bluuebunny/crossref_metadata_2025 huggingface dataset:
Hunt-ing for new therapies: From red blood cells to acoustic nanobubbles
Authors: Coussios Constantin
Published: November 2017

The Acoustical Society has undoubtedly nurtured me through all key stages of my career. I attended my first ASA meeting as the last doctoral student of noise acoustician Prof. Shôn Ffowcs Williams, working on acoustic scattering from red blood cells to detect hemolysis. At a time when I was questioning whether research in general and acoustics in particular were right for me, the unexpected award of the biomedical acoustics student prize (Atlanta, 2000) and a chance meeting with my future Hunt fellowship mentor, Prof. Ron Roy, radically changed my outlook. Until that point, my perception of biomedical acoustics had been confined to diagnostic applications, but discovering the emerging therapeutic potential of focused ultrasound and acoustic cavitation made me realize that it was possible for an acoustician to impact key aspects of human health, such as treating cancer or facilitating orthopedic surgery. Much of the training and inspiration of my Hunt fellowship year at Boston University (2002–2003) travelled back with me to Oxford when I set up the BUBBL research group, which over a decade and following further encouragement by an ASA R. Bruce Lindsay award (2012) enabled my team and me to translate novel acoustic therapeutic technologies into clinical practice.
The Hunt Fellowship: Inspiring acoustics professionals of the future
Authors: Stimpert Alison K.
Published: November 2017

Students may exit a Ph.D. program feeling fatigued, and sometimes a bit directionless professionally. These feelings combined with the challenging academic job market could be part of the reason for this time period being one of the biggest “leaks in the pipeline,” for women scientists in particular. The flexibility and generosity of the Hunt Fellowship can be inspiring at this crossroads of a young scientist’s career. As the 2009–2010 Hunt Postdoctoral Research Fellowship recipient, I studied the acoustic behavior of humpback whales on their Antarctic feeding grounds, working under the mentorship of Dr. Whitlow Au (University of Hawaii) and Dr. Douglas Nowacek (Duke University). This project followed seamlessly from my dissertation, yet brought me to new ecosystems and reinvigorated my research questions with surprising data. The signal processing skills I gained in acoustic and animal movement analysis solidified my interest in quantitative acoustic behavior research and I made strong connections with several interdisciplinary research groups. This all fueled my career path toward my current Research Faculty position at Moss Landing Marine Laboratories, using similar sound and movement tags to study the effects of anthropogenic noise on cetaceans in general.
Frederick V. Hunt Postdoctoral Research Fellowship: My journey toward clinical research in audiology
Authors: Diedesch Anna
Published: November 2017

As the current Hunt Postdoctoral Research Fellow, I am evaluating binaural cue distortion in hearing aids at the VA RR&D National Center for Rehabilitative Auditory Research. Beginning early in life I always wanted to teach. Ironically, during my undergraduate education I felt that would require too much education. I instead found the field of Audiology and was fascinated by the science and technology in the field as well as rewarded by being able to treat and counsel patients regarding their hearing difficulties. While working on my Doctor of Audiology, I became aware of the difficulties in our field to train clinical researchers who would return to academia to train the next generation of audiologists. I was hesitant to pursue a Ph.D., so instead took a job as a Research Audiologist while I figured out my next step. With the guidance from Frederick J. Gallun and Marjorie Leek, I eventually began my Ph.D. with G. Christopher Stecker. This poster explores my journey toward becoming a clinical researcher and how the Hunt Fellowship is influencing my career trajectory.
A big dilemma: Airport noise and property value
Authors: Yildirim Yalcin , Villupuram Sriram
Published: November 2017

Even though many attributes to the airport creates value for properties, many other factors such as noise is considered to have wither neutral or negative effects residential property values. This research examines the relationship between airport noise and housing prices by using disaggregated transactions in Dallas-Fort Worth Airport which is the fourth busiest airport in the United States (FAA, 2015). The effects of airports on residential property values have been studied in several fields and contexts. Tomkins et al. (1998) examined the Manchester Airport by performing hedonic method. In addition, Nelson conducted a meta-analysis about noise and housing price near airport and these studies applied census tract aggregated data. This paper examined the implications of the airport noise on disaggregated residential property transactions in a rapid growing urban area—Dallas Fort Worth Metropolitan- by performing Multi-Level-Modeling. To do this, variables are defined for each level. Property level is considered with many characteristics such as number of bedrooms, bathrooms, floor, etc. Moreover, there are also neighborhood attributes such as demographics, income, and green space to evaluate. Based on results, total and marginal benefits of noise reduction were estimated that a 1 dB noise reduction may lead to increase 0.6% of house values.
Enhancing the convergence of multipole expansions at intermediate frequency
Authors: Zhou Hui , Mui Emily , Thompson Charles
Published: November 2017

