bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian model averaging of infrasound propagation models
Authors: Millet Christophe , Bertin Michaël
Published: November 2016

In infrasound propagation modeling, we often face a large number of potential models with only a limited number of recorded signals to conduct inference from. Prediction of acoustic signals is a complex issue due to constantly changing atmospheric conditions and to the random nature of small-scale flows (turbulence, gravity waves). Thus, the uncertainty over which model to use (both for atmospheric specifications and acoustic propagation) is an important aspect of forecasting and indeed any inference from data. In standard practice data analysts typically select a model from some class of models (linear propagation models, ray tracing techniques,...) and then proceed as if the selected model had generated the recorded signal. Such an approach ignores the uncertainty in propagation model selection, leading to over-estimated confidence intervals. In the present work, we use Bayesian Model Averaging (BMA) as a basis for inference about parameters of interest. This approach offers a systematic method for checking the robustness of one’s results to alternative model specifications. The method's performance is demonstrated using several data sets from the International Monitoring System (IMS). Our results demonstrate that a Bayesian probabilistic approach together with methods of model reduction to infrasound propagation can improve significantly the posterior distributions from the continuous stream of automatic detections of IMS infrasound stations.
Strong fluid-structure coupling in a two-dimensional waveguide bounded by elastic plates
Authors: Ginsberg Jerry H.
Published: November 2016

The typical model for compliant walls in a waveguide take them to be locally reacting. The corresponding boundary conditions for the transverse mode functions are Robin-type, which leads to an analysis that is a straightforward modification of the conventional analyses for rigid and pressure-release walls. The present investigation takes up the case where the walls are elastic plates, and the fluid loading is heavy. The consequence is strong coupling of the fluid and structural responses. The fact that the walls are not rigid obviates the possibility of a planar mode, so it is necessary to consider the transverse dependence of modes at any frequency. The analytically derived characteristic equation for the coupled response vividly displays the interaction of elastodynamics and acoustics. The eigenvalues are the transverse wavenumbers of the various modes at a specified frequency. They can be obtained through numerical methods, but implementing such a procedure to obtain dispersion curves of transverse wavenumber vs. frequency for each mode is cumbersome. An alternative procedure based on contours of the characteristic equation is exceptionally easy to implement, and extensible to other problems. One of the results that follow from the analysis is the observation that there is a minimum frequency below which all modes evanesce.
Vibro-acoustics of cylindrical shells with distributed damping liners
Authors: Singh Rajendra
Published: November 2016

Distributed passive damping treatments (such as cardboard liners, and foam or visco-elastic materials) are routinely placed inside the automotive drive shafts to reduce the airborne and structureborne noise over the applicable mid-frequency range. To better understand the underlying mechanism(s), experimental and analytical studies are undertaken. First, a laboratory experiment is designed to measure vibro-acoustic response functions of a thin cylindrical shell with different cardboard liner thicknesses. Second, the properties of a cardboard liner material are determined by conducting an experiment on an elastic plate treated with a cardboard liner. Third, an analytical framework for shell vibration is developed and the relative sliding motion between substructure and liner is explicitly described. The proposed model agrees well with the experiment in terms of natural frequency shifts, modal loss factors, and modal insertion losses. Several damping mechanisms such as material damping, dry friction, and interfacial viscous friction are examined. Finally, various aspects of the problem including unresolved issues will be briefly discussed.
Axial force measurement for U-bolt using wave propagation speed monitoring
Authors: Toh Gyungmin , Min Dongki , Lee Jaehong , Park Junhong
Published: November 2016

It is important to inspect clamped parts of a produced vehicle in the manufacturing process non-destructively. In this study, a measuring device of axial force is suggested by utilizing relations between wave propagation characteristics of a beam and a clamping force. Experiments were carried out to determine characteristics of vibration signals for the structure designed for inspection. Neodymium magnet was utilized as the components of the device to attach to the joint without any damage to the products. A rectangular parallelepiped magnet was used to detect the change in the wave propagation speeds in the structure. The change in the wave propagation through the bolt was measured and used in estimation of the axial force. The correlation coefficient was calculated to quantify the change in the wave propagation characteristics. The coefficient was utilized to determine the axial force of the bolted joint by the experiment. The proposed method was applied to actual U-bolts to validate the methodology.
Passive defect detection in plate from nonlinear conversion of low-frequency vibrational noise
Authors: Moulin Emmanuel , Chehami Lynda , Assaad Jamal , de Rosny Julien , Prada Claire , Chatelet Eric , Lacerra Giovanna , Gryllias Konstantinos , Massi Francesco
Published: November 2016

