bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient modeling of sound transmission through finite-sized thick and layered wall and floor systems
Authors: Decraene Carolina , Dijckmans Arne , Reynders Edwin
Published: June 2017

Built-up wall and floor systems such as roof panels, floors with floating screeds, etc., have found widespread application in building construction. Achieving sufficient sound insulation with these systems is challenging because of their relatively low weight and complex vibro-acoustic behavior. A fast and sufficiently accurate acoustic design tool is needed. The semi-analytical transfer matrix method is able to efficiently compute the response of a thick or multilayered structure in the frequency-wavenumber domain but has important limitations. First, the system is assumed to be of infinite extent. At lower frequencies however, neglecting the modal behavior of the wall can lead to large prediction errors. Second, integration over all possible incident plane waves is necessary to obtain the diffuse transmission loss, resulting in a high computation time. The transfer matrix approach is therefore extended in two ways. The modal behavior of rectangular walls and floors with simply supported boundary conditions is approximately accounted for. Using the diffuse reciprocity relationship, a hybrid modal transfer matrix-statistical energy analysis method is then developed such that integration of plane-wave transmission over all angles of incidence is no longer necessary, largely decreasing the computational effort. The model is validated against alternative numerical prediction models and experimental data.
Methodology for measuring and predicting heavy-weight impact noise transmission
Authors: Silva Richard , Dong David W. , LoVerde John
Published: June 2017

Noise and vibration from activity in fitness facilities, in particular dropping of weights, is a common source of disturbance and complaint in the United States of America (USA). Products have been developed to mitigate such impact, but quantitative and comparable data of their effectiveness is lacking. In the United States, there is no standardized method for evaluating the reduction in noise or vibration provided by these products, and also no method for predicting noise and vibration levels in potentially affected spaces. The authors’ previous research (Internoise 2015, Noise-Con 2016) developed a preliminary test method to evaluate athletic tile flooring with heavy weight drops. The method is based on the reduction in floor vibration when the products are inserted. The method is analogous to the delta-Ln term in the EN12354 calculation method, except applying to heavy weight sources, and can therefore be used to predict the resulting sound levels in receiving spaces. This paper reports additional measurements on different structural systems to validate the applicability of the method. Various flooring products are compared, and the accuracy and repeatability of the measurement method is evaluated.
The effects of the element damping in sound insulation predictions following EN12354
Authors: Gerretsen Eddy
Published: June 2017

In the prediction of the sound insulation between dwellings in accordance with EN 12354 the damping of the elements in the actual construction is an important aspect. It should be taken into account through the structural reverberation time or, in case of well-damped and generally light weight elements, it is included in the input parameters. As a simplified approach though, the effect of the damping can be neglected. In this respect, several questions are relevant. In what situation should the structural reverberation time in the actual construction be taken into account or when is an element enough damped to make the connections to other elements irrelevant. What relations exists between the junction parameters for damped and reverberant elements. And what errors do we make in neglecting the damping in the actual construction for the elements, for the junctions or for both. Looking deeper into the equations and relations between them some global answers can be given to those questions.
On the measurement of the radiation efficiency for the estimate of the resonant sound reduction index
Authors: Mahn Jeffrey , Höller Christoph
Published: June 2017

The estimate of the resonant sound reduction index has received attention over the years as the prediction method described in the standard, ISO 15712 has been applied to lightweight building constructions. A method of estimating the resonant sound reduction index involves the measurement of the total and the resonant radiation efficiencies of the building elements involved in the first order flanking paths. The radiation efficiencies of different lightweight wall constructions were evaluated as part of a study conducted at the National Research Council Canada are presented. The study focused on the measurement of the radiation efficiencies with the aim of developing guidelines for the measurements. Predicted values of the flanking transmission loss for each flanking path are compared to data which was measured in the National Research Council's eight room flanking facility.
Dilemmas in the assessment of the insulating properties of double massive partition according to EN 12354-1
Authors: Sumarac Pavlovic Dragana , Bjelic Miloš , Dinic Milos , Mijic Miomir , Bezbradica Vlada
Published: June 2017

The introduced requirements for thermal insulation between dwellings, as well as some practical reasons, initiated greater use of double walls in building design practice. The standard EN 12354 -1 did not defined a procedures for calculation of the apparent sound reduction index for such constructions. The paper suggests a possible approach for calculation of apparent sound reduction index based on the calculation methodology for the single partition defined by the standard. Some theoretical analyses of the sound energy transmission through direct and flanking paths in a case of double massive partition were presented. Verification of the proposed approach were done by laboratory measurement and by FEM numerical simulation. The analysis included a number of commonly used constructions and types of their junctions.
The prediction of the flanking transmission in constructions of hollow concrete block masonry walls connected to precast prestressed concrete hollow core floors
Authors: Mahn Jeffrey , Höller Christoph
Published: June 2017

