bluuebunny/crossref_metadata_2025 huggingface dataset:
Beam patterns of the dolphin demonstrate task-dependent dynamics
Authors: Houser Dorian S. , Talmadge Lois , Starkhammar Josefin , Moore Partick
Published: November 2016

The echolocation beam of the bottlenose dolphin was first carefully described by Au and colleagues (1978)[“Propagation of Atlantic bottlenose dolphin echolocation signals,” J. Acoust. Soc. Am. 64, 411-422] using various hydrophone array configurations and targets located in front of the dolphin and along its longitudinal axis. Measured beams were described as vertically elevated with mean vertical and horizontal 3-dB beamwidths of ~10°. The experimental paradigm was later augmented with denser hydrophone arrays, greater spatial coverage of the acoustic field, and the training of target detection with targets presented to the left or right of the dolphin’s longitudinal axis. Utilizing two dolphins, beam steering capabilities and beamwidth control were demonstrated. The two dolphins steered the axis of the echolocation beam up to 18° and 28° in the horizontal plane. Horizontal beamwidths were bimodally distributed in one dolphin, with peaks at 16° and 26°. The other dolphin had a unimodal distribution of beamwidths (peak at ~25°), likely reflecting a learned strategy for the off-axis detection task. The use of dense hydrophone arrays and challenging echolocation tasks continue to build on the work of Au and colleagues, who provided a paradigm that has greatly contributed to our understanding of dolphin biosonar.
Using “phantom” echoes to study dolphin biosonar
Authors: Finneran James J. , Mulsow Jason , Branstetter Brian K. , Houser Dorian S. , Moore Patrick W.
Published: November 2016

Biosonar studies have greatly benefited from the use of electronic, or “phantom,” echoes. In this paradigm, amplitude and timing information are extracted from an emitted biosonar pulse, then a delayed signal is broadcast to the animal to appear as an echo from a more distant target. Phantom echoes provide unique capabilities for studying biosonar, since they allow echo features such as amplitude and delay to be independently manipulated. In 1987, Whit Au and colleagues described a phantom echo system for use with marine mammals [Au et al. (1987). “Phantom electronic target for dolphin sonar research,” J. Acoust. Soc. Am. 82, 711-713]. In this system, delayed broadcasts of one or more replicas of the dolphin click were triggered by dolphin click emissions. A major improvement in phantom echo systems was later described by Aubauer and Au (1998) [“Phantom echo generation: A new technique for investigating dolphin echolocation,” J. Acoust. Soc. Am. 104, 1165-1170], who simulated the impulse response of a physical target, rather than broadcasting a stereotyped waveform. In this talk, phantom echo system concepts are briefly presented and several recent applications of phantom echo systems—inspired by the work of Aubauer and Au—are discussed. [Work supported by ONR.]
Acoustic methods of pest detection in agricultural shipments
Authors: Sutin Alexander , Flynn Timothy , Sedunov Nikolay , Salloum Hady , Sedunov Alexander , Masters David
Published: November 2016

Stevens Institute of Technology, in cooperation with the DHS Science and Technology Directorate and the U.S. Customs and Border Protection, has been investigating engineering solutions to augment the current inspection process at ports of entry in an effort to minimize the threat posed by invasive species. Stevens has built several sensitive acoustic systems for detection of tiny acoustic/vibrational signals produced by moving insects and tested them in a Laredo, TX port of entry. The system for detection of insects in vegetables and herbs uses a soundproofed case where boxes filled with vegetables or herbs were placed during test. For wood boring insects, sensitive custom-made accelerometers were built. Special algorithms for detection of events connected with insect movement and separating them from the ambient noise were developed. Tests conducted demonstrated reliable detection of Copitarsia larva in a large box of vegetables. Smaller insects similar to Khapra beetles were clearly detected in a relatively small volume of grains (2-4 lbs). [This work was supported by DHS’s S&T Directorate.]
Acoustic cam on a remote operated vehicle for coral reef soundscape recording
Authors: Romero-Vivas Eduardo , Gutiérrez-Jagüey Joaquín , Bustamante Omar A. , Villa Médina Francisco , Beristain Sergio , Von Borstel Fernando D.
Published: November 2016

Although the broadband high level sounds of snapping shrimps dominate the soundscape of a coral reef, the spatial, spectral, and temporal variations due to biotic and abiotic factors are indicators of the health of these vulnerable environments; for instance, reefs become louder during new moons of the wet season, when many larval organisms settle, or tends to go quiet as animals abandon them when conditions become less favorable. Moreover, the soundscape is able to provide information on the reef benthic composition and has been identified as a possible driver of reef population dynamics. To study this particular environment, a Remote Operated Vehicle (openROV) is being used to visually identify the biota associated with a shallow coral reef near a major port in La Paz, Mexico. An acoustic linear array has been incorporated, providing directional sound recording capabilities to capture better space variability of the coral soundscape. By combining visual and acoustical clues in an acoustic cam, it is also feasible to associate fish species and acoustic signals. A preliminary assessment of the design for monitoring a shallow coral reef is presented, along with a comparison with traditional diving surveys.
A novel approach to measurement of underwater sound levels in a dangerous tidal fjord using a miniature self-contained acoustic recorder
Authors: Burgess William C. , McGuire Tamara L.
Published: November 2016