It is known that, under the assumption of diffuse noise, the cross-correlation of acoustic signals recorded at two points of a medium allows to passively estimate the impulse response between these points. This principle, associated with coherent array processing, has been successfully applied to defect detection and localization in reverberant plates subject either to distributed noise sources or friction noise. In order to extend the applicability of this principle even in the absence of an adequate ambient noise, we have introduced the concept of secondary noise sources based on the conversion of low-frequency modal vibrations into high-frequency noise by exploiting frictional contact nonlinearities. The device consists of a mass-spring resonator coupled to a flexible beam by a rough frictional interface. The extremity of the beam, attached to the surface of a plate, excites efficiently flexural waves in the plate in the ultrasound range when the primary resonator vibrates around its natural frequency. We have shown that a set of such devices distributed on a plate excited by a shaker at low frequencies is able to produce high-frequency noise suitable for passive defect detection and localization based on noise correlation.
A physical figure model of lips for speech production
Authors: Hirayama Makoto J.
Published: November 2016

A physical figure model of lips were made. In previous studies, tongue models consisting of intrinsic and extrinsic tongue muscles were made using viscoelastic material of urethane rubber gel. At this time, as other important speech articulators, upper and lower lips are modeled using urethane rubber gel. Also, a movable jaw model is made from plastic cray. The lips model is placed on the jaw model. As the lips model is made from viscoelastic material similar to human skin, reshaping and moving lips are possible by pulling or moving lips and jaw by hand to emulate speech articulation of lips and jaw. Orofacial muscles such as orbicularis oris, levator labii superioris, levator anguli oris, depressor anguli oris, depressor labii inferioris, and mentalis are considered for lip motions with the figure model. The proposed model is useful for speech science education or a future speaking robot development based on realistic speech production mechanisms.
Learning from visual speech
Authors: Taylor Sarah , Kim Taehwan , Yue Yisong , Milner Ben , Matthews Iain
Published: November 2016

Realistic animation of faces has proven to be challenging due to our sensitivity in perceiving visual articulation errors. We study the problem of learning to automatically generate natural speech-related facial motion from audio speech which can be used to drive both CG and robotic talking heads with low bandwidth requirements and low latency. A many-to-one mapping from acoustic phones to lip shapes (i.e., static “visemes”) is a poor approximation to the complex, context-dependent relationship visual speech truly has with acoustic speech production. We introduced “dynamic visemes” as data-derived visual-only speech units associated with distributions of phone strings and demonstrated they capture context and co-articulation. Further improvement in predicting visual speech can be achieved using an end-to-end deep learning approach. We train a sliding window deep neural network that learns a mapping from a window of phone labels or acoustic features to a window of visual features. This approach removes the requirement for visual units and can very accurately predict visual speech from phone labels or the audio signal directly. We demonstrate the effectiveness of these approaches on CG face models and discuss their application to animatronic heads.
A robot-based enjoyable conversation system
Authors: Kobayashi Tetsunori
Published: November 2016

A robot-based enjoyable conversation system, SCHEMA, is introduced. The first main function of this robot is acting as a facilitator who keeps the balance of engagement density in a group conversation. In a group conversation, sometimes only a particular pair of participants talk each other, and the other particular side participants lose the opportunities to join in the conversation. In terms of total balance of enjoyment of the conversation, this kind of engagement-density-imbalance should be corrected. The proposed robot can find the participants who feel difficulty in joining in a conversation, and give him a chance to join in without destroying existing conversation. The second characteristic function of this robot is generating subjective opinion. In terms of functionality of conversations, it is enough to reply directly to the question that was explicitly asked. However, in our daily conversations, more informative responses are usually employed in order to hold enjoyable conversations. These responses are usually produced as forms of one’s additional opinions, which usually contain their original viewpoints as well as novel means of expression, rather than simple and common responses. The proposed robot can select some messages from WEB review site, arrange them, and generate a message as if it is the opinion of one’s own. In this talk, we show these functions successfully utilized to achieve enjoyable conversation.
Huge microphone array to maximize mutual information between many microphones and sound sources
Authors: Niwa Kenta
Published: November 2016

Hardware technological evolution makes it possible to capture over 100 signals and apply complex processing for, e.g., source enhancement in real time. Assuming that many microphones are available and we want to emphasize a desired sound source located at a distance in noisy environments, how do we place them? In this talk, the principle of spatial sampling to maximize the mutual information between multiple inputs (microphones) and multiple outputs (sound sources) is discussed. The mutual information is commonly used for measuring how much information related to the sound sources is included in many observed signals. In our previous work, we found that it is possible to increase the mutual information by surrounding the microphones with reflectors. Since the effective spatial cues for identifying a desired sound source are included in observed signals, accurate source enhancement would be achieved by applying appropriate mapping functions. Beamforming with/without post-Wiener filtering is used as an implantation of a mapping function. Experiments for emphasizing a desired sound source located 16.5 meters from the constructed microphone array were conducted. Pinpoint pick up of the desired sound source was achieved.
Perceptual thresholds of spatial audio update latency in virtual auditory and audiovisual environments
Authors: Sankaran Narayan , Hillis James , Zannoli Marina , Mehra Ravish
Published: November 2016