A common construction technique for multi-story buildings is to build walls of hollow concrete block masonry which are rigidly connected to floors of precast prestressed concrete hollow core slabs. The airborne flanking transmission for buildings of this construction must be determined to predict the apparent sound transmission class to meet the requirements of the National Building Code of Canada. Ideally, this would be done using the prediction method and the vibration reduction index values found in the standard, ISO 15712. However, prior studies conducted at the National Research Council Canada have shown that the hollow core slabs are neither homogeneous nor isotropic which are the requirements for predicting the values of the vibration reduction index (Kij) according to Annex E of the standard ISO 15712. To determine if the theoretical values of the vibration reduction index could nonetheless be applied in practice, an experimental investigation was performed on full scale junctions between concrete block masonry walls and precast concrete hollow core floors built and tested in full compliance with the standard ISO 10848. The investigation found that conservative vibration reduction index values could be predicted using Annex E of ISO 15712.
Prediction of vibration reduction index for junctions made of cross laminated timber elements
Authors: Poblet-Puig Jordi , Guigou-Carter Catherine
Published: June 2017

The new revision of standard EN 12354-1 will provide some prediction formulas for estimating the vibration reduction index (Kij) of junctions made of cross laminated timber (CLT) elements. These are based on laboratory and in situ measurements. At the same time, new Kij prediction formulas for heavyweight junctions have also been added to this revised standard, in order to include large amount of data generated by means of parametric numerical analysis. The goal of this research is to study if the same philosophy based on numerical models used for the heavyweight junctions can be extended to CLT elements junctions. This step is not direct because the modeling of CLT structures implies a list of non-trivial aspects to take into account: (1) the details of the junction construction (i.e., direction and type of screws, presence of steel angles and plates); (2) the orthotropy on the mechanical properties of CLT panels; and (3) the different range of material properties and how damping must be considered in the numerical model. The contribution presents the advances made in this direction: comparison with available experimental data, analysis of specific aspects of CLT junctions, comparison with the standard formulation, and extension to different junction types.
Measurement data for the prediction of the flanking transmission in lightweight building constructions
Authors: Mahn Jeffrey , Höller Christoph
Published: June 2017

The ISO 15712 series of standards describe a method of predicting the flanking transmission in homogeneous isotropic building constructions. Since the method was first published in 1979, there has been great interest in applying the prediction method to lightweight constructions which are neither isotropic nor homogeneous. The prediction method becomes more complicated for lightweight constructions because the resonant sound reduction indices of the elements must be estimated from measurement data including the sound reduction indices and the resonant and total radiation efficiencies. However, there is the question of which sound reduction index and radiation efficiencies should be used. Should they be for the whole wall or a single panel? Results from a study conducted at the National Research Council Canada are presented. Predicted values of the flanking transmission loss for each flanking path are compared to data which was measured in the National Research Council's eight room flanking facility.
Noisy voice or voice in noise: Evaluation of cognitive load on the speaker, work in progress
Authors: Verduyckt Ingrid A. , Botteldooren Dick , Vandevelde Annelies , Bockstael Annelies
Published: June 2017

We are comparing the cognitive load induced by various types of noise in the processing of information from speech. We examine if there is a difference in cognitive load between external noise sources (background noise) and internal noise sources (dysphonic voice). Our hypothesis is that noisy voices could be more cognitively demanding than background noise because they are more similar to the target signal spatially and temporally and the perceived link with the target signal is stronger. 60 normal hearing subjects (18-30 years) listen to texts in ten different conditions: (1) Healthy voice in multitalker babble noise, (2-4) Three types of dysphonic voices in background noise, (5-7) Three dysphonic voices in silence, (8) Healthy voice in silence, (9) Healthy voice with omnidirectional noise equivalent to dysphonic noise, (10) Healthy voice with dysphonic noise from same direction. We evaluate cognitive load in 4 ways: (1) during the listening phase by subjects’ performance on a secondary graphic task, (2) after the listening phase by subjects’ answers to a multi choice questionnaire and (3) by a free recall of the text, (4) by subjects’ grading of their listening effort. Methodological considerations will be discussed and preliminary results will be presented.
Communication problems among teachers and noise conditions… hearing difficulties also matters!
Authors: Cantor Cutiva Lady Catherine , Bottalico Pasquale , Burdorf Alex , Hunter Eric J.
Published: June 2017