In this work, we examine near-field acoustic wave scattering from media having a spatial variation in compressibility contrast. Typically, the scattered acoustic pressure can be expressed as a convergent Neumann series when the compressibility contrast is relatively small. However as the magnitude of the compressibility contrast increases a resonant scattering condition ensues, yielding a divergent series. It has been shown that Padé Approximants method can be used in these cases, thereby extending the range of utility of the Neumann series solution. The proposed research explores hybrid methods that combine multipole-methods, and Padé Approximant approaches to calculate the near-field scattered pressure. As part of this work, we will examine the low-frequency breakdown in the plane wave, and monopole-monopole expansion approaches as it affects the numerical stability of spatial translation operations.
Daylong acoustic amplitude from the perspective of young children with and without hearing loss
Authors: VanDam Mark , Heid Haille , James Stephen , Schraven Samantha , Driscoll Danette , Hardie Amy , Cahill Stacy , Olds Daniel
Published: November 2017

Very little is known about the acoustic characteristics of the daylong auditory environment of children, especially for those children who belong to an at-risk population such as those with hearing loss. This work looks at the daylong acoustic amplitude from the auditory perspective of young children. Naturalistic audio was collected from a wearable audio recorder. Amplitude values were collected from 814 daylong recordings from children aged 1–90 months, with 318 from children who are typically developing and 496 from children with mild- to moderate hearing loss. We compared for difference by sex, hearing status, and age. Results suggest that boys’ recordings had higher amplitude than girls’, and that recordings of children with mild- to moderate hearing loss had higher amplitude than children who were typically developing. There were no observed sex by hearing status or sex by age interactions. For the recordings from children with hearing loss amplitude was negatively correlated with age, but for typically developing children amplitude was positively correlated with age. Results may be important for better understanding of children with hearing loss, language and speech development, automatic processing routines (such as automatic speech recognition), and intervention or therapeutic techniques for at risk populations.
Environmental calibration curves
Authors: D'Spain Gerald L. , Rimington Dennis , Yuan Shih-Hsuan (Shane) , Helble Tyler A.
Published: November 2017

Sound propagation through the ocean causes distortion of the received waveform, characterized by the impulse response of the channel (which often assumes a fixed medium since ocean Mach numbers are so small and the temporal scales of oceanographic variability typically are much larger than signal travel times). In addition, noise, both its level and temporal character, impact signal detection and processing. The purpose of this presentation is to describe a physics-based approach to developing environmental calibration curves to account for environmental effects in the received field. The methods are first applied to passive acoustic recordings by fixed, single-hydrophone packages deployed in the Southern California Bight. Five types of baleen whale calls from blue, fin, and humpback whales are the signals of interest. Results show that these environmental calibration curves, determined by the probability of detection, are most sensitive to sediment thickness over the blue and fin whale frequency band, whereas they are most sensitive to sediment type for humpback calls. The statistical framework for estimating the mean, bias, and variance of these environmental calibration curves also is discussed. [Research supported by the Living Marine Resources Program, the Office of Naval Research, and the Joint Industry Programme.]
Speech intelligibility studies in a historic multipurpose room
Authors: Jaramillo Ana M. , Nelson Peggy B. , Olson Bruce C.
Published: November 2017

The Speech-Language-Hearing Sciences department at the University of Minnesota is located in Shevlin Hall, a historic building dating from the 1920s. Shevlin Hall has a large room on the first floor with a high coffered ceiling that is often used for receptions and presentations but also serves as a classroom. Students with hearing loss often complained about attending classes in Shevlin 110 due to its high reverberation times, combined with window AC unit noise, resulting in very degraded speech intelligibility. In 2013, the room went through renovations that addressed room acoustics, sound system design, as well as lighting and equipment (not including AC). Post-renovation measurements and subjective impressions have shown a significant improvement in speech intelligibility in the room. For this paper, we are looking at subject-based intelligibility tests to compare with prediction metrics and simulations, as well as collecting a qualitative narrative on the department’s impression on the room before and after renovations.
Acoustical renovation and sound system design in a church in buenos aires, argentina
Authors: del Solar Dorrego Fernando M. , Gardella Pablo
Published: November 2017

Church “Nuestra Señora de la Paz” suffered from an excessive reverberation (4 seconds at mid-frequencies) and an ill-suited sound reinforcement system. Measurements of the Speech Transmission Index (STI) in the congregation area indicated that speech intelligibility was greatly impaired. Thermal insulation on the roof was insufficient and impacted in air conditioning costs. Renovations included the design of a sound-absorbing and thermally insulating covering in the roof area. Subsequent measurement of room acoustic parameters showed that the proposed goals were met. A new sound system, which increased speech intelligibility and audio quality substantially, was designed and tested. The possible appearance of acoustical defects after the renovation, such as echoes and flutter echoes, was studied using objective tests on the measured Room Impulse Responses (RIRs).
Active learning classroom configurations and the effects on speech intelligibility
Authors: Skorski Edwin S.
Published: November 2017

