bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial acoustic modulator for projecting high-quality holographic image
Authors: Liang Bin , Cheng Jianchun , Zhu Yifan , Zhu Xuefeng , Zou Xinye , Yang Jing
Published: November 2016

Spatial modulation of acoustic wave has demonstrated theoretical and experimental importance in the field of acoustics, with wide applications such as in medical ultrasound and particle manipulation. However, the existing means for acoustic modulation have to rely on the acoustic metasurfaces providing only pure phase modulation or active element arrays with complicated fabrications and limited spatial resolutions. In this work, we present the design, numerical simulation, and experimental demonstration of a spatial acoustic modulator (SAM) capable of manipulating the phase and amplitude profiles separately and continuously, offering the possibility to address the above challenges by enabling arbitrarily complex acoustical patterns. The proposed structure has a simple configuration with planar profile, high efficiency of spatial modulation, and deep-subwavelength unit scale, ensuring easy and low-cost fabrication and nearly-continuous wavefront manipulation. The designed SAM is used to project high-quality acoustic holograms both theoretically and experimentally to demonstrate its wave-steering functionality. Our metastructure-based holographic projector with simplicity and extreme acoustic performance advances the capability of spatial acoustic modulation, and have various applications in places where the conventional techniques would lead to complexity and limited ability.
Shallow water acoustic channel estimation across fluctuations in channel support
Authors: Sen Gupta Ananya
Published: November 2016

Estimating the shallow water acoustic channel across rapidly varying multipath fluctuations have been an open challenge for decades. Recently, sparse sensing techniques have been employed to take advantage of the heavy-tailed distribution of channel components in the Delay-Doppler domain. Despite noticeable improvement over channel estimator performance by exploiting channel sparsity compared to traditional least-squared based techniques, a key challenge remains. Most sparse recovery techniques are designed to estimate high-amplitude components across static or slowly varying support. Depending on wind and sea conditions, the underlying distribution of the channel components may change unpredictably, leading to fluctuations in the channel support that are difficult to model or track efficiently with high precision. Furthermore, not all channel components are high-energy and therefore, may be unintentionally suppressed by a sparse optimization technique. We will present the current state-of-the-art on applying sparse sensing, particularly mixed norm techniques, to shallow water channel tracking. In particular, we will present extensions to prior work on channel estimation that exploit a non-convex metric to converge faster to the same solution offered by the traditional (and convex) Lasso metric. We will present how non-convex optimization can navigate varying channel sparsity and present results based on experimental field data.
Audio spotlight system based on formation of multiple focused sound sources via loudspeakers
Authors: Akamatsu Shuji , Tatekura Yosuke
Published: November 2016

We propose a new audio spotlight system which uses focused sound sources arranged in an arc shape, and we evaluate its suppression performance and frequency responses. Audio spotlight systems use ultrasonic waves to produce sharp directional sounds without any external disturbances. However, such systems contain two problems: (1) low efficiency of the electro-acoustic conversion and (2) distortion of the reproduced sound. Therefore, we attempted to form an audio spotlight system by using focused sound sources based on wave field synthesis. A single focused sound source is designed to harmonize the phase of the driving signal at an arbitrary position. Thus, the driving signals that correspond to the number of the optional focused sources can be superimposed and reproduced from a loudspeaker array in order to form multiple focused sound sources. By arranging the focused sources in arc shape, we produced the audio spotlight. A numerical simulation revealed that the sound volume difference between the center of an arc and at 1 m away from the center was approximately 10 dB. Moreover, because a flat frequency response was maintained at the center of the arc, the proposal is expected to be able to control optional sounds with minimal distortion.
Directivity control for regular polyhedron loudspeaker array based on weighted least-squares method using adjusted weight in spherical harmonics domain
Authors: Daikohara Makoto , Haneda Yoichi
Published: November 2016

We propose an adjusted weight least-squares method for directivity control of spherical loudspeaker arrays in the spherical harmonics domain. In previous work, we demonstrated that the sidelobes of the directivity pattern can be suppressed using the weighted least-squares method in the frequency domain. However, the gains of the calculated filter coefficients were very large at low frequencies. Consequently, to overcome this problem, we designed filter coefficients in the spherical harmonic domain. First, we set an ideal directivity pattern using a window function. Next, we obtain the filter based on the weighted least-squares method in the spherical harmonic domain with an initial weighting factor. Then, we update the weighting factor only on the side opposite that being faced based on the difference in sound pressure level between the ideal and the simulated radiation patterns. We then repeat this process until the difference level is satisfied by the condition of the update. The results of comparison of our proposed method with our previous method and the conventional least-squares method indicate that although the beam width in the look direction is wider than our previous method, our proposed method effectively prevents increasing filter coefficients by limiting order at low frequencies.
An interleave division multiple access receiver for multi-user underwater acoustic communication
Authors: Jia Ning , Huang JianChun , Xiao Dong
Published: November 2016

