bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of scattering and porosity on the apparent absorption in porous biphasic structures—Application to cortical bone
Authors: Karbalaeisadegh Yasamin , Yousefian Omid , Muller Marie M.
Published: October 2018

In this in-silico study, the attenuation coefficient in porous structures mimicking simplified cortical bone is calculated both in presence and absence of absorption, to isolate the effect of scattering on attenuation. Pore distributions with various pore concentrations (5–25 pore/mm2) and diameters (40–120 μm) are generated. The propagation of 8 MHz plane waves is simulated using a 2D FDTD package. The attenuation coefficient is measured by fitting the exponential decay of the signal amplitude in the frequency domain during propagation in the absence or presence of absorption (coefficient of 10 dB/cm/MHz to mimic bone tissue), for different pore concentrations and sizes. The difference between total attenuation and scattering attenuation coefficients (obtained with no absorption) is defined as the apparent absorption coefficient. For ka<1 (k: wave number; a: scatterer diameter) the effect of absorption does not change with increasing porosity. However, for ka>1, increasing porosity leads to a higher apparent absorption, indicating a higher impact of absorption, even though the absorption coefficient and the overall volume fraction of absorbing material (solid phase) were kept constant. This suggests complex interactions between the wave and the structure, and could be attributed to longer propagation paths in the solid phase due to multiple scattering by the pores.
Characterizing porosity in bone-like porous media from frequency dependent attenuation
Authors: White Rebekah , Yousefian Omid , Banks H. T. , Muller Marie M.
Published: October 2018

Osteoporosis affects both pore size and density in cortical bone. Quantifying levels of osteoporosis by inferring these micro-architectural properties from ultrasonic wave attenuation in cortical bone has yet to be done. Here, we propose a phenomenological power law model that captures the dynamics of frequency dependent attenuation in non-absorbing porous media mimicking a simplified cortical bone structure. We first demonstrate that, although it is frequency dependent, apparent absorption does not depend upon pore density and pore concentration, justifying the use of non-absorbing media for the simulations. We generate scattering attenuation data for various combinations of pore diameters (ranging from 20 to 100 μm) and pore densities (ranging from 3 to 10 pore/[mm]2) using a 2D FDTD package (Simsonic), which simulates the propagation of elastic waves at frequencies of 1–8 MHz. The model is then optimized to fit these datasets by solving an inverse problem under an ordinary least squares (OLS) framework. With this we establish linear, functional relationships between the optimized power law model parameters and the micro-architectural parameters. These relationships showed that ranges of porosity could be inferred from attenuation data. Applying these techniques to attenuation data from cortical bone samples could allow one to characterize the micro-architectural properties of bone porosity.
Benefits and challenges of using consumer audio equipment for unattended acoustical monitoring
Authors: Mennitt Daniel J. , Joyce Damon , Fristrup Kurt M.
Published: October 2018

The quality of an acoustical measurement impacts the accuracy of all inferences that rely on the resulting data. While standard sound level meters are well suited for noise studies requiring high precision, their cost, power consumption, and capabilities constrain the scope of application. Alternatively, the wide variety of consumer audio equipment offers many options for acoustical monitoring. The ability to make high resolution, multichannel audio recordings with packages that are relatively small, inexpensive, and low power is especially attractive for long-term acoustical monitoring in remote areas and large-scale spatial surveys that require many devices. These recordings are more valuable when they are calibrated and processed to yield sound level data. Despite the promise of consumer audio equipment, there are several drawbacks and unknowns. Within the framework of the signal chain, this talk will discuss some of the benefits, challenges, and unknowns of using consumer audio equipment for unattended acoustical monitoring.
Counting and tracking vehicles using acoustic vector sensors
Authors: Kotus Józef , Czyzewski Andrzej
Published: October 2018

A method is presented for counting vehicles and for determining their movement direction by means of acoustic vector sensor application. The assumptions of the method employing spatial distribution of sound intensity determined with the help of an integrated 3D intensity probe are discussed. The intensity probe developed by the authors was used for the experiments. The mode of operation of the algorithm is presented in conjunction with noise characteristics produced by moving vehicles. The optimization of the algorithm is based on measurements of intensity of sound emitted by the vehicle under controlled conditions. A test setup was built for this purpose with the use of measuring devices installed along a road with varying traffic flow. Reference data on the number of vehicles and traffic directions were prepared employing a recorded video and a reference traffic analyzer operating in lidar technology. It is shown that the developed acoustic method may contribute to an increase of effectiveness of commonly used vehicle counting systems employing inductive loops or Doppler radars. [Project financed by the by the Polish National Centre for Research and Development (NCBR) from the European Regional Development Fund under the Operational Programme Innovative Economy No. POIR.04.01.04-00-0089/16 “INZNAK—Intelligent road signs...”.]
Willis coupling in underwater elastic Helmholtz resonators
Authors: Su Xiaoshi , Norris Andrew
Published: October 2018