For high academic achievement, it is critical that the acoustic environment of classrooms and other learning spaces provide the proper conditions for good speech communication between teacher and students. While there is a significant body of research regarding traditional classroom seating arrangements, less is known regarding the acoustical impacts of “active learning classroom” configurations. Active learning classrooms are typically furnished with mobile tables and chairs that are easily reconfigured in a variety of learning arrangements. Additionally, in an active learning environment, there is typically no fixed position from which the teacher will lecture. While active learning spaces provide flexibility and mobility, which is advantageous for student engagement, they also create a complex acoustic environment where both source and receiver positions have a continually shifting spatial relationship. Using design guidelines found in ANSI/ASA S12.60-2010/Part 1, this study will use computer simulated environments to explore various active learning space configurations and compare the results to generally accepted acoustical performance criteria for RT, C80, STI, and RASTI.
Temporal features of conditioned reduction in dolphin auditory brainstem responses
Authors: Finneran James J.
Published: November 2017

Conditioned changes in the hearing of two bottlenose dolphins were elicited by pairing a 10-kHz conditioned stimulus (i.e., a warning sound) with a more intense, unconditioned stimulus at 80 kHz. Hearing was assessed by measuring transient auditory brainstem responses (ABRs) to tone burst stimuli presented with inter-stimulus intervals drawn from a random distribution with mean interval of 2 ms and 2-ms jitter. Tone burst frequencies were 57, 80, 113, and 133 kHz. ABRs at discrete times within each trial were obtained by synchronously averaging epochs of the instantaneous electroencephalogram time-locked to tone burst onsets over 2 to 3-s time intervals. In initial testing with one dolphin, ABRs were reduced after the conditioned stimulus but before the unconditioned stimulus, demonstrating a conditioned suppression of the ABR. In subsequent testing, and in all testing with the second dolphin, ABRs were suppressed (relative to baseline values) throughout the entire 31-s trial. When the unconditioned stimulus was removed, ABRs returned to baseline values, demonstrating extinction of the conditioned response. The results support the hypothesis that some toothed whales can “self-mitigate” the effects of noise if warned of an impending exposure. [Work supported by SSC Pacific NISE Program.]
Predicting acoustic backscattering from bioturbated seafloors
Authors: Johnson Shawn
Published: November 2017

Seabed roughness is an important property for high-frequency scattering. However, for certain littoral environments, the surficial roughness of the seabed is often continuously being modified by hydrodynamic and biologic forces. For example, ocean surface waves may create orbital ripples on sand seafloors which are characterized by anisotropic roughness, and acoustic scattering from such a seafloor would be strongly aspect-dependent. Yet bottom-dwelling organisms rework the sediment, returning the structured seabed relief to random isotropic roughness, where acoustic scattering is more uniform with respect to the aspect ensonified. In this talk, we will utilize both analytic expressions as well as procedural generation methods to predict the two-dimensional roughness equilibrium power spectra of rippled and bioturbated seafloors, and the resulting impact on acoustic scattering prediction.
Sonar observations of biological activity in marine sediments
Authors: Jackson Darrell
Published: November 2017

This talk will begin with a review of past experiments using bottom-mounted, rotating sonars to observe temporal change in the seafloor. These measurements were conducted at 40 kHz and 300 kHz, and provide images of change as represented by ping-to-ping correlation. Time scales of change vary greatly with frequency and sediment type, with changes occurring over weeks at 40 kHz at a silty site and over minutes at 300 kHz at a sandy site. Finally, the level of scattering due to relic tubes, shells, etc., will be compared to that of live animals. The conclusion is that it is easiest to observe the cumulative effects of biological activity, but techniques are available to isolate current activity.
An exploration of the urban design possibilities offered by soundscape theory
Authors: Siebein Gary W. , Paek Hyun , Siebein Gary , Siebein Keely , Roa Marylin , Miller Jennifer R.
Published: November 2017

The basic concepts of soundscape theory including soundmarks which are the acoustical equivalent of landmarks, keynote sounds which are the typical sounds in a vicinity; and sound signals or the specific acoustic events that comprise the ambient sound were presented by Schafer (1977) and Truax (2001). These concepts offer ways to document, analyze, and design the acoustical qualities of urban places similar to the way that the concepts developed by Kevin Lynch in the Image of the City (1960) did for the visual character of cities. The urban design potential of soundscape theory lies in identifying the ecological relationships linking sources of sounds, prospective listeners of sounds, and the “coloration” of the sounds by the urban environment that gives unique identities to localities within a city. An acoustical community is formed by the parties who are related by the need for various forms of tangible and intangible communication in an urban setting. Case studies of an entertainment district in a city, the initial planning of a new town and the redevelopment of a city park will be used to illustrate the methods and applications of this theory to enhance the aural and urban design of cities and towns.
Effects of simplified atmospheric profiles on short range infrasound propagation
Authors: Lammers Andrew , Swearingen Michelle E.
Published: November 2017

