bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent progress in study of dynamically responsive materials with tailorable microstructural geometric nonlinearities
Authors: Boechler Nicholas
Published: November 2019

It is known that strongly nonlinear materials exhibit rich acoustic behavior. Studies of such materials have hitherto been conducted on disparate material systems that leverage either intrinsic material nonlinearities (which could also be thought as geometric in origin depending on the scales considered) or microstructural geometric nonlinearities. While the latter group has been shown to be tunable to a limited extent, the capacity to freely transition between types of nonlinearity has remained out of grasp. In this talk, I will provide an overview of our group's recent work to use topology optimization algorithms to construct periodic microstructure geometries that have specified nonlinear constitutive responses, along with our exploration of elastic wave propagation within such materials.
Immersive boundary conditions for meta-material experimentation
Authors: van Manen Dirk-Jan , Moleron Miguel , Thomsen Henrik R. , Börsing Nele , Becker Theodor S. , Haberman Michael R. , Robertsson Johan O.
Published: November 2019

In immersive experimentation, a physical experimentation domain is immersed in a numerical simulation such that waves propagate seamlessly from the physical domain into the numerical simulation and vice-versa. The interaction, governed by a novel immersive boundary condition (IBC), takes place in real-time using hundreds of sources and sensors surrounding the medium connected through a low-latency acquisition, compute and control system. IBCs are currently being realized for acoustic and elastic waves. The ability to impose arbitrary IBCs on an experimentation domain presents unique opportunities for research into novel phononic and parity-time symmetric (PTS) meta-materials. We first show how IBCs can be used to realize phononic materials with arbitrary inclusions by imposing 1-D, 2-D, or 3-D periodic conditions on the boundaries of the experimentation domain. Only one or few unit cells have to be constructed to physically create a complete phononic crystal and reproduce its properties if assumed a component of an infinite periodic lattice. Second, we show how IBCs can be used to implement the gain component of a PTS medium. Since the gain is implemented in the numerical simulation it can be arbitrarily adjusted to exactly balance the experimentally realized loss. Numerical validations and initial experimental results will be presented.
Extended-reacting liners in time-domain simulations for broadband attenuation with flow
Authors: Alomar Antoni I. , Dragna Didier , Galland Marie-Annick
Published: November 2019

The modeling and optimization of acoustic liners under grazing flow is an on-going research topic with applications in the aerospace, automotive and railway industries. Recently, the push for next generation airliners and low-noise ventilation systems further increase the need for innovative configurations with improved broadband performance, and with limited size. Porous materials and metamaterials are good candidates to achieve these goals. In this work we propose a time-domain numerical modeling of extended reacting liners using an effective medium approach, which allows to characterize complex media such as porous materials and metamaterials through their effective density and compressibility. The linearized Euler equations are solved in the time domain using efficient high-order finite-difference schemes. The calculation of the convolution integrals is avoided through the auxiliary differential equation method. After a validation of the numerical methodology in a 1-D case, we will present the results for various 2-D configurations, with special attention to the impact of flow. A number of experiments in a Kundt’s tube and in a wind tunnel at the Ecole Centrale de Lyon are also under way to test the model predictions.
Vowel production in children with myotonic dystrophy: A lip-tube perturbation study
Authors: Menard Lucie , Trudeau-Fisette Pamela , Uribe Cristina , Vidou Camille
Published: November 2019

Myotonic dystrophy, a neurodegenerative disease that causes muscle weakness and difficulties in muscle relaxation after contraction, frequently affects orofacial articulatory dynamics leading to decreased speech intelligibility, particularly in children. We aimed to investigate the effects of myotonic dystrophy on sensorimotor relationships in children’s speech through a study of compensations for a lip-tube perturbation. We recruited fourteen 6- to 14-year-old French-speaking children diagnosed with myotonic dystrophy and 14 aged-matched typically developing children. They were asked to produce repetitions of the vowel /u/ with and without a 15-mm-diameter tube inserted between the lips. A synchronized ultrasound, Optotrak motion tracking system, and audio recording system was used to track lip and jaw displacement as well as tongue shape and position. Separate analyses were conducted on the first (F1), the second formant (F2), and the fundamental frequency (F0). Results revealed a significant main effect of group and an interaction between group and condition. Perceptual ratings of the produced vowels suggest that children with myotonic dystrophy rely more on auditory feedback than their typically developing peers. Together, results suggest that auditory feedback plays an important role in speech compensation, especially when the production system is impaired.
The role of auditory feedback in learning speech of second languages
Authors: Tian Xing , Liu Xiaoluan
Published: November 2019

