bluuebunny/crossref_metadata_2025 huggingface dataset:
Scatterometry for nanoimprint lithography
Authors: Zhu Ruichao , Brueck Steven R. J. , Dawson Noel , Busani Tito , Joseph Praveen , Singhal Shrawan , Sreenivasan S. V.
Published: November 2016

Angular scatterometry is used to characterize the nanostructure parameters of two samples: a high dielectric contrast ∼100-nm period Al wire-grid polarizer (WGP), and a low dielectric contrast ∼130-nm period photoresist grating on a flexible polycarbonate substrate; both fabricated by nanoimprint lithography. The zero-order diffraction (reflection) is monitored for a large incident angle range from 8° to 80°. For the WGP, four wavelengths (244-, 405-, 633-, and 982-nm) are used to study the dependence of the scatterometry parametric determination as a function of the sample pitch to wavelength ratio (p/λ: 0.41–0.1). A 4-nm thick native Al2O3 layer was added to the scatterometry simulation and dramatically improved the cross-correlations between results at the different wavelengths. For the photoresist samples, the scatterometry results at 405 nm are compared with atomic force microscopy measurements and the master grating structure. The scatterometry results are sensitive to inhomogeneity of the sample and show a capability for classifying different types of macroscopic defects.
Ab initio study of the trimethylaluminum atomic layer deposition process on carbon nanotubes—An alternative initial step
Authors: Förster Anja , Wagner Christian , Schuster Jörg , Friedrich Joachim
Published: November 2016

Electronic applications of carbon nanotubes (CNTs) require the deposition of dielectric films on the tubes while conserving their excellent electronic properties. In our density functional theory study, the authors use the trimethylaluminum (TMA) atomic layer deposition (ALD) as a model process for a CNT-functionalization. Since this functionalization relies on the presence of OH-groups, the CNTs are exposed to a water or oxygen pretreatment. The authors show that only CNTs with a single-vacancy defect are able to react with H2O or O2. Further, the defect is preferably saturated by oxygen. This leaves the CNT without the necessary hydroxyl groups for the first TMA addition. Therefore, the authors propose an alternative initial step after which a classical TMA ALD process can be performed on the CNT.
Cartilage conduction hearing-The third sound conduction pathway
Authors: Hosoi Hiroshi
Published: November 2016

Hosoi found in 2004 that a clear sound can be heard when a vibration signal is delivered to the aural cartilage from a transducer. This form of signal transmission is referred to as cartilage conduction (CC). Then, we have examined its mechanism, application, and superiority over the well-known air or bone conduction (AC or BC). We have published 11 English articles including JASA by 2016. AC, BC, and CC are distinguishable according to two points, namely, transmission media and movement of the skull bone. The transmission media are sound in AC, vibration in BC and CC. The movements of the bone are immobile in AC and CC, vibrated in BC. The world first CC hearing aids have been completed. It is very useful for the patients who cannot wear regular hearing aids because of atresia of external auditory canals, for example. More useful applications are cell phones and robots. The CC cell phone has a lot of advantage such as 1) easy volume control without button operation, 2) insulation from outer noise and obtaining the best S/N instantly, 3) no sound leakage to outward, 4) clean liquid crystal display, 5) easy to use even with hearing aids, 6) better suited for very small body type cell phone, and all that. There is no disadvantage compared with the regular phone. Various types of cell phone can be realized using CC. For example, wrist watch type, pen type, eye glass type, finger ring type, etc. Also, CC will give the good method to communication between robots and human beings.
Information-theoretic assessment of the peripheral dynamics in the biosonar system of horseshoe bats
Authors: Müller Rolf , Gupta Anupam , Zhu Hongxiao , Pannala Mittu , Gillani Uzair S. , Fu Yanqing , Caspers Philip , Buck John R.
Published: November 2016

Horseshoe bat biosonar is characterized by a pronounced dynamics at the interfaces of ultrasound emission and reception: The bats can alter the shapes of their noseleaves and outer ears (pinnae) through muscular action while they are emitting or receiving biosonar signals. An information-theoretic analysis has been conducted to assess whether these non-rigid baffle motions could affect the ability of the bats' biosonar system to encode sensory information. This analysis was based on acoustic characterizations (beampatterns) obtained either through numerical predictions or from measurements of physical models. In total, four time-variant baffle shapes, for emission and reception, numerical and physical each, have been analyzed. The similarity of beampattern across different baffle shape conformations was quantified using normalized mutual information that was found to be <20% for distant stages. Hence, the changes in the baffle shapes were capable of providing different views of a biosonar environment. The information added by these views was found to enhance performance bounds for sonar estimation tasks related to target direction. In particular, it was found that the number of resolvable directions and the accuracy of direction-finding (as measured by the Cramer Rao lower bound) increased when beampatterns from across a sequence of shape conformation were combined.
Tools for education in acoustics and phonetics
Authors: Arai Takayuki
Published: November 2016

