bluuebunny/crossref_metadata_2025 huggingface dataset:
Data-driven source localization using shipping sources of opportunity
Authors: Durofchalk Nicholas C. , Jin Jihui , Saha Priyabrata , Romberg Justin , Mukhopadhyay Saibal , Sabra Karim G.
Published: December 2020

Underwater source localization is often achieved with a purely model-based approach such as matched-field processing, which relies on simulated replica-field. However, such approaches only yield reasonable predictions if the complex and dynamic ocean environment is sufficiently known – often a daunting task. Alternatively, it has been suggested that channel impulse responses (CIRs) estimated from measurements of sources of opportunity (such as commercial shipping vessels) can feed a data-driven approach to source localization that forgoes the need for precise model-parameters [Durofchalk et al., JASA 146(4), 2691–2691 (2019)]. In this presentation, vertical line array (VLA) data from the SBCEx16 experiment conducted in the vicinity of shipping lanes in the Santa Barbara channel (580 m depth, downward refracting profile) are first used to a construct a library of estimate CIRs between selected locations along shipping tracks and VLA receivers using ray-based blind deconvolution (RBD) [Byun et al., JASA 141(2), 797–807 (2017)]. Subsequently, this library of data derived CIRs is used to train a machine learning algorithm to localize other surface sources. The average localization error and computational efficiency obtained with this machine learning approach is compared to that of traditional matched field processing techniques.
Localization correction method for underwater sensors network drift with single float-anchor node
Authors: Zhao Chen , Zhou Feng , Qiao Gang
Published: December 2020

Distributed localization method based on wireless sensor networks (WSNs) have been widely used in marine target locating. Main aim of underwater localization is to overcome the influence on acoustic channel and underwater environment to provide a higher accuracy for target exploration and navigation. Unfortunately, affected by the ocean current, sub-anchor nodes in WSNs will drift away from the initial position and led an obvious positioning error for the target. To overcome this difficulty, the paper proposes a novel and efficient method based on one extra float-anchor node (which the precise location is known) to optimize the positioning results. The proposed method consists of three stages: (a) to estimate the location of float-anchor node with sub-anchor nodes; (b) to compare the estimation result and real location of the float-anchor node to calculate the compensation function; (c) to locate the target with sub-anchor nodes and correct the result with compensation function. Simulation experiments clearly show that the proposed method have a significant improvement in the localization accuracy. The paper achieves correction localization method with existed sub-anchor nodes and only one extra float-anchor and obviously improve the positioning accuracy.
Research on detection method of single-beam echo sounder based on equivalent measurement
Authors: ChenHEN Chao
Published: December 2020

In order to detect the accuracy index of the full range of the single-beam echo sounder in the laboratory sink, a detection method based on the equivalent reflection interface of the acoustic signal is proposed. A set of measurement and detection device consisting of underwater acoustic response device, laser rangefinder (standard device) and five-sided muffler pool is also designed. The acoustic signal equivalent interface adopts a DSP-based circuit design. By equivalent simulating a long-distance echo signal with the delay and attenuation of the electrical signal, different equivalent depths are constructed in the anechoic environment. Finally, a data traceability system for a single- beam echo sounder can be established through correspondence formula derivation and data analysis.
Learning architectural acoustics at Penn State with Jiri Tichy 1971 to 1977
Authors: Roy Kenneth P.
Published: December 2020

While studying electrical engineering at the University of Maine, I became aware of the specialize field of “acoustics.” After graduation from UMaine with no specific plan in sight, it occurred to me that graduate studies in architectural acoustic would be of interest. So, I wrote to Leo Beranek to inquire about which schools might be considered for such graduate work. From Leo's list of five schools I applied to two, one of which offered an assistantship, and Penn State which did not. I chose Penn State because of a professor in Architectural Engineering—Jiri Tichy. After the first semester, I was offered a graduate assistantship doing research on small room acoustics directly with Jiri Tichy, and I was his first student to receive an M.S. degree in acoustics through the Dept. of Architectural Engineering in 1973. I changed course along with Jiri as he became the director of the Interdisciplinary program in Acoustics, and I continued with his research assistantship graduating with a Ph.D. in Acoustics in 1977. I retired from a career in research in 2017 having spent my entire life doing what I learned because of Jiri, both in technology and in life.
An overview of mixed-model inversion and its application to the study of traumatic brain injury
Authors: Romano Anthony J. , Szymczak William G.
Published: December 2020

Previously, we introduced Mixed-Model Inversion which utilizes a fusion of Magnetic Resonance Elastography (MRE), Diffusion Tensor Imaging (DTI), and a combination of isotropic and anisotropic inversion algorithms for the evaluation of the viscoelastic stiffness and anisotropy of the human brain. This approach was developed as a non-invasive diagnostic tool for the study of brain health or pathology. The aims of this work are (1) to evaluate the viscoelastic properties of the brains of both healthy controls and patients who present with Traumatic Brain Injury (TBI) and (2) to demonstrate the alterations to the stiffness and anisotropy of healthy brain structures as a result of insult/injury. When compared to healthy controls, there were significant differences in the stiffness as well as the anisotropic models of the white matter in the TBI patients, with alterations in dependence upon the insult/injury experienced. Preliminary studies indicate that this fusion of measurement and analytical modalities can provide metrics, based on differences in material stiffness and anisotropy, for differentiation between healthy controls and TBI patients for diagnostic purposes. [Work supported by Dr. Timothy Bentley, ONR Code 34, Warfighter Protection.]
Recycling data: An annotated marine acoustic data set that is publicly available for use in classifier development and marine mammal research
Authors: Kanes Kristen S.
Published: December 2020

