bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive acoustics as a tool for assessment of seagrass ecosystems
Authors: Felisberto Paulo , Jesus Sergio
Published: October 2015

Seagrass meadows are important coastal ecosystems, being the most productive biomes on Earth. The amount of produced oxygen is a key parameter for assessing the seagrass ecosystem metabolism and productivity. Several experiments conducted in Posidonia oceanica seagrass meadows have demonstrated that using active acoustic methods one can monitor the oxygen production. The acoustic method is sensitive to bubbles production and provides estimates at ecosystem level, what is an advantage to other methods. Healthy seagrass ecosystems are populated by several noisy marine taxa such as fishes and crustaceans, therefore the ambient noise can be used to assess the ecosystem metabolism and productivity. During two periods of one week in October 2011 and May 2013, acoustic and environmental data was gathered at several locations over a Posidonia oceanica bed in the Bay of Revellata in Corsica (France). The diurnal variability pattern of ambient noise characteristics (frequency band, power, directivity, and number of noisy sources) shows an evident correlation with oxygen production as measured by independent methods (optodes). The ambient noise data were dominated by impulse like waveforms associated with marine taxa. This work discusses the challenges faced on using these waveforms to invert for oxygen production.
Structure-factor model for quantifying the ultrasound scattering from concentrated cell pellet biophantoms
Authors: Franceschini Emilie , de Monchy Romain , Mamou Jonathan
Published: October 2015

Ultrasonic backscatter coefficient (BSC) measurements were performed on K562 cell pellet biophantoms with cell concentrations ranging from 0.6% to 30% using ultrasound in the 10–42 MHz frequency band. The concentrated biophantoms mimic densely packed cells with known concentrations and are thus simplified versions of real tumor. Three scattering models, the fluid-filled-sphere model (FFSM), the Gaussian model (GM), and the structure factor model (SFM), were compared for modeling the scattering of the biophantoms. The GM and FFSM assume sparse, independently, and randomly distributed scatterers and are thus suitable for modeling dilute media; however, the SFM does not contain these assumptions and therefore can model dense media accurately. First, a parameter-estimation procedure was developed to estimate scatterer size and acoustic impedance contrast (assuming that cell concentrations were known a priori) and thereby compare theoretical with measured BSCs for all studied concentrations. The SFM yielded scatterer-radius estimates of 6.4 μm, which were consistent with the cell radius measured by optical microscopy. Second, the ability of the three models to estimate the scatterer size and acoustic concentration was compared. These scatterer properties were predicted well by the SFM, whereas the GM and the FFSM underestimated cell size and overestimated acoustic concentration for the more-concentrated biophantoms.
Simulation technique and time-frequency analysis of the acoustic wave inside cancelous bone
Authors: Nagatani Yoshiki
Published: October 2015

Since the cancelous bone inside long bones has porous structure, the acoustic wave propagating inside bone may bring us useful information for the diagnosis of osteoporosis or bone healing although it is difficult to be investigated. In this paper, simulation techniques for understanding the complex wave propagation will be presented. The three-dimensional finite-difference time-domain (FDTD) method is useful for the wave simulation inside the complicated network structure. Due to the alignment of trabeculae, the pulse wave propagating inside cancelous bone separates into two wave, called the fast wave and slow wave. Here, the effect of the elasticity on the two wave phenomenon will be shown as well as the effect of the viscoelasticity. In addition to the speed and amplitude of the two waves, the frequency of the waves also changes corresponding to the structure of the medium. However, the detailed properties of the two waves are hardly revealed stably because of the wave overlapping. Therefore, a stable technique for quantitative evaluation of the wave characteristics is important. In this paper, the procedure and examples of a robust method of time-frequency analysis, named multi-channel instantaneous frequency, will be presented. These techniques help us understand and analyze the detailed wave behavior.
Quantitative ultrasound measurements in trabecular bone using the echographic response of a metallic pin: Application to spine surgery
Authors: Haiat Guillaume , Nagatani Yoshiki , Guipieri Seraphin , Geiger Didier
Published: October 2015

Bone quality is an important parameter in spine surgery, but it remains difficult to be assessed clinically. The aim of this work is to demonstrate the feasibility of a QUS method to retrieve bone mechanical properties using an echographic technique taking advantage of the presence of a metallic pin inserted in bone tissue. To do so, an experimental validation is performed and acoustical modeling is used in order to assess the influence of experimental errors. A metallic pin was inserted in bone tissue perpendicularly to the transducer axis. The echographic response of the bone sample was determined and the echoes of the pin inserted in bone tissue and in water were compared to determine speed of sound (SOS) and broadband ultrasonic attenuation (BUA), which was compared to bone volume fraction (BV/TV). A 2-D finite element model was developed to assess the effect of positioning errors. Moreover, the coupling of finite difference time domain simulation with high resolution imaging technique was used to understand the interaction between an ultrasonic wave and the bone microstructure. A significant correlation between SOS and BV/TV was found (R² = 0.6). The numerical results show the relative robustness of the measurement method, which could be useful to estimate bone quality intraoperatively.
A combined modeling and experimental investigation of ultrasonic attenuation mechanisms in cancelous bone-mimicking aluminum foams
Authors: Le Lawrence H. , Vafaeian Behzad , Nguyen Kim-Cuong T. , Adeeb Samer
Published: October 2015