A downlink interleave division multiple access (IDMA) receiver, employing sparse channel estimation and interference canceller (IC), is proposed for multi-user underwater communications. To eliminate inter-symbol interference (ISI) and multiple access interference (MAI), an equalizer, a decoder, and an interference canceller are implemented in the receiver. The equalizer is used to eliminate ISI. The channel parameters used in the equalizer are estimated by a modified OMP sparse channel estimation algorithm. The performance of channel estimation is further improve ed using the decoder soft output information during the receiver iteration. MAI, reconstructed by the decoder output and channel parameters, can be eliminated in IC section of other users. The receiver’s performance is verified in shallow water acoustic channels during a sea-trail in the South China Sea. Three different ranges between the transmitter and the receiver, i.e., 4.5 km,6 km, and 7 km, were investigated with a maximum of four users at the data rate of 500 bps per user. The results demonstrated that the proposed IDMA receiver provides good performance with low bit error rate (BER). Furthermore, the receiver has been applied in a real-time underwater communication network.
Automatic selection of the number of poles for different gender and age groups in steady-state isolated vowels
Authors: Kathiresan Thayabaran , Maurer Dieter , Dellwo Volker
Published: November 2016

Formant frequency estimation using a linear prediction (LPC) algorithm is based on the assumption of age- and gender-specific number of poles. However, when visually crosschecking the calculated formant frequencies along with a spectrogram, investigators often change the parameter because of a lack of correspondence. The misprediction is mainly due to a high variation within the calculated formant tracks, or tracks not matching with spectral peaks, possibly combined with an unexpected low or high number of occurring formants (e.g., formant merging, spurious formants). To solve the problem of changing the number of filter poles, we propose a new method which addresses the first aspect of the constancy of formant tracks. For a given vowel sound, the first three formant frequencies for three different settings (number of poles = 10, 12, and 14 for a frequency range 0-5.5 kHz) are calculated. The standard deviation of the formant tracks is used to find a Euclidean distance for three settings separately. The algorithm chooses the setting that produces least variability (minimum Euclidean distance) in steady-state vowel nuclei. We tested the method on vowel sounds of standard German /i, y, e, ø, ɛ, a, o, u/ produced by 14 men, 14 women, and 8 children.
High accuracy resampling for acoustic signals using hermite interpolation with pseudo spectral method
Authors: Maruyama Hotaka , Okubo Kan , Tagawa Norio
Published: November 2016

Interpolation is an essential technique to obtain continuous data from discrete data within a known range of coordinates in many research areas. Especially, resampling acoustic signal is an important application. It is necessary to obtain the value between digitally recorded data using a signal interpolation technology. It is a fundamental method of digital processing operations. In recent years, a 192 kHz high-resolution system is often employed, so that the accurate interpolation method is required to obtain the high resolution signals from the signals measured by the conventional lower sampling rate. In signal resampling using the Hermite interpolation, an interpolated value can be expressed as the convolution form by signal values and their derivatives. By using highly accurate derivatives, accuracy of resampling can be also improved. In this study, we propose a new highly accurate acoustic signal interpolation method combining the Hermite interpolation with the pseudo-spectral method. Moreover, we also propose their efficient computational algorithm employing separation technique. As a result, our evaluation clarified that the proposed method achieved more accurate signal resampling compared to the conventional methods.
Utilization of optional instrument sounds for simultaneous measurement of room impulse responses by ensemble music
Authors: Miyauchi Yuki , Tatekura Yosuke
Published: November 2016

We describe the influence of the separation accuracy via semi-blind source separation (semi-BSS) upon the measurement accuracy of the room impulse responses. Tatekura et al. had proposed a simultaneous measurement method of the room impulse responses with ensemble music. In this method, the room impulse responses were measured by separating ensemble music into each instrument sound reproduced from each loudspeaker. However, the influence of the separation accuracy via semi-BSS upon the measurement accuracy of the room impulse responses has not been clarified. Therefore, we evaluated the measurement accuracy of the room impulse responses and the separation accuracy by using the different instrument sounds. The room impulse responses were measured between two loudspeakers and a control point with 11 kinds of musical instrument sounds. From the result of the measurement accuracy, the difference between the maximum value and the minimum value was 10 dB. However, from the result of the separation accuracy, most of value held equivalent measurement accuracy. Therefore, under these measurement conditions, this method is expected to be able to measure the room impulse responses by optional instrument sounds.
Effect of individualization of interaural time/level differences with non-individualized head-related transfer functions on sound localization
Authors: Watanabe Kanji , Nishiguchi Masayuki , Takane Shouichi , Abe Koji
Published: November 2016

Head-related transfer functions (HRTFs) are known to include comprehensive auditory cues for sound source positions and show large inter-subject variation. Therefore, individualization of HRTFs is important for highly accurate sound localization systems such as virtual auditory displays. In the present study, we assume that the interaural time deffierence (ITD) and the interaural level difference (ILD) can be estimated from the listener’s anthropometric parameters. The individualization of the HRTFs is achieved by replacing the ITDs and ILDs of the non-individualized HRTFs with the listener’s ones. In this report, the effect of the individualization was evaluated by listening experiment. The non-individual HRTFs were obtained by interpolating magnitude response of the listener’s own HRTF and the flat ones. The ratios of the interpolation corresponded to the degrees of individuality. Then, the ITDs and ILDs were added to individualize HRTFs. From the results, the effect of the degree of individuality was insignificant, but the front-back confusions were significantly different between HRTFs on ipsilateral side and contralateral side. The results suggested that the individualization of HRTFs with ITDs/ILDs might be influenced by the spectrum of non-individual HRTFs.
Multiple-input multiple-output underwater acoustic communications by using a quasi-orthogonal group space-time architecture
Authors: Zhang Chen , Ge FengXiang , Dai Lin , Zhu Huiling
Published: November 2016