Barkley Canyon is a productive submarine canyon approximately 60 km southwest of Vancouver Island, Canada. The canyon's nutrient flow is affected by multiple regional currents, and draws aggregations of euphausiids, hake, herring, and various marine mammal species. A subset of the acoustic data collected from the 2013–2015 hydrophone deployment on the Barkley Canyon Upper Slope platform of Ocean Networks Canada's North-East Pacific Time-series Undersea Networked Experiments (NEPTUNE) observatory was manually annotated for marine mammal presence to investigate marine mammal habitat use and in support of development of a random forest classifier. This dataset, which is being made publicly available for further use, includes strong-label annotations of phonations from blue whales, fin whales, humpback whales, sperm whales, orcas, Pacific white-sided dolphins, Risso's dolphins, and other delphinids that could not be identified to species. All regional orca communities are represented within the dataset, and phonations are labelled to ecotype and pod level when possible. This dataset could be further used in a number of ways, including classifier development, investigations into habitat use and seasonality, or combining the acoustic data with data collected from co-located oceanographic instruments to investigate links between marine mammal presence and oceanographic conditions.
Burst-pulsed sounds of rough-toothed dolphins (Steno bredanensis) in Southeastern Brazil
Authors: Lima Isabela M. , Barbosa Mariana , Bisi Tatiana , Lailson-Brito José , Azevedo Alexandre
Published: December 2020

Recordings of Steno bredanensis were done in Southeastern Brazilian coast during eleven days between 2013 and 2017. The system consisted of a C54-XRS hydrophone (−165 dB re: 1 V/μPa, 0.009 to 100 kHz) and a Fostex FR-2 digital recorder with a 192 kHz sample rate. Recordings were inspected for burst-pulsed sounds in Adobe audition 1.5 software in a 512 Hann window, 50% overlap. When they were found, the sound was cut to a new file of 2-s window, and a butterworth high-pass filter was used when necessary. A burst-pulse sound was considered for analysis when its pulses were correctly and clearly identified in the Sound Ruler software, which was used to obtain the acoustic parameters (512 Hann window, 50% overlap). Thirty-one burst pulsed sounds were analyzed. The mean number of pulses per burst-pulse was 52 ± 44 (varying between 6 and 224), mean inter-pulse interval was 5.1 ± 1.9 ms (varying between 2.4 and 8.4 ms), mean burst-pulse duration was 0.27 ± 0.23 s (varying between 0.04 and 1.1s), and mean peak frequency was 26.1 ± 11.3 kHz (varying between 7.0 and 64.7 kHz). Although preliminary, these results show a first characterization of the burst-pulsed sounds of this species.
More than song and calls: New repetitive tones for humpback whales in the breeding area of Colombia
Authors: Palanca Mar , Walker Lisa , Duque Esteban , Nichols Ross , Seger Kerri D. , Sharpe Fred , Friedlaender Ari , Perazio Christina E.
Published: December 2020

The vocal repertoire of humpback whales (Megaptera novaeangliae) consist of long and complex songs and social calls. Songs are characterized by their cyclical and predictable structure in form of units, phrases, and themes. On the contrary, social calls are less predictable and generally short bursts of vocalizations that mainly occur during inter or intragroup interactions. During monitoring activities of reproductive stock G in Bahía Solano (Breeding ground, Colombia), a series of undescribed vocalizations were recorded, which we called repetitive tones. These are loud, frequency modulated (between 280 and 770 Hz), quickly repeated vocalizations. They are shorter than one second and have short inter-call intervals (from 0.7 to 1.0s). They do not follow the pattern of either vocal category established in the species' repertoire. Here we discuss the occurrence of such vocalizations as a result of acoustic and behavioral plasticity of cetaceans. We explore vocal mimicry, song crystallization, or the documentation of a new single-unit song type as possible scenarios to understand the potential function(s) of these tones. Framing acoustic behavior in the cognitive and adaptive capacity of cetaceans argues for a third vocal repertoire category that could serve as the basis for contextualizing new behavioral displays.
Numerical evaluation of a fractional calculus model for the spatial impulse response of a circular piston
Authors: Murray Drew A. , McGough Robert J.
Published: December 2020