Bone is composed of cancelous and cortical bones. Cancelous bone, which is more complicated than cortical bone in terms of structure, is inhomogeneous, anisotropic, and porous. The trabeculae form interconnected network with viscous marrow filling the pores. The presence of trabeculae makes cancelous bone a highly scattering medium. Trabecular bone spacing is considered an important parameter to detect change in bone tissue microstructures. However, due to high porosity and heterogeneity of human cancelous bones, the underlying mechanisms of interactions between ultrasound and cancelous bones are still not fully understood. The water-saturated aluminum foams were previously studied for the suitability of cancelous bone-mimicking phantoms. The ligament thickness and pore size of the foam samples were very similar to those of human cancelous bones. Recently, we performed the micro-scale elastic modeling of broadband ultrasound traveling through the water-saturated aluminum foams using the standard Galerkin finite element method. The simulated results were compared with the experimental measurements using the derived broadband ultrasound attenuation coefficients. The results strongly suggested that wave scattering and mode conversion were the dominant attenuation mechanisms of ultrasound propagating in aluminum foams. The study further demonstrated the capability of the finite element method to effectively simulate the signatures of the ultrasound signals propagating in fluid-filled weakly absorptive porous structures.
Ultrasonic guided waves in bone system with degradation
Authors: Thakare Dhawal , Belanger Pierre , Rajagopal Prabhu
Published: October 2015

This paper investigates the feasibility of using ultrasonic guided waves for assessing the cortical bone and hence detect conditions such as osteoporosis. Guided wave propagation in bone systems modeled as multi-layered tubular structures consisting of anisotropic bone filled with viscous marrow and surrounded by tissue is studied using the Semi Analytical Finite Element (SAFE) method. Effects of changes to cortical bone thickness and mechanical properties are investigated. An attempt is also made to consider bone anisotropy in the models.The results, validated by experiments with bone phantoms, show that material and geometric condition strongly impacts the velocity of guided waves supported in the bone system. Identification of optimal guided wave modes for practical assessment is also discussed.
Axial transmission assessment of trabecular bone at distal radius using guided wave
Authors: Pereira Daniel , Abid Alexandre , Diotalevi Lucien , Fernandes Julio , Belanger Pierre
Published: October 2015

The diagnosis of osteoporosis at skeletal sites composed mainly of trabecular bone, such as distal radius, can be considered clinically more relevant then cortical bone regions. Thus, the possibility to merge the potential of guided waves method to the clinical relevance of trabecular bone assessment is extremely motivating and has not yet been explored in details. Therefore, the objective of this paper is to investigate the feasibility of guided waves method to detect variation in the mechanical properties of trabecular bone at the distal radius using axial transmission. Due to the complexity of the distal region, three-dimensional finite elements simulations were performed using a bone model built from a computed tomography image of a human radius. The accuracy of the numerical model was experimentally validated using a bone phantom. The simulated excitation was transmitted to the radius using a longitudinal load applied to a small circular region at the extremity of distal radius. The identification of the guided waves was evaluated using 2DFFT transform. The results showed that the excitation imposed at the extremity of the distal radius creates guided waves that propagate along the long bone. Furthermore, the identified modes showed high sensitivity to the trabecular bone properties.
A comparative study of acoustics and vibration analysis for wearing bearings
Authors: Snow Bethany , Dunn Chris , Lin Lin , Smith James
Published: October 2015

Monitoring of progressive wear and early diagnosis of damage are critical to a rotating machine to avoid dangerous, costly, time consuming failures. A common symptom of wear in rotating machines is characterized by an increase in noise and /or vibration levels. It is usually monitored by either accelerometers or acoustic emission sensors, both of which are required to be mounted on the machine. Acoustics measurement using microphones has its unique non-contact advantage of monitoring the sound that caused by the wearing. Some work has been done on investigating the power of the acoustic signals of wearing machines; however, the principal indicator of failure onset and the relation between the spectra of the vibration signal and the non-contact acoustic signal is unclear. In this project, both acoustic and vibration signals were measured to investigate a machine with bearings of different degrees of wear. Acoustic signal were recorded at various azimuth settings and compared to the vibration signal. Frequency analysis and signal processing techniques were applied to compare the information contents and sensitivities of those two measurements.
A micromachined microphone based on a field effect transistor and an electret for low frequency acoustic detection
Authors: Shin Kumjae , Sung Min , Moon Wonkyu
Published: October 2015