Previous studies on the influence of noise in the classroom on the hearing function of teachers have primarily focused either on physical education teachers or music teachers. However, the influence of classroom noise on hearing difficulties among teachers is largely unknown. The aim of this study was to assess the association between classroom noise levels and self-reported classroom acoustics with self-reported hearing impairments among teachers. In 12 public schools in Bogotá, we conducted a cross-sectional study among 621 Colombian teachers at 377 workplaces. Teachers filled out a questionnaire on individual and self-perceived noise conditions inside the classroom along with perception of their hearing impairments. Logistic regression analysis was used to determine associations between background noise levels and self-reported hearing impairment. High noise levels in the surroundings of schools (Odds ratio [OR] 2.15; 95% confidence interval [CI] 1.25-3.68) was associated with self-reported hearing impairments, but self-reported classroom noise showed no association (Odds ratio [OR] 1.34; 95% confidence interval [CI] 0.91-1.99). This study indicates that noise in schools may play a role in self-reported hearing impairments among teachers.
Field survey on the sound environment of childcare facilities in Japan: Analysis of sound generation accompanied by children's activities
Authors: Noguchi Saki , Ueno Kanako
Published: June 2017

Today's childcare facilities in Japan have problems in their sound environments such as bustling noises, and it is pointed out as a result of lack of sound absorption and awareness of the sound environment of people in the field. On the other hand, the sound environment is actually different depending on age and type of activity, but detailed examination has not been done. In this presentation, for the purpose of setting up an acoustic environment according to the development of children and the aim of childcare activities, we report the results of surveying sound environments focusing on group size, age, activity space, and activity contents. We investigated the sound environment and childcare activities in five childcare facilities with different facility type, scale, and operation type. It was observed that children's sounds changed with the development of language and behaviors. The characteristics of sound environment differ depending on actual activity situation and spatial property, and special acoustic contrivance was necessary in the free play scene because different activity sounds were mixed there.
Trial in a nursery facility for improving the sound environment
Authors: Ueno Kanako , Miyatsuka Ken
Published: June 2017

In Japan, most nursery facilities have been built without considering the acoustic requirements; thus, the rooms tend to be reverberant and very noisy from the daily activities of children. The poor sound environment could be harmful not only as a living environment for the children but also as a working environment for the nursery staff. This presentation reports on a case study of a nursery that worked on the reduction of its high sound level. First, the architectural features of the nursery room and the status of the sound environment, which was reported by the nurses’ claims and measured to be approximately 80 dB or higher during lunch time, was investigated. Second, to improve the noisy environment, two tasks were carried out. One was the installation of absorbing materials onto the walls and ceilings, which shortened the reverberation time by half. The other was the introduction of management efforts aiming for children to lower the loudness of their voices. These were performed with a demonstration of proper voice levels with animals of different scales and the generation of a music box sound during lunch. The effects of these trials were physically analyzed by sound recordings and subjectively evaluated by nurses.
Experimental measurements of word intelligibility of pre-school children under acoustic interferences of reverberation and background noise
Authors: Kawai Keiji , Harada Kazunori
Published: June 2017

Child day-care rooms require optimum acoustic condition as children from 0 to 5 years old are supposed to be vulnerable group against interferences with verbal communication by background noise and excessive reverberation. However such interferences on the children seem not to have been examined in the field of architectural acoustics. Thus on-site experiments were carried out to measure word intelligibility of children from 3 to 5 years old. The procedure was like a true or false game. Each of the test words was mixed with two or three levels of pink noise and convolved with the room impulse responses with different reverberation times. The words were presented to the children and control groups (elementary school pupils and college students) by a loudspeaker in a daycare room. They were asked to judge whether the word was food or not, and to raise their hands holding yes or no signs. The experiment was repeated three times in different daycare centers with revisions of the condition settings. As the results, the correct answer ratios of pre-school children was lower than that of control groups, in general, and particularly, the ratio of 3-years-old children was much lower than that of other groups. Also under low S/N ratio conditions the ratios of all the groups decreased along with long reverberation.
Voice production effects due to extreme reverberation times in real rooms
Authors: Rollins Michael , Leishman Timothy W. , Berardi Mark , Hunter Eric J.
Published: June 2017

Public school teachers have a heightened risk of voice problems. There are many potential causes of this increased vocal risk, including poor room acoustics (e.g., excessively high or low reverberation times). With increased understanding, rooms could be better designed to maintain communication transfer (intelligibility), while mitigating unhealthy vocal effort and, by extension, voice problems. The present study quantified the influence of a wide range of reverberation times (RT20) on vocal production parameters. Thirty-two participants were recorded completing a battery of speech tasks in eight widely ranging conditions within a reverberation chamber. Changes in RT20 had highly correlated effects on several vocal parameters, including smoothed cepstral peak prominence, acoustic vocal quality index (AVQI), and pitch strength. As RT20 increased, vocal parameters tended toward values commonly associated with dysphonic phonation. Additionally, results were gender dependent, with females tending to produce voice with higher vocal effort than males. These findings begin to objectify the effects of room acoustics on vocal accommodations and provide grounds for developing future talker-oriented room acoustical standards.
Self-reported voice problems and contributing factors in a Francophone population of professional and student teachers and nurses
Authors: Verduyckt Ingrid A. , Tordeur Amandine , Watteau Laure-Anne
Published: June 2017

