bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of electrolarynx controlled by real-time statistical F0 prediction
Authors: Tanaka Kou , Toda Tomoki , Nakamura Satoshi
Published: November 2016

One of the major speaking methods for laryngectomees is a speaking method using an electrolarynx to generate artificial excitation sounds, instead of vocal fold vibration. Although electrolaryngeal (EL) speech is relatively intelligible, its naturalness is quite low owing to the artificial excitation sounds. To make it possible to produce more naturally sounding EL speech, we have proposed an automatic control method of the fundamental frequency (F0) patterns of the excitation sounds generated from the electrolarynx based on real-time statistical F0 prediction. In this method, a vibration of the electrolarynx to generate the excitation sounds is controlled not according to additional signals consciously provided by the laryngectomees but using only their produced EL speech signals. In the previous report, we have developed a prototype system by implementing our proposed method to the electrolarynx and have evaluated its performance objectively through a simulation. In this paper, we evaluate its performance subjectively in terms of naturalness and intelligibility. The experimental results demonstrate that the prototype system can produce more natural EL speech while maintaining its high intelligibility compared to the conventional electrolarynx. [This research was supported in part by JSPS KAKENHI Grant Nos. 15J10727 and 26280060.]
Generative model of spectra for a word using Fujisaki’s model and genetic algorithm
Authors: Takara Tomio , Higa Akichika
Published: November 2016

Fujisaki’s model is a generative model of fundamental frequency which approximates original time pattern effectively. In this study, we propose a new generative model of spectral sequence using Fujisaki’s model. We have already proposed a speech synthesis method using vowel space parameters. The vowel space parameter is defined as the component on principal axis obtained by PCA for log-amplitude spectra of isolated vowels. Log-amplitude spectrum can be reconstructed from linear combination of a few principal vectors with coefficients of the vowel space parameters. Using time sequence of the vowel space parameters, we can synthesize a spoken word. In this study, we apply Fujisaki’s model to the time pattern of vowel space parameter. We adopt parameters of Fujisaki’s model as genes of the genetic algorithm. Then, we execute the genetic algorithm with the fitness of similarity between time patterns of Fujisaki’s model and the pattern generated from the vowel space parameter. We obtained synthesized speech which can be recognized as a spoken word at the first generation of the genetic algorithm. As a result of listening test for vowels showed 45 to 80% correct rate at the first generation. Consequently, the effectiveness of the proposed method is shown.
Evaluation of natural language understanding based speech dialog interface's effectiveness regarding car navigation system usability performance
Authors: Kojima Takahiro , Kaminuma Atsunobu , Isoyama Naoya , Guillaume Lopez
Published: November 2016

Recently, new cell phone services enable taking input by speaking to a quasi-agent using highly accurate speech recognition technologies. However, there are two problems when equipping a vehicle with these technologies. First, we do not understand yet the effect on driver’s usability performance of a car navigation system equipped with spoken dialogue interface. Second, the corresponding design techniques to obtain sufficiently good navigation results has not yet been determined. In this study, we first discuss problems involving speech recognition technologies and the types of speech interface used in this study. Second, we experimentally compare in pseudo-driving conditions the effect on driver’s physiology of various speech user interfaces: the Command Input (CI) interface, the Natural Language Understanding (NLU) interface, and the NLU/Spoken Dialogue Management (SDM) interface. According to the analysis of physiological signals, parasympathetic nervous system activity index value was higher when using the NLU/SDM interface than when using the CI interface. Furthermore, both subjective assessment result and time satisfaction degree of NLU/SDM interface were higher than others. Therefore, we can conclude that the NLU/SDM-type interface has better usability performance.
Infinite impulse response inverse filters based on system identification with singular value decomposition
Authors: Samejima Toshiya , Mitsuyasu Kento
Published: November 2016

The authors propose infinite impulse response (IIR) inverse filters for equalizing non-minimum phase acoustic plants through accurate system identification. System identification of an acoustic plant is an essential and important process in designing a controller for the plant, such as an inverse filter. In the previous paper, one of the authors has introduced the singular value decomposition (SVD) method for system identification of an enclosed sound field. The SVD method, which is the state space model-based system identification technique, involves the characteristics of experimental modal analysis. The author has verified that the SVD method has several advantages, such as high precision of identification. The proposed IIR inverse filter is simple inversion of the transfer function of the accurately identified model of an acoustic plant through the SVD method. The poles outside the unit circle in the z-plane, which are originated with the non-minimum phase zeros of the identified plant, are reflected toward the inside of the unit circle. The proposed IIR inverse filter is applied to enclosed sound field equalization. It is demonstrated that the proposed IIR inverse filter can achieve lower equalization error or lower order of the inverse filter than conventional inverse filters using the least squares method.
Stereo channel music signal separation based on non-negative tensor factorization with cepstrum regularization
Authors: Seki Shogo , Ohtani Kento , Toda Tomoki , Takeda Kazuya
Published: November 2016