We have developed a series of tools for education in acoustics and phonetics. Some of them are in electronic form, while some are physical models. A set of demonstrations and explanations in acoustic phonetics is now available as “Acoustic-Phonetics Demonstrations (APD)” through our WebSite: www.splab.net/APD/. We are adding content and have made YouTube video clips using physical models available on our WebPages. In particular, we use the physical models of the human vocal tract to demonstrate acoustic phenomena and theories. They are useful tools for explaining acoustics in speech production, such as the source-filter theory and the relationship between vocal-tract configurations and vowel quality. Furthermore, the models are effective when teaching articulation/pronunciation of native and non-native languages. Due to the high demand for vocal-tract models of various sounds in multiple languages, we are expanding the range of sounds to include more than Japanese sounds, but also additional vowels and consonants in different languages, including English. We also discuss how to apply three-dimensional printing.
Sharpness perception and modeling of stationary and time-varying sounds
Authors: Sottek Roland
Published: November 2016

Psychoacoustic parameters like loudness and sharpness can be used for sound quality assessment and sound design applications. While loudness of stationary sounds has been standardized for decades, standards for sharpness of stationary sounds and loudness of time-varying sounds have only been published since 2009 (DIN 45692:2009-08) and 2010 (DIN 45631/A1:2010-03), respectively. Present calculation methods of sharpness consider the “center of gravity” of the weighted specific loudness patterns as a measure for sharpness; thus, their results do not depend on loudness. Only the Aures model includes, to a small extent, the influence of loudness on sharpness by an additional loudness-dependent factor. Until now, mostly stationary synthetic sounds (filtered noise and pure tones) have been used for the derivation of sharpness models. However, when these calculation procedures are applied to generally time-varying technical sounds, the results deviate significantly from the listening test results. This study describes new listening tests performed to investigate systematically the influence of loudness as well as temporal structures on sharpness. The findings from the listening tests should serve as a basis for an improved model of sharpness perception for stationary and time-varying sounds.
Improved understanding of head-related transfer functions through sagittal-plane spectral decomposition
Authors: Romigh Griffin D. , Brungart Douglas S. , Simpson Brian D.
Published: November 2016

Head-related transfer functions (HRTFs) capture the listener-specific modifications that are imparted on a sound as it travels from a specific location in space, interacts with the listener’s head, shoulders, and outer ears, and arrives at the ear drums. HRTFs have often been decomposed into a combination of two parts to aid modeling and analysis: a diffuse-field transfer function (DFTF) that captures non-directional but still listener-specific spectral details of the HRTF, and a directional transfer function (DTF) that captures all of the listener-specific directional information. Because the DTF contains spectral variation along all spatial dimensions, it does not provide a way to separate the spectral cues responsible for lateral and sagittal plane localization judgments, which are largely independent. As an alternative approach, decomposing an HRTF along each sagittal plane (aka along the “cones-of-confusion”) provides similar benefits to DTF analysis while providing additional insights into the spectral cues responsible for lateral and vertical localization, independently. This talk will provide a detailed overview of sagittal-plane spectral decomposition along with experimental results showing how the technique can be applied to improve localization with non-individualized HRTFs, separate general and idiosyncratic HRTF features, and cluster listeners’ HRTFs based on spectral similarity.
Roles of spectral peaks and notches in the head-related transfer functions in the upper median plane for vertical localization
Authors: Iida Kazuhiro , Ishii Yohji
Published: November 2016

The parametric head-related transfer function (HRTF) recomposed of only a spectral peak (P1) generated by the first resonance of the pinna and two spectral notches (N1 and N2) generated by the first and the second anti-resonances of the pinna has been reported to provide approximately the same localization performance as the measured HRTF for the front and rear directions. However, for the upper directions, the localization performance for some of the subjects decreased. In the present study, we carried out two localization tests with seven target vertical angles in the upper median plane to clarify whether adding a spectral peak (P2) generated by the second resonance of the pinna can resolve this performance decrease. The results suggested the following: (1) N1, N2, and P1 play an important role in vertical localization; (2) localization performance was improved by adding P2 to N1N2P1 at the upper directions; (3) however, a sound image was hardly perceived in the upward direction by reproducing only P2, P1, and P1 + P2; and (4) P2 could be utilized to enhance N1 at the upper direction.
Modelling of dynamic behaviour of viscoelastic materials in the frequency domain
Authors: Pritz Tamás
Published: November 2016