Context: We explored the relation between work related factors, health practices, personality traits and stress-coping strategies and self-reported voice problems in a population of 354 student teachers (ST), 344 professional teachers (PT), 147 student nurses (SN) and 104 professional nurses (PN). Method: An online survey was conducted. Beside an anamnestic questionnaire to collect data about voice problems, work environment, health practices the VHI-10 was used to quantify voice symptoms, the Big Five-10 to explore personality traits, and the WCC-27 to explore stress coping strategies. Results: The prevalence of self-reported voice problems was significantly higher in ST as compared to SN (23% vs 14%, p = 0.025) and in PT versus PN (24% vs 12%, p = 0.08). VHI scores were significantly higher for subjects self-reporting a voice problem and significantly higher in the professional than the student groups, with PT with self-reported voice problems having the highest scores (Mean = 22.34 SD = 0.635) p<0.001. An ANOVA shows that 55% of the variance of the VHI scores is explained by the status of the subject (ST/PT/SN/PN), (F(3,945) = 382.156, p<0.001). A linear regression shows that 43% of the variance of the VHI scores was explained by Amount of private voice use, Conscientiousness, Extraversion and Emotion centered coping scores (F(4,830) = 159.201,p<0.001).
Sonar processing by the spectrogram correlation and transformation model of biosonar
Authors: Haro Stephanie , Simmons James A. , Gaudette Jason E.
Published: June 2017

Echolocating big brown bats emit frequency-modulated (FM) biosonar sounds and perceive target range from echo delays through spectrogram correlation (SC) and target shape from interference nulls in echo spectra through spectrogram transformation (ST). Combined, the SCAT model is a computationally unified auditory description of biosonar as a real-time process. We developed a Matlab implementation of SCAT and tested it with a succession of simulated bat-like FM signals (chirps), each followed by one or more FM echoes that have realistic delay and spectral characteristics. The model simulates neural response latencies in frequency-tuned delay-lines that use coincidence detections for target ranging by SC. For ST, a novel, deconvolution-like network transforms echo spectra into images of the target’s glints by detecting coincidences between spikes that represent spectral nulls in parallel channels tuned to null frequencies. Experiments show that dolphins likely separate ST into two operations—MaPS for short glint separations (macro power spectral features, <80 µs) and MiPS for longer separations (micro power spectral features, >80 µs). The ST deconvolution network models MiPS. The highly distributed character of the model favors real-time operation, an important goal for bioinspired sonar development. [Work supported by ONR.]
Scattering statistics of glacially quarried rock outcrops: Bayesian inversions for mixture model parameters
Authors: Olson Derek R. , Lyons Anthony P.
Published: June 2017

Knowledge of the probability distribution of the scattered amplitude return from the seafloor in reverberation measurements and seafloor sonar images is a prerequisite to designing effective target detection systems and predicting their performance. Previous measurements have revealed that the distribution is often heavier tailed than the Rayleigh distribution, and may be modeled by the K, Weibull, and log-normal distributions, among others. Recent measurements of the scattering statistics from rock seafloors resulted in a bimodal distribution, which is poorly modeled by many commonly used distributions. The rock surfaces were formed from glacial quarrying and exhibit a stepped structure. The observed distribution is hypothesized to result from a mixture, where the scattered field from vertically oriented facets is modeled as a K distribution, and the scattered field due to the horizontally oriented facets is modeled as a Rayleigh distribution. If this hypothesis is true, then roughness parameters may be estimated from scattering data. A Bayesian technique for estimating the distribution of mixture parameters from the probability distribution of the scattered field is presented. This technique, while computationally expensive, reveals the relationship between the mixture model parameters, and can reveal any degeneracies that could lead to problems during inversions.
Mode coupling and redistribution of the sound intensity over depth at downslope propagation, in the area of thermocline's contact with bottom
Authors: Katsnelson Boris , Lunkov Andrey
Published: June 2017

Downslope propagation of the sound signal is studied in a coastal wedge when the temperature profile reveals the strong thermocline. Sound source is placed above the thermocline near the point of thermocline contact with bottom (TC point). Depth dependence of the sound intensity is considered far enough from the coastal line as a function of distance to the source. It is shown that for some position of the source between TC point and the coast, remarkable redistribution of the sound intensity over water depth takes place (sound field is stressed to the bottom). Numerical simulations of this phenomenon are carried out using adiabatic and coupled normal mode decomposition for bottoms with different sound speeds. Results of modeling are compared with the data of experiment in Lake Kinneret, where coastal slope is characterized by variation of depth from the coast to the 40 m at the distance about 8 km and sound speed profile with the thermocline at 20 m depth. Chirp signals with the center frequency 600 Hz were received by the vertical line array (VLA). Vertical distribution of the sound intensity along VLA was measured. Variability in accordance with theoretical model is demonstrated. [Work was supported by ISF.]
Acoustic mode based internal tide tomography from the PhilSea 2009 experiment
Authors: Chandrayadula Tarun K. , Colosi John A. , Worcester Peter F. , Dzieciuch Matthew
Published: June 2017