Learning to speak requires coordination between auditory and motor systems. Motor programs need to be fine-tuned based on goals and feedback. The motor-tuning process includes establishing the sensory-to-motor transformation (generate motor codes from articulation) and motor-to-sensory transformation (generate predictions for speech control). In this study, we investigated the relations among the three factors (feedback, goals, and predictions) in speech production in the context of second language learning. Adult Mandarin speakers were asked to learn non-native vowels: /ø/ and /ɵ/—the former being less similar than the latter to Mandarin vowels, in feedback available or feedback masked conditions. We found no improvement in learning when feedback was masked, suggesting that motor-based prediction could not directly compare with goals for adult second language acquisition. Furthermore, feedback helped to learn only when target sounds are distinct from existing sounds in one’s native speech (competition between prediction and goals is minimal). The results suggest prediction and goals may share a similar representational format, which could yield a competing relation in speech learning. The feedback can conditionally overcome such interference between prediction and goals. The study further probed the functional relations among key components (prediction, goals, and feedback) of sensorimotor integration in speech production and learning.
The use of an acoustic quiet zone as an active acoustic cloaking system
Authors: House Charlie , Cheer Jordan , Daley Stephen
Published: November 2019

The use of active control to acoustically cloak an object has been demonstrated previously, and is effective if the scattered component of the pressure field can be measured and directly minimised. In practice, this is non-trivial as a pressure sensor in the sound-field will detect the superposition of the incident and scattered pressures. An alternative approach is presented here which uses the control sources to generate a zone of quiet around the scattering object, with a constraint on their exterior radiation. This reduces the incident acoustic pressure on the object and thus the acoustic scattering. In this case, real-time measurements of scattered pressure or detailed geometrical knowledge of the scattering object are not required. The performance of the proposed acoustic cloaking strategy is assessed using simulated data of a rigid spherical scattering object, using a practical arrangement of control sources and error sensors. The same arrangement of sources and sensors is also used to directly minimise the scattered sound field
Active control of plane waves: Transmission, reflection, absorption and steering
Authors: Cheer Jordan
Published: November 2019

Active control of an incident acoustic wave using an array of secondary source has been extensively investigated. In general, the objective is to attenuate the propagating wave so as to generate a space with a reduced sound pressure level. However, there are a variety of applications where more flexible manipulation of the acoustic wave propagation is required. For example, in architectural acoustics it may be desirable to achieve a particular level of absorption rather than total cancellation of the acoustic wave. This paper presents an investigation into the use of an array of secondary sources to control the transmission, reflection, absorption and steering of an incident plane wave. A formulation is presented that enables the secondary sources to be driven to achieve the desired levels of transmission, reflection and absorption, as well as control over the angle of wave propagation. The requirements in terms of the secondary sources, error sensors and reference sensors are discussed and the physical limits on the control performance are evaluated.
Line-scan imaging of monostatic scattering by a sphere near a flat interface: Identification of direct, indirect, and multiple-scattering paths
Authors: Fortuner Auberry R. , Marston Philip L.
Published: November 2019

Quasi-holographic vertical scans of monostatic scattering give an image in cross-range and time that separates and focuses the different scattering contributions. The scattering of a sphere near a flatinterface is modified by reflections at the interface that are focused in the image at locations depending on the target depth and size. Labroratory experiment was performed in which the monostatic scattering from a soft spherical target near a free-surface was recorded along a vertical line scan. A geometric model describes the contributing paths. The 1st order single-scattering and 2nd and higher-order multiple-scatterings are identified by their location in the quasi-holographic image. The reversibility of the image processing allows individual echoes to be isolated, and this was done to compare in the time and frequency domain the direct specular reflection with the multiple-scattering echoes. The experiment was repeated for various target depths and the dependence of multiple-scattering echo amplitudes with target depth was examined. Finally, a comparison is made between this case and that of scattering from two adjacent targets from a similar line scan and the resulting quasi-holographic image examined elsewhere [D. S. Plotnick and P. L. Marston, in EUSAR 2016 Proceedings]. [Work supported by the Office of Naval Research.]
Measured surface and bottom reflection loss and scattering on the Chukchi Shelf observed during the 2016–2017 Canada Basin Acoustic Propagation Experiment
Authors: Pecknold Sean , Binder Carolyn M. , Badiey Mohsen , Sagers Jason D. , Ballard Megan S. , Turgut Altan
Published: November 2019

During the 2016–2017 Canada Basin Acoustic Propagation Experiment (CANAPE), acoustic transmissions were recorded from both deep- and shallow-water sources on a set of moored receivers, over the course of nearly one year, in ice-covered and open water conditions. One of the source-receiver geometries included LFM transmissions of 4000–1500 Hz and 1100–700 Hz recorded on an eight-element volumetric array at a distance of approximately 400 m. Surface, bottom, and sub-bottom reflections are observed in the data and are used to infer ice and sediment geo-acoustic properties. Some observations about bistatic scattering are also made.
Passive detection on a distributed network using information geometry
Authors: Brooker Daniel J. , Finette Steven I. , Mignerey Peter C.
Published: November 2019

