bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimized extraction of coherent arrivals from ambient noise correlations in a rapidly fluctuating medium, with an application to passive acoustic tomography
Authors: Woolfe Katherine F. , Sabra Karim G. , Kuperman William A.
Published: October 2015

Ambient noise correlations can be used to estimate Green’s functions for passive monitoring purposes. However, this method traditionally relies on sufficient time-averaging of the noise-correlations to extract coherent arrivals (i.e., Green’s function estimates), and is thus limited by rapid environmental fluctuations occurring on short time scales while the averaging takes place. For instance, based on extrapolating results from a previous study [Woolfe et al., 2015], passive ocean monitoring across basin scales (i.e., between hydrophones separated by ∼1000 km) may require at least 10 weeks of averaging time to extract coherent arrivals; but such an averaging time would be too long to capture some aspects of the mesoscale variability of the ocean. To address this limitation, we will demonstrate with simulation and data that the use of a stochastic search algorithm to correct and track these rapid environmental fluctuations can reduce the required averaging time to extract coherent arrivals from noise correlations in a fluctuating medium. The algorithm optimizes the output of an objective function based on a matched filter that uses a known reference waveform to track a set of weak coherent arrivals buried in noise.
Simulation of ultrasound wave propagation in heterogeneous materials
Authors: Lowe Michael J. , Van Pamel Anton , Huthwaite Peter
Published: October 2015

The simulation of ultrasound waves propagating through heterogeneous materials is useful to a range of applications, including Nondestructive Evaluation (NDE) and materials characterization. In NDE, the challenge is to detect defects within the volume of a component against a background of noise of scattering from the inhomogeneities. In materials characterization, the challenge is to measure properties such as stiffness, texture, and spatial distributions of the inhomogeneities. Until recently, simulation of wave propagation through realistic detailed volumetric representations of heterogeneous materials was infeasible because of the huge computational requirements. However, it has recently become possible to do these kinds of simulations. This talk will show Finite Element model simulations of wave propagation in polycrystalline metals that are representative of the high performance alloys used in electricity power plant components. Validations by examining wave speed, attenuation, and backscatter will be discussed, and example deployments of the models will be presented.
Influence of material heterogeneity on the distortion of a focused ultrasonic beam
Authors: Turner Joseph A. , Arguelles Andrea
Published: October 2015

Recent research associated with elastic wave scattering in heterogeneous materials has shown the importance of the Wigner transform in the formulation of the scattering problem to quantify the transducer beam pattern within the sample. The four-fold Wigner distribution function describes the combined time-frequency, space-wave vector domains simultaneously. To date, this approach has been used successfully to examine the diffusely scattered energy for both pulse-echo and pitch-catch measurement configurations. However, the defocusing effect caused by the scattering has received much less attention than the overall scattering. Here, this problem is posed using a similar approach as the diffuse scattering problem. The energy distribution is shown to be an expansion in terms of the order of the material heterogeneity. Results for the first-order correction from the homogeneous beam pattern are shown with respect to the various parameters of the problem including the frequency, transducer element size, the transducer focus, and the material heterogeneity (here defined in terms of the grain size of a polycrystalline sample). Experimental results of an ultrasonic pulse propagating through a heterogeneous layer will be shown and compared with the model.
High sensitive MEMS directional sound sensor with comb finger capacitor electronic readout
Authors: Wilmott Daniel , Alves Fabio , Karunasiri Gamani
Published: October 2015

The conventional directional sound sensing systems employ an array of spatially separated microphones to achieve directional sensing by monitoring the arrival times and amplitudes of different microphones. However, there are insects such as Ormia ochracea fly that can determine the direction of sound using its miniature-hearing organ much smaller than the wavelength of sound it detects. The fly’s eardrums that are coupled mechanically with separation merely by about 1 mm have remarkable sensitivity to the direction of sound. Our MEMS based sensor, which consists of two 1 mm2 wings connected in the middle, similar to the fly’s hearing system, was designed and fabricated using silicon on insulator (SOI) substrate. The vibration of the wings in response to incident sound at the bending resonance was measured using a laser vibrometer found to be about 1 μm/Pa. For measuring sensor response electronically, comb finger capacitors were integrated on to the wins and the measured output using a MS3110 capacitive to voltage converter was found to be about 25 V/Pa. The fabricated sensors showed cos2q directional response similar to a pressure gradient microphone. The directional response of the sensor was measured down to about 30 dB.
Simulation of surge in the induction system of turbocharged internal combustion engines
Authors: Dehner Rick , Selamet Ahmet , Selamet Emel
Published: October 2015

