bluuebunny/crossref_metadata_2025 huggingface dataset:
An introduction to the applications and bubble dynamics of the combustive sound source
Authors: McNeese Andrew R. , Wilson Preston S. , Muir Thomas G.
Published: November 2016

The combustive sound source (CSS) is a versatile underwater sound source with an adjustable output amplitude used in underwater acoustics experiments. Unlike typical impulsive acoustic sources, CSS can maintain a wide bandwidth at low amplitude and can be tuned to operate in a band of interest. The CSS can be used as a source for low-frequency sediment characterization, array calibration, TL measurements, and when deployed on the bottom can produce seismic interface waves. In addition to stationary deployments in the water column, CSS can be deployed in a tow body. The CSS consists of a submersible combustion chamber, open to the water, which is filled with a combustive mixture that is ignited via spark. Upon ignition, the combustive mixture is converted into high temperature combustion byproducts which expand and ultimately collapse back to smaller volume than before ignition. Acoustic pulses are radiated by the bubble activity. Although the far-field acoustic propagation is generally assumed to be linear, the inherent nature of the bubble growth and collapse is a nonlinear phenomenon. Discussion will focus on the latest CSS design including functionality and acoustic output, as well as the nonlinearity of the bubble dynamics associated with a CSS event.
Modes of targets in water excited and identified using the radiation pressure of modulated focused ultrasound
Authors: Daniel Timothy D. , Marston Philip L. , Kiersteins Ivars , Abawi Ahmad T.
Published: November 2016

Previously, we excited low frequency flexural modes of a circular plate in water using modulated radiation pressure generated by focused ultrasound [J. Acoust. Soc. Am. 137, 2439 (2015)]. This effect is distinct from excitations associated with parametric array sonar in that static deformation can be produced by radiation pressure as has been measured and analyzed for bubbles [T. J. Asaki and P. L. Marston, J. Acoust. Soc. Am. 97, 2138-2143 (1995)]. In our experiments, solid targets are suspended by lines or supported on sand and the modulated ultrasound is focused on the target’s surface. Target sound emissions were recorded and a laser vibrometer was used to measure the surface velocity of the target to give the magnitude of the target response. An improved high-power focused transducer allows us to drive modes of larger more-realistic target models. By varying the modulation frequency and monitoring the target response, resonant frequencies of the target can be found. By scanning the point-like driving force, the target mode shapes can be measured and compared to finite element models. [Work supported by the Office of Naval Research.]
Measurement of the structural waves in a mine and low frequency tomographic imaging using a parametric sonar
Authors: Wyber Ron J. , Feguson Brian G.
Published: November 2016

To investigate the structural response of mines at low frequencies a parametric sonar with a horizontal beamwidth of about 5 degrees and a bandwidth from 1 kHz to 10 kHz was used. Advantage was taken of the wide bandwidth to obtain a high resolution in the impulse response measurements of the targets by transmitting a linear period modulated pulse and applying pulse compression and a Kaiser Bessel shading to the reflected signal. Over the frequency response of the measurements structural waves are excited in the mines which clearly identify them as man-made targets. The structural waves observed include flexural waves propagating around the body of the mine which provide information on the mine construction. Results are presented showing the variation in the structural response as the targets are rotated through 360 degrees. Tomographic imaging is applied to the measured impulse response and it is shown that by gating out the structural waves clear images of the mines can be obtained even at these low frequencies. This provides the opportunity to image buried targets, particularly in muddy areas where burial is most likely. Profiling measurements in Sydney Harbour are presented showing the variation in the bottom penetration with the sediment type.
Parametric sources—From theory to commercial products
Authors: Dybedal Johnny
Published: November 2016

The interest for underwater application of nonlinear acoustic began in the late 1950s and early 1960s with Westervelts idea of using nonlinear effects to generate low frequency sound beams with high directivity; the parametric source. This idea got a lot of attention during the 1960s and 1970s from various scientific institutions. An early experiment with a parametric source was performed by ELAB at the University of Trondheim and Simrad in 1977. In the early 1980s, Bentech started the design of a towed, combined mapping system for bathymetry and detection of buried pipelines. The idea was to do detection while moving along the pipeline, which required a sub-bottom profiler with steerable beams with high directivity. Due to limited space for transducer, a parametric source was the logical choice. A prototype of the parametric sub-bottom profiler was finished in the late 1980s. Following the prototype, the system was commercialized and additional versions were developed covering applications from shallow water, high resolution work to full ocean depth, high penetration work. Today KONGSBERG is a world leading supplier of parametric sub-bottom profilers.
Vocal effort and fatigue in virtual room acoustics
Authors: Bottalico Pasquale , Cantor Cutiva Lady C. , Hunter Eric J.
Published: November 2016