Music signals are usually generated by mixing many music source signals, such as various instrumental sounds and vocal sounds, and they are often represented as 2-channel signals (i.e., stereo channel signals). Underdetermined source separation for separating the music signals into individual music source signals is a potential technique to develop various applications, such as music transcription, singer discrimination, and vocal extraction. One of the most powerful underdetermined source separation methods is Nonnegative Matrix Factorization (NMF) that models a power spectrogram of an observation signal as a product of two nonnegative matrices; basis and activation matrices. To apply NMF to the stereo channel music signal separation, we have proposed Nonnegative Tensor Factorization (NTF) by further implementing a gain matrix to represent mixing (i.e., panning) information. However, the separation performance of this method is insufficient owing to less prior information to model acoustic characteristics of the individual music source signals. To address this issue, we propose a cepstrum regularization method for NTF to make power spectral envelopes of the separated signals close to those of individual music source signals. We conduct experimental evaluations to investigate the effectiveness of the regularization method and show remaining problems to be addressed.
An investigation into bio-inspired sonar search performance
Authors: Edwards Joseph R. , Beery Sara , Railey Kristen E.
Published: November 2016

The ability to detect, localize, and recognize objects on or under the seafloor is a critical capability for missions such as mine countermeasures (MCM), asset recovery, and feature-based navigation. Unmanned undersea vehicles (UUVs) have been increasingly tasked with such missions and are becoming more capable as technology develops. One intended application of developing UUV technology is to replace the dolphins that execute the mine-hunting task in the U.S. Marine Mammal Program. UUV development for MCM has moved toward larger vehicles with more powerful and multi-modal sensors, to the point where next-generation UUVs are significantly larger and have more powerful sensors than the dolphins they are intended to emulate. Dolphins rely on relatively modest sonar to detect and locate bottom and buried mines, but utilize it to great effect. In contrast to rigid UUV search instructions, dolphins employ a flexible approach with respect to both sonar characteristics and search trajectory. In this work, the effectiveness of biomimetic sonar search is investigated through four principal axes of adaptation: click interval, source power, source center frequency, and mobility. It is shown that the introduction of limited flexibility in the sonar search can greatly improve the overall area clearance performance.
Modeling the acoustic response of elastic targets in a layered medium using the coupled finite element/boundary element method
Authors: Abawi Ahmad T. , Krysl Petr , Espana Aubrey , Kargl Steve , Williams Kevin , Plotnick Dan
Published: November 2016

The fluid-structure interaction technique provides a paradigm for solving scattering from elastic targets embedded in a fluid by a combination of finite and boundary element methods. In this technique, the finite element method is used to compute the target’s elastic response and the boundary element method with the appropriate Green’s function is used to compute the field in the exterior medium. The two methods are coupled at the surface of the target by imposing the continuity of pressure and normal displacement. This results in a boundary element equation that can be used to compute the scattered field anywhere in the surrounding environment. This method reduces a finite element problem to a boundary element one with drastic reduction in the number of unknowns, which translates to a significant reduction in numerical cost. In this talk, the derivation of the technique will be outlined; the method will be applied to compute scattering from various targets, including unexploded ordnance (UXO) in complex ocean environments and the results will be compared with measurements.
Relation between children’s calmness and sound environment in nursery field: Influence of environmental settings and childcare practice
Authors: Noguchi Saki , Ueno Kanako
Published: November 2016

In Japanese childcare facilities, there has conventionally been a serious problem regarding too noisy environment in nursery room. This becomes even more serious in an urban area having high population density, particularly because of lack of childcare space. It is concerning that sound environment in childcare facilities, where children live for approximately 8-11 h, has a great influence on the mental and physical development of children. The relation between children’s calmness, such as a state of relaxation or concentration on activity, and the sound environment is reported herein, with a view to creating a suitable sound environment for children. We explain this relation in terms of environmental factors and childcare practices using the following cases. (1) Experiment conducted by varying the environmental settings— particularly, spatial reverberation and furniture of play corner; (2) observation of the childcare practice attached great importance to create the calm of sound environment. From the result, we report the influence that sound environment has on children’s calmness and discuss methods to ensure that the sound environment supports healthy development of children.
Modeling of venues for music practice and instruction
Authors: Jaramillo Ana M. , Olson Bruce C.
Published: November 2016

Music practice rooms for large groups are spaces with conflicting requirements, especially those that are part of schools. The need for an environment that is similar to the ones where the musicians will be performing (appropriate reverberation for music performance), and on the other hand, the need for music instruction (speech intelligibility for teacher/student and student/student communication) are usually opposing. As part of a renovation of band rooms in two schools, we were called to advise on the room acoustics. The rooms were having floor replacement, from carpet to tile and needed to have the room acoustics reviewed and adjusted for the new floor material with added wall or ceiling absorption to replace what was lost from the floor.
Experimental measurements of word intelligibility among pre-school children under differing conditions of reverberation and signal-noise ratio
Authors: Harada Kazunori , Kawai Keiji
Published: November 2016