A Quasi-orthogonal Group Space-Time (QoGST) architecture is presented in this paper for better diversity and multiplexing tradeoff gains in Multiple-Input Multiple-Output (MIMO) underwater acoustic (UWA) communications. Both QoGST and Group Layered Space-Time (GLST) are the combination of space-time block coding (STBC) and layered space-time coding. For GLST, the STBC is taken just in each group. For QoGST, however, all groups are encoded together via inter-group STBC, which can effectively suppress the interference between groups with the orthogonal STBC. At the receivers, the STBC decoding is performed and thus we have the higher diversity gains for the group detection. A statistical model of UWA channel which is presented by Milica Stojanovic and contains variations caused by small- and large-scale effects is considered. Simulation results show that the frame error rate (FER) of QoGST is much lower than that of GLST, which means the QoGST has the higher diversity gains. Furthermore, the lower bound diversity and multiplexing tradeoff of QoGST is coincides with that of GLST and the upper bound diversity and multiplexing tradeoff of QoGST is closer to the optimal values.
Acoustic property of sound production by fat greenling (Hexagrammos otakii) in spawning season
Authors: Matsubara Naoto , Munehara Hiroyuki , Takahashi Ryuzo , Akamatsu Tomonari , Yamato Kazuki , Matsuo Ikuo , Kimura Nobuo , Maekawa Kazuyoshi , Yasuma Hiroki
Published: November 2016

Fat greenling (Hexagrammos otakii) is one of the important demersal fishes in Japanese local fisheries. Male fishes come over to neritic zone in spawning season, and make the territory as the spawning bed. It was suggested that fat greenling produces specific sounds during the protection of territory.The objective of this study was to examine acoustic properties of male sound production in spawning season as the basic data for estimating habitat density and activity by the passive acoustic methods. Field recordings were conducted during spawning season between Sept. and Nov. in 2014 and 2015. In each experiments, a specialized recorder was set by a territory throughout the breeding process, including courtship, spawning, and egg care. We extracted the acoustic properties such as the frequency of sound production, pulse duration, pulse number, call duration, and the frequency of sound production from recording data. There were different patterns of sound properties and their occurrence frequencies between before and after spawning. It was suggested that fat greenling changes the frequency and property of sound production depending on the situation like courtship, spawning, and protecting eggs.
Geoacoustic inversion base on modeling ocean-bottom reflection wave
Authors: Lu Licheng , Ren Qunyan , Ma Li
Published: November 2016

Ocean-bottom parameters surveying experiment was conducted at two sites in Chinese South Sea. A vertical array of four elements was used to measure reflection waves from ocean-bottom with the explosive charges. The ocean-bottom reflection waves are processed by analyzing the arriving time to identify the sediment layers, and then, a geoacoustic model with several numbers of homogeneous fluid sediment layers overlying a homogenous substrate half space is constructed. Using the direct arriving wave, an approach that matches the measured and modeled ocean-bottom reflection wave is to invert the bottom velocity and density profile. A low velocity layer is obviously observed at one site and a complex seabed profile at another site is established. The modeled wave form is compared with the measured one and shows a relative agreement.
The highly exaggerated attributes of the pop vocal in sound recordings
Authors: Case Alexander U.
Published: November 2016

The voice in sound recordings must generally reign supreme over the rest of the multitrack arrangement. The loudspeaker mediates its interaction with the architecture. The entire upstream production chain anticipates the challenge. Recording space, microphone choice, and signal processing are carefully coordinated to maximize the audibility of multiple attributes the voice — intelligibility, emotion, musicality, and tonal quality. The highly manipulated approach to speech for sound recording can shed light on approaches taken in the built environment for the talker/listener interface.
Intelligibility and acoustic analysis of speech production in synthetic and natural reverberant and noisy environments: A case study of Parkinson’s disease speech
Authors: Skowronski Mark D.
Published: November 2016

Our understanding of the effects of noise and reverberation on speech production and intelligibility is enhanced by the study of speech from talkers with Parkinson’s disease (PD) due to the fact that PD speech spans a wide range of intelligibility in quiet and that talkers with PD also span a wide range of speech motor control for compensation. A previous study on the intelligibility of Parkinson’s disease (PD) speech in a synthetic reverberant and noisy environment showed that speech intelligibility suffered primarily due to noise although the effects of reverberation were also significant [Shrivastav, ASHA 2011]. A follow-up study in natural reverberant and noisy environments (allowing for talker compensation) found that the decrease in speech intelligibility as speaking conditions worsened was proportional to dysarthria severity [Kopf et al., ASHA 2013], and an acoustic analysis quantified the range of compensations made by talkers with PD [Shrivastav et al., ASA May 2014]. The current study modeled the intelligibility data from the synthetic environment study and applied the model to the data from the natural environment study to quantify the effects of talker compensation on intelligibility and to relate acoustic measures of speech to talker compensation.
The snapping shrimp conundrum: Spatial and temporal complexity of snapping sounds on coral reefs
Authors: Lillis Ashlee , Mooney T A.
Published: November 2016