In lossless media, exact analytical expressions for the spatial impulse response describe the effect of diffraction in the time domain for several specific transducer shapes. At present, no exact analytical expressions are available for lossy media, so numerical evaluation of the spatial impulse response is required. For attenuation that follows a power law, the spatial impulse response is numerically evaluated by superposing contributions from time-domain Green's functions for the Power Law Wave Equation, which is a fractional calculus model for power law attenuation. To demonstrate examples of lossy spatial impulse responses obtained with these time-domain Green's functions, which are expressed in terms of maximally skewed stable densities, numerical results are computed for a circular transducer using different attenuation values and compared with the analytical result for a lossless medium. The results show that the numerically computed spatial impulse response for a lossy medium converges to the analytical result evaluated in a lossless medium as the value of the attenuation constant decreases. As the attenuation constant grows larger, the temporal extent increases, and the sharp edges are replaced by increasingly smooth curves, as observed in numerical evaluations of the lossy spatial impulse response evaluated in multiple locations.
The link between internal microbubbles in kidney stones and the Doppler twinkling artifact
Authors: Rokni Eric , Zinck Scott , Simon Julianna
Published: December 2020

The color Doppler ultrasound twinkling artifact, which appears as a rapid color shift on some kidney stones, has recently been attributed to stabilized microbubbles. However, it is unknown what stone features allow these bubbles to form. Here, thirteen kidney stones were mechanically scanned in water using a research ultrasound system (Vantage, Verasonics, Kirkland, WA) at 2.5 MHz (C5-2, Philips, Bothell, WA), 5 MHz (L7-4, Philips, Bothell, WA), and 18.5 MHz (L22-14v, Verasonics, Kirkland, WA). Three-dimensional maps of Doppler power were generated using saved I/Q data. Then, six stones were imaged with either environmental scanning electron microscopy (ESEM) (Philips/FEI XL-20) or underwater micro-computed tomography (μCT) (GE v|tome|x L300, Wunstorf, Germany) at ambient and hypobaric pressures. Twinkling on all 13 stones was consistent over repeated trials and significantly lower at 18.5 MHz compared to 2.5and 5 MHz. ESEM showed water condensed on the smallest surface pores (∼1 μm diameter) as humidity increased. μCT showed gas trapped inside 2/3 stones that may contribute to twinkling. Future work includes investigating other pathological mineralizations to determine the role of chemical composition and growing conditions on bubble formation and twinkling. [Work supported in part by the National Science Foundation 1943937.]
Modeling of electromagnetically excited noise and vibration of induction motor
Authors: Hu Xiaorui , Zuo Shuguang
Published: December 2020

For electric vehicles, acoustic noise of traction motor excited by electromagnetic force is one of the main sources of noise, especially when automobiles are driven at low speed where noise from other sources are comparatively low. To analyze the characteristics of the noise and propose noise reduction suggestions, an accurate noise prediction model is needed. In this paper, a multi-physics model to predict the electromagnetic force excited acoustic noise of induction motor is presented. First, a three-dimensional (3-D) transient electromagnetic model of the motor was established using finite-element method (FEM). The uneven distributed time-varying magnetic force was calculated, and the current harmonics due to pulse width modulation (PWM) supply were considered. Then, a structural model was built, in which the anisotropy characteristic of silicon sheets stacked stator core, as well as the influence of windings, were considered through the assignment of orthotropic parameters to the stator core. Through mesh mapping, the FEM calculated magnetic force was transferred onto the structural model and the forced vibration was calculated using mode superposition method. Base on that, the acoustic noise was further obtained using boundary-element method (BEM). Finally, the noise and vibration of the studied induction motor were tested in a semi-anechoic room. As the simulated results show a good accordance to the measured data, the accuracy of the model was verified.
On acoustic prediction models for the intrinsic parameters of rigid-frame porous media using Bayesian optimization
Authors: Horoshenkov Kirill V. , Xiang Ning , Hurrell Alistair
Published: December 2020

Knowledge of several intrinsic material parameters is crucial to the modeling accuracy of sound propagation in porous media. This paper studies the performance of several popular acoustic prediction models used to invert key intrinsic parameters of rigid frame porous media such as characteristic lengths, permeabilities and median pore size. These prediction models along with acoustic surface impedance experimentally measured with a standard impedance tube setup are evaluated in an optimization process which is essentially a Bayesian estimator. The effect of the number of intrinsic parameters in the model, sample thickness and frequency range on the accuracy of the Bayesian estimator is studied. The quality of model predictions is characterized using quantitative measures such as mean, variance and the interdependence of the estimated parameters. This paper also discusses uncertainties of the intrinsic parameters and effect of these uncertainties on the accuracy of the acoustic parameter prediction.
Broadband acoustic lens design using the principle of reciprocity and gradient-based optimization
Authors: Amirkulova Feruza , Gerges Samer , Norris Andrew N.
Published: December 2020