When observers in a virtual sound environment are in motion relative to a source, the virtual-auditory display must rapidly track the users head position and update the location-cueing acoustic filters—known as head-related transfer functions (HRTFs)—in order to accurately reflect the source’s location relative to the current head orientation and position. The end-to-end spatial audio system latency (SASL) is the time elapsed between the listener assuming a position and sound being delivered to the ears with an HRTF corresponding to that same position. To maintain the stability and plausibility of a virtual sound “object,” the SASL must lie below a perceptual temporal threshold. The current study sought to rigorously probe the threshold of SASL detectability in human observers at three different rotational head velocities and at various source locations. These conditions were repeated in an audiovisual experiment in which the sound stimulus was now accompanied by a zero-latency visual stimulus. Thus, we characterized SASL thresholds in environments where cross-modal interactions occur due to visual information accompanying sound as is often the case in virtual reality (VR) applications. Initial results reveal a rich interaction between the contextual factors of the virtual environment and listeners’ sensitivity to SASL.
Taking advantage of spontaneous speech for document retrieval: Lessons from the organization of evaluation tasks
Authors: Akiba Tomoyosi
Published: November 2016

This work reports our experiments on organizing evaluation tasks aiming at spoken document retrieval (SDR). The NTCIR Project is a series of evaluation workshops designed to enhance research in information access technologies by providing reusable test collections and a forum for researchers. The author's group has proposed the evaluation tasks for SDR at the NTCIR from 2010. They resulted in holding the four successive evaluation tasks called SpokenDoc-1 and 2, and SpokenQuery&Doc-1 and 2. In the SpokenDoc tasks conducted from 2010 to 2013, we designed and evaluated the SDR tasks targeting spontaneously spoken speech. Based on this data collection, we conducted two subtasks: the spoken term detection subtask and the spoken content retrieval subtask. After two rounds of them, we enhanced our research focus with the query part of information retrieval. In the SpokenQuery&Doc tasks conducted from 2013 to 2016, we investigated the information retrieval systems that take advantage of a spontaneously spoken query as a medium of expressing one's information need. We have collected spontaneously spoken queries through subjective experiment to construct search topics for information retrieval. All of those experiences has been compiled into the reusable test collections provided at the NTCIR project, which enables researchers to test their ideas anytime on the common testbeds. In this presentation, we will report our task design, methodologies and challenges on constructing our data, and outcomes found through our organization.
Prof-Life-Log: Monitoring and assessment of human speech and acoustics using daily naturalistic audio streams
Authors: Hansen John H. L. , Sangwan Abhijeet , Ziaei Ali , Dubey Harishchandra , Kaushik Lakshmish , Yu Chengzhu
Published: November 2016

Speech technology advancements have progressed significantly in the last decade, yet major research challenges continue to impact effective advancements for diarization in naturalistic environments. Traditional diarization efforts have focused on single audio streams based on telephone communications, broadcast news, and/or scripted speeches or lectures. Limited effort has focused on extended naturalistic data. Here, algorithm advancements are established for an extensive daily audio corpus called Prof-Life-Log, consisting of + 80days of 8-16 hr recordings from an individual’s daily life. Advancements include the formulation of (i) an improved threshold-optimized multiple feature speech activity detector (TO-Combo-SAD), (ii) advanced primary vs. secondary speaker detection, (iii) advanced word-count system using part-of-speech tagging and bag-of-words construction, (iv) environmental “sniffing” advancements to identify location based on properties of the acoustic space, and (v) diarization interaction analysis which highlights the amount of speech each individual produces along with recipient direction. The diarization advancements are evaluated on CRSS-UTDallas Prof-Life-Log. Results show improvements in speech activity detection, word count estimation, and environmental sniffing for naturalistic audio streams. The advancements suggest improved speech/language processing algorithms can address the increased diversity in daily audio for speaker knowledge detection/estimation and summarization.
A speech pre-processing method to reduce overlap masking in reverberant environments
Authors: Grosse Julian , van de Par Steven
Published: November 2016

In daily life, we are often exposed to speech that is rendered over loudspeakers in a reverberant acoustical environment (examples are public-address systems used in a train station or conference halls). Whereas the early reflections can support speech intelligibility, the late reflections smear the speech in time which will result in an overlap of consecutive speech portions and an effective low-pass filtering of the speech-specific modulation spectrum. This study proposes a perceptually motivated pre-processing approach, based on previous work of Hodoshima et al. [J. Acoust. Soc. 119, 4055-4064 (2006)], which reduces the detrimental effects of reverberation by suppressing steady-state portions and emphasizing potentially inaudible/masked segments of speech before it is emitted in the reverberant environment. For pre-processing, the impulse response is separated into a direct and a reverberant path to decide whether speech segments are inaudible and can be neglected or should be emphasized. A speech intelligibility prediction model is used to select the optimal pre-processing parameters for each specific acoustical environment. Listening tests showed, that this pre-processing approach is able to partially compensate the detrimental effects of reverberation leading to a reduction in speech reception thresholds of about 2 to 5 dB measured in speech shaped noise.
Shallow-water acoustic variability experiment 2015 (SAVEX15) in the northern East China Sea
Authors: Song Hee-Chun , Kim Sea-Moon , Kim Byoung-Nam , Nam SungHyun
Published: November 2016