Recent plans for highway construction along the shore of Turnagain Arm, Alaska, raised concerns about acoustic impact on the critically endangered Cook Inlet subpopulation of beluga whales (Delphinapterus leucas). Evaluation of possible impact required estimates of normal background sound levels. However, as a shallow fjord with profound (9-m mean) tides, hazardous currents, tidal bores, and quicksand-like tidal flats, Turnagain Arm has historically defied most vessel operations and thwarted vessel-based sound measurements. In August 2014, the first documented acoustic measurements in Turnagain Arm of which we are aware took place using a novel technique based on a miniature, self-contained acoustic recorder developed as a marine-mammal tag (Acousonde™, Greeneridge Sciences, Inc.). The recorder’s small size allowed it to be suspended from a motorized buoy and towed up to 80 m from shore. Measurements took place off a point known as Windy Corner at high and low tide as well as near maximum flood and ebb current. Data showed Turnagain Arm to be quieter than expected, with broadband (40 Hz to 9.3 kHz) sound pressure levels as low as 74 dB re 1 μPa and below a 125-dB provisional regulatory assumption. [Work supported by Alaska Department of Transportation and Public Facilities.]
Application of coastal acoustic tomography to Lake Biwa, Japan
Authors: Wells John C. , Aota Yasuaki , Auger Guillaume , Kaneko Arata , Goda Noriaki
Published: November 2016

We will provide an update on continuing development of coastal acoustic tomography (CAT) in Lake Biwa, Japan, which will provide monitoring data for assimilation into a prototype “nowcast system” for the flow and temperature fields in the lake. Employing 5 kHz transducers, we have achieved a number of successful CAT tests since August 2014 in the North Basin, which has a mean depth of 41 meters. These were performed under both unstratified and stratified conditions, at transmission distances up to 10 km, and included a continuous 2-month deployment in homogenized winter conditions. Due to weaker mixing than coastal seas, stratification-induced refraction in lakes is stronger than normally encountered in CAT. We believe these to be the first successful tests of acoustic tomography ever reported for a lake. Received signals were remarkably different between the nearshore station with bottom depth about 9 m, and offshore of Takeshima island with bottom depths around 35 m. Current efforts aim to improve SNR for reception offshore of Takeshima island.
Feasibility of geoacoustic tomography in shallow water
Authors: Turgut Altan , Schindall Jeffrey A. , Means Steven L.
Published: November 2016

In shallow water, spatial and temporal variability of the water column often restricts accurate estimations of bottom properties from long-range acoustic propagation data. Two recent shallow-water experiments, conducted at a sandy site on the New Jersey Shelf and a muddy site on the New England Shelf, showed 5-10 dB acoustic transmission-loss differences between two sites. The New Jersey Shelf experiment was conducted during May 2015 and The New England Shelf experiment was conducted during November 2015, representing summer and winter propagation conditions, respectively. Acoustic modal analysis and pulse-decay tomography methods were used to map the geoacoustic variability of each site covering a 40 km by 40 km area. Both numerical simulations and the New England Shelf experimental results showed that geoacustic variability can be measured by geoacoustic tomography. Tomographic results from the New Jersey Shelf sites showed less geoacoustic variability that may be due to the presence of a harder bottom. Effects of the water-column variability on the geoacoustic tomography results are also discussed for summer and winter environments. [Work supported by the ONR.]
Rip current tomography based on reciprocal sound transmissions using reflective waves
Authors: Nakano Iwao , Ishida Hiroshi , Deguchi Ichiro
Published: November 2016

In order to monitor the occurrence of rip current in beaches, an acoustic measurement system for rip currents based on passive reciprocal sound transmissions using reflective waves was designed and developed. The offshore current velocity V is given by V = C02/L*(t21-t12)/2 where C0 is sound speed, L is the distance between the transducers, t21 is travel time at onshore transmission, and t12 is travel time at offshore transmission. The typical components of the measurement system consisted of one modified dual-frequency sounder, two broad-band acoustic transducers, six sound reflectors, and a data acquisition network. The frequency, source level, and transmission interval of transmitted signal was 50 kHz, 1 kW (max), and 2 s, respectively. The typical monitoring area is 30 m wide and 90 m long, and the depth is 1 m. This system simply required the precise position measurement of two transducers and sound reflectors. The sound speed was determined by the direct travel times between the transducers. When the field tests were conducted at Uradome Beach in Tottori Prefecture of Japan in September of 2014, the phases of sound signals were so stable to allow the automatic peak and/or phase tracking. The obtained and reconstructed velocity data were consistent with those by EM current meters.
Reliable acoustic path tomography at Aloha Cable Observatory
Authors: Varamo Vincent J. , Howe Bruce
Published: November 2016

