bluuebunny/crossref_metadata_2025 huggingface dataset:
A modal collocation algorithm for high-frequency propagation in discontinuous waveguides
Authors: Ginsberg Jerry H.
Published: April 2018

A procedure for analyzing high-frequency propagation in adjoining constant width waveguides was presented previously [Ginsberg, JASA 134, 4217 (2013)]. The parallel walls were taken to be rigid, and no results were provided. This presentation uses that development as the foundation for the analysis of waveguides having an arbitrary number of sections, each of whose walls have arbitrary local impedance. The analytical basis is description of the pressure field in terms of transverse pressure modes, each of which is associated with upstream and downstream propagation at wavenumbers that may be complex, depending on the wall properties. Pressure and particle velocity conditions at junctions of two segments are enforced exactly by collocation along the common cross section. Initiating the procedure at a passive termination leads to recursion relations for modal reflection and transmission coefficients at each junction, which are independent of the nature of the excitation. Satisfaction of the conditions at the end that is excited leads to another algorithm for all modal amplitudes. An example is used to compare the convergence properties of the collocation method to an analysis based on the orthogonality of the transverse modes.
Human dissimilarity ratings of musical instrument timbre: A computational meta-analysis
Authors: Thoret Etienne , Caramiaux Baptiste , Depalle Philippe , McAdams Stephen
Published: April 2018

Musical instrument timbre has been intensively investigated through dissimilarity rating tasks. It is now well known that audio descriptors such as attack time and spectral centroid, among others, account well for the dimensions of the timbre spaces underlying these dissimilarity ratings. Nevertheless, it remains very difficult to reproduce these perceptual judgments from distances computed on acoustical representations such as the waveform or the spectrogram. Interestingly, biologically inspired representations based on spectrotemporal modulation spectra such as spectrotemporal receptive fields (STRF) have been shown to be well-suited to reproduce human dissimilarity ratings (Patil et al., 2012). Here, we propose a meta-analysis of seven former studies on timbre spaces in light of these recently developed representations. We implemented a computational framework that optimizes the correlation between the perceptual results and distances obtained from a set of different acoustic representations, in particular through the STRF. We observed that distances computed from spectrotemporal modulation representations provide the best correlation with the perceptual results across the seven timbre spaces. Finally, we highlighted the parts of the representations contributing the most to the correlation suggesting new insights into the underlying perceptual metrics. [Supported by Canada Research Chair, NSERC (RGPIN-2015-05208, RGPAS-478121-15), (RGPIN-262808-2012), and EU MSCf (Project MIM, H2020-MSCA-IF-2014, GA no. 659).]
Enhanced sine wave speech with an added cue for pitch improves tone perception in Cantonese
Authors: Wu Amy , Nissenbaum Jon
Published: April 2018

Cantonese has six lexical tones (four level and two rising) that distinguish otherwise identical syllables. Although it is known that other acoustic cues besides f0 (e.g., voice quality) enter into tone perception, it is unknown whether f0 alone provides a sufficient cue. To test this, modified Sinewave Speech (SWS) replicas of Cantonese sentences were presented to listeners. SWS replaces vocal tract formants with frequency-modulated sinusoids, and has been shown to support perception of phonemic content of speech. However, because formant trajectories alone lack information about f0 and voice quality, standard SWS is unsuitable for studying tone perception (Feng et al., 2012, JASA131/EL133; Rosen & Hui, 2015, JASA138). To create the stimuli, the lowest sinusoid of the SWS replica (representing F1) was replaced with a complex tone constructed using a bandpass with the same center frequency as F1, just wide enough at any timepoint for two harmonics of an independently specified f0 contour. This two-component tone implies a missing fundamental, allowing simultaneous impression of harmonic direction and F1 direction. Modified and unmodified SWS replicas of Cantonese words were presented to native Cantonese speakers to ascertain whether implied f0 improves tone perception; preliminary results support an effect of modified SWS.
Remote acoustic detection of localized delamination in vibrating composite layered plates
Authors: Flynn Tyler J. , Dowling David R.
Published: April 2018

Adhesively bonded, layered composite materials are ubiquitous in naval, aerospace, and automotive applications. One common challenge with such materials is the presence of delamination discontinuities at the interlaminar bonds which can have severe adverse effects to structural health and system performance. Worse yet, delamination is often visually indiscernible as it occurs below visually-obstructing surface layers, making non-visual defect detection techniques attractive in comparison. In this presentation, remote acoustic detection of localized delamination in a 0.3-m-square composite laminate plate subject to 100-6000 Hz noisy broadband forcing will be investigated. Remote measurements of the radiated acoustic field from composite plates with and without known localized delamination are collected with a 15-element microphone array. Here, statistical comparisons of spectral amplitudes between plates with and without damage are then used to evaluate remote acoustic detection performance. Additional signal processing steps are applied to the raw array data to improve performance robustness in the reverberant laboratory test setting. Considerations for detection performance include minimum detectable size of delamination, robustness to receiving-array location, and sensitivity to ambient noise. [Sponsored by NAVSEA through the NEEC and by the US DoD through an NDSEG Fellowship.]
Design considerations for a compact correlation velocity log
Authors: Blanford Thomas , Brown Daniel , Meyer Richard
Published: April 2018