In this work, we will present a gradient-based optimization method for the design of an acoustic lens. This design is based on an optimization process using the semi-analytical optimization approach and applying the principle of reciprocity. Here, we will illustrate the use of acoustic reciprocity to define the pressure at the focal point due to a source located in a far-field. The reciprocity enables us to relate the response by configuration of scatterers for an incident plane wave in terms of the far-field Green's function. The idea differs from earlier inverse designs that use topology optimization tools and generic algorithms. The gradient-based optimization algorithm maximizes the sound amplification at the focal point by evaluating pressure derivative with respect to the cylinder positions and then perturbatively optimizing the position of each cylinder in the lens while taking into account acoustic the multiple scattering between the cylinders. Computations are performed on MATLAB using “fmincon” function with a MultiStart optimization solver, and supplying the gradient of pressure at the focus. The reciprocal formulation of inverse design of acoustic lens leads to the closed-form solution that takes lesser time to compute the absolute pressure and it gradients at the focal point. The numerical results for the optimization of the broadband acoustic lens will be illustrated for configurations of uniform rigid cylinders.
Demonstration of subjective sound preferences and jury studies in product noise control using countertop blenders
Authors: Barnard Andrew R. , Bouman Troy , Prabhu Suraj
Published: December 2020

Developing consumer products requires consideration of product noise. Product noise control is usually not as simple as measuring and reducing the sound pressure level as much as possible. For example, consumers will not purchase vacuum cleaners if they are too quiet because of a perception that they do not function as well as louder models. This demonstration uses three countertop blenders to teach students about subjective acoustics and jury studies. The demonstration will start with a blind acoustic comparison of three blenders and the audience will be asked for opinions on the blenders, based on sound alone. Those opinions will be compared to overall measured sound pressure levels, product costs, and product performance criterion. This demonstration is ideal for an introductory noise control course, or for community outreach as it is easily relatable for any level of audience, from K–12 to adults.
An acoustic resonator rocket: Reviving Dvorak's 1878 acoustic repulsion apparatus
Authors: Russell Daniel A.
Published: December 2020

When a Helmholtz resonator is driven with sufficiently high amplitude, the pressure difference between the inside and outside of the resonator and the non-uniform oscillating flow of air into and out of the resonator opening results in a reaction force on the resonator akin to rocket thrust. The earliest demonstration of “acoustic repulsion” using small Helmholtz resonators was reported by M. Dvorak [Philos. Mag. Ser. 5 6(36), 225 (1878)]. Lord Rayleigh explained that the average pressure inside the resonator is higher than the external atmospheric pressure, with the result that the “resonator tends to move as if impelled by a force” [Philos. Mag. Ser. 5 6(37), 270 (1878)]. This demonstration will show an updated version of Dvorak's 1878 apparatus using Christmas ornament balls as suggested by Uno Ingard, [Notes on Acoustics (Infinity Science Press, 2008), p. 336]. In addition to showing the resonator rocket in action and discussing its history and various theorical explanations, this demonstration will show how the amount of “thrust” may be measured with a mass balance and will attempt to visualize the flow in the neck of the oscillator.
Two methods for acoustic modeling of the saxophone mouthpiece
Authors: Wang Song , Scavone Gary , Maestre Esteban
Published: December 2020

The mouthpiece is one of the key components in determining the sound and the playability of the saxophone. Assuming plane-wave propagation inside the mouthpiece, two different models are proposed for acoustic modeling of the saxophone mouthpiece. First, a Transfer Matrix (TM) model is derived from a finite element model and is then validated by comparing the calculated input impedance of a mouthpiece-cone structure with measurements. Then, by adapting a methodology traditionally used in modeling the human vocal tract, a Geometric Model (GM) is used to approximate the mouthpiece as a series of acoustic tubes of varying cross-sectional areas, and its accuracy is examined by comparing it with the TM mouthpiece model. We couple both models to a measured input impedance of an alto saxophone and provide a comparison of both methods and their impact on different fingering configurations. Finally, we discuss applications in sound synthesis and in mouthpiece design.
The soprano saxophone adapted to different tone generators in comparison to prototype instruments
Authors: Braasch Jonas
Published: December 2020

The purpose of this project was to investigate the extent to which a prototype wind-instrument resonator could be equipped with various tone generators to meet basic expectations of Western music practice in terms of range, tonal balance, and intonation. Sound generators from a Renaissance cornett, a bassoon, a Chinese bawu, and an Armenian duduk were adapted to a soprano saxophone body to test this. Further, the saxophone was performed as a rim flute by blowing against the neck, and an extended didjeridu adapter was crafted as well. The adaptations were tested against the original instruments by comparing single tone recordings throughout the range of the instruments. The test criteria were the breadth of tonal range, achievable intonation accuracy, dynamic range, and the constancy of the frequency spectrum. Some of the variations, like the bawu-reed adaptation, were easy to play; others, like the cornett, required years of practice. It was possible to play each adapted instrument in tune throughout the range of the prototypical instrument from which the tone-generator was taken. The tonal spectra were generally between those of the original instruments, which provided the tone generator, and the spectrum of the soprano saxophone, which lent the body.
Nonlinear resonance of sphere-plane contacts inside a cylindrical container
Authors: Lin Kevin Y. , Prather Wayne , Mobley Joel
Published: December 2020