Vocal effort is a physiological entity that accounts for changes in voice production as vocal loading increases, which can be quantified in terms of Sound Pressure Level (SPL). It may have implications on potential vocal fatigue risk factors. This study investigates how vocal effort is affected by room acoustics. The changes in the acoustic conditions were artificially manipulated. Thirty-nine subjects were recorded while reading a text, 15 out of them used a conversational style while 24 were instructed to read as if they were in a classroom full of children. Each subject was asked to read in three different reverberation time RT (0.4 s, 0.8 s, and 1.2 s), in two noise conditions (background noise at 25 dBA and Babble noise at 61 dBA), in three different auditory feedback levels (-5 dB, 0 dB, and 5 dB), for a total of 18 tasks per subject presented in a random order. The subjects answered questions addressing their perception of vocal fatigue on a visual analog scale. Babble noise and the order of task presentation increased SPL and self-reported fatigue. The SPL increased when the RT and the auditory feedback level decreased further clarifying how vocal effort changes within various conditions.
Using acoustics to examine odontocete foraging ecology: Predator-prey dynamics in the mesopelagic
Authors: Benoit-Bird Kelly J. , Southall Brandon , Moline Mark A.
Published: November 2016

From his expertise in biosonar, Whitlow Au brought a wealth of ideas on sonar use, design, and context to the study of wild cetaceans, resulting in great contributions to our understanding of odontocete foraging ecology. This contribution follows that foundation, using an integrated approach comprising echosounders deployed in a deep-diving autonomous underwater vehicle, ship based acoustics, visual observations, direct prey sampling, and animal-borne tags to explore the behavior of Risso’s dolphins foraging in scattering layers off California. Active acoustic measurements demonstrated that Risso’s dolphins dove to discrete prey layers throughout the day and night. Using acoustic data collected from the AUV, we found layers made up of distinct, small patches of animals of similar size and taxonomy adjacent to contrasting patches. Prey formed particularly tight aggregations when Risso’s dolphins were present. Squid made up over 70% of the patches in which dolphins were found and more than 95% of those at the deepest depths. Squid targeted by dolphins in deep water were also larger, indicating significant benefit from these rare, physically demanding dives. Careful integration of a suite of traditional and novel tools is providing insight into the ecology and dynamics of predator and prey in the mesopelagic.
Echolocation behavior of the Icelandic white-beaked (Lagenorhyncus albirostris) dolphins: Now and then
Authors: Rasmussen Marianne H. , Koblitz Jens , Stilz Peter
Published: November 2016

First studies of the echolocation behaviour of free-ranging white-beaked dolphins (Lagenorhyncus albirostris) were conducted in Faxafloi Bay in the Southwestern part of Iceland in the years 1997 to 1999. However, the sighting rate of white-beaked dolphins has decreased in that area since then and the current studies were conducted in the Northeastern part of Iceland. The aim of this study was to investigate the difference between normal clicks compared to clicks from buzz sequences. The recordings of the Icelandic white-beaked dolphins were conducted using a vertical linear 16-hydrophone array in Skjalfandi Bay, Northeastern Iceland during August 2015 and June 2016. The hydrophones were connected to NI-Boards and to a laptop computer on board using a sample rate of 1 MHz per channel. The group size of the dolphins varied from three individuals up to 30 animals in the area during the recordings. The dolphin echolocation clicks were recorded and it was possible to track individuals and to estimate beam-pattern from their clicks. Estimated beam pattern from 45 regular clicks gave -3dB BW of 9.6 degrees and maximum source level was 208 dB re. 1mPa. In addition buzzes with short inter-click-intervals down to 2.5 ms were recorded on all 16 channels.
From dolphin sonar to commercial scientific acoustic systems
Authors: Andersen Lars N.
Published: November 2016

Dolphins have remarkable sonar systems for underwater navigation, object detection, object inspection, and general understanding of the environment. It is easy to be inspired by these advanced biosonar systems when designing new advanced commercial sonar systems. Similarly, it is also easy to be inspired when discussing bioacoustics with Whitlow Au. His work on dolphin sonar systems has been and still is of significant inspiration for many working with both biological and manmade sonar systems. Personal examples on how Whitlow Au has inspired development of commercial scientific echo sounders will be given. Characteristics of dolphin sonar and commercial scientific acoustic systems will be discussed.
The echolocation beam of bottlenose dolphins (Tursiops truncatus): High-resolution measurements of horizontal beam patterns and nearfield/farfield transitions
Authors: Mulsow Jason , Finneran James J. , Branstetter Brian K. , Moore Patrick W. , Martin Cameron , Houser Dorian S.
Published: November 2016

The work of Whitlow Au and colleagues has demonstrated that dolphin biosonar forms a highly directional, forward-facing beam. In our recent studies, we have expanded upon previous work by making biosonar beam measurements using high-resolution hydrophone arrays with up to 48 hydrophones. Bottlenose dolphins were trained to echolocate on both physical targets and phantom echo generators, with clicks simultaneously recorded on all hydrophones at a sampling rate of 2 MHz. Target ranges (and simulated target ranges for phantom echoes) were varied in order to examine the resulting effects on the spatial characteristics of the acoustic field. The directivity index of the echolocation beam increased with increasing click level and center frequency, and recordings from extreme off-axis azimuths displayed a two-pulse pattern best explained by internal reflections off of the premaxillary bones. High-density hydrophone arrays placed near echolocating dolphins’ heads demonstrated that a transition from the geometric nearfield to the farfield occurs at approximately 0.3 to 0.4 m from the melon. The results were remarkably similar to the earlier findings of Au and colleagues, and provide further information on the spatial characteristics of the acoustic field associated with dolphin biosonar. [Funding from ONR]
Biosonar radiation field on the forehead of a Risso’s dolphin during prey capture
Authors: Lee Wu-Jung , Yu Hsin-Yi , Au Whitlow W. , Smith Adam , Jen I-Fan , Yang Wei-Cheng , Fan Ying-Ching , Nachtigall Paul E. , Chou Lien-Siang
Published: November 2016