Snapping shrimp are abundant crevice-dwelling crustaceans worldwide. The short-duration broadband “snap” generated by the collapse of a cavitation bubble upon the rapid closure of their specialized claw is among the loudest bioacoustic sound in the sea. Because these shrimp form large high density aggregations, their colonies create a pervasive crackling in many coastal environments, and variation in shrimp acoustic activity substantially alters ambient sound levels at a given location or time. Despite their fundamental contribution to the soundscape of coral reefs, and probable influence on sound-receptive organisms, relatively little is known about snapping shrimp sound production patterns, and the underlying behavioural ecology or environmental factors. Recent advances in recording capacity and efforts to sample habitat soundscapes at high spatiotemporal resolution have provided datasets that reveal complex dynamics in snapping shrimp sound production. Our analyses of soundscape data from coral reefs show that snap rates generally exhibit diurnal and crepuscular rhythms, but that these rhythms can vary over short spatial scales (e.g., opposite diurnal patterns between nearby reefs) and shift substantially over time (e.g., daytime versus nighttime dominance during different seasons). These patterns relate to abiotic variables such as temperature, light, and DO, as well as life history processes, but the nature of these relationships and underlying causal mechanisms are only beginning to be explored.
Time frequency analysis of the coconut rhinoceros beetle chirps
Authors: Allen John S. , Ramm Hans , Jenkins Daniel
Published: November 2016

The Coconut Rhinoceros Beetle attacks the coconut palm trees in the Pacific Region and its foraging has led to the devastion of the palm trees in Guam. The beetle is an invasive species on the island of Oahu, Hawaii, since its latent arrival in 2013. Stridulation sounds produced by the beetles have been reported with respect to mating and aggressive male behavior. Previous studies have proposed the mechanism for the stridulation and reported on some preliminary acoustic recording of the chirp for groups of beetles. However, the chrip characteristics wth respect to different behavior have not been examined extensively and also the time frequency analysis of the chirp sounds specifically or male and female beetles has been limited. In laboratory setting, the chirp characteristics are investigated with respect individual beetles in terms of pulse length and chrip duration. Time frequency analysis is used quantifiy the frequency modulation. An Empirical Mode Decompositon (EMD) provides a means of determing the instantaneous frequency and phase. Sounds of wing beats during the beetle's take off and flight are also investigated.
Evaluating underwater ambient noise levels across a changing Arctic environment
Authors: Guerra Melania , Stafford Kathleen M. , Andrew Rex K.
Published: November 2016

As a result of climate change, the Arctic underwater acoustic environment is undergoing an unprecedented transformation of its ambient noise sources, including an expanded wind fetch over open water and an intensification of maritime transportation lanes across Northern routes. This comparative study synthesizes multi-annual passive acoustic monitoring (PAM) data collected at various Alaskan Arctic environments (Bering Strait, Chukchi Plateau, Chukchi, and Beaufort Seas) in order to evaluate the statistics of ambient noise across the changing region. Mean levels at significant frequency ranges are presented, as well as percentile PSD levels in 1-Hz frequency bins. Remote sensing sea ice data is utilized to separate each annual dataset into 3 different regimes: open water, covered, and transition (when ice is forming or breaking up). During each, the dominant large-scale noise sources are characterized and the relationship between noise and local wind speed is evaluated. Through manual inspection, ship transits and seismic surveys have been extracted, allowing ambient level associations on the scale of hours or days. Consistently across all years, the Chukchi Plateau site, which is the most distant from shore, presents the lowest overall ambient noise levels (20-40 dB lower than other locations), potentially indicating a new Arctic ambient noise baseline.
Acoustic measurements of vertical velocity and temperature fluctuations of a hydrothermal plume with comparisons to large eddy simulations
Authors: Di Iorio Daniela , Lavelle J W. , Adams Ian
Published: November 2016