Miniaturized microphone has sensitivity degradation in low-frequency region because most microphones use a capacitive-type transduction mechanism which has low-frequency cut-off. Therefore, detection of low-frequency sound is carried out using a microphone with large membrane and a large back chamber. To overcome this limitation, a micro-machined microphone based on a FET (Field effect transistor) and electret has been reported, and the feasibility of this system was demonstrated. The electric field due to the electret modulates the channel of the FET embedded in the membrane. The acoustic signal causes the FET mounted on the membrane to vibrate, which changes the separation between the channel of the FET and the electret. The resulting change in the electric field modulates the conductivity of the channel. The use of an integrated FET as a sensing mechanism in response to the electric field from the electret makes it possible to detect the displacement of the membrane directly. We describe a theoretical model for the low-frequency operation of this system and provide a comparison with experimentally measured results. A sensitivity analysis for the transduction mechanism is carried out, and the frequency response of the microphone is characterized using an acoustic measurement setup developed for low-frequency sound.
System and method for determining the level of a substance in a container based on measurement of resonance from an acoustic circuit that includes unfilled space within the container that changes size as substance is added or removed from the container
Authors: Cameron Robert H.
Published: October 2015

This abstract is for a poster session to describe a patent application made to the patent office in November 2012. The patent describes a system and method for determining the level of a substance in a container, based on measurement of resonance from an acoustic circuit that includes unfilled space within the container that changes size as substance is added or removed from the container. In particular, one application of this device is to measure the unfilled space in the fuel tanks of vehicles such as cars and trucks. For over 100 years, this measurement has been done by a simple float mechanism but, because of the development of tank design for vehicles that involve irregular shapes this method is increasingly less accurate. The proposed device will overcome these limitations and should provide a much more accurate reading of the unfilled space and therefore the amount of fuel in the tank since the total volume of the tank is known.
Effects of noise exposure in combination with exposures to JP-8 jet fuel
Authors: Mattie David R. , Fechter Larry D. , Fisher Jeff W. , Stubbs John E. , Guthrie O'neil W.
Published: October 2015

The objective was to evaluate the potency of JP-8 jet fuel to enhance noise-induced hearing loss using inhalation exposure to fuel and simultaneous exposure to noise with male & female Fischer 344 (F344) rats for 6 h/d, 5 d/wk for 4 wk (200, 750, or 1500 mg/m3). Parallel groups of rats also received nondamaging noise (85 dB) in combination with fuel, noise alone (75, 85, or 95 dB), or no exposure to fuel or noise. Computer software was used to generate a pure and precisely filtered white noise file of one octave band, centered at 8 kHz. The filtered file was then played through electrodynamic shakers that induced vibration from the outside in the metal plenum at the bottom of each exposure chamber to produce noise. Significant concentration-related impairment of auditory function measured by distortion product otoacoustic emissions (DPOAE) and compound action potential (CAP) threshold was seen in rats exposed to combined JP-8 (1500 mg/m3) plus noise (85 dB) with trends toward impairment at 750 mg/m3 JP-8 plus noise (85 dB). JP-8 alone exerted no effect on auditory function. Noise was able to disrupt DPOAE and increase auditory thresholds when noise exposure was at 95 dB. Two additional studies with JP-8 (1000 mg/m3) and noise (85 dB), one with F344 rats and one with Long Evans rats did not affect auditory function. However, a pilot assessment indicated a central auditory processing dysfunction (i.e., impaired brainstem encoding of stimulus intensity) among F344 and LE rats exposed to JP-8 alone and JP-8 with noise.
A key test of the theory of critical phenomena using acoustics in liquid helium
Authors: Maynard Julian D.
Published: October 2015

A significant success of modern theoretical physics has been in the study of critical phenomena, where a system displays singular properties while undergoing a transition between different phases of matter. The modern theory (recognized by a Wolf Prize and a Nobel Prize) involves the notions of length scale invariance, power law singularities, the renormalization group etc. A significant experimental test of the theory has been the study of the transition between normal liquid and superfluid behavior of liquid helium-4 (recognized with a London Prize). The singular properties which characterize a critical transition typically involve a divergence in a susceptibility, such as a heat capacity, compressibility, or other property which may couple to a local configuration of atoms or molecules. Since these latter properties may be probed with sound waves, acoustics can be a useful probe of critical behavior. In the case of superfluid helium there are five fundamentally different modes of sound propagation, and this acoustic abundance contributed to the success of the critical phenomenon theory test. This talk will review the theory of critical phenomena, describe the different modes of sound propagation in superfluid helium, and summarize the results of the key test of the critical phenomenon theory.
Control of amplification of ground vibration in joist-framed buildings
Authors: LoVerde John , Dong David W.
Published: October 2015

For multifamily buildings near railroads, it is possible to directly measure the ground vibration caused by passing trains. The indoor vibration levels are determined by predictions of the transfer of vibration from ground to foundation, propagation up the building, and amplification by floor resonances. Large amounts of amplification have been observed in lightweight joist-framed structures. One mitigation method is to stiffen the structural system, both to raise the resonant frequency to a less objectionable range, and to reduce the magnitude of the resultant vibration. However, the benefit of this mitigation has rarely been quantified or presented. Measurements were performed in a multifamily building adjacent to railroad tracks that had been stiffened over a portion of the building. Vibration propagation and amplification were measured in the stiffened and non-stiffened portions, and the effect of mitigation is evaluated in the context of anticipated results and actual measured levels.
Reconsideration of forensic acoustics
Authors: Hollien Harry
Published: October 2015