A Correlation Velocity Log (CVL) has some advantages (lower source level and operating frequency) over a Doppler Velocity Log (DVL) as a navigational aid for an unmanned underwater vehicle (UUV). A CVL provides a bottom referenced velocity estimate by estimating displacement using the incoherently scattered field from an acoustic projector and an array of hydrophones. A small low cost UUV generally operates in shallow water and has limited space and power available for a navigational aid, creating added constraints for the design of a CVL. The important design considerations (such as size, array geometry, operating frequency, and bandwidth) will be discussed as they relate to accuracy of the velocity estimate and operating range. [The authors acknowledge the financial support for this work by Lockheed Martin Undersea Systems.]
A Brief history of avian bioacoustics
Authors: Dooling Robert , Dent Micheal L.
Published: April 2018

A proper history of avian bioacoustics would reference early naturalists such as Aristotle, Pliny the Elder, and others who observed that birds not only have acute senses but that they also learn their vocalizations with reference to auditory information and exhibit parallels with human speech, language, and music. On the production side, the development of the tape recorder followed by the sound spectrograph enabled researchers to precisely record, preserve, analyze, and quantify the characteristics of the amplitude and spectral envelope of the acoustic signals which birds use to communicate. In the 1950s Thorpe, and later Marler, tackled the development of vocal learning in birds and the nuances of individual and species differences, which began the modern era of avian bioacoustics. Almost simultaneously, on the perception side, the confluence of Skinnerian conditioning methods, signal detection theory, and the first laboratory minicomputers launched the modern era of animal psychophysics, which continues to this day in helping to understand the striking parallels between avian acoustic communication and speech and language learning in humans.
A history of fish bioacoustics
Authors: Popper Arthur N. , Hawkins Anthony D.
Published: April 2018

Awareness of fish sound production dates back to ancient times, and concern about effects of man-made sounds on fishes can be traced back at least to the mid 17th century. By the end of the 19th century, the morphology of the fish ear had been well described, but experimental studies of the hearing characteristics did not begin until the early 1900s, when Parker demonstrated that fish can detect sounds. Subsequent work by von Frisch and his students, including Dijkgraaf, determined the range of frequencies that fishes could detect, and showed the fishes can discriminate between sounds. Later work in Europe provided a deeper understanding of sound detection mechanisms with Enger pioneering experiments on fishes in the sea. Experiments in the sea by Schuijf, Chapman, and others demonstrated that fish could discriminate sound directions. Meanwhile, in the U.S., Moulton, Tavolga, and their students documented diversity in fish hearing capabilities. Concurrently, studies by Fish, Winn, Myrberg, Tavolga, and others showed diversity in fish sounds, and documented the behaviors associated with fish sound production. Work by these investigators (and many others) opened the field of fish bioacoustics, and provided a wealth of information that stands today as the basis for modern studies.
A brief history of our understandings on underwater noise impacts to marine life and the evolution of its regulatory process in the United States
Authors: Guan Shane , Scholik-Schlomer Amy R. , Pearson-Meyer Jacqueline
Published: April 2018

It has been long understood that elevated noise is detrimental to signal detection by the anti-submarine warfare community. However, it was not until the early 1970s that similar concerns were raised regarding marine life that utilize sound for various life functions. The 1980s saw some of the first studies on effects of noise from offshore oil and gas exploration and development on marine mammals in Arctic waters. Low-frequency sources for ocean thermometry research and submarine detection over ocean basins brought additional concerns in the early 1990s on potential impacts on marine mammals from intense sources. Around late 1990s, several ad-hoc noise levels were adopted as acoustic impact thresholds of marine mammals by regulatory agencies in the U.S. Several cetacean mass stranding events that were coincidental with the mid-frequency military sonar operations and the increased awareness of ocean noise pollution accelerated research in this field in the 21st Century. Numerous studies on hearing sensitivity and noise induced temporary threshold shift or physical injuries on various marine animal taxa led to new sophisticated regulatory guidelines on assessing underwater noise impacts to marine life. In addition, recent understanding of soundscapes as environmental quality factors provides new perspectives on marine species and ecosystem conservation.
The history of marine mammal bioacoustics at the Navy Marine Mammal Program
Authors: Houser Dorian S. , Finneran James J. , Jenkins Keith , Henderson E. E. , Mulsow Jason , Branstetter Brian K. , Moore Patrick , Martin Stephen W.
Published: April 2018

