bluuebunny/crossref_metadata_2025 huggingface dataset:
Ambient noise is “the new secondhand smoke.”
Authors: Fink Daniel
Published: November 2019

Ambient noise is “the new secondhand smoke.” Like secondhand smoke, excessive ambient noise is not just a nuisance but is a health and public health problem for millions of Americans. Excessive ambient noise causes hearing loss; disrupts sleep, function, and communication; and causes non-auditory health effects including cardiovascular disease and death. The sounds that matter to people are the ones reaching their tympanic membranes, or perhaps the cochlear hair cells or auditory processing cortex. Specific evidence-based noise exposure levels affect human health. 30 dBA (LAeq(8)) disrupts sleep. 45 dB (Ldn) disturbs concentration. 55 dB daily average (Lden) has non-auditory heath effects, including cardiovascular disease and death, due to stress responses including activation of the autonomic nervous system and neuroendocrine axis. Approximately 60 dBA (LAmax) interferes with speech comprehension for the hearing impaired. 70 dBA daily average (LAeq(24)) causes hearing loss, and 70 dBA (LAmax) interferes with speech comprehension for those with normal hearing. 85 dBA (LAeq(8)) is the occupational recommended exposure level in the United States, and 85 dBA (LAeq(1)) is the recommended exposure limit to prevent hearing loss. Acoustic scientists and engineers must be aware of these specific, evidence-based noise exposure levels and must work to reduce excessive ambient noise.
Reproduction of sound field dynamics by considering virtual acoustic impedance
Authors: Yokota Eiji , Katsura Seiichiro
Published: November 2019

Research on sound field reproduction mainly focuses on sound signal. However, the dynamics of a sound field needs to be taken into account when sound environment information (e.g., position of walls) in the original sound field changes. This paper proposes an acoustic control system that reproduces the dynamics of the original sound field by controlling the sound source that is a loudspeaker. Sound environment information is represented as virtual acoustic impedance, which is calculated with sound propagation models that regard a reflection surface as a mass-spring- damper system. The output of the control sound source is determined by recreating the virtual acoustic impedance of a specific position in the original sound field. This enables sound environment information of the original sound field to be reproduced in reconstructed sound fields. Therefore, the proposed method is able to deal with the situation where the dynamics of sound fields changes. Finally, to validate the proposed method, a one-dimension sound field with a rubber wall as the sound environment is reproduced using the proposed method.
Comparing soundscape assessment methods with natural-language expressions and a questionnaire survey: A case study in Seoul, Korea
Authors: Jeon Jin Yong , Jo Hyun In
Published: November 2019

A Swedish soundscape quality protocol was developed and has been used as a representative soundscape-quality assessment method around Europe. However, this protocol has limitations in Asian countries because the countries have distinctly different social and cultural backgrounds and form their own unique soundscapes. Consequently, this study examined the utility of a soundscape assessment survey for Koreans by comparing unconstrained natural-language expressions and existing protocol survey questions. To this end, soundscape data from a variety of places, e.g., parks, tourist attractions, and commercial areas in Seoul, Korea, were collected using 360-deg cameras and Soundfield microphones. In addition, a virtual-reality (VR) assessment environment was constructed using a head-mounted device (HMD) and 3-D audio technology under laboratory conditions, and the collected soundscapes were assessed. The participants were encouraged to freely and verbally express their thoughts about the sound environment of each place, and text data were obtained through voice-recognition technology. The protocol survey was conducted for the same subjects after the assessment. The results showed that it is necessary to develop a soundscape assessment standard that is appropriate for Koreans because differences from the existing European-style soundscape protocol were revealed in the assessment items, when an emotional analysis was conducted using text-mining technology.
Preschool[-aged] children's use of perceptual features to identify spoken languages
Authors: Mizrahi Reina , Creel Sarah
Published: November 2019

One major question in language development is when and how young language learners identify what language(s) they are hearing. Infants can discriminate languages when at least one is familiar. We have previously demonstrated that regardless of language background, 3- to 5-year-olds accurately associate two languages with two individuals (cartoons), but how they accomplish this is unclear. Here, we test whether bilingual (n = 32) and monolingual (n = 32) children associate perceptual features versus comprehensibility with individuals. During learning, children are familiarized with two cartoon characters: one speaks Spanish sentences; the other, English. At test, children see both characters and hear four trial types: English sentences; Spanish sentences; English-like nonsense; Spanish-like nonsense. Sense and nonsense sentences are acoustically matched via bidirectional cross-splicing. On each test trial, the child points to the character who they thought spoke, while eye-movements are being recorded. If children associate language-specific phonetic cues with talkers, they will choose English-speaking characters for English-like nonsense, and Spanish-speaking characters for Spanish-like nonsense. However, English monolinguals may associate characters with (non)comprehensibility. If so, they will choose the Spanish-speaking character for all nonsense utterances. Findings will reveal how much children use low-level perceptual features in language recognition, and whether this differs between bilinguals and monolinguals.
Geoacoustic inversion using vector acoustic modal dispersion
Authors: Bonnel Julien , Dall'Osto David R. , Dahl Peter H.
Published: November 2019