A computational methodology has been developed to accurately predict the compression system surge instabilities within the induction system of turbocharged internal combustion engines by employing one-dimensional nonlinear gas dynamics. This capability was first developed for a compression system installed on a turbocharger flow stand, in order to isolate the surge physics from the airborne pulsations of engine. Findings from the turbocharger stand model were then utilized to create a separate model of a twin, parallel turbocharged engine. Extensive development was carried out to accurately characterize the wave dynamics behavior of induction system components in terms of transmission loss and flow losses for the individual compressor inlet and outlet ducts. The engine was instrumented to obtain time-resolved measurements for model validation under stable, full-load conditions and during surge instabilities. Simulation results from the turbocharger stand and engine agree well with the experimental data from their corresponding setups, in terms of both the amplitude and frequency of surge oscillations.
Finite element illustrations in the classroom
Authors: Hansen Uwe J.
Published: October 2015

“You hear, you forget. You see, you remember. You do, you understand.” This is Tom Rossing's favorite education quote. Solutions to wave equations generally result in traveling waves. Imposing boundary conditions usually limits these solutions to discrete normal modes. The one dimensional elastic string is an easy, accessible example, illustrated frequently with a long spring. The two dimensional example of a rectangular stiff plate is a little more complex, and the normal modes are often illustrated with Lissajous figures on a plate driven by a shaker. Whille full blown FEA programs are prohibitively expensive, ANSYS has an educational package available to students at nominal cost with sufficient memory to demonstrate normal mode vibrations in moderately complex structures. Normal mode vibrations in a rectangular plate with a number of different boundary conditions will be illustrated.
Fundamentals of acoustics, vibration and sound, underwater acoustics and electroacoustic transduction at UMass Dartmouth
Authors: Brown David A.
Published: October 2015

This paper summarizes the teaching methods and material covered in four introductory graduate classes that are jointly offered as senior technical electives in Electrical Engineering, Mechanical Engineering, and Physics. The possibility of teaching two or three slightly different courses can be done with common lectures by designing different homework, class projects, and examinations for the mechanical engineering and electrical engineering students. Mechanical students are typically well prepared in mechanics and materials while find the use of equivalent electrical circuits more challenging. The reverse is typical for the electrical students. The classes involve many acoustic demonstrations and those are universally appreciated by students with all backgrounds. A number of examples will be presented.
Using sound and music to teach waves
Authors: Ramsey Gordon
Published: October 2015

Sound and music are based on the properties of waves. They are also motivating topics for learning many subjects, from music to physics. The most recent “New Generation Science Standards” (NGSS) requires coverage of waves at all K-12 levels. Studies have shown that active student involvement is important in science education for helping the students understand physical concepts. These facts imply that music and acoustics are perfect avenues for teaching the concepts of waves. Even at the college level, non-science majors can understand how music and physics are related through the understanding of wave phenomena. There are many demonstrations, laboratory investigations and hands-on group activities that can be done at all levels. This paper suggests ways to incorporate sound and music to present waves at the levels of middle school, high school, and beginning college.
Investigation of acoustical spectral analysis to gain a better understanding of tone development in single reed instruments
Authors: Kinzer Charles E. , Cheyne Stanley A. , McDermott Walter C.
Published: October 2015

A series of frequency spectra were measured and analyzed, and the results were used for comparison on a series of tone development exercises for saxophone and clarinet players. The musical exercises were focused on manipulations of the embouchure, oral cavity, and vocal tract as a means for altering the overtone content of the tone produced. The acoustical measurements were used to foster greater understanding on the part of the musicians of the importance of the player's physiology on the production of a musical tone, and help develop the player's ability to alter the tone in an intentional manner. The results of this study will be presented and discussed.
Evaluation of high-level noise exposures for non-military personnel
Authors: Murphy William J. , Zechmann Edward L. , Kardous Chucri A. , Brueck Scott E.
Published: October 2015

Noise-induced hearing loss is often attributed to exposure to high-level impulsive noise exposures from weapons. However, many workers in industries such as mining, construction, manufacturing, and services are exposed to high-level impulsive noise. For instance, construction workers use pneumatic tools such as framing nailers that can produce impulses at levels of 130 dB peak sound pressure level or greater. Miners have exposures to roof bolters and jack-leg drills that produce more of a continuous, but highly impulsive noise. In some areas of manufacturing the exposures include drop forge processes which can create impacts of more than 140 dB. Finally, in the services sector, law enforcement personnel who maintain proficiency with firearms experience the full gamut of small-caliber firearms during training. This paper will examine the noise exposures from recordings that the NIOSH Hearing Loss Prevention Team have collected. The noises will be evaluated with different damage risk criteria for continuous and impulse noise where appropriate.
Role of the kurtosis metric in evaluating hearing trauma from complex noise exposures—From animal experiments to human applications
Authors: Qiu Wei , Zhang Meibian , Hamernik Roger
Published: October 2015