On-animal suction cups with embedded hydrophones allow examination of how signals on the forehead of echolocating odontocetes relate to the internal anatomical structure and the transmission beampattern. Risso’s dolphin (Grampus griseus) is an interesting species for this investigation due to the presence of a unique vertical groove in the middle of their forehead. In this study, a linear array of six broadband suction cup hydrophones were attached along the forehead groove of an adult female Risso’s dolphin trained to catch freshly thawed dead squid in front of an eight-element far-field hydrophone array. The animal’s movement was simultaneously observed using an underwater video camera. A total of nine successful prey captures were recorded. During each catch, the animal first emitted regular echolocation clicks, which quickly transitioned into buzzes (clicks with distinctively high repetition rate) until prey capture. The amplitude and relative time of arrival of these signals across all channels were analyzed. For a subset of trials, the relative amplitude distribution across channels vary significantly between regular clicks and buzzes in a manner that may be explained by beampattern changes. These observations were investigated jointly with data from the hydrophone array and interpreted in light of anatomical structure of the melon.
Real-time monitoring of coastal current and throughflow by ocean acoustical tomography with a time reversal responder
Authors: Zheng Hong , Kaneko Arata
Published: November 2016

The conventional Coastal Acoustic Tomography (CAT) system works in a controlled timing of sound transmission from acoustic stations surrounding an observation site. Data received in each station are sent to an integrated data center via communication network and a real-time mapping of current and sound speed is realized. In a new time reversal mirror CAT system (TRM-CAT) proposed, data received at a few land stations by time reversal responders gather all data transferred to the data center. The SNR of received signals is increased and the cost of field experiment is reduced. The TRM-CAT consists of two types of station, land and response stations. The land station is a conventional CAT station that sends coded signals to the response station and receives time reversal signals released. The response station work as a responder, which does not transmit any acoustic signals, until a signals coming from the land station are recorded in a memory, and then reconstructed as a time reversal data to transmit toward the land station at a pre-determined timing. One-way travel time and travel time difference are determined by a matched filter with codes. As a results, the average sound speed and flow velocity can be calculated in land stations. The TRM-CAT is designed and the system simulation is presented. Application to monitoring volume and heat transports through straits and rivers in real time is planned now. Finally, the TRM-CAT serves as a cost effective system for real-time mapping of velocity structures in the coastal sea.
An acoustic tomography method for imaging ocean structure with reverberated waves
Authors: Dunn Robert A.
Published: November 2016

Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean-bottom seismographs is a common technique for exploring earth structure beneath oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. Ignored by the earth scientist, this data offer an alternative approach for determining the structure of the oceans and advancing understanding of ocean heat content and mixing processes. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the traveltimes of reverberated waves to image ocean acoustic structure. To demonstrate the feasibility of applying this method to existing and future data collected as part of marine seismic studies, a synthetic example is devised and the maximum resolution of the method is explored in the presence of different levels of data noise. Reverberation tomography offers significant improvement over classical ocean tomography in that it can produce images of ocean sound speed over the entire vertical height of the water column and along long survey profiles (100 + km), on a scale much finer (100s of meters) than traditional tomography. Variations in acoustic wave speed of <1 m/s are possible to detect with existing technology.
Capabilities and challenges of ocean acoustic tomography in Fram Strait
Authors: Sagen Hanne , Worcester Peter F.
Published: November 2016

The Fram Strait is of great importance in ocean climate monitoring, as it is the only deep-water connection between the Arctic and Atlantic Oceans. Even though an extensive array of oceanographic moorings has been operated in Fram Strait since 1996 to monitor the transports through the Strait, the small spatial scales of the flow are poorly resolved, leading to large uncertainties. Beginning in the 2005-2010 DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies) project, underwater acoustic methods were introduced to improve the monitoring of Fram Strait. A 2008-2009 pilot study with a single acoustic path was followed during 2010-2012 in the ACOBAR (ACoustic technology for OBserving the interior of the ARctic Ocean) project by the implementation of a multipurpose acoustic network with a triangle of acoustic transceivers for ocean acoustic tomography, ambient noise, and glider navigation. The measurements were continued during 2014-2016 in UNDER-ICE (Arctic Ocean Under Melting Ice), with eight acoustic paths crisscrossing the Fram Strait at 78-800N. Tomography in Fram Strait is demanding. The sound-speed field has a weak sound channel with little geometric dispersion, making it difficult to resolve and identify individual arrivals. The strong oceanographic variability in space and time reduces the coherence of the received signal and the stability of the arrival pattern. The status of tomography in Fram Strait will be summarized, focusing on the capabilities and challenges.
Backscatter coefficient estimation in human thyroid carcinoma In vivo
Authors: Rouyer Julien , Laimes Rosa , Salazar Claudia , Pinto Joseph , Guerrero Jorge , Lavarello Roberto
Published: November 2016