Cylindrical containers, such as liquid tanks, pressure vessels or nuclear dry storage casks, are ubiquitous in storage applications. In our previous work, we developed metrics to estimate the structural integrity of the mock-up fuel assemblies inside a simplified lab-scale nuclear dry storage cask using sensors located strictly on the outside surface. However, the linear acoustic techniques applied have limited ability to differentiate between an absent mock-up fuel assembly and one that has fully decayed. In this work, we further examine this problem by studying contact nonlinearity in a more simplified system using Nonlinear Acoustic Resonance Spectroscopy. This system consists of a single layer of spheres of different composition and size evenly distributed at the bottom of an open aluminum cylindrical container. No extra normal force other than gravity was exerted on the spheres. The excitation source and the sensor are located at the outside surface. The system was driven close to the (1, 2) global bending mode at various excitation amplitudes, and the resonance frequencies as a function of the amplitude were recorded. The results show that this type of contact nonlinearity is mostly affected by the total mass of the spheres inside, while the diameter and composition of the spheres play minor roles. A phenomenological model was developed based on the experimental results and investigated using Finite Element simulations.
The performance of time reversal in elastic chaotic cavities as a function of volume and geometric shape of the cavity
Authors: Anderson Brian E. , Barker Paige E.
Published: December 2020

Time reversal is used as an energy-focusing technique in nondestructive evaluation applications. Here, it is often of interest to evaluate small samples or samples that do not lend themselves to the bonding of transducers to their surfaces. A reverberant cavity, called a chaotic cavity, attached to the sample of interest provides space for the attachment of transducers as well as an added reverberant environment. Reverberation is critical to the quality of time reversal focusing. The goal of this research is to explore the dependence of the quality of the time reversal focusing on the size and geometric shape of the chaotic cavity used. An optimal chaotic cavity will produce the largest focusing amplitude, best spatial resolution, and linear focusing of the time reversed signal. Ultrasonic, elastic-wave experiments are performed on rectangular, cylindrical, and 3-D Sinai billiard prism samples. Experiments are repeated each time these samples are successively cut down to smaller volumes. As the size of the cavity decreases, the peak amplitude may increase or decrease depending on the normalization scheme employed. The higher the degree of ergodicity of the cavity, the higher quality focusing achieved.
Characteristic spectral analysis of turbulent-flow-induced noise in rivers
Authors: Brady James R. , Gee Kent L. , Transtrum Mark K.
Published: December 2020

This talk describes the characteristic spectra resulting from turbulent water flow in multiple sections of the Provo and Colorado Rivers in Utah. For reference these rivers are characterized as medium-sized bedrock rivers, with Strahler orders of 5 and 7, respectively. Larson Davis 831C sound level meters were used to obtain two-second, one-third octave time histories. The spectra appear to be the superposition of two characteristic spectral curves possibly resulting from two different interactions within the turbulent section of the river. This two-source model for characterizing turbulent flow induced acoustics is similar to that observed in both the characteristic spectra for jet aircraft and for turbulent plasma flow. The higher frequency curve peaks between 700 and 1100 Hz and is almost certainly due to the Minnaert Frequency associated with resonating bubbles in the stream. This process and spectral curve appear similar to the fine spectral curve associated with Jet aircraft noise. The second curve is lower in frequency and peaks around 150 Hz and is most likely a result of interaction between the turbulent water and the ground.
An effect of eye position in cocktail party listening
Authors: Best Virginia , Jennings Todd R. , Kidd Gerald
Published: December 2020

Previous studies have noted an interaction between eye position and auditory spatial attention, including a tendency to look towards the location of an attended sound (even in the absence of useful visual information). There can also be objective improvements in the detection and discrimination of sounds when the eyes are directed to their location. In the current study, we were interested in whether there is a measurable effect of eye position in “cocktail party” listening situations. We presented five sequences of digits from five loudspeakers positioned at 0 deg,  ± 15 deg, and  ± 30 deg azimuth, and asked participants to repeat back the digits presented from one target loudspeaker. In different blocks of trials, the participant was instructed to visually fixate on the target loudspeaker or on a non-target loudspeaker. Head position was stabilized with a neck-rest, and eye position was tracked continuously to monitor compliance. Performance was best when eye fixation was on-target, and suffered when eye fixation was off-target, particularly for targets located in the center. This result demonstrates an influence of eye position in multitalker mixtures, even in the absence of visual information (lip-reading, etc.), and suggests that optimal performance depends on the spatial alignment of auditory and visual attention.
Acoustical case studies of large high power hydroelectric generators: Correlation between acoustic and vibration measurements
Authors: Lafleur Francois , Kirouac Mathieu
Published: December 2020

In power plants, acoustical signals are generally easier to measure than vibration signals at specific location because the security procedures are restricting the installation of accelerometers during the operation of the hydroelectric group. Specific acoustical measurements have been developed at the Hydro-Québec research center to set some maintenance actions or to gain more information about the operating conditions of the hydroelectric groups. These include acoustical airborne and structure-borne pressure measurements with conventional microphones at different locations around and inside the generator (including a microphone on the rotor) to correlate with vibration signals. Also, several vibration measurements were performed to allow ODS “Operating Deflection shape” of the generator displacement and correlation studies with the acoustic signals. Furthermore, some acoustical intensity measurements for mapping the generator floor permit the illustration of the emission pattern of the generator. All these acoustical measurements are interpreted in terms of operating conditions and specific frequencies. These acoustical and vibration measurements that were performed on several hydroelectric groups will be presented. The main goal of these measurements is to make multiphysics links between the acoustic, vibration and electromagnetic signals to perform non invasive maintenance and increase knowledge of the hydroelectric groups.
Implications of modern classroom architectural design and pedagogy on meeting ANSI S12.60 national classroom acoustics standard requirements
Authors: Woolworth David s.
Published: December 2020