Geoacoustic inversion is traditionally performed using sound pressure data. Here, we present a study of geoacoustic inversion using particle velocity, as recorded on a vector sensor. The scope of the study is restricted to shallow water and low-frequency impulsive sources. In this context, the propagation is described by normal mode theory. The modal description of the vector field is well known: the mode amplitudes are different than from the pressure field, but their phase is the same. As a result, modes can be filtered from particle velocity data in the same way that they are filtered from pressure data, as long as one considers filtering methods that are based on the modal phase. We show that warping (a non-linear resampling scheme) enables modal filtering on both pressure and particle motion data. Then, the filtered modes (pressure and velocity) are coherently combined to form four vector acoustic metrics [Dahl and Dall’Osto, IEEE J. Oceanic Eng. 2019]. Each metric is used as an input for Bayesian geoacoustic inversion. The whole method is illustrated on a simulated scenario that reproduces the Seabed Characterization Experiment (SBCEX) that took place on the New England Mud Patch in 2017. [Work supported by the Office of Naval Research.]
Application of no-tachometer time synchronous averaging (TSA) and relative signal strengths to localize gear and bearing faults in a helicopter gearbox
Authors: Watson Dan , Reichard Dr. Karl
Published: November 2019

Health and Usage Monitoring Systems (HUMS) installed on helicopters monitor a wide variety of input signals to track system conditions. Improving fault detection on existing platforms precludes installation of additional hardware such as shaft speed sensors and additional accelerometers. The application of no-tachometer TSA and bearing fault harmonic energy techniques can be used to improve HUMS detection ability. In this presentation I will present a case study of gear tooth and bearing fault detection for a helicopter intermediate gearbox (IGB). Gear-mesh frequency demodulation is used to determine angular zero-crossing to synthesize a tachometer signal for gear fault detection, allowing for TSA techniques to readily identify gear tooth faults. The methods presented in "Autonomous Bearing Fault Diagnosis Method based on Envelope Spectrum" (2017 Klausen et al.) are then applied to determine the presence of bearing faults inside the IGB. Due to overlapping fault frequencies from multiple bearings a detected fault could be attributed to several bearings, the use of two accelerometer signals to spatially localize faults is developed and presented.
Target detection in pseudo Wigner-Ville distribution of underwater beamformed signals
Authors: Choo Yeon-Seong , Byun Sung-Hoon , Kim Sea-Moon , Lee Keunhwa
Published: November 2019

Because of clutter or reverberation in the water, it is difficult to distinguish a target from them with a beamforming image. It is well-known that the pseudo Wigner-Ville distribution, which is high-resolution time-frequency processing, can detect target signals effectively. In this study, the pseudo Wigner-Ville distribution with the beamformed signals was analyzed to detect an underwater target. The acoustic signals were measured using an array system consisting of a transmitting transducer and a line array of 16 elements at sea. The target was an air-filled aluminum spherical shell with a thin thickness. The transmitted signal was 3 to 8 kHz linear frequency modulation continuous waveforms. The experiment results show that the target can be easily identified with the pseudo Wigner-Ville distribution. [Work financially supported by the research project PES3180 funded by KRISO.]
Modeling sound propagation in the Great Salt Lake
Authors: Fronk Gabriel H. , Neilsen Tracianne B.
Published: November 2019

Acoustical waves can be monitored in a quiet underwater environment to identify noises, such as impacts and explosions. Our goal was to find the range of distance that acoustical sources can be detected in the Great Salt Lake. We measured the pressure from line explosives in the lake from varying distances to a triangle array of receivers. Various acoustical properties of the lake, like sound speed, density, and coefficient of attenuation, were then used in a range-independent propagation model to calculate transmission loss. Given the high salinity and shallow depth, the estimated transmission loss in the lake is large with this range-independent assumption. We found that in the best case scenario, there is a 60 dB re 1 μPa transmission loss at 3 km for most frequencies, which complicates source detection.
The Institute of Acoustics A B Wood Medal 2019: Julien Bonnel
Authors: Bonnel Julien
Published: November 2019

A common requirement in ocean acoustic applications is for robust signal processing algorithms that take into account the complex ocean environment, which is variable in space and time. Julien Bonnel's research has provided the most innovative approach to signal processing of broadband acoustic data in the last decade: time and frequency warping.

Warping is a non-linear signal re-sampling method, based on a physical model of the shallow water sound channel, which compensates for dispersion in the propagating modes. The technique extracts the propagating modes from broadband signals in shallow water at significantly shorter ranges than previously possible, using data from only a single hydrophone.