Many children, from 0 to 5 years old, spend most of their active hours in child day-care centers. Rooms in these centers are often very noisy, due to both the voices of children or sounds of various activities and to the excessive reverberation attributable to the little use of sound-absorbing materials. Some researchers have studied the speech intelligibility of elementary school children, but we were unable to find those of pre-school children. Thus, in this study, an experiment was carried out a word intelligibility test on children from 3 to 5 years old in a classroom of a child day-care center. The procedure was like a game. Each of the presented words was mixed with pink noise at one of two S/N ratios, and convolved with the impulse responses of three reverberation times of 0.3, 0.9, and 1.8 s. Children were asked to judge whether the word was food or not, and to raise their hands holding yes or no signs. As a result, the correct answer ratio for 3-year-old children was lower than the ratio for other groups. Also, the correct answer ratio for 4- and 5-year-old children was slightly lower than control groups of elementary school pupils and college students.
Effect of design on acoustic performances in classrooms: Case study from Ankara
Authors: Kocyigit Filiz B.
Published: November 2016

Education is one of the most important factors for the development of societies. Efficient education can be possible with a qualified communication. Current spaces are huge factor that effects communications. No doubt that auditory comfort in spaces with completed acoustic development provides better communication. This study is prepared to propound the effects of the acoustic comfort conditions in classrooms which are the educational structure’s most important spaces and the material used. Within the scope of this study, two schools which are private and government high school in Ankara situated in Cankaya Municipality have been chosen to make measurements. Selected schools have been researched by the classes’ volume in terms of compliance with acoustic and in accordance with the inner surface of equipment. Similar volume classes chosen in both schools and they are measured with acoustic measuring devices, RT, EDT, C80, D50, STI, and RASTI which are significant for the intelligibility of speech has been taken into consideration for evaluation of the measurements taken in the determined classes. The impacts of furniture and surface materials on the acoustic comfort conditions are recovered in renewed or newly designed classrooms for revealing the most ideal level of speech intelligibility in classes.
Comparison of laboratory building acoustics standards from ASTM International, Japanese Industrial Standards Committee, and the International Organization for Standardization
Authors: Golden Matthew V.
Published: November 2016

Testing standards are fundamental to the practice of building acoustics. To that end, ASTM International, the Japanese Industrial Standards (JIS) Committee, and the International Organization for Standardization (ISO) all have standards that cover the laboratory measurement of airborne and impact sound transmission. These standards include ASTM E90 and E492, JIS A 1416, and A 1418 and ISO 10140. This paper will review the theory behind each methods and the derivation of the equations used. It will also discuss each of these standards in detail, including the relative strengths and weaknesses of each as well as the interoperability the resulting data. Previous research comparing the standards will also be reviewed. Finally, a brief overview of the repeatability and reproducibility of all building acoustics standards will be discussed.
Test and rating method comparison between Japan and the U.S. for airborne sound insulation in buildings
Authors: Masuda Kiyoshi
Published: November 2016

The Japanese test methods for laboratory measurement of airborne sound transmission loss for building partitions are basically the same as the American test methods. However, the two countries’ field test methods for airborne sound insulation in buildings differ. The octave band sound pressure level difference between two rooms is the most significant value for the field evaluation of sound insulation in Japan, whereas the apparent transmission loss for a partition installed in a building is the most popular value for the field evaluation of sound insulation in the US. Why is the octave band sound pressure level difference popular in Japan? It is the basic way of thinking in Japan that an acoustical engineer should take responsibility for the total spatial sound insulation performance, including sound absorption and flanking transmission from the design stage to completion and the field test and evaluation method as the completion inspection should be simple. If the insulation performance does not meet the specific criterion at the time of its completion, it is necessary for the acoustical engineer to demonstrate the cause of the insulation defect using various measurement techniques, including test methods similar to FTL in ASTM E336.
Reverberation time versus volume for active acoustic systems
Authors: Schwenke Roger W. , Szuts Tobi
Published: November 2016

If two rooms have the same reverberation time but different cubic volumes, then they will differ in acoustic strength. Many authors have presented recommendations for reverberation time as a function of volume for different purposes. There are many parameters that, if held constant, yield different reverberation times for different cubic volumes: strength, clarity, critical distance, etc. For example, the ITU-R BS.1116 recommendation for reverberation time versus volume corresponds to rooms of constant average absorption per square meter. This paper will review the literature on reverberation time versus volume, show the connection between STI and reverberation versus volume, and propose a recommendation for reverberation versus volume for active acoustic systems.
Significance of terminal frequency in FM sweeps for bat echolocation
Authors: Riquimaroux Hiroshi
Published: November 2016