The high talent level of in our Society members is unquestioned. However, it appears that some of us have not yet reached full maturity relative to Forensic Acoustics. While the adversarial aspect of Forensics does not parallel our investigational rigor, the number of variables they face is much greater than ours. Accordingly, development of acoustic systems for forensic use requires different approaches than we typically use. Speaker identification (SI) constitutes a good example here. Fifty years ago, it was agreed that a valid SI system could be quickly created but that has not happened. In response, the undersigned adapted the scientific method (and its standards) as a model for SI system development. The resulting research was modestly successful but the approach was not considered “useful”. Later, the Daubert test confirmed this model (but ordinarily was circumvented). Now, the National Academy of Science has verified these models and is insisting on proper developmental protocol. It is no longer permissible to develop an algorithm-based device, and apply it, without proper demonstration of its validity. The impact of these research-based standards—now required for creating Forensic systems—will be discussed, as will possible responses.
Evaluating acoustic measurements of creaky voice: A Vietnamese case study
Authors: Pincus Nadya , Athanasopoulou Angeliki , Miller Taylor L. , Vogel Irene
Published: October 2015

It has been proposed that there are two broad categories of creaky voice (CV), laryngealized and aperiodic. Moreover, several subdivisions have been proposed for both categories (Keating & Garellek, 2015), and various combinations of acoustic properties have been associated with each. It remains unclear, however, how to determine which type of CV a language has and which acoustic measurements to rely on. We address this problem with two rising tones in Vietnamese differing in phonation. All of the phonation measurements we tested with ANOVA were statistically significant (p < .01) in the distinction between the two tones, and thus inconclusive as to the type of CV. We propose that an additional binary logistic regression analysis be applied to the various measurements to determine the extent to which each one contributes to classifying creaky vs. modal vowels; and this, in turn, can inform us about the nature of the CV in the language. Specifically in Vietnameses, we found that HNR yields the strongest classification result (84%); the others were closer to chance (58–68%). We can thus conclude that the CV used in Vietnamese is the aperiodic type, as evidenced by the role of irregular F0 as opposed to the other phonation properties.
Perceptual load of divided attention modulates auditory-motor integration of voice control
Authors: Liu Hanjun , Liu Ying , Guo Zhiqiang
Published: October 2015

The present study sought to examine how the auditory-motor processing of feedback errors during vocal pitch regulation is modulated as a function of divided attention. Subjects were exposed to pitch perturbations in voice auditory feedback and flashing lights on the computer screen, during which they were asked to divide their attention to both auditory and visual stimuli by counting the number of both of them. The presentation rate of the visual stimuli (inter-stimulus intervel) was manipulated to produce a low, intermediate, and high attentional load. The results revealed that, as compared to the low and intermediate attentional load conditions, the high attentional load condition elicited significantly smaller magnitudes of vocal responses but larger amplitudes of N1 and P2 responses to pitch feedback perturbations. These findings demonstrate the effect of attentional load on the auditory-motor processing of pitch feedback errors during divided attention, suggesting that perceptual load of visual attention interferes the attentional modulation of auditory-motor integration in voice control.
Digit recognition with phonological features
Authors: Arora Vipul , Lahiri Aditi , Reetz Henning
Published: October 2015

Our project aims to identify English digits, employing an approach to speech recognition built on principles derived from phonological knowledge and neurolinguistic experiments on how the humans perceive and process speech. This is in contrast to current ASR systems, which rely upon statistical machine learning using thousands of hours of speech training data and vast amount of computations, with little reliance on any aspect of phonological features. We focus on digits to test our approach with a circumscribed set of elements, which have considerably different phonemes (e.g., the sounds in ‘five’, ‘two’ and ‘six’ are all different). Our system converts the acoustic signal to a set of phonological features whose combinations are used to access words. The features are speaker and language independent, with the intention of building a system easily adaptable to other languages without re-training the acoustic front-end. A number of acoustic parameters (e.g, LPC, spectral and energy differences) were investigated and their relative importance compared for a robust estimation of phonological features; e.g., spectral slope below and above 2500 Hz disambiguates sibilants. However, distinguishing sonorant sounds requires a range of other parameters. We tested our system on the American English TIDIGIT database achieving unexpected success rates.
Understanding southern British, Glaswegian, and Spanish English accents: Speech in noise and evoked potentials
Authors: Hödl Petra , Pinet Melanie , Evans Bronwen , Iverson Paul
Published: October 2015