The Philippine Sea 2009 experiment transmitted low frequency broadband sound pulses to a mode resolving array located at 185 km. The entire experiment was conducted over a period of one month, during which, most of the transmissions took place every 5 min, and the rest every 3 h. This talk estimates the travel times of the mode pulses and inverts them for the internal tide induced sound speed variability across the propagation path. A first order perturbation theory approach models mode travel times as range-averaged function of the sound speeds. Depending on the propagation distance, the contributions from some internal tide wavelengths are enhanced while others suppressed in the mode travel times. The talk shows the month-long time-series of the mode peak arrival times and estimates a spectrum for the observations. The presentation then derives an expression to relate the spectral components of the mode arrival times in terms of the internal tide spatial wavenumbers. The magnitude of the arrival time spectral components at the tide frequencies are used to invert for the respective internal tides across the propagation path. The tomographic inverse for the internal tides are compared with CTD measurements at the receiver and the source arrays.
Observations of non-Rayleigh acoustic backscatter and spatial correlation
Authors: Smith Chad M. , Preston John R.
Published: June 2017

Observations of non-Rayleigh acoustic backscatter in data taken during the 2015 Littoral Continuous Active Sonar (LCAS) experiment are discussed using K-distribution shape parameter and comparison with spatial correlation width estimates. Data were collected using the Five Octave Research Array (FORA) cardioid aperture in a towed, roughly monostatic configuration. Several tracks were repeatedly measured using differing signal bands and pulse lengths allowing the use of matched filter envelope and K-distribution statistics to characterize returns in several pulse parameter configurations. Correlation width estimates are compared with non-Rayleigh regions found using shape parameter. Early work uses shallow broadside angles and vessel travel to estimate statistics for large regions providing an efficient search for clutter events. [Work supported by Office of Naval Research.]
Signal characterization using Hidden Markov Models with applications in acoustical oceanography
Authors: Taroudakis Michael , Smaragdakis Costas
Published: June 2017

The work presents a method for characterizing underwater acoustic signals using a Markov chain, with hidden variables, based on their wavelet transform. Initially, we assign to the signal a Hidden Markov Model (HMM) for which the conditional posterior probability density function seems to be the most representative using an Expectation-Maximization algorithm. Special techniques are applied to avoid over-fitting which in principle is not desirable for the sought applications. The features used for the assignment consist of two dimensional time series obtained by preprocessing of signal’s wavelet packet coefficients. Subsequently, we use an approximation of the Kullback Leibler (KL) divergence as a similarity measure among the HMMs. The approximation is obtained by employing Monte-Carlo (MC) techniques simulating the significant sampling from the HMMs posterior distributions. This technique is used in cases where the similarity of two or more signals is to be exploited. These cases include a variety of problems associated with the monitoring of the marine environment using acoustic or seismic signals. The applications to be presented here are referred to problems of geoacoustic inversions (seabed mapping) using simulated acoustic data and seismic monitoring using real data from a terrestrial seismograph to illustrate the various possible applications of the suggested method.
Head wave inversion technique using the low-frequency sound from a Robinson R44 helicopter
Authors: Bevans Dieter A. , Buckingham Michael J.
Published: June 2017

A series of underwater acoustic experiments using a Robinson R44 helicopter and an underwater receiver station has been conducted in shallow (16.5 m) water. The receiver station consisted of an 11-element nested hydrophone array with a 12 m aperture configured as a horizontal line (HLA) 0.5 m above the seabed. A microphone was located immediately above the surface. The main rotor blades of the helicopter produce low-frequency harmonics, the fundamental frequency being ~13 Hz. The tail rotor produces a sequence of harmonics six times higher in frequency. An analytical solution for the horizontal coherence for the head wave has been developed using a 3-layer (atmosphere-ocean-sediment) acoustic propagation model. By comparing the theoretical coherence with the coherence function from the data the sediment sound speed is recovered. The results from the theoretical model and an experiment conducted north of Scripps Pier off the coast of southern California are presented. [Research supported by ONR, SMART(DOD), NAVAIR, and SIO.]
Acoustic quantification of abundance, biomass, and size class of Atlantic menhaden (Brevoortia tyrannus) in a shallow estuary in Long Island, New York
Authors: Lucca Brandyn M. , Blair Hannah , Warren Joseph
Published: June 2017