A number of animal experiments and epidemiologic studies in humans have demonstrated that current noise standard underestimated hearing trauma by complex noise. While energy and exposure duration are necessary metrics they are not sufficient to evaluate the hearing hazard from complex noise exposure. The temporal distribution of energy is an important factor in evaluating NIHL. Kurtosis incorporates in a single metric all the temporal variables known to affect hearing (i.e., peak, inter-peak interval, and transient duration histogram) that makes kurtosis as one of the candidate metrics. Our previous animal studies show that both kurtosis and energy are necessary to evaluate the hazard posed to hearing by a complex noise exposure. In this study, we focus on how to use the knowledge from animal model into humans. Methods are presented to solve the following questions: (1) How to calculate the kurtosis? (2) What is the relation between kurtosis and the hearing trauma? (3) How to extract a single number from the distribution of kurtosis that would best correlate with noise trauma in real industrial noise environments? Human data study shows that the kurtosis metric may be a reasonable candidate for evaluating the risk of hearing trauma complex noise exposures.
Recent Japanese research activities on flow induced vibration and noise
Authors: Kaneko Shigehiko
Published: October 2015

In this presentation, recent Japanese research activity on Flow Induced Vibration and Noise mainly done by Kaneko laboratory, Department of Mechanical Engineering, the University of Tokyo, will be presented. Topics cover vortex induced vibration related to Japanese fast breeder reactor Monju thermo-well in line oscillation, sloshing and sloshing damper in connection with the liquid separator designed for Floating Production, Storage and Offloading (FPSO) system, galloping and galloping damper used for cable stayed bridges, combustion oscillation of gas turbine combustor taking account of chemical reaction process, and pipeline acoustics leading to acoustic fatigue. In the end, 30 years of history of data base group activity in Japan Society of Mechanical Engineers (JSME) will be introduced.
Using flow-induced vibrations for structural health monitoring of high-speed naval ships
Authors: Sabra Karim G.
Published: October 2015

It has been demonstrated theoretically and experimentally that an estimate of the impulse (or structural) response between two receivers can be obtained from the long-time average of the cross-correlation of diffuse vibrations (or ambient noise) recorded at these two receivers in various environments and frequency ranges of interest: ultrasonics, underwater acoustics, seismology, and structural health monitoring. Indeed, those estimated impulse responses result from the cumulated contributions over time of random vibrations (e.g., as created by flow-induced vibrations) traveling along the test structure and being recorded by both. Hence, this technique provides a means for structural health monitoring using only the ambient structure-borne noise (e.g., generated by flow-induce vibrations) only, without the use of active sources. We will review work conducted using (1) high-frequency random vibration (100 Hz–5 kHz) data induced by turbulent boundary layer pressure fluctuations and measured on a hydrofoil and a plate at the Navy’s William B. Morgan Large Cavitation Channel. (2) Low frequency random vibration data (1 Hz–50 Hz) collected on high-speed naval ships during at-sea operations were strong wave impact loading took place. [Work sponsored by ONR.]
Wave dispersion in highly deformable, fluid-filled structures: Numerical and experimental study of the role of solid deformation and inertia
Authors: Kurzeja Patrick , Bertoldi Katia
Published: October 2015

The application and scientific interpretation of wave measurements in fluid-filled structures strongly depend on the frequency regime of interest. This includes, for example, absorption bands, inverse calculation of elastic moduli, and non-destructive crack localization. The wave properties significantly differ between the low-frequency regime (where viscous forces couple fluid and solid) and the high-frequency regime (where inertia forces allow for multiple decoupled wave modes with individual speeds and attenuation). Thus, knowledge of the separative transition frequency is crucial for a reliable prediction, but respective approximations like Biot’s characteristic frequency still originate from stiff structures. Soft materials such as biological tissues or synthetic materials are neglected regarding their high deformability. Hence, this presentation demonstrates the change of wave properties from low to high frequencies in soft, fluid-filled structures and highlights the influence of solid deformability and inertia. In particular, it will present:an experimental design to control stiffness and density of a single porous structure by buckling mechanisms with negligible influence on permeability; microscale simulations to identify the underlying wave modes; and peculiarities occurring in soft fluid-filled structures such as significant dispersion of the P1-wave speed.
Experimental validation of a three-dimensional finite-amplitude nonlinear continuum model of phonation
Authors: Hosnieh Farahani Mehrdad , Zhang Zhaoyan
Published: October 2015

Due to the complex nature of the phonation process, simplification assumptions (e.g., reduced flow model, small strain vocal fold deformation) are often made in phonation models. The validity of these assumption is largely unknown because the overall behavior of these phonation models often has not been validated against experiment. In this study, a three-dimensional finite-amplitude nonlinear continuum model of the vocal folds is developed and compared to results from experiments using a self-oscillating physical model of the vocal folds. The simulations are based on a nonlinear finite element analysis, whereby large displacement and material nonlinearity are taken into account. The vocal-fold model is coupled with a reduced-order flow solver based on Bernoulli equation. Preliminary results show that the model is able to qualitatively reproduce experimental observations regarding phonation threshold and typical vocal fold vibration patterns. [Work supported by NIH.]
Acoustic correlates of velar flutter associated with nasal emission during /s/ in children with velopharyngeal dysfunction
Authors: Eshghi Marziye , Eshghi Mohammad , Zajac David J.
Published: October 2015