Helmholtz resonators (HRs) have been central in many acoustic metamaterial devices. For example, one can use an array of HRs to obtain negative effective bulk modulus or a panel of HRs to achieve total absorption of low-frequency sound. The aforementioned applications are based on the local monopolar resonance of each HR. However, the HR behaves differently in water. The elastic modulus of the resonator wall can become comparable to the modulus of water making the resonant frequency much lower than the rigid wall case. Moreover, considering the wall elasticity and mass leads to large structural asymmetry and induces cross-coupling between pressure and velocity fields. In this talk, we provide a lumped element model in order to predict the resonant frequency of the elastic HR. The model is demonstrated by sound scattering from an elastic HR in the context of acoustic bianisotropy, or Willis behavior, following a recent paper [Li Quan et al., Phys. Rev. Lett., 2018]. It is found that both the pressure and velocity fields can generate monopole and dipole responses from an elastic HR. The explicit example of an elastic HR in a one-dimensional waveguide will be discussed.
Dynamic homogenization of spatio-temporal metamaterials
Authors: Torrent Daniel
Published: October 2018

We discuss the homogenization of acoustic metamaterials with spatio-temporal modulation. It is shown that the effective medium required for the correct description of these structures is a non-recyprocal Willis material. Analytical expressions are given for the effective parameters, and several numerical examples are shown. The theory is applied as well to the specific case of thermal metamaterials, and it is shown that a thermal diode is feasible by spatio-temporal modulation.
Acoustic scattering by a Willis-coupled fluid cylinder
Authors: Amirkulova Feruza , Norris Andrew
Published: October 2018

We present an integral equation based approach to analyze an acoustic scattering from fluid cylinders exhibiting Willis coupling. The Willis-coupled cylinder is characterized by a bulk modulus and mass density as well as a coupling vector. The coupling vector relates the pressure and momentum density to the volume strain and particle velocity simultaneously. We consider integral representations obtained using the free-space Green's function for the exterior fluid medium. The integral equations are evaluated using the T-matrix method. The computation of scattered pressure wave due to an obliquely incident wave on bi-anisotropic fluid cylinder immersed in an external homogeneous fluid will be described. The method will be illustrated giving examples for fluid Willis cylinders.
Cochlear wave propagation under acoustical and electrical stimulations
Authors: Nankali Amir
Published: October 2018

Input sounds to the mammalian ear produce waves that travel from the base to the apex of the cochlea. These traveling waves stimulate the microstructure of the organ of Corti (OoC) in the center of the cochlea. The interplay between the traveling wave and a distinct nonlinear amplification process boosts the cochlear responses and enables sound processing over a broad frequency and intensity ranges. The in vivo electrical and acoustical stimulations have extensively been used to identify the underlying amplification process. In order to interpret the experimental data and propose a precise active mechanism, a comprehensive three-dimensional model of the cochlea is used. Our model predicts that applying an intracochlear excitation (electrical current or mechanical force) on a location along the cochlea generates a dispersive wave propagation in both forward and reverse directions. It is also found that the wave propagation in the cochlea is nonreciprocal when stimulated by an electrical current applied in the OoC. This effect is attributed to the feed-forward mechanism, mediated by a longitudinal electrical cable in our model. [This work was supported by NIH Grant Nos. DC-004084 and T32DC-00011.]
Alleviated cochlear damage in an inflammation suppressing model
Authors: Li Hongzhe , Sargsyan Liana , Hetrick Alisa
Published: October 2018

Cochlear inflammatory response to various environmental insults, has been increasingly become a topic of interest. As the immune response is associated with both pathology and protection, targeting specific components of the immune response is expected to dissect the relationships between cellular damage and inflammation-associated protection and repair in the cochlea. Duffy antigen receptor for chemokines (DARC) is a member of a group of atypical chemokine receptors, and essential for chemokine-regulated leukocyte/neutrophil trafficking during inflammation. Previous studies have reported that Darc deficiency alters chemokine bioavailability and leukocyte homeostasis, leading to significant anti-inflammatory effects in tissues following injury. In this study, we have used Darc knockout mice to determine the impact of a deficiency in this gene on cochlear development, as well as function in cochlea subjected to various stresses. We observed that DARC is not required for normal development of cochlear function, as evidenced by typical hearing sensitivity in juvenile Darc-KO mice, as compared to wild type C57BL/6 mice. However, Darc-KO mice exhibited improved hearing recovery after intense noise exposure when compared to wild-type. At cochlear locations above frequency range of the energy band of damaging noise, both hair cell survival and ribbon synapse density were improved in Darc deficient animals.
Behavioral methodology demonstrating the development of Tinnitus from chronic non-traumatic noise in mice
Authors: Burke Kali , Screven Laurel A. , Xu-Friedman Matthew A. , Dent Micheal L.
Published: October 2018