Using a mobile ship platform (R/V Kilo Moana) with an acoustic source transmitting to a fixed bottom hydrophone at the ALOHA Cabled Observatory (ACO), we are investigating the feasibility of “RAP tomography” (Reliable Acoustic Path). This will allow the spatial mapping of the path integrated sound speed (temperature) over a 60 km diameter “teacup” volume of the ocean. This can be considered an extension of an inverted echosounder (from a vertical to near horizontal path) combined with the precise positioning and timing of seafloor geodesy, where noise for the latter, sound speed, is our signal. As a first step, transmissions were sent from a 4x4 array of transducers at 3.5 kHz when the vessel approached and departed from ACO. The measured travel times were compared with estimated travel times based on CTD measurements. As the next step, we use new instrumentation to ensure exact time of acoustic transmission and to test user-generated signals (LFM sweeps and M-sequences) to improve the time of arrival resolution. Also, to increase the amount of shallow angle energy for the longer ranges, only one transducer with a broader beamwidth will be used. Results from an August 2016 experiment will be presented. [Work supported by ONR.]
Repeatability and reproducibility of ultrasonic attenuation coefficient and backscatter coefficient measures in adults with non-alcoholic fatty liver disease
Authors: Han Aiguo , Andre Michael P. , Loomba Rohit , Sirlin Claude B. , Erdman John W. , O'Brien W. D.
Published: November 2016

The attenuation coefficient (AC) and backscatter coefficient (BSC) are two promising quantitative ultrasound biomarkers, yet their repeatability and reproducibility (R&R) have never been assessed in human subjects. This study assesses R&R of the AC and BSC in 30 adults with suspected non-alcoholic fatty liver disease (NAFLD), a wide liver fat content range, age range of 28-71, using a Siemens S3000 scanner. Each subject had two consecutive scans between which the subject was repositioned. In each trial, the 4C1 and 6C1HD transducers were used for multiple B-mode/RF acquisitions of the right lobe of the liver. Then, a reference phantom was scanned using the same transducer and machine settings. Two sonographers each scanned 15 patients independently. Two fields of interest (FOIs; with and without visible blood vessels) were drawn for each image. AC and BSC were estimated within the FOIs. AC and log-transformed BSC mean values within 2.6-3.0 MHz were used for the R&R analysis based on an unweighted sums of squares ANOVA approach. The variabilities of inter-trial, inter-image, inter-FOI, and inter-transducer conditions were found to be lower than the inter-patient variability. The inter-transducer variability was the lowest among all analyzed variables. [Support: NIH R01DK106419.]
Quantitative ultrasound and the pancreas
Authors: Miller Rita J. , Han Aiguo , Erdman John W. , Wallig Matthew A. , O'Brien William D.
Published: November 2016

Pancreatitis is inflammation of the pancreas. Cerulein-induced pancreatitis in animal models can cause a significant increase in pancreatic enzymes in blood, as well as interstitial edema and inflammatory cell infiltration in the pancreas. This degree of pancreatitis is mild; all animals survive the induction of pancreatitis and resolves within ~6 days after induction, making this an excellent model to study the attenuation coefficient (AC: dB/cm-MHz) and backscatter coefficient (BSC: 1/cm-sr) of the pancreas temporally. The edematous stroma and shrinkage and dedifferentiation of acinar cells, has certain similarities with the morphology in some forms of pancreatic carcinoma. The pancreas’ AC and BSC (20-50 MHz) were estimated in vivo and ex vivo at baseline (before cerulein injections) and at 24 h, 48 h and 72 h after cerulein injections in Sprague-Dawley rats (N = 24). AC and BSC showed the same trends whereby (relative to baseline values) the 24-h AC decreased ~0.3 dB/cm-MHz and BSC decreased ~1-2 dB with AC and BSC progressively approaching the baseline values at 48 h and 72 h, suggesting that as a function of time, the AC and BSC are reflecting a change in the pancreas back to baseline conditions. [Support: NIH Grant R37EB002641.]
Numerical evaluation of time-domain Green's functions for space-fractional wave equations
Authors: Zhao Xiaofeng , McGough Robert
Published: November 2016

Ultrasound attenuation in soft tissue follows a power law as a function of the ultrasound frequency. Several different models for the power law attenuation of medical ultrasound have been developed using fractional calculus, where each contains one or more time- or space-fractional derivatives. For certain time-fractional models, exact and approximate time-domain Green's functions have been derived and evaluated numerically, but a similar analysis has not yet been performed on the space-fractional models. To address this deficiency, time-domain Green's functions are numerically calculated here for two space-fractional models, namely the Chen-Holm and Treeby-Cox space-fractional wave equations. Numerical results are computed for both of these in breast and liver with power law exponents of 1.5 and 1.139, respectively. The results show that these two space-fractional wave equations are causal everywhere. Away from the origin, the time-domain Green's function for the dispersive Treeby-Cox space-fractional wave equation is very similar to the time-domain Green's functions calculated for the corresponding time-fractional wave equations, but the time-domain Green's function for the nondispersive Chen-Holm space-fractional wave equation is quite different. To highlight the similarities and differences between these, time-domain Green's functions are compared and evaluated at different distances for both breast and liver.
High-frequency ultrasound study of angiogenesis in zebra fish embryos
Authors: Sanjinez Dolly A. , Cadet Michaelle A. , Wagner Garrett , Doyle Timothy E.
Published: November 2016