Spectral-based quantitative ultrasound (QUS) characterizations may provide a potential alternative to invasive gold standard technique—fine-needle aspiration (FNA)—in the diagnostic management of the thyroid cancer. Such potentiality was previously demonstrated in mouse thyroid cancer models ex vivo. Recently, the feasibility of the backscatter coefficient (BSC) estimation of human thyroid in vivo was demonstrated for a controlled group of 20 healthy volunteers (24.4 ± 2.9 year-old). Among the volunteer, the integrated BSC parameter was found equal to 1.41x10-2sr-1.cm-1 in the 3 to 9 MHz range. The current study focuses on the estimation of the BSC in a clinical context. Preliminary results on patients having malignant lesions are proposed. A research ultrasound imaging system (SonixTouch with an L14-5/38 linear array, Ultrasonix Medical Corp.) was employed by the radiologists of an oncological center first to record radio frequency data of the lesion and second to guide the FNA. The reference phantom technique was used in the same fashion as for the previous healthy volunteer’s study. The experimental protocol was approved by an Institutional Review Board, and all enrolled patients provided written informed consent. A controlled group of seven patients with a diagnosed papillary or follicular carcinomas were included in this pilot study to assess the ability of the technique to estimate the BSC and derived parameters in the lesions.
Elasticity imaging of inhomogeneous media using inverse filtering with multiple shear wave generation
Authors: Shiina Tsuyoshi
Published: November 2016

Most diseases like cancer cause to change of tissue mechanical properties described by elasticity. Elastography visualizes these changes and aids in early and differential diagnosis of diseases. Shear wave imaging is one of principles of elastography, and using the speed of shear wave generated by mechanical vibration or the acoustic radiation force impulse. Conventional shear wave imaging uses time-of-flight method; however, it causes artifact by reflection and refraction of shear wave. We proposed a method for shear wave elasticity imaging that combines inverse filtering with multiple shear wave sources induced by acoustic radiation force. Shear waves are induced by pushing pulse and recorded by ultrafast imaging, and repeated at multiple pushing points that are sparsely located. An inverse filter can be applied to virtually focus shear waves on an arbitrary point. Shear wave speed is obtained by a measured shear wavelength and its image is constructed by scanning the focal point. An inverse filter can focus a point in a reverberant field. Thus, the proposed method is not based on the assumption of propagating direction, and improved estimation accuracy can be expected. The feasibility of the proposed method was demonstrated in phantom experiments.
An evaluation on voice intelligibility for factory noise reduction based on integration of active noise control and auditory masking
Authors: Ito Rumi , Fukumori Takahiro , Nakayama Masato , Nishiura Takanobu
Published: November 2016

Factory noise has been focused upon as one of the social problems. Factory workers exposed to loud, continual noises feel strong discomfort by hearing the loud factory noises for a long time. We have previously proposed an integration method of the active noise control (ANC) and the auditory masking for a noise reduction. The ANC reduces the sound pressure level of the noise in a lower-frequency band by emitting the secondary signals, and the auditory masking reduces discomfort which caused the spectral peaks in a higher-frequency band by emitting the secondary signals. We confirmed that the proposed method is effective for reducing discomfort. However, the method might disturb conversations among the workers by emitting secondary signals. In this study, we therefore evaluated the voice intelligibility of the noise-reduced speech obtained by applying the proposed method to the noisy speech recorded in the factory. As a result of the evaluation experiment, we confirmed that the proposed method can keep voice intelligibility almost the same as the intelligibility of the clean speech in the amid factory noise. In addition, we investigated the relationship between the voice intelligibility and each method under the condition that the controlling frequency-bands are set at to 0–500 Hz for ANC and 500–5500 Hz for auditory masking.
Head-related transfer function personalization based on spectral notch estimation with stereo images of pinna
Authors: Zuo Zhuan , Yoshimura Taku , Fukumori Takahiro , Nakayama Masato , Nishiura Takanobu
Published: November 2016

Three-dimensional (3-D) sound field reproduction systems such as surround sound reproduction systems are rapidly being developed in recent few years. However, these systems need a lot of space for the placement of loudspeakers. For this reason, a binaural system has been studied as one of the systems, which controls the sound image localization with the head-related transfer functions (HRTFs) and just by using only a headphones. However, the individual differences in body features would cause the variations of HRTFs which greatly affect the direction perception. For this reason, a method based on the spectral notch estimation from the pinna shape has been studied for the personalization of HRTFs. In this study, we propose a new method, in which the depth information used for the spectral notch estimation is measured with stereo images of the pinna. Two cameras are utilized together as a stereo camera to take the disparate stereo images so that we can use the disparity of them to measure the depth information of the pinna. As a result of an evaluation experiment, we could reduce the cost of actual measurement and the burden to the subjects by the proposed method.
Relation between area of shielding bone-conduction microphone and quality of speech communication in noisy environment
Authors: Takahashi Kojiro , Muto Kenji , Yagi Kazuo
Published: November 2016

