noise modality influences female preference for a preferred signal trait (low dominant frequency) in the lek-mating prairie mole cricket, Gryllotalpa major, a species whose mating system has evolved in the ecological context of both biotic and abiotic noise. We conducted two-choice playback experiments with females presented with male signals of the preferred vs. non-preferred trait in the context of isomodal (male chorus), cross-modal (substrate-borne vibration) and multimodal noise (both) conditions. We found that female preference for lower DF signals was robust to isomodal noise, but preference was weakened in treatments with a cross-modal stimulus only. Female performance in multimodal noise was comparable to control and isomodal treatments, suggesting that while cues obtained via the subgenual organs can mask salient airborne information, biotic noise may act as a releaser from this interference.
An objective metric for describing the basic acoustics of binaural directivity patterns in humans
Authors: Dittberner Andrew , Ma Changxue , de Vries Rob
Published: April 2018

It is accepted knowledge that having two ears are better than one when trying to listen to a signal of interest in the presence of spatially-separated noise sources (e.g. Blauert, 1997; Bregman, 1994; Zurek, 1993). Models have been proposed purporting of the benefits of the head shadow effect, binaural interactions, and cognitive factors that explain how one can understand sound with linguistic or other contextual meaning better in the presence of spatially-separate noise sources. However, less discussed is the attribute of human listeners having the ability to also hear and identify sound sources, seemingly on demand, that occur around them, a condition made possible by the fact of having two ears. Zurek (1993) proposed and discussed at length on the directivity effects of binaural listening (e.g., Better Ear Strategy). What is proposed in this study is an extension to this model to include the omni-directional directivity effects of binaural listening to describe the listener’s ability to remain connected and aware of the sound landscape that surrounds them. Where the head shadow effect plays a role in improving the signal-to-noise ratio in one of the two ears, this strategy looks at how the two ears, due to their geometric location on the head, allows for the head to be acoustically transparent and keeps the listener connected to their surrounding sound landscape.
Model-based Bayesian signal processing in acoustics
Authors: Xiang Ning
Published: April 2018

Bayesian signal processing has been increasingly applied to a wide variety of acoustical research and engineering tasks. Bayesian probability theory provides acousticians with an elegant framework for inferential data analysis which facilitates learning from acoustic experimental investigations that provide an improved understanding of the underlying theory. In these inferential analysis tasks, certain prior knowledge is often available about the acoustical phenomena under investigation, based either on the underlying physical theory or on certain phenomenological relationships. Bayesian probability theory allows this available information to be incorporated in the processing and analysis and exploited in the Bayesian framework as physical or phenomenological models. Many analysis tasks in acoustics often include two levels of inference, the model selection and the parameter estimation. Bayesian signal processing provides solutions to these two levels of inference by extensively using Bayes’ theorem within this unified framework. This talk will discuss various model-based approaches recently applied to signal processing and analysis in acoustics using either one or both levels of inference.
Ultrasound measurements in the work environment
Authors: Radosz Jan , Pleban Dariusz
Published: April 2018

For the frequency range above 20 kHz, there is no clear and complete information on the factors influencing the result of a measurement of sound pressure level. Moreover, there are no current international standards for performing measurements of ultrasound at work stations. The authors presents a possibility for the adaptation of the existing measurement methods, in particular, the requirements for measuring instruments, procedures to be followed while performing measurements, the application of a correction to measurement results, and the determination of measurement uncertainty. The development of a consistent method of ultrasound measurement is of utmost importance in carrying out an assessment and reducing the risk of exposure to this physical factor in the work environment.
A scavenger hunt using ultrasonic geocaches
Authors: Dolder Craig N.
Published: April 2018