Tinnitus is the perception of a ringing or hissing noise in the absence of an external auditory stimulus. It can develop in one or both ears following acute or chronic noise exposure, head trauma, or as the result of natural aging. Using the Stolzberg et al. (2013, J. Neurosci. Methods) identification paradigm for rats, we assessed tinnitus in awake and behaving mice in response to long-term, non-traumatic noise exposure. Mice were trained to categorize three stimuli into two categories. Category 1 was 1/8 octave narrow band noise bursts centered around 4, 8, 16, 22.6, and 32 kHz. Category 2 was amplitude modulated white noise (modulated 100% at a rate of 5 kHz) and silent trials. Following this training period, mice lived in 85 dB noise for 23 hours a day and were tested for the remaining 1-hour each day. Most of the mice developed tinnitus, which was indicated by a shift in the categorization of the silence trials from category 2 to category 1. The present experiment demonstrates that chronic, non-traumatic noise exposure can induce tinnitus in mice in a similar way to salicylate injections in rats.
Acoustic features in speech for emergency perception
Authors: Kobayashi Maori , Hamada Yasuhiro , Akagi Masato
Published: October 2018

Previous studies have reported that the acoustic features such as the speech rate, fundamental frequency (F0), amplitude, and voice gender are related to emergency perception in speech. However, the most critical factor influencing the emergency perception in speech remains unknown. In this study, we compared influences of three acoustic features (speech rate, F0, and spectral sequence (amplitude)) to determine the acoustic feature that has the most influence on emergency perception in speech. Prior to conducting our experiments, we selected five speech phrases with different level of perceived emergency among various speech phrase spoken by TV casters during real emergencies. We then created synthesized voices by replacing three acoustic features separately among the selected five voices. In experiment 1, we presented these synthesized voices to 10 participants and asked them to evaluate levels of the perceived emergency of each voice by the magnitude estimation method. The results from experiment 1 showed that F0 was most influential on emergency perception. In experiment 2, we examined influences of the three acoustic features on auditory impression related to the perceived emergency by the SD method. The results suggested that emotional effects of some words such as “tense” or/and “rush” were influenced by the fundamental frequency.
Coordinated systems in Taiwan Mandarin tone production: An investigation of laryngeal and tongue movements
Authors: Chiu Chenhao
Published: October 2018

While electroglottography (EGG) is commonly used to examine different phonation types as well as laryngeal closure and opening of segments, only limited EGG studies focus on tonal quality [Brunelle et al., 2010, Phonetica, 67:147]. In particular, it is not yet clear how laryngeal movements in terms of its vibration magnitude and vertical displacement may be associated with pitch contour in tone production. The current study tackles this question by examining the amplitude of EGG pulses and laryngeal heights across four tones in Taiwan Mandarin. Ultrasound images are also obtained to assess the temporal relationship between tongue positioning and laryngeal movements during tone production. Preliminary results show that while the laryngeal area is more constricted by low, back vowels, a stronger correlation between EGG amplitude and pitch contour is found. On the other hand, when the tongue is positioned in the front of the cavity, larger degrees of freedom around the laryngeal area yield a lesser correlation between EGG amplitude and pitch contour but a stronger correlation between laryngeal height and pitch contour. The results suggest that tone production may be a result of a combination of laryngeal vibration and spatial coordination between the laryngeal and supralaryngeal movements. [Funding from MOST.]
Machine learning in detecting frequency-following responses
Authors: Hart Breanna , Jeng Fuh-Cherng
Published: October 2018

To improve the efficiency and timeliness in frequency-following response (FFR) testing, the purpose of this study was to investigate the capabilities of machine learning in the detection of an FFR. Continuous brain waves were recorded from 25 Chinese adults in response to a pre-recorded Mandarin monosyllable \yi2\ with a rising frequency contour. A total of 8000 artifact-free sweeps were recorded from each participant. Continuous brain waves accumulated (from the first sweep) up to the first 500 sweeps were considered FFR absent; brain waves accumulated (from the first sweep) up to the last 1000 sweeps (i.e., from 7001 to 8000 sweeps) were considered FFR present. Six response features (frequency error, slope error, tracking accuracy, spectral amplitude, pitch strength, and root-mean-square amplitude) were extracted from each recording and served as key predictors in the identification of a response. Twenty-three supervised machine-learning algorithms, with a 10-fold cross-validation procedure, were implemented via a Classification Learner App in MATLAB. Two algorithms yielded 100% efficiency (i.e., 100% sensitivity and 100% specificity) and 14 others produced efficiency ≥99%. Results indicated that a majority of the machine-learning algorithms provided efficient and accurate predictions in whether an FFR was present or absent in a recording.
Cyclic movement primitives underlying two-handed alternating signs in signed language
Authors: Tkachman Oksana , Purnomo Grace , Gick Bryan
Published: October 2018