For echolocation of CF-FM bats, the CF component is expected to detect wing-beat of flying insects. However, it also plays an important role to serve as a stable signal carrier from a distant target. Then, once the carrier frequency is removed, echo signal can be easily detected. For this purpose, Doppler-shift compensation and echo amplitude compensation must be conducted to stabilize the signal carrier. What about the FM bats? FM bats also appear to utilize a relatively long pseudo-CF component to detect wing-beats of flying insects. They might also utilize pseudo-CF component for an echo signal carrier. However, Doppler-shift compensation in FM bats has not been reported. In the inferior colliculus, majority of neurons are tuned to the pseudo-CF frequency, 20 kHz for Eptesicus fuscus while 40 kHz for Pipistrellus abramus, which are corresponding to the terminal frequencies of downward FM sweep. Overrepresentation of a particular frequency may enhance frequency discrimination, detection of insect wing-beat. Therefore, we may expect majority of cochlear nerve fibers are also tuned to the pseudo-CF frequency. However, overrepresentation of hair cells for a particular frequency does not appear to be shown. [Research supported by MEXT, Japan and Shandong University, China.]
Signal characteristics and echolocation challenges of Mexican free-tailed bats during high-speed flight
Authors: Kloepper Laura , Linnenschmidt Meike
Published: November 2016

Female Mexican free-tailed bats (Tadarida brasiliensis) form large maternal colonies numbering up to several million. After their nightly emergence and feeding, they return to the roost from high elevations and speeds nearing 100 km/h. At these speeds, the bats should experience, among other things, difficulties in object distance encoding due to the large distance travelled before echo returns and significant Doppler shifts to their echoes. Further, they face navigational challenges from nearby conspecifics. In this study, we characterized the acoustics of returning Mexican free-tailed bats and investigated for possible Doppler shift compensation during various flight speeds. Synchronized acoustic and thermal imagery recordings were conducted at several caves across multiple mornings during cave re-entry. Call sequences for individual bats were extracted for different flight speeds, and changes in call parameters were compared within each call sequence. First basic analysis indicates a possible lack of Doppler shift compensation during fast and steep re-entry flights. Further, these bats demonstrate a flexible signal design and extreme behavioral maneuvers in flight.
Auditory-visual information transfer in echolocating Egyptian fruit bats
Authors: Schilling Corinna , Grinnell Alan , Metzner Walter
Published: November 2016

Egyptian fruit bats have good vision but can also accurately echolocate relying on their well-developed auditory system. We asked two questions: 1. Can these bats acquire a mental image of an object using vision (or hearing) alone? 2. If such a mental image has been formed, can it be transferred from one sensory modality (e.g., vision) to another (e.g., hearing)? We trained the bats to first localize a rewarded object (an X) that was presented pseudo-randomly at either the left or right side using either vision (group 1) or hearing (group 2) alone. After only a few weeks, all experimental bats were able to perform these tasks. We then had the bats discriminate between a rewarded object (the X) and an unrewarded object (a circle) using either vision (group 1) or hearing (group 2) alone. Again, all bats mastered this task after only a few weeks of training. Finally, we tested if the same bats could also discriminate the objects using the other sensory modality (group 1: hearing; group 2: vision). After only a few sessions, the bats performed correctly suggesting that the bats can indeed transform a mental image that they obtained using one sensory modality to another modality.
Integration of emitter and receiver dynamics in a biomimetic sonar head
Authors: Caspers Philip , Müller Rolf
Published: November 2016

Horseshoe bats (family Rhinolophidae) transmit and receive sonar information about the environment using morphologically complex and dynamic noseleaf and pinnae. Both local shape features and dynamic deformations of the noseleaf and pinnae contribute to properties of the bat biosonar system. This work systematically explores the effect of local shape features on the dynamic properties of emission and reception baffles using a biomimetic robotic system inspired by the horseshoe bat. Parametric models of the greater horseshoe bat (Rhinolophus ferrumequinum) noseleaf and pinnae with selectable combinations of local shape features were developed. Baffles with feature realizations were cast out of flexible silicone and mounted to a platform to dynamically actuate the emission and reception baffle surfaces with motions patterns similar to the greater horseshoe bat. Motions of the baffle surfaces were synchronized to the outgoing and incoming sonar waveform, and the time-frequency properties of the emission and reception baffle realizations were systematically characterized across spatial direction—individually and jointly. Different feature combinations of the noseleaf and pinnae local shape features were ranked for overall dynamic effect. It was found shape and motion patterns impacted the overall dynamics with relative strength over time, frequency, and spatial direction.
Jamming avoidance by the echolocating bat during flight with multiple conspecifics
Authors: Hase Kazuma , Kadoya Yukimi , Maitani Yosuke , Kobayasi Kohta I. , Hiryu Shizuko
Published: November 2016