The technique he has developed has applications in two important areas: geo-acoustic inversion in shallow water environments and passive detection and localization of marine mammals. An example of the latter is the localization based on whale vocalizations, to enable estimation of the animal's depth in the water. The method has been successfully applied to obtaining the range and depth of bowhead whales in the Chuchki Sea and North Atlantic Right Whales in the Bay of Fundy.

Julien continues his research in geo-acoustic inversion to develop methods for extracting modal wavenumbers from short horizontal arrays. Of significant general interest is his work on re-formulating the modal filtering technique for sound channels with different dispersion characteristics.

Julien Bonnel is a most promising early-career research scientist who has introduced innovative methods that have led to significant advances in ocean acoustics. The research community has benefitted from the use of his methods and he has done this within a few years of completing his PhD. Importantly, he continues to produce innovative research to improve the methods that he has already developed.

The IOA is delighted to present Julien Bonnel with the 2019 A B Wood Medal.
A study of classroom acoustics: Verification of perception responses according to time-variant sound exposure
Authors: Engel Margret S. , Caniato Marco , Gasparella Andrea
Published: November 2019

In educational contexts, learning processes focus on stimulation and development of students’ cognitive abilities, which, in turn, will improve their learning capacity. Cognition refers to the mental activity of the process and uses information in judgment. Based on that, this study investigates how acoustic perception responses can differ according to sound exposure inside a classroom for different time spans. To achieve this aim, students and lecturers were asked to answer a survey about classroom comfort, which included acoustic perception questions, at a controlled environment classroom from the Free University Bozen-Bolzano. Perception responses could be given at any moment of the lecture, but it was recommended to answer the survey after the lecture. Additionally, two data collection campaigns were considered for this investigation: (1) without absorbers and (2) with fake absorbers. Sound pressure levels in octave bands were collected using a microphone array during the lectures period. The post-treatment of this data consisted of calculating sound pressure level averages for two different time spans: the whole lecture period and for the moment which the participants answered the survey. Room acoustic measurements were carried out to characterize the environment on different scenarios.
A deep convolutional neural network based classifier for passive acoustic monitoring of neotropical katydids
Authors: Madhusudhana Shyam Kumar , Symes Laurel B. , Klinck Holger
Published: November 2019

Insects occupy a central position in terrestrial trophic webs, consuming large amounts of vegetation and being consumed by other fauna. Changes in insect communities can have widespread effects across an ecosystem. In addition, having relatively small dispersal distances and stereotyped calls, insects make for an excellent choice as a monitoring target. Here, passive acoustic monitoring is employed for studying katydids, a relative of crickets and grasshoppers that are often charismatic mimics of leaves and sticks. In a prior study, call repertoires of over 60 species of katydids were established using individuals captured on Barro Colorado Island, Panama. These recordings are used in training a deep convolutional neural network based classifier, for subsequent analyses of long-term field recordings that are currently being collected. Coarse imbalances in the number of captured individuals per species and in their calling rates resulted in an unbalanced dataset. Furthermore, differences in recording equipment and in the recording practices posed challenges to achieving a well-rounded dataset. The measures taken to address these impediments will be discussed along with the classifier design choices. The classifier yielded >98% mean-average-precision over 60 classes on an exclusive validation split. Results of its application on field recordings will be presented.
Developing a click type “library” for Hawaiian odontocetes using machine learning methods
Authors: Ziegenhorn Morgan , Frasier Kaitlin E. , Oleson Erin M. , Keating Jennifer L. , Baumann-Pickering Simone
Published: November 2019

Though odontocete echolocation clicks are highly useful in passive acoustic monitoring, their acoustic features vary depending on behavior, orientation, and location relative to the receiver. Using unsupervised machine learning, regional sets of echolocation click types can be identified that allow for automated labeling of bioacoustic data while accounting for within-type signal variability. This methodology derives labels for clusters of click types based on parameters including spectral shape, inter-click interval, and click duration. Here we present classification results of echolocation clicks produced by Hawaiian odontocetes. Unsupervised methods were used to establish a set of click types for 10 years of recordings (200 kHz) collected from a bottom-mounted hydrophone off the coast of Kona, HI. These automated labels were compared with manual labels for species with established and recognizable clicks, which allowed for ground-truthing of some click types identified by the unsupervised machine learning method. Towed array data (500 kHz) was used to assign click types to species with visual verification, expanding the set of known species-specific click types for the region. The click types and method established here will be useful in future analyses of Hawaiian odontocete density estimation, abundance, and distribution patterns using acoustic data without requiring visual confirmation.
Philippine Sea observations of acoustic transmission phase and intensity fluctuations and comparisons to path-integral theory
Authors: Colosi John A. , Cornuelle Bruce , Dzieciuch Matthew , Worcester Peter F. , Chandrayadula Tarun K.
Published: November 2019