Speech recognition in noise is affected by the accents of the speakers and listeners, but it is not clear how overall accuracy is linked to the underlying perceptual and lexical processes. The present study investigated speech recognition for two native-accent groups (Southern British English and Glaswegian) and one non-native group (Spanish learners of English). Listeners were tested behaviorally on speech-recognition in noise, and using EEG measures of vowel perception (cortical evoked potentials to vowel spectra change) and lexical processing (N400). As expected, southern British English listeners were most accurate for southern British speech, Glaswegians were accurate for both Glaswegian and southern British English speech, and Spanish speakers had particular difficulty with Glaswegian. The EEG results demonstrated differences between groups in terms of both vowel and lexical processing. In particular, Glaswegian listeners differed in their lexical processing for the two native accents despite having similar speech-in-noise accuracy, and Spanish speakers appeared to use contextual information less than the other two groups. The results begin to demonstrate how differences at a perceptual level can be compensated for during lexical processing, in ways that are not apparent purely from recognition accuracy scores.
Effect of menstrual phase on dichotic listening
Authors: Morris Richard J. , Smith Alissa N.
Published: October 2015

Women using birth control and those not using it completing weekly dichotic listening sessions for nine weeks. Results indicated no differences between the two groups for right ear advantage.
The effect of semantic cues on intelligibility: A comparison between spectrally sparse speech and natural speech in noise
Authors: Shahsavarani Bahar , Carrell Thomas , Samal Ashok
Published: October 2015

Listeners are known to make use of contextual cues when perceiving speech. Using contextual information is even more important when listening to distorted or difficult speech signals. For example, listeners benefit from contextual cues to compensate for the absence of fine acoustic-phonetic information when listening to natural speech in noise. In the present investigation, the effect of context was compared between four- and eight-channel spectrally degraded speech (Shannon et al., 1995) versus natural speech-in-noise (0 dB SNR). Spectrally degraded speech simulates the primary information transmitted by cochlear implant devices. The results demonstrated that eight-band signals received benefit from context to the same extent as natural speech in noise. In contrast, four-band signals provided significantly less benefit from context than natural speech in noise. The most parsimonious explanation of this pattern of results is that listeners need a threshold amount of acoustic information to make use of context equally, regardless of the type of distortion. Alternatively, the results could be explained by assuming that listeners employ different strategies depending on the overall acoustic characteristics of the speech signal. Future experiments will distinguish between these alternatives.
Acoustical design of performance and rehearsal spaces influenced by instrument directivity
Authors: D'Antonio Peter
Published: October 2015

The sound that we hear in a music space is determined by the direct sound, as well as the early and late reflections from the room’s surfaces, so instrument directivity and reflection control are of primary interest. Spatially directed sound by individual instruments and musical ensembles is controlled by the selection and placement of absorptive, reflective, and diffusive boundary surfaces, which contribute to the room’s preference for both the musicians and the audience. We will describe how these surfaces are measured and characterized for directional and random incidence and how they have been used in many types of musical environments. In this presentation, we will discuss and present before and after measurements in the design of an individual practice room addressing room modes; describe the essential ingredients in an ensemble rehearsal space; present before and after perception questionnaires for a variable acoustics modular performance shell for small music ensembles and a symphony orchestra; describe a stage canopy optimization as a function of the support objective measure and present computer model coverage predictions addressing rear wall and overhead canopy treatments in an auditorium.
Using multi-channel anechoic recordings to represent source directivity in room acoustics models to improve auralizations
Authors: Vigeant Michelle C. , Wang Lily M. , Rindel Jens Holger
Published: October 2015

A series of studies were conducted to investigate the effects of different sound source directivity representations on perceived differences in auralizations. The first study (Wang & Vigeant 2008) showed that subjects could not distinguish between auralizations created using both omnidirectional and measured static directivities of individual instruments. Differences may not have been observed since source directivities were not available for all octave bands of interest (125–8000 Hz). Significant differences were perceived between the auralizations generated using an omnidirectional source and a highly directional source for all bands. For the second study (Vigeant, Wang, & Rindel 2011), the effects of using 4- and 13-channel solo instrument anechoic recordings versus single channel recordings on realism and source width were evaluated. In general, the results showed an improvement in realism and decrease in source width with an increasing number of channels. In the final study (Vigeant, Wang, & Rindel 2008), 5-channel solo instrument anechoic recordings for two orchestral pieces were used to investigate the effects of using multi-channel and multi-source representations of an orchestra on realism, source depth, source width, and ease of distinguishing between instrument parts. For some of the cases studied, significant differences were found with the most complex representation of the orchestra.
Quantification of time varying directivity of musical instruments in an orchestral context
Authors: Davidson Madeline A. , Wang Lily M.
Published: October 2015

At the University of Nebraska, previous research has been done in the quantification of time varying directivity of played musical instruments using 13 channel anechoic recordings of solo passages. The proposed quantifiers involve measures of the extent to which directivity changes in magnitude as well as how often the directivity changes in spatial direction, using various time windows of analysis from 0.2 to 1 s. In this paper, these proposed quantifiers are applied to 5 channel anechoic recordings of a full orchestra for a Brahms symphony and a Mozart symphony. With silent sections removed from the recordings, the time varying directivity properties of musical instruments are more accurately examined within the context of played notes from two stylistically different symphonies.
Balancing sight and sound in heritage worship buildings
Authors: Clayton Dan
Published: October 2015