Meteorological profiles strongly influence the propagation of infrasound signals. Much of the infrasound literature has focused on long-range (>250 km) propagation; however, there is interest in short-range (<150 km) propagation from an infrastructure monitoring standpoint. Therefore, understanding the effects of meteorological profiles is crucial. This paper focuses on simplified vertical temperature and wind profiles up to 20 km altitude and their effect on an infrasonic signal emanating from an arbitrary point source. A wide-angle, finite-element PE model that correctly handles discontinuities in wavenumber is used for calculating transmission loss. A large number of simulations were performed to investigate the effect that temperature and wind profiles in different layers of the atmosphere have on surface transmission loss and to assess the sensitivity of varying these profiles. A discussion of the results of these simulations are presented as well as an overview of temperature profiles used in this study.
The effect of listener motion on localization of tones in a room
Authors: Macaulay Eric J. , Magann Jack C. , Hartmann William M.
Published: November 2017

Listeners reported the perceived azimuths of 36 sine-tone sources in a room. For some trials, listener motion was forbidden and for others unstructured head and torso motion was encouraged with the listener remaining seated. Tone frequencies were 500, 1000, 2000, and 4000 Hz. Onsets and offsets were masked, leaving a steady-state duration of 7.6 s for exploration. It was found that the benefits of motion on source localization accuracy were clearly frequency dependent. Dynamic interaural cues were obtained from probe-microphone ear-canal recordings. Interaural cues were combined with head-tracker orientation data to predict perceived azimuths according to diverse hypotheses. Responses and interaural cues for trials without motion were used to predict a dynamic inferred location within the room for runs with motion and to identify stable inferences. Analysis of front/back confusions was conducted based on the regression between changes in interaural level differences and changes in head angle sampled at 76 instants. Except for 4000 Hz, the slope of the regression was significantly different depending on whether responses were in the front or back of the room. For interaural time difference, significance was limited to 500 and 1000 Hz. [Work supported by the AFOSR.]
Diagnostic value of experimental parameters for measurement of localization ability
Authors: Scharine Angelique A. , Domanico Morgan C. , Foots Ashley N. , Mermagen Timothy J.
Published: November 2017

This research examines the test parameters in two methods proposed by an ANSI/ASA working group for measurement of auditory localization with tactical communications and hearing protection systems (TCAPS). The localization task consisted of responding to pink noise bursts (0.250s and 7000s). Participants responded by pointing to the perceived source with a laser pointer mounted on an instrumented chair. 12 participants completed the study—half of the trials while wearing no headset and half while wearing an active Invisio X5 headset. Method 1 used four pairs of loudspeakers, separated by 8°, 10°, or 12°, and the listener was tested in two orientations (0° and 45°). Intended for use in untreated acoustic environments, Method 1 provides only a coarse estimate of localization accuracy and proportion of front/back errors. Method 2 used 36 equally spaced loudspeakers, a sound treated environment, and a chair instrumented with a laser pointer. Performance is compared as a function of separation between loudspeaker pairs in Method 1 and test method. The analyses include measures of bias, magnitude, and whether errors are due to poor acuity or front/back confusion. The utility of the proposed test configurations to assess the effects of headgear on auditory spatial awareness will be discussed.
The influence of regional identity on appalachian intonation
Authors: Reed Paul E.
Published: November 2017

In a study of intonation in Appalachian English (AE), Greene (2006) suggested that relative frequency and phonetic realization of pitch accents might reflect a stronger regional identity. The present study tests these observations, using rootedness—defined as one’s orientation to place—as a means to describe observed intonational variation. Data were drawn from sociolinguistic interviews with 25 AE speakers from northeast Tennessee. In addition to the interview, every participant completed a Rootedness Metric, a psychometric survey designed to quantify place-based orientation. To consider the extent how AE speakers compared to the broader South, this cohort was also compared to a non-Appalachian Southern cohort. A section of speech from each speaker was labeled following MAE-ToBI conventions (Beckman et al., 2005). Pitch accent frequencies were totaled. Additionally, tonal peak alignment for the L + H* pitch accents was measured. Results indicate that AE speakers have a greater occurrence of L + H* pitch accents (p<0.001), and that the tonal peak occurs earlier in the syllable (p<0.005) compared to speakers of other Southern varieties. Within the AE cohort, both older and more rooted speakers have more frequent L + H* occurrence (p<0.001), while males (p<0.01), and more rooted speakers (p<0.004) have earlier peak alignment.
Prosodic and segmental cues to regional dialect variation in American English
Authors: Smiljanic Rajka , Clopper Cynthia G.
Published: November 2017