From April 2010 to March 2011, low frequency acoustic transmissions were carried out on a 330-km radius pentagonal acoustic array with a sixth transceiver in the middle in the Philippine Sea. Herein, we describe the fluctuation statistics of the signals originating on the six transceivers and recorded on a water column spanning receiver array located slightly off center of the pentagon. The signals analyzed here are interpretable in terms of specific acoustic ray paths clearly separable in time. Acoustic field statistics treated include (1) variances of phase and intensity, (2) vertical coherence and intensity covariance, (3) glinting and fade out rates, and (4) intensity probability density functions. Several of these observables are compared to predictions from Feynman path integral theory assuming the Garrett-Munk internal wave model suitably modified using Philippine Sea oceanographic observations. Data and theory differ by at most a factor of 2 and reveal the wave propagation regimes of unsaturated, and partially saturated.
Spatial and temporal correlations of mid-frequency acoustic signals on the Chukchi Sea Shelf
Authors: Turgut Altan , Collins Michael D. , Badiey Mohsen
Published: November 2019

The spatial and temporal correlations of 1.5–4 kHz LFM signals were measured using a 64-element billboard array and a mid-frequency acoustic source, deployed on the Chuckchi Sea Shelf during October 2016 to March 2017. The billboard array was deployed at 150 m water depth and the acoustic source was deployed at 320 m water depth near the shelf break to measure the acoustic signals propagating along a 20 km cross-shelf path. Both receiver depth (100 m) and source depth (200 m) were chosen to provide an effective transmission in a sound channel bounded by Pacific Summer Water at 40–100 m and warm Atlantic Water at 140-320 m below the surface. It was observed that signal amplitude variations and correlations were strongly affected by a combination of highly dynamic oceanography and Arctic sea ice. The effects of measured ocean and sea-ice variabilities were also simulated using a PE acoustic propagation model. The agreement between numerical predictions and measured data provides a framework for a robust mid-frequency sonar performance prediction capability in the Arctic. [Work supported by the ONR.]
Sonoprinting promotes drug delivery with liposome-loaded microbubbles and ultrasound
Authors: Versluis Michel , Lajoinie Guillaume , Roovers Silke , Deprez Joke , Lentacker Ine , De Smedt Stefaan
Published: November 2019

Ultrasound-triggered delivery from drug-loaded microbubbles has great potential due to its ability for localized release of the drugs while simultaneously enhancing delivery into the target tissue. We have recently proposed “sonoprinting” as a possible mechanism for the ultrasound-triggered delivery from nanoparticle-loaded microbubbles. It was shown that sonoprinting leads to the local deposition of nanoparticles and microbubble shell fragments in 2-D monolayer cultures. However, acoustic interactions between the bubbles and the rigid substrate could not be excluded. To verify whether sonoprinting can also occurs in more complex and physiologically more relevant tissues we study the US-triggered nanoparticle delivery from microbubbles to free-floating 3-D multicellular spheroids. Sonoprinting turned out to be a powerful tool to deliver large amounts of nanoparticles to the outer layers of tumor spheroids, followed by a complete drug release internalization into the deeper layers of the tumor spheroid. Sonoprinting significantly enhanced the cytotoxicity of both Doxil®-like and ThermoDOX®-like liposomes. We also provide evidence that only microbubble-associated nanoparticles become sonoprinted, while the uptake of free liposomal fraction is insignificant. As such, similar biological effects can be obtained through the use of substantially lower drug doses.
Non-invasive treatment of abscesses by histotripsy
Authors: Wang Yak-Nam , Brayman Andrew , Leotta Dan , Khokhlova Tatiana D. , Chan Keith , Monsky Wayne , Matula Thomas
Published: November 2019

Abscesses are infected walled-off liquid collections of pus and bacteria. They can affect any part of the body. Current treatment is typically limited to antibiotics, catheter drainage and hospitalization. Although bacteria can develop drug resistance, they are susceptible to mechanical damage from cavitation, as demonstrated in our prior in vitro work [Brayman et al., UMB 43, 1476–1485 (2017); Brayman et al., UMB 44, 1996–2008 (2018)]. Histotripsy is a pulsed focused ultrasound regime that generates localized cavitation and represents a potential new noninvasive treatment modality. Here, we present preliminary reports of inactivation of bacteria in a newly developed porcine abscess model. In this model, multiple large (2–4 cm) multiloculated bimicrobial abscesses can be formed at distinct sites in the same animal. The abscesses satisfy the true definition of an abscess and are formed within a relatively short period (2–4 weeks). The model was developed toward testing new abscess treatment technologies. We will describe the animal model, and preliminary results of histotripsy treatments in which liquefaction of the viscous pus contents and up to 5-fold reduction in bacteria viability were achieved. Funded in part by NIH NIBIB #R01EB019365 and R01GM122859.
Spectral moment measures for the analysis of acoustic swallowing evaluation
Authors: Chen Hsin-Hua , She Yunying , Lin Yaoh-shiang
Published: November 2019