The modern methods of acoustical and vibration calculus require accurate material models to take properly into account the damping and dynamic elastic properties of the viscoelastic materials used for sound and vibration control. The usual modeling methods (spring-dashpot models, fractional calculus) start out of the stress to strain relations defined in the time-domain, which are then transformed into the frequency domain to find the appropriate material functions. In contrast, the damping and elastic properties are known from measurements made in the frequency domain; therefore, it seems to be reasonable to model the material behavior directly in this domain. The aim of this paper is to show that the typical dynamic behavior of solid viscoelastic materials can efficiently be modeled in the frequency domain. This modeling method is based on simple theoretical considerations, the frequency domain experiences and the causality principle. Two fundamental material models are developed in this way, namely one for the damping increasing with frequency, and the other one for the damping peak, which can be either symmetrical or asymmetrical with respect to the logarithmic frequency. The relation of the frequency domain models to the popular fractional derivative models defined in the time-domain is shown and discussed.
Numerical simulation for low frequency noise from viaduct by the vehicle load
Authors: Kamiakito Noboru , Shimura Masayuki , Iwabuki Hiroshi , Osafune Toshikazu
Published: November 2016

There is the case that the low frequency noise generated complaints of neighborhood residents from the road viaduct. We tried to clarify the source of low frequency noise using the FEM model as one approach for such a problem. First, the 3D-FEM model of the vehicle, bridge, and air was constructed. Then, propagating of the acceleration was calculated by the vehicle traveling on viaduct with road irregularities. Then, the vibration velocity of the viaduct is radiated as sound pressure, and propagating of the sound pressure through the air was carried out by 3D-FEM calculation. Actually, a numerical model for the viaduct that caused the complaint was constructed. The low frequency noise generation mechanism was investigated. The effective measures was considered. As a result, it became clear that a high reduction effect of low frequency noise by performing the measures road irregularities can be obtained in the viaduct. It became clear that there is the acoustic radiation of low frequency noise by the sound insulation wall on the viaduct. By carrying out the parameter study using such a method, we can clarify the occurrence factor of the low frequency noise.
Urban seismology: Numerical results and real data observations on the clustering effect of buildings
Authors: Colombi Andrea , Gueguen Philippe
Published: November 2016

Seismic design parameters for buildings are traditionally based on the seismicity of the area, the so-called site effects, and structural response decoupling with the underlying surface. It is however well known that buildings strongly affect the wavefield interacting in a non-linear way through the foundations and the surrounding soil. In dense urban areas, buildings are very close to each other, and it is reasonable to expect a collective effect known as site-city interaction (SCI). Initially, observations of this phenomenon have been made difficult by the lack of data. Now, the increased availability of continuous records from permanent seismic networks in urban areas or buildings has made SCI an important topic in urban seismology. Here, after presenting some numerical results of SCI in densely built areas, we discuss a recent study on three residential towers located in the city of Grenoble (France) exhibiting an SCI that depends on the strike angle of the seismic energy. Both numerical simulations and recorded data exhibit dynamic coupling within the building cluster that has a non-negligible impact on the building response. The angle dependence helps interpreting the tenants’ answers to a survey made right after the Earthquake in each of the tower.
Feasibility study on synthesis of English vowels with a vocal tract mapping interface
Authors: Aoki Riku , Ogata Kohichi , Taruguchi Akihiro
Published: November 2016

This paper describes the synthesis of English vowels with a vocal tract mapping interface developed in our laboratory. This interface uses five vocal tract shapes that are located at apexes of a pentagonal chart in consideration of Japanese vowels. It allows users to configure the vocal tract shape corresponding to the location of the mouse pointer based on interpolation. Moreover, it has a function of the inverse estimation of the vocal tract from formant frequencies. Although the interface has been developed considering the Japanese vowels, whether English vowels can also be synthesized with this interface is an interesting topic for confirmation of its versatility. Therefore, we investigated the feasibility of producing English vowels ([ɑ], [æ], [ɔ], [ɛ], [ɝ], [i], [I], [u], [ʊ], [ʌ]) with the mapping interface. As the first step, we investigated that the mapping interface could estimate vocal tract shapes for the English vowels synthesized with the VowelEditor in Praat as test sounds. Furthermore, listening tests were conducted to examine whether the re-synthesized vowel sounds with the mapping interface were matched with the original vowel sounds by Praat. The experimental results showed that the mapping interface has a potential for producing English vowels.
Speech resynthesis from 1/f
β
noise
Authors: Fuhrman Robert , Vatikiotis-Bateson Eric
Published: November 2016

Speech can be resynthesized from acoustic parameters estimated from the motion of the vocal tract articulators, head, and face. This has shown that speech information is broadly distributed both in space and time across the physiological systems associated with speech production, and correspondingly, it provides a basis for exploring what properties of signal structure are relevant for specifying the relation between acoustics and physiology. In this presentation, we use the resynthesis paradigm to explore the extent to which the acoustic-articulatory relation can be specified in terms of the structure of fluctuations in the speech signal. Specifically, we demonstrate that speech acoustics closely matching the original can be obtained by replacing the vocal tract kinematic signals typically used in the re-synthesis paradigm with surrogate signals having 1/fβfractal fluctuation structure—a known (Voss & Clarke 1975) statistical property of the speech amplitude envelope that holds for low frequencies corresponding to the rate of articulatory motion (<10 Hz: Dudley, 1939). We also address the hypothesis that quantitative descriptors derived from both the fractal and multifractal properties of speech link the time-varying properties of speech acoustics to the cooperative motion of physiological structures involved in speech production.
Improving Spanish speech synthesis intelligibility under noisy environments
Authors: Lorenzo-Trueba Jaime , Barra-Chicote Roberto , Yamagishi Junichi , Montero Juan M.
Published: November 2016