The doctor does not receive the transmitted voice of the patient when the patient becomes unwell in MRI examination, because the voice is faint and MRI acoustical noise is loud. Our purpose is to improve the quality of speech communication of bone-conduction microphone to transmit the patient's faint voice to the doctor. We propose the theoretical formula using the characteristic of vibration propagation for calculating the quality in the case of the shielding microphone. In this report, the improvement level of speech communication quality in the case of the shielding microphone is estimated by the proposed formula in order to discuss the accuracy of the proposed formula. Here, the improvement level of shielding was calculated with a phantom. The phantom consists of a ceramic plate and a silicon rubber representing bones and muscles, respectively. The vibration of vertical direction on the phantom was measured with accelerometers to calculate the improvement level. The results showed that the quality of speech communication is improved by the shielding area, such as an earmuff, to the level of 3 dB.
Metasurfaces for perfect transmission of sound from air into water
Authors: Bok Eun , Choi Haejin , Park Jong J. , Lee Sam H.
Published: November 2016

Three orders of magnitude difference in acoustic impedance between air and water has so far prevented effective sound transmission through the interface. A conventional method for an antireflection coating is a quaterwave plate. Such a coating would be too thick and bulky because acoustic waves in audible range are long. More importantly, one cannot find a suitable coating material among the naturally occurring materials, the acoustic impedance of which is required to be a geometrical mean of those of air and water. Here, we present fabrication of acoustic metasurfaces of thickness much smaller than the wavelength, which allows perfect transmission of sound through the air/water interface. The metasurface is a two dimensional array of unit cells which are consisting of membrane and cavities. Our work demonstrates usage of metamaterials for impedance matching in extreme conditions.
Gain and directivity of exponential horn receivers
Authors: Mennitt Daniel J. , Fristrup Kurt
Published: November 2016

The self-noise of acoustical sensors limits their capacity to monitor extremely quiet environments and measure the subtle, adventitious cues that animals routinely rely upon. Although primarily used in sound production, horns also can amplify sound prior to transduction by a microphone. Given the small size of microelectromechanical microphones, substantial gain can be achieved at wavelengths larger than the horn. An analytical model of an exponential horn embedded in a rigid spherical housing was formulated to describe the gain relative to a free-field receiver as a function of frequency and angle of arrival. Through comparison with experiment and numerical models, the directivity of the horn receiver is shown to be adequately described by the analytical model up to a critical wavelength, beyond which physical assumptions are violated to some degree. Numerical models, based on the equivalent source method, describe the acoustic scattering within and around the horn and provide a means for identifying the mechanisms of deviation in gain at high frequencies and large angles of arrival.
Western and non-western approaches to control timbre using multi-resonator/generator systems of wind instruments
Authors: Braasch Jonas
Published: November 2016

Wind instruments are often modeled as a coupled generator-resonator system, which for the case of the clarinet consists of a reed and a cylindrical pipe. However, the fact that the throat and oral cavities behind the tone generator also play a critical role is often neglected. While the resonance pipe of a wind instrument can be adjusted in length through keyholes or valves, its width is fixed. The opposite can be observed for the human resonance system where the length is fixed but the dimensions of the cross-section are variable. This important fact is routinely used to shape the timbral qualities of tones. In many non-western music cultures, time-varying timbral modifications are more important than melodic aspects, for example, in traditional digeridoo practice. The effects of vocal tract control including Tongue Controlled Embouchure (TCE) will be analyzed and discussed using extended saxophone techniques with adaptive mouthpieces [Braasch, 2014, J. Acoust. Soc. Am. 135, 2245].
Finite-difference model of mode shape changes of the Myanmar pat wain drum circle with tuning paste on drum head
Authors: Bader Rolf
Published: November 2016

The tuning process of drums differ considerably between Western and Southeast Asian drums. While Western drums, like tom-toms, snare, or bass drums of a rock or jazz drum kit, are tuned by changing the tension of the drum head, many drums in Southeast Asia are tuned by adding a paste consisting of rice and ash. As an example, the tuning of the Myanmar pat wain, a unique drum circle of a hsain wain orchestra is investigated. The pat wain has 20 pitched drums and is played with great virtuosity. It was investigated by the author during a field trip in northern Myanmar during its tuning process. The drum head is modeled using a time-dependent Finite-Difference Method (FDM) to estimate pitch and mode changes due to adding the paste. The results are compared to the field recordings which show considerable damping and pitch glides with low-pitched drums. Also the tuning of the drum circle is compared to different tuning systems showing similarities to a tuning pattern of Cambodian roneat deik metalophone.
Field fit testing with E-A-Rfit Dual-Ear validation system in China
Authors: Liu Yufei , Gong Wei , Yang Min
Published: November 2016