The SAVEX15 experiment was conducted in shallow water (~100 m deep) in the Northern East China Sea (ECS), ~100 km southwest of Jeju Island, South Korea, over the period 14-28 May 2015. The goal of SAVEX15 was to obtain acoustic and environmental data appropriate for studying the coupling of oceanography, acoustics, and underwater communications in the ECS. Surprisingly, an underwater sound channel (USC) typical in deep water was discovered in this shallow water waveguide with the channel axis at ~40 m, apparently due to the cross-frontal interleaving of water masses carried by the Kuroshio Current and Changjiang river discharge. This talk presents an overview of SAVEX15 including preliminary research results.
Acoustic propagation in the South China Sea: Internal waves and sand dunes
Authors: Reeder D. Benjamin , Chang Andrea Y. , Chen Chi-Fang , Chiu Ching-Sang , Chiu Linus Y. , Miller Chris W. , Ramp Steven R. , Wei Ruey C. , Yang Yiing J.
Published: November 2016

Very large subaqueous sand dunes were discovered on the upper continental slope of the northeastern South China Sea (SCS) in the spring of 2007 during the ONR 322OA-funded NLIWI Acoustics field experiment. The dunes’ formation mechanism is hypothesized to be the internal solitary waves (ISW) which generate from tidal forcing on the Luzon Ridge on the east side of the SCS, propagate west across the deep basin with amplitudes regularly exceeding 125 m, and dissipate large amounts of energy via turbulent interaction with the continental slope, suspending and redistributing the bottom sediment. These internal waves and sand dunes are important acoustical features, as it is expected that they will cause significant anomalies in the acoustical field. Data analysis and modeling are presented to quantify the degree to which these features impact broadband (850-1200 Hz) signals propagating along an acoustic transect oriented perpendicular to the internal wave fronts and sand dune crests.
Influence of internal wave on the space-time interference patterns of broadband acoustic field
Authors: Hu Tao , Guo Shengming , Ma Li , Song Wenhua
Published: November 2016

The frequency shift of the acoustic interference striations is caused by the depth variation of the thermocline in shallow water waveguide. Based on the perturbation theory, a relationship between the frequency shift of the interference striations and the contoured sound speed profile is established. In a given frequency band, if the modal horizontal wave number difference acts as a monotonic function of frequency, the frequency shift of interference striations has a direct correlation with the contoured SSP. This relationship is verified by simulation calculation as well as experiment data. It is found that if the propagation direction of sound is parallel to the wave front of internal wave, the frequency shift of the interference striations has a determined relationship with the contoured SSP that passing through the source; while when sound propagates in a direction perpendicular to the internal wave’s wave front, the frequency shift is then associated with the contoured mean SSP in the entire sound propagation path.
Melody in my head, melody in my genes? Acoustic similarity, individuality, and genetic relatedness in the indris of Eastern Madagascar
Authors: Gamba Marco , Torti Valeria , Bonadonna Giovanna , Randrianarison Rose M. , Friard Olivier , Giacoma Cristina
Published: November 2016

Indris (Indri indri) are the only singing lemurs and produce different types of songs that can be differentiated according to their temporal patterns. The most distinctive portions of the songs are “descending phrases” consisting of 2-5 units. In our study, indri songs were recorded in the Eastern rainforests of Madagascar from 2005 to 2015. All the recordings were made when the recorder operator was in visual contact with the singing social group and by recognizing individual indris using natural markings. Because the individual songs frequently overlap during the chorus, we extracted the pitch contour of 1084 descending phrases using the program Praat. We tested whether the structure of the phrases could provide conspecifics with information about sex and individual identity. We also examined whether the structure of the phrases was related to the genetic relatedness of the indris. The results suggest that the songs have consistent sex-, group-, and individual-specific features. We have also found a significant correlation between the genetic distance and the acoustic similarity. The descending phrases may be used by the indris to convey information of sex and identity, and genetic relatedness may play a role in determining song similarity to a larger extent than previously assumed.
Recent bioacoustics researches on biosonar, hearing, and noise effect on the Indo-Pacific humpback dolphins (Sousa chinensis)
Authors: Li Songhai , Wang Ding
Published: November 2016