The United States Navy Marine Mammal Program (MMP) has been in existence for over 50 years. Following its inception, the program quickly became involved in the study of marine mammal sensory systems and bioacoustics. Early studies included the pioneering work of C. Scott Johnson in obtaining the first behavioral audiogram in a dolphin and Sam Ridgway’s electrophysiological studies of dolphin hearing and sound production. Marine mammal bioacoustic studies grew substantially in the decades following the MMP’s inception, and included numerous investigations into odontocete biosonar, pinniped and odontocete hearing (using both behavioral and physiological methods), and the impact of human-made sound on the hearing, behavior, and physiology of marine mammals. The MMP’s bioacoustic research has significantly contributed to the Navy’s environmental stewardship mandate (i.e. to predict and mitigate the impact of Navy activities on marine mammals), the development of bio-inspired sonar systems, and the ability to assess the hearing capabilities of marine mammals in the wild, under human care, and in stranded or rehabilitation scenarios. The MMP continues its bioacoustic studies today with investments focused on bottlenose dolphin and sea lion bioacoustics, but with expansion to the passive acoustic monitoring of wild marine mammals.
The central role of Woods Hole Oceanographic Institution (WHOI) in marine mammal bioacoustics
Authors: Wartzok Douglas , Ray G. Carleton
Published: April 2018

WHOI researchers pioneered marine mammal bioacoustics. Schevill and Lawrence in 1949 made the first recordings of marine mammals, beluga whales, and in 1956 first demonstrated cetacean echolocation. Schevill later concentrated on the taxonomy and behavior of cetaceans while Watkins developed the first portable high-frequency recorder and passive and active acoustic tracking systems. Ray, Watkins, and Schevill in 1969 presented the first evidence of song in a marine mammal, the bearded seal, linked to the behavior of males in the breeding season. Watkins’ papers on vocalizations informed a generation of bioacousticians on how to interpret sonograms. He was one of the first to use the Navy’s SOSUS hydrophone array to track cetacean movements. Schevill and Watkins also inspired the research of others, both in recoding marine mammal sounds and in interpreting sound in behavior. Tyack led the development of the D-Tag, which simultaneously records vocalizations and movements of cetaceans. Ketten used CAT scans to develop hearing models for cetaceans. Sayigh advanced knowledge of delphnid signature whistles and Fristrup further developed the concept of soundscapes. Watkins and Schevill’s database of more than 20,000 vocalizations from 70 marine mammal species now resides at the New Bedford Whaling Museum, freely available to the public.
Source characteristics and variability of impulsive sources used in ocean acoustics experiments
Authors: Zeh Matthew C. , Wilson Preston S. , McNeese Andrew R. , Knobles David P.
Published: April 2018

Two types of impulsive sources were used extensively in the Seabed Characterization Experiment 2017 (SCE2017): Mk-64 Sound Underwater Source (SUS), and the Combustive Sound Source (CSS). Both of these sources rely on the release of chemical energy and hence the radiated acoustic signal is subject to variability from shot to shot. In addition, SUS activates via a pressure sensor and there is variability in the depth of activation, which translates into additional variability in the radiated acoustic signal. A pair of ship-deployed hydrophones was used during SCE2017 to record source waveforms, and in this presentation, various acoustic characteristics of these sources, such as source level, frequency content, and the nature of the time domain signals will be described in terms of their statistical variability. [Work supported by ONR.]
Distinctions among physical types of marine sediments, especially mud, and their possible fundamentals-based and heuristic models
Authors: Pierce Allan D. , Siegmann William L. , Brown Elisabeth M.
Published: April 2018

Marine sediments at different locations and depths are not necessarily similar. Distinctions are (1) sandy/silty sediments, when most particles have settled and almost every particle touches other particles, and (2) mud sediments, where the majority in a layer are suspended so that they do not touch other particles. Most theoretical and analytical modeling over the years has largely been confined to sandy/silty sediments, and some successful models, although arguably heuristic and with adjustable parameters, have emerged. There is also some speculation that such models might apply equally well for mud sediments. The present authors in recent years have concentrated on the development of a fundamentals-based model for mud sediments, although there is as yet insufficient data to adequately test its validity. The present paper speculates on what this model may have in common with models for sandy/silty sediments. There are expectations that the Mallock-Wood model may approximately apply for sound speed predictions at very low frequencies. Arguments are presented to the effect that the physics is sufficiently different for the two sediments types that a substantially different model is needed for mud sediments. One chief distinction is that the solid portion of mud sediments has a portion that is clay particles, and these have substantially different electrolytic and cohesive properties than those of quartz particles.
Magnetic resonance elastography: Status of clinical applications
Authors: Ehman Richard L.
Published: April 2018