Cancer and other prevalent diseases such as heart disease, rheumatoid arthritis, stroke, and diabetic retinopathy are directly associated with either an increase or decrease in levels of angiogenesis in the body. High-frequency (HF) ultrasound (10-100 MHz) is particularly sensitive to small vascular structures that are close in size to the ultrasound wavelength (15-150 μm). The ability to rapidly determine the degree of vascularization in the development of small animals in vivo would provide a useful characterization tool for the study of a variety of diseases. The objective of this study was to determine if HF ultrasonic measurements could identify microscopic vessel formation that occurs during the development of zebra fish embryos within 1-3 days post-fertilization (dpf). Casper and P53 Nacre zebra fish embryos were provided by the Stewart Lab at the Huntsman Cancer Institute (Salt Lake City, Utah). The embryos were placed in 12-well cell culture plates, embedded in agarose and egg water, and immobilized with tricaine. Embryos were positioned on their lateral side and tested 1-2 dpf using 50-MHz pulse-echo measurements. The results show that the number of peaks in the ultrasonic spectra correlate with embryo development and may provide a quantitative assessment method for angiogenesis.
A fast signal processing technique for characterizing Lamb wave propagation in viscoelastic cortical long bones using one transmitter and two receivers
Authors: Okumura Shigeaki , Nguyen Vu H. , Taki Hirofumi , Sato Toru
Published: November 2016

Axial transmission technique is useful in assessing bone quality. Most conventional techniques require multiple transmitters and receivers. Decreasing the number of elements and computational complexity are desired for low-cost diagnosis. We propose a technique that characterizes the Lamb wave using one transmitter and two receivers. Because the transfer function of the Lamb wave is mainly determined by the longitudinal wave velocity (LWV), shear wave velocity (SWV), and bone thickness, these parameters may be determined in a fitting procedure using the transfer function. The number of combinations of these parameters is enormous, and we thus select the candidates for these parameters using spatial domain interferometry. The method estimates the phase velocity of zero-th order anti-symmetric mode. We applied the proposed method to numerical simulation data generated by the semi-analytical finite element method. We employed a viscoelastic plate with LWV, SWV, and thickness of 2120 m/s, 4430 m/s, and 1.0 mm, respectively. The estimation errors of proposed method for SWV, LWV, and thickness were within 5.0 m/s, 15 m/s, and 0.05 mm, respectively. The fitting residue was −18 dB. The calculation time was 3.6 s. These results demonstrate the high potential of the proposed method in the low-cost diagnosis of bone quality.
Simulation study of ultrasound propagation in anisotropic and heterogeneous cortical bone model
Authors: Takano Koki , Nagatani Yoshiki , Matsukawa Mami
Published: November 2016

Ultrasound propagation in the heterogeneous long cortical bone was studied. First, ring shaped specimens were obtained from the mid-shaft of a bovine radius. The longitudinal wave velocity distribution of each specimen was measured in the MHz range. Then, using the bilinear interpolation and the piecewise cubic Hermite interpolating method, a 3D axial velocity model was created with the resolution of 40 μm. Assuming the uniaxial anisotropy of the bone,1,2 distributions of all elastic moduli of the initial 3D heterogeneous model were estimated. At the surface of the model, the elastic moduli were smaller than those of the inside parts. Elastic finite-difference time-domain method was used to simulate axial ultrasonic wave propagation in the model. The initial model and the thinner model, where the inner part of the cortical bone was removed, were compared. The wave front of the first arriving signal (FAS) depended on the heterogeneity in the model. However, the effects of removal on the arrival time of the FAS was not obvious. 1. Y. Yamato, et al. (2008). Calcif. Tissue Int. 82, 162-169. 2. T. Nakatsuji, et al. (2011). Jpn. J. Appl. Phys. 50, 07HF18.
In vivo radius bone evaluation of women in their late teens by two wave apparatus
Authors: Matsukawa Mami , Nakanishi Shoko , Mano Isao , Horii Kaoru , Yoneda Yutaro , Umemura Shiori , Ozaki Etsuko
Published: November 2016

Making use of the fast and slow wave phenomenon in cancellous bone, an ultrasonic bone measurement system, LD-100 (OYO electric),1 has been developed and is now commercially available in Japan. From the measurements of fast, slow, and echo waves, the system gives us cancellous bone density (mg/cm3), cancellous bone elasticity (GPa), and the cortical thickness (mm). The measurement area is the distal 5.5 % site of the radius of the non-dominant hand. In this study, the system was modified for the small radius of teenagers using annular array elements. Under the permission of the ethics committee at Doshisha university, radius bones of 111 high school students were measured (15-17 years old, female). The mean values of cortical thickness of the students were 93.7—97.7% of the young adult mean (YAM). The cancellous bone densities were 82.6—94.0% of YAM. The standard deviations of these values were higher than the deviations of YAM. These data possibly indicate that the growth of radius bone depends on the site and the outer cortical shell grows fast. For further discussions, more data should be necessary. 1. H. Sai, et al., Osteoporos Int. (2010) 21, 1781-1790
Acoustical estimation of endosseous implant stability: Finite element modeling and experimental validation
Authors: Nguyen Vu-Hieu , Vayron Romain , Haiat Guillaume
Published: November 2016