Velar flutter can accompany obligatory nasal air emission in children with cleft palate. It usually occurs as a result of air passing through a partially closed velopharyngeal port that creates turbulence and tissue vibration due to aerodynamic-elastic forces. Nasal air emission can also occur without flutter. In this case, the velopharyngeal port is relatively large and turbulence is generated at the anterior nasal valve without flutter. In this study we applied auto-correlation to discriminate velar flutter from non-flutter nasal air emission. Three children with nasal turbulence and velar flutter and three children with nasal turbulence without flutter were recorded using the oral and nasal microphones of the Nasometer during production of /si/. Nasal emission of the /s/ sound captured by the nasal microphone was isolated and the auto-correlation functions of the signals were graphed using MATLAB. Results showed that nasal emissions with velar flutter have auto-correlation functions with periodic/quasi-periodic patterns. However, the auto-correlation functions of the non-flutter nasal emissions showed noisy fluctuations without periodic oscillations. Findings revealed that auto-correlation function can be used clinically as an acoustic technique to detect tissue vibration accompanied with nasal air emission.
Combining gestures and vocalizations to imitate sounds
Authors: Scurto Hugo , Lemaitre Guillaume , Françoise Jules , Voisin Frédéric , Bevilacqua Frédéric , Susini Patrick
Published: October 2015

Communicating about sounds is a difficult task without a technical language, and naïve speakers often rely on different kinds of non-linguistic vocalizations and body gestures (Lemaitre et al. 2014). Previous work has independently studied how effectively people describe sounds with gestures or vocalizations (Caramiaux, 2014, Lemaitre and Rocchesso, 2014). However, speech communication studies suggest a more intimate link between the two processes (Kendon, 2004). Our study thus focused on the combination of manual gestures and non-speech vocalizations in the communication of sounds. We first collected a large database of vocal and gestural imitations of a variety of sounds (audio, video, and motion sensor data). Qualitative analysis of gestural strategies resulted in three hypotheses: (1) voice is more effective than gesture for communicating rhythmic information, (2) textural aspects are communicated with shaky gestures, and (3) concurrent streams of sound events can be split between gestures and voice. These hypotheses were validated in a second experiment in which 20 participants imitated 25 specifically synthesized sounds: rhythmic noise bursts, granular textures, and layered streams. Statistical analyses compared acoustics features of synthesized sounds, vocal features, and a set of novel gestural features based on a wavelet representation of the acceleration data.
Effect of depression on syllabic rate of speech
Authors: Sahu Saurabh , Espy-Wilson Carol
Published: October 2015

In this paper, we are comparing different methods to measure syllable rate of speech. Basically our method counts the number of vowels and divides it by the duration of speech. We use the energy content in 640–2800 Hz and 2000–3000 Hz to eliminate nasals and glides. Energy content in 0–400 Hz as well as pitch information and helps eliminate the unvoiced fricatives. We compare our method with Jong et al. (Behavior research methods. 2009; 41 (2): 385–390.) who wrote a Pratt script and with another method that estimates the syllable rate from peak modulation rate of speech. We have seen that the latter measure tracks the changes in HAMD scores and therefore seems sensitive enough to measure changes in the degree of depression. We will determine if these other methods will show the same sensitivity
Doppler discrimination of a constant velocity scatterer at depth in shallow water
Authors: Camara Christopher , Anchieta David , Gendron Paul J. , Mahrajan Praswish
Published: October 2015

Doppler as a discriminant for a shallow water moving rigid scatterer from a single element receiver is considered here. A mono-static source-receiver configuration emits a single tone to ensonify a moving object. Inference regarding the depth and speed of the moving object are sought from the amplitude and Doppler of the direct arrival and the surface interacting arrival. Computation of the full posterior probability distribution of the returned amplitudes and frequencies given the received waveform and the prior distribution on target depth is made by Markov Chain Monte Carlo sampling. A Gibbs sampler is employed to construct the posterior joint density of all parameters. Conditional and marginal densities of the amplitudes are analytically tractable while those of the frequencies are made with an importance sampling approach. Confidence intervals are computed and employed to address depth discrimination.
Context recognition on smartphones by categorizing extracted features from acoustic and other sensor data
Authors: Tateishi Miho
Published: October 2015

