bluuebunny/crossref_metadata_2025 huggingface dataset:
Determining day‐to‐day human variation in indirect calorimetry using Bayesian decision theory
Authors: Tenan Matthew S. , Bohannon Addison W. , Macfarlane Duncan J. , Crouter Scott E.
Published: October 2018

New Findings

What is the central question of this study?

We sought to understand the day‐to‐day variability of human indirect calorimetry during rest and exercise. Previous work has been unable to separate human day‐to‐day variability from measurement error and within‐trial human variability. We developed models accounting for different levels of human‐ and machine‐level variance and compared the probability density functions using total variation distance.

What is the main finding and its importance?

After accounting for multiple levels of variance, the average human day‐to‐day variability of minute ventilation, CO2 output and O2 uptake is 4.0, 1.8 and 2.0%, respectively. This is a new method to understand human variability and directly enhances our understanding of human variance during indirect calorimetry.

One of the challenges of precision medicine is understanding when serial measurements taken across days are quantifiably different from each other. Previous work examining gas exchange measured by indirect calorimetry has been unable to separate differential measurement error, within‐trial human variance and day‐to‐day human variance effectively in order to ascertain how variable humans are across testing sessions. We used previously published reliability data to construct models of indirect calorimetry variance and compare these models with methods arising from Bayesian decision theory. These models are conditional on the data upon which they are derived and assume that errors conform to a truncated normal distribution. A serial analysis of modelled probability density functions demonstrated that the average human day‐to‐day variance in minute ventilation (), carbon dioxide output () and oxygen uptake () was 4.0, 1.8 and 2.0%, respectively. However, the average day‐to‐day variability masked a wide range of non‐linear variance across flow rates, particularly for . This is the first report isolating day‐to‐day human variability in indirect calorimetry gas exchange from other sources of variability. This method can be extended to other physiological tools, and an extension of this work facilitates a statistical tool to examine within‐trial differences, available in a graphical user interface.
Chinese water mites of the genus Torrenticola Piersig, 1896 (Acari, Hydrachnidia, Torrenticolidae), with descriptions of two new species and a new record from Foding Mountain
Authors: Gu Xinyao , Jin Daochao , Yi Tianci , Guo Jianjun
Published: October 2018

Three water mite species of the genus Torrenticola Piersig, 1896 are reported from Foding Mountain National Nature Reserve, Guizhou Province, China. Torrenticola fodingensis Gu & Guo, n. sp. and T. tenuichelicera Gu & Guo, n. sp. are described and illustrated as new to science, and T. nipponica (Enami, 1940) is recorded in China for the first time, with the first description and illustration of its deutonymph. In addition, a key to the species ofTorrenticola in China is presented in this paper. The type specimens of the new species are deposited in Institute of Entomology, Guizhou University, Guiyang, P. R. China (GUGC).
A hybrid approach for using programming exercises in introductory physics
Authors: Orban C. M. , Teeling-Smith R. M. , Smith J. R. H. , Porter C. D.
Published: October 2018

Incorporating computer programming exercises into introductory physics is a delicate task that involves a number of choices that may have an effect on student learning. We present a “hybrid” approach that speaks to a number of common concerns regarding cognitive load which arise when using programming exercises in introductory physics classes where many students are absolute beginner programmers. This “hybrid” approach provides the student with a highly interactive web-based visualization, not unlike a PhET or Physlet interactive, but importantly the student is shown only the subset of the code where the initial conditions are set and the system variables are evolved. We highlight results from a coding activity that resembles the classic game Asteroids. The goals of this activity are to show how a simple 1D code can be modified into a 2D code, and to reinforce ideas about the relationship between force, velocity, and acceleration vectors. Survey results from four semesters of introductory physics classes at the Ohio State University's Marion campus, in which a high percentage of the students are weak or absolute beginner programmers, provide evidence that most students can complete coding tasks without severe difficulty. Other survey results are promising for future work where conceptual learning will be assessed in a direct way using metrics like the Animated Force Concept Inventory [Dancy and Beichner, Phys. Rev. Spec. Top. Phys. Educ. 2, 010104 (2006)]. The exercise highlighted here and others from our group are available for general use at http://compadre.org/PICUP.
Multitaper harmonic analysis of infant vocalizations
Authors: Ramsay Gordon
Published: October 2018

Infant vocalizations exhibit many special complexities relative to adult speech that make acoustic analysis difficult, even though the basic physics of sound production in the vocal tract is identical. Fundamental frequency is raised, resulting in wider-spaced harmonics that make it hard to accurately estimate the spectral envelope or locate formant resonances, which are higher than in adult voices, due to anatomical scaling effects. Irregular vocal fold vibratory regimes are often observed, involving period doubling and other nonlinear phenomena not seen in adult speech, along with atypical patterns of turbulent noise production. Unsurprisingly, traditional analysis techniques that depend on estimating the spectral envelope from the speech signal do not work well when applied to infant vocalizations. An alternative approach is proposed, using multitaper analysis to calculate the time-varying amplitude and phase of every harmonic component of the voice, along with the residual noise component, recovering the vocal tract transfer function from the results. The new technique is compared against linear prediction and cepstral analysis using home audio recordings of 20 infants collected from 0 to 24 months using LENA technology. Developmental progressions in the acoustic structure of the infant voice are identified that cannot be found using traditional methods.
Passive source depth discrimination in deep-water
Authors: Emmetiere Rémi , Bonnel Julien , Gehant Pernot Marie , Chonavel Thierry
Published: October 2018