This presentation introduces hearing protection fit testing on over 1000 workers in 6 different factories, each with different hearing conservation practices in China. The 3MTM E-A-RfitTM Dual-Ear validation system was used to measure the Personal Attenuation Rating (PAR), on three different types of Hearing Protection Devices (HPDs), including a foam earplug, a premolded earplug, and a headband earmuff at the work site. A follow up visit to repeat fit-testing was conducted approximately 6 months after the initial visit. Field attenuation of HPDs obtained by workers’ and the effects of training toward improving the attenuation were observed. In addition, PARs for the Peltor™X4A earmuff users were obtained at several points throughout the work shift to capture different fits. Result shows that there is wide variability in PARs and poor agreement between PAR and labelled noise attenuation ratings obtained from laboratory measurement. Hearing protection fit testing is essential to verify the sufficiency of attenuation. Training together with fit testing was shown to improve the PAR. Key words: Hearing Protection Device (HPD), fit testing, Personal Attenuation Rating (PAR), China.
Personal attenuation ratings reported using Fit Check Solo™: Is background noise a concern?
Authors: Murata Taichi K. , Gallagher Hilary , McKenna Elizabeth A. , Wolff Gregory G. , Sullivan Sarah C. , Ankrom Matthew R. , Murphy William J. , Abouzahra Nourhan K. , Hecht Quintin A.
Published: November 2016

It is well known that some personnel, especially Service Members, operate in hazardous noise-environments. To reduce the risk of hearing loss and hearing related disabilities, hearing protection devices (HPDs) are worn to decrease the level of noise at the ear. Noise attenuation provided by HPDs can vary greatly depending on user fit. Fit test systems were developed to measure the noise attenuation performance of HPDs and to report a personal attenuation rating (PAR) based on that particular fit. Elevated levels of background noise in a typical office-type setting (in comparison to a laboratory) could however affect PAR results. A study completed by the Air Force Research Laboratory compared PAR results of 3M EAR Classic earplugs and Howard Leight Airsoft earplugs from data collected using ANSI S12.6 methodology in the laboratory and data collected using Fit-Check Solo™ in an office environment, a controlled noise office environment, and the laboratory. Results demonstrated that PARs were affected by increased background noise; however, the significance varied based on the number of frequencies used in the PAR calculation. Experimental methodologies, PAR results, and background noise levels will be presented.
Uncertainty of hearing protector impulsive attenuation measurements
Authors: Fackler Cameron J. , Berger Elliott H. , Stergar Michael E.
Published: November 2016

Measurement of the impulsive protection of a hearing protection device (HPD) is currently standardized in ANSI/ASA S12.42-2010 as a measurement of impulse peak insertion loss (IPIL). IPIL is a time-domain metric, determined as the difference between open-ear and occluded-ear peak sound pressure levels of an impulse, measured without and with an HPD in place on an acoustic test fixture. To characterize potential level-dependent protection of an HPD, the IPIL test is repeated at several free-field impulse peak sound pressure levels, typically ranging from approximately 130-170 dB. Based on our experiences measuring IPIL with both a shock tube and a rifle serving as the impulse source, as well as a review of existing literature reporting IPIL studies, we discuss and attempt to quantify the uncertainty of such measurements. Sources of uncertainty include the repeatability of the impulse source, characteristics of the sound field created by the impulse source, spectral characteristics of both the impulse source and the HPD’s attenuation, variability between HPD samples and repeat fitting of the HPD to the acoustic test fixture, and variability in the measurement instrumentation and data analysis procedures. Our estimates will be compared to those provided in the uncertainty annex of S12.42.
Middle ear muscle contractions from non-acoustic elicitors
Authors: Flamme Gregory A. , Tasko Stephen M. , Deiters Kristy K. , Ahroon William A. , Murphy William J.
Published: November 2016

High-level sounds can elicit middle ear muscle contractions (MEMC), which are commonly known as acoustic reflexes. Tactile stimulation to the face can also elicit MEMC, and it is plausible that MEMC could co-occur with voluntary eye closure gestures. In this paper, we shall present preliminary MEMC results from human volunteers receiving controlled tactile stimulation (nitrogen gas, 10 kPa, 200 ms duration) to four locations on the face and who close the eye ipsilateral to the MEMC detection probe. The MEMC were detected via changes in total energy reflected in the ear using a filtered (0.2 to 8 kHz) click train. Concomitant muscle activity was measured using electromyography. The morphology and magnitude of the MEMC from these non-acoustic stimuli will be described. If non-acoustic MEMC behaviors do not extinguish and are not highly susceptible to fatigue, they could represent an opportunity to mediate exposure to short-duration noises or help explain between-person differences in noise exposure outcomes.
Introduction of a hearing conservation program in a Japanese enterprise
Authors: Sasaki Naoko , Ogasawara Takayuki , Denda Ikuo , Inoue Jinro , Horie Seichi
Published: November 2016