The Indo-Pacific humpback dolphins (Sousa chinensis) are widely distributed in the coastal waters of the tropical and sub-tropical ocean in Asia, including southeast China. Conservation of the humpback dolphins in Chinese waters has been on the agenda of local scientific and conservation communities since the 1980s, despite little research including bioacoustics research has been conducted. Our recent bioacoustics studies indicated that the biosonar clicks of the wild humpback dolphins were short-duration, broadband, ultrasonic pulses, similar to those produced by other whistling dolphins of similar body size. However, their click source levels with an average of around 190 dB re: 1μ Pa in peak-to-peak, appear to be much lower than those of other whistling dolphins. Hearing sensitive frequency range of the humpback dolphins is generally higher than 5 kHz and lower than 120 kHz with possible age-related hearing loss for old dolphins. The humpback dolphin could therefore be characterized as a mid-frequency cetacean, which operates sounds in mid- to high-frequency range. Any sufficiently intense sounds with mid- to high-frequency components could have deleterious effects on the humpback dolphins through interference on animals’ behavior and with the animals’ ability to detect signals from conspecifics, and echoes of echolocation clicks.
A new baleen whale call recorded in the Mariana Trench Marine National Monument
Authors: Nieukirk Sharon L. , Fregosi Selene , Mellinger David K. , Klinck Holger
Published: November 2016

In fall 2014 and spring 2015, passive acoustic data were collected via autonomous gliders east of Guam in an area that included the Mariana Trench Marine National Monument. A short (2-4 s), complex, unknown sound was recorded. The call began with a brief 0.4 s long tone centered at 60 Hz, followed by a 2 s low-frequency moan that sweep from 44—30Hz. The moan appeared to have both amplitude modulation and strong harmonics. The moan was followed by two ~60-150 Hz upsweeps lasting 0.5s that often had diffuse energy up to 1000 Hz. The call ended with metallic-sounding upsweeps with most energy between 700 and 800 Hz, but up to 7.5 kHz. These sounds were recorded regularly during both fall (326 calls during 38 glider dives) and spring (110 calls during 16 glider dives). Many components were not visible in low signal to noise ratio calls. Calls were typically 5-6 minutes apart and often occurred in long sequences. Aurally, the sound is quite unusual and most resembles the minke whale “Star Wars” call. We propose this sound is biological and is likely produced by a baleen whale.
Passive acoustic monitoring of Pygmy blue whales (Balaenoptera musculus brevicauda) in Southern Sri Lanka
Authors: Pekkarinen Annukka , Olive Yeelen , Rasmussen Marianne H.
Published: November 2016

Two ecological acoustic recorders were deployed in Southern Sri Lanka to study the presence of the assumed resident population of pygmy blue whales. A major shipping lane runs through this feeding area of the whales and it has been recognized by the International Whaling Commission as well as International Maritime Organization as a risk area for ship strikes. To implement any management practices to mitigate ship strikes, a solid scientific basis is needed. Such data must include information on migration and movement patterns of the whale population. Therefore, combining the passive acoustic monitoring data with existing visual transect survey results gives further insight to choosing suitable management practices to address the issue. Passive acoustic monitoring data indicate that at least part of the population is indeed resident in the area throughout the year but there is both seasonal and inter-annual variation in the acoustic activity of the whales. The acoustic data were further combined with data from oceanographic models and the results indicate there is no single parameter explaining the variation, although the acoustic activity has weak correlation with rainfall patterns. The pygmy blue whale call detections also appear to increase during periods of stronger upwelling in Southern Sri Lanka.
An attempt to estimate ship noise effect on humpback whales in Japan
Authors: Akamatsu Tomonari , Okamoto Ryosuke , Mori Kyoichi , Mitani Yoko , Tsujii Kouki , Tsuchiya Toshio , Kijima Takahiro , Umeda Naoya
Published: November 2016

Ocean noise pollution is getting to be a major issue for the environmental assessment of maritime transportation and engineering. Evidences to estimate the effect of noise on marine creatures are urgently required. A Japanese team consist of government agency, universities, and research institutions launched a new project to observe possible effects of ship noise on humpback whales in Ogasawara archipelago. Radiated noise from a ship was measured according to the ISO standard protocol in deep water. The position and operational conditions of the ship during the daily voyages were precisely monitored onboard. Sound field within 10 km from the voyage route was calculated by numerical simulation. In parallel, land-based visual observers tracked humpback whales by a theodolite to locate surface position so that the exposure level at the animal can be estimated. Two autonomous stereo recording systems were deployed in the focal area to monitor the phonation behavior of singing whales simultaneously. As the first year result, temporal termination of song sequence was occasionally observed although avoidance behavior from the ship was not quite clear. This project would[NU1] last two more years to provide a scientific evidence of the minimum exposure level to elicit behavioral reaction of the whales.
Noise field characterization in the habitat of the East Taiwan Strait Indo-Pacific Humpback Dolphin during the pile driving activity of demonstration offshore wind farm
Authors: Chen Chi-Fang , Guan Shane , Chou Lien-Sian , Wei Ruey Chang , Hu William W. , Wu Jeff C. , Chen Nai-Chang , Hwang Wei-Shien , Lin Sheng-Fong , Lin Derrick
Published: November 2016