Using data from the recent “Distributed Network Consensus” (DSNCON19) experiment several aspects of information geometric source detection are tested. In this experiment, acoustic data were collected on seven spatially separated bottom mounted arrays in a “truss” configuration approximately 60 NM off the coast of New Jersey using towed and autonomous CW sources. Recent proposals for new detectors based on the averaging of covariances matrices from a single array according to principles of Riemannian geometry are tested against conventional passive detection schemes. In addition, new information-geometric passive detectors are developed for the distributed network of arrays. The possibility of source localization using the network is also considered. [Work supported by the Office of Naval Research.]
Low to mid frequency whale noise compared to ambient noise
Authors: Lani Shane W.
Published: November 2019

While the majority of ocean noise in the low and mid frequency range originates from the surface (shipping, wind wave noise), biologics are the predominant source of noise originating below the surface. Of the biologics, whales are one of the loudest and most frequent producers of vocalizations in the LF and MF bands. Their songs and clicks can be as loud as 236 dB re 1 μPa at 1 m and range in frequency from 10 Hz to well above 10 kHz. For a given frequency band, the ambient noise (excluding biologics) is typically greater than the cumulative effect of all contributing whales; however, as larger hydrophone arrays are built with increasing amounts of array gain this is no longer always the case. This work explores various spatial densities and source pressure levels (SPL) of whales to determine when a collection of whales becomes the dominant noise source on an array.
Acoustic simulation in an orchestra rehearsal room using BRASS software
Authors: Fagerlande Guilherme C. , Torres Julio Cesar B. , Niemeyer Maria Lygia A.
Published: November 2019

The Music School of the Federal University of Rio de Janeiro is located in a heritage-listed building, due to the historical and architectural relevance. Acoustic problems were related to the musicians in the orchestra rehearsal room, such as high reverberation time on certain frequencies and insufficient insulation. The aim of this paper is to analyse the space of the rehearsal room through measurements and to propose corrections through simulations using BRASS (Brazilian Room Acoustic Simulator), a software designed by the Polytechnic School of UFRJ, to achieve acoustic adequacy. The methods used are measurements of mono and binaural impulsive responses in various positions, computational modeling, simulation verification by comparison with acoustic parameters (T60, EDT, CT, C80, D50, etc), and proposition of architectural corrections and improvements in the room with subjective evaluation by auralization for the musicians. The results show the importance of the acoustic simulation method in the design process of music rehearsal rooms, in order to obtain efficient solutions for the use, besides being able to reproduce the room´s sound with auralization, and respecting its original architectonical characteristics.
Investigating fine scale frequency characteristics of Northeast Pacific blue whale B calls
Authors: Carbaugh-Rutland Alexander W. , Favilla Arina , Širović Ana
Published: November 2019

Passive acoustic monitoring is an effective tool for delineating population structure of blue whales (Balaenoptera musculus). Globally, there are at least nine regionally distinct blue whale songs, with at least two distinct groups within the North Pacific Ocean: the Northeast Pacific (NEP) and central or western Pacific populations. Investigation of the fine-scale frequency characteristics of the NEP blue whale song B unit was conducted from passive acoustic data collected between 2010 and 2013. Data were collected at two low latitude, putative breeding sites at Palmyra Atoll and the Hawaiian Islands and three higher latitude, feeding locations: off southern California, off Washington state, and in the Gulf of Alaska. Frequency measurements were extracted along the entire contour of B calls using a custom feature extraction tool in MATLAB. Data from these two different geographic and life-stage regions were compared to investigate possible fine-scale song separation within the larger region. At least two different variants of B unit were found and their geographic and temporal occurrence will be discussed.
Spatiotemporal distribution and population structure of sperm whales in the Eastern North Pacific
Authors: Posdaljian Natalie , Solsona Berga Alba , Baumann-Pickering Simone , Frasier Kaitlin E. , Hildebrand John
Published: November 2019

Sperm whales are a sexually dimorphic, cosmopolitan species, with a stratified distribution. Generally, males grow larger and travel to higher latitudes, while mature females and immature whales form social units thought to be more common in tropical and temperate regions. Little is known about their migration, especially by males for mating. Here, we outline an approach to detect presence of sperm whales echolocation clicks and the spatiotemporal distribution of sexes at 12 sites along the eastern North Pacific by using click characteristics as a proxy to estimate acoustic total body length and as an indicator for sex. Sperm whales were detected at all sites, including continental slope, deep abyssal, and seamount habitats. Some recording sites showed seasonal patterns potentially linked to the demographic composition of the population, especially males moving between temperate and high latitude regions. We also found females frequenting sites in the high-latitude habitats of the Gulf of Alaska and the Bering Sea Aleutian Islands, where they have been rarely documented since whaling. Our analysis improves the understanding of the spatiotemporal distribution and population structure of sperm whales which is essential for efficiently estimating densities to inform appropriate management and conservation measures.
Mike Buckinghams’s contributions to sub-Arctic acoustics
Authors: Diachok Orest
Published: November 2019