Biomechanical constraints have been described as underlying patterns in speech production: e.g., cyclic neural central pattern generators (CPGs) in the jaw that evolved for chewing have been claimed to affect syllabic patterns [MacNeilage 1998, Behav. Brain Sci. 21: 4] and cyclic patterns in tongue tip movement may span sequences of segments [Derrick & al. 2015, JASA-EL 137:3]. Similarly, we propose that otherwise unexplained universal aspects of sign languages may result from a preference for repeated alternating arm movements developed in human ancestors for quadrupedal locomotion. For example, in ASL-LEX corpus of 1000 ASL signs, 159 are balanced (not including signs without movement or articulated in the transverse plane, which has alternative properties we will address in the talk). Of those, 60% are alternating, and the alternating group had fewer iconic signs (30.5% vs 41%) and more repeated signs (61% vs 30%) than symmetrical signs. While both groups had a large proportion of signs realized on coronal plane, which makes them more visible in face-to-face communication (33% for alternating vs 52% for symmetrical), the former have more signs in midsagittal and coronal/transverse planes (63% vs 44%), as predicted. Supporting data from additional sign languages will be presented.
The experience of music emotion in older adults with hearing loss and hearing aids
Authors: Russo Frank A. , Scholey Emma
Published: October 2018

The current study examined the effect of hearing loss and hearing aids in older adults on the experience of music emotion. Fifty-four participants aged 60 and above were recruited, including 18 with normal hearing (NH), 18 with hearing impairment (HI), and 18 with hearing impairment who use hearing aids (HA). Arousal ratings and skin conductance responses were obtained from participants across 24 extracts of film music that were previously validated as conveying one of four emotions: happy, sad, fearful, and tender. These four emotions represent a crossing of arousal (high and low) and valence (positive and negative). For each group, an “arousal range” was calculated as the average arousal ratings of happy and fearful excerpts, minus the average arousal ratings of tender and sad excerpts. A similar scheme was used for each group to determine a “skin conductance range”. For negatively-valenced music, groups did not differ with regard to arousal of skin conductance. For positively valenced music, NH and HA yielded a larger arousal range than did HI. A similar pattern emerged from the analysis of skin conductance range. Results will be discussed with regard to the acoustic cues to emotion in music and signal processing methods in hearing aids.
Decoding musical and vocal emotions
Authors: Paquette Sebastien
Published: October 2018

Many studies support the idea of common neural substrates for the perception of vocal and musical emotions. It is proposed that music, in order to make us perceive emotions, recruits the emotional circuits that evolved mainly for the processing of biologically important vocalizations (e.g., cries, screams). Although some studies have found great similarities between voice and music in terms of acoustic cues (emotional expression) and neural correlates (emotional processing), some studies reported differences specific to each medium. However, it is possible that the differences described may not be specific to the medium, but may instead be specific to the stimuli used (e.g., complexity, length). To understand how these vocal and musical emotions are perceived and how they can be affected by hearing impairments, we assessed recognition of the most basic forms of auditory emotion (musical/vocal bursts) through a series of studies in normal hearing individuals and in cochlear implant users. Multi-voxel pattern analyses of fMRI images provide evidence for a shared neural code for processing musical and vocal emotions. Correlational analyses of emotional ratings helped highlight the importance of timbral acoustic cues (brightness, energy, and roughness) common to voice and music for emotion perception in cochlear implant users.
Effects of benthic biology on geoacoustic properties of marine sediments
Authors: Lee Kevin M. , Ballard Megan S. , McNeese Andrew R. , Dorgan Kelly M. , Venegas Gabriel R. , Wilson Preston S.
Published: October 2018

Infauna dwell in the benthic zone and have the capacity to modify the physical and acoustic properties of the seabed through bioturbation. To investigate such effects, in situ measurements of compressional and shear wave speed and attenuation were conducted in Petit Bois Pass, near the mouth of Mobile Bay, Alabama, USA. The measurement system was deployed at multiple locations within the pass, and acoustic measurements were conducted at depths up to 20 cm into the sediment to scan the portion of the seabed where most infauna live. Additionally, diver cores were collected and analyzed for infauna abundance and geotechnical properties, such as porosity and grain size distribution, for comparison with the acoustic data. While sediment geoacoustic models do not explicitly account for effects of biology, they do allow for parameterization of various physical properties like porosity, grain size, or pore fluid viscosity, all of which can be modified by the presence of biological organisms and bioturbation. Results from the in situ acoustic measurements and core analysis will be compared with such models to determine if any additional insight into the acoustic effects of infauna can be gained. [Work supported by ONR and ARL:UT IR&D.]
Effects of benthic biology on normal-incidence reflection coefficient measurements
Authors: Isakson Marcia J. , Shearer Lucas
Published: October 2018