The acoustic scintillation method is used to study the hydrothermal plume of Dante within the Main Endeavour vent field (MEF) at the Endeavour segment of the Juan de Fuca Ridge. Forty days of vertical velocity and temperature fluctuations were obtained from the rising plume above the Dante edifice in an environment where the flow is dominated by strong (5cm/s) semi-diurnal tidal currents and a northerly mean residual current (3cm/s). These acoustic measurements provide a window on deep-sea hydrothermal plume dynamics in strong oscillatory cross flows. A large eddy simulation, parameterized with anisotropic mixing coefficients, taking into account ambient stratification and time-dependent background flows and calibrated by the acoustic measurements, yields insight into turbulent processes, entrainment, plume bending, rise height, and, inferentially, mound heat flux. The turbulent dissipation rates for kinetic energy (ε) and thermal variance (εθ) is approximated by computing the Reynolds averaged sub-grid scale turbulent production from shear and buoyancy (ε = P-B) and from temperature fluxes (εθ = Pθ), respectively, which are needed to compare to the acoustic derived turbulence levels. A new cabled observatory reciprocal acoustic scintillation system on the NEPTUNE observatory that will allow real time measurements of mean and turbulent flow of a hydrothermal plume will also be introduced.
Efficient dispersion analysis of guided waves in cortical bone
Authors: Laugier Pascal , Bochud Nicolas , Vallet Quentin , Cai Xiran , Grimal Quentin , Minonzio Jean-Gabriel
Published: November 2016

Guided wave propagation is at the heart of the axial transmission techniques designed to assess bone health status. The method involves matching observed and predicted dispersion characteristics of guided waves. The strength of the technique is that it can infer more than one bone property from the measured ultrasonic data, such as cortical thickness, stiffness, or porosity. The suitability of the model chosen for the inversion has recently been debated and the question has been raised whether the physical model must take the soft tissue coating influence into account as well as perhaps other factors such as bone curvature. We present in this talk a series of experiments conducted on bone-mimicking phantoms (plates or tubes) with or without soft tissue-mimicking coating showing evidence 1/ that the experimental guided wave branches in the range of 0.4-1.6 MHz mainly exhibit sensitivity to the influence of the solid subsystem (bone) and 2/ that a simple non absorbing transverse isotropic free plate model provides an appropriate inverse model in all investigated cases, i.e., coated or non-coated plates and tubes. Finally, we demonstrate effectiveness of the inversion procedure in characterizing cortical bone using ex vivo and in vivo data.
Ultrasonic backscatter difference measurements of cancellous bone: Relationships with microstructure and bone mineral density
Authors: Hoffmeister Brent K. , Spinolo P. L. , Huber Matthew T. , Moore Joshua T. , Viano Ann M. , Huang Jinsong
Published: November 2016

Background: Backscatter difference techniques are being developed to detect changes in bone caused by osteoporosis. Backscatter difference techniques compare the power in one portion of an ultrasonic backscatter signal to the power in a different portion of the same signal. Goal: Investigate how backscatter difference measurements depend on the density and microstructural characteristics of cancellous bone. Procedure: Ultrasonic backscatter signals were acquired from 30 specimens of bone using a 1 and 5 MHz broadband transducer. The normalized mean backscatter difference (nMBD) was determined by computing the power difference (in dB) between two gated portions of the backscatter signal and dividing by the center to center time separation between gates. Microstructural characteristics of the specimens and bone mineral density (BMD) were determined using high resolution x-ray micro-computed tomography. Results: nMBD demonstrated moderate to strong linear correlations with microstructure and BMD (0.50 ≤ |R| ≤ 0.83). The measured correlations did not depend strongly on transducer frequency. Conclusions: The backscatter difference parameter nMBD may be sensitive to changes in microstructure and density caused by osteoporosis. [Work supported by NIH/NIAMS R15AR066900.]
Fabrication of bone phantoms using 3D printers
Authors: Ohno Masahiro
Published: November 2016

Requests for making physical models of human body parts, or phantoms, are increasing in accordance with the improvement of medical instruments. Advance in 3D technologies such as 3DCAD and 3D printers has facilitated the fabrication of more precise phantoms. In this paper, we report on our trial to make phantoms of bones that can be used in developing ultrasonic methods of osteoporosis diagnosis. We did not aim to make a complete model that mimics some certain diseased bones, but rather aimed to develop models the parameters of which, such as trabecular thickness, pore size, and its orientation, can be set as freely as possible. Multi-sliced X-ray CT images of bovine bones, those of artificial polymer foam, and purely numerically generated images were used as raw data. These images were converted to 3D data using commercial volume data generation software together with some 3DCAD and intermediate software packages, and finally printed by 3D printers. The bone-volume/total-volume ratio (BV/TV) was controlled by altering the thresholding value in 3D data construction, as well as by air-blast-polishing printed models. Results of ultrasonic transmission experiments are also shown.
Erosion of soft tissue by focused ultrasound-induced streaming
Authors: Maxwell Adam D. , Sapozhnikov Oleg A. , Bailey Michael R. , Kreider Wayne , Khokhlova Tanya D. , Schade George R. , Khokhlova Vera A.
Published: November 2016