In this paper, we evaluate a newly recorded Spanish Lombard Speech database. This database has been recorded with expressive speech synthesis in mind, and more particularly adaptability to the environment. Real stationary noise recorded inside of a car was used to produce the Lombard speech response in the speaker by means of a headphone. Four different noise levels were used, in steps of 5 dB and also clean speech to set the clean speech baseline. Finally, a pair of intelligibility evaluations were carried out, one with natural speech that proves the validity of the recorded database by showing a 37% absolute increase in intelligibility in a -10 dB SNR condition when compared to non-Lombard speech. The second evaluation was carried out with synthetic speech, which showed a 10% absolute increase in intelligibility for both the -10 and -15 dB SNR condition.
Many-to-many voice conversion using hidden Markov model-based speech recognition and synthesis
Authors: Aizawa Yoshitaka , Kato Masaharu , Kosaka Tetsuo
Published: November 2016

This paper describes a many-to-many voice conversion (VC) technique that does not require a parallel training set of source and target speakers. In a previous study, we already proposed many-to-one VC method that consists of decoding and synthesis parts, and it does not require a parallel training set. The basic idea of this system is that an input utterance is recognized utilizing the hidden Markov model (HMM) for speech recognition, and the recognized phoneme sequences are used as labels for speech synthesis. The aim of this work is to extend functionality from many-to-one to many-to-many VC. In particular, we focus on the VC of emotional speech. In order to achieve this, we utilize speaker adaptation techniques to adapt HMMs for speech synthesis. By using adaptation techniques, an arbitrary speaker’s voice can be produced. In this work, a combination of constrained structural maximum a posteriori linear regression and maximum a posteriori estimation is used for adaptation. In order to evaluate the proposed system, subjective speech intelligibility tests were conducted. In the experiments, the proposed adaptation with 10 utterances was compared with traditional parameter training with 450 utterances. The results showed that speaker adaptation could be carried out without performance degradation.
Noise reduction for sound capturing by creating spatial null sensitivity point
Authors: Ando Akio , Yamauchi Kodai , Onishi Kazuyoshi
Published: November 2016

We had developed a sound source separation system in which two microphones had been arranged in a line toward sound sources to form null sensitivity points at the source positions by solving the weighting coefficients for microphone outputs. The system achieved the sound source separation by excluding non-target sound sources, instead of extracting target sound sources. In this study, we propose the sound capturing system by which the user can set the null sensitivity point at the arbitrary position. The null sensitivity point is formulated as a function of the weight coefficients. The gain function is also defined as a function of a spatial position. The proposed system uses these functions to capture the target sound while suppressing the non-target sound. A computer simulation showed that, instead of a null sensitivity point, the proposed system generated the circular null sensitivity area whose center was at the microphone position.
Development of unsupervised classifier for beaked whale clicks
Authors: Sidorovskaia Natalia , Li Kun
Published: November 2016

Recent advancements in passive acoustic monitoring lead to the collection of large volumes (hundreds of Tb) of acoustic data, which are post-processed to identify various acoustic events. One of the processing goals is the identification of deep diving marine mammal calls, including different species of beaked whales (Gervais', Blainville's, Cuvier's, etc.) Traditional detectors employ a band-energy-based approach to search for acoustic events above baseline level in the click production band. However, such detectors have a large percentage of false positives and require an experienced operator to manually determine the false positive rate and subdivide the class detections (beaked whales) into species specific calls (such as Cuvier's, etc.) Modern supervised and unsupervised machine learning algorithms broadly employed for the analysis of large volumes of data may open opportunities for the development of highly accurate detectors for marine species with minimal operator involvement. Unsurpervised clustering, supervised classification, and neural networks are implemented as second stage detectors for the classification of species-specific beaked whale calls. Algorithm features, optimization, and performance are discussed. [Research supported by GOMRI.]
Need of good classroom acoustics since the early childhood
Authors: Astolfi Arianna , Puglisi Giuseppina E. , Prato Andrea , Shtrepi Louena , Sacchetti Benedetto , Sacco Tiziana
Published: November 2016