The Eastern Taiwan Strait (ETS) population of Indo-Pacific humpback dolphin (Sousa chinensis) is listed critically endangered in the Red List of Threatened Species by the International Union for Conservation of Nature due to its small population size and narrow distribution. The humpback dolphin habitats off the coast of Miaoli and Changhua are sites selected for future wind farms, therefore, the noise impact of pile driving on this critically endangered population is expected to be serious. This paper presents works done in (1) characterizing the sound field during the test pile driving and associated activities in the humpback dolphin habitat; (2) identifying dominant anthropogenic noise sources of the dolphin habitat during the construction of demonstration wind turbines and associated activities; and (3) examining the implications of the sound field from wind turbine construction and associated activities in relation to humpback dolphins’ hearing and communication. The results from the study can provide critical information and conservation recommendations for an environmental impact analysis for the full scale wind farm construction in 2017.
Enhanced chondrocytes growth in 3-D alginate scaffolds with improved porosity and permeability induced by low intensity pulse ultrasound
Authors: Tu Juan , Guo Xiasheng , Zhang Dong , Ma Qingyu , Guo Gepu , Xu Huan
Published: November 2016

Recent development in applications of new biomaterials and biomedical engineering enable the tissue engineering to become a promising cartilage repair technique. Here, a 3-D alginate scaffold was fabricated by a cross-linked method. Experiments were performed to investigate how the porosity and permeability of the 3-D scaffold, as well as the proliferation rate of seeded cells, were affected by the ultrasound exposure parameters. The scanning electron microscopy and fluorescence imaging were used to examine the micro-structure, porosity, and permeability of the scaffolds, and biochemical analyses were applied to assess the cell growth in the scaffold. The optimum low intensity pulsed ultrasound (LIPU) driving parameters that benefit the enhancement of scaffold porosity and cell proliferation were also explored. The results suggest that, for the scaffold exposed to LIPU, its porosity and permeability could be significantly enhanced by the increasing LIPU amplitude, which might be induced by the microstreaming shear stress generated by ultrasound-driven microbubble oscillations. The assessments of cell proliferation and collagen II expression confirmed that, with appropriately selected LIPUS driving parameters, chondrocytes growth could be effectively promoted in 3-D alginate scaffolds treated by LIPU, because of the improved scaffold porosity and permeability might benefit cell growth space and nutrition supply.
Robust and high-frame-rate visualization of arterial pulse wave propagation dynamics
Authors: Yu Alfred C. H. , Chee Adrian J. Y. , Yiu Billy Y. S.
Published: November 2016

Crucial to the facilitation of early detection of vascular diseases is the development of new imaging techniques that can track vascular dynamics at sub-millisecond time resolution. Previously, we have designed new high-frame-rate ultrasound imaging solutions that can track complex flow dynamics at >1000 fps frame rate, thereby providing hemodynamic insights for vascular diagnostics. Here, we have expanded our suite of vascular diagnostic tools by developing new imaging modes for mapping the structural dynamics of arterial walls. We have particularly devised a novel framework for robust ultrasound-based mapping of the spatiotemporal dynamics of arterial pulse wave (PW) propagation. Our framework involves: 1) plane wave data acquisition; 2) eigen-based data processing; and 3) phase-based motion estimation. The eigen-processing module represents a novel application of singular value decomposition, and its purpose is to isolate the desired forward PW through identifying the corresponding left singular vector through a frequency analysis algorithm, thus making our framework robust against the biasing impact of PW reflections. Also, to visualize PW propagation, positions of PW front were mapped and trailed with its past positions. Using this new eigen-based PW visualization framework, we can now accurately identify differences in PW propagation dynamics in arterial segments of different wall thicknesses and wall elasticity. Corresponding cineloops will be shown at the meeting.
Ultrafast plane-wave imaging of ocular anatomy and blood-flow
Authors: Silverman Ronald H. , Ketterling Jeffrey A. , Urs Raksha
Published: November 2016

Ophthalmic ultrasonography is currently performed virtually exclusively with mechanically scanned, focused single-element transducers. This technology provides B-scan images at approximately 10 frames/s and does not offer any capacity for imaging or measurement of blood-flow. Conventional linear array systems often exceed FDA guidelines for ophthalmic exposure, especially in Doppler modes. Plane-wave techniques offer both ultrafast imaging and reduced acoustic intensity, since no focusing is performed on transmit. Using a 128-element, 18 MHz linear array, we adapted compound coherent plane-wave techniques for imaging ocular anatomy and blood flow at up to 20,000 frames/s. We measured acoustic intensity at the elevation focus and demonstrated conformance to FDA ophthalmic guidelines. We imaged human subjects and visualized blood flow by acquiring data continuously for at least one cardiac cycle. By applying a singular value decomposition filter to the spatiotemporal covariance matrix, we formed color-flow images and measured flow velocity over the cardiac cycle in the major retrobulbar vessels, choroid and anterior segment, including the iris and ciliary body. Given the major role of blood flow in diseases such as glaucoma, macular degeneration, diabetic retinopathy, and tumors (among others), this technique offers an important new diagnostic capability in ophthalmology not available using current ophthalmic B-scanners or optical coherence tomography.
Bio-inspired broadband sonar array prototypes and underwater experiments for two- and three-dimensional acoustic imaging applications
Authors: Gaudette Jason E. , Donskoy Dimitri M. , Martin Caleb J. , Murphy Christin T. , Simmons James A.
Published: November 2016