In this work, we address the problem of passive source depth discrimination using a horizontal line array (HLA). The scope is restricted to low-frequency sources (f<500 Hz), broadband signals (a few Hertz bandwidth), deep-water environment (D>1000 m), and distant sources (at least several kilometers). The proposed method is based on the underlying physics driving the propagation. It notably uses the concept of mode trapping and waveguide invariant. In deep water, the waveguide invariant largely depends on source depth, and is thus an interesting input for source depth discrimination. An algorithm is proposed to compute energy ratio in modal groups. The input data for the algorithm are a range-frequency intensity, as measured on a HLA. The modal groups are thus defined based on their respective waveguide invariant values, which is a main difference with existing depth discrimination methods adapted to shallow water context. This idea is explored, and extended to propose a source depth discrimination which is performed as a binary classification problem. As long as the sound speed profile features a surface thermocline, the algorithm does not require detailed knowledge about the environment and it allows one to classify sources under two hypotheses, above or under a threshold depth.
Optimization of deployment depth for active towed array sonar (ATAS) using simulated annealing
Authors: An Sangkyum , Lee Keunhwa , Seong Woojae
Published: October 2018

The active towed array sonar (ATAS) is an active operating sonar towed behind the surface ship and deployed at various depths. The performance of ATAS may vary with the deployment depth. This study proposes a method which calculates the optimal deployment depth using simulated annealing (SA) in order to reduce the total computational time spent in the direct search of the deployment depth. We define a sonar performance function (SPF) with the probability of detection, which represents as a degree of how well the ATAS might perform at particular deployment depth. Then, the optimal depth is defined as the depth where the SPF is maximized. The SPF depends on the acoustic environment, target position and source-receiver depth. The optimization results are compared with the direct calculation of SPF at all deployment depth of source and receiver. Also, our study provides the optimal depths in the area of East Sea of Korea.
Biosonar-mediated prey tracking in air and in water—The fast and the persistent
Authors: Wisniewska Danuta M. , Johnson Mark , Vance Heather , Stidsholt Laura , Madsen Peter T.
Published: October 2018

Microchiropteran bats and toothed whales are the only taxa to echolocate for prey. The two biosonar systems have evolved independently, in media with very different physical properties that determine the production, propagation, and reflection of sound, as well as the means and speeds with which the echolocating predators and their prey can move and maneuver. Yet, they have converged on remarkably similar acoustic behavior; the animals adjust the timing and level of their sound emissions as they near their targets, eventually entering the buzz phase with high rates of low-amplitude signals. But while the buzz of a bat lasts a fraction of a second, prey pursuits by toothed whales are one to two orders of magnitude longer. Here, we explore these differences and their consequences for biosonar performance and prey capture success. We use echograms recorded with acoustic dataloggers on porpoises to show that, like some bat species, porpoises hunt in different environments targeting several types of prey and adjusting their biosonar outputs to manage different acoustic soundscapes. However, we further show that, unlike bats, porpoises are able to carefully track their prey with adjusted click intervals and dynamically accommodate prey movements to provide high spatial resolution without range ambiguities.
Burst wave lithotripsy: An in vivo demonstration of efficacy and acute safety using a porcine model
Authors: Wang Yak-Nam , Kreider Wayne , Hunter Christopher , Cunitz Bryan , Thiel Jeffrey , Starr Frank , Dai Jessica , Nazari Yasser , Lee Donghoon , Williams James C. , Bailey Michael R. , Maxwell Adam D.
Published: October 2018

Burst wave lithotripsy (BWL) is a new non-invasive method for stone comminution using bursts of sub-megahertz ultrasound. A porcine model of urolithiasis and techniques to implement BWL treatment have been developed to evaluate its effectiveness and acute safety. Five human calcium oxalate monohydrate stones (6–7 mm) were hydrated, weighed, and surgically implanted into the kidneys of three pigs. Transcutaneous stone treatments were performed with a BWL transducer coupled to the skin via an external water bath. Stone targeting and treatment monitoring were performed with a co-aligned ultrasound imaging probe. Treatment exposures were applied in three 10-minute intervals for each stone. If sustained cavitation in the parenchyma was observed by ultrasound imaging feedback, treatment was paused and the pressure amplitude was decreased for the remaining time. Peak negative focal pressures between 6.5 and 7 MPa were applied for all treatments. After treatment, stone fragments were removed from the kidneys. At least 50% of each stone was reduced to <2 mm fragments. 100% of four stones were reduced to <4 mm fragments. Magnetic resonance imaging showed minimal injury to the functional renal volume. This study demonstrated that BWL can be used to effectively fragment kidney stones with minimal injury. [Funding support: NIH P01-DK043881, NIH K01-DK104854.]
Assessing the concept of resonance through the lens of discipline-based educational research
Authors: Morrison Andrew C.
Published: October 2018