Historically, most research on regional variation in American English (AE) examined lexical and segmental sources of variability. Focusing on prosodic variation, we have demonstrated significant effects of regional dialect on overall articulation rate, distributions of pauses, pitch accents, phrasal-boundary tone combinations, and syllable-to-syllable vowel and consonant duration variability (Clopper & Smiljanic, 2015, 2011). In this talk, we examine whether native AE listeners utilize prosodic and segmental cues to classify AE talkers by region and whether listener familiarity with different dialects affects classification. Using free classification with unmodified, monotone (flattened F0), and low-pass filtered (removed segmental information) stimuli, listeners from Ohio and Texas grouped 60 talkers based on perceived regional similarities. Listeners were more accurate in classifying talkers with the unmodified and monotone stimuli than with the low-pass filtered stimuli. There were no differences between the two listener groups in accuracy. Multidimensional scaling analyses indicated that listeners used gender and region as salient dimensions in classifying talkers in the unmodified and monotone conditions, but not in the low-pass filtered condition. The results suggest that segmental cues facilitated classification whereas intonation and global temporal cues on their own did not. The relationship between acoustic-phonetic features and classification patterns will be discussed.
Perception of phonetic imitation of Southern American English by Midwesterners
Authors: Clopper Cynthia G. , Dossey Ellen
Published: November 2017

Phonetic imitation has been observed across regional dialects in English, French, and Mandarin. This cross-dialect imitation is affected by social factors, including dialect prestige and social salience of the linguistic variables. The goal of the current study was to explore the perception of phonetic imitation of Southern American English by native speakers of Midwestern American English in a word shadowing task. The magnitude of the Midwesterners’ phonetic imitation was assessed using an AXB perceptual discrimination task, in which a different group of Midwestern listeners was asked to identify either a baseline read token or a shadowed token as more similar to the model token. The results of the AXB task revealed evidence of overall imitation, consistent with acoustic measures of imitation in word durations, vowel formant frequencies, and vowel formant trajectories. Moreover, perceived imitation was weaker for shadowers who were told where the model talker was from (i.e., Louisville, Kentucky) than for shadowers who were not provided with any information about the model talker, suggesting that explicit information about the model talker’s dialect background can shape the magnitude of cross-dialect phonetic imitation. The specificity of this cross-dialect phonetic imitation across acoustic domains and vowel variables will be discussed.
Acoustically quantifying /ai/ monophthongization in four southern dialect regions
Authors: Olsen Rachel M. , Olsen Michael , Renwick Margaret E.
Published: November 2017

The Atlas of North American English describes four southern U.S. dialect areas: Inland South (IS; interior Appalachia), Texas South (TS; around Dallas), Florida (FL), and South (S; remainder of Southern US). These areas are distinguished by degree of /ai/ monophthongization, the Southern Vowel Shift’s (SVS) triggering feature (Labov et al., 2006). IS is argued to be most advanced in the SVS, and /ai/ weakens in all phonetic environments. While not as advanced generally, TS also features all-environment weakening. In S, /ai/ weakens only in syllable-final and pre-voiced conditions, and in FL it remains diphthongal. This study uses the Digital Archive of Southern Speech (DASS) to acoustically measure /ai/ weakening in each region. Speech was force-aligned and F1 and F2 values collected at five time points. Related work on F2 formant angle in DASS speech has suggested /ai/ weakens most in IS (Renwick and Stanley, 2017). Here, trajectory length (TL) measurement (Fox and Jacewicz, 2009) corroborates evidence for regional effects on diphthong dynamics, where longer TL corresponds to more diphthongal production. Mixed modeling suggests that IS and TS speakers monophthongize /ai/ more than those in S and FL. The effects of phonetic environment, race, and gender are also explored.
A preliminary examination of the gender role in back-vowel fronting in Central Louisiana
Authors: Shport Irina A.
Published: November 2017

In addition to the Southern Vowel Shift that involves /ɛ ɪ/ fronting, high back vowels also tend to be fronted in white Southern U.S. speech (Labov, Ash, & Boberg, 2006; Thomas, 2001). The tense /u/ is the first to shift in the back-vowel system, followed by the lax /ʊ/. Gender effect on the degree of fronting has been reported for one vowel but not the other: Male speakers lead in /u/fronting, whereas /ʊ/ fronting occurs more or less uniformly across speakers of different genders (Clopper, Pisoni, & de Jong; Fridland, 2001). This study provides a preliminary examination of the role of gender in the relative degree of back vowel fronting in young adult speakers from Central Louisiana. They were recorded producing words with target vowels in a variety of tasks: word list and passage reading, sentence creation, and informal conversation. The formant values were analyzed with a reference to other vowels in each speaker and with a reference to average values for Southern U.S. English reported in previous research. The data are discussed in the context of variation in the South, adding Central Louisiana to the linguistic map.
A diffraction based acoustic single pixel imager
Authors: Rogers Jeffrey S. , Rohde Charles , Smith David , Naify Christina J. , Orris Gregory
Published: November 2017