Mike initiated his research in ocean acoustics and his love affair with aircraft during his tenure with the Royal Aerospace Establishment (RAE). Between 1984 and 1990, he led the RAE effort to characterize and model the ambient noise field in the sub-Arctic (Buckingham, 1987, 1990, and 1994). Mike deployed and monitored sonobuoys from aircraft at several distances from the ice edge. His experiment confirmed Diachok and Winokur’s (1974) observations of a peak in ambient noise levels at the ice edge due to the interaction of ocean waves with sea ice. More importantly, Mike discovered an “enigmatic” intermittent source of high ambient noise levels, which peaked at about 20 Hz, at or near the Greenland glacier. He concluded that the source mechanism was associated with the glacier. In 1990, the Scripps Institution of Oceanography offered Mike a position, in part because of his stimulating pre-offer lecture on ambient noise in the sub-Arctic. As a result of increased melting of glaciers, noise generation at the glacier ocean boundary has become a “hot” research topic. The recent well-designed interdisciplinary experiment of Glowacki et al. (2015) revealed that calving and crashing of glacier blocks into the sea are the most likely cause of Mike’s enigmatic noise.
Quantitative evaluation of liver diseases using multi-PDF models
Authors: Yamaguchi Tadashi
Published: November 2019

We have proposed the triple Rayleigh probability density function (TR-PDF) model as the in vivo QUS method of liver fibrosis. Additionally, the double Nakagami probability density function (DN-PDF) model was proposed to evaluate the amount and distribution condition of fat droplets in the fatty-liver livers. The DN-PDF permitted to detect early and moderate fatty livers in previous ex vivo studies with over 15 MHz ultrasound. In our recent studies, we are examining clinical data to determine whether two multi-PDF models can evaluate each disease even at low frequencies. In this talk, the results of in vivo studies for liver fibrosis and fatty liver will be introduced.
Ultrafast ultrasound breast scanning for improved image quality and functional information in 3-D
Authors: Hendriks Gijs , Chen Chuan , Hansen Hendrik , de Korte Chris L.
Published: November 2019

With an automated breast volume scanner (ABVS), a volumetric breast image can be constructed. Clinical studies show high sensitivity but also high recall-rates due to the detection of many lesions of uncertain malignant potential. It is known that breast lesions have different mechanical properties with respect to its surrounding tissue. Consequently, imaging the biomechanics of a breast might improve diagnosis in this disease. First, we improved the image quality by taking full advantage of the ultrafast acquisition and by applying dedicated signal processing techniques. Next, by imaging biomechanics we increased the specificity since compared to benign lesions, malignant lesions are often stiffer, and more grown into the surrounding tissue (firmly bonded). We extended conventional 2-D strain imaging to full 3-D (shear) strain imaging by combining automated breast volume scanning with ultrafast plane wave imaging (10 000 frames/s). Validation studies in breast phantoms revealed that lesions could be differentiated based on strain and shear strain imaging. Decreased strain values were found in stiff lesions and firmly bonded lesions demonstrated low shear strain values. Initial acquisitions in patients demonstrated decreasing strain values with increasing severity of the disease. Additionally, we developed an ultrasensitive 3-D Doppler method to detect neo-vascularization that might be present around malignant lesions. In conclusion, imaging the biomechanical properties in 3-D improves diagnosis breast cancer.
Commercializing Piezo-MEMS electroacoustic sensors
Authors: Grosh Karl
Published: November 2019

Microphones are ubiquitous, appearing in consumer electronic devices like mobile phones, smart speakers, and voice activated appliances. In this talk, one path taken to transitioning a particular University-discovered technology, a piezoelectric micro-electro-mechanical-systems microphone, from a research project to a venture backed company (Vesper Technologies) will be described. The low dielectric loss of aluminum nitride (AlN) combined with its elastic and piezoelectric properties proved to be the enabling material for the design of electroacoustic sensors with low input referred noise for in-air acoustic sensing. The availability of industrial quality AlN deposition tools has made the manufacture of these devices at scale for the consumer electronics industry possible. Designs that mitigate the deleterious effects of variable residual stresses and allow for consistent sensitivity over the wafer (from device to device) are described. The flexibility afforded by MEMS technique has enabled the fabrication of various other sensors and experimental examples of function along with modeling results will be shown for both in-air and underwater devices. The potential advantages of enhanced piezoelectric materials will be presented. Mechanisms for leveraging University, Governmental (Local, State, and Federal), and Equity based funding sources are described.
A study on the effect of the vertical sound field control of the flat panel display speaker on audience
Authors: Lee SungTae , Park Kwanho , Park Hyung Woo
Published: November 2019