Sound is commonly used for either communication or navigation. An ultrasonic scavenger hunt was designed that does both and is designed to raise awareness about acoustics. This scavenger hunts utilizes ultrasonic geocaches to both give information to the participants and educate them on topics including, the fact that sound may not be audible, the concept of hearing loss, other animals hear at different frequencies, and general facts from the hosting event. The geocaches use the frequency band above typical human hearing but still within the bandwidth of most personal electronics, 20 kHz–22 kHz. This band can be picked up by common smartphones and tablets and viewed using free spectrogram applications. The maximum sound pressure level output by the geocache devices falls below maximum public exposure recommendations but the signal is still visible on a spectrogram. The scavenger hunt was trialed at a science engagement event at the University of Southampton with over 6000 in attendance.
Activity in human auditory cortex represents spatial separation between concurrent sounds
Authors: Shiell Martha , Hausfeld Lars , Formisano Elia
Published: April 2018

Auditory spatial information can enhance stream segregation in an auditory scene, but little is known about how auditory space is represented in the human cortex. If spatial cues are used for scene analysis, then it is the distance between sounds rather than their absolute positions that is essential, and thus, we hypothesized that auditory cortical neurons encode separation between sounds rather than absolute location. To test this hypothesis, we measured human brain activity in response to spatially-separated concurrent sounds with magnetic resonance imaging at 7 Tesla. Stimuli were spatialized amplitude-modulated broadband noises, recorded for each participant via in-ear microphones prior to scanning. Using a linear support vector machine classifier, we investigated if sound location and/or spatial separation between sounds could be decoded from the activity in Heschl's gyrus and the planum temporale. The classifier was successful only when comparing patterns associated with the conditions that had the largest difference in perceptual spatial separation, and not in conditions where only location changed and separation remained constant. Our pattern of results suggest that the representation of separation is not merely the combination of single locations, but is an independent feature of the auditory scene.
Applications of the hybrid finite element method
Authors: Vlahopoulos Nickolas , Lee Sungmin
Published: April 2018

The hybrid finite element analysis (Hybrid FEA) method is based on combining conventional finite element analysis (FEA) with energy finite element analysis (EFEA) for expediting the FEA computations when very dense models are needed. The difficulty in using conventional FEA at higher frequencies originates from requiring a very large number of elements in order to capture the flexible wavelength of the panel members which are present in a structure. In the Hybrid FEA the conventional FEA model is modified by de-activating the bending behavior of the flexible panels in the FEA computations and introducing instead a large number of dynamic impedance elements for representing the omitted bending behavior. The excitation is considered to be applied on the conventional FEA model and the vibration analysis is conducted. The power flow through the dynamic impedance elements is computed and applied as excitation to the EFEA model of the flexible panels. The EFEA analysis computes the vibration of the flexible panels. In the past, the Hybrid FEA has been utilized successfully for evaluating the vibration is production automotive and rotorcraft structures. A brief theoretical background will be reviewed, the practical aspects of the method will be discussed, and results from previous correlation studies will be presented.
A symmetrical formulation of coupled BEM/FEM for submerged structures based on acoustical reciprocity
Authors: Chen Pei-Tai
Published: April 2018

The paper presents a structural acoustics formulation for elastic structures submerged in water. The structural equation is described by a finite element method where the linear displacement variables on the wetted surface are chosen locally as one normal displacement and the other two displacements tangent to the wetted surface, whereas the rest of rotational displacements or degrees of freedom not contacting with water are defined globally. A boundary element formulation describing the acoustic loading on the structure is expressed as a function of normal velocity or displacement on the wetted surface. The coupling of the FEM and BEM is through the normal velocity, or equivalently, the normal displacement on the wetted surface. An acoustical reciprocity is used to prove that the associated acoustic loading expressed as the normal displacement of the wetted structure is a complex symmetric matrix. This matrix can be viewed an acoustic element whose degrees of freedom are the normal displacements of the wetted surface. Thus, the coupled FEM and BEM becomes a symmetric banded matrix formulation, leading to an efficient numerical way to solve the equation. A capped cylindrical shell with periodical ring stiffeners and bulkheads submerged in water is used to demonstrate the present numerical method.
Finite element computation of the scattering response of objects buried in ocean sediments
Authors: Bonomo Anthony L. , Isakson Marcia J.
Published: April 2018