Atlantic menhaden (Brevoortia tyrannus) is an euryhaline forage fish commonly found on Long Island from late spring to fall and is both ecologically and economically important to fisheries along the entire eastern coast of the United States. Schools of menhaden frequently occupy the shallow (<4 m) bays and rivers of the western Peconic Estuary on Long Island, New York. These shallow habitats are difficult to sample using traditional pelagic (i.e., net trawls) or shore-adjacent (i.e., beach seines) methods due to shallow water depths and salt marsh coastline. We conducted multiple acoustic surveys using fisheries echosounders (38, 120, and 200 kHz) and sidescan sonar between May and November in 2015 and 2016 in Flanders Bay and the Peconic River. Active acoustic surveys were capable of providing estimates of abundance, biomass, and length distribution of Atlantic menhaden. Abundance and biomass estimates for the entire western Peconic Estuary were extrapolated from survey data and showed large (order of magnitude) variations in the menhaden population in these waters from spring to fall. Length distributions of menhaden differed both among seasons and between years. Data were ground-truthed using video, photographs, and morphological measurements of Atlantic menhaden.
Optimizing passive cavitation mapping by refined minimum variance-based beamforming method: Performance evaluations in macaque models
Authors: Sun Tao , Crake Calum , Tracey Brian H. , Arvanitis Costas , Miller Eric , McDannold Nathan
Published: June 2017

Microbubble-mediated focused ultrasound (FUS) therapies harness mechanical and/or thermal effects to deliver drugs or ablate tissues. Passive acoustic mapping (PAM) enables the spatio-temporal monitoring of cavitation activity, which is critical for the clinical translation of this technique. Traditional PAM is based on delay-and-sum (DAS) beamforming, a method whose quality tends to deteriorate due to issues including multi-bubble interference, distortion in the wavefront caused by the presence of the skull, unmodeled variability of array elements, etc. To provide for robustness, here we consider the use of minimum variance adaptive beamforming to PAM and demonstrate significant improvement in image quality compared to DAS. The minimum variance distortionless response (MVDR) method was evaluated and further improved by adding diagonal loading and by using subarray covariance estimates. Results demonstrate improvements in both the resolution and image contrast compared to DAS using either traditional or a refined MVDR beamformer. The axial full width at half maximum of the microbubble activity at the focus was reduced to 79.5% and 38.5% of that in DAS image for traditional and refined MVDR beamformers, respectively. Moreover, the refined MVDR method greatly enhanced the robustness while traditional MVDR beamforming induced self-nulling effects. We anticipate that the proposed method will improve our ability to monitor and control FUS-induced cavitation-based therapies.
Transcranial histotripsy acoustic-backscatter localization and aberration correction for volume treatments
Authors: Sukovich Jonathan R. , Xu Zhen , Hall Timothy L. , Macoskey Jonathan J. , Cain Charles A.
Published: June 2017

Here, we present results from experiments using histotripsy pulses backscattered off of therapy-generated bubble clouds to perform point-by-point aberration correction and bubble cloud localization transcranially over large steering ranges to demonstrate the efficacy of these methods at improving treatment efficiency and mapping volumetric treatments. Histotripsy pulses were delivered through an ex vivo human skullcap mounted centrally within a 500 kHz, 256-element histotripsy transducer with transmit-receive capable elements. Electronic focal steering was used to steer the therapy focus through individual points spanning a 30 mm diameter volume centered about the transducer's geometric focus. Backscatter signals from the generated bubble clouds were collected using array elements as receivers. Separate algorithms, based on time-domain information extracted from the collected signals, were used to perform aberration correction and localize the generated bubble clouds, respectively. The effectiveness of the aberration correction and localization results were assessed via comparison to hydrophone measurements of the focal pressure amplitude and location taken before and after backscatter aberration correction and localization were applied. Backscatter aberration correction results showed increased focal pressure amplitudes at all steering locations tested. Localization results were in good agreement with hydrophone measurements, but were seen to display preferential bias in the pre-focal direction at larger steering distances.
Passive acoustic mapping of extravasation for vascular permeability assessment
Authors: Paverd Catherine , Lyka Erasmia , Elbes Delphine , Coussios Constantin
Published: June 2017

Prior research has demonstrated that Passive Acoustic Mapping (PAM) enables real-time monitoring of cavitation activity occurring within the vasculature to achieve drug delivery and/or opening of the Blood Brain Barrier. In the present work, we focus on whether sub-micron cavitation nuclei can be imaged once extravasated. This would provide a means of determining both vascular permeability before or after ultrasound exposure, and real-time monitoring of successful drug delivery. A key challenge in achieving these objectives is the spatial resolution of PAM. A novel bistatic setup was used to achieve sub-millimetre resolution both axially and transversely to two imaging arrays. A vertically oriented flow channel in a tissue mimicking phantom was placed at the focus of two perpendicular confocal HIFU transducers, each with a coaxial linear imaging array. Sequential acoustic excitation at 0.5 or 1.55 MHz was used to first extravasate, and then re-excite the nuclei once extravasated. The lower frequency creates stronger microstreaming while the higher frequency favors acoustic radiation force. Results have demonstrated accurate localization of extravasated nuclei at 0.4 mm from the channel. Localization was achieved using optimal beamforming PAM and verified with fluorescence microscopy. Future work will focus on in vivo applicability using murine or cancerous perfused organ models.
Functional neuro-imaging with magnetic resonance elastography
Authors: Patz Samuel , Nazari Navid , Schregel Katharina , Palotai Miklos , Barbone Paul E. , Sinkus Ralph
Published: June 2017