Normal-incidence reflection coefficient measurements have been shown to be sensitive to sediment type based on the structure and amplitude of the returned signal. In contrast to other sediment classification methods such as coring, these measurements can be done quickly and easily over a large area. This type of sediment classification scheme can also be integrated into surveys by single- and multi-beam echo sounders. However, benthic biology can substantially change the normal-incident acoustic return possibly confounding the sediment classification methods while simultaneously providing a method of assessing benthic eco-systems. In this study, a collection of normal-incidence measurements taken in a variety of underwater environments will be analyzed for the effects of benthic biology. The areas surveyed include the Chesapeake Bay, the Arctic, the Western Mediterranean, and Gulf Coast. Each of the datasets will be considered for the presence of benthic biology and its affect on geo-acoustic properties. [Work supported by ONR, Ocean Acoustics.]
Observations of the effects of benthic biology in measurements from the Acoustic Coring System collected in the New England Mud Patch
Authors: Ballard Megan S. , Lee Kevin M. , McNeese Andrew R. , Chaytor Jason D. , Reed Allen H. , Dorgan Kelly M. , Venegas Gabriel R. , Wilson Preston S.
Published: October 2018

This paper presents in situ measurements of sediment sound speed and attenuation collected in the New England Mud Patch using the Acoustic Coring System (ACS) with comparisons to sound speed measurements from a multi-sensor core logger (MSCL). The ACS uses rod-mounted piezoelectric cylinders mounted below the penetrating tip of a gravity corer to obtain a continuous record of sound speed as a function of depth as the corer penetrates the seabed. The MSCL measurements of the recovered sediment cores were acquired in 2 cm increments. In both the ASC and MSCL measurements, an elevated sound speed is observed in the upper 25 cm of the seabed which is the portion of the seabed where most infauna live. The sediments collected in the cores were analyzed for density, porosity, bulk organic matter, carbonate content, mineral composition, and grain size. Additional surficial sediment samples recovered using a box core and a multi-core were sieved for infauna collection. The organisms were preserved, identified, and classified according to acoustically relevant traits. The acoustic measurements are interpreted in terms of the physical measurements of cores and the abundance of different types of organisms present in the seabed. [Work supported by ONR.]
The mutual interface scattering cross section
Authors: Jackson Darrell , Tang Dajun
Published: October 2018

Scattering by the ocean surface or seafloor is often characterized by the interface scattering strength, the decibel equivalent of the scattering cross section per unit solid angle per unit area (referred to subsequently as the interface scattering cross section for brevity). The scattering cross section is a statistical second moment that allows modeling of the mean-square scattered pressure. Use of the interface scattering cross section requires that the incident field can be approximated by a single plane wave, a condition that is not satisfied when the interface is ensonified in the near field of a large array, as in synthetic-aperture sonar (SAS), or when multipath propagation is important as in modeling reverberation. The mutual cross section introduced in this presentation is a generalization of the interface scattering cross section to include ensonification by multiple plane waves. Examples of application to SAS and the ocean waveguide will be shown. In the latter case, it is seen that the mutual cross section can model peaks in the reverberation time series that occur as a result of multipath convergence on the interface. (Work supported by ONR.)
Autoproducts and out-of-band acoustic fields in refracting multipath environments with caustics
Authors: Worthmann Brian M. , Dowling David R.
Published: October 2018

Autoproducts are nonlinear mathematical constructions developed from a given acoustic field with non-zero bandwidth that can—with some limitations—mimic lower and higher frequency acoustic fields lying outside the bandwidth of the given acoustic field. The autoproducts’ mimicry of out-of-band fields is often sufficient for successful beamforming and/or source localization at below- or above-band frequencies chosen to correct array sparseness, suppress random scattering, mitigate environmental mismatch, and/or enhance resolution. While the limitations of autoproducts developed from acoustic fields well-described by ray acoustics are understood, what is less studied are the effects of diffraction and refraction. In this presentation, acoustic waveguide environments are defined which contain strong refraction, and form caustics—regions where nearby ray paths cross—which results in a phase shift in the propagating waves. These caustic phase shifts are not found in autoproduct fields and are detrimental for autoproduct-based remote sensing, especially in regions that are reached by multiple rays that have passed through different numbers of caustics. Multiple refracting environments are considered, including n2-linear and n2-quadratic sound speed profiles, and the ability of autoproducts to mimic out-of-band fields in these environments is assessed. Implications for autoproduct-based source localization are discussed. [Sponsored by ONR and NSF.]
Investigation of property losses in single crystal transduction devices
Authors: Warnock Michael , Howarth Thomas R.
Published: October 2018

With the advent of relaxor single crystal materials, such as lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) and lead magnesium niobate-lead titanate (PMN-PT), it was discovered that the highly oriented crystal structure of the materials leads to large values of dielectric and piezoelectric properties favorable to acoustic applications. When utilized in transduction devices, single crystal materials have demonstrated better acoustic performances compared to traditional designs. However, during construction of single crystal transducers, a capacitance loss is measured after mechanically bonding the crystal to a stiff backing material. The lower capacitance suggests a decrease in the effective permittivity, decreasing favorable piezoelectric constants for acoustic performance. In this study, the loss in effective permittivity was modeled using a commercial finite element analysis software. We present simulations used to demonstrate the loss in effective permittivity and compare with experimental measurements. Additionally, finite element simulations of several design considerations that can be utilized by transducer designers to minimize the loss in the effective permittivity are presented.
Soundscape characteristics in Southern Resident Killer Whale critical habitats
Authors: Vagle Svein , O'Neill Caitlin , Thornton Sheila , Yurk Harald
Published: October 2018