This work presents a method of context recognition on smartphones using several built-in sensors. This system is developed for the Android. The three sensors are a microphone, an accelerometer, and a light sensor, which are correlated with human senses or movement. Context recognition is a method of being aware of the user’s context or contiguous environment. In existing systems, raw time series data are directly used for the recognition. Our system aims to define data categories, which are connected with contexts, by extracting features from time series data. These features are made up of processed signals from each sensor. In particular, acoustic data turns into several different features; volume, spectrum average, peak spectrum appearance ratio, and correlation of these signals over a defined period of time. With acceleration and light features, it can classify similar contexts in the same category. For example, riding the train appears in one discreet category. Another category exemplifies the situation in a library, PC room, or laboratory which can be described as the “quiet” work place. As a part of automatic context awareness, features are formed hierarchical structure in order to make this method efficient.
Stable QAM development with less BER on convergence time-compression type Q-learning for mass audio signal transmission
Authors: Okada Kazuhide
Published: October 2015

This paper presents method which protects the temporary hang-up on the communication line and sustains the demodulation of the clear audible signal at the receiver, when the mass sound data is sent from the transmitter. QAM is one of the digital modulation technology, mapping the modulating signal not only toward the phase but also toward the amplitude on Q-I constellation, derived from QPSK. This modulation can pack larger data in the fixed period than QPSK. But once the communication path is exposed by stuff jitter or random jitter, the quantization error on its coordinate occurs, which means coordinate axes often subtly rotate with returning to the original position. In order to minimize such quantization errors on demodulation, Q-learning as one of Reinforcement Learning was used in this study. In the design of the feedback system comprehending the agent and the environment, the angle of the reverse vibration of the upper each axis for the quick restoring to the normal quantization becomes an action at. And the reward rt is the relative baud rate, while the status st is BER, as I/F between Agent and the environment. The Quantity of a state action combination Q(st, at) was updated as the index which measures the value of actions, with the Quantity computation steps decreased by TTD (Truncated Temporal Difference) and Log-time overlooking at Q(st, at) in the training process of the experiment. The degree of control on coordinate's axes vibrations triggered by injected jitter was evaluated by the visible decrease in BER.
A study of variance of spectral content and sound radiation in timpani player
Authors: Leonard Brett , Shinbara Scott
Published: October 2015

Timpani, although limited in pitch material, have the ability to produce many subtle colors, exceeding most other membranophones. One of the most notable characteristics of timpani is the perceptual “bloom” of the sound as distance is increased with the drum. Timpanists spend many hours working on control of these sounds and the bloom through application of intricate mallet technique and striking location. Anecdotal evidence of these differences is passed down through generations of teachers and students, but very little objective data exists about the actual sound of the drums, and the variations that occur between players. This study endeavors to reveal the objective differences between players and techniques, particularly as it relates to the “bloom” of the sound as you move away from the drum. Control of this directivity and expansion of perceived sound at a distance may be the single most important factor in the quality of a timpanist’s sound. Measurements are taken at different distances and locations around the drum for more than 15 different subjects, revealing a complex and interesting spectral patter radiating from the drum.
A multinational comparison of measurement methods and metrics in acoustic standards and guidelines for healthcare environments
Authors: Madaras Gary
Published: October 2015

The field of architectural acoustics is in the initial stage of a paradigm shift when it comes to quantifying sound fields in healthcare facilities. A growing number of practitioners and researchers are questioning whether existing acoustic measurement methods and metrics relate well to patient perception of quietness or medical outcomes. A multinational overview will be provided of various acoustic standards and guidelines for healthcare facilities. Acoustic measurement methods and metrics from different countries are compared to identify commonalities and discrepancies. An update is provided on the progress of the World Health Organization's revision of their 1999 Community Noise Guidelines, particularly the hospital noise section. Information is compiled and presented in order to begin the process of possibly defining new acoustic measurement methods and metrics that relate more strongly to patient perception of quietness and medical outcomes.
How to identify and control noise that could cost your hospital money
Authors: Mundell Joe
Published: October 2015

Noise levels in hospitals are problematic. Today, patient opinions on noise, because of HCAHPS, determine hospital reimbursement. It's critical for hospitals to reduce noise levels in their facilities or face reductions in reimbursement. Patient perceptions of noise in hospitals is difficult to accurately measure and determine root cause. Many hospitals are implementing programs to address noise, but very few are making these decisions based on systematic sound monitoring data within their facility. Sound monitoring equipment installed in hospitals can accurately measure and identify both sources and patterns of noise in hospital. Real-time and historical sound data can help inform changes needed. We compare historic sound data from our experience monitoring sound levels in NICU’s and compare findings to improving sound levels throughout hospital. We discuss how visual alarming alone is insufficient to maintain long term improvements. We also discuss the use of measuring “sound events” to idenitfy ture source of noise disturbances. We argue that hospitals that measure “sound events” can systematically improve their HCAHPS scores. In conclusion, sound recording equipment within hospitals will provide actionable data. This data can be used to implement structural and procedural improvements allowing hospitals to maximize reimbursement and improve outcomes.
Variations of fin whale's 20 Hz calls in the Gulf of California
Authors: Bonilla-Garzón Andrea , Romero Vivas Eduardo , Urbán-Ramírez Jorge
Published: October 2015