Mechanical erosion of soft tissues into subcellular debris has been demonstrated with pulsed high-intensity focused ultrasound, facilitated by either boiling or cavitation bubbles. In this work, we propose acoustic streaming as a primary cause of tissue erosion at a tissue-fluid interface. Bovine liver tissue and polyacrylamide gels were sonicated in a degassed water bath, with the focus positioned at the tissue/fluid interface. Pulses with duration between 1 to 104 μs and constant duty cycle of 0.5% were applied from a 1 MHz transducer generating focal pressures |p-| ≤17 MPa and p+≤90 MPa. Results showed a strongly nonlinear change in erosion with pulse duration, being greatest for pulse lengths between 50-500 μs. For longer pulses (>1 ms), high-speed videos showed streaming velocities >10 m/s. Moreover, lesions >1cm in depth were produced in tissue phantoms even with a single pulse and tissue disruption was evident where no bubbles were observed at the tissue-fluid interface. Enhancement of erosion was observed with the presence of bubbles not directly adjacent to tissue but along the beam path, possibly due to bubble-enhanced streaming. [Work supported by NIH R01 EB007643, T32 DK007779, K01 DK104854, P01 DK043881, and NSBRI through NASA NCC 9-58.]
A multimodal evaluation of boiling histotripsy lesion properties in ex vivo bovine liver
Authors: Wang Yak-Nam , Khokhlova Tanya D. , Maxwell Adam D. , Kreider Wayne , Partanen Ari , Farr Navid , Schade George R. , Chernikov Valeriy P. , Buravkov Sergey V. , Bailey Michael R. , Khokhlova Vera A.
Published: November 2016

New types of high intensity focused ultrasound (HIFU) therapy aiming at mechanical homogenization of tissue has shown great promise, namely, cavitation-cloud histotripsy and boiling histotripsy (BH). BH uses millisecond-long bursts of HIFU waves containing shocks to repeatedly induce boiling at the focus; the interaction of incident HIFU waves with vapor bubbles homogenizes tissue. In this study, degassed ex vivo bovine liver samples were sonicated using a 256-element 1.2 MHz array of a clinical MR-HIFU system. The BH lesions were produced using 10-ms long pulses with 80 MPa shocks in situ and pulse repetition frequencies (PRFs) of 1-10 Hz to cover a range of effects from pure mechanical homogenization to thermal ablation. Individual lesions were generated for the multimodal analysis of the lesion including ultrastructure (electron microscopy), molecular (biochemistry), and microstructure (histological) methods. The extent of homogenization and thermal denaturation was evaluated for each lesion. The results of this work showed that the degree of mechanical tissue disruption and the amount of heat generated in large BH lesions can be tailored to result in a range of desired tissue effects dependent on the target clinical application. [Work supported by NIH EB007643, RFBR 16-02-00653, K01 EB015745, and NSBRI through NASA NCC 9-58.]
Designing a multi-element array transducer for abdominal boiling histotripsy applications
Authors: Rosnitskiy Pavel , Yuldashev Petr , Maxwell Adam , Kreider Wayne , Bailey Michael , Sapozhnikov Oleg , Khokhlova Vera
Published: November 2016

The boiling histotripsy (BH) method to mechanically fractionate tissue using high intensity focused ultrasound relies on the presence of high amplitude shocks. Recently, a method of determining single-element transducer parameters to achieve desired shock amplitudes at the focus was developed. It was shown that the transducer F-number is the main parameter that determines the focal pressure level at which fully developed shocks form. Here, a 256-element HIFU array transducer of 1.5 МHz frequency was designed for abdominal BH applications using the proposed method. An opening was included at the center of the transducer to fit an ultrasound imaging probe and a compact 16-arm spiral layout of uniformly sized elements was chosen for maximizing the transducer power output. The F-number of the array and the diameter of its elements were determined to satisfy technical limitations on the intensity level at the array elements as well as the required shock amplitudes of 90-100 MPa at the focus assuming 9 dB attenuation losses in tissue. For creating volumetric lesions, the region of safe and efficient steering of the array focus was evaluated using the T-Array software package (www.limu.msu.ru). [This work was supported by RSF 14-12-00974 and NIH R01 EB7643.]
Histotripsy pulse-reflection for 3D image forming and bubble cloud localization in transcranial applications
Authors: Sukovich Jonathan R. , Xu Zhen , Hall Timothy L. , Macoskey Jonathan J. , Cain Charles A.
Published: November 2016

Here, we present results from experiments using histotripsy pulses scattered off the surface of the skull, as well as bubble clouds generated within, to reconstruct 3D images of the exterior skull surface and localize bubbles within. These capabilities have the potential to provide image coregistration and real-time ultrasound monitoring for transcranial histotripsy treatment, without the need for MRI guidance. Histotripsy pulses were delivered to an ex vivo human skullcap mounted centrally within a 500 kHz, 256-element histotripsy transducer with transmit-receive capable elements. Straight-line ray tracing approximations based on the times-of-flight of the emitted pulses and the known geometry of the array were used to calculate points on the skull surface and to localize bubble clouds generated within. Using these methods, we were able to accurately locate and orient the skull within the array and generate a 3D map of its surface for coregistration with an a priori 3D scan. The points calculated based on the pulse-reflection from the skull were found to be within 1.25 mm of the surface measured in the a priori 3D scan. Using these signals, the calculated centroid of the generated bubble clouds was likewise found to be within 500 um of the measured focal point of the array through the skull.
Monitoring and guidance of histotripsy using ultrafast imaging
Authors: Arnal Bastien , Lee Wei-Ning , Pernot Mathieu , Tanter Mickael
Published: November 2016