In the last few decades, many science and engineering fields have developed educational research programs specific to their fields. These discipline-based educational research programs are critical for improving the learning environments of the next generation of scientists and engineers. Acoustics is a highly interdisciplinary field, drawing from a wide variety of science and engineering fields. Although no major acoustics educational research program currently exists, acoustics educators should be aware of discipline-based educational research findings which most closely align to their particular branch of acoustics. Educational research can inform educators on how students develop content expertise as well as grow in their thinking about the practice of science and engineering. One of the ways that discipline-based educational research informs educators about the way students think about science content and practices is through the use of assessment instruments. Some assessment tools related to acoustics have been developed by the physics education community, although the selection remains somewhat limited. An attempt to develop an instrument for assessing the concept of resonance as well as the challenges for validating the instrument is presented.
Numerical modeling of ultrasound propagation in heterogeneous media using a mixed domain method
Authors: Jing Yun , Gu juanjuan
Published: October 2018

A mixed domain method (MDM) is presented in this paper for modeling one-way linear/nonlinear wave propagation in biological tissue with arbitrary heterogeneities, in which sound speed, density, attenuation coefficients, and nonlinear coefficients are all spatial varying functions. The MDM is based on solving a Westervelt-like equation. We validated the algorithm by studying a number of one-dimensional and two-dimensional problems. Overall, this study demonstrates that the MDM is a computationally efficient and accurate method when used to model wave propagation in biological tissue with relatively weak heterogeneities. We also proposed methods to improve the algorithm for moderately heterogeneous media.
Machine learning-based prediction of outdoor ambient sound levels: Ensemble averaging and feature reduction
Authors: Pedersen Katrina , Gee Kent L. , Transtrum Mark K. , Butler Brooks A. , James Michael M. , Salton Alexandria R.
Published: October 2018

Outdoor ambient sound levels can be predicted from machine learning-based models derived from geospatial and acoustic training data. To improve modeling robustness, median predicted sound levels have been calculated using tuned models from different supervised machine learning modeling classes. The ensemble-based model reduces errors at training sites for both overall levels and spectra, and produces more physically reasonable predictions elsewhere. Furthermore, the spread in the ensemble provides an estimate of the modeling accuracy. An initial analysis of feature importance metrics suggests that the number of geospatial inputs can be reduced from 120 to 15 without significant degradation of the model's predictive error, as measured by leave-one-out cross validation. However, the predictions from the reduced-feature modeling may be less physical in certain regions when all differentiating geospatial features are removed. These results suggest the need for more sophisticated data collection and validation methods.
Detection of bubble movements via wave phase conjugation
Authors: Modarreszadeh Amir , Timofeev Evgeny , Merlen Alain , Bou Matar Olivier , Pernod Philippe
Published: October 2018

Wave Phase Conjugation (WPC) means reversing the propagation of waves so that initial spatial distributions of amplitudes and phases are conserved. One of the methods to conjugate ultrasonic waves is to modulate the speed of sound in a solid conjugator by an alternating electromagnetic field. The detection of bubble motions in a fluid to be considered in this work is among potentially interesting and omnipresent WPC applications in industry. As the ultrasonic waves have short wavelengths, high-order in space and time numerical methods are required for modeling. In this work, a modified version of the Nodal Discontinuous Galerkin method, which is based on the non-collocated solution and flux bases, is implemented for wave propagation in solids and liquids (for both linear and non-linear flow regimes) in an axisymmetric geometry. Being assured of the accuracy and performance of the numerical technique by evaluating some representative test cases, the detection of bubble motion and growth in a flow field using WPC is simulated with the inclusion of all elements of the WPC process: the transducer, the conjugator, and the bubbly liquid itself. The developed methodology and results can be used to design and improve measurement devices based on the WPC phenomenon.
Your ears never sleep: Auditory processing of nonwords during sleep in children
Authors: Roman Adrienne , Benitez Carlos , Key Sasha , Tharpe Anne Marie
Published: October 2018

The auditory system in humans is the only sensory system that remains active for the continuous scanning and processing of information during sleep; however, little research has investigated this phenomenon. This study examined whether a brief exposure to auditory stimuli during sleep could result in memory traces indicated by event-related potentials (ERPs) in children. Twelve preschool children with normal hearing (2–5 years) were presented with three randomly selected nonwords (250 trials; 45–50 dB SPL) for 10 min during a regular nap (sleep state verified by EEG). After the nap, children’s memory for the stimuli was evaluated using a passive listening version of the “old/new” ERP paradigm that included three nonwords from the nap exposure (repeated condition, 45 trials), 3 new nonwords (sham repeated condition, 45 trials), and 45 other distinct nonwords (novel condition). Memory for the “nap exposure” words was reflected by increased positive amplitudes at midline parietal locations between 350 and 600 ms compared to the sham and novel conditions. This evidence of the memory trace for the auditory stimuli experienced during sleep can have implications for children with hearing loss who routinely remove their assistive devices during sleep. Preliminary results from children with cochlear implants will be discussed.
Effects of L2 proficiency on the production of voiceless stops
Authors: Jeon Ji-Hyun , Lee Seok-Chae
Published: October 2018