In everyday lives, the listening experiences often occur in adverse listening environments in which children need to tune out competing sounds to tune into speech. In the early childhood and in the first years of education, a good acoustic environment is mandatory in order to avoid difficulties in literacy development. This is true both for normal children and for children with potential learning disabilities, which can be only diagnosed after this age-period. Whenever children with poor neural processing in speech discrimination are exposed to bad acoustics, they may fall behind their peers in reading development. On the contrary, since the neuroplasticity of the auditory cortex of the human brain is up to about the age of eight years, when at-risk children are trained with learning programs based on sound and visual cues recognition in proper listening environments, the effectiveness of these programs is improved. This work focuses on the evidence of the need of good classroom acoustics by the early stage of education. Preliminary results on a study on the influence of classroom acoustics on the reading skills in the early childhood are reported. The study involved 120 second-grade pupils in three primary schools with different classroom acoustics.
Quantitative analysis of rigid and non-rigid motion patterns in rhinolophid and hipposiderid pinnae
Authors: Yin Xiaoyan , Qiu Peiwen , Zhang Mengna , Müller Rolf
Published: November 2016

It has long been noted that horseshoe bats (Rhinolophidae) exhibit large ear motions during biosonar behaviors. Some authors have regarded these motions as rigid rotations of the pinna whereas others have pointed out that the animals are capable of non-rigid motions where the shape of the pinna changes. In the current work, we have analyzed pinna motions in greater horseshoe bats (Rhinolophus ferrumequinum) and the related great roundleaf bat (Hipposideros armiger) to investigate the issue of rigid versus non-rigid pinna motions. The bats were found to produce rigid as well as non-rigid motions. The latter were characterized as “open-close” motions where the size of the pinna aperture was changed by varying the distance between the anterior and posterior rims of the pinna. To quantify this, pinna motions were described by three-dimensional tracking of points on the pinna rims using high-speed stereo vision. The point coordinates were used to compute a matrix that contained the maximum change in distance between any pairs of points on the anterior and posterior pinna rims. Dimensionality reduction methods (e.g., linear discriminant analysis) were applied to the vectors containing all elements of these “maximum distance change matrices” to quantify the relationship between rigid and non-rigid motions.
Twenty five years of learning what acoustics can do for oceanographers
Authors: Farmer David M.
Published: November 2016

From cracking ice and breaking surface waves to stratified flows and turbulence, the ocean reveals its secrets through underwater sound. Some personal experiences will illustrate the remarkable opportunities that flow from collaboration between oceanographers and ocean acousticians.
Studying breaking waves with ambient noise oceanography
Authors: Deane Grant B.
Published: November 2016

Ambient noise oceanography is a powerful tool in the study of breaking ocean waves, yielding insight into the nature of fluid turbulence and air entrainment within whitecaps. Whitecaps limit the height of waves on wind-driven seas, transfer momentum and gasses between the atmosphere and ocean, increase the ocean’s albedo, are a source of marine aerosol and generate underwater ambient noise. For such reasons, the relationship between fluid turbulence and the size distribution of bubbles in whitecaps is of considerable interest, but the interior of whitecaps are quite difficult to study in the field. Large extinction rates associated with high air fractions in whitecaps limit the usefulness of optical and acoustical probes, and few measurements from in situ instrumentation have appeared. However, the sound radiated by newly formed bubbles within whitecaps provides a useful signal, one which can be interpreted in terms of bubble creation rates, provided the bubble emission signature and propagation through the breaking wave crest are understood. A physical model for the generation of wave noise and its use to provide insight into the link between fluid turbulence, its saturation in wave crests, and its relationship to bubble formation will be discussed. [Work supported by ONR Ocean Acoustics Division.]
Real-time, non-contact, non-invasive imaging of elasticity properties in soft tissues using the combination of light and air-coupled ultrasound
Authors: Pelivanov Ivan , Ambrozinsky Lukasz , Song Shaozhen , Yoon Soon Joon , Li David , Shen Tueng , Wang Rikuang , O'Donnell Matthew
Published: November 2016

A new non-contact method for efficient, non-invasive imaging of elasticity in soft media is presented. It uses transient mechanical waves excited in the object under study from air (i.e., non-contact) using either ultra-violet (UV) pulsed laser radiation (photoacoustic) or air-coupled focused ultrasound (US) and resultant displacements detected a high frame rate, phase-sensitive (PhS)-OCT system. UV laser radiation is absorbed in a thin subsurface region of the tissue creating transient mechanical waves due to thermal expansion, whereas the air-coupled focused US beam reflected from the air/medium interface provides acoustic radiation force (ARF) to the medium surface, launching a transient mechanical wave in the transverse (lateral) direction. Real time tracking/imaging of resultant mechanical wave propagation can be used to reconstruct tissue elastic properties. Tissue mimicking phantoms, porcine eyes, and skin were used in ex-vivoexperiments to prove the concept. Results of these experiments strongly suggest that simple, non-contact excitation holds great promise for non-invasive characterization of soft media, in general, and for elasticity measurements in delicate soft tissues and organs (e.g., in the eye), in particular.
All optical frequency domain photoacoustic microscope based on two-wave mixing in a photo-refractive crystal
Authors: George Deepu , Lloyd Harriet , Silverman Ronald H. , Chitnis Parag V.
Published: November 2016