Various endosseous implants are widely used in orthopedic and dental surgeries. However, failures are observed, which may have dramatic consequences and are often due to a loss of implant stability. The aim of this presentation is to describe two acoustical methods developed to assess the stability of different implants. First, a quantitative ultrasound method was used to determine the stability of dental implants. A monoelement 10 MHz transducer is screwed into the implant and the signal is processed to obtain an indicator. The method was first validated in implants embedded in biomaterials used as bone substitutes, then in vitro and eventually in vivo by comparison with histology. A 3D FEM was developed to optimize the device conception and carry out sensitivity studies. Second, an impact hammer was used in order to investigate whether the AC implant primary stability can be evaluated using such approach. The method was first validated in vitro and in cadaveric experiments. The results showed that an indicator based on the impact momentum may be correlated to the implant pull-out force. A 3D FEM was also developed to analyze and better understand experimental results. This study shows the potential of acoustical methods to assess non-invasively implant stability.
Improvement of signal to noise ratio at outdoor listing position by sound emission timing control over the Internet for mass notification system
Authors: Chisaki Yoshifumi , Onoguchi Taira
Published: November 2016

Mass notification system has multiple nodes, where a node consists of some loudspeakers, in order to cover wide service area. Sound signal is emitted from grouped nodes simultaneously in general. Thus, the simultaneous emission from grouped nodes sometimes makes overlapping of sound signals at a listening point in the service area. Since it affects speech intelligibility, reduction of overlapping is a quite important issue not only for emergency but also reduction of wasteful signal power on mass notification system. Recently,global positioning device and network devices, such as 3G/LTE, become reasonable to be equipped to a node of mass notification system. Therefore, it makes easy to control emission timing at each node intelligently. Development of an intelligent algorithm for mass notification is introduced and a part of the algorithm is implemented on a single board computer, Raspberry PI. Performance on signal to noise ration at all the listing points in service area is presented and discuss it with other evaluation methods.
Speech intelligibility prediction method using machine learning for outdoor public address systems
Authors: Kobayashi Yosuke , Ohta Kengo , Kondo Kazuhiro , Sakamoto Shuichi
Published: November 2016

Subjective speech intelligibility assessment is important for the development of outdoor public address system. However, as this assessment is difficult in many cases, we propose an objective speech intelligibility evaluation system that includes a machine learning technique. In this talk, we have proved a subjective evaluation and objective prediction of speech intelligibility using the outdoor public address systems at 10 locations in Sendai City, where impulse responses were recorded after the Great East Japan Earthquake. First, the results of the subjective intelligibility evaluation by different test word lists with the same sound field conditions showed that the root mean squared error (RMSE) was very small, not exceeding 7.0%. Next, we generated the intelligibility prediction model trained with true/false results of 22 subjects using the support vector machine (SVM). This prediction model extracted the feature vector, using the ITU-T P.563 speech quality feature set of the test speech signal. We evaluated the predictive performance of the prediction model using data that was not used in training, and the RMSE obtained was 4.0%. This result was shown to be highly accurate with a value even less than the subject experiment result.
Relationship between speech intelligibility and objective measures in sound fields with a discrete long-path echo
Authors: Sato Hayato , Morimoto Masayuki , Miyagawa Yusuke , Suzuki Yôiti
Published: November 2016

The outdoor public address system is one of the important methods to notify evacuation information in disaster situations. However, when speech announcements are simultaneously radiated from a number of dispersedly located loudspeakers, speech intelligibility decreases because of temporal or spatial segregation of speech streams, just like a long-path echo in large closed spaces. The present study is focusing on relationship between speech intelligibility and spatial characteristics of long-path echo. Useful-detrimental ratio (U50) was tested to predict speech intelligibility scores in sound fields with a discrete long-path echo. A noteworthy feature of U50 is that all energy of long-path echo is explicitly counted as detrimental energy. The results of intelligibility tests demonstrated that the feature led to lower intelligibility predictions, that is, predictions on the safe side. Meanwhile, the prediction errors increased when the difference between interaural differences for the direct sound and the long-path echo. The extended U50 to consider binaural effects referring to the concept of binaural speech transmission index [van Wijingaarden and Drullman, J. Acoust. Soc. Am. 123, 4514-4523 (2008)] showed a higher correlation with the intelligibility scores relative to the original U50.
Formulation of sound propagation and scattering in forests as a radiative transfer theory
Authors: Ostashev Vladimir E. , Wilson David K.
Published: November 2016