This study investigates how native speakers and L2 learners of English (L2 learners being native speakers of Korean) produce voiceless stops in English in the following phonological contexts: word-initial vs. -medial, stressed vs. unstressed, and when preceded by /s/. The study also examines the correlation between proficiency of L2 learners of English and the degree of aspiration (represented by VOT) in English voiceless stops. The speech of Korean L2 learners of English rated and categorized into 5 English proficiency levels in Genie Speech Corpus will be used. We will measure VOT of voiceless stops in the aforementioned conditions produced by 5 English speakers and each 5 Korean speakers per level. We expect that highly rated L2 speakers of English will produce longer VOT in stressed syllables than in unstressed syllables, as native speakers of English do. However, as the proficiency level gets lower, L2 speakers will produce it to a lesser degree than native speakers do, presenting a wide variety of VOT length.
CRSS-LDNN: Long-duration naturalistic noise corpus containing multi-layer noise recordings for robust speech processing
Authors: Hansen John H. L. , Dubey Harishchandra , Sangwan Abhijeet
Published: October 2018

Multi-layer noise refers to scenarios where multiple distinct noise sources are simultaneously active in an audio stream. We collected a corpus named the CRSS long-duration naturalistic noise (CRSS-LDNN) corpus. It contains noise captured from complex daily-life activities using wearable LENA units. The diversity in noise-sources include construction noise, noise like multi-speaker babble, large-crowd noise, vehicle/bus noise on the road, home environment noise, etc. Corpus contains recordings of complex mixtures of these noise types. The babble noise and bus-engine noise present along with occasional impulsive-noise over long-duration is an example of such scenario. The data were collected at 16 kHz sampling rate with 16-bit precision in .wav format. This data would be released to speech community (http://crss.utdallas.edu). During the summer semester, a CRSS student wore a LENA device that was switched ON when multiple noise-sources were present. This corpus was recorded in naturalistic scenarios with uncontrolled mixing of various noise-sources. It provides naturalistic multi-layer noise recordings for evaluation of robust speech algorithms such as speech recognition, speaker diarization and verification, sentiment analysis. It consists of approximately 19 hours noise recordings. The CRSS-LDNN noise is more challenging as compared to existing noise corpora such as NOISEX that contains only single noise.
The role of F2 and F3 in the perception of liquids for Hindi and Mandarin listeners
Authors: Howson Phil , Schertz Jessamyn L. , M. Irfana
Published: October 2018

Rhotics and laterals are often described as being separated by F3; however, recent work has described lower F2 as a distinguishing quality of rhotics. The current work examines the perception of liquids (rhotics and laterals) by Mandarin and Hindi listeners. Participants completed a forced-choice identification task on a set of 30 stimuli, manipulated from a natural Malayalam production /aɻa/ to vary systematically in F2 and F3. Listeners chose the consonant they heard from a set of approximants (/r/, /l/, /j/, and /w/ or /ʋ/). The results revealed that liquid identification was mostly confined to the mid F2 range, from 1228 Hz to 1728 Hz. Within that range, stimuli with the lowest F2 and F3 values were predominantly identified as rhotics, while those with the highest F2 and F3 values were identified as laterals. The F3 range of 1885 Hz–2135 Hz was ambiguous between rhotics and laterals. The data suggest that F2, as well as F3, plays a key role in rhotic identification, and suggest overlap in the F3 perceptual space for rhotics and laterals for Mandarin and Hindi listeners. The data suggest a complex relationship between F2 and F3 and liquid perception.
The stability of visual–aerotactile effects across multiple presentations of a single token
Authors: Kwan Sharon , Keough Megan , Taylor Ryan C. , Chan Terrina , Schellenberg Murray , Gick Bryan
Published: October 2018

Previous research has shown that the sensation of airflow causes bilabial stop closures to be perceived as aspirated even when paired with silent articulations rather than an acoustic signal [Bicevskis et al. 2016, JASA 140(5): 3531–3539]. However, some evidence suggests that perceivers integrate this cue differently if the silent articulations come from an animated face [Keough et al. 2017, Canadian Acoustics 45(3):176–177] rather than a human one. Participants shifted from a strong initial /ba/ bias to a strong /pa/ bias by the second half of the experiment, suggesting the participants learned to associate the video with the aspirated articulation through experience with the airflow. One explanation for the above findings is methodological: participants saw a single video clip while previous work exposed participants to multiple videos. The current study reports two experiments using a single clip with a human face (originally from Bicevskis et al. 2016). We found no evidence of a bias shift, indicating that the findings reported by Keough et al. are not attributable to the use of a single video. Instead, our findings suggest that aero-tactile cues shift consonant perception regardless of the number of recordings presented as long as the speaking face is human.
Concurrent aero-tactile stimulation does not bias perception of VOT for non-initial stops
Authors: Goldenberg Dolly , Tiede Mark , Whalen D. H.
Published: October 2018