Evaluate changes in the shear modulus of brain tissue as a new measure of localized brain function. A spin-echo magnetic resonance elastography (MRE) sequence was modified to allow two interleaved paradigms: stimulus ON/OFF. To avoid neuronal habituation, a paradigm was active for 9s before switching to the other paradigm. After each paradigm switch, a period of 1.8 s was allowed for hemodynamic equilibrium. Seven healthy black mice were studied. An electrical current to the hind limb, ~1 mA, 3 Hz, pulse width ~250 ms, was used as the functional stimulus. A separate control scan was also performed where no stimulus was applied for either paradigm. Vibration frequency = 1kHz. In six of the seven animals, a localized increase in G’ was observed in the somatosensory and motor cortex areas, whereas no difference was observed in the control scan. The average increase of G’ = 14%. Two potential mechanisms were considered: (i) a vascular effect similar to BOLD in fMRI and (ii) calcium influx into the neurons. The first mechanism was ruled out based on results from an additional experiment where hypercapnia was induced to cause vasodilation. This implies the mechanism responsible is a primary measure of neuronal activation.
Simulating fibrin clot mechanics using finite element methods
Authors: Yeung Brandon Chung Y. , Everbach E. Carr
Published: June 2017

Blood clots inside blood vessels impede blood flow and can lead to blockage. Injection of thrombolytic agents affects the body systemically and may lead to hemorrhage. Risk is reduced with sonothrombolysis—high-amplitude pulsed ultrasound that drives micron-sized bubbles into violent oscillations, destroying the fibrin mesh of a clot. To gain insight into the 3D structure and mechanical behavior of fibrin clots, we fabricated a clot from purified fibrinogen, imaged it using a confocal microscope and 3D printed a plastic model of the image. Coordinates of fibrin connection points were entered into ANSYS, the clot finite-element-simulated for nodal displacements, and the bulk Young's modulus of the clot calculated. Simulations suggested that the elastic moduli in the three orthogonal directions were Ex = 113.5 Pa, Ey = 109.1 Pa, and Ez = 16.17 Pa. The close agreement between Ex and Ey supported the assumption of isotropy in a fibrin clot. The deviation of Ez from Ex and Ey could be attributed to the presence of the glass coverslip affecting the clot structure. Overall, results showed that confocal microscopy and simulations in ANSYS are useful in modeling clot structure and mechanics. Our next step is to simulate bubble activity inside the virtual clot.
Real-time monitoring and control of stable cavitation activity in pulsed sonication
Authors: Cornu Corentin , Guédra Matthieu , Béra Jean-Christophe , Inserra Claude
Published: June 2017

Even if bubbles collapses are commonly thought to be the key element of cell permeabilization for drug delivery applications, recent works have demonstrated the possibility of transfecting cells by gentle oscillating bubbles (stable cavitation), possibly resulting in lower cell lysis or tissue damages. Nevertheless, in a bubble cloud, both stable and inertial cavitation activities would naturally coexist, thus making difficult to quantify the contribution of both regime on the drug delivery process. To distinguish each cavitation regime, a feedback-loop process is implemented on the subharmonic component emitted from the bubble cloud generated in a water tank by a focused transducer. This feedback loop, acting at a 250µs loop rate, allows adjusting the level of subharmonic emission as well as measuring inertial cavitation activity (broadband noise emission), by real-time modulating the applied voltage to the transducer. Evidences of control of the stable cavitation activity are reported, associated with (1) the possibility of exciting a time-stable subharmonic component, (2) the lowering of the broadband noise level and (3) the saving of acoustic energy (up to 20%) to ensure a given subharmonic emission level. [Work supported by the French National Research Agency, LabEx CeLyA (ANR-10-LABX-0060) and granted by the ANR-MOST project CARIBBBOU (ANR-15-CE19-0003).]
Towards the accurate characterization of the shell parameters of microbubbles based on attenuation and sound speed measurements
Authors: Jafari Sojahrood Amin , Li Qian , Haghi Hossein , Karshafian Raffi , Porter Tyrone M. , Kolios Michael C.
Published: June 2017