It remains mystery how echolocating bats extract their own echoes from an acoustic jamming caused by vocalizations of multiple conspecifics flying together. Here, we first successfully recorded echolocation pulses of each animal during four-bat group flight by individually mounted on-board microphones, allowing us to assess vocalization in a jamming environment. We used Miniopterus fuliginosus which emit downward frequency-modulated (FM) ultrasounds. The bats experienced both single and group flights in an experimental chamber. As a result, each bat of the group significantly expanded differences in terminal frequency (TF) of pulses from the neighboring bat from 0.6 ± 0.6 (mean ± SD) kHz in single flight to 1.2 ± 0.6 kHz in group flight (Tukey’s HSD test, P < 0.05). Although the difference in TF observed in group flight was much smaller than the bandwidth of pulses (approximately 40 kHz), computation of cross-correlation providing an index of similarity of two signals demonstrated that the difference is useful to distinguish own signal from others. These results suggest that innate FM signal of bats is jamming-tolerant, and FM bats flying in group highlight differences in TF to avoid or reduce jamming from conspecifics in a closed space, as implied by previous studies.
Twenty five happy years in ocean acoustics
Authors: Munk Walter
Published: November 2016

25 happy years in ocean acoustics
Shallow water acoustics and oceanography at the Woods Hole Oceanographic Institution over the last quarter century
Authors: Lynch James , Duda Timothy F. , Lin Ying-tsong , Newhall Arthur
Published: November 2016

Shallow water (coastal) acoustics has been a topic of great interest over quarter century, both from the point of view of learning coastal oceanography and of learning coastal acoustics. Indeed, the two are difficult to separate. In this talk, the research done at the Woods Hole Oceanographic Institution (very often in collaboration with other institutions) over the past 25 years will be discussed, with an emphasis on the major experimental efforts that have been fielded, but also including theoretical and computational efforts. The Barents Sea Polar Front experiment, the Shallow Water Acoustic Random Medium experiment, the Shelfbreak PRIMER experiment, the Asian Seas International Acoustics Experiment, the Shallow Water 2006 experiment, and the Quantifying, Predicting and Exploiting Uncertainty program are some of the at-sea efforts to be discussed. Theoretical advances in shallow water acoustics, as well as computational efforts, such as the Integrated Ocean Dynamics and Acoustics project, will also be treated. Directions for future work will be discussed.
Inspirations of past leaders in Acoustical Oceanography: Reflections of our roots in AO and bioacoustics
Authors: Stanton Timothy K.
Published: November 2016

I had the privilege of knowing the leaders of Acoustical Oceanography (AO) during its early years, first as a topical entity, then when it was eventually formalized as a Technical Committee (TC). I first arrived at the University of Wisconsin in 1980 and did research there with Clarence Clay for eight years as a scientist. The 1977 book, “Acoustical Oceanography” by Clay and (Hank) Medwin, had recently been published and was required reading. At around the same time, Van Holliday, David Farmer, Mike Buckingham, and Medwin, established AO as a formal committee, first as a Specialty Group (Medwin as Chair), and later as a TC in 1991. Buckingham was elected first Chair of the AOTC and, given the anticipated challenges in starting a new TC, I was made Alternate Chair to work alongside Buckingham on many things. Clay and Holliday inspired much of the AO bioacoustics research that I have conducted, including developing acoustic scattering models, physics-based echo statistics, and broadband acoustic methods to use sound to characterize marine organisms such as fish and zooplankton. I will tell some stories and give examples of recent scientific advances that are traceable to Clay and Holliday.
Passive acoustical oceanography
Authors: Siderius Martin
Published: November 2016

Acoustical Oceanography includes the use of both active and passive acoustic systems to measure various properties of the ocean environment. Active methods use a specifically designed and controlled sound projector while passive methods exploit naturally occurring ocean sounds such as breaking waves, ship noise, or marine mammal vocalizations. Historically, active methods have been the preferred choice when precise propagation times or calibrated sound levels are important. However, passive sensing has a strong appeal due in part to the ease in which listening-only systems can be deployed. There have been a number of advances in passive sensing even for cases where propagation times and sound levels are of interest. For example, it has been shown that surface wave noise can be used to measure vertical propagation times through the seabed and water column. More recently, there is experimental evidence that indicates noise correlations may also be used to determine horizontal propagation times in the seabed. Although replacing controlled projectors with noise sources is an attractive option there are limitations to how and when noise can be used this way. These limitations as well as experimental and modeling results from surface and ship noise will be described in this presentation.
The depth dependence of ambient noise in deep ocean trenches
Authors: Barclay David R. , Buckingham Michael J. , Bevans Dieter
Published: November 2016