To prevent occupational hearing loss, the Ordinance of Industrial Safety and Health in Japan requires employers to measure sound levels in eight hazardous areas in the workplace. In addition, the Guidelines for the Prevention of Noise-Induced Impairments require employers to measure the sound levels in noisy workplaces or provide audiometric testing for employees exposed to occupational noise. However, measurement of personal noise exposure is not a legal requirement in Japan. The Japanese Working Environment Measurement Standards define how to measure occupational noise using a sound level meter (SLM). However, it is difficult to evaluate real noise exposure for employees who use a sound-emitting industrial tool. We measured this exposure using a dosimeter at a Japanese manufacturing enterprise producing transport machinery. The sound levels at some workshops that were evaluated as 85 dBA using a SLM were shown to be more than 90 dBA using a dosimeter. Following these results, we are introducing a Hearing Conservation Program at the enterprise. We would like to report how to develop this new noise management system in Japan and manage personal noise exposure.
Acoustomicrofluidics for micro-object Manipulation
Authors: Destgeer Ghulam , Sung Hyung Jin
Published: November 2016

Interaction of acoustic waves with fluids at a microscale have shown great potential in realizing efficient actuation of liquids for atomization/nebulization, mixing, pumping, gradient generation, etc. It has also enabled researchers working in various fields to dexterously manipulate suspended micro-objects—microparticles, cells, microorganisms—for concentration, separation, sorting, medium exchange, etc. Surface acoustic waves (SAWs)—travelling as well as standing—have been used to demonstrate several of the above mentioned applications with great success. In particular, standing SAWs along with other bulk acoustic waves-based techniques have been proven to efficiently and continuously separate micro-objects inside a microfluidic channel. Our focus has so far been to explore the unexplored use of travelling SAWs to unravel some of the associated advantages. We have used high frequency travelling SAWs—O(100 MHz)—to separate microparticles flowing through a microchannel or suspended within a sessile droplet. Contrary to the formation of pressure nodes in standing SAWs for micro-object manipulation, traveling SAWs generate a strong acoustic streaming flow and impart a direct acoustic radiation force on the suspended particles for efficient manipulation capabilities with all the additional advantages of their non-invasive nature, label-free manipulation, biocompatibility, low costs, and simplicity in operation.
Pattern deposition on an ultrasonic actuator
Authors: Manor Ofer
Published: November 2016

In recent years, one has observed an increasing interest in the pattern deposition of colloidal particles from an evaporating carrier liquid, a process associated with the coffee ring effect. In particular, various companies employ pattern deposition for the fabrication of medium resolution conducting circuits for various applications from touch screens to antennae. In this talk, I will discuss the pattern deposition of solute particles off an evaporating solution film atop an ultrasonic actuator. We use the actuator to generate a MHz vibration in the form of a Rayleigh surface acoustic wave (SAW), propagating in the solid substrate and under the solution film at a phase velocity of 4000 m/s. Transfer of momentum from the SAW to the neighboring solution translates to an acoustic stress, supporting various flow mechanisms, i.e., acoustic streaming, and altering the geometry of the evaporating film. The interplay between the capillary, acoustic, and evaporative stresses within the solution determines the transport dynamics of the solute particles in the solution and the state of pattern deposition on the solid substrate. Using different SAW power levels we alter the dynamic state of the deposition, changing the qualitative geometry of the deposited patterns from dots to stripes and from stripes to solid films.
Isolating cochlear synaptopathy in people with impaired audiograms: An auditory brainstem and envelope-following response modeling study
Authors: Verhulst Sarah , Vasilkov Viacheslav , Jagadeesh Anoop , Pelz Markus
Published: November 2016

Listeners with impaired audiograms likely suffer from mixtures of peripheral hearing pathologies that include outer-hair-cell loss and the more recently discovered cochlear synaptopathy. These mixed pathologies pose challenges for current audiological practice as objective brainstem EEG metrics might not be able to isolate these different hearing deficits. By simulating different degrees of outer-hair-cell and auditory-nerve fiber loss in a functional model of the human auditory periphery, we studied which auditory brainstem (ABR) and envelope-following response (EFR) measures and stimuli are most sensitive to either type of hearing deficit. We validated our model predictions using recordings from 32 listeners with normal or elevated hearing thresholds. The simulations show that high-frequency outer-hair-cell loss steepens the ABR wave-V latency-vs-intensity curve as well as the wave-V amplitude-vs-intensity curve, such that grouping listeners according to the ratio of these metrics (i.e., the ABR growth ratio) offers a way to factor out the outer-hair-cell aspect of hearing loss. Individual differences within an ABR growth ratio group are sensitive to other aspects of peripheral hearing loss such as cochlear synaptopathy. We furthermore simulated EFRs to pure-tone and broadband stimuli of different modulation depths to study which EFR metrics are sensitive to synaptopathy in hearing impaired listeners.
No evidence for hidden hearing loss due to noise exposure in young adults with a normal audiogram
Authors: Kluk Karolina , Prendergast Garreth , Guest Hannah , Munro Kevin J. , Léger Agnès , Hall Deborah A. , Heinz Michael , Plack Christopher J.
Published: November 2016