To use histotripsy safely, it is required to visualize the cavitation clouds and the lesion formation in real-time. Conventional ultrasound imaging (USI) is a good candidate for the real-time monitoring of the procedures. However, bubble clouds are not always clearly visible in vivo using USI because of flows, motion or high echogenicity of the target region. Ultrafast imaging, based on plane wave or diverging waves sonications, is able to record a larger amount of data, providing broad information about how signals originating from different sources vary in time. Here, we apply a spatiotemporal singular value decomposition of ultrafast acquisitions that enables the discrimination of cavitation bubbles from moving tissue in vivo. An automation to determine the filtering parameters will be introduced. Moreover, USI depicts the histotripsy lesion only at an advanced stage and can be hindered by the presence of dissolving gas in the tissue. As the tissue microstructure is greatly affected by the treatment, a high stiffness contrast is observed. We will show that quantitative stiffness evaluation allows measuring tissue damage from the beginning of the treatment with a 2 to 6-fold contrast increase compared to USI.
The effects of heat and mass transfer on free oscillations of a bubble in a viscoelastic, tissue-like medium
Authors: Johnsen Eric , Barajas Carlos
Published: November 2016

Free oscillations of a bubble in soft tissue is of relevance to a variety of diagnostic and therapeutic ultrasound applications. Heat and mass transfer effects have been explored in the context of bubble oscillations in water; however, the extent to which they influence bubble oscillations in soft materials is presently unknown. Our objective is to use numerical modeling to predict bubble oscillations in viscoelastic, tissue-like media, while accounting for heat and mass transfer. We numerically solve the Keller-Miksis equation to compute the Rayleigh collapse of a spherical bubble in a Kelvin-Voigt viscoelastic medium with finite-strain elasticity. The energy equation is solved inside and outside the bubble, and a mass conservation equation is solved for the vapor inside the bubble; equilibrium phase change is assumed. Using linear, small-amplitude perturbation theory, we investigate the bubble response. We show how the damping and oscillatory behavior depends on the eigenvalues of the full system; in particular, the time constant does not follow a monotonic relationship with respect to shear modulus. We also identify regimes in which solving the fully partial differential equations for energy and vapor concentration is not necessary. Finally, we interpret our results in the context of ultrasound applications.
Modeling tissue response to a cavitation bubble in histotripsy
Authors: Mancia Lauren , Vlaisavljevich Eli , Xu Zhen , Johnsen Eric
Published: November 2016

Histotripsy is a noninvasive focused ultrasound procedure that uses cavitation bubbles generated by high-amplitude ultrasound pulses to mechanically homogenize soft tissue. Experimental studies of histotripsy-induced cavitation in tissue phantoms and animal models have shown that tissue mechanical properties such as viscosity and elasticity affect cavitation threshold and bubble behavior. At present, however, the mechanisms responsible for tissue damage observed in histotripsy and other cavitation-inducing ultrasound treatments remain difficult to quantify. In this study, we simulated the dynamics of a single, spherical bubble in a Kelvin-Voigt-based viscoelastic solid, with nonlinear elasticity to better represent nanometer to micron-scale bubble growth. We applied the numerical model to calculate stress, strain, and strain rate distributions produced by a cavitation bubble exposed to forcing representative of a tensile histotripsy cycle. We found that stress and strain in excess of the ultimate tensile strength and fractional strain of most soft tissues occur at the bubble wall and decrease by at least two orders of magnitude within 50 microns from the bubble. Tissue mechanical properties were found to affect the magnitudes of stress and strain developed at different distances from the bubble. We will relate these results to experimentally observed correlates of tissue damage.
Optical sensing of sound fields: Non-contact, quantitative, and single-shot imaging of sound using high-speed polarization camera
Authors: Ishikawa Kenji , Yatabe Kohei , Ikeda Yusuke , Oikawa Yasuhiro , Onuma Takashi , Niwa Hayato , Yoshii Minoru
Published: November 2016

Imaging of a sound field aids understanding of the actual behavior of the field. That is useful for obtaining acoustical spatial characteristics of transducers, materials and noise sources. For high spatial resolution imaging, optical measurement methods have been used, thanks to its contactless nature. This paper presents sound field imaging method based on parallel phase-shifting interferometry, which enables to acquire an instantaneous two-dimensional phase distribution of light. Information of sound field is calculated from the phase of light based on the acousto-optic theory. The system consists of a polarization interferometer and high-speed polarization camera, whose measurement points of a single image are 512 × 512 and spatial resolution is about 0.2 mm × 0.2 mm. Therefore, the system can image a sound field with much higher spatial resolution compared with conventional imaging methods. The maximum framerate, which is corresponding to the sampling frequency, is 1.55 M frames per second. This paper contains the principle of optical measurement of sound, the description of the system, and several experimental results including imaging of a transducer-generated sound field and propagation and reflection of a sound wave.
Numerical investigation on transmission loss of sound above sea surface
Authors: Taylor Robert , Turo Diego , Ryan Teresa , Vignola Joseph
Published: November 2016