The fin whale's song has been broadly described in different areas of the world, and it is well characterized, being the spectrogram the main representation used to extract descriptions and measures. Males produce the 20 Hz calls, which consist of a down-swept pulse series (18–30 Hz) with a fundamental frequency of 20 Hz. Each pulse has duration of approximately 1 s, with aggrupation patterns of singlet, doublets and triplets. A time analysis of calls recorded by a High-frequency Acoustic Recording Packages (HARPs) localized in Punta Pescadero and Bahía de los Ángeles, south and north of the Gulf of California, México in the 2004 through 2008, revealed variations of the pulse that are not easily discernable through the use of the spectrogram. Results of the preliminary analysis of 100 calls are presented. Regional differences in duration, structure, and shape found could indicate a geographical separation of population units of fin whales in the Gulf of California.
Mice ultrasonic detection and localization in laboratory environment
Authors: Sinelnikov Yegor , Sutin Alexander , Salloum Hady , Sedunov Nikolay , Sedunov Alexander , Masters David
Published: October 2015

The acoustic detection and localization of mice movement by monitoring their ultrasonic vocalization has been demonstrated in laboratory environment using ultrasonic system with three microphones that provides recording of ultrasound up to 120 kHz. The tests were approved by Stony Brook University Institutional Animal Care and Use Committee protocol. Signals were recorded in a set of discrete sequences over several hours. The locomotor activity was characterized by durations up to 3000 ms and wide spectral content, while the syllable vocalization constituted shorter 200 ms events, with a set of identifiable up and down frequency modulated tones between 3 kHz and 55 kHz. The Time Difference of Arrival (TDOA) to various microphones was calculated using cross correlation method and was applied for estimation for mice location. Mice are among the invasive species that have a potential of crossing borders of United States unnoticed in containers. This study demonstrates the feasibility of using acoustic methods for detection of potential rodent intrusions. [This work was sponsored by DHS S&T.]
Relating click-evoked auditory brainstem response waveforms to hearing loss in the bottlenose dolphin (Tursiops truncatus)
Authors: Gasser Rutledge Krysta L. , Houser Dorian S. , Finneran James F.
Published: October 2015

Hearing sensitivity in captive Atlantic bottlenose dolphins was assessed using a portable electrophysiologic data collection system, a transducer attached to the pan region of the mandible, and non-invasive recording electrodes. The auditory steady-state response (ASSR) was evoked using sinusoidal amplitude-modulated tones at half octave steps from 20–160 kHz and utilized to determine the upper frequency limit of hearing (i.e., the frequency at which threshold was ≤ 120 dB re 1 μPa). An auditory brainstem response (ABR) was then recorded to a moderate-amplitude click (peak-equivalent sound pressure level of 122 dB re 1 μPa) and examined to determine if relationships existed between the upper frequency limit of hearing and the waveform characteristics of the click-evoked ABR. The ASSR and click-evoked ABR were measured in 6 bottlenose dolphins with varying hearing sensitivity and frequency range of hearing. A significant relationship existed between click-evoked ABR wave amplitudes and the upper frequency limit of hearing. Test times for assessment using frequency-specific ASSR and click-evoked ABR were ∼45 minutes and 1 minute, respectively. With further definition of normative data, measurement of click-evoked ABRs could form the basis of an expedited electrophysiologic method for hearing screening in marine mammals.
Field calibration—Distributed vehicles and sensors and the use of their acoustic communications transmissions for probing the medium
Authors: Hursky Paul
Published: October 2015

Underwater vehicles and float of various kinds are often used to provide distributed sensing or monitoring of the medium in which they are deployed. Such cooperating platforms typically communicate with each other using high-frequency, broadband acoustic communications. Such transmissions may provide much more information than is carried in their acomms payload, if they are used as ranging signals for navigation and probing signals for imaging the medium they travel through. We have collected data to explore this concept during two experiments, Makai 2005 in Hawaii and Radar 2007 in Portugal. We have previously shown how channel estimates gleaned from high-frequency probe signals from a moving platform and received on a receiving sensor array could be used to improve localization at lower frequency. We expand upon this previous work to demonstrate how such channel estimates at the relatively sparse locations where probes were transmitted by a vehicle can be interpolated to flesh out the channel impulse response throughout the localization search space. We also discuss how such transmissions can be used in aid of clock synchronization and navigation.
Optimized excitation for nonlinear wave propagation in complex media: From biomedical acoustic imaging to nondestructive testing of cultural heritage
Authors: Dos Santos Serge , Lints Martin , Poirot Nathalie , Salupere Andrus
Published: October 2015