We present a method for localizing an acoustic source with a single, omni-directional receiver paired with shaped aperture screens that allow for a spatially diverse set of measurements. Traditionally this is accomplished by patterning the screen with a series of sub-wavelength openings that allow the acoustic transmission an otherwise sound opaque material. Here we consider screens that have openings on the order of an acoustic wavelength or larger and incorporate a diffraction model into the single pixel imaging framework to account for these larger openings. The method is demonstrated on experimental data taken in air and an analysis of the error as a function of receiver position is presented. [This work was supported by ONR.]
Acoustic characterization of silica aerogel clamped plates for perfect absorption purpose
Authors: Geslain Alan , Romero-Garcìa Vicente , Groby Jean-Philippe , Cervera Francisco , Sanchez-Dehesa Jose
Published: November 2017

Silica aerogel has been widely studied as bulk material for its extremely low density and thermal conductivity. Plates or membranes made of this extremely soft materials exhibits interesting properties for sound absorption. A novel signal processing method for the characterization of an acoustic metamaterial made of silica aerogel clamped plates is presented. The acoustic impedance of a silica aerogel clamped plate is derived from the elastic theory for the flexural waves, while the transfer matrix method is used to model reflection and transmission coefficients of a single plate. Experimental results are obtained by using an acoustic impedance tube. The difference between the measured and modeled reflexion and transmission coefficients is minimized under constraints to recover the acoustic parameters of the silica aerogel plate. Once the properties of the silica aerogel plate are obtained, the perfect absorption condition is derived by studying the reflection coefficient of a aerogel plate rigidly backed with a cavity in the complex frequency domain. Reflection measurements with a varying cavity length from 1 mm to 65 mm are performed to valid the perfect absorption condition. It is found that the use of silica aerogel plate exhibit perfect absorption condition for several configurations.
Breaking the fundamental limit of space-coiling metamaterial: Toward simultaneous phase and amplitude modulation
Authors: Ghaffarivardavagh Reza , Nikolajczyk Jacob , Anderson Stephan , Zhang Xin
Published: November 2017

Acoustic metasurfaces represent a family of planar, wavefront-shaping devices garnering increasing attention due to their capacity for novel acoustic wave manipulation. Despite the successful demonstration of phase engineering using metasurfaces, amplitude modulation remains overlooked. This work explores the feasibility of simultaneous phase and amplitude modulation using space-coiling metamaterials. In the case of conventional space-coiling metamaterials, we observed a fundamental bound on the transmission coefficient, which precludes full wavefront manipulation. Herein, we present a novel class of metasurfaces featuring a modified space-coiling structure and enabling full acoustic control with simultaneous phase and amplitude modulation. The functionality of this class of metasurfaces, featuring a gradient in channel spacing, has been theoretically and numerically investigated and an equivalent model simplifying the structural behavior is presented. Furthermore, a metasurface featuring this novel geometry has been designed and its functionality in modifying acoustic radiation patterns simulated. The class of acoustic metasurface demonstrated in this work provides a new design methodology enabling complete acoustic wave manipulation, which may find utility in a range of applications including biomedical imaging, acoustic communication and non-destructive testing.
The use of acoustic resonators for characterization of underwater acoustic metamaterials
Authors: Wilson Preston S. , Haberman Michael R.
Published: November 2017

The characterization of acoustic metamaterials used in underwater applications at low frequencies (below a few kilohertz) is complicated by the associated long wavelengths (1 m and greater), which render free field methods impractical for a range of frequencies of significant interest. One approach used to address this issue is the water-filled acoustic resonator. The key benefit is that a resonator tube with a length of as little as one half wavelength can be used for material characterization, compared to free-field techniques, which require a spatial extent of several wavelengths in two or more dimensions. Another benefit is that sample size can be orders of magnitude smaller when using a resonator. These benefits are enabling, but come at the expense of designing a system to overcome the fact that practical tube materials such as steel or glass cannot be considered rigid when water-filled. Another caveat is that an appropriate model is required to relate the observed resonance frequencies to the acoustic properties of interest. An overview of resonator-related measurement techniques will be presented, along with recent efforts to apply these techniques to the measurement of underwater acoustic metamaterial properties. [Work supported by ONR.]
Underwater ship noise pattern detection and identification
Authors: Berdnikova Julia , Klauson Aleksander , Mustonen Mirko , Tommingas Mihkel
Published: November 2017