Magnetic resonance elastography (MRE) is an imaging technology that has been available as an FDA-cleared upgrade to MRI systems since 2009. Worldwide, MRE technology has been installed on approximately 1000 MRI systems. In October 2017, the AMA approved the creation of a CPT code for MRE. In MRE, propagating shear waves in the range of 30–300 Hz are generated in tissue, and imaged with a phase contrast MRI technique. The wave images are processed with an inversion algorithm to generate cross-sectional images quantitatively depicting the complex shear modulus of tissue. The main application of MRE is currently in noninvasive diagnosis of chronic liver disease. Published studies have established the MRE is the most accurate and technically successful non-invasive modality for diagnosing liver fibrosis. Many other promising applications of MRE are being explored by investigators around the world, including assessment of diseases of the brain, heart, lung, and muscle and tumors of breast, liver, prostate, liver, and other organs. The new applications that closest adoption in clinical practice are (1) assessment of brain disease and (2) advanced diagnosis of liver disease. These new applications require acquisition sequences and processing algorithms that are more advanced than the current product MRE techniques.
Magnetic resonance elastography inversions: Technical challenges and recent developments
Authors: Manduca Armando
Published: April 2018

Magnetic resonance elastography (MRE) is a phase contrast based MRI imaging technique that can quantitatively and non-invasively measure full 3D vector displacement data from propagating acoustic waves in vivo. The data acquired allow the calculation of local values of complex shear modulus and the generation of images that depict the viscoelastic properties of tissue. Acquisitions at different frequencies can capture the dispersive behavior of these quantities, and advanced approaches attempt to map anisotropic and poroelastic properties of materials. We will discuss current approaches for the inversion of MRE data, focusing on the issues and assumptions involved, and highlight some of the challenges faced in such inversions, particularly in thin or small structures in which wave propagation is dominated by waveguide effects. We will also present results based on neural network inversions, which may have lower repeatability error and be more resistant to noise than some current approaches.
Characterization of ultrasound attenuation and angular distribution from trabecular bone phantom material using refracto-vibrometry
Authors: Rorem Benjamin A. , Mehrkens Matthew R. , Huber Thomas M. , Huber Matthew T. , Hoffmeister Brent
Published: April 2018

Ultrasound is being researched and used for diagnosing osteoporosis. Researchers use trabecular bone from humans as a test material, but such bone is bio-hazardous, not uniform, and of limited size. Recently it has been demonstrated that the open-cell polyurethane foam, known as “Sawbones” could be utilized as a substitute for trabecular bone in ultrasound studies. In the current study, rectangular slices of Sawbones trabecular bone phantom material were insonified with a 25 mm diameter 500 kHz ultrasound transducer oriented both normal to the surface and at an angle. Refracto-vibrometry (RV), an interferometric method for optically measuring ultrasound, was compared with conventional transducer measurements of ultrasound transmission through the bone phantom samples. The measurement beam from a Polytec PSV-400 scanning laser Doppler vibrometer was directed through a water tank towards a stationary retroreflective surface. Acoustic wave fronts (density variations) which pass through the ~50µm diameter measurement laser cause variations in the integrated optical path length. The measured signals were used to determine parameters such as normalized broadband ultrasonic attenuation (nBUA) at numerous scan points. This enabled measurements of the spatial and angular distribution of the transmitted ultrasonic field through the sample that are not possible using a conventional single-element ultrasonic transducer.
Multidomain modeling of acoustic transducers using SimScape
Authors: Blanford Thomas , Thompson Stephen C.
Published: April 2018

Finite element modeling of acoustic transducers can capture many complex behaviors that are neglected in simpler analyses. However, the complexity that requires finite element modeling is often confined to a small region of the total device. In that case it is possible to combine the finite element model of the subsection that requires this complexity with dynamic system modeling methods for the balance of the design. Dynamic system modeling includes earlier methods of analog circuit modeling and generalizes those methods appropriately tor acoustic transducer analysis. This paper will describe SimScape modeling of transducer structures in a way that allows combined modeling with FEA where needed. Simple examples will be selected from among moving coil speakers, balanced armature transducers, condenser microphones, and piezoelectric devices.
Spin-MEMS microphone based on highly sensitive spintronic strain-gauge sensors
Authors: Fuji Yoshihiko , Higashi Yoshihiro , Kaji Shiori , Masunishi Kei , Nagata Tomohiko , Yuzawa Akiko , Otsu Kenji , Okamoto Kazuaki , Baba Shotaro , Ono Tomio , Hara Michiko
Published: April 2018

We report a novel spintronic MEMS (Spin-MEMS) microphone, which is a new type of resistive microphone. For this microphone, spintronic strain-gauge sensors (Spin-SGSs) are integrated on a bulk micromachined diaphragm. The Spin-SGSs are based on magnetic tunnel junctions (MTJs) similar to those used as magnetic sensors in hard disk drives. In work to date, we have experimentally confirmed that the Spin-SGS exhibits a high gauge factor in excess of 5000, which is 100-fold that for a conventional poly-Si piezoresistor, by adopting a novel amorphous Fe-B-based sensing layer with high magnetostriction and low coercivity. Thanks to the high strain sensitivity of the Spin-SGSs, the Spin-MEMS microphone exhibits a signal-to-noise ratio (SNR) of 57 dB(A). A Spin-MEMS microphone with a first resonance frequency of over 70 kHz was also fabricated that exhibits an SNR of 49 dB(A), which is promising for acoustic health monitoring. In this study, we compared the operation sounds of defective and normal bearings using the Spin-MEMS microphone. The Spin-MEMS microphone detected differences in the operation sounds between the defective and normal bearings in the high-frequency range of 10 kHz to 50 kHz.
A MEMS condenser microphone based acoustic receiver for totally implantable cochlear implants
Authors: Pfiffner Flurin , Prochazka Lukas , Dobrev Ivo , Dalbert Adrian , Sim Jae Hoon , Harris Francesca , Guignard Jeremie , Walraevens Joris , Röösli Christof , Huber Alex
Published: April 2018