The Southern Resident Killer whales (Orcinus orca) (SRKW) are an endangered group of orcas with current range of Pacific North East from California to Northern British Columbia and spend most of the summer months in and around the Salish Sea. This group of mammals feed primarily on fish, are very local, and live in tight-knit family units called pods. July 1 2017 census reported 77 animals; which now has been reduced to 76 by a more recent death. Anthropogenic underwater noise, primarily from commercial and recreational vessels is suspected to have detrimental effects on these whales. Here, we present results from a seven month, continuous sound recording (125 kHz acoustic bandwidth), whale centered study to monitor and interpret different soundscapes in SRKW critical habitats. The six different locations studied have significantly different acoustic transmission characteristics and cover open ocean areas, where natural sound spectral levels are high, to areas where anthropogenic noise-sources dominate. Possible implications of these different characteristics on the ability of the orcas to communicate and find prey are discussed. [Work funded by the Ocean Protection Plan (OPP) of the Government of Canada.]
Grid-free compressive DOA estimation via alternating projection
Authors: Park Yongsung , Wagner Mark , Gerstoft Peter , Seong Woojae
Published: October 2018

On a discrete angular grid, the compressive sensing (CS) reconstruction degrades due to basis mismatch when the direction-of-arrivals(DOAs) do not coincide with the angular directions on the grid. To overcome this, we solve the DOA estimation in the grid-free angular domain. A method for solving the grid-free CS based beamforming problem is presented. The grid-free CS beamforming involves using a convex relaxation of a sparsity exploiting method and solving its semidefinite characterization. Current semi-definite programming solvers have high computational complexity for problems formed from typical large datasets. We solve the non-convex formulation of the grid-free CS beamforming optimization problem with alternating projections (AP). The AP based grid-free CS beamforming can solve large scale problems with hundreds of observations in a few seconds. We compare and contrast our algorithm with CS based beamforming as well as conventional beamforming.
Cross-stitched fabric as potential sound absorber for room acoustics applications
Authors: Tang Xiaoning , Yan Xiong
Published: October 2018

Textiles materials are widely used in noise and vibration control engineering. A thin fabric absorber consists of an air cavity and a backing rigid wall, and its main applications include ceiling, curtain, and sound barrier, etc. The main aim of this work is to study the acoustical and sound absorption properties of cross-stitched fabric, which has a similar structure with micro-perforated panel. The sound absorption coefficients of cross-stitched fabrics with different specifications were measured by impedance tube method, where the air cavity distance is 1 cm, 2 cm, and 3 cm, respectively. These distances are suitable to the binding and layout design of cross-stitched fabric painting in practical applications. As industrial textiles, cross-stitched fabric can be made into diversity of artistic patterns through manual or mechanized embroidery technology. This work has also studied the effects of multifarious embroidered patterns on the sound absorption coefficients of fabrics with different air cavity distance. In summary, cross-stitched fabric with exquisite patterns is expected to be a promising sound absorber for room acoustics.
Sound absorption through PDMS-based flexible perforated plate backed by a dual layer cavity
Authors: Kumar Sanjay , Bhushan Pulak , Bhattacharya Shantanu
Published: October 2018

A structure consisting of a perforated plate backed by an air cavity is a widely used structure for sound absorption in the low-to-high frequency range. In this study, we propose a sound absorbing metastructure composed of a polydimethylsiloxane (PDMS)-based flexible perforated plate backed by a layer of multiple hexagonal unit cells. Each unit cell consists of a dual cavity connected by a rigid perforated plate. The proposed structure allows for enhanced vibroacoustic coupling between the perforated plate and the back cavity. First, the structure is theoretically simulated using the finite element based analysis. The results elicit that the shape and size of the back cavity significantly alter the sound absorption coefficient and the resonant frequency of the structure. The geometrical parameters of the metastructure were further optimized using an artificial intelligence-based technique. Using the optimized geometrical parameters, the back cavity was printed using selective laser sintering (SLS) and a PDMS perforated plate has adhered on top of it. The experimental results demonstrate a potential sound absorption metastructure which can be utilized for multiple applications.
A diffuser language: Designing quadratic residue diffuser arrays with shape grammars
Authors: Dessi-Olive Jonathan , Hsu Timothy
Published: October 2018