Several approaches have been used in the literature to characterize sound scattering in forests. In this presentation, an approach based on the radiative transfer equation (RTE) is considered. Although the RTE has been used for other types of scattering problems, it is new to forest acoustics. The RTE is an integro-differential equation for the specific intensity, which is the average power flux density within a unit solid angle in a certain direction of propagation. It describes the processes of sound scattering and absorption by discrete scatterers such as tree trunks, branches, and leaves. RTE is applied to sound propagation in a four-layer forest model (ground, trunks, canopy, and open air). The trunk layer is modelled with vertical cylinders, while the canopy layer is modeled by spheres. The scattering amplitudes and total scattering cross sections of these scatterers are identified. At the interface of the trunk layer and ground, the specific intensity is specularly reflected. Although the RTE is based on a phenomenological theory for propagation of intensities, the mutual coherence function of the sound field (which can be obtained from a Helmholtz equation and the multiple scattering theory) may be expressed in terms of the specific intensity.
Ubiquitous monitoring of infrasound for early detection of events relevant to disaster
Authors: Nishimura Ryouichi , Owada Yasunori , Taira Shinichi
Published: November 2016

A terrestrial event resulting in natural disaster often radiates infrasound when it occurs. Similar phenomenon can be observed in extreme weathers as well. Infrasound travels through the air approximately at the speed of sound and it is faster than traveling of physical kinetic energy which may sometimes bring about a disastrous impact on human lives. Therefore, early detection and source localization of such events are promising for hazard prevention and damage mitigation. To achieve this purpose, coverage of the land is important in terms of celerity and spatial precision, but facilities suitable for monitoring infrasound are not common. In Japan, one monitoring station, IS30, is in operation under Comprehensive Nuclear-Test-Ban Treaty (CTBT) and a few microbalrometer arrays are experimentally set up by Japan Weather Association (JWA) on some parts of Japanese coast. A group of University of Hawaii developed an app for capturing infrasound on iOS devices, and the captured data can be utilized for further analysis. We developed a similar app for Android and deployed smartphones running it on a wireless network to collect information for 24 hours a day stably. Combining the information gathered, we tried to estimate the source signal and its location.
Realtime and interactive tools for speech and hearing science education
Authors: Kawahara Hideki
Published: November 2016

Recent advances of computational power and software foundations make it possible to introduce interactive and realtime tools in speech and hearing science education with relatively low cost. The tool, SparkNG (Speech Production and Auditory perception Research Kernel, Next Generation) consists of four applications. They are (a) real-time FFT analyzer with interactive spectrogram, (b) real-time display of FFT spectrogram (narrow-band and wide-band) and auditory (ERB, Bark and 1/3 octave) spectrogram, (c) real-time vocal tract shape visualizer, and (d) interactive speech production simulator enabling vocal tract shape and transfer function manipulation with aliasing-free L-F model (Kawahara et al., 2015 APSIPA) manipulation. The tool is useful for teachers to demonstrate underlying concepts in an intuitive and attractive manner. It also is useful for researchers to check their ideas quickly. MATLAB source codes of the constituent functions are open to everyone. A compiled MATLAB license-free version is also available. [This work was supported by JSPS KAKENHI Grant Number JP16K12464.]
Three-dimensional sound-field visualization system using head mounted display and stereo camera
Authors: Inoue Atsuto , Ikeda Yusuke , Yatabe Kohei , Oikawa Yasuhiro
Published: November 2016

Visualization of a sound field helps us to intuitively understand various acoustic phenomena in sound design and education. The most straightforward method is to overlap the measured data onto a photographic image. However, in order to understand an entire three-dimensional (3D) sound field by using a conventional two-dimensional screen, it is necessary to move a camera and measure repeatedly. On the other hand, the augmented reality (AR) techniques such as an optical head mounted display (OHMD) have been rapidly developed. In this study, we propose a sound field visualization system using an OHMD and a handheld four-point microphone. This system calculates sound intensity from the four sound signals in real time. Then, the sound intensity distribution is depicted as arrows in the 3D display. The position and angle of the microphones and user’s head are acquired via AR markers and a gyro sensor of the OHMD. The system realizes simple and effective visualization of 3D sound field information from the various directions and positions of view. For the experiments, the sound field generated by a two-way loudspeaker was visualized. The results suggested that the proposed system can present information of the field in easily recognizable manner.
A modular guitar for teaching musical acoustics
Authors: Marozeau Jeremy
Published: November 2016

In order to keep students activated in a course on musical acoustics, they were asked to build a modular guitar, designed to be updated throughout the course. In the first stage, dedicated to the physics of strings, a guitar was made out of three strings attached to a long piece of wood. The students measured the effect of the place of plucking on the mode of the vibrations of the strings. The second stage was dedicated to the acoustic resonances. Using a laser cutter, the students built a wooden box that was coupled to their guitar using straps. New acoustical measurements were made to study the effect of the shape of the resonator on the spectrum of the sound. In the third stage, as the different tuning systems were learned, the students built a fingerboard with the appropriated positions of the frets. In the last stage, the students have implemented some digital effects and tested them on their guitar using a piezo-electrical pickup. As nothing was glued, the students were able to easily change each part of the guitar (resonator, sound hole, fret positions, microphone, …) in order to experience their direct effect and their interactions.
Effectiveness of personal noise exposure measurement in the noisy workplace
Authors: Takezawa Koko , Inoue Jinro , Mori Koki , Horie Seichi , Kawanami Syoko
Published: November 2016