Buildings for traditional religious gathering and time-honored worship practice require a balance of highly valued acoustical qualities such as reverberance for liturgical music, ensemble for choral singing, responsiveness for congregational participation, and clarity for intelligible speech. Geometry, dimensions, proportions, cubic volume, and boundary materials are critical elements of acoustical success. Many old European worship buildings are admired for their particularly fine blending of these criteria, and often cited as benchmarks for how buildings in the United States should look and sound. Although many heritage U.S. worship buildings look like their European precedents in terms of layout, shape, and size, a critical design element was modified, upsetting the acoustical balance. Boundary materials became lighter and thinner, making construction easier, faster, and less expensive. Acoustical upgrade of these existing buildings in the context of historic preservation/restoration brings additional design complexity, requiring equal measures of compromise from owner, users, acoustician, architect, and engineers. The acoustician's dilemma becomes “what we see may not be what we hear,” as acquired acoustical expectations are upended by actual conditions. This paper will describe these differences and explore approaches to acoustical enhancement within limitations of the buildings themselves plus further constraints of contemporary preservation practice.
Worship space acoustics: Design needs, trends, and issues for sacred spaces, relative to traditional and contemporary worship styles
Authors: Riedel Scott , Schaefer Craig
Published: October 2015

Concerns and goals for worship space acoustic design include the need for clear, intelligible speech, well blended, balanced, and projected music, and encouraging robust participation by the congregation in sung and spoken parts of a service. Also important are the attenuation of noise and control of acoustical anomalies that could interrupt, mask, or distort the critical expressions of speech and music. Achieving these goals includes careful attention to such factors as various cubic air volumes, unique geometric forms, functional proximities, and interior finish material selections. These factors are important to both improving existing rooms and in creating new designs. A current challenge is that of accommodating different musical styles (from traditional compositions and instruments to contemporary and ethnic forms) within the same space. Practical issues may include client understanding of differences between A/V systems and their capabilities vs. architectural room acoustics, and realities of budget limitations and value engineering. Before and after case-study examples exploring these goals, issues, and design solutions will be presented and discussed, including examples from the new publication, “Worship Space Acoustics, Three Decades of Design.”
Practical lessons in acoustical design learned from recent worship space projects
Authors: Markham Benjamin
Published: October 2015

In the last 25 years of worship space acoustics consulting projects (and building on experiences of the 25 years before that), consultants at Acentech have learned many important lessons about these unique and important spaces. Throughout that time period, the evolution of worship style has necessitated thoughtful new design approaches to worship space acoustics. Acentech consultants have learned lessons regarding the complex interplay between support for congregational singing and appropriate reverberation control for contemporary worship music. The equally complex interplay between traditional music and intelligibility of a preacher’s speech has also taught profound and lasting lessons. Silence plays a critical and fundamental role in promoting a contemplative and prayerful environment—another important lesson learned. Using examples from the Acoustical Society’s new Worship Spaces book, this presentation will illustrate practical lessons from these and other projects in Acentech’s recent experience with worship facilities.
Design and renovation of worship spaces at Fourth Presbyterian Church in Chicago
Authors: Schuette Dawn , Nelson Smid Jennifer
Published: October 2015

Fourth Presbyterian Church is among Chicago’s most iconic buildings. Designed by Ralph Adams Cram, it was dedicated in 1914. Threshold Acoustics worked alongside Gensler on a 5-story addition to the Fourth Church facilities that provided needed worship and program space in celebration of their centennial. The Genevieve and Wayne Gratz Center was included as a case study for the publication “Worship Spaces Acoustics: Three Decades of Design.” It houses the 350-seat Buchanan Chapel, which is used as overflow for holiday services, intimate worship services, Children’s Chapel, music performances, and weddings. Threshold Acoustics is currently working with Fourth Church on the restoration of their historic Skinner Organ in the sanctuary. An acoustic study of the sanctuary was completed to evaluate and determine the current challenges the organ faces to carry sound to all locations within the Nave. The renovations to the organ and chamber are underway and are to be finished by December 2015 for holiday services. This paper will describe Threshold's acoustic design for the Gratz Center and Sanctuary.
Insights into mechanisms of sonothrombolysis using high speed imaging
Authors: Villanueva Flordeliza
Published: October 2015