During pharyngeal phase of swallowing, related muscles work together to produce wave-like contractions and to move food into esophageal phase. How the peristaltic contraction of muscles and movement of bolus coordinate can significantly strengthen or weaken one’s swallowing functions. This study uses the spectral moment analysis to investigate the acoustic effects of the peristaltic contraction wave during pharyngeal phase of swallowing. Four spectral moments describe features of the energy spectrum: the first moment (mean, centre of gravity) and the second moment (standard deviation) represent the spectrum's central tendency and dispersion respectively. Skewness and kurtosis (moment 3 and 4 ) represent spectrum's tilt and peak in relation to the central tendency. Results indicate that spectral moment measures may be one acoustic index sensitive to peristaltic contraction properties of swallowing. The statistical interpretation in accord with swallowing evaluation will be discussed.
Experimental extraction of loudspeaker parameters from sound transmission measurements in a plane wave tube for moving-coil drivers and passive radiators
Authors: Anderson Brian E. , Gregg Joshua F. , Young Sarah M. , Leishman Timothy W.
Published: November 2019

Moving-coil loudspeaker parameters are typically derived from electrical impedance measurements. Leishman and Anderson previously provided the theoretical foundations for extracting these parameters from sound transmission measurements conducted in a plane wave tube. This presentation will discuss experimental results of using this idea to extract the parameters of moving-coil drivers and those of passive radiators, the latter of which cannot be derived from electrical impedance measurements. The two-load method is used to account for the non-anechoic behavior of the tube to better enable accurate extraction of the sound transmission. Mechanical parameters are extracted from an open-circuit sound transmission measurement, and the electrical parameters are extracted by placing a wire across the loudspeaker’s terminals to provide a closed-circuit sound transmission measurement. Parameters extracted from measurements of electrical impedance, sound transmission, and destructive analysis of diaphragm assemblies will be compared.
Pyroelectric ultrasound sensor model
Authors: Kaupinmäki Santeri J. , Cox Ben , Arridge Simon , Baker Christian , Sinden David , Zeqiri Bajram
Published: November 2019

Ultrasound is typically measured using phase-sensitive piezoelectric sensors. Interest in phase-insensitive sensors has grown recently, with proposed applications in ultrasound attenuation tomography of the breast. The advantage of phase-insensitive imaging is that it does not suffer from degradation of image quality due to phase-aberration and narrow directional response. A numerical model of a phase-insensitive pyroelectric ultrasound sensor is presented. The model consists of three coupled components run in sequence: acoustic, thermal, and electrical. The acoustic simulation models the propagation and absorption of the incoming ultrasound wave. The negative divergence of the time-averaged acoustic intensity is used as a heat source in the thermal simulation for the time-evolution of temperature in the sensor. Both the acoustic and thermal simulations are performed using the k-Wave MATLAB toolbox with an assumption that shear waves are not supported in the medium. The final component of the model uses a pyroelectric circuit model which outputs the sensor response based on the temperature change in the sensor. The modelled pyroelectric sensor response and directional dependence are compared to empirical data. A physical model for the directionality of the sensor response is then proposed.
Large-eddy simulations of supersonic rectangular jets including screech
Authors: Wu Gary , Lele Sanjiva K. , Jeun Jinah
Published: November 2019

Large-eddy simulations (LES) are used to study supersonic jet screech, an aeroacoustic resonance phenomenon found in non-ideally expanded jets. This work specifically analyses screech generation for an under-expanded cold jet exhausted from a converging-diverging rectangular nozzle. With an aspect ratio of 4:1, the nozzle has a design Mach number of 1.44 and was previously tested at Florida State University. The simulations are performed with the compressible flow solver, “CharLES,” developed by Cascade Technologies. The meshes are generated based on the computation of Voronoi diagrams and contain around 40 to 120 × 106cells, targeting a few set points close to maximum screech. The far-field acoustics are obtained using a permeable Ffowcs Williams-Hawkings formulation in the frequency domain. In the noise spectra, screech tones are detected at various observer locations. At the specific tonal frequency, a spatially modulating standing wave pattern is observed in the near-field flow data, which possibly results from the partial interference between oppositely moving hydrodynamic and acoustic waves. Using the LES data, a modal form for the partial standing wave pattern can be obtained. Furthermore, a more in-depth stability analysis can provide insights on the origins and effects of these coherent features associated with screech.
Decomposition of the Navier-Stokes equations for noise source quantification within turbulent jets
Authors: Miller Steven A. , Patel Trushant K. , Shen Weiqi
Published: November 2019