Optical resolution photoacoustic microscopy (OR-PAM) provides functional and molecular information at the cellular scale. OR-PAM typically employs ultrasonic transducers, which require coupling with tissue, to detect the thermo-elastic waves generated in tissues irradiated by nanosecond laser. Images are acquired by scanning the excitation beam, which is usually focused to a spot size of a few microns, i.e., lateral resolution. However, the axial resolution is constrained to an order of magnitude lower by the bandwidth of the transducer used. Additionally, imaging depth of OR-PAM is constrained to the depth that allows ballistic photons, which is usually less than 1 mm. We present an All Optical Frequency Domain Photoacoustic Microscope where the photoacoustic signal is generated by an amplitude modulated CW laser and detected using a two wave mixing (interferometer) in a photorefractive crystal. Sweeping the amplitude-modulation frequency and using an ultra-broadband optical detector can potentially provide detection bandwidths greater than conventional OR-PAM, e.g., 100-200 MHz. The loss in efficiency of photoacoustic excitation associated with violating the stress-confinement condition is overcome by using a lock-in amplifier. This method promises a high-fidelity microscopy system that does not require acoustic coupling while reducing associated costs and footprint. [Work supported by NIH-NEI 1R21EY023012.]
Laser-driven resonance of light-absorbing ultrasound contrast microbubbles
Authors: Lajoinie Guillaume , Lee Jeong Y. , Linnartz Erik , Owen Joshua , Kruizinga Pieter , de Jong Nico , van Soest Gijs , Stride Eleanor , Versluis Michel
Published: November 2016

The sensitivity of ultrasound imaging is greatly enhanced by the use of microbubble contrast agents through resonant volumetric oscillations. While the increased acoustic contrast is of prime interest for perfusion imaging of organs, microbubbles until now have limited benefit in terms of specificity for ultrasound imaging. Original strategies are required to tackle this difficulty that rely on loading functional targeting ligands onto the microbubble encapsulation. In parallel, laser light offers great specificity in its interaction with tissue. This advantage is put to use in photoacoustic imaging where absorbed laser light is converted into a measurable acoustic signal. Here, we present a novel ultrasound contrast agent designed to make use of the specificity of laser light. The acoustic agent consists of a gas core encapsulated by an oil layer containing an absorbing dye. The resulting laser light absorption can then be used to heat up the gas and drive the system into resonance, thereby generating ultrasound. Combining finite difference simulations and ultra high-speed imaging led to a quantitative physical description of the optical and thermal interactions in the system resulting in the efficient generation of acoustic waves in the MHz range. A range of physical bubble parameters are investigated, i.e., thickness and composition of the light absorbing oil layer. This new generation of contrast agents will open up new applications in medical diagnostic and therapeutic imaging.
Visualization of ultrasound fields in a transparent medium with ultrasound attenuation using the focused shadowgraphy technique
Authors: Iijima Yukina , Kudo Nobuki
Published: November 2016

Knowledge of ultrasound pressure fields of ultrasound inside the human body is essential to confirm the safety of medical ultrasound equipment. Typically, pressure waveforms in the body are estimated by correction of those measured in water considering typical attenuation in biological tissues. However, the correction of frequency-dependent attenuation of a wide band pulse is difficult because biological tissues have a non-linear transmission characteristic. In this study, acoustic fields of pulsed ultrasound propagating in a transparent medium with ultrasound attenuation were visualized using focused shadowgraphy (Kudo, Ultrasound Med. Biol. 41, 2071-2081, 2015). Pressure waveforms of the pulsed ultrasound were also measured using a membrane hydrophone. Brightness curves and their 1st-order integrations derived from the visualized field images were compared with the pressure waves. Experimental results obtained by using castor oil demonstrated that the 1st-order integrations of brightness curves are in better agreement with the pressure waveforms. Furthermore, frequency spectrum analysis showed good agreement of attenuation coefficients derived from the pressure waveforms and integrated brightness curves, indicating the usefulness of the technique not only for visualization of ultrasound fields but also for estimation of pressure waveforms and ultrasound attenuation.
On the formation of bubble clusters and tunnels in tissue-mimicking agarose phantoms by focused ultrasound bursts
Authors: Movahed Pooya , Kreider Wayne , Maxwell Adam D. , Bailey Michael R. , Freund Jonathan B.
Published: November 2016