The interaction between an acoustic wave and a complex media has an increase interest for both nondestructive testing (NDT) applications and for biomedical ultrasound. Today, new optimized excitations are generated thanks to the analysis of symmetry properties of the system such as reciprocity, nonlinear time reversal (TR) and other pulse-inverted (PI) techniques. Generalized TR based NEWS (Nonlinear Elastic Wave Spectroscopy) methods and their associate symmetry skeleton will be taken as an example. Among these family of “pulse coded excitation,” solitonic coding constitutes a new scheme in the sense that solitary waves are the best candidates for pulse propagation in nonlinear and layered media, such as tooth or skin. As another application of mixing properties in a wide frequency range, new broadband techniques are needed in the domain of the preservation of cultural heritage. The analysis of the composition of the stones is one of the key parameters in the study of aging historic buildings. The use of TR-NEWS based analysis combined with a FTIR-based system has shown a specific property of the tuffeau limestone where damaged sample contains calcite. In both domains, aging properties of complex medium are extracted thanks to the use of enhanced nonlinear signal processing tools.
Ultrasound molecular imaging of heterogeneous tumors to guide therapeutic ultrasound
Authors: Padilla Frederic , Helbert Alexandre , Tardy Isabelle , Lafon Cyril , Chapelon Jean-Yves , von Wronski Mathew , Tranquart François , Hyvelin Jean-Marc
Published: October 2015

Propagation through heterogeneous tissues may hamper the ability to correctly focus ultrasound, especially when targeting a tumor for drug delivery applications. To solve this issue, we propose to use ultrasound molecular imaging (USMI) for treatment planning of drug delivery triggered by focused ultrasound. In a model of orthotopic rat prostate tumor having heterogeneous B-mode appearance, we show that tumor extend can be precisely delineated with USMI targeting VEGFR-2 receptors. High intensity ultrasound bursts (Peak negative pressure −15 MPa) are then delivered within this delineated 3D volume to trigger the release of liposomal-encapsulated chemotherapy, by local initiation of inertial cavitation. Real time imaging show that cavitation is indeed restricted to the targeted area. In the animal group receiving both chemotherapy and cavitational ultrasound, a potentiation of the therapeutic effect of the drug is clearly observed. This study demonstrates experimentally that USMI is an effective imaging method to characterize heterogeneous tissues and to guide therapeutic ultrasound.
Modified transfer function with a phase rotation parameter for ultrasound longitudinal waves in cancelous bone
Authors: Taki Hirofumi , Nagatani Yoshiki , Matsukawa Mami , Mizuno Katsunori , Sato Toru , Kanai Hiroshi
Published: October 2015

The through-transmission ultrasound signal in cancelous bone consists of two longitudinal waves, called the fast and slow waves. The conventional propagation model assumes that the wavefront of an ultrasound wave passing through a bone specimen is flat and that each wave arrives simultaneously at all the points on a transducer surface. To compensate for the waveform change caused by the effect of the uneven wavefront received at a flat transducer, we propose a new transfer function modified with a phase rotation parameter. We also propose a fast decomposition method that requires only 5 seconds using a laptop personal computer. The proposed decomposition method using the modified transfer function succeeded to separate the two waves and characterize each of them accurately, where the normalized residual intensity power was less than −20 dB in the experimental study when the bone specimen thickness was from 6 to 15 mm. In the simulation study, the normalized residual power was less than −20 dB when the specimen thickness was from 3 to 8 mm. These results show that the transfer function with a phase rotation parameter is valid and that the proposed decomposition method has a great potential to provide good indicators of osteoporosis in real-time.
Optimization of wave surface for planar loudspeaker array reproduction
Authors: Ando Akio , Yamoto Takuya , Yamabayashi Daisuke
Published: October 2015

Over the past few decades, a considerable number of studies have been made on the sound field reproduction by loudspeaker array. It is well known that the reproduced sound field suffers from various errors caused by the finite and discrete loudspeaker array. The error by the finite array is a so-called truncation error, which is a kind of diffraction effect resulting from the absence of secondary sources outside the finite area. Such error sometimes brings the degradation of reproduced wave surface and frequency response. In this study, the weighting coefficient vector for loudspeaker input is introduced, meaning that the input signal fed into each loudspeaker is multiplied by an element of the vector. The input signal is calculated according to the Rayleigh I integral. The vector is solved such that the integration of square error between the ideal and synthesized wave surface over the target area is minimized under the constraint that all elements of the vector have non-negative values. Various optimization methods are compared in this problem. It is shown that the shape of wave surface is improved by the optimization and the improvement of wave surface also brings the improvement of frequency response.
Nonlinear acoustic response of stand-off tubes used in acoustic pressure measurements—Part I: Experimental study
Authors: Rehl Anthony , Quinlan John M. , Scarborough David , Zinn Ben
Published: October 2015