Jet noise remains a community annoyance and a major source of hearing damage for military personnel. The physical and mathematical understanding of the noise source are critical for the purpose of its reduction. We decompose the flow-field into a base flow, large-scale spatially coherent structures, small-scale relatively incoherent structures, and associated radiated noise components. The large-scale and fine-scale structures are ascertained via an additional numerical decomposition approach. An acoustic analogy based model is used to predict the noise from the relatively small-scale incoherent turbulence and the large-scale coherent turbulence interacting with the shock-cell structure. We examine these source models combined with the decomposition of large-eddy simulation (LES). We show validated noise predictions of our LES solver with both the Ffowcs Williams and Hawkings equation and our newly developed jet noise model. We evaluate the source models obtained from the acoustic analogy, that are the two-point cross-correlations of the Navier-Stokes equations, to quantify all noise sources. The major advantage of the developed approach is the ease of quantifying both the shock-associated noise and the fine-scale mixing noise sources. Finally, we discuss how our model can be used with existing LES of turbulent flows for noise reduction.
Soft acoustic metamaterials: From broadband tunable metagels to directional emission
Authors: Fang Nicholas X. , Ma Chu , Li Xinhao
Published: November 2019

In this invited talk, we report the experimental investigation of hybrid meta-gel, a class of designed hydrogel composites with tunable acoustic properties over broadband frequencies. The meta-gel consists of patterned channels in a tough hydrogel matrix, where air, water, or liquid metal can be purged through the channels to tune the meta-gel’s acoustic transmission over broadband frequencies on demand. We show that the acoustic properties of the meta-gel can be tuned by varying the volume ratio of the channels, properties and ratio of the different filler materials with combined experiments, theory, and simulations. We validated that the hybrid metamaterial significantly increased directivity and main lobe energy over a broad bandwidth both numerically and experimentally. The meta-gel enables novel functions such as adjustable imaging regions of ultrasound, demonstrating tangible applications in underwater acoustics and medical imaging.
Wavefront shaping in underwater with soft gradient-index metasurfaces at ultrasonic frequencies
Authors: Jin Yabin , Kumar Raj , Poncelet Olivier , Mondain-Monval Olivier , Brunet Thomas
Published: November 2019

Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in the spatial wave response of these flat structures. Most of the recently reported acoustic metasurfaces were designed to control air-borne waves. Here, we report a new class of acoustic gradient-index (GRIN) metasurfaces engineered from soft graded-porous silicone rubber with a high and tunable acoustic index for broadband ultrasonic 3-D wavefront shaping in aqueous media. The functionalities of these soft flat lenses are illustrated through various experiments, which demonstrate beam steering and beam focusing, as well as vortex beam generation in free water. These new GRIN metasurfaces may have important applications in various domains using designed ultrasonic fields (biomedical imaging, industrial non-destructive testing, contactless particle manipulation), since their fabrication is very straightforward with common polymer science engineering. Y. Jin, R. Kumar, O. Poncelet, O. Mondain-Monval, and T. Brunet, Nat. Commun. 10, 143 (2019).
Anatomically realistic simulation framework for ultrasound localization microscopy
Authors: Belgharbi Hatim , Porée Jonathan , Damseh Rafat , Delafontaine-Martel Patrick , Lesage Frédéric , Provost Jean
Published: November 2019

Ultrasound Localization Microscopy (ULM) can map vessels at the capillary scale (<10 μm) by acquiring tens of thousands of images in which injected microbubbles are detected and tracked to generate super-resolved blood vessel maps. However, to our knowledge, there are no validation frameworks for ULM image formation algorithms. Herein, we developed a 3-D, anatomically realistic simulation tool based on serial two-photon microscopy (STPM). Rodent brain vasculature was segmented from STPM [1] into a graph-based model, which was then used to generate microbubble flow trajectories according to a velocity-diameter relationship derived from in vivo ULM data [2]. Ultrasound signals were obtained using a fast GPU-based simulator and reconstructed using our ULM image formation algorithm. We then proceeded to a parametric study. We first compared 2-D with 3-D imaging. Despite the latter's lower contrast, the gain in spatial information led to a more complete vasculature map. Localization precision was also enhanced since it was freed from the intrinsic localization error in the elevation direction. Also, increasing the number of transmits enhanced localization precision. From this study, we could establish a relationship between microbubble concentration and acquisition time for full network filling and optimal localization. This simulation tool provides thus a ground truth for the validation of ULM image formation algorithms and enables testing of new hypotheses. [1] R. Damseh et al., IEEE JBHI(2018). [2] V. Hingot et al., Sci Rep. (2019).
Teaching musical meter to school-age students through the Ski-Hill graph
Authors: Calilhanna Andrea
Published: November 2019

This thesis, Teaching Musical Meter to School-Age Students Through the Ski-Hill Graph, aims to demonstrate the “pedagogability” of modern meter theory, that is, that new scholarship on meter can translate into a coherent and practically implementable instructional curriculum, with various advantages for school-age students. The curriculum model developed in the thesis is derived from Richard Cohn’s work on and approaches to meter theory, the first comprehensive theory and approach to teaching and learning meter which focuses on the embodied psychoacoustic experience of sound and graphic representations of meter through mathematical music theory rather than notation-based understandings. The materials set out in the thesis demonstrate ways students might be taught to articulate their experience of meter. A unified approach, it incorporates Cohn’s ski-hill graph and other instruments of mathematical music theory such as the SkiHill app (Milne, 2018) and XronoBeat app (Milne, 2019) numbering for counting meter, cyclic graphs, and beat-class theory. The thesis demonstrates how traditional Western music theory has evolved due largely to non-Western influences to now possess the capacity for analyzing music from around the world. In addition, the outcomes it anticipates is a deeper engagement with music in classroom settings.
The role of listening effort during degraded speech recognition: A comparison of the dual-task and pupillometry paradigms
Authors: Colby Sarah , McMurray Bob
Published: November 2019