Previous work has established that puffs of air applied to the skin and timed with listening tasks bias the perception of voicing in onset stops by naive listeners (Gick and Derrick, 2009; Goldenberg et al., 2015). While the primary cue for the voicing contrast in stops is VOT (Lisker and Abramson, 1964), in English aspiration typically functions as a cue foot initially. This study tests the effect of air puffs on perception of voicing for English stops in a non-foot-initial context (“apa/aba”) using VOT continua. Goldenberg et al. (2015) have shown that listeners are sensitive to aero-tactile effects only when these are congruent with the expected contrast (i.e., in VOT but not vowel quality distinctions). Since VOT is generally non-contrastive for English stops that are not foot-initial, air puffs were not expected to affect perception in the current case, and indeed, of 22 participants (11 females; mean age 34.2) tested, 20 showed no effect. Comparison of this null result to the significant bias observed in the earlier (foot-initial context) study extends the finding that, for aero-tactile stimulation to bias perception, the cues must be consistent with those expected in production of the perceived sounds.
Perception of sexual orientation through speech: Generational differences
Authors: Obeda Lily , Putman Melanie , Munson Benjamin
Published: October 2018

Previous research has shown that listeners can perceive talkers' sexual orientation at a greater than chance levels from the acoustic characteristics of their speech (Munson et al., J. Phonetics [2006]). Recently, Obeda and Munson (2018, J. Acoust. Soc. Am. 143, 1924) compared the perception of 44 gay, lesbian, and heterosexual people's sexual orientation through speech by the young adults reported in Munson et al. 2006 (whose data were collected in 2003) to a group of young adults tested in 2018. The new listeners were matched in age to the 2003 listeners. A number of differences between the two cohorts were found. In particular, the 2018 listeners were less willing to judge heterosexual women's speech as 'sounding heterosexual'. In this presentation, we compare both sets of data to the performance of a new set of listeners who are matched in birth year to the 2003 listeners, and who are currently 33–48 years old. Collection of those data is ongoing. Comparing this new group to the two other groups will allow us to examine whether the apparent generational change observed by Obeda and Munson has led listeners like those in 2003 to reevaluate their perception of sexual orientation through speech in 2018.
Visual gender biases in English stop voicing perception
Authors: Ting Connie , Soo Rachel , Schertz Jessamyn L.
Published: October 2018

Listeners leverage visual information, such as perceived speaker gender, during speech perception. While work has shown visual gender biases on fricative (Johnson & Strand, 1996) and vowel perception (Johnson et al., 1999), its effects on stop voicing perception are understudied. We present an identification task where visual gender primes (male/female portraits) were used to investigate perceived speaker gender effects on English stop voicing. Subjects (n = 22) identified ‘pa’/’ba’ syllables from an 11-step VOT continuum (0–50 ms) in 5 pitch levels (high: 250 Hz, 230 Hz, mid: 170 Hz, and low: 130 Hz, 110 Hz). High and low pitch tokens were always preceded by a female and male portrait, respectively. Mid pitch tokens were preceded by female or male images in separate blocks. Given that f0 is higher following voiceless obstruents (Lehiste & Peterson 1961; Mohr 1971), if listeners utilize visual gender cues, acoustically ambiguous tokens paired with a male portrait should elicit more voiceless "pa" responses than those paired with a female portrait. Preliminary results pattern in the expected direction; mid tokens are perceived as "pa" more when paired with a male (15–25 ms = 79% "pa" response) than a female face (73% "pa" response); however, this effect was not statistically significant.
Incorporating real-time acoustic ranging and glider-based Doppler measurements to aid vehicle navigation
Authors: Webster Sarah E. , Van Uffelen Lora J. , Shcherbina Andrey , Aravkin Aleksandr , Lee Craig M. , Worcester Peter F. , Dzieciuch Matthew
Published: October 2018

In the summer of 2017, two Seagliders equipped with low frequency acoustic recorders and 1 MHz acoustic Doppler current profilers (ADCPs) were deployed in the Canada Basin as part of a large-scale acoustic tomography experiment. Acoustic tomography sources were moored at approximately 175 m depth within an acoustic duct enabling acoustic transmission to be received at long ranges. The sources transmitted at a center frequency of approximately 250 Hz every four hours, and ranges between the sources and Seaglider were estimated in real time using a WHOI MicroModem. These ranges can be incorporated into an extended Kalman filter for navigation. In addition, glider-mounted upward-looking ADCPs recorded ~26.5 m shear profiles every 15 seconds. These overlapping profiles can be used to estimate (in post-processing) both the local current profile on a per-dive basis and the glider's relative velocity through the water. In real time, the close-range ADCP velocity measurements can be used to estimate the glider's relative (Through The Water, TTW) velocity to improve the glider's subsea position estimate. We will describe our recent developments in using these Doppler measurements to aid glider navigation, comparing the results to previous developments in range-aided navigation.
A method for passive localization of three-dimensional position
Authors: Song Mingyu , Li JiangQiao , Hui Juan
Published: October 2018