Rocket engine combustion instabilities, which lead to rapid engine failure through enhanced heat transfer rates and high-cycle fatigue, continue to be the most serious concern facing engine designers. Experimental testing and pressure measurements remains the best approach to determine the susceptibility of an engine design to acoustically coupled combustion instabilities. But, the harsh, high-temperature environment requires that pressure transducers be remotely mounted to the engine’s main chamber using “sense-tubes,” thereby creating an area-contraction at the connection point between the sense-tube and combustor. Preliminary measurements showed large discrepancies between sense-tube measured and engine acoustic pressure amplitudes. To elucidate these discrepancies, this experimental study measured the nonlinear response of the area-contraction/sense-tube geometry. Specifically, the sense-tube was attached to a two-microphone impedance tube, allowing the measurement of the acoustic impedance of the combined area-contraction and sense-tube; the acoustic pressure was also measured at the sense-tube termination, allowing the the direct measurement of the frequency response function. Measurements were performed over a range of frequencies, area-contraction ratios, acoustic velocity amplitudes, and sense-tube length-to-diameter ratios. These measurements reveal that the acoustic response of the sense-tube was highly nonlinear—even for low amplitude forcing.
Calculating total daily noise exposure using aircrew flight equipment noise attenuation and fight segment noise data
Authors: Gross Daniel A.
Published: October 2015

The workplace of military aircrew is louder and more varied than most industrial environments. In the recent revision of MIL-STD-1474E, Noise Limits, octave band level design limits for helicopters have been replaced by a broader requirement based on noise exposure at the ear. This change brings 1474E into alignment with DoD hearing conservation policies which require that total daily noise exposure does not exceed an Leq of 85 dBA during an 8 hour period. Although these polices also require use of hearing protection whenever levels exceed 85 dBA, there is currently little written guidance for how to use hearing protector attenuation data to estimate exposure at the ear over the course of a typical mission profile. This paper will explain how attenuation data for flight helmets and communication headsets has been used by the Naval Air Systems Command to estimate noise exposure for crew and passengers in various types of aircraft.
Fluctuation-driven attenuation and dispersion of sound near the critical points of fluids
Authors: Gillis Keith A. , Moldover Michael R.
Published: October 2015

We discuss the extraordinary growth in the attenuation of sound αλ and in the dispersion in the speed of sound c, which occurs near all liquid-vapor critical points. The attenuation and dispersion have been measured over 5 orders of magnitude in frequency. Remarkably, the data collapse onto universal, theoretically predicted curves. The theory considers equilibrium density fluctuations near the critical point where the fluctuations are large compared with the particle spacing. These density fluctuations have a distribution of sizes characterized by the correlation length ξ and a distribution of lifetimes characterized by the relaxation time τ. As the critical point is approached, ξ and τ diverge with the universal power laws ξ ∝ r−0.63 and τ ∝ r−1.93, where r is a measure of the distance from the critical point. [At the critical density ρc, r ≡ (T − Tc)/Tc.] In the low-frequency limit (ωτ ≪ 1), the attenuation grows as αλ ∝ r−1.93 and the speed of sound approaches zero as c ∝ r0.055. When ωτ ≫ 1, αλ approaches a maximum, non-universal limit and strong dispersion is present. Low-frequency sound waves reach the condition ωτ = 1 closer to Tc and deeper into the asymptotic critical regime than do high-frequency sound waves. In Earth's gravity, we show that stirring a near-critical fluid reduces stratification and enables measurements closer to the critical point. We compare the attenuation and dispersion for pure fluids near the liquid-vapor critical point with that of binary liquid mixtures near the consolute point.
Temperature and pressure effects on elastic properties of lead magnesium niobate-lead titanate relaxorferroelectric material
Authors: Tennakoon Sumudu P. , Gladden Joseph R.
Published: October 2015

Lead magnesium niobate—lead titanate (PMN-PT) exhibits exceptional electromechanical properties, considered as a highly efficient transduction material for vibration energy harvesting and acoustic sensing applications. It is reported in the literature that the PMN-PT undergoes structural phase transitions with changes in temperature and the chemical composition. We seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with chemical composition close to the morphotropic phase boundary (MPB) was used in a resonant ultrasound spectroscopy (RUS) study performed in the temperature range from room temperature to 773 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of the PMN-PT material is observed at the temperatures below 400 K. Strong stiffening is observed in the temperature range of 400 K–673 K, followed by a gradual softening at higher temperatures. With the varying pressure, we observed an increased pressure sensitivity of elastic properties of the PMN-PT material that can be localized to the temperature regime where the strong stiffening is observed. As time allows, the behavior of PMN-PT upon cooling below room temperature will also be discussed.