Thrombotic arterial occlusion is the major cause of acute cardiovascular syndromes such as stroke and myocardial infarction. Exposing the thrombus to microbubbles in the presence of ultrasound facilitates thrombus disruption, and is thus a potentially powerful therapeutic strategy for thromboembolic diseases. However, optimization of “sonothrombolysis” is constrained by a lack of understanding of underlying mechanisms for blood clot disruption in response to ultrasound-induced microbubble vibrations. We tested the hypothesis that inertial cavitation induces mechanical clot disruption by optically characterizing lipid microbubble interactions with thrombus + ultrasound using an ultra-high speed microscopy imaging system capable of imaging at MHz frame rates. A microscope/acoustic stage was used to hold an experimentally created thrombus and microbubbles, which were insonified (1 MHz) during synchronized high speed imaging. Large amplitude microbubble oscillations in response to an inertial cavitation regime caused thrombus deformation and pitting. These data implicate a direct mechanical effect of oscillating microbubbles on mediating clot disruption.
Microbubble pumps: Ultrasound theragnostic agents
Authors: Holland Christy K. , Shekhar Himanshu , Bader Kenneth B.
Published: October 2015

Cardiovascular disease is the number one cause of death worldwide, and thrombo-occlusive disease is a leading cause of morbidity and mortality. Ultrasound has been developed as a tool to induce the release, delivery, and enhanced efficacy of a thrombolytic drug (rt-PA) and bioactive gases from echogenic liposomes. By encapsulating drugs into micron-sized and nano-sized liposomes, the therapeutic can be shielded from degradation within the vasculature until delivery is triggered by ultrasound exposure. Insonification accelerates clot breakdown in combination with rt-PA and ultrasound contrast agents, which nucleate sustained bubble activity, or cavitation. Mechanisms for ultrasound enhancement of thrombolysis, with a special emphasis on cavitation and radiation force, will be reviewed. The delivery of bioactive gases from echogenic liposomes to promote vasodilation and cytoprotection will also be discussed.
Molecular mechanisms of the effect of ultrasound on the fibrinolysis of clots
Authors: Chernysh Irina N. , Everbach E C. , Purohit Prashant K. , Weisel John W.
Published: October 2015

Our objective was to identify mechanisms for the ultrasound-enhanced acceleration of tissue-type plasminogen activator (t-PA)-induced fibrinolysis of clots. Measurements of turbidity as a function of time, used to characterize quantitatively the effects of ultrasound, showed that the ultrasound pulse-repetition frequency affected clot lysis times, but there were no thermal effects. Ultrasound in the absence of t-PA produced a slight but consistent decrease in turbidity, suggesting a decrease in fibrin diameter due solely to the action of ultrasound, likely caused by an increase in protofibril tension because of vibration from ultrasound. Changes in fibrin network structure during lysis with ultrasound were visualized in real time by deconvolution microscopy, revealing that the network becomes unstable when 30–40% of the network was digested, whereas without ultrasound, the fibrin network was digested gradually and retained structural integrity. Fluorescence recovery after photobleaching during lysis was used to characterize the kinetics of binding/unbinding and transport. Ultrasound causes a decrease in the diameter of fibers due to tension as a result of vibration, leading to increased binding sites for plasmin(ogen)/t-PA. The positive feedback of this structural change together with increased mixing/transport of t-PA/plasmin(ogen) is likely to account for the observed enhancement of fibrinolysis by ultrasound.
Histotripsy for liquefaction of large extravascular hematomas for fine-needle aspiration: Feasibility study
Authors: Khokhlova Tatiana D. , Matula Thomas , Haider Yasser , Monsky Wayne
Published: October 2015

Intra- and extra- muscular hematomas result from repetitive injury, or sharp and blunt limb trauma. There are currently no short-term treatment options for large hematomas, only lengthy conservative treatment. The goal of this work was to evaluate the feasibility of histotripsy to liquefy extra-vascular hematomas for subsequent fine-needle aspiration. Cavitation histotripsy (CH) and boiling histotripsy (BH) were applied to liquefy 50-mL clots in an in vitro gel phantom. 1 MHz and 1.5 MHz transducers were used with duty cycles of 1–2% for BH and 0.3–0.5% for CH, pulse durations 10 ms for BH, and 3.3–5 çs for CH, treatment duration 5–60 s and peak focal pressures of p+ = 70–100 MPa, and p- = 15–25 MPa. The liquefied lysate was aspirated with a 18–21 gauge needle. The lysate was analyzed by histology and sized in a Coulter counter. Under the same exposure duration, BH lesions were 1.5–2 times larger than CH lesions. 99% of lysate particulates were smaller than 10 çm. CH-aided liquefaction was slower, but the voids were more regularly shaped, facilitating easier aspiration. A combination of BH and CH may be most optimal for liquefaction. [Work supported by NIH K01 EB 015745 and Washington State Life Science Discovery Fund (Grant No. 3292512).]
Design, characterization, and performance of a dual aperture, focused ultrasound system for microbubble-mediated, non-thermal ablation in rat brain
Authors: Sutton Jonathan , Power Yui , Zhang Yongzhi , Vykhodtseva Natalia , McDannold Nathan
Published: October 2015