Underwater sonar imaging relies upon the information contained in time correlation delays across numerous channels. Designing higher resolution imaging systems currently requires increasing the array aperture to wavelength ratio (L / λ), where L is the effective array length and λ is the acoustic wavelength in the medium. This fundamental constraint leads engineers down the path of adding a significant number of channels to a sonar design, which in turn increases array complexity and cost. Our research in bio-inspired sonar has revealed an approach that circumvents this constraint by exploiting bandwidth in addition to time-delay for the angular imaging process. Presented will be the results of a 2-channel underwater prototype tested in an acoustic tank and design work toward a 3-channel prototype for extending imaging to elevation angles. This work represents ongoing efforts toward developing a compact, low-cost broadband underwater sonar for near- to mid-range imaging and classification. Future integration with an autonomous underwater vehicle will demonstrate this technology for simple obstacle detection and avoidance of complex objects. [Work supported by ONR and internal investments by NUWC Division Newport.]
An ultrasound focusing lens design incorporating high transmission and minimum diffraction
Authors: Guo Xiasheng , Lin Zhou , Guo Gepu , Tu Juan , Ma Qingyu , Zhang Dong
Published: November 2016

An improved design of ultrasound focusing lens is reported, in which a periodical array of grooves were carved on the surface of a conventional lens. With vibrations produced by a planar wave transducer coupled to the lens’s left surface, each groove could be treated as a point source as long as the groove widths are much smaller than the acoustic wavelength. Several uncommon acoustic effects (e.g., collimation and enhanced acoustic transmission) have been incorporated into the designing, providing the benefits ranging from transferring acoustic energies, suppressing the side-lobes, and minimizing shifting of the focal point. It is demonstrated theoretically and experimentally that acoustic focusing achieved by using the lens can suppress the relative side-lobe amplitudes, enhance the focal gain, and minimize the shifting of the focus. The application of the corrugated lens can make a reduction of about 3 dB in the relative side-lobe amplitudes, a 3.6-dB increase in main-lobe amplitude, and reduction or even elimination of the focus shift which could be enormously valuable in enhancing the safety of noninvasive HIFU therapy. Enlarging the number of grooves could even further enhance the capabilities of improving the focusing efficiency and reducing the relative side-lobe amplitudes.
The acoustical performance of an ultrasound matrix transducer directly stacked on a silicon chip
Authors: Shabanimotlagh Maysam , Raghunathan Shreyas , Jong Nico d. , Verweij Martin D.
Published: November 2016

Clinical studies have shown a high demand for 3D real time ultrasound imaging for accurate diagnosis. One way to scan a volume with high frame rate is to design a 2D matrix transducer allowing beamforming in both lateral and elevation directions. Recent developments in manufacturing technologies allow the integration of a matrix of piezoelectric elements on Application Specific Integrated Circuit (ASIC). The ASIC is responsible for beamforming, amplification, switching, and significant channel count reduction. Traditionally, the backing material for a linear/phased array is composed of a mixture of epoxy with powder of heavy materials, which causes strong attenuation. This avoids energy being reflected back into to the elements and results in short pulses, high bandwidth, and consequently high axial resolution of the image. However, the ASIC acoustically behaves like a hard and non-absorbing backing material. Therefore, the acoustical energy of the piezoelectric pillar propagates into the chip and affects the performance of the neighbouring elements. In this paper we numerically investigate the effect of the ASIC on the acoustical performance of a transducer. In particular, the transmit and receive performance, crosstalk, and directivity pattern are compared with the results for a traditional backing material.
A micromachined low frequency microphone based on a field effect transistor and an electret
Authors: Shin Kumjae , Kim Junsoo , Lee Hoonteak , Seo Donghwan , Moon Wonkyu
Published: November 2016

Recently, several Internet of Things (IoT) devices using low-frequency acoustic sound have emerged as promising sensor applications. Unfortunately, the detection of low-frequency sound using miniaturized microphones is restricted due to the low cut-off frequency of capacitive type transduction. To overcome this limitation, a micromachined microphone based on a field-effect transistor (FET) and an electret was reported and its feasibility as a low-frequency microphone was demonstrated in 2015. However, the proposed microphone was realized by bonding two chips mechanically and the FET was embedded in a membrane, which was disadvantageous for sensitivity enhancement. To realize stable highly sensitive modulation, we devised and fabricated a structure in which the electric field due to an electret embedded in the membrane modulates the channel of the FET. The acoustic signal causes the electret mounted on the membrane to vibrate, which changes the distance between the channel of the FET and the electret. The resulting change in the electric field modulates the conductivity of the channel. The use of an electret embedded on the membrane makes it possible to detect the displacement of the membrane directly and enhances the sensitivity of the microphone. Its feasibility as a low-frequency microphone will be examined experimentally.
Acoustic lens with exponential horns for selective distant recording
Authors: Kobayashi Maho , Takahashi Yoshinori
Published: November 2016

