bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between floor and ceiling panels in presence of a fibrous material in the cavity
Authors: Scelo Thomas
Published: May 2008

The mechanisms governing the acoustic transmission through building elements such as floor/ceiling assemblies are complex. The vibroacoustic interactions between the finite size structure and the enclosed volume are, in particular, rendered more complex at low frequencies when the finite dimensions of the building are taken into consideration. A model developed to predict the low frequencies vibroacoustics response of mutliplates systems offers the opportunity to explore, among other geometrical and material parameters, the effects of a fibrous material in the ceiling plenum on the acoustics behaviour of the whole structure. This paper presents the theoretical approach employed to predict the interactions between the floor, the ceiling panel and the enclosed volume. It also explores the effects of varying the material characteristics and overall thickness on these interactions.
Field airborne and impact sound insulation of wood truss floor systems
Authors: Himmel Chad N. , Kupersztoch Daniel J.
Published: May 2008

A series of field measurements on wood truss floors of various types was recently completed at four residential apartment complexes. About 40 floors with different floor finishes, gypsum concrete underlayment, noise control underlayment systems, truss span lengths, ceiling types, and resilient metal channel types were constructed and measured. Trusses were all similar engineered prefabricated parallel chord wood trusses. Room volumes and room absorptive characteristics are varied and nonstandard. Measurements are normalized according to ASTM E 1007 and proposed normalized impact sound rating (NISR) procedures to provide a reasonably consistent set for analysis. Low frequency measurements were conducted to 12.5 Hz one-third octave band. For both transmission loss and impact sound, many of the results compare well with predictions using simple regression analysis developed by others using variables such as the mass of the layers, truss depth and spacing, insulation thickness and density, and resilient metal channel spacing. The measurements and results will be presented in the paper.
Effect of the frequency spectrum trend on the determination of the weighted normalized impact sound pressure level for floor structures
Authors: Bettarello Federica , Fausti Patrizio
Published: May 2008

The most common floor constructions in Italian buildings are composed of two parts: the structural one, made of concrete beams and perforated bricks, and the floating floor. The results of the in situ measurements of the impact sound pressure level, realized on the structural part of the floors, show a frequency spectrum trend that increases with the frequency. The spectrum is also characterized by many peaks and dips at the high frequency range that strongly influence the determination of the weighted normalized impact sound pressure level, also for structures with similar mass and geometry. The frequency trend of the beam and brick structures is completely different from the characteristic spectrum of homogeneous concrete slabs or lightweight structures. Considerations on how those differences can influence the obtainable results in terms of the reduction of impact sound pressure level referred to the same floating floor typology, the spectrum adaptation terms and the other acoustic quantities described in the standards are reported.
Investigations on real-size coupled rooms based on Bayesian estimation method
Authors: Su Zuhre , Woolworth Dave , Xiang Ning
Published: May 2008

As a case study, this work aims to experiment coupled-volume systems with scientifically grounded quantifiers using Bayesian analysis, a reliable analysis method in evaluating effects of different parameters on sound energy decays of coupled rooms [Xiang & Goggans, J. Acoust. Soc. Am. 110, 1415 - 1424 (2001)]. This research uses the well-defined indicators developed by Xiang and Goggans to assess sound energy decays in a real-size hall. Derived from the model-based Bayesian inference, level differences (ΔL), diverse decay times, and decay time ratios are the quantitative descriptors of sound energy decays in acoustically coupled spaces. The room impulse responses of Howorth Theater in Oxford, Mississippi coupled to the adjacent lobby are experimentally measured in the case study. The two rooms are connected with two separate apertures and have distinct natural reverberation times that allow experimenting different setups for probable acoustical coupling at certain locations. In this paper, frequency, and location dependence of double-slope characteristics of sound energy decays are discussed.
Towards a realistic ray tracing for room acoustics
Authors: Durany Jaume , Garriga Adan , Mateos Toni
Published: May 2008

We present a recently developed ray tracing engine for room acoustics computations whose improved physics provide more realistic results than present state of the art methods. Ray tracing has been widely applied within the graphics community to obtain realistic shadings, but the computational cost reduction has oriented efforts towards fast computations of apparently realistic images rather than physically correct results. In the case of audio ray tracers, a similar tendency has led to relatively fast shading algorithms that often miss its physical basis, preventing the resulting impulse responses from converging to physically correct solutions. Our engine improves this situation by focusing on two main issues. First, it ensures the mathematical convergence of the algorithms by maintaining the coherence between the computation of the direction of the reflected rays and the computation of the contribution of the sources to a given point in the environment. Second, the engine works directly in the frequency domain. This allows for the implementation of frequency-dependent phenomena, from surface impedance and reflections to frequency-dependent source directivity patterns. We present a comparative study of the proposed ray tracing engine with the state of the art, emphasizing properties like realism, coherence and convergence.
Effects of multiple directional sources on quantitative and qualitative analyses of concert hall acoustics
Authors: Kwon Youngmin , Siebein Gary W. , Gold Martin A.
Published: May 2008

The “orchestral impulse reponse” measurement technique using multiple directional sources and its effects on quantitative analysis of concert hall acoustics were discussed earlier [Kwon and Siebein, J. Acoust. Soc. Am. 120, 3263(A) (2006)]. An array with 16 directional loudspeakers approximating overall sound radiation patterns of each instrumental group of an orchestra was incorporated for room acoustical measurements and analyses. As a continuous study, this paper discusses qualitative assessments of concert hall acoustics over room subjective parameters including reverberance, clarity, warmth, spaciousness, envelopment, etc. The music signals binaurally recorded in a performance hall with the same source array were evaluated by means of subjective listening tests in comparison to those recorded with the single omni-directional source (dodec). The results showed that some perceived differences are present between the array with multiple directional sources and the one with a single omni-directional source. In the main orchestra seating, in particular, reverberance and clarity are perceived more but warmth is perceived less when compared to the recordings through the single omni-source. The results will be further discussed in conjunction with their quantitative measures resulted from the above measurement technique.
Room acoustics measurements with an approximately spherical source of 120 drivers
Authors: Schwenke Roger , Zotter Franz , Wessel David , Schmeder Andrew
Published: May 2008

An approximately spherical source of 120 individually controlled drivers is used to perform impulse response measurements in a room with a 1.4 s reverberation time and a distinct echo. The signal to the drivers is processed to produce both omni-directional and unidirectional patterns. The omni-directional pattern is compared with measurements made with a traditional 12 sided source. The unidirectional patterns are measured both pointed towards and away from the listener position. Intelligibility metrics for the different directionalities and orientations are measured. The unidirectional pattern is aimed in different directions to minimally and maximally excite the distinct echo in the room, and locate it's origin.
Habitat occupation time-series of St. Lawrence belugas from passive acoustic monitoring
Authors: Roy Nathalie , Simard Yvan , Bédard Catherine , Leblanc Elisabeth
Published: May 2008

Passive acoustic monitoring (PAM) was used to generate a six-week continuous time-series of occupation of a segment of the St. Lawrence Estuary by belugas. The PAM data were acquired from a cabled hydrophone deployed at mid-depth into the 300-m deep Laurentian channel off Cap-de-Bon-Desir during summer 2003. Beluga vocalisation activity time-series was obtained from the [0.5-5.0 kHz] bandpassed PAM data that were processed to filter out noise from the heavy shipping on the nearby St. Lawrence Seaway and from occasional whale watching boats, and low-frequency traces of clicks, via adaptive spectral subtraction and image processing methods applied to the spectrogram. The remaining traces on the binary image of the spectrogram were summed up to generate a vocalisation index, which was essentially due to belugas in this region. The vocalisation index time-series was then analysed for presence of circadian rhythms and correlations with the semi-diurnal tidal cycle, currents from an acoustic Doppler current profiler and wind. Results are interpreted from the knowledge of the biological and physical oceanographic processes occurring in the monitored area.
One plus one equals one: The beluga whale (Delphinapterus leucas) produces two pulses to form its echolocation click
Authors: Lammers Marc O. , Castellote Manuel
Published: May 2008

Empirical results have shown that two sound generators exist in the nasal system of delphinids. It had been previously assumed that these function independently, with one primarily involved in pulse production and the other in the generation of tonal signals. Here we report that in the beluga whale both generators appear to be simultaneously involved in the production of the echolocation click measured in front of the animal. A study was conducted that examined the propagation of the echolocation click of a captive 12 year-old female beluga whale at 15°, 30°, 45°, 60°, 75°, and 90° off the center axis of both sides of the outgoing beam. The results reveal that at angles greater than 30° two distinct pulses are measured that cannot be attributed to multipath reflections from the surface or any structure in the tank. The two pulses are maximally separated in time at 90° off-axis and gradually converge with each 15° measurement closer to the beam center. At 30° the two pulses begin to form a single, albeit distorted pulse. The phenomenon is symmetrical on both sides of the animal. These findings shed new light on how beluga whales and perhaps other odontocetes form their echolocation pulse.
Sounds from a neonate harbour porpoise and their potential use in acoustic monitoring
Authors: Wahlberg Magnus
Published: May 2008

Harbour porpoises (Phocoena phocoena) emit ultrasonic (130 kHz) clicks with a stereotyped source parameters for echolocation and communication. Recently it was observed that the first days of living, a neonate harbour porpoise emitted contact calls of much a much lower frequency emphasis, around a few kHz. The echolocation clicks produced by the calf significantly differed in duration and band width during the first four months postpartum. The acoustic signals from harbour porpoise calves are ideal for automated detection and therefore as a tool in population studies of this species. Both hydrophone array systems towed from boats, and automated click detectors (such as T-PODs) may incorporate routines for automated detection of young calves. These findings may have a large potential for facilitating biologists in gathering important biological data from this otherwise very difficult-to-study species of marine mammals.
Two-dimensional sonar beam characteristics of single harbour porpoise (Phocoena phocoena) echolocation clicks measured with a 16 hydrophone array
Authors: Koblitz Jens C. , Wahlberg Magnus , Madsen Peter T. , Stilz Peter , Schnitzler Hans-Ulrich
Published: May 2008

For the first time, the beam structure of single harbour porpoise echolocation clicks was simultaneously measured in both the vertical and horizontal plane. Echolocation clicks of a stationed animal and free-swimming animals catching fish were recorded with a “plus-shaped” array consisting of 16 hydrophones. The -3 dB beam width in the horizontal and vertical planes is in most cases similar to what has been previously measured by Au et al. (1999). However, individual clicks are sometimes broader or narrower than what has been previously reported. This may be caused by either voluntary control of the animal's beam width, or it may be a secondary effect of variations in intensity and air content within the sound production system.
Dolphin modulation rate transfer functions resulting from exposure to frequency modulated signals
Authors: Houser Dorian S. , Finneran James J.
Published: May 2008

Frequency modulated (FM) signals are useful in audiometric studies where the test environment contributes to multipath interference and produces spatial variations in the sound pressure field. Rhythmic FM stimuli are useful in evoked potential audiometry because of the auditory steady state response (ASSR) that is created within the auditory system. Although some research on dolphin ASSRs resulting from rhythmic FM signals has been performed, relationships between modulation depth, modulation rate, and ASSR amplitude have not been fully explored. To address this, two dolphins were exposed to rhythmic FM signals (120 dB SPL and center frequency=40 kHz) and the resulting ASSR recorded. The modulation depth (peak-to-peak) and modulation rate were varied from 0.1-10% and 200-2500 Hz, respectively. A total of 512 epochs were recorded for each stimulus presentation and the averaged waveform was analyzed in the frequency domain. The amplitude peak corresponding to the modulation rate was used to create the modulation rate transfer function (MRTF). Both dolphins showed a MRTF peak at a 1 kHz modulation rate, while one dolphin showed a second peak at 500 Hz. The use of rhythmic FM signals in ASSR studies may be a useful for testing in less than ideal acoustic environments.
Blue whale calls characterization using chirplet transform
Authors: Bahoura Mohammed , Simard Yvan
Published: May 2008

The blue whale, Balaenoptera musculus, frequently produce distinctive low-frequency (<100 Hz) signature calls that propagate over large distances in deep oceans. Their efficient detection and identification under variable noise conditions in long-term recordings is a basic requirement of passive acoustic monitoring systems used for studying distributional ecology and habitat selection of these large-scale migrant animals. In North Atlantic, blue whale signature calls are the A and B infrasounds (15-20 Hz), which often occur together in AB phrases, and the audible D-call (35-120 Hz), also known as arch sound. Given the distinction of these calls by their frequency band and rate of change in frequency, the chirplet transform appears well adapted to characterize such calls. We test here this new approach from subset of vocalizations of blue whale sounds recorded in St. Lawrence Estuary. The recordings are band-pass filtered and segmented to isolate individual calls. Then, a feature vector based on the chirplet transform is extracted from each call. Finally, vector quantization (VQ) is used to classify the calls into A, B, and D vocalizations. The performance of the method is compared for various VQ code book sizes. Small code book sizes using only 3 features produced classification rates exceeding 92%.
The acoustic role of supralaryngeal air sacs
Authors: De Boer Bart
Published: May 2008

This paper investigates the acoustic effect of supralaryngeal air sacs on the range of sounds that a given vocal tract can generate. Humans do not have supralaryngeal air sacs, whereas apes (chimpanzees, orangutans and gorillas) do. It has also been found that the