The movement operation of the machine installed on the ship and the ship itself will disturb the surrounding medium, and the vibration’s transmission forms the sound field of a ship. Analyzing the sound field of the target source has profound significance. The target three-dimensional position can be known according to the source of the noise radiated sonar-gram, this can be used for positioning the moving target source and tracking its trajectory A method using focused beam-forming to measure the distribution image (under-water image) of ship’s noise source which depth is unknown is presented in this paper. This is for the past open literature mentioned using a one-dimensional horizontal array for two-dimensional plane of the target source localization defects. The arrays cloth on the seafloor, when basing on the principles of geometrical acoustic and the superposition of important early reflected sound energy on direct sound energy, the three-dimensional coordinates of the target would be calculated. For the mentioned principle, this paper carried out the related analyzes simulation and the acoustic image verifies the feasibility of the algorithm. The distance would bring in focused-peak broadening, positioning-error increasing, by dividing frequency band, the phenomenon could be restrained and the problem could be improved. The results show that the method can locate the target quickly and accurately, and it can be used in the fixed arrays offshore areas.
Compressive normal mode estimation in shallow water
Authors: Park Yongsung , Seong Woojae , Gerstoft Peter
Published: October 2018

Estimation of normal modes in an ocean waveguide from acoustic data on a vertical line array involves estimation of mode shapes and their wavenumbers. Since these horizontal mode wavenumbers are sparse, compressive sensing (CS) can solve the sparse signal reconstruction problem with high accuracy. Here, grid-free CS technique, atomic norm minimization (ANM) is used to estimate the horizontal mode wavenumbers and their mode shapes. These mode shapes and wavenumbers can be estimated using the grid-free CS without a priori knowledge of the environment. The grid-free CS successfully extracts mode shapes and wavenumbers even with a partial water column spanning array and even in the case when the mode shape functions are not orthogonal.
Studying underwater sound level caused by bridge traffic in Lake Washington
Authors: Abadi Shima , Flett Derek , Berge Ryan , DeHaan Jeremy , Guy Virdie , Qureshi Urooj , Cook Michael
Published: October 2018

Underwater noise pollution due to human activities has greatly increased in recent years. There are several studies on high-intensity impulsive noises such as pile driving and seismic exploration. However, less is known about the effects of long-term exposure to low-intensity noises such as those due to bridge traffic. To characterize such noises, we have designed an underwater recording package. This package is equipped with a hydrophone to measure noise, a Raspberry-Pi to control recordings, and a cellular modem to stream near real-time data to the cloud. Data is collected in Lake Washington at two locations: (1) close to the Evergreen Point floating bridge across Lake Washington that connects Seattle to its eastern suburbs and (2) far from the bridge in the middle of the lake for comparison. The Evergreen Point floating bridge, the longest floating bridge in the world, is made of 77 large water-tight concrete pontoons and capable of carrying over 70,000 vehicles per day. The noise level measured close to this bridge is correlated with the public data on traffic load and wind speed available by the Washington State Department of Transportation.
Dynamic permeability and tortuosity in weakly consolidated granular media
Authors: Moradi Peyman M. , Kantzas Apostolos
Published: October 2018

Micro-scale rock heterogeneity plays an important role in modifying the seismic response of porous media and must be considered in reservoir studies such as seismic monitoring of fluid flow or interpretation of Stoneley waves. This work focuses on the prediction of dynamic permeability and dynamic tortuosity of granular media at different frequencies from porosity and average grain size data, utilizing numerical simulations. The simulations are conducted through cubic consolidated and unconsolidated digital rock samples of three different rock types, by applying a macroscopic oscillatory pressure gradient to each porous medium and combining fluid flow with solid mechanics to solve the wave propagation problem. The JKD parameter called dynamically connected pore size (Λ) is then predicted for each rock type. We investigate how pore space geometry, cement content and morphology, and matrix heterogeneity can influence the dynamic and geometrical tortuosities.
Broadband numerical simulation of scattering from rough pressure-release and fluid-fluid interfaces
Authors: Olson Derek R. , Lyons Anthony P.
Published: October 2018