21st century architectural design includes familiar acoustical challenges such as daylighting, but also includes flexible spaces that recall the modern multi-environment office design and their architectural minimalism. This investigation examines the core elements of the modern classroom design and the resulting acoustical design challenges to meet the national classroom standard. The data, decision processes, and solutions presented are taken from a school currently under construction.
Final Master's project advised by Jiri Tichy on architectural acoustics
Authors: Loubeau Alexandra
Published: December 2020

Jiri Tichy's interest and expertise in architectural acoustics research led to the formulation of a Master's student project on the irregularity of low-frequency response in small rooms. The numerical study conducted under the guidance of Dr. Tichy by the present author addressed how to decrease the low-frequency sound field variability using a loudspeaker source with constant sound power radiation. A summary of the research results will be presented in terms of standard deviation, as a function of source position, receiver position, and room absorption. In addition, the presentation will include how this research experience instilled in the author a desire to continue pursuing acoustics research.
Speech intelligibility in the primary classroom: What if the teacher has voice problems
Authors: Bottalico Pasquale , Murgia Silvia
Published: December 2020

School children need clear auditory signals and low background noise to learn. When classroom acoustics are poor, teachers often compensate by raising their voices, usually with limited effect against background noise, and, long-term, this makes vocal overuse the primary cause (60%) of the high prevalence of voice problems in teachers. Speech intelligibility tests were performed in primary schools with normal hearing students using words produced by an actor with normal voice quality and simulating a dysphonic voice. The speech was played by a Head and Torso Simulator. Artificial classroom noise and classrooms with different reverberation times were used to obtain a range of Speech Transmission Index from 0.2 to 0.7 (from bad to good). Results showed a statistically significant decrease in intelligibility when the speaker was dysphonic with a maximum of 15% intelligibility loss. This study extends an important pairing of problems related to student learning: classroom acoustics and teachers with voice disorders. It provides important insights into the enormous variability in speech intelligibility in classrooms by characterizing students' intelligibility when students receive degraded auditory input. The degraded auditory input results from the intersection of classroom acoustics and poor teacher voice quality.
Source levels and propagation modelling of whistles from a free-ranging rough-toothed dolphin
Authors: Bittencourt Lis , Barbosa Mariana , Santos-Neto Elitieri , Bisi Tatiana , Lailson-Brito José , Azevedo Alexandre
Published: December 2020

A lone adult individual of rough-toothed-dolphin had its acoustic behavior recorded with a calibrated system (Fostex FR22: 192 kHz sampling rate; C54 hydrophone: -165.0 dBV, 0.009 Hz–100 kHz). Moments when the animal approached and faced the hydrophone were noted. Whistles were counted in Raven 1.6 (Hann window, 512, 50% overlap). Duration (ms), minimum, maximum and peak frequencies (kHz), number of steps and step frequency (kHz) were extracted of whistles emitted when the animal was in a 1-m radius of the hydrophone. Source levels (SL) were estimated through power spectral density calculation in Matlab. SL at frequency parameters and at each whistle step were extracted and used in bellhop propagation models of a coastal scenario. 63 whistles were emitted within 1m. Frequencies ranged from 1.2 to 9.7 kHz and duration from 115.3 to 825.6 ms. Frequency and SL increased with step number, with 4.5 steps per whistle. Minimum frequencies (1.9 ± 0.6 kHz) had smaller SL (125.2 ± 4.2 dB re 1 μPa) and decreased to 100 dB before 500 m. Peak frequencies (6.7 ± 1.0 kHz) had mean SL of 149.5 ± 8.5 dB re 1 μPa and reached 2500 m with 100 dB. Higher frequencies reached longer distances and depths.
Can we map the entire global ocean seafloor by 2030?
Authors: Mayer Larry A.
Published: December 2020

Recognizing the poor state of knowledge of ocean depths and the critical role such knowledge plays in understanding and maintaining our planet, the Nippon Foundation challenged the mapping community to produce a complete map of the world ocean seafloor by 2030. The resulting project, Seabed 2030, has already increased publicly-available data holdings of modern multibeam sonar data from 9% at the start of the effort in 2018 to 19% in the latest release of the GEBCO bathymetric compilation. Much of this initial increase has come through discovery of existing data. The challenge now is to complete new mapping (at resolution much higher than that achievable by satellite-altimetry derived bathymetry), an effort estimated to require approximately 200 ship-years (at a cost of $3-5B) using current technologies. Meeting this challenge will require innovative new technologies that can increase efficiency, cost-effectiveness and, capabilities. Autonomous vehicles can deliver standard mapping systems without the significant cost of crews and wind-powered autonomous systems, without the cost of crews or fuel. The real challenge however, is an acoustic one. Are new approaches to deep-sea mapping feasible that will represent a quantum leap in technology and make the aspirational goal of Seabed 2030 a reality?
Limitations on nonlinear fractional calculus models used in biomedical acoustics
Authors: Simon Blake E. , Cormack John M. , Hamilton Mark F.
Published: December 2020