Formation of bubble clusters in soft tissues is a potential injury mechanism in therapeutic ultrasound treatments. To study this phenomenon, transparent tissue-mimicking agarose phantoms were subjected to a series of multiple-cycle ultrasound bursts, using a burst wave lithotripsy (BWL) protocol, and simultaneously imaged with a high-speed camera. The negative pressure in the initial bursts causes preexisting sub-micron bubbles to expand sufficiently to become visible in images (~200 microns). Additional bubbles appear continuously during the subsequent bursts. A Rayleigh-Plesset-type bubble dynamics model, which is generalized to include elastic resistance and damage mechanisms, is developed and used to explain key observations. It is proposed that material fatigue leads eventually to irreversible fracture-like failure. In addition to isolated, approximately spherical bubbles, long tunnel-like features are observed, which seemingly comprise lines of joined bubbles along a possible fracture or defect. Statistics regarding the geometry of these features are reported for agarose phantoms of different stiffness. A mechanism for the formation and observed growth of these long features is proposed, wherein defect/crack growth allows the movement of initially trapped bubbles within the phantom. [Work supported by NIH NIDDK grant DK043881.]
Color-Doppler ultrasound imaging of in situ human kidney stones in a hyperbaric chamber
Authors: Simon Julianna C. , Dunmire Barbrina , Cunitz Bryan W. , Sapozhnikov Oleg A. , Thiel Jeffrey , Bailey Michael R. , Holm James R.
Published: November 2016

Overpressure has been shown to reduce the color-Doppler ultrasound twinkling artifact on ex vivo human kidney stones, leading to the hypothesis that surface crevice microbubbles cause twinkling. For the first time, we investigate the effect of overpressure on in situ human kidney stones. Thus far, five human subjects with kidney stones known to twinkle have been imaged with a Philips/ATL P4-2 transducer and Verasonics ultrasound system for 45 minutes in a hyperbaric chamber. Subjects breathed ambient air while exposed to a maximum pressure of 4 atmospheres absolute (ATA), except for a scheduled decompression stop at 1.6 ATA where subjects breathed pure oxygen. Twinkling was quantified in terms of Doppler power over 2 min intervals before pressurization (baseline), at 4 ATA, and at 1.6 ATA. Preliminary results (averaged over 3 of the 5 subjects) indicate no change in twinkling at 4 ATA compared to baseline levels (ratio of Doppler powers = 1.09±0.27). Twinkling almost doubled, though, during the pure oxygen stage at 1.6 ATA compared to baseline levels (ratio of Doppler powers = 1.85±0.58). The increase in twinkling associated with breathing pure oxygen continues to support the crevice microbubble hypothesis. Higher pressures than explored in this study may be needed to reduce twinkling on in situ stones, as was often the case in studies using ex vivo human kidney stones. [Work supported by the National Space Biomedical Research Institute through NASA NCC 9-58 and NIH grants DK043881 and DK092197.]
Toward treatment of abscesses using non-thermal HIFU
Authors: Brayman Andrew A. , McClenny Anna , Wang Yak-Nam , MacConaghy Brian , Chan Keith , Monsky Wayne , Matula Tom
Published: November 2016

Abscesses are infected walled-off collections of pus and bacteria. They can affect any part of the body. Current treatment is typically limited to antibiotics, catheter drainage and hospitalization, or surgical wash-out when inaccessible, loculated or unresponsive to initial care efforts. Although bacteria can develop drug resistance, they remain susceptible to thermal and mechanical damage. High Intensity Focused Ultrasound (HIFU) generates localized heating and cavitation, and represents a potential new noninvasive treatment modality. This talk describes initial experiments in which non-thermal HIFU treatment was used to inactivate small volumes (100 μL—10 mL) of Escherichia colisuspensions (~1 × 109 cells/mL) with 1 or 2-MHz transducers. Free-field focal acoustic pressures were as high as 16 (9.9) MPa peak positive (negative). Survival was assessed by coliform counting, and by alamarBlue® vital staining. At duty factors of 0.01 or 0.2, and the highest acoustic pressures, there was no biologically significant heating of the exposed samples. Inactivation was treatment time-dependent, and was well described by a half-life model. There was a well-defined (free field-equivalent) acoustic pressure threshold, with significant cell inactivation above ~7 MPa peak negative pressure.
Use of smartphones for introductory acoustics education
Authors: Sakagami Kimihiro , Satoh Fumiaki , Omoto Akira
Published: November 2016

In order to propose an effective method using smartphones (including tablets) of acoustics education for introductory courses of architectural and environmental acoustics in architectural studies, the authors have examined some applications which work on smartphones. As the first step, applications measuring sound level and spectrum at reasonable prices are chosen and their precision have been verified. Results showed that the most iOS devices has somewhat reasonable precision, e.g., for SPL measurement, it is similar to Class 2 sound level meter, though some Android devices give lower precision. Then, the authors introduced these tools to student and encouraged them to use these tools to produce a noise map (with dBA only and with both dBA and sound spectra). Even though these simple tools allow students to understand the relationship between their sensation and physical values. As further studies, the authors also tried to use some more applications which enables students to measure more advanced physical values, such as Band Levels, Leq, Impulse Responses, Reverberation Times, etc. Some examples of the measurement results of them are also presented.
Efficacy of a new spatial ear training program for “Ensemble width” and “Individual source width”
Authors: Imamura Hidetaka , Kim Sungyoung
Published: November 2016