A series of experiments aimed at measuring the power spectrum and vertical and horizontal noise coherence (directionality) in the deep ocean were carried out between 2009and 2015 using a family of autonomous instrument platforms named “Deep Sound.” Deep Sound is a free-falling acoustic recorder designed to descend from the ocean’s surface to a pre-assigned depth where it drops an iron weight and returns to the surface under its own buoyancy, while recording pressure time series on four hydrophones with vertical and horizontal spacing over the bandwidth 5 Hz—30 kHz. The complete vertical noise profile was recorded from the surface to 6 km in the Philippine Sea, 8.5 km in the Tonga Trench, and 9 km in the Serena and Challenger Deeps in the Mariana Trench. Generally, the vertical noise coherence is well described by the Cron & Sherman surface noise model with some depth-dependence explained by seawater attenuation and local sound speed variations. Below the reciprocal or critical depth (depth at which the sound speed is higher than any sound speed above it), the total noise field statistics depend heavily on the relative contributions of locally generated surface noise and distantly generated propagating noise. Thus, the depth dependence of the sound field varies with local surface conditions, with nearly depth-independent noise power and coherence found at moderate states, while a sharp drop in noise level is found below the critical depth during calm sea states.
Development of three-dimensional photoacoustic imaging system using sparse array sensor
Authors: Shiina Tsuyoshi , Kondo Kengo , Toi Masakazu
Published: November 2016

Photoacoustic (PA) imaging offers better spatial resolution of ultrasound for deep imaging with high optical contrast sensitive to physiological parameters such as the oxygen saturation of hemoglobin. We have conducted development of photoacoustic mammography system in Kyoto University/Canon joint research project supported by MEXT. In addition, we are promoting development of 3D-PA technologies to be applicable in wider clinical field and non-medical purposes in ImPACT program supported by cabinet office of Japan from 2014. Three-dimensional imaging is required to trace a vessel structure. However, the number of receiving channels is limited due to hardware restrictions. In such a sparse configuration, artifacts due to grating lobes become dominant. A scanning transducer suppresses grating lobes, which virtually increases the number of channels. However, it degrades temporal resolution and causes motion artifacts. We employ a compressed sensing (CS) technique to reconstruct a PA image from limited channels and bandwidth. Due to the computational cost for large 3D calculations, most CS approaches reconstruct PA images in a 2D slice. In order to reduce the cost while maintaining accuracy, we proposed 3D-PA reconstruction using CS based on k-space algorithm. The feasibility of proposed method was validated by simulation analysis and the experimental results.
Volumetric multi-spectral optoacoustic tomography for high performance structural, functional, and molecular imaging
Authors: Razansky Daniel
Published: November 2016

Optoacoustic (or photoacoustic) imaging is an emerging hybrid modality that can deliver excellent endogenous and exogenous optical absorption contrasts from living tissues with excellent spatio-temporal resolution. Our state-of-the-art implementations of multi-spectral optoacoustic tomography (MSOT) are based on multi-wavelength excitation of tissues to visualize specific molecules within opaque tissues. As a result, the MSOT technology can noninvasively deliver structural (i.e., vascular anatomy, solid tumors, and organs), functional (i.e., total hemoglobin concentration, hemoglobin oxygen saturation, blood flow, pH, and metabolic rate of oxygen consumption), and molecular information from living tissues. For highly sensitive molecular optoacoustic imaging, a valuable tool for personalized medicine, exogenous contrast agents (e.g., organic dyes, metallic and nonmetallic nanoparticles, reporter genes, or fluorescence proteins) with biomarkers are commonly utilized. The talk will further introduce the new realm of 5-dimensional (5D) optoacoustic imaging, which enables simultaneous acquisition of information across all the three spatial dimensions, the time and the spectral (optical wavelength) dimensions. Applications are explored in the areas of functional neuro-imaging, fast tracking of agent kinetics and biodistribution, cardiovascular research, monitoring of therapies, and drug efficacy, as well as targeted molecular imaging studies. Clinical translation roadmap will be finally discussed.
Skin vasculature imaging by acoustical resolution photoacoustic microscope with parabolic array transducer
Authors: Saijo Yoshifumi , Nagaoka Ryo , Ul Haq Israr , Siregar Syahril , Takagi Ryo , Yoshizawa Shin , Umemura ShinIchiro
Published: November 2016

Photoacoustic (PA) signal is highly dependent on the structure of the target. In the present study, PA imaging system with parabolic array transducer for multi-angle detection is developed and the skin vasculature is observed. The transducer was consisted of 256 ch 1-3-composite elements with the center frequency of 10 MHz. The diameter was 42.4 mm and the opening angle was 90 degree. A hole was made in the center of the transducer for transmission of the laser. PA signal was acquired by a programmable ultrasound data acquisition system with the sampling frequency of 60 MHz. A diode laser with the wavelength of 532 nm, pulse width of 8 ns, pulse energy of 5 mJ, and repetition frequency of 10 Hz was equipped for generation of PA signal. Three dimensional image was reconstructed by delay-and-sum beamforming of PA signals received by all channels. The frame rate for displaying x-y, y-z, and x-z images was 10 Hz, and the full width at half maximum (FWHM) of the x-z image was 70 μm. 3D structure of the skin capillary network of a human hand was successfully observed by the system. The system may contribute to the peripheral blood circulation.
Reconstruction of vasculature in optical resolution photoacoustic microscopy using wavelet and Hessian based method
Authors: Ul Haq Israr , Nagaoka Ryo , Siregar Syahril , Saijo Yoshifumi
Published: November 2016