Fractional calculus models used for biomedical ultrasound are associated with attenuation proportional to ωy, where y is typically in the range 1 < y < 2. To determine whether the attenuation and accompanying dispersion are sufficient to stabilize shock formation, the models are formulated as a Burgers equation with the traditional loss term replaced by a fractional derivative of order y. For y < 1 the resulting equation predicts unphysical solutions beyond the shock-formation distance. The second example pertains to nonlinear Lucassen interface waves, a model equation for which has been proposed to describe mechanical perturbations that accompany the transmission of nerve impulses. Linear Lucassen waves are defined by a second-order space derivative and a fractional time derivative of order 3/2, which falls between order 2 in the wave equation and order 1 in the diffusion equation. The resulting attenuation is proportional to ω3/4, and the corresponding nonlinear “fractional diffusive waves,” while strongly attenuated on the scale of a wavelength, may be lacking essential physics beyond the predicted shock-formation distance. Calculations are presented that determine wave amplitudes and propagation distances for which these two fractional calculus models may be of questionable physical significance due to nonlinearity. [B.E.S. is supported by the ARL:UT McKinney Fellowship in Acoustics.]
Acoustical properties of T-waves generated by 2011 Tohoku earthquake
Authors: Ko Myungkwon , Ryu Hyun-jung , Shin Sung Won , Park Sun-Cheon , Choi Jee Woong
Published: December 2020

T-wave is an underwater acoustic wave generated by submarine earthquake and propagated to a long distance through the SOFAR channel. T-wave can be received by a hydrophone located in the minimum sound velocity layer of the SOFAR channel, and thus can be applied to the detection of submarine earthquake. In this study, the T-waves received by hydrophones installed at International Monitoring System hydroacoustic station, HA11 after being generated by 2011 Tohoku earthquake was analyzed to investigate the possibility of early tsunami warning. The station HA11 is located near Wake Island, about 3100 km from the epicenter of the Tohoku earthquake. Transmission losses as a function of frequency were predicted using a range-dependent acoustic model, RAM and used to predict the source spectral density of the T-wave. The results presented in this talk may be applied to the tsunami early warning system. [This research was supported by the Korea Meteorological Institute (Grant No. KMI2018-02510).]
Novel uses of ultrasound in various lung diseases
Authors: Egan Thomas M. , Mohanty Kaustav , Ali Mir , Blackwell John , Ulrich Micah , Muller Marie
Published: December 2020

Conventional ultrasound (CUS) has been used in the chest to visualize pleural and pericardial fluid collections, diaphragm motion, and blood flow through the heart for anatomic definition and determining pressure gradients across valves. CUS is NOT suitable for imaging lung parenchyma, because of ultrasound multiple scattering (USMS) from millions of air-filled alveoli providing air-tissue interfaces. We used USMS to characterize lung tissue. We measured scattered mean free path (SMFP), the average distance between two scattering events, related to the amount of air present in lung parenchyma, and backscatter frequency shift (BFS), a measure of ultrasound attenuation. Using a rat bleomycin pulmonary fibrosis model, we showed that SMFP was longer in 18 rat lungs with pulmonary fibrosis, compared to 6 normals, and correlated with severity of lung fibrosis assessed by ex vivo CT scan and inflation-fixed histology. SMFP was significantly longer in 6 rat lungs made edematous by ischemia-reperfusion injury with significantly lower BFS. These data support using USMS to characterize severity of pulmonary fibrosis and pulmonary edema due to heart failure, and pneumonia and congestion in humans. In seven large animal lungs, determining the absence of USMS allows localization of pulmonary nodules for minimally invasive surgery. USMS provides many clinical opportunities.
The impact of B-lines' frequency characterization on lung ultrasound imaging, in vitro- and in vivo study
Authors: Mento Federico , Soldati Gino , Prediletto Renato , Demi Marcello , Demi Libertario
Published: December 2020

Lung ultrasound (LUS) is an established technique that allows clinicians to evaluate the state of the lung surface. However, LUS is based on the visual evaluation of imaging artifacts (e.g., A- and B-lines) and is hence affected by qualitative and subjective interpretations. Moreover, the impact of imaging settings on the visualization of artifacts is still greatly unknown. To shed light on these fundamental aspects of LUS, the results from two studies are presented. The first analyses through controlled in vitro- experiments the dependence of B-lines on three key imaging parameters, viz., center frequency, focal point, and active-aperture size. The second investigates thanks to a clinical study involving 26 patients the potentiality of B-line frequency characterization to differentiate pulmonary fibrosis from other diseases. A multi frequency imaging approach was used. Center frequencies ranging from 3 to 6 MHz and from 3 to 12 MHz were investigated for the invivo and in vitro- study, respectively. Raw RF data were acquired with a ULA-OP platform and a LA533 linear array probe. Results show that the imaging frequency significantly influenced the intensity of B-lines and that their frequency characterization can be exploited to discriminate fibrotic patients with a sensitivity and specificity equal to 92%.
Performance analysis of an enclosed, coaxial carbon nanotube (CNT) speaker in presence of flow using COMSOL Multiphysics
Authors: Prabhu Suraj , Barnard Andrew R.
Published: December 2020