In Japan, the Working Environment Measurement Standards require employers to measure noise of working environment by two kinds of methods using a sound level meter (SLM) once every 6 months. A-Sampling method is to be measured equivalent continuous sound level for at least 10 min. B-Sampling method is to be performed close to workers at times when the sound level appeared highest. We perform the risk assessment based on the values of the field measurement. In the East Japan Railway Company, workers move around several workshops and use hand tools. Therefore, it is difficult to estimate the personal noise exposure using only an SLM. To compare dose measurement with the Japanese field measurement, we carried out dose measurements for inspection or repair workers using a Personal Noise Dose Meter (Type 4448; Brüel & Kjær). The results revealed that all sound levels using a dosimeter were less than 85 dBA, while the sound levels using an SLM were more than 90 dBA. In this case, the risk can be overestimated. Thus, we conclude that the Working Environment Measurement Standards should adopt the dose measurement.
Noise reduction ratings of active noise cancellation headsets
Authors: Murphy William J. , Gallagher Hilary L. , McKinley Richard L.
Published: November 2016

The recent promulgation of the MIL-STD 1474 E, “Design Criteria Standard Noise Limits,” combines data from the Real Ear Attenuation at Threshold (REAT) and the Microphone in Real Ear (MIRE) measurements to estimate the noise reduction rating of active noise cancellation (ANC) hearing protection devices. This paper will examine the American National Standards Institute standards, S12.6, S12.42, and S12.68 to assess the performance of four aviation headsets measured with REAT and MIRE methods. We will compare the protection estimates for different noises with the Noise Reduction Statistic for A-weighting (NRSA), Noise Reduction Statistic for Graphical (NRSG), and Octave Band rating methods. The NRSG method provides an efficient and accurate alternative to the Octave Band rating method. In the International Standards Organization, the ISO 4869 standard part 6 is under development to measure the attenuation of ANC protectors. Comparison with the proposed ISO 4869-6 standard will be conducted.
An objective, efficient auditory situation awareness test battery for advanced hearing protectors and tactical communications and protective systems (TCAPS): DRILCOM (detection-recognition/identification-localization-communication)
Authors: Casali John G. , Lee Kichol
Published: November 2016

An objective, computer-controlled test battery was developed for measuring the effects of hearing protection devices (HPDs) and TCAPS, on auditory situational awareness (ASA). Four independent ASA tasks with military relevance were tested: Detection-Recognition/Identification-Localization-Communication (DRILCOM). Detection employed threshold-shift with seven 1/3-octave bands, an AK-47 burst, and rifle cocking. Detection signals emanated from in front of the subject (0 degrees), or at 90, 180, or 270 degrees, to evaluate directionality. The Recognition/Identification task employed 36 signals combined in triads, wherein one “target” sound from 0 or 90 degrees had to be identified, at S/N ratios of -10, 0, and + 10. Localization employed a dissonant pure tone chord, spanning 104-7880 Hz, which provided interaural time and interaural level cuing. Localization entailed 360-degrees of azimuth in 30-degree increments, and 30-degrees in frontal elevation, at a S/N of + 10. The Communications task, addressing pass-through communications, utilized QuickSIN messages from 4 directions. In a proof-of-concept experiment on 10 subjects, 2 in-ear TCAPS, 1 earmuff TCAPS, a passive Combat Arms Earplug in “open” setting, and an EB-15LE™ electronic earplug were tested, as well as the open ear. DRILCOM demonstrated sensitivity to performance differences among devices and the open ear, as well as diagnosticity to within-device performance differences across different ASA tasks. The results have implication for selection and deployment of TCAPS and HPDs.
Standard methods for measuring the effects of special hearing protectors on auditory performance
Authors: McKinley Richard L. , Gallagher Hilary L. , Thompson Eric R.
Published: November 2016

Traditional hearing protectors attenuate noise via passive and or active technology. The advent of special hearing protectors, i.e., those that provide communications capability, ambient listening/situation awareness function, and/or level dependent attenuation of continuous and/or impulsive noise, has generated additional needs for performance measurement and characterization. ANSI Standards, representing the consensus of the U.S. scientific community, provide accurate, reliable, and repeatable methods for measuring performance. Current standards address the measurement of passive noise attenuation, active and level dependent insertion loss, impulsive peak insertion loss, and speech intelligibility. However, a need exists for a standard measurement method/s to characterize sound localization ability and auditory situation awareness. The presentation will address the application of current standards as well as a framework for a new standard describing three possible methods to measure sound localization performance and auditory situation awareness.
Evaluation of extended-wear earplug technology as a transparent hearing-protection device
Authors: Brungart Douglas S. , Sherlock LaGuinn , Iyer Nandini , McKenna Elizabeth A. , Thompson Eric R. , Zaleski Ashley C.
Published: November 2016