Technological improvement in the display industry, the organic light-emitting diode(OLED) panel manufacturer changed the quality of picture and sound improvement. In previous research, we introduced the technology that uses the display panel as a speaker and also to improve the sound quality by improving the vibration characteristics and horizontal acoustic characteristics of an OLED panel. In this study, we analyzed the characteristics of the vertical direction sound of the TV and to consider auditory sense at various distances. When watching TV, unlike normal viewers, the infant and child viewers are too close to the screen. Acoustic transmission using conventional TV allows the reflected sound to propagate from downward. So, near the TV and in a low position, a loud sound is formed. This causes hearing damage at close range and low clarity at long range. The exciter speakers can basically eliminate these disadvantages of the sound field. And, by adaptive control of the sound, it is possible to transmit a clear sound in a wide space by reducing loss due to the distance. This paper introduces the results of the study on the improvement of sound quality through control algorithm and the protection of hearing audiences through sound field analysis.
Mentoring the person: Building on strengths and managing challenges
Authors: Shinn-Cunningham Barbara
Published: November 2019

Mentoring is not about setting up expectations of perfection, but working with each person to help them succeed. Every person, from undergrad to senior professor, has some skills that come naturally, and some that, …well…, do not. This talk will reflect on the fact that good mentoring involves helping each unique person identify both their “super powers”—as well as their weaknesses. Each person has things that they are good at, that they enjoy, and that speak to their values (their super powers). But knowing how to mitigate weaknesses is equally important, whether it is through recruiting a good collaborator to fill in a gap, working to strengthen a particular skill, or simply forging a path where a particular weakness is not critical. Along some paths, perseverance and an ability to see the big picture may be more critical than programming skills or mathematical wizardry; along others, raw intellectual horsepower and an ability to focus may be key, without relying on having to work closely with others. Without naming names, I will provide some examples of how some of my mentees have succeeded by building on their strengths while managing their personal and professional challenges.
Choose the right people and help them realize their worth
Authors: Holland Christy K.
Published: November 2019

Students flock to “good” labs, places where the love of science first strikes. To attract talented people, your lab must be a place that breeds good science and successful trainees. Hallmarks of a wonderful lab include exciting projects, collaborative publications, and students and postdoctoral fellows who have found good jobs. The head of the lab knows how to and is willing to pass along these skills to other members of the lab. Strategies for how to choose your people carefully and how to determine when to hire a technician, lab assistant, student, or postdoctoral fellow will be outlined. Examples of how to determine a candidate’s capability of performing the job, and if the candidate will fit into the existing lab will be discussed.
Reflections of mentoring midshipmen and high school students at the United States Naval Academy—With student recollections
Authors: Santos Emily V. , Haas Katherine A. , Cartron Jenna M. , Korman Murray S.
Published: November 2019

For 38 years, MSK has developed mentoring undergraduate students in the Physics Department. Mentorship is a unique dance, a growing tree—with kind branches embracing any challenge—a give and take enjoyed by both the mentor and mentee. It should be fun—filled with goals to achieve (often wrapped in a research challenge). “Acoustics” and “Underwater Acoustics and Sonar,” courses—inspire projects. Students have presented research at ASA meetings. Some become co-authors on published papers. For 35 years, MSK developed a high school mentorship program at USNA. Rising juniors and seniors may apply. HS mentees start their research on a project that evolves over one or two months working twice a week for 2.5–3 h sessions. Students often continue over the summer. Recently, MSK took HS mentorship students to the ASA Boston Meeting, the 17th ISNA Meeting (Santa Fe 2018), Louisville and Internoise 2019 in Madrid. Three HS seniors at the ISNA conference presented research (published in POMA) on (1) nonlinear acoustic landmine detection with wetted and dry beads [EVS], (2) acoustic levitation and nonlinear sound scattering by a bubble [KAH], and (3) the interaction of two crossed ultrasonic streaming jets [JMC]. Their dedication and insights are highly valued.
Ideas for improving each phase of a mentored research relationship
Authors: Gee Kent L.
Published: November 2019

A challenging part of an academic’s job is developing productive research relationships as a mentor. This paper presents ideas for improving a mentor’s effectiveness at different stages, from student recruiting through the relationship’s redefinition upon graduation. These ideas stem both from personal experiences with undergraduate and graduate students and from a review of relevant literature.
Mentoring with intent, even when you aren’t a student's research advisor
Authors: Russell Daniel A.
Published: November 2019

The roles of mentoring and advising are closely related, but not necessarily equivalent, and the distinction between the two is often blurred. It is most often expected that a student’s research advisor will also be their primary mentor. The research literature exploring how graduate students learn (especially the theory of “Community/Landscapes of Practice”) suggests that most learning happens outside of the classroom, that students need a network of mentors, and that a student’s research advisor should not play all of the mentoring roles for that student. I was quite surprised to receive the 2016 ASA Student Council Mentor Award, because in my current role as a teaching professor at Penn State, I do not advise many graduate students earning their M.S. or Ph.D. who do their research under my direct supervision. However, I do play an active role as a mentor, guiding the academic and professional development of many students in our program. I played a similar role to a large number of undergraduate students at my previous institution. In this talk, I will discuss several ways that faculty can mentor to students who are not their own research advisees.
Learning and teaching acoustics through bubbles
Authors: Wilson Preston S.
Published: November 2019