The authors have devised a matching-based training paradigm that assists listeners in evaluating spatial width of a reproduced sound field with increased sensitivity and memory. The program uses a learning paradigm of repeated comparison and match to references. All sound sources were horizontally spread using a pairwise constant power panning law over front five loudspeakers located at + -60, + -30, and 0 degree. Trainees were asked to adjust a parameter controlling the panning intervals of five-channel sound sources until it matched to the perceived width of a given reference. The program provided visual feedback for isomorphic mapping. To make the training equipment more accessible, the headphone version of the program was also developed using a simulation of listener and sound sources positions in a room. Thirty participants were divided into three groups: a group with loudspeaker-based training, a group with headphone-based training, and a group without training. Participants in the trained groups took 6 days training program with 3 to 5 sessions in a day. The difference between reported and presented intervals before and after the training were measured. The analyzed results showed that regardless of training method (loudspeaker- or headphone-based), trained groups showed improvement in their matching precision.
The advanced technique of the counterpoint between music and video in Evangerion: 2.0 You can (not) advance
Authors: Yamada Masashi , Yanagida Riu
Published: November 2016

Film director, Akira Kurosawa, used a technique called the counterpoint between music and video, where a part of a film consisted of incongruent features between the music and motion picture, in his films. Hideaki Anno, a director of animated movies, invented an advanced technique of the counterpoint in his film EVENGERION:2.0 YOU CAN (NOT) ADVANCE. In the present study, the emotions of the music and video, and the congruency between them were measured continuously, to reveal the effects of this advanced technique. The results showed that, in the long last scene, the emotional features of the music were incongruent with the video at first. Then, the emotions of the music gradually coincided with the video. Finally, they became congruent. In the present study, various types of music were presented with the original video, and these versions were also used for the continuous measurements. Moreover, overall impressions of these versions, as well as the original version, were measured. The results showed that the original version was perceived as significantly more preferable and enjoyable than the versions where music was consistently congruent with the video.
Damping contributions of sound absorbing materials in three-dimensional spaces to obtain efficient layouts
Authors: Yamaguchi Takao
Published: November 2016

In this research, we have proposed a method for determining an efficient layout of sound absorbing materials in three-dimensional spaces using damping contributions with eigenmodes as weight coefficients. We use the complex effective density and the complex bulk modulus of elasticity for finite elements of sound absorbing material. We formulate discrete equations using the elements. Solutions to the complex eigenvalue problem of the discrete equations are expanded with a small parameter that is related to the damping. By adopting the first order approximation with respect to the small parameter, we derive the dominant equations of motion. By arranging these derived equations, the contribution of each element to modal loss factors can be obtained in consideration of multiple modes. According to these contributions, the sound absorbing materials are filled in the spaces. In this proposed method, the components of eigenvectors at the evaluation points are used as the weight coefficients for the damping contributions. The weight coefficients play an important role in intensively damping the acoustic modes that exert dominant influences on the sound pressure at the evaluation points. We explain numerical examples to verify the effectiveness of this layout method.
Evaluation of low cost microphone for active noise control in duct
Authors: Lima Pedro Henrique R.
Published: November 2016

Economic feasibility and cost minimizing of experimental setups is oneof the most important factors in many research and this is no different for active noise control (ANC) in ducts. Cheaper acquisition and assembly of equipment is desirable, provided you keep the same efficiency of acquisition, filtering, control, and attenuation. This study aims to compare the performance of low cost microphones with precision microphones, when applied to the acoustic control system in feedforward configuration. This system makes use of a control board with Digital Signal Processor (DSP) in order to identify, analyze, and compare systems of acoustic control in real time. To validate the performance of the sensors, an experimental bench was setup which included a PVC duct and speakers as noise source and actuator. Microphones are the error and reference sensors. The systemperformance is obtained by a sound pressure meter acting on the outlet duct.
Detection of snow avalanche locations using infrasound array data
Authors: Arai Nobuo , Imai Toshiaki , Otsuki Masaya , Saito Yoshihiko , Murayama Takahiko , Iwakuni Makiko
Published: November 2016

Infrasound observation measures the energy radiated by a snow avalanche into the atmosphere and can be used to detect snow avalanches over large areas. Our research team has conducted infrasound observation in Tokamachi, Niigata Prefecture, Japan, during the last three winter seasons. First, between January and April 2013, we deployed an infrasound sensor in front of a selected slope, obtained visual observations using a web camera, and identified infrasound signals generated by snow avalanches. During the second season (2013-2014 winter), we deployed two infrasound sensors approximately 1 km apart and obtained the attenuation characteristics of infrasound signals. In the 2014-2015 winter season, we deployed three sensors spaced at 1-2 km in a triangular array and attempted automatic extraction of signals associated with snow avalanches from observed raw data using time-domain processing. For the extracted signals, the locations of snow avalanches were estimated with the cross-correlation method. Twelve events were detected and located. The estimated locations were in an area with many steep slopes. An infrasound array monitoring system with real-time processing is capable of providing significant information on snow avalanche activity.