Listening effort is an increasingly important factor in understanding how people recognize speech in adverse conditions, especially for listeners with hearing impairment (Ohlenforst et al., 2017). However, the link between this basic construct and commonly used measures of listening effort is unclear. We compare two measures: dual-task performance and pupillometry, to investigate the relationship between different techniques for measuring effort and performance recognizing vocoded speech. In the dual-task experiment, participants (n = 26) completed a non-linguistic task (pattern matching) either with or without a concurrent speech task. The same participants completed a pupil task, which tracked changes in pupil size while participants recognized words. Both tasks used natural and noise-vocoded speech at two levels of degradation to vary participants’ ability to perform accurately. We found no relationship between dual-task performance and task-evoked changes in pupil size. However, the level of degradation uniquely predicted effort in the dual task, while accuracy uniquely predicted effort in the pupil task. This suggests that different measures of listening effort are sensitive to different underlying factors, including listening conditions and individual ability. Researchers should thus be aware of the sensitivities of a given task when measuring listening effort.
Perceptual evaluation of speech naturalness in speakers of varying gender identities
Authors: Merritt Brooke , Bent Tessa
Published: November 2019

Most auditory-perceptual evaluations of speech from individuals who are transgender have focused on perceived masculinity and femininity. Recent work has begun to investigate speech naturalness, which many transgender individuals report as a voice training goal. Voice masculinity/femininity may be linked to perceived speech naturalness based on listener sensitivity to talker gender and expectations surrounding prototypical male and female voices. Because transgender speakers are often rated as sounding less masculine or feminine than cisgender speakers, their perceived speech naturalness may be negatively impacted. This study investigates how speech naturalness ratings relate to masculinity-femininity ratings and gender identification (accuracy and reaction time). Spontaneous speech samples from 20 transgender (10 transmasculine; 10 transfeminine) and 20 cisgender (10 male; 10 female) speakers were included in three tasks: a two-alternative forced-choice gender identification task, a speech naturalness rating task, and a masculinity/femininity rating task. Utterances rated as less natural took longer to identify and were identified less accurately in the gender identification task; furthermore, they were placed in the middle of the masculinity/femininity scale. These results suggest that training to align a speaker's voice with their gender identity may concurrently improve perceptual speech naturalness.
Temporal cues from visual information benefit speech perception in noise
Authors: Yuan Yi , Lotto Andrew , Oh Yonghee
Published: November 2019

Speech perception in noise is a challenge for older adults and listeners with hearing loss. It is also challenging for a subset of listeners with normal hearing thresholds. One way to improve performance in noisy settings is to provide visual information of the talker. The current study examines what aspects of this visual input are necessary to receive an audio-visual benefit. To test the hypothesis that a visual analogue of the speech amplitude envelope aids speech comprehension, speech sentences in babble noises, with or without visual stimuli, were presented to listeners. In this case, the visual analogue was a sphere that varies based on normal, mismatched, and reversed relation to the amplitude envelope of the speech signal. Even when the audio-visual correlation is reversed (higher amplitude = smaller volumes), a significant improvement in speech perception in the auditory-visual condition versus the audio-only condition was gained even though no visual representation of phonetic information was available. These results provide strong evidence that the amplitude envelope can be inferred from visual displays and can be integrated online in speech perception. This study has implications for potential technological enhancements to speech perception with hearing devices – in particular, the integration of a non-auditory signal.
Two case studies of perceived age, perceived speech quality, and speech acoustics
Authors: Hunter Eric J. , Ferguson Sarah H. , Cantor Cutiva Lady Catherine
Published: November 2019

Physiological processes involving speech anatomical structures change with age and affect voice and speech production. Additionally, those with high voice demand (e.g., singers, teachers, coaches) have also demonstrated voice and speech production related changes. From a listener’s perspective, speech changes can be used to give insight into the vocal health and the age of a talker. This study compared perceived production quality, perceived age, and speech acoustics of two elderly individuals. Speech samples were used from two public figures. The first person (F, 78 y/old) gave an 8-h continuous public address. The second person (M, 49-98 y/old), spoke publicly for nearly 50 years. Using speech samples from both individuals, the following analysis were completed: (1) direct age estimation of samples; (2) production quality ratings trained listeners rated the samples voice quality using the GRBAS; and (3) acoustic analysis of the samples was performed. As would be expected, actual age and estimated age were related for the longitudinal samples representing 50 years of aging. Also, speech production quality and speech acoustic characteristics also changed with age. Interestingly, analyses of estimated vocal age was shown to decrease with prolonged vocal speaking showed a negative relationship (younger estimated age after hours of speaking).
Improving the dominant mode rejection beamformer with median filtering
Authors: Anchieta David C. , Buck John R.
Published: November 2019