By a lark, I started my acoustics career as a graduate student studying a single big bubble in the form of the combustive sound source. By at least the luck of being in a certain place at a certain time, I finished my graduate education by studying bubbles in the form of the acoustics of bubbly liquids. It turns out that the subject of bubbles provides an excellent lens through which to learn and teach acoustics. One starts with lumped element approximations which lead to simple harmonic oscillators and resonance. You can study the bubble oscillator as linear system and encounter increasingly complex nonlinear behavior at comparatively low amplitudes. A bubble is a source of sound initially modeled as a simple spherical source and can of course behave as a spherical scatterer. Add one or many bubbles and one can study more complex scattering and propagation that includes dispersion and loss. Along the way one encounters effective medium theories of varying complexity and statistical descriptions of acoustic phenomena. There are also applications that require inference and inverse techniques. You can even apply a model of a single bubble to study the expansion and contraction of the universe. Examples of these including demos and videos will be presented.
Comprehensive experimental characterization of violin vibration and radiation dynamics
Authors: Bissinger George
Published: November 2019

Measuring only violin radiation cannot remove ambiguities in resonance peak identification arising from various minor substructure couplings, or whether the radiation arose from the f-holes or surfaces. Measuring only vibrations gives no clue as to how well each mode radiates or even how the vibrational energy was dissipated. To put these into a structural acoustics milieu, comprehensive measurements of all the violin’s energy loss paths were essential. To accomplish this a wide range of calibrated transducers (accelerometers, multiple microphones, near- and far-field microphone arrays, scanning laser vibrometers) were used in a wide range of experiments: cavity mode analysis using interior microphones; interior gas-exchange; EMA on a violin with and without a soundpost; waterfill experiments on a rigid violin-shaped cavity; automated zero-mass-loading, surface-normal (and 3-D) scanning laser EMA on violins supported in a near-zero-damping support fixture; automated far-field radiation measurements over a sphere in an anechoic chamber; bridge tuning effects; near-field acoustical holography over the f-holes. Each technique had limitations, some severe. Some experiments were “table top”; some required expensive associated facilities like an anechoic chamber. Costs of transducers and power-amplifier-control electronics, computer-based acquisition hardware/software varied dramatically; most operational problems occurred in the computer-based data acquisition/analysis systems.
Experimental characterization of basic violin structural acoustics
Authors: Bissinger George
Published: November 2019

Considering its simple construction the complex material-shape traditional violin, fashioned from nominally orthotropic materials to form a ported, compliant-wall cavity, enjoys a notable scientific complexity, e.g., four separate radiation mechanisms, coupling between the two lowest cavity modes A0 (Helmholtz resonance, ∼275 Hz) and A1 (1st longitudinal “slosh” mode, ∼470 Hz), and between A0 and two 1st corpus bending (B1) modes near 500 Hz. Comprehensive EMA (velocity/force), radiativity (pressure/force) and near-field acoustical holography (f-hole volume flows/force) measurements plus bridge tuning systematics were combined to establish a dual-region structural acoustics model of the violin. In the “deterministic” region the large-volume-change B1 modes drive large, in-phase f-hole volume flows accounting for >50% of B1 radiation and excite A0; oppositely directed upper-bout/lower-bout cavity volume flows excite A1. A wall-driven, dual-Helmholtz resonator network successfully modeled A0 and B1 radiation. In the “statistical” region where the major bridge and plate tuning effects occur, radiation efficiency (averaged-over-sphere radiativity divided by averaged-over-corpus mobility) led to radiation damping and critical frequency. With total damping from mobility fits the radiation/total damping ratio (fraction of vibrational energy radiated) was combined with a parametric model of mobility. Splicing the regions created the “dynamic filter” model of violin radiation.
Electronic speckle pattern interferometry: applications to the structural acoustics of percussion instruments
Authors: Worland Randy
Published: November 2019

Electronic speckle pattern interferometry (ESPI) provides real-time images of operating deflection shapes of acoustically driven structures. This technique is particularly useful in the study of musical percussion instruments containing bars, plates, and membranes. Musically relevant examples involving drumheads and vibraphone bars are described. In addition, a dual-ESPI system that produces simultaneous measurements of two surfaces of an object (e.g., the two heads of a drum) is illustrated. Imaging through water is also shown, as applied to the musical technique in which an orchestral crotale is submerged in water to varying depths. Finally, the interferometer is used to image the confined modes of the “musical saw” when bent into its characteristic “S”-shape. Practical issues of object mounting and image production are discussed.
Estimating propagation and audibility of industrial noise in subnivean polar bear dens
Authors: Owen Megan A. , Pagano Anthony M. , Sheyna Wisdom , Bowles Ann
Published: November 2019