The scattered field from the seafloor is often measured using short, broadband pulses, whereas many models for the mean scattered intensity are in the frequency domain. This As higher resolution seafloor mapping systems, i.e., synthetic aperture sonar, become more common, it is important to understand the effects of high resolution on measurements of both the averaged scattered intensity, and the distribution of the envelope of the scattered field. To address this problem, Monte Carlo simulations of the scattered field due to rough interfaces separating two fluids are perform. The integral equation governing the total pressure, the Helmholtz-Kirchhoff integral equation, is numerically solved using the boundary element method. Simulations are performed both in the limit of pressure release, as well as for more realistic sediment sound speed and density parameters. The von-Karman spectrum is used to generate random rough surfaces. Fourier synthesis is used to to generate time domain signals, which are then analyized in terms of the mean energy and amplitude distribution. The dependence of the scattering cross section and scintillation index on signal bandwidth (resolution) is examined. It is found that there is no observable dependence of the scattering cross section on bandwidth, but that there is significant dependence of the scintillation index.
The treatment of the density discontinuity in the split-step Fourier algorithm using the hybrid approach
Authors: Aslan Mustafa
Published: October 2018

Various numerical models generate the solution for the modelling of underwater acoustic wave propagation treat the density discontinuity due to the density change at the interface by different approaches. In the split-step Fourier parabolic equation model, the smoothing function can be applied for the treatment of the density discontinuity, but the phase error is also accumulated with range in the solution. Yevick and Thomson developed the hybrid split-step/finite difference method in which density dependent terms are introduced in the additional operator to be applied by Padé approximation in the algorithm and the phase accuracy is significantly improved using the method. In this work, instead of Padé approximation, various approximations is examined for the density related operator in the split-step Fourier algorithm.
Testing diffusion, Why we need to change the way we do things
Authors: Lenz Richard L.
Published: October 2018

For the last 20 years, different methods have been used in both educational and professional environments to provide test data regarding the performance of diffusers and diffusive products. In many cases, these test methods have defied certain recognized standards common in physics. In other cases, the test methods have been converted to use in test environments which are counter-intuitive to producing the outcomes expected. Additionally, the standard expectation of a single chart producing coefficient results in one or two lines has proven to provide far too little information for the acoustician. This minimal information also does not translate well to actual use in today’s computer design programs. New test developments over the last 7 years by the author, in concert with others, have yielded test data that is both informational and multi-dimensional in nature. Providing both magnitude, polar, phase, and other data, this test, being developed under the guidance of ASTM, avoids the complications inherent in the current standards. This presentation will discuss both current standards and new technologies to overcome the limitations of those standards.
Density in diffusion, quantifying aural quality through testing and listening
Authors: Lenz Richard L. , Davis Chips
Published: October 2018

Diffusion in recording studios and critical listening spaces has been around for well over 30 years. During that time, acousticians and users alike confirm the fact that it makes a difference in the listening space but have a difficult time defining exactly what it is or why they like it. Diffusion test data in the past have been inconclusive as to showing what makes one design more pleasant to the listener than another. This is especially true with in-situ testing. The in-situ testing shown in the presentation will be concentrated on diffusion density or the amount and quality of diffuse energy being reflected. This presentation will also show a set of experiments between different sets of diffusers used as side diffusion in a recording studio. The experiments, using a binaural head and calibrated microphones, will show both test data as well as recorded responses which will be played back to the listening audience. Lab test data, using the proposed ASTM diffusion test under development, will be included to show the diffuser differences from a laboratory perspective. Attendees will be asked to contribute their perspectives to the recording playbacks to further the experiment as to the listener's experience.
Modeling acoustic propagation in an ice-covered environment using a hybrid finite element-ray theory approach
Authors: Simon Blake , Isakson Marcia J.
Published: October 2018

Although models of acoustic propagation in an ice-covered environment have been calculated using only finite elements, ray theory models can cover longer distances and higher frequency ranges much more efficiently. In this study, a hybrid approach is taken by calculating the reflection coefficient of the ice using finite elements over a range of frequencies and angles. These values are then inserted into a ray-theory model. Using this model, a study of the sensitivity of common approximations of the ice cover on acoustic propagation is conducted. For example, the ice can be described simply as a pressure release surface or much more complexly as an elastic body with range and depth geo-acoustic property variations. The hybrid finite element-ray theory model will be verified numerically by comparing it to a full finite element propagation model for appropriate ranges and frequencies. [Work sponsored by ONR, Ocean Acoustics.]
Estimating channel capacity and sonar performance in the changing arctic
Authors: Hines Paul C. , Nams Dainis , Deveau Terry , Kessel Ron , Hamilton Jim , Whitt Christopher , Barclay David R.
Published: October 2018

Underwater acoustic processes including ambient noise, propagation, reverberation, and scattering have been studied for over half a century in the Canadian Arctic. Despite this, realistic predictions of communications and sonar performance have proved challenging due to the complex impact of ice cover on these processes, and the relative scarcity of sound speed profiles and information about the seabed. This challenge has been exacerbated in recent years because the rapid change in environmental conditions is reducing the relevance of many historical records. A key component of the present effort is to extract site specific model inputs from the environmental data contained in the literature, with an informed weighting toward more recent measurements. Site specific modelling was enhanced using inputs from recent year-long ambient noise recordings. Model inputs were also influenced by specific source and receiver hardware being developed for use in future Arctic experiments. In this paper, low frequency sonar and communication performance estimates in the frequency band 20–250 Hz, based on site-specific environmental inputs and this low frequency hardware, are presented for several geographical regions of strategic relevance in the Canadian Arctic.
Low-frequency reverberation estimates using elastic parabolic equation solutions for ice-covered and ice-free Arctic environments
Authors: Frank Scott D. , Ivakin Anatoliy
Published: October 2018