To assist in locating objects at or near the ocean floor, there is a need for computational models that can predict the scattering response of objects fully or partially buried in ocean sediments such as sand. In reality, sand can best be understood as a two-phase porous medium and the shear waves supported by the sediment can contribute meaningfully to the acoustic signature of the buried objects. Due to the slow phase speeds of these shear waves, the computational burden of finite element models can be excessive. In this talk, efficient modeling techniques and methods for reducing the computational time of these models are covered. [Work supported by ONR, Ocean Acoustics.]
A procedure for ship identification through acoustic signal processing
Authors: Too Gee-Pinn J.
Published: April 2018

All ship’s mechanical structures are different. Hence, the radiated noise spectra are different, especially in line spectra. Line spectra are composed of the spectra due to shaft speed and structure resonance. It is appropriate to identify ship by line spectra. In this study, a ship noise model has been used by combining line spectrum and continuous spectrum of a ship. Then, artificial neural network (ANN) has been used to calculate the contents of the line spectrum of a ship noise in order to identify a ship. Furthermore, in order to identify ship correctly, the received signal is restored to the source signal. Before signal restoration, the source needs to be located. Hence the signal restoration and source localization are the important issues for ship identifications. Finally, adaptive time reversal (ATR) is used to locate source and to restore signal. The results indicate that ATR is effective in source localization and source signal restoration. Therefore, it shows great advantages in identifying a ship
Extraction of independent non-Gaussian components from non-Gaussian background
Authors: Koldovský Zbyněk
Published: April 2018

Independent component analysis (ICA) is a popular method for Blind Signal Separation applied to multichannel linear recordings. Convolutive mixtures of acoustic signals can be separated by applying ICA in the frequency domain to each sub-band separately or jointly as in Independent Vector Analysis (IVA). However, this way, the mixtures are separated into that many components as is the number of sensors. ICA and IVA are therefore not effective in applications where only one (or few) signals are of practical interest. We introduce a new parameterization of the ICA mixing model that is optimized for the extraction of one signal of interest (SOI). The approach is called Independent Component Extraction (ICE) and is closely related to methods for Blind Signal Extraction (BSE) such as One-unit FastICA. However, BSE methods assume that background signals (the other signals than SOI) are all Gaussian, which limits their accuracy. In this work, we show that ICE can be extended also for a non-Gaussian background so that the accuracy of algorithms is improved, although all components are not separated as in ICA. We also introduce an extension for the extraction of a vector component, so-called Independent Vector Extraction.
UTDallas-PLTL:Advancing multi-stream speech processing for interaction assessment in peer-led team learning
Authors: Hansen John H. L. , Dubey Harishchandra , Sangwan Abhijeet , Kaushik Lakshmish , Kothapally Vinay
Published: April 2018

Robust speech processing for single-stream audio data has achieved significant progress in the last decade. However, multi-stream speech processing poses new challenges not present in single-stream data. The peer-led team learning (PLTL) is a teaching paradigm popular among US universities for undergraduate education in STEM courses. In collaboration with UTDallas Student Success Center, we collected CRSS-PLTL and CRSS-PLTL-II corpora for assessment of speech communications in PLTL sessions. Both corpora consist of longitudinal recordings of five teams studying undergraduate Chemistry and Calculus courses consisting of 300 hours of speech data. The multi-stream audio data has unique challenges: (i) time-synchronization; (ii) multi-stream speech processing for speech activity detection, speaker diarization and linking, speech recognition, and (iii) behavioral informatics. We used a 1 kHz tone at the start and end of each session for time-synchronization of multi-stream audio. We leveraged auto-encoder neural network for combining MFCC features from multiple streams into compact bottleneck features. After diarization, each speaker segment is analyzed for behavioral metrics such as (i) dominance; (ii) curiosity in terms of question inflections; (iii) speech rate; (iv) cohesion; and (v) turn-duration and turn-taking patterns. Results are presented on individual and team based conversational interactions. This research suggests new emerging opportunities for wearable speech systems in education research.