Polar bear (Ursus maritimus) maternal dens are ephemeral and difficult to monitor, so predictive models of noise penetration into dens are needed. Noise propagation into artificial snow dens was monitored from 9 sources typical of industrial activities (2 aircraft, 2 over-tundra tracked vehicles, 4 wheeled on-road vehicles, and humans walking) near Milne Point, Alaska. Dens were built in 4 configurations, 2 depths (100 cm, 70 cm) and 2 closure conditions (closed, open) to model variability in den roof thickness and breeding stage (before, after emergence). An existing polar bear audiogram was used to predict detection probabilities. Levels <200 Hz would be heard poorly; after accounting for hearing, aircraft had ≥75% probability of being detected within dens at distances <1600 m, and ground-based sources at distances <800 m. On average, closed dens reduced noise levels by 15 dB (re 20 μPa) relative to open dens, but there was interaction between den closure and depth. Some sources were likely to be detected farther from dens than expected. The results reinforce the importance of maintaining disturbance buffer zones around polar bear dens.
The effect of transportation noise on sleep and its consequential effect on health
Authors: Solet Jo , Schnitta Bonnie
Published: November 2019

Sleep disruption by noise is a well-known phenomenon that has demonstrated negative health and cognitive impacts. Furthermore, it has now been determined that individuals suffering from certain health conditions, including PTSD and atrial fibrillation, may actually experience enhanced noise sensitivity with additional risks. This paper presents the results of several studies that confirm the importance of addressing transportation noise, over which individuals typically have no control, to protect environments intended for sleep such as hospitals, senior housing facilities, and residences.
Case study review of vibration mitigation for a building foundation isolation using elastic polyurethane bearings
Authors: Scarlett Jessica , Born Alexander C.
Published: November 2019

This abstract addresses a case study review of a new construction mixed-used building located in New York City, New York. The building site was located adjacent to an existing subway tunnel. Measured vibrations from train pass-by events were perceptible and above Federal Transit Administration “Daytime Criteria.” Custom elastic polyurethane bearings were designed to provide vibration and ground-borne noise mitigation according to specified insertion loss values. The elastic bearings were installed at the foundation level along with additional elastic structural components. Post-construction vibration measurements were compared to initial site measurements and theoretical calculations of the implemented solution. Accuracy of the theoretical model to finalized isolated structure were analyzed.
Amplified concert noise modeling with environmental noise software
Authors: Manley David , Horesco Joseph
Published: November 2019

The transformation of an existing park platform stage and 0.5 acre listening lawn into a modern outdoor pavilion and amphitheater with 4 acres listening area presents potentially significant challenges for noise impact changes to the surrounding community. Previous site studies had been completed but new designs and marketing presented using proprietary noise level plots from loudspeaker manufacturers presented new obstacles requiring further study. DLR Group partnered with Acentech to complete additional site noise measurements and CadnaA environmental noise computer modeling of the site with the potential future improvements. Results of the latest modeling are presented, as well as comparison and discussion of the different modeling programs outputs.
Inverse design and deep learning for phononic crystals
Authors: Srivastava Ankit
Published: November 2019

In this talk, I will present some results pertaining to the inverse design of phononic crystals. First, I will consider the design of 3-D phononic crystals exhibiting large omnidirectional bandgaps within the context of topology optimization using the SIMP method. The problem will be presented in the traditional forward-inverse paradigm where the forward solver is a mixed-variational scheme implemented on multiple graphical processing units. The inverse solver is a large scale adjoint based optimization framework with highly efficient vectorized operations for sensitivity calculations. In the second part of the talk, I will consider a deep learning based surrogate model for the forward problem. The neural network architecture is based on convolutional neural networks (CNN) and is trained to predict the phononic eigenvalues of unseen unit cell configurations. I show that a CNN based model easily outperforms traditional neural network architectures such as the multi layer perceptron (MLP) on both efficiency of learning and generalization capabilities. Strong and highly efficient surrogate models such as CNN coupled with topology optimization provide a an important way forward for the inverse design of phononic crystals and metamaterials.
Convolutional neural network driven design optimization of acoustic metamaterial microstructures
Authors: Robeck Corbin , Cipolla Jeffrey , Kelly Alex
Published: November 2019

The design of broadband mechanical metamaterials in the context of acoustics can be driven by the invariance of the wave equation under a set of special coordinate transformations called transformation acoustics. A program of homogenization to design the metamaterial structure can be derived from these transformation functions subject to geometric constraints from the metamaterial’s intended application. The limits of homogenization in a nonperiodic, nonlinear environment however must be accounted for and corrected. This can be done by means of nonlinear manifold interpolation methods, the feedback into which is driven by the scattered wave field in the ambient medium. The feedback is minimized using statistical and machine learning techniques, dictating the final metamaterial structure. The performance of this algorithmic method is compared against a “brute force” optimization approach driven by a convolutional neural network with no transformation of the underlying wave equation.
Effects of interaural phase on the frequency following response
Authors: So Won , Cheng Fan-Yin , Champlin Craig A.
Published: November 2019