A computational model of reverberation at low frequencies in an ice-covered environment is developed. The model is built on a full-field perturbation approach and includes elastic parabolic equation solutions for the acoustic field and its horizontal and vertical derivatives near water-ice and water-air interfaces. Our previous work demonstrated that average reverberation intensity is sensitive to both elasticity and thickness of the ice at mid-frequencies, where the ice layer thickness is on the order of or larger than both compressional and shear wavelengths. Here we address what happens to the reverberation when ice thickness approaches zero. Reverberation estimates for rough free surface and those from rough ice-water interface with increasing ice layer thickness are compared to determine at what ice thicknesses and acoustic frequencies the long-range reverberation distinguishes between the two cases. To isolate effects of ice thickness, we assume roughness is the same in both environments. Frequencies will be varied from very low, where the ice layer is practically transparent, to moderately low where the presence of the ice becomes noticeable in the reverberation. Numerical examples for reverberation in a typical Arctic environment with upward refracting sound-speed profile are presented and discussed. [Work supported by ONR.]
Underwater bubble low frequency source for Arctic acoustic tomography, navigation, and communication
Authors: Morozov Andrey K. , Webb Douglas C.
Published: October 2018

Arctic acoustic tomography requires a broadband source in the frequency range of 5–100 Hz. To meet this requirement, Teledyne Marine suggests applying a seismic source, recently developed for the Marine Vibrator Joint Industry Project. The source is considered to be less harmful for marine inhabitants and gives more precise and higher resolution imaging of the subsurface formations and structures. The coherent source is based on the application of an underwater, gas filled bubble resonator covered by an elastic membrane. The membrane supports high volume displacement. The sources are not sensitive to cavitation and to coupling effects. The fluid dynamics and acoustics of a spherical resonator are defined by the Rayleigh-Plesset equation. The buoyancy deforms the shape of a real bubble from spherical. The 3D simulation and experiments have shown that a cylindrical form is a practical engineering solution. It performances similar to a spherical bubble, keeps its shape and can be towed with a high speed. The Q-factor of a practical bubble resonator is ~10. Two systems are considered to cover a wide frequency band: a tunable resonator and a broadband multi-resonance system. The research proved that the bubble sound source is a practical solution for a frequency below 100 Hz.
High-resolution wavenumber estimation in ultrasonic guided waves using adaptive array signal processing for bone quality assessment
Authors: Okumura Shigeaki , Nguyen Vu-Hieu , Taki Hirofumi , Haiat Guillaume , Naili Salah , Sato Toru
Published: October 2018

Quantitative ultrasound is a modality that is used to evaluate bone quality. It is considered that the analysis of ultrasound guided wave propagating along cortical bone may be useful for the assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect the elastic parameters of the medium, high-resolution estimation of the wavenumbers at each frequency is important. We report an adaptive array signal processing method with a technique to estimate the numbers of propagation modes at each frequency using information theoretic criteria and the diagonal loading technique. The proposed method estimates the optimal diagonal loading value required for guided wave estimation. We investigate the effectiveness of the proposed method via simple numerical simulations and experiments using a copper plate and a bone-mimicking plate, where the center frequency of the transmit wave was 1.0 MHz. An experimental study of 4 mm thick copper and bone-mimicking plates showed that the proposed method estimated the wavenumbers accurately with estimation errors of less than 4% and a calculation time of less than 0.5 s when using a laptop computer.
Model-based inversion of ultrasonic guided waves for cortical bone properties
Authors: Tran Tho N. , Sacchi Mauricio D. , Ta Dean , Nguyen Vu-Hieu , Le Lawrence H.
Published: October 2018

Axial transmission ultrasonography, which uses a set of transmitting and receiving probes placed on the same waveguide’s surface, shows the potential clinical application for cortical bone quality assessment. In this work, a model-based parameter sweep inversion approach has been developed to estimate the thickness and elastic velocities of the cortex from the dispersive axially-transmitted snapshots. The inversion algorithm is formulated in the frequency-phase velocity (f-c) domain. To solve the inverse problem, i.e., to extract bone properties from ultrasound data, a forward modeling has been developed to simulate the f-c dispersion curves given a bone model. A semi-analytical finite element (SAFE) method is used to compute the dispersion curves for a complex structure of a cortical bone plate coupled with overlying soft tissues. A parameter sweep is used to seek within a range of values an optimized solution with the least misfit. The proposed method optimizes the mismatch between the measured and theoretically calculated dispersion curves with a least-square constraint. Numerical and in-vivo experimental data examples are presented to illustrate the technique’s performance.