The anthropogenic underwater noise event could be identified by spectral analysis and acoustic pattern pre-classification of previously measured noise sources. This paper discusses real-time applicable methods for separation of purely natural noise recordings when ships are absent from the data polluted by the ship noise. The natural noise periods are used for the statistical modeling of underwater channel environment and relative levels of marine ambient noise (Wenz curves). The anthropogenic noise periods allow us to identify the noise sources. Moreover, most of the ship identification methods require spectrum component processing and pre-determined ship classification, which could be based on this automatic separation results. The correlational and multiple criteria detection methods compared with cyclostationary feature detection and widely used energy detection. False alarm and misclassification minimization could be achieved by multiple sensor data fusion: weather and Automatic Identification System (AIS). The measured data were collected near the seafloor with an autonomous long-term passive acoustic recorder and were combined with ship passage information from the AIS. Three years of measurements include multiple individual ship observations with different speeds and directions. Analysis of the experimental results emphasizes the importance of pre-classification, especially in multiple target cases.
Resonant subwavelength acoustic panels with air inclusions for abatement of noise from underwater machinery and remotely operated vehicles
Authors: Cushing Colby W. , Lee Kevin M. , McNeese Andrew R. , Haberman Michael R. , Wilson Preston S.
Published: November 2017

Deeply subwavelength thickness metamaterial panels consisting of encapsulated cylindrical air cavities cut from elastic plates were recently shown to provide broadband, low-frequency underwater noise suppression for frequencies above the resonance frequency of the cavity [J. Acoust. Soc. Am. 138, EL245–EL257 (2015)]. The present work extends previous findings to investigate noise suppression applications associated with underwater machinery and remotely operated vehicles (ROVs). Air inclusions in the panels were sized for maximum attenuation of the frequency spectrum of the ROV and radiated pressure amplitude reduction as a function of frequency and void fraction was determined. To do this, panels were initially secured around an omnidirectional projector in a single discontinuous layer and the panel surface area was varied to quantify the effect of panel air volume fraction on the radiated noise level. Panels were then sized and arranged around an ROV and the measurements were repeated. Results will be presented and compared to an effective medium model. The system has proven to be a simple way to provide significant noise reduction for machinery and ROV-related noise which is of interest for shallow water applications. [Work supported by the US Navy Office of Naval Research.]
A brief history of the multi-use Theater form
Authors: Glosemeyer Petrone Robin S.
Published: November 2017

Multi-use theatres provide communities with a venue to accommodate almost any performance type that requires a stage. The advent of structural steel, mechanical ventilation, and amplifications systems are a few advances of the late nineteenth and early twentieth centuries that have given shape to the multi-purpose theater; how have they shaped the form we see today?
Effects of variable acoustic elements on the spatial sound field in multipurpose venues
Authors: Vigeant Michelle C. , Neal Matthew T. , Dick David A.
Published: November 2017

The design of multipurpose venues typically includes variable acoustic elements which adjust the acoustics of the space to support the intended use. The most common approach to vary the acoustics of a venue is to use variable absorption, often in the form of heavy drapery and/or acoustic felt banners. These elements are often characterized by changes in reverberation time, but their position also impacts the spatial distribution of room energy. In order to study the effects of variable acoustic elements on the three-dimensional sound field at specific audience locations, spatial impulse response measurements were taken in a number of venues using a 32-element spherical microphone array. The venues ranged from a small recital hall of 400 seats to a typical multipurpose hall with 1300 seats to a 2500-seat concert hall with variable acoustics. Beamforming techniques were used to analyze the effects of the variable acoustic elements on the spatial and temporal distribution of sound energy at several receiver locations in each venue. The sound fields in these venues will be compared to those measured in dedicated concert halls, which have been measured for recent work on the topic of listener envelopment. [Work supported by NSF Award 1302741.]
Selectivity of bat midbrain neurons to stimulus elements embedded in natural echolocation sequences
Authors: Macias Silvio , Luo Jinhong , Moss Cynthia F.
Published: November 2017

We investigated response selectivity of single neurons in the inferior colliculus (IC) of the big brown bat, Eptesicus fuscus, to acoustic elements embedded in the natural temporal patterning of dynamic frequency modulated (FM) echolocation sequences. Acoustic stimuli consisted of species-specific sonar sequences, with natural dynamic spectro-temporal features, containing both bat-emitted FM pulses and echoes from a moving target. Roughly 50% of sampled IC neurons showed responses to a restricted subset of stimulus elements in the natural sonar sequence and selectivity to the time delay between pulses and echoes, the bat’s cue for target distance. Importantly, response selectivity emerged only when stimulus elements were embedded in natural sequences and was absent when the same neurons were stimulated with isolated pulse-echo pairs presented randomly at 300 ms stimulus intervals. These data provide compelling evidence that natural and dynamic sound sequences are necessary to evoke selectivity to pulse-echo delay in midbrain neurons of an FM bat. Our findings suggest that the FM bat’s fine temporal control of pulse interval during insect pursuit contributes to neuronal selectivity that can serve to sharpen acoustic imaging by sonar.
Impact of organic matter on the physical and dynamic properties of marine mud
Authors: Bennett Richard H. , Hulbert Matthew H. , Meredith Roger
Published: November 2017