Adaptive beamformers (ABFs) outperform conventional beamformers in detecting weak sources while attenuating background noise and strong interferers. Changing environments limit the number of snapshots that an ABF can average to estimate the sample covariance matrix (SCM). The dominant mode rejection (DMR) beamformer [Abraham and Owsley, Oceans (1990)] overcomes rank-deficient SCMs by imposing a structured covariance matrix which replaces the noise subspace eigenvalues by their average. However, the DMR beamformer often overestimates the dominant subspace dimension to avoid interferers contaminating the beamformer output. Overestimating the dominant subspace dimension introduces a bias to the background noise power estimate. This bias impairs the array gain and output signal to interferer and noise ratio (SINR). This talk proposes a modification to the DMR, replacing the average of the noise eigenvalues with an estimate of background noise power derived from the median of all eigenvalues. Simulations demonstrated that this new median-DMR beamformer improves the output SINR by up to 0.9dB compared to the standard DMR beamformer in scenarios which conservatively overestimated the dominant subspace dimension and suffered from a rank-deficient SCM. [Research supported by ONR 321US.]
Comparison of sonar systems for mapping of seaweed and infrastructure on macroalgae farms
Authors: Fischell Erin , Manganini Kevin , Whelan Sean , Kukulya Amy , Stanton Timothy K. , Lavery Andone C.
Published: November 2019

To increase production of seaweed to the point where it is economically viable as a biofuel, many developments are required in areas such as breeding and offshore farming systems. To inform decision making by farmers, maps of features that describe farm infrastructure, growth of seaweed, and fish populations are needed. As a part of the Advanced Research Projects Agency-Energy (ARPA-E) MARINER (Macroalgae Research Inspiring Novel Energy Resources) program, acoustic systems are being assessed for quantitative autonomous mapping. Multiple data collection sequences including various sonars and autonomous vehicles were used to better understand the efficacy of different sonars for this application. In data collection trials in New England sugar kelp farms using an autonomous surface vehicle, side-by-side sonar data were collected using a broadband split-beam sonar system, a low-cost 120 kHz narrow-band system, and a low-cost recreational fish finder. An autonomous underwater vehicle carrying a sidescan sonar system and broadband scientific split-beam sonar system was further used to collect data on both sugar kelp in New England and giant kelp in California. Measurements are compared for different mission objectives.
Acoustic source localization using drone-embedded microphone array
Authors: Guzik Mateusz , Kowalczyk Konrad , Woźniak Szymon , Fraś Mieszko , Juros Klara , Kaczor Daniel , Walas Piotr
Published: November 2019

High mobility and an ability of gathering data from large terrains makes Unmanned Aerial Vehicles (UAVs) an excellent platform for placing visual or acoustic sensors. One recently emerging application of UAVs is search and rescue operation, during which drones are used to localize people in distress. A common approach to determine the target position is to rely on visual data recorded by cameras. However, in situations of limited visibility such as in presence of smoke, at night or when a person is trapped under debris, acoustic information can be exploited to perform the localization of people in distress. Solutions based on acoustic information gathered by drone-embedded microphone array are a promising alternative to the methods based on vision, and they are currently being widely examined for UAV applications. The main issues encountered in acoustic source localization using drones include high ego-noise and wind produced by the propellers. This paper investigates the statistical properties of drone’s ego-noise and proposes an algorithm for acoustic source localization which exploits the sparsity of sound sources in time-frequency domain. A comparison of the results obtained by the proposed method and by commonly used approaches clearly shows the benefits of using the proposed processing.
Performance analysis of sparse and small arrays
Authors: Yang Tsih C.
Published: November 2019

Horizontal arrays are often used to detect/separate a weak signal and estimate its direction of arrival among many loud interfering sources and ambient noise. Conventional beamforming (CBF) is robust but suffers from fat beams and high level sidelobes. To improve performance, either high resolution beamforming is used, which has its own problems, or one needs to increase the array aperture, hence requiring more elements on the array. To reduce the cost, sparse and/or nested arrays have been proposed, such as the coprime arrays, to achieve approximately the same aperture, and hence the same beam resolution with a less number of elements. For sonar arrays, deconvolution is shown to yield an unique solution as opposed to, say, image processing. For coprime array, deconvolution algorithm is shown to yield a narrower beam width, lower sidelobe levels and higher array gain than the product or min processing, Deconvolution is shown to yield superdirectivity and supergain for a small array. This raises new research issues about optimal array configuration design.