One of the greatest challenges in hearing conservation is providing adequate protection for those listeners who spend most of their time in quiet environments, but are occasionally exposed to high levels of noise that occur at unpredictable times. A classic example of this problem occurs for dismounted soldiers, who rely heavily on their natural hearing acuity to detect threats and opportunities on the battlefield but always face the risk of becoming engaged in a dangerously noisy firefight with little or no warning. One emerging technology that might have application in this domain is the extended-wear hearing aid, which is capable of remaining deep in the ear canal for weeks or months before being removed. Preliminary results suggest that the extended wear earplug can provide protection from blast or continuous noise that is comparable to a conventional earplug or muff, and that it can provide detection and localization performance comparable to that achieved with the open ear. Its form factor also makes it more likely to be compatible with headsets, radios, and personal protective equipment than traditional earplug or earmuff devices. The potential benefits and limitations of the extended-wear earplug as a hearing protector will be discussed. [Work supported by MRMC Grant W81XWH-14-1-0254; The opinions and assertions presented are the private views of the authors and are not to be construed as official or as necessarily reflecting the views of the Department of Defense.]
Effect of a level-dependent hearing protector on detection thresholds, perceived urgency, and localization performance of reverse alarms
Authors: Laroche Chantal , Giguère Christian , Vaillancourt Véronique , Shmigol Evgenia , Rahnama Mani , Gravel Anne , Vaillancourt Tanya , Chiasson Jérémie , Rozon-Gauthier Véronique
Published: November 2016

Previous studies have shown that perception of warning signals in noisy workplaces can be compromised when wearing conventional hearing protectors. Level-dependent hearing protectors have been developed to increase environmental awareness and, by extension, to improve worker safety. A set of studies was conducted to assess the potential benefits of a level-dependent hearing protector operating in its passive and active modes, in quiet and in noise, for a range of listeners with normal hearing listening to reverse alarms. As expected, the detection of reverse alarms in quiet was improved in the active mode compared to the passive mode, but no significant benefit was found in noise. The active mode of the device only marginally helped to restore the sense of urgency conveyed by back-up alarms in noise, which was largely affected by passive attenuation.The localization of reverse alarms was slightly worse when wearing the device compared to unprotected listening, and was not improved in the active mode compared to the passive mode. In summary, when choosing a hearing protector to ensure adequate perception of reverse alarms, for example, different psychoacoustic tasks must be considered, also keeping in mind that level-dependent hearing protection does not necessarily restore performance to unprotected targets.
Tuning to a particular acoustic whispering-gallery mode in the GHz range
Authors: Mezil Sylvain , Fujita Kentaro , Tomoda Montonobu , Clark Matt , Wright Oliver B. , Matsuda Osamu
Published: November 2016

Surface Acoustic Waves (SAWs) generated with sub-picosecond light pulses are commonly used in non-destructive testing. The absorption of pump light by the medium generates SAWs that are detected by delayed probe light pulses. The spatiotemporal evolution of the SAWs can be imaged by scanning the position and time delay of the focused probe light pulses. Commonly used setups show two main constraints: the pump light is focused to a circular spot that generates SAWs in all directions, which does not allow control of directionality, and the laser repetition rate frep limits accessible frequencies to nfrep(n = 1,2,…). In the case of laser excitation and detection of whispering-gallery modes (WGM) on a disc, only certain frequencies are detectable, and counter-propagating modes cannot be separately excited. Here, we overcome these limitations in experimental GHz SAW imaging of WGMs. To access arbitrary frequencies, we periodically modulate in intensity of the pump and probe beams and make use of both in-phase and in-quadrature lock-in detection [1]-[3]. To generate WGMs propagating in a single direction, we make use of a spatial light modulator and computer-generated holograms. These new results extend the possibilities of SAW imaging by allowing fine control of excited surface acoustic modes. [1] S. Kaneko, M. Tomoda, and O. Matsuda, AIP Adv. 4, 017124 (2014); [2] O. Matsuda et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Control 62, 584-595 (2015); [3] S. Mezil et al., Opt. Lett., 40, 2157-2160 (2015).
Acoustic study of Wigner crystal melting in n-GaAs/AlGaAs at high magnetic fields
Authors: Suslov Alexey , Drichko Irina , Smirnov Ivan , Pfeiffer Loren , West Ken , Galperin Yuri
Published: November 2016

We have measured absorption and velocity of surface acoustic waves (SAWs) in high-mobility samples n-GaAs/AlGaAs in magnetic fields (12–18) T (filling factors ν = 0.18–0.125) at temperatures T = (40–340) K and SAW frequencies f = (30–300) MHz. From the measurement data, the complex AC conductance, σAC(ω) ≡ σ1(ω)—iσ2(ω) and its dependences on frequency, temperature, and the amplitude of the SAW-induced electric field were found. We conclude that in the studied interval of the magnetic field and at T < 200 mK, the electronic systems forms pinned Wigner crystal, the so-called Wigner glass. The estimate of the correlation (Larkin) length of the Wigner glass is about 3 μm, which is much larger than both the distance between the electrons and the magnetic length in the studied field range. At some temperature Tm, the temperature dependences of both components of the complex conductance get substantially changed: from the dielectric behavior at T < Tm to the metallic one at T > Tm. We ascribed this change of the conduction mechanism to melting of the Wigner crystal and studied the dependence of the so-defined melting temperature on the electron filling factor. [This work was supported by RFBR 14-02-00232, NSF Cooperative Agreement DMR-1157490, the State of Florida, the Gordon and Betty Moore Foundation through the EPiQS initiative Grant GBMF4420, and the NSF MRSEC Grant DMR-1420541.]