Photoacoustic microscopy is a high-resolution and high- contrast function modality where optical absorption is detected by ultrasonic transducer. The noise generated by the detector due to its size, sensitivity make the photoacoustic images difficult to visualize. Denoising and reconstruction of vascular structures is crucial for the early diagnosis and therapy in many medical applications. Therefore, the accurate detection of blood vessels has a great significance to assist the users including radiologists and clinicians by making them visualization of the vascular information in the images. In the proposed method, use of wavelet filtering to enhance the effect of smaller and bigger vessels in Optical Resolution Photoacoustic Microscopy (OR-PAM) is analyzed. The proposed method uses the wavelet to enhance the vasculature and then Hessian based method is applied to classify the vessel-like structures. For the evaluation, the algorithm is tested on photoacoustic images acquired non-invasively from living mouse brain, human finger cuticle, and blood filled tube, which shows appreciable results to enhance vasculature in photo-acoustic imaging.
The acoustic noise pressure of sensors with very small apertures
Authors: Leinders Suzanne M. , de Jong Nico , Verweij Martin D.
Published: November 2016

For medical diagnostic modalities like intravascular ultrasound (IVUS) and intravascular photo acoustics (IVPA), it is paramount to have small, sensitive ultrasound elements for detecting the reflected pressure pulses. The development of one and two dimensional arrays for such applications will call for even smaller element sizes and advanced microfabrication techniques. In search for miniature receiving elements we developed an optical ultrasound sensor with an optical strain detector integrated on a thin acoustical membrane [Leinders et al., Sci. Rep. 5, 14328]. To predict the lowest detectable pressure, we wanted to determine the noise level of this sensor. Unlike a piezoelectric sensor, the noise in our sensor is not dominated by the electrical impedance and will only be caused by the thermo-acoustical noise of the sensor’s internal mechanical impedance, and the noise caused by thermally agitated medium particles that hit the sensor surface. To expand the existing knowledge, we will analyze both noise mechanisms and show that in thermodynamic equilibrium these give rise to the same noise pressure at the sensor surface. Moreover,we will show that for sensors with vanishing aperture area, the noise pressure will reach a well-defined finite limit, and not go to infinity as predicted by some literature.
Cavitation-enhanced diagnostics and therapy in HIFU treatment
Authors: Matsumoto Yoichiro
Published: November 2016

Medical applications of ultrasound such as High Intensity Focused Ultrasound, Extracorporeal Ultrasound Lithotripsy and Ultrasound-Mediated Gene Transfection have recently been the subject of much interest. In these applications, acoustic cavitation facilitates the medical treatment by improving the image quality and enhancing the therapeutic effects through acoustic emission, localized heating, and erosion. During the ultrasound therapy, it is important to control the focal region on the targeting area, which is moving by the respiratory motion, for the reliable treatment. Ultrasound guide is one of the effective way to track the targeting area compensating the respiratory motion. Cavitation-enhanced diagnostics is useful to obtain the clear image of targeting area utilizing the acoustic emission from the existing micro bubbles during the cavitation-enhanced HIFU where cavitation bubbles are generated at the targeting area to enhance tissue heating. In all these applications, it is essential to understand the cavitation phenomena, including bubble and bubble cloud dynamics. The bubble motion and bubble cloud behavior are strongly influenced by the thermal phenomena inside and outside bubbles and the applied ultrasound wave forms which accelerate therapeutic effects by the cavitation bubbles. In this paper, some fundamental aspects of medical application of microbubbles and acoustic cavitation are highlighted.
Numerical study on cavitation-enhanced thermal and mechanical effects in high-intensity focused ultrasound therapy
Authors: Okita Kohei , Matsumoto Yoichiro
Published: November 2016

Cavitation is becoming increasingly important in therapeutic ultrasound applications such as diagnostic, tumor ablation, and lithotripsy. The behavior of cavitation bubbles is resulted by the complex interactions between bubble oscillation and ultrasound. That depends on not only the exposure parameters of ultrasound but also the physical properties of surrounding tissues and injected microbubbles which are often employed as cavitation nuclei for decreasing cavitation threshold pressure and for controlling cavitation region. An ultrasound simulator treating cavitation/microbubble has been developed for investigating the influences of various parameters in the cavitation-enhanced HIFU therapy. The simulator takes into account the heat generation due to oscillating cavitation bubbles as well as the rectified diffusion which is important role in the initial stage of cavitation bubble growth. Bubble dynamics equation considers the elasticity of the surrounding tissue and the shell of microbubbles, and is strongly coupled with mixture phase to reproduce the interaction between ultrasound and bubble oscillation. Thus, the simulator can reproduce cavitation bubble growth from nuclei around focus. In the present paper, the numerical results for the cavitation/microbubble-enhanced HIFU therapy are shown.
Acoustic cavitation sub-millisecond signal processing for ultrasound surgery
Authors: Gerold Bjoern , Anquez Jeremie , Yon Sylvain
Published: November 2016