This paper presents research on a rule-based approach to designing creative acoustic diffuser arrays. A shape grammar-influenced design method is specified that uses shape rules to recursively design arrays of quadratic residue diffusers (QRD) in a way that is neither mechanical nor deterministic. Shape grammar-based generative systems have already been shown to be capable of being used in architecture and engineering to create languages of functional objects but have not yet been extended into the realm of acoustics. The grammar presented by this paper produces a QRD-based acoustic diffusion language that breaks habits in QRD deploying techniques, which is lacking outside of using known equations that give known forms. The grammar can include different design frequencies and open the possibilities of different and non-uniform, intentional diffusion treatment. This paper will specify and demonstrate the formation rules, and discuss on how in combination with material specifications, this design method can generate broadband QRD arrays that address both performative and aesthetic criteria in new and surprising ways.
Acoustic impedance control for reproducing sound environment by constructing virtual wall
Authors: Yokota Eiji , Katsura Seiichiro
Published: October 2018

In order to obtain high presence, it is necessary to reproduce the sound environment of remote places. Conventionally, sound environments at remote places are reproduced by recreating a sound signal at that place. In this study, an acoustic technique that reproduces sound environments of remote places by recreating the dynamics of the environment at that place is proposed. In the proposed acoustic technique, the desired sound environment is attained by making listeners on the spot feel as if there were a wall that reflects and absorbs the sound waves. By controlling the acoustic impedance at the position where the wall is constructed, the wall is virtually built. In addition, the acoustic impedance including the virtual viscosity and elasticity that can be arbitrarily determined at the position where the wall constructed is set. As a result, by deciding the acoustic output from the secondary sound source so as to attain the desired acoustic impedance, the wall is virtually constructed to reproduce the desired sound environment.
Sound localization for estimating population densities of birds: Progress, challenges, and opportunities
Authors: Hedley Richard W. , Bayne Erin M.
Published: October 2018

Autonomous recording units (ARUs) are seeing rapid adoption as a research tool to estimate population densities of birds. One challenge for estimating population density is that the distance to the vocalizing bird is unknown. An emphasis has been placed on assessing the detection radius for different species on ARUs, and more recent work has had success relating sound amplitude to distance. We argue, however, that the true variable of interest is not density, per se, but the relationship between density and habitat type or other variables. In an ideal world, ARUs would collect information on the absolute location of each sound source, rather than the number of each species within earshot of the microphone, since the detection radius of an ARU commonly encompasses multiple habitat types. Sound localization is a promising solution to this problem, with some localization methods allowing sound sources to be pinpointed within 1m of their true location. We will present localization results comprising several thousand songs from several species in the Boreal forest, to highlight how localization data can be translated into estimates of population density. We will also highlight several challenges and opportunities for future contributions in the field of sound localization.
Detection probability of Cuvier’s beaked whale clicks from a glider and a deep-water float
Authors: Fregosi Selene , Harris Danielle , Mellinger David K. , Barlow Jay , Thomas Len , Klinck Holger
Published: October 2018

Work is being conducted to estimate marine mammal density and abundance from slow-moving, passive acoustically equipped underwater gliders and deep-water floats. We deployed five drifting acoustic spar buoy recorders (DASBRs) simultaneously with a seaglider and QUEphone float in the Catalina Basin of Southern California in 2016 to estimate the probability of detecting Cuvier’s beaked whale echolocation clicks from the glider and float. The DASBRs successfully localized and tracked individual whales, though a limited number of encounters prohibited estimation of detection probability through a trial-based method. We explored using a spatially explicit capture recapture (SECR) approach. The SECR analysis was modified to account for the non-static array and we explored sample size requirements for SECR using simulations. During tracked dives, over 200 one-minute time bins contained echolocation clicks on at least one DASBR. Of these, 10 and 34 bins contained clicks recorded on the glider and float, respectively, and were used to make preliminary estimates of detection probability as a function of range. Detection probability estimation is a key step towards animal density estimation; other information such as encounter rate and click production rates are required to estimate animal density, which will form the next part of this work.
Estimating densities of terrestrial wildlife using passive acoustic recordings: A pragmatic approach using paired human observations
Authors: Van Wilgenburg Steven , Sólymos Péter , Kardynal Kevin , Frey Matthew D.
Published: October 2018

The use of passive using acoustic monitoring is a rapidly growing field in terrestrial ecology, particularly in ornithology. Much recent work has focused on using recording technologies for large-scale occupancy monitoring, while local scale studies have focused on acoustic localization for density estimation. Density estimation offers numerous advantages for answering key conservation questions but may seem impractical to employ at national or continental scales using current acoustic localization techniques. Here, we describe how paired sampling can be used in conjunction with generalized linear (GLM) or generalized linear mixed models (GLMM) to estimate correction factors (δ) to derive density estimates from single acoustic recorders, provided that paired human observers conduct distance estimation. Thus, our approach provides an alternative to more complicated and expensive methods. We discuss the advantages and disadvantages of our approach and highlight the context in which we see various existing or emerging acoustic density estimation methods being used in the terrestrial environment, given the nature and scale of the ecological question(s) being asked.
Acoustic versus visual monitoring of Cetaceans in coastal habitats
Authors: Hendricks Benjamin T. , Keen Eric M. , Wray Janie L. , Alidina Hussein M. , Picard Chris R. , Meuter Hermann , Gulliver T. Aaron
Published: October 2018