The frequency following response (FFR) is generated by periodic auditory stimuli and represents the summed phase-locked activity from the brain. The aim was to examine this neural activity in response to several interaural phase configurations of binaural stimulation. The FFR was recorded from 10 young adults with normal hearing. The stimulus was a 400-Hz tone burst presented at 70 dB SPL. The starting phase of the tone presented to the right ear was always 0 deg while the phase of the tone presented to the left ear varied in 45-deg increments from 0 to 180 deg. The FFR amplitude measured with an interaural phase of 0 deg was not significantly different from amplitudes measured at 45 and 90 deg; however, FFR amplitudes acquired at 135 and 180 deg were significantly lower than the 0-degree condition. The dominant frequency component of the FFR was 400 Hz in all interaural phase conditions except 180 deg. The implications of neural measures of binaural interaction will be discussed.
Altered auditory sampling in infants at risk for dyslexia across the sensitive period of native phoneme learning
Authors: Mittag Maria , Larson Eric , Taulu Samu , Clarke Maggie , Kuhl Patricia
Published: November 2019

Recent research in dyslexia postulates that imprecise representations of phonemes are linked to basic auditory deficits in temporal sampling. Evidence comes from adult readers with dyslexia demonstrating deficits in auditory sampling at several rates of the speech signal including the phoneme rate (>40 Hz). It remains unknown whether such deficits are present in infancy, especially during the “sensitive period” for native phoneme learning (6–12 months). We examined auditory sampling in infants at risk for dyslexia across the period of native phoneme learning. Using magnetoencephalography, we recorded auditory steady-state responses (ASSRs) to white noise that was amplitude-modulated at frequency rates relevant to speech processing in 6- and 12-month-old at-risk and typically developing (TD) infants. Our results show that the two groups differed in hemisphere involvement of ASSRs at the phoneme rate (50–80 Hz): TD infants showed a shift from right-to-left hemisphere processing from 6 to 12 months, whereas at-risk infants showed stronger right-hemisphere processing at 12 than 6 months. This measure predicted words understood at 13 months. Risk for dyslexia is associated with auditory sampling deficits throughout the sensitive period. These deficits may affect future language acquisition.
Serial recall of spectro-temporal patterns under informational masking
Authors: Conroy Christopher , Roverud Elin , Kidd Gerald
Published: November 2019

This study investigated the memory costs associated with informational masking (IM) and the memory benefits associated with its reduction. A serial recall task was used wherein the stimuli to be recalled were random sequences of six possible learned spectro-temporal patterns masked by other random sequences of spectro-temporal patterns. Sequence lengths of 1, 3, and 5 were tested. In all conditions, a target sequence and a masker sequence were assigned to mutually exclusive frequency bands. In the high-IM reference condition, the frequency separation of the two bands was chosen so as to be just discriminable and the onsets of corresponding target and masker patterns roughly overlapped in time. In the comparison conditions, IM was reduced systematically by increasing the frequency separation of the two bands and staggering the onsets of corresponding patterns. When IM was high, recall was poor and memory costs were large. As IM was reduced, recall improved, revealing memory benefits typically not discernable in standard detection, discrimination, or recognition-based studies of IM. Large individual differences were found and a number of observers were unable to perform the task at the pre-established criterion level even after training in unmasked conditions. The interaction between IM and memory will be discussed.
Establishing an audibility sensitivity rule for low-frequency tone complexes in noise
Authors: Rafaelof Menachem , Christian Andrew , Shepherd Kevin P. , Rizzi Stephen A. , Stephenson James H.
Published: November 2019

Predicting the audibility of a sound over ambient noise is an important step to assess its impact on observers. One anticipated need for such predictions is the desire to operate aerial vehicles in urban surroundings close to the public. The increased audibility of a complex set of low-frequency tones due to the recruitment of a number of independent auditory channels has been investigated in this work. Three experiments were carried out to establish a sensitivity rule for these signals. During the main experiment, the masked threshold for signals consisting of one, two, and three tone components (55, 120, and 200 Hz) were measured. As expected, the thresholds identified during this experiment point to an increased sensitivity relative to a single-tone case. However, these increases were greater than similar findings by other researchers at higher frequencies. Two follow-up experiments examined the effect of larger frequency separation between tones and their intermodulation. The findings of these experiments attribute part of the audibility improvement to biased estimation of the thresholds of multitone sounds due to an error in the estimation of thresholds for single tones. Additional details may be found in a forthcoming NASA Technical Memorandum entitled “Audibility of Multiple, Low-Frequency Tonal Signals in Noise.”