Cochlear synaptopathy, or “hidden hearing loss,” refers to a loss of synapses between inner hair cells and auditory nerve fibers, and affects primarily low-spontaneous-rate fibers that encode moderate-to-high intensity sounds. In rodent models, cochlear synaptopathy has been shown to occur as a result of noise exposure even when threshold sensitivity is unaffected. We tested 126 young humans with normal audiograms and a wide range of lifetime noise exposures quantified using a questionnaire. Our electrophysiological and behavioral measures were designed to be sensitive to the contribution of low-spontaneous-rate fibers. We predicted that our test battery would reveal that noise exposure is associated with attenuated electrophysiological responses, and elevated behavioural thresholds, especially at higher levels and frequencies. However, there was no relation between noise exposure history and auditory brainstem response wave I amplitude, nor performance on psychophysical tasks including modulation detection, inter-aural phase difference discrimination, frequency discrimination, and intensity discrimination. There was also no relation between noise exposure and speech-in-noise performance nor self-report listening ability. Only the 16 kHz audiometric thresholds were correlated positively with noise exposure for females, but not for males. Our results suggest that cochlear synaptopathy due to noise exposure is not easily identifiable in young humans with a normal audiogram. [This work was supported by the MRC UK (MR/L003589/1).]
Auditory brainstem responses to anechoic and reverberant two-syllable speech sounds in elderly listeners
Authors: Fujihira Haruna , Shiraishi Kimio , Remijn Gerard B.
Published: November 2016

Elderly listeners often complain of difficulty in understanding speech under reverberation. To investigate speech processing in elderly listeners’ auditory pathways, some studies have focused on auditory brainstem responses to speech sounds (speech ABRs). In an earlier study, we measured speech ABRs to the speech sound /da/ in elderly listeners and reported that listeners with low word intelligibility under reverberation showed small amplitudes in their speech ABRs to a formants frequency of/da/ (Fujihira & Shiraishi, 2015). Reverberation is a phenomenon that causes speech sounds to overlap with following speech sounds. Therefore, the effects of reverberation on multiple syllables might be larger than those on one syllable. In present study, we measured the speech ABRs to the two-syllable sound /dada/ in 27 elderly listeners and investigated the difference between the speech ABRs to the first syllable and the second syllable in anechoic and reverberant conditions. The results showed that the amplitudes of speech ABRs to the first syllable decreased compared to those to the second syllable in the anechoic condition, but both amplitudes to the first syllable and the second syllable in the reverberant condition decreased almost equally.
Interaural spectral mismatch and binaural fusion in simulated cochlear-implant listening for single sided deafness
Authors: Wess Jessica M. , Spencer Nathan J. , Bernstein Joshua G.
Published: November 2016

Cochlear implants (CIs) can restore some spatial-hearing capabilities for individuals with single-sided deafness (SSD). However, there is a considerable variability in outcomes among SSD-CI listeners. One possible cause is spectral mismatch between the acoustic and CI ears. Vocoder simulations of SSD-CI listening were used to investigate the effect of interaural spectral mismatch on subjective fusion for normal-hearing listeners. A virtual cocktail party was created by presenting combinations of 1-6 concurrent talkers to the left, right or both ears. After each trial, listeners were asked how many total voices were heard. If listeners were able to perceptually fuse the voices that were presented to both ears, they should be more likely to report the correct number of total talkers in the scene. If not, they should report more total talkers. Preliminary results show that listeners reported more total talkers when the vocoded speech was processed with a frequency-matched map (simulating a standard CI frequency allocation) then with a place-matched map. These data suggest that place-matched CI mapping has the potential to provide SSD-CI listeners with more opportunities for binaural fusion and improved spatial hearing. This method could be applied to SSD-CI listeners to evaluate mapping strategies and outcomes after implantation. [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.]
Acoustic scattering from finite bilaminar composite cylindrical shells with doubly periodic stiffeners—3-D solution
Authors: Hayek Sabih I. , Boisvert Jeffrey E.
Published: November 2016

The acoustic scattering from an insonified finite bilaminar cylindrical shell is analyzed. The shell is reinforced by a two sets of rib-stiffeners to form a doubly periodic stiffened shell. The two cylindrical shell laminates are perfectly bonded having the same lateral dimension but have different radii and material properties The two sets of rib-stiffeners have rectangular cross-sections and are perfectly bonded to the inside of the inner shell. One set of stiffeners is heavy and the other set is light, so that a finite number of light stiffeners are set within every pair of heavy stiffeners. The bilaminar stiffened shell is analyzed using the exact theory of three-dimensional elasticity. The stiffeners are analyzed as elastic rings with extensional, torsional, and in-plane and out-of-plane flexural rigidities. The scattered acoustic farfield is evaluated for various incident plane wave frequencies. Shells with different combinations of light to heavy stiffener geometries are analyzed. A uniform steel stiffened shell submerged in water and stiffened with doubly periodic stiffeners was initially analyzed. A second shell made up of an outer elastomer shell bonded to an inner stiffened steel shell was also analyzed. [Work supported by NAVSEA Division Newport under ONR Summer Faculty Program.]