Monitoring the aquatic soundscape provides critical information about marine mammal habitat use. It is essential for developing mitigation strategies for areas with expanding marine shipping and industrial activity. A long baseline hydrophone array has been installed in Squally Channel, a culturally, ecologically, and economically important marine environment in northern British Columbia, Canada. The array consists of four synchronized bottom-mounted hydrophones that permanently record and radio-transmit data to a land-based laboratory in real-time. The acoustic monitoring is supplemented with a land-based visual observatory that oversees the same area of approximately 200 km2. Automated detectors have been developed for vocalizations of humpback whales, orcas, and fin whales. Acoustic data and visual surveys were analyzed for a period of more than 100 days between 2017 and 2018. We present an overview of the acoustic detection functions and their performance by call type and summarize visual survey procedures. Cetacean activity derived from automated acoustic detections and visual observations is analyzed. Finally, acoustic and visual survey methods are compared to assess a) the fraction to which different species are acoustically active while in the area, and b) the effectiveness of both acoustic and visual monitoring efforts for the purpose of cetacean monitoring.
In vivo ultrasonic evaluation of distal part of radius in their early teens
Authors: Matsukawa Mami , Mano Isao , Horii Kaoru , Umemura Shiori , Ozaki Etsuko
Published: October 2018

For the evaluation of small radius of early teens, we have improved the ultrasonic bone measurement system, LD-100 (OYO electric)1, which can evaluate the distal 5.5 % site of the radius of the non-dominant hand. The system measures two longitudinal waves (fast and slow waves) which propagate in the inside cancellous bone. We can also obtain the spatial distribution of wave attenuation during propagation in bone, which can be presented as an attenuation map. In our present teen’s bone evaluation project (ages 12-18, n = 971), we found an open epiphysis at the distal end of radius in some attenuation maps of early teens. The area seems to be the growth plate, which have the ability to lengthen the bone by creating new cartilage within the bone itself. In case of boys, the plates were found at the age of 14 or less. The values of body weights and heights of the teens with the growth plates were smaller than the average, telling that they are growing up. These results show the possibility of growth evaluation using ultrasound techniques. 1. H. Sai, et al., Osteoporos Int. (2010) 21:1781–1790.
Seismo-acoustic detection and tracking of small aircrafts
Authors: Bhattacharyya Joydeep , Reiff Christian G. , Sim Leng , Alberts W. C. Kirkpatrick
Published: October 2018

The Army Research Laboratory is undertaking an investigation to combine acoustic and seismic vector sensors, in conjunction with traditional acoustic arrays which use omnidirectional microphones, to detect and track small airplanes. The focus of this study is to improve the fidelity of the track with a sparse network and explore its applicability in both urban and rural settings. Towards this end, we carry out a field test where multiple aircrafts with known flightpaths are acoustically and seismically monitored over a period of several days. Using a detection algorithm that leverages both the blade frequency of the propellers and the Doppler associated with near-source propagation, we demonstrate that both acoustic and seismic data have the ability to detect and track the aircrafts. Both acoustic and seismic vector sensors have the ability to estimate both the arrival time and the azimuth to the source which lead to smaller sensor footprint. By combining multimodal sensing with novel target tracking techniques, we can reduce the impact of clutter while maintaining a robustness of our detection and tracking algorithms. A comparison of the acoustic and seismic vector sensors in tracking small aircrafts will be discussed.
Estimation of the source distance using the multiple three-dimensional acoustic intensimetry
Authors: Jung In-Jee , Ih Jeong-Guon
Published: October 2018

A 3D acoustic intensimetry (AI) in tetrahedral configuration can be used for the source localization. Such a 3D AI module is compact, but it can also yield a precise bearing angle for the low Helmholtz numbers if some bias errors are compensated. In this study, besides the bearing angle, the source distance is estimated by using the multiple 3D AI probes with different acoustic centers. Because each AI module indicates a vector from the acoustic center to the source direction, the nearest point between any pair of line vectors can approximate the source position. The source position can be estimated by minimizing the least square error of the positions determined by multiple intensity vectors. Such idea is preliminarily tested with four 3D AI modules, of which each module is composed of 4 MEMS microphones separated by 30 mm. Four 3D AI modules are also arranged in a tetrahedron layout, and the source frequency range is 0.5–2 kHz. The distance between modules is varied for 150–250 mm range, and the source distance for 1–4 m range. Current test results reveal that the estimation error is less than about 2, 5, and 7% when the elevation angle is within 0–30°, 30–60°, 60–90°, respectively.