Measurements of microbubble (MB) shell parameters is a challenging task because of the nonlinear dynamics of MBs. Shell parameter estimations that are typically based on solving linear models will generate inaccurate results, especially at higher pressure excitations. These approaches also often ignore the analysis of sound speed which provides useful information about the bulk modulus of the medium. In addition, the effect of MB-MB interaction is neglected. In this work, the attenuation and sound speed of monodisperse MB populations with mean diameters of 4 to 6 micron and peak concentrations of 1000 to 15000 bubbles/ml are measured for a pressure range of 10 to 100 kPa. The subharmonic pressure threshold of the solution was measured by narrowband excitations spanning from 1 to 4 MHz. The subharmonic generation pressure threshold was used to estimate an initial guess for shell viscosity and surface tension. The experimental results were fitted using numerical simulations of the Marmottant model and our recently developed nonlinear model for attenuation and sound speed. The effect of MB-MB interaction was also implemented using simulations of a lattice of interacting MBs (fitted to the measured sizes of MBs) to take into account the effect of concentration.
On acoustic characteristics of the Sound-7A coloring method
Authors: Eun Young Yi , Bae Myungjin
Published: June 2017

The most fundamental aspect of the noise influence on human beings is the size of the noise source. This paper investigates the acoustics characteristics of the sound-7A coloring system and compares each of the sound-7A colors with respect to a curve type. In this paper, the sound-7A coloring method is applied to the interlayer noise, when considering the level of noise and the energy ratio of the lightweight source to frequency band. The influence of the interlayer noise on cognitive mechanism of human beings is analyzed based on the loudness curve of human consciousness. The colors can be determined in both lightweight interlayer noise and heavy interlayer noise. As previously explained by the cocktail party effect human perceptive ability picks out some specific information among meaningless noise because it is somehow irritating to human ears. Out of some characteristics of the sound-7A coloring method, the energy ratio of the blue sound color band is nearly as twice as much for that of pink noise. This study can be utilized in our daily lives since it transfers aural perception into visual images such as illustrating lights in rainbow color coding and expressing musical instruments in special lighting performances.
On designing a new sound of the car-horn
Authors: Jee SangHwi , Kim Myungsook , Bae Myungjin
Published: June 2017

People are exposed to noise from birth to death. Hearing is considered the first human sense to awaken and the earliest to fall asleep. Human auditory sense distinguishes about 400,000 different sounds and classifies them. Noise is generally referred as unwanted sound, and human hearing is especially susceptible to noise. There are many kinds of noise such as household noise, construction site noise, transportation noise, noise between floors, and so on. Transportation noise, in particular, may harm more people since the driver as well as the people on the street are influenced by the noise. This study introduces a new friendly car-horn sound based on driver's preference through a MOS test over five different sounds. The sound has been selected based on characteristics of human auditory sense, the brainwave test, stress-index, and perceptive responses from one hundred subjects who participated in the experiment. The selected sound can be utilized in any motor vehicles available at the market so that not only the drivers honking but also the pedestrians hearing the car-horn sound can live more comfortably without hearing any annoying noise from the streets.
Spatially shaped acoustic transducer arrays
Authors: Butler Stephen C. , Frank Thomas A. , Diapis Jackeline D.
Published: June 2017

A shaped acoustic beam pattern that directs acoustic energy in the ± 45° direction with depressed acoustic energy at 0° is described. The shape of the beam pattern is controlled by area shading and the angular radius of the electro-acoustic transducer arrays. The advantage of such arrays is that acoustic energy is directed only in the required space needed at ± 45°, thus minimizing the electrical input power requirements. As a result, the number of electrical wires and the driving circuit requirements is significantly reduced because the same electrical drive voltage can be applied to all the elements in the shaped array. The shaped array described herein can be developed in the form of a one-dimensional (1-D), two-dimensional (2-D), or three-dimensional (3-D) acoustic sonar transducer array (see US Patent 9,286,418 B1, Mar. 15, 2016). [Funding from ONR.]
Comparison of different playback techniques in binaural head-related transfer function synthesis
Authors: Wiese Florian , Fallahi Mina , Blau Matthias
Published: June 2017

In binaural synthesis, the playback device (typically: headphones) can play an important role in achieving the desired perceptual authenticity. One potential source of error is the variability of headphone transfer functions when the headphones need to be taken off and on again after equalization. To avoid this issue, Erbes et al. (2012) proposed a device with miniature loudspeakers located about 5 cm away from the ears, which could remain in place. However, the device itself forms an obstacle not present in normal listening conditions and may therefore introduce direction-dependent artifacts. As an alternative, we propose a device which is placed in the subjects' ear canals. Due to its small size and the position in the ear canal, it is hoped that artifacts will be independent of the direction of sound incidence. In order to compare the two devices which remain in place to the more traditional playback over classical headphones, binaural syntheses were generated for 432 source positions (12 elevations and 36 azimuths) and related to transfer functions from real sources to microphones of a dummy head with ear canals. It was found that the agreement between synthesis and measurement was best with the in-ear device.