Cavitation in Focused Ultrasound Surgery (FUS) is a stochastic phenomenon that can evolve very rapidly at the high intensities typically employed. Cavitation activity can be monitored analyzing its acoustic signals in the frequency domain. Cavities act as strong scatterers of incident acoustic energy, potentially enhancing different therapeutic effects, e.g., thermal or mechanical, if properly controlled. We report on the development on an instrument capable of controlling acoustic cavitation at sub-millisecond speed. The cavitation noise signal has been recorded and processed by an FPGA coupled with a feedback loop, capable of modulating the driving field every few hundreds of microseconds to maintain an ideal level of cavitation activity and differentiate between several types of cavitation and the onset of boiling. The system has been tested in tissue phantom, ex-vivo tissue and in-vivo and the impact on lesion sizes has been analysed. We also used the experimental data as input for a non-linear simulation of the acoustic field specifically regarding the absorption/scatter ratio in the acoustic focus. [The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/under REA grant agreement n° (623608).]
Elimination of therapeutic ultrasound noise in phase modulated high intensity focused ultrasound treatment
Authors: Takagi Ryo , Iwasaki Ryosuke , Yoshizawa Shin , Umemura Shin-ichiro
Published: November 2016

Ultrasound image-guided High Intensity Focused Ultrasound (HIFU) has been become one of the potential surgical techniques for the treatment of the malignant tumor. The ultrasound image during the treatment is severely corrupted by the reflected HIFU wave because HIFU and imaging transducers are simultaneously activated. In our previous study, a new method to selectively eliminate only HIFU noise during the treatment was suggested, but it cannot sufficiently reduce the HIFU noise when the HIFU exposure is phase-modulated with a period less than a few milliseconds. In this study, a new method to selectively eliminate the HIFU noise even when the HIFU exposure is modulated with a certain modulation period. In this study, “multiple HIFU exposure” with a certain modulation period was employed. The focus of HIFU was moved every 25μs sequentially for six positions with spacing proper for thermal conduction. the RF signals of the same modulation period were received with (RF2) and without (RF1) transmitting an imaging pulse, respectively. The HIFU noise was eliminated by subtracting RF1 from RF2. As the result of in vitro study, the fundamental to higher harmonic components of the HIFU noise were reduced by 20 to 30 dB during the HIFU exposure.
A portable transcranial focused ultrasound system for non-invasive applications in small animals
Authors: Anastasiadis Pavlos , Nguyen Ben , Hersh David S. , Guo Sijia , Gullapalli Rao , Frenkel Victor
Published: November 2016

Recent studies using focused ultrasound (FUS) have shown significant progress in the realm of brain applications. These transcranial exposures include localized ablation for the treatment of movement disorders and opening of the blood brain barrier to enhance the delivery of therapeutic agents. Whereas these procedures require expensive, MRI-guided systems, one of the newest and most promising applications of FUS being developed involves more portable, hand-held devices for the purpose of neuromodulation. Here, we describe the development of table-top FUS system comprised of a single element FUS transducer (400—600 kHz) specifically for investigations on the stimulation and suppression of neuronal activity in rodents. The transducer assembly includes a cone and extending flexible bolus filled with degassed water for direct coupling to the head of the animals. A custom 3D stage and two diametrically opposed lasers allow for accurate positioning and targeting. Experiments included simulations of the acoustic field using a k-space time-domain method. Localization of the focal zone and its radial and axial dimensions were obtained via thermal exposures in polyacrylamide gel phantoms containing heat sensitive proteins. Last, hydrophone measurements with various sized rodent skulls enabled determination of the expected attenuation to be encountered for future in vivo animal treatments.
Effects of the tempo of background music on prospective and retrospective duration of a video program
Authors: Nishimura Akira
Published: November 2016

To improve understanding of the effects of music on perception of video productions, subjective duration of a video program was measured in the paired-comparison paradigm using a 10-s video program selected from a 70-s daily news program mixed with a 90 beats-per-minute (bpm) music as a reference. Seven video programs were used for comparison, with actual durations ranging from 8.5 s to 11.5 s in steps of 0.5 s. These programs were selected randomly from the same video program and mixed with music played at 50, 90, and 140 bpm. Seven participants listened to a pair of video programs and then answered which program of the two was subjectively longer. The psychometric functions of retrospective perception of duration showed that video programs mixed with the fast-tempo music were perceived as short. In addition, five other participants were asked to prospectively produce a 10-s interval on a stopwatch while watching the same video programs. The actual times recorded generally exceeded 10 s, and were significantly long for the program mixed with slow-tempo music. The conflict between the results obtained from the two experiments on subjective duration and its relation to the fixed physical duration is discussed in terms of internal clocks.