Submegahertz ultrasound (US) with microbubbles (µB) can ablate brain tissue: a low amplitude (< 1 MPa) alternative to thermal ablation. Single element transducers at transcranial frequencies have broad axial profiles compared to the size of targets in small animals. Thus, we sought a system to ablate millimeter volumes in normal and tumorous rat brain non-thermally using US and µB. The system consisted of two transducers oriented at 120°, driven at different frequencies (F = 837 kHz, ΔF = 30 Hz) to reduce the depth-of-field by 78%. To monitor cavitation, a passive detector (650 kHz) was confocally aligned with the therapy field. Targets were registered stereotactically. µB injections (100, 200, and 400 µl/kg) with 5-minute sonications proceeded at acoustic pressures relative to the in vivo cavitation threshold (0.3–0.6 MPa) determined a priori. Following MRI and sacrifice (1 h, 4 days, 10 days), tissue was fixed and stained. At 1 h, small lesions (<2 mm) were selectively comprised of stenotic capillaries with macrophage infiltration and neuronal damage. As lesions grew, stenotic capillaries within this escalating margin increased, along with neuronal damage. T2* lesions larger than 4 mm exhibited necrosis, cyst, and tissue removal histologically after four days. Persistent, strong (>5 dB) inharmonic energy indicated formation of large ablation volumes along the US path. Low level (<2 dB) or sporadic (<50%) cavitation indicated incomplete ablation. Results and mechanisms, especially with respect to ischemic stroke, will be discussed.
An empirical model of size-isolated ultrasound-triggered phase shift emulsions
Authors: Mercado Karla P. , Snider Lindsay , Radhakrishnan Kirthi , Haworth Kevin J.
Published: October 2015

High-speed mechanical agitation is commonly used to produce microbubbles and droplets for ultrasound imaging and therapy. This technique results in a high concentration (~1010 particles/mL) of polydisperse particles (less than 400 nm to greater than 15 μm in diameter). Differential centrifugation has been used to isolate microbubbles and droplets of specific sizes. In our prior work, we have isolated droplets between 2 μm and 5 μm. In the current work, we have isolated different sizes of droplets by adjusting centrifugation speeds. Our size-isolation protocol increased the fraction of droplets between 1 μm and 3 μm from 8% for non-centrifuged droplets to 87% for differentially centrifuged droplets. An empirical model for the size distribution after differential centrifugation was developed. The measured fraction of droplets in the supernatant and pellet for all sizes after a single centrifugation was used in the empirical model. There was a 3% difference in the volume-weighted mean diameter of the experimentally measured and empirically modeled size distributions. The coefficient of variations of the experimentally measured and empirically modeled size distributions were 24% and 22%, respectively. The empirical model allows for determining appropriate centrifugation parameters to obtain desired size distributions. [Work supported in part by NIH grant KL2 TR000078.]
Standard-target calibration of sonars for imaging and scattering measurement: An ISO-standard development
Authors: Foote Kenneth G. , de Moustier Christian
Published: October 2015

Given a standard target of known acoustic scattering properties, the combined transmit–receive transfer characteristics of an active sonar system can be determined by measuring the response due to the target placed at specified positions in the sonar transmit and receive beams. These measurements are repeatable to ±0.1 dB, establishing an absolute reference when measuring the scattering properties of unknown targets. This standard-target sonar-calibration method is in worldwide use with scientific echo sounders and multibeam sonars that provide the water-column signal, yet no international metrological standard defines it. To prescribe protocols for this method, which has a demonstrated applicability over the frequency range from 1 kHz to several megahertz, an effort was initiated in 2014 within the International Organization for Standardization (ISO) Technical Committee 43 (Acoustics) Subcommittee 3 (Underwater Acoustics). The associated Working Group 4 (Standard-target method of calibrating active sonars) has formulated an outline of the intended ISO standard. The elements of this will be reviewed.
Calibration of high frequency MEMS microphones and pressure sensors in the range 10 kHz–1 MHz
Authors: Ollivier Sébastien , Yuldashev Petr V. , Desjouy Cyril , Karzova Maria , Salze Edouard , Koumela Alexandra , Rufer Libor , Blanc-Benon Philippe
Published: October 2015

In the context of both nonlinear acoustics, and downscaled acoustic or aero-acoustic experiments, the characterization of the high frequency response of microphones and pressure sensors remains a critical challenge. In the case of the design of new MEMS microphones and shock pressure sensors with response in the frequency range of 10 kHz–1 MHz, this question was addressed by the definition of a new calibration method based on a spark source that generates spherical weak shock acoustic pulse. Waves are short duration non-symmetric N-waves with duration of about 40 microseconds and front shock rise time of the order of 0.1 microsecond. Taking advantage of recent works on the characterization of such pressure waves using an optical interferometer, and considering non linear propagation of weak shockwaves, we were able to estimate the incident pressure wave in the range of 10 kHz–1MHz. Hence, from the output voltage of the microphones, the frequency response was obtained in this range. The method applies whatever the transduction principle and the sensor mounting. [Work supported by the French National Agency for Research (SIMI 9, ANR 2010 BLANC 0905 03, and LabEx CeLyA ANR-10-LABX-60/ANR-11-IDEX-0007).]