The goal of the present project is to develop intracochlear acoustic receivers (ICAR’s) for measurement of the sound pressure in the inner ear of human temporal bones and in acute large animal experiments. In addition, the ICAR is designed to be used as an implantable microphone for totally implantable cochlear implant (TICI) systems. The presented ICAR concept is based on a commercially available MEMS condenser microphone customized with a protective diaphragm providing sealing properties and optimized sensor head geometry for accessing the tiny fluid-filled cavities of the human inner ear. The first ICAR prototypes (PT I) have been used for numerous intracochlear sound pressure measurements in human and sheep temporal bones. The data thus obtained are in good agreement with the literature. The second ICAR prototype (PT II) was further adapted for surgical insertion in the scala tympani in acute large animal experiments. First experiments have been successfully performed and further revealed that the presented ICAR concept is a suitable receiver technology for TICI systems. Currently, the development of a fully biocompatible ICAR (PT III) is ongoing. This sensor must fulfill all important requirements of a TICI device such as high performance, low power consumption and good system integration.
Vibroacoustic simulation of hearing aid receivers
Authors: Varanda Brenno
Published: April 2018

The overall aim of this research is to develop practical vibroacoustic models of hearing aid receivers, a key electro-acoustic component of hearing aids. The receiver is a high efficiency miniature sound source which utilizes a balanced armature electromagnetic motor. A standard side effect for most balance armature receivers is structural vibration. This receiver-borne structural vibration can travel through the hearing aid package to the microphones, resulting in undesirable oscillations, just like acoustic feedback. The receiver models are used to help hearing aid designers refine vibration isolation mounts and package components to reduce both acoustic and receiver-borne structural feedback. The model consists of a simplified electro acoustic circuit-equivalent that can easily be coupled to multi-physics finite element analyses. The model has been validated against standard hearing industry measurements and proved to be effective on predicting transmissibility forces across various speaker attachments.
Hearing health across the lifespan: Prevention begins in early in life
Authors: Meinke Deanna K.
Published: April 2018

Hazardous noise exposures begin early in life and evidence of noise-induced hearing loss (NIHL) and tinnitus begins to appear in adolescence and early adulthood. In animal studies, these early noise exposures can cause permanent loss of greater than 50% of cochlear-nerve/hair-cell synapses that do not recover on their own and may contribute to greater age-related hearing loss in the future. All of the landmark studies over the past 75 years that identified the risk of NIHL in children and adolescents, ended with a recommendation for education or intervention to address the problem. In 1990, a consensus statement on Noise and Hearing Loss from the National Institutes for Health called for “a comprehensive program of education regarding the causes and prevention of NIHL should be developed and disseminated, with specific attention directed toward educating school-age children.” Today, there continues to be a need to nationally coordinate public health efforts to systematically address the prevention of NIHL in youth using evidence-based hearing health promotion based upon health communication science. Dangerous Decibels® is a successful evidence-based intervention program that has been demonstrated to be effective in changing knowledge, attitudes, beliefs and behaviors of both youth and adults for the prevention of NIHL and tinnitus.
The non-auditory health effects of chronic noise exposure: A review
Authors: Scinto Jennifer , Schnitta Bonnie , Durant John , Hudda Neelakshi
Published: April 2018

This paper serves as a review of the most recent literature on the effects of chronic noise exposure on the health of human listeners. The auditory effects of occupational and other exposure to noise have been well researched and the prevention and treatment of noise-induced hearing loss is largely understood. However, as the populations of urban areas and large city centers grow, the interest in the non-auditory health effects of exposure to environmental noise such as transportation noise, aircraft noise, and other community noise has also increased. Within the past few years, several new studies have been conducted strengthening the evidence for a link between exposure to high levels of environmental noise and ill-health, especially with regards to cardio-vascular and endocrine health, immune function, sleep loss, and mental health. The research covered in this review is inclusive of human experimental, epidemiological, and mechanistic studies. Additional research will be needed to completely assess and understand the increasingly present threat to human health that is chronic environmental noise. This review will be used as the foundation for a future study examining the correlation between ill-health and noise pollution from a nearby airport.
Exploiting both output channels of seismically decoupled infrasound sensors for enhanced transient detection and direction-of-arrival estimation
Authors: Frazier William G.
Published: April 2018