Carbon Nanotube (CNT) speakers are solid state speakers that operate on the thermovicsous acoustic principle. These speakers generate sound proportional to the oscillations in the surface temperature of the CNT film on application of an alternating current. CNT films are flexible, stretchable, transparent and extremely lightweight. These properties make it possible to manufacture the CNT speakers in a variety of shapes such as cylindrical, spherical, etc. An enclosed, coaxial CNT speaker was designed for noise cancellation in exhausts, ducts, etc. The enclosed design was simulated using COMSOL Multiphysics without the presence of flow in the medium of operation. In this study, simulations are carried out by introducing flow in the medium, particularly with different Mach numbers. The turbulent flow model results of a simple pipe are compared with the results obtained from Fluent to verify the COMSOL Multiphysics model. Then an enclosed, coaxial CNT speaker model is simulated in COMSOL Multiphysics by mapping the CFD mesh parameters on an acoustic mesh. The results obtained are compared with the simulation results from no-flow condition. This study helped to understand the effect of different Mach number turbulent flows on the sound pressure level generated by the enclosed, coaxial CNT speaker.
Acoustical demonstration of slurring characteristics using a French horn
Authors: Bixler Tiffany A. , Korman Murray S.
Published: December 2020

In this experiment, we will be attempting to re-create Shona Marie Logie's slurring experiments where a Conn 8D (modern wide bore horn), a Boosey and Hawkes horn, and a trumpet were the selected brass instruments. [S. M. Logie, “An acoustical study of the playing characteristics of brass wind instruments,” Ph.D. thesis (University of Edinburgh, 2012)]. However, instead of the instruments mentioned above, experiments will be performed using an “F” horn. Our goal is to inform students about musical acoustics and slurring by doing some fundamental experiments. When conducting the experiments (in two parts), we perform (1) forced oscillation slurring experiments where the mouthpiece is driven by a loudspeaker and utilize two different microphones (located near the mouthpiece and near the bell) and (2) conduct experiments where the performer is slurring using an excerpt of a musical arrangement. Experiments will be conducted in a soundproof room and an anechoic chamber. We will be using an excerpt from Turandot, by Giacomo Puccini and arranged (for French horn) by Robert van Beringen, called Nessun Dorma (meaning “Let no one sleep”).
Circular synthetic aperture ultrasonic acoustic imaging using a 2.25 MHz underwater sonar
Authors: Twitty Ava B. , Korman Murray S.
Published: December 2020

Experiments were performed in the USNA physical acoustics lab to demonstrate underwater sound imaging using circular synthetic aperture acoustic C-SAA imaging in two dimensions. The apparatus includes a single 2.25 MHz submersion transducer acting as both transmitter and receiver (2.54 cm diam with a manufacture's specified 4 cycle pulse shape) located 15 cm from the target's center. A structure of thin perforated disks (7.6 cm diameter) comprise a step-motor controlled rotational platform that supports several slender stainless steel cylindrical rod vertical targets (2 mm diameter, 10 cm long). The apparatus and supporting electronics serves in part as a teaching tool for imaging targets in a laboratory environment. This setup might be called inverse C-SAA considering a medical imaging tomography arrangement where the transmitter-receiver is fixed while the targets rotate at small angular intervals. Here, the platform “stops” for an echo versus time measurement and then rotates (or “hops”) to the next location for the following measurement. The transmitted pulse is generated by a rectangular pulse (duration T = 0.5/2.25 MHz) or utilizing a short tone burst. Correlation pulse compression can be used if a chirp is transmitted. A back-projection algorithm performed on Mathematica® was used to generate a 2-D reflectance image—for several targets.
Spectral analysis of turbulent boundary layer pressure fluctuations collected by a MEMS microphone array
Authors: Saff Ethan , White Robert D.
Published: December 2020

A MEMS-based microphone array was previously constructed to collect and measure pressure fluctuations due to turbulence under flat plate turbulent boundary layers with high spatial resolution (≈1.3 mm). Data were collected from this array at Mach numbers up to 0.6 and Reynold's numbers up to 107 per meter in three flow facilities, at NASA Ames, the Univ. of Toronto, and Spirit Aerosystems. The measured pressure fluctuations are being processed to identify the turbulence characteristics of the data. Comparisons of the single point power spectral density to previously existing models, such as those of Chase and Goody, as well as wave speed estimates derived from the phase slope, suggest that turbulent characteristics are significantly present in the measured data. In a variety of different cases, the data will be compared to the Corcos model for cross spectral density in streamwise, spanwise, and intermediate directions to further confirm the data's validity and to quantitatively investigate the validity of the separable model used in Corcos's expression.