Determination of the transmission loss of sound travelling over the ocean with various sea states involves a number of variables. One method to approximate the random roughness of the surface is to use the variance spectrum model as proposed by Pierson and Moskowitz. A numerical solution of the wave equation is presented for a small elevation angle over the sea surface at different sea states. This new model has the capability to include both the thermal gradient and wind profile above the sea. The solutions are derived with an implementation of the Crank-Nicolson Parabolic Equation, and the ocean wave roughness profile is introduced into the numerical model by the Generalized Terrain Parabolic Equation method. These results are used to investigate the effect of the sea roughness on the sound transmission loss for different sea states.
Adaptive statistical learning models for long-range sound propagation
Authors: Hart Carl R. , Wilson D. K. , Pettit Chris L. , Nykaza Edward T.
Published: November 2016

Uncertainties in source characteristics, meteorological conditions, and topographic variations present formidable challenges for accurately predicting long-range outdoor sound propagation. Numerical propagation models inherently assume perfect knowledge of these uncertain variables and are fixed in a modeling sense. In contrast, statistical learning models can incorporate new observations to update the underlying prediction model. Past work has shown that statistical learning models trained on synthetic data for predicting long-range sound propagation have, at best, an overall root-mean-square error (RMSE) of about 5 dB. This limit appears to be imposed by modeled atmospheric turbulence. It is hypothesized that this prediction limit may be lowered as observational data are incorporated into trained statistical learning models. Furthermore, data are assimilated by a Kalman filtering process for the purpose of updating knowledge of the atmospheric and source characteristics. Within the prediction phase three different statistical learning models are compared: an ensemble neural network, a cluster-weighted model, and a random forest regression model. The efficacy of data assimilation is evaluated with respect to each statistical learning model.
Songle Widget: A web-based development framework for making animation and physical devices synchronized with music
Authors: Goto Masataka , Yoshii Kazuyoshi , Nakano Tomoyasu
Published: November 2016

This paper describes a web-based multimedia development framework, Songle Widget (http://widget.songle.jp), that makes it possible to control computer-graphic animation and physical devices such as lighting devices and robots in synchronization with music publicly available on the web. Development of applications featuring rigid synchronization with music playback on the web was difficult because audio signals of the playback are not accessible on a web browser and manual annotation is time-consuming. To overcome such difficulties, Songle Widget makes it easy to develop web-based applications with rigid music synchronization by leveraging music-understanding technologies based on signal processing. Songle Widget is implemented by using our public web service called Songle (http://songle.jp) that automatically analyzes songs on the web and annotates four important types of musical elements (music structure, hierarchical beat structure, melody line, and chords). More than 1,000,000 songs on music- or video-sharing services have been analyzed by Songle and can readily be used by music-synchronized applications. Since errors are inevitable when elements are annotated automatically, Songle Widget takes advantage of a Songle's crowdsourcing interface that enables users to correct errors. This is effective when applications require error-free annotation. We made Songle Widget open to the public, and its capabilities and usefulness have been demonstrated.
Rethinking audio production tools
Authors: Pardo Bryan
Published: November 2016

Potential users of audio production software, such as equalizers and reverberators, may be discouraged by the complexity of the interface and a lack of clear affordances in typical interfaces. We seek to simplify interfaces for audio production (e.g., mastering a music album with ProTools), audio tools (e.g., equalizers), and related consumer devices (e.g., hearing aids). Our approach is to center the interaction around user-provided examples, an evaluative paradigm (“I like this sound better than that sound”) and descriptive language (e.g., “Make the violin sound ‘warmer.’”). To build interfaces that use descriptive language, a system must be able to tell whether the stated goal is appropriate for the selected tool (e.g. making the violin “warmer” with a panning tool does not make sense). If the goal is appropriate for the tool, it must know what actions need to be taken (e.g., add some reverberation). Further, the tool should not impose a vocabulary on users, but rather understand the vocabulary users prefer. In this talk, Prof. Pardo describes recent work in evaluative interfaces, crowdsourcing a vocabulary for language-based production tools, and language-based interfaces for production tools.
Statistical models for the indirect acquisition of violin bowing controls from audio analysis
Authors: Perez-Carrillo Alfonso
Published: November 2016

Acoustical studies of sound production in bowed string instruments show that there is a direct relationship between bowing controls and the sound produced. During note sustains the three major bowing parameters that determine the characteristics of the sound are the bowing force (bforce), the bowing distance to the bridge (bbd) and the bowing velocity (bvel). During note attacks the third parameter is acceleration (bacc) rather than velocity. We are interested in understanding this correspondence between bowing controls and sound but in the opposite direction, i.e., mapping sound features extracted from an audio recording to the original bowing controls used. This inverse process is usually called indirect acquisition of gestures and is of great interest in different fields ranging from acoustics and sound synthesis to motor learning or augmented performances. Indirect acquisition is based on the processing of the audio signal and it is usually informed on acoustical or physical properties of the sound or sound production mechanism. In this paper, we present indirect acquisition methods of violin controls from an audio signal based on training of statistical models with a database of multimodal data (control and sound) from violin performances.