Some infrasound sensors have internal sensing capabilities that remove or permit subsequent removal of much of the effect of ground motion on the measured pressure fluctuations. This presentation explores possible enhancements to transient acoustic signal detection and direction-of-arrival estimation when data corresponding to the ground motion and pressure fluctuation signals are analyzed simultaneously using statistical array signal processing techniques. Data from three 4-element infrasound sensor arrays that were deployed to detect explosive events occurring from 10 km to 20 km distant are used as the basis for the study.
Comparison of temporal processing in the auditory brainstem neurons between acoustic and electrical hearing
Authors: Müller Michaela , Beiderbeck Barbara , Grothe Benedikt , Pecka Michael
Published: April 2018

Spatial hearing is essential for communication as well as navigation in everyday life. Unfortunately, sound localization in these complex environments is severely limited in patients with bilateral cochlear implants (CIs) and its restoration thus remains one of the central obstacles of CI research. Spatial sensitivity is generated by neurons in the brainstem that detect differences in the arrival time between excitatory and inhibitory inputs from the two ears on the scale of only microseconds. However, the mechanisms underlying this precise temporal integration of individual inputs and potential differences in temporal precision during electrical stimulation are still not understood. Here, we obtained in vivo electrophysiological recordings from single neurons in the brainstem of Mongolian Gerbils (Merionesunguiculatus). We characterized the temporal precision of action potential firing in response to click trains in binaural neurons of the Lateral Superior Olive and their upstream inputs (auditory nerve, cochlear nucleus and medial nucleus of the trapezoid body). To assess potential differences in temporal precision between acoustic and electrical stimulation, complementary data are obtained in normal hearing animals and animals that underwent cochlear implantation. Ultimately, we aim to identify basic principles of binaural integration in the auditory brainstem during acoustic and CI-based spatial hearing.
Measurements and models of auditory nerve spike rate and timing to electrical stimulation
Authors: Bruce Ian C.
Published: April 2018

Physiological measurements of the response of auditory nerve (AN) fibers to electrical stimulation from a cochlear implant (CI) have in general exhibited much higher maximal entrainment rates and higher temporal precision than is observed for acoustical stimulation. However, it appears that this superior rate coding in the AN for electrical stimulation does not translate to better coding of rate in the midbrain or for the percept of temporal pitch. Similarly, the enhanced temporal precision for electrical stimulation does not lead to improved coding of interaural timing differences. In this talk, I will review physiological data and computational model simulations that indicate that the superior spike rate and timing representation for CI stimulation may only hold when considering the response of some single AN fibers to repeated identical stimuli. In fact, there is a large heterogeneity in spiking responses that can change dramatically as a function of stimulus current level. A multi-compartmental computational model will be used to demonstrate how the electrode- fiber geometry and the membrane biophysics could be contributing to these phenomena. I will also discuss the implications of the likely population response of the AN to CI stimulation for brainstem processing. [Work supported by NSERC Discovery Grant 261736.]
Comparisons of electric and acoustic ITD coding in normal hearing gerbils
Authors: Vollmer Maike
Published: April 2018

Small differences in the arrival time of sound between the two ears [interaural time differences (ITDs)] provide important cues for directional hearing and speech understanding in noise. Deaf subjects with bilateral cochlear implants (CIs) show relatively poor sensitivity to ITDs. It is unclear whether these limitations are due to differences in binaural brain circuits activated by electric compared to acoustic stimulation, mismatches in electric activation site across ears, or deafness-induced degradations in neural ITD processing. To identify potential limitations of electric ITD coding, we compared electric and acoustic ITD coding (i.e., ITD tuning and discrimination thresholds) in the same population of auditory brainstem and midbrain neurons in normal hearing gerbils. When compared in the same neurons, ITD coding to acoustic stimulation did not predict coding to electric stimulation. However, on a population level, neurons demonstrated surprising similarities in acoustic and electric ITD processing. Importantly, even short periods of deafness (2 weeks) severely degraded electric ITD processing. The findings suggest that discrepancies in ITD discrimination between bilateral CI users and normal hearing listeners are primarily due to deafness-induced changes in neural ITD processing rather than differences in the binaural brain circuits activated by either electric or acoustic stimulation.
Acoustic communication by vocal tract modulation
Authors: Story Brad H.
Published: April 2018

In both human and nonhuman animals, the airway system may serve as an instrument for acoustic communication. Flow-induced tissue vibrations and noise sources generate the acoustic excitation, whereas the configuration of the vocal tract provides a variable resonant filter system that transforms the excitation into a “message.“ This presentation will describe the development of a vocal tract model in which the effects of articulatory movements that produce speech are generated by specifying independent acoustic events along a time axis. These events consist of directional changes in the first three resonance frequencies of an acoustically-neutral airway configuration and are transformed, via acoustic sensitivity functions, into time-varying modulations of the vocal tract shape. The duration of each event may be considerably overlapped in time with other events to produce efficient transmission of information through the effects of coarticulation. The model will be used to demonstrate construction of syllables, words, and phrases based on a range of underlying idiosyncratic “neutral’’ vocal tract configurations representative of typical and unusual airway systems. [Research supported by NIH R01-DC011275, NSF BCS-1145011, and NIH R01-DC006282.]
The challenges of developing articulatory synthesis models of early vocal production in humans
Authors: Plummer Andrew R.
Published: April 2018