Many signal processing techniques for sound source separation using microphone array have been studied as a robust audio recording method to ambient noise. However, the implementation in real-time is still hard to be realized in terms of its large computational cost. As an another approach, a directional microphone has a capability to record sound from a specific direction; however, it is impossible to pick up sound at a specific distance. As a part of research on acoustic transducer, on the other hand, a method to broaden the directivity by using the slant-plate acoustical lenses at the front of loudspeaker has been utilized. In addition, there is a report that a slant-plate acoustical lens combined with a conical horn shows a sharper directivity than that by a parabolic microphone. The authors have studied selective distant recording using acoustic lens that synchronously adds the wave fronts after removing the time difference of arrival via the speaking tubes having different lengths. As a result of that the shape of the speaking tube in the acoustic lens was replaced with exponential horn, an improvement in terms of sound quality with a reduction of resonance was obtained.
Evaluation of spherical microphone baffle with six hollows for omnibinaural recording
Authors: Imamura Kento , Nishino Takanori , Nakagiri Taishi , Naruse Hiroshi
Published: November 2016

A binaural recording system records binaural sounds corresponding to plural listening orientations simultaneously. We devised and evaluated the binaural recording system. A binaural recording is generally performed with a dummy head; however, it can record for single listening orientation only. Moreover, an easy binaural recording system is desired because the dummy head is big, expensive, and difficult to handle. Therefore, we devised a cheaper and smaller omnibinaural recording system. In previous research, a spherical microphone baffle with two hollows was proposed, and the results addressed that it could be considered as a binaural recording system. In this study, a microphone baffle with six hollows was designed and evaluated. The proposed baffle has a spherical shape. Six hollows are located on three orthogonal axes originated from the center of the baffle. The acoustical features were examined by the numerical analysis. The results show that a difference between the previous research and the proposed baffle is small and the proposed baffle can achieve an omnibinaural recording.
A new standard for transduction materials
Authors: Logan Roger M.
Published: November 2016

A proposal has been made to establish a new (ANSI) standard to replace MIL-STD-1376B (cancelled). This presentation will expand on this proposal and provide a rough outline as a possible starting point for such a standard. Feedback and discussion will be encouraged.
Development of anti-cavitation hydrophone using a titanium front plate: Durability test in the high intensity focused ultrasound field
Authors: Shiiba Michihisa , Okada Nagaya , Takeuchi Shinichi
Published: November 2016

Our research group has developed new anti-cavitation hydrophones by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film with 15 μm thickness on the back surface of a titanium front plate with 50 μm thickness and 3.5 mm diameter. A durability test of the anti-cavitation hydrophone was performed when the anti-cavitation hydrophone under test was placed at the focal point of a concave focused ultrasound transducer with 100 mm diameter and at a resonant frequency of 1.75 MHz. The amplified 80 Vp-p (calculated electric input power: about 40 W) signal was applied to the concave ultrasound transducer at the focal point of the focused ultrasound system and high-intensity ultrasound waves were irradiated in water. The irradiated sound pressure at the focal point was about 4 MPa. Through this research, we will report that the fabricated new anti-cavitation hydrophone was robust and was not damaged easily, even in a high intensity focused ultrasound field with sound pressure of where acoustic cavitation occurred. We will make a durability test by increasing the acoustic power at the focal point of the focused acoustic field with sound pressure higher than 15 MPa.
Sound recording using optical marker-based motion tracking system: Relation between various constraints
Authors: Song Min-Ho , Godøy Rolf I.
Published: November 2016

Optical marker-based motion tracking system is the device that can record the motion of moving object using multiple high-speed infrared (IR) cameras. Recent development of the motion capture device enables capturing the detailed motions with high spatial precision of sub-millimeter and high sampling rate up to 10 kHz. Currently, the motion tracking cameras can record the local vibrating movement of an acoustic instrument, which makes it possible to retrieve sound from the visual domain. In this study, two constraints in using marker-based motion tracking cameras for the sound recording are discussed. One is the temporal constraint where high sampling rates cause the detectability problem of the retro-reflective marker. When the cameras are operated with high speed, the cameras cannot radiate sufficient IR light and makes it hard to detect. The other is the amplitude constraint where the low camera calibration accuracy increases the signal-to-noise ratio. The effect of these constraints is observed using professional motion tracking cameras (Qualisys) and their relations over various physical conditions will be given.