The physical and dynamic properties of marine mud are a function of the interaction of clay fabric, organic matter (OM), and seawater physico-chemistry, and, when present, free gas. OM is the focus of this presentation and is a determinant of several properties in mud deposits including (1) free water available versus total water content in clay fabric pore space as a result of (2) OM seawater hydration, (3) reduction of permeability by volumetric contribution of hydrated OM in pore space, (4) OM density reduction by seawater hydration versus dry OM density, (5) dynamic behavior by physico-chemical attachment of OM to clay particles in potential energy fields created by the clay fabric signatures (edge-to-face, edge-to-edge, and offset face-to-face) in seawater, (6) high percentages of OM (TOC >2%) result in a high degree of compressibility at considerably lower stress compared to mud deposits with <2%TOC. Measurement and characterization of OM, previously often neglected, is expected to provide new significant insights and understanding of marine mud physical and dynamic properties and contribute to more reliable research data for scientists and engineers. Handling and storage methods used for mud samples containing OM are critical for accurate results.
Variations in ultrasonic transmission behavior along seagrass leaf blades
Authors: Johnson Jay R. , Hermand Jean-Pierre , Wilson Preston S.
Published: November 2017

Seagrass is a complex multi-phase material, and an effective method for connecting acoustic propagation through seagrass meadows to internal or external characteristics of the seagrass would be beneficial for acoustic remote sensing applications. To investigate some of these connections, ultrasonic (1, 2.25, and 5 MHz) time-of-flight measurements through individual leaf blades of the endemic Mediterranean seagrasses Posidonia oceanicaand Cymodocea nodosa are presented. Acoustic measurements were made at multiple points along the leaf blades and the sound speed and signal attenuation varied significantly within a single blade depending on measurement location. The measured acoustic variations are compared to external blade features such as discoloration, epiphyte coverage, and thickness. Microscopy images of blade cross-sections each taken at each acoustic measurement location are used to compare the void fraction to acoustic behavior. [Work supported by ONR, ONR Global.]
Measurements of underwater sound radiated from an offshore wind turbine
Authors: Miller James H , Potty Gopu R. , Lin Ying-Tsong , Newhall Arthur , Vigness-Raposa Kathleen J. , Giard Jennifer , Mason Tim
Published: November 2017

Underwater acoustic and geophysical systems were deployed to monitor the operation of the Block Island Wind Farm (BIWF). The BIWF consists of five GE Haliade 150-6MW wind turbines each with 150 m diameter blades. The five wind turbines were laid out about 1 km apart in a southwest-to-northeast arc. Each turbine is equipped with a direct drive permanent magnet generator, with no gearbox coupled to the generator. These turbines are variable speed and have independent pitch control by blade. The equipment used to monitor the BIWF operation consisted of a towed array of eight hydrophones, two VLAs with four hydrophones each and a fixed sensor package for measuring particle velocity. This sensor package consists of a three-axis geophone on the seabed and a tetrahedral array of four hydrophones at 1 m from the bottom. Additionally, an acoustic vector sensor was deployed in mid-water. During operations in December 2016, an acoustic signal was detected by the tetrahedral array of hydrophones at a position 50 meters west of the southwestern-most turbine. The frequency of this signal was approximately 72 Hz and the rms sound pressure level was about 100 dB re 1 micropascal. [Work supported by Bureau of Ocean Energy Management (BOEM).]
Revisiting the South Australian Environment Protection Authority 2013 Waterloo study using the Schomer principle
Authors: Morris Mary L. , Cooper Steven E.
Published: November 2017

In 2013, the South Australian Environment Protection Authority conducted a 10 week study in relation to noise complaints at the Waterloo wind farm in the Mid North of South Australia. The study involved the use of diaries by 28 households located around the wind farm and noise loggers at 6 dwellings. In analyzing the residents' diaries, the Environment Protection Authority focussed on “noise” events and disregarded comments or observations by the residents which related to other forms of disturbance such as sensation. In the light of the Schomer principle presented in the 2017 ASA meeting in Boston, the 2013 Waterloo study data has been revisited to include an examination of the Power Output and WAV files associated with periods where residents have reported high levels of disturbance.
Startle reflex and sensitisation—How are these biological phenomena relevant to wind turbine noise exposure?
Authors: Laurie Sarah E. , Cooper Steven E. , Thorne Robert
Published: November 2017

Recent laboratory and field research has identified strong amplitude modulation as a trigger for sleep disturbance via acute physiological stress events. Reported, observed, and objectively recorded sudden increases in heart rate as part of a “flight fight response” during both day and night time noise exposure suggests that direct stimulation of the sympathetic nervous system via the startle reflex response may be involved. Mammalian field research has demonstrated that repeated elicitation of the acoustic startle reflex leads to observed sensitisation. Sensitization is also observed in Individuals chronically exposed to amplitude modulated industrial noise from sources including wind turbines. Relevant existing scientific literature, and examples of these events will be discussed.