At birth, human infants can cry, but they cannot articulate anything like the sound patterns of their mothers' speech that they have been hearing in the last month or so in the womb. Learning to speak involves a re-tuning of the muscle systems for breathing, crying, and suckling in order to be able to articulate a rapid sequence of exquisitely coordinated movements of the speech articulators—gestures of the larynx, velum, tongue, and lips—in synchrony with a lengthened expiratory phase of the breathing cycle, to acoustically shape the air flowing from the lungs to produce the sound patterns that are the words of a specific language. Models of speech production developed using data on articulator movement and coordination in adults cannot be applied directly, because this learning takes place in the context of substantial changes to the size and shape of the vocal tract over the course of physical maturation. This talk describes the changes in vocal tract morphology in human development, and then reviews how articulatory synthesis systems developed for adults have been adapted to model the expanding repertoire of vocalizations that have been observed in infants with normal hearing over the first year of life.
Synthetic time reversal and remote acoustic sensing of changes in a vibrating structure
Authors: Dowling David R. , Flynn Tyler J.
Published: April 2018

Synthetic time reversal (STR) is a method for blind deconvolution that is based on the time-reversal symmetry of acoustic fields. It can be used to estimate an unknown acoustic source’s broadcast waveform in an unknown multipath environment from remote transducer array recordings. This presentation will review the formulation of STR, and its use in ocean acoustics and non-destructive evaluation. In particular, experimental results are presented for the remote acoustic detection of mechanical changes to a vibrating 0.3-m-square by 3-mm-thick aluminum plate in a reverberant environment. The plate has nominally clamped edges and is subject to swept-frequency base excitation from 100 to 2,000 Hz. Sound radiated from the plate with and without a mechanical change is recorded remotely with a 15-microphone linear array and processed using STR to reconstruct a single radiated-sound signal that is deconvolved from the environment’s unknown reverberation response at signal-to-reverberation ratio levels of -7 to -13 dB. The corrected signals are processed to detect boundary clamping defects and various length cuts in the plate via standard statistical baseline comparison techniques. Detection results using STR are superior and more robust to geometrical uncertainties than equivalent results from conventional approaches. [Sponsored by ONR and NAVSEA through the NEEC]
Multiple time-reversal focusing with a virtual source array
Authors: Byun Gihoon , Song H. C. , Kim J. S.
Published: April 2018

Time reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by backpropagating a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of the PS has been partially relaxed by the concept of a virtual source array (VSA) [J. Acoust. Soc. Am. 125, 3828–3834 (2009)]. A VSA can serve as a remote platform or lens and redirect a focused field to a selected location beyond the VSA for which the field is assumed as a homogeneous medium with constant sound speed. The objective of this study is to extend VSA-based single TR focusing to simultaneous multiple focusing. This is achieved using the optimization theory by employing the multiple constraints method derived from a constraint matrix, which consists of appropriately synchronized transfer functions. It is found that simultaneous multiple focusing can be achieved with distortionless response at selected multiple locations, and its performance degrades in the presence of sound speed mismatch. Possible applications for the VSA-based TR focusing are discussed, and numerical simulation results are presented
The architect as Ally: A multi-sensory approach to design
Authors: Miller Gregory A. , Glosemeyer Petrone Robin S.
Published: April 2018

The end product of an architectural acoustic design is not the quality of the documentation or the successful achievement of a set of parameters, but rather the experience of the end users. With rare exception, the perception of acoustic characteristics cannot be separated from the users’ visual and tactile experiences. To unify these sensory experiences, we have adopted an approach to acoustic design that fully embraces the architect’s spatial and material vision for a building. At the same time, we seek to educate the architect so that they can embrace and internalize the acoustic goals of the building in their work. This presentation will describe our overall design approach, means of communication and demonstration used to build conviviality with our clients, and examples where acoustic and architectural goals have coincided.
Acoustical conflicts and synergies with energy efficient building design
Authors: Muehleisen Ralph T.
Published: April 2018

In the US, commercial and residential buildings consume more than 40% of the total energy and more than 75% of all electricity, contributing greatly to carbon emissions. In order to reduce both carbon emissions and reduce utility costs, buildings are being designed and constructed with much higher efficiency than even just a decade ago. Indeed, a “net-zero-ready“ building is both possible and even affordable. Some design strategies can also improve building acoustics but others are detrimental. In this talk, synergies and conflicts of acoustics and energy efficient design are discussed. In particular, well-sealed building envelopes and use of high performance windows can provide both acoustic and energy benefits. However, the use of natural ventilation is at odds with acoustics. In this talk, the conflicts and synergies of these high efficiency building treatments are presented.
Sound of wood-boring larvae and its automated detection
Authors: Sutin Alexander , Yakubovskiy Alexander , Salloum Hady , Flynn Timothy , Sedunov Nikolay , Nadel Hannah , Krishnankutty Sindhu
Published: April 2018

Stevens Institute of Technology has been investigating solutions for instrumental detection of invasive species at ports of entry. Stevens has built several acoustic systems for detection of acoustic/ vibrational signals produced by insects. This paper presents acoustic signals recorded in tests conducted in APHIS Otis Lab using tree bolts infested by Asian Longhorn Beetle, ALB and Emerald Ash Borer, EAB larvae. The analysis of the recorded sounds extracted the signal features that allowed larval classification. These features include frequencies of the generated pulses, their durations and frequencies of pulse envelops. These features showed a clear separation of ALB and EAB. For example, the main frequency of the ALB sound was in the range of 3.8–4.8 kHz, while for EAB it was between 1.2 and 1.8 kHz. A preliminary algorithm for automated insect signal detection was developed. The algorithm automatically detects pulses with parameters typical for the larva-induced sounds and rejects non-insect sound pulses. Detection is announced when the number of detected pulses for some time (5 min) exceeds the definite threshold. In the conducted test, this algorithm provided detection of a larva in all tested samples without false alarms. [This project was funded under contract with the U.S Department of Homeland Security (DHS) Science and Technology Directorate (S&T), contract HSHQDC-10-A-BOA35.]
Ultrasonic Transmission Behavior in Posidonia oceanica Rhizomes
Authors: Johnson Jay R. , Hermand Jean-Pierre , Wilson Preston S.
Published: April 2018

The roots and rhizomes of seagrass can form a complicated multi-phase layer within sediments. Gas channels in the rhizomes, known as aerenchyma, give rise to a complicated acoustic response. A model for acoustic propagation through such rhizomes would be beneficial for acoustic remote sensing communities. Ex situ measurements of the ultrasonic sound speed through the dense woody structure of the rhizomes of the seagrass Posidonia oceanica are presented. Ultrasonic (1–5 MHz) time-of-flight measurements were made with the rhizomes segments aligned both lengthwise and crosswise to the propagation direction of the acoustic pulse. The acoustic behaviors of plants collected from different locations in the Mediterranean are compared to each other and to the behaviors of the associated leaf blade tissues. Two measurements were also made of rhizomes before and after degassing the aerenchyma, to quantify the effects of entrained gasses on acoustic behavior. [Work supported by ONR and ONR Global.]
Sound speed profiles in the global ocean calculated from WOCE data
Authors: Acharya Mukunda , Zhang Likun
Published: April 2018

Sound speed in the stratified ocean varies continuously with the depth. The sound speed profile reaches a minimum at a depth, that is typically 1 km in mid-latitude to form a sound channel. In this study, the CTD data collected in the World Ocean Circulation Experiment (WOCE) are used to calculate around 6,000 sound speed profiles over the global ocean. The data of conductivity, temperature and pressure at different depths are from measurements at intervals typically in 55 km by different cruises. Sound speed is examined from the data in each cruises. By analyzing sound speed profiles, sound speed minimum and the depth for this minimum are characterized as a function of latitude ranging from 70-degree south to 70-degree north. The results show a well determined pattern. Sound speed distributions over the global ocean at various depths in shallow water are also examined.
Estimating liver fat fraction from ultrasonic attenuation and backscatter coefficient measures in adults with nonalcoholic fatty liver disease
Authors: Albelda Lucia , Han Aiguo , Sy Ethan Z. , Andre Michael P. , Loomba Rohit , Sirlin Claude B. , Erdman John W. , O'Brien W. D.
Published: April 2018

Between 80 and 100 million people in the United States suffer from nonalcoholic fatty liver disease (NAFLD). It is currently being diagnosed via MRI and biopsies; however, these tend to be expensive and painful. In this study, a Siemens 3000 ultrasound scanner was used to obtain the quantitative ultrasound (QUS) parameters [backscatter coefficient, BSC, and attenuation coefficient, AC] of 84 participants with known or suspected NAFLD (thus few uncompromised liver samples expected). Participant recruitment is continuing. Also obtained was the liver proton density fat fraction (PDFF) via MRI. AC and BSC individually were linearly correlated (~0.6) to PDFF. The data were then divided into two equally sized sets, training and test, in order to calculate PDFF from a function of AC and BSC. Using the training set a polynomial equation was created where AC and BSC were used to estimate PDFF. It was found that a polynomial 1,2 [AC,BSC] yielded an improved correlation (0.76) when evaluated using the test set. Significant improvement is obtained to estimate PDFF using both AC and BSC as opposed to using either of these QUS parameters separately. [Support: NIH R01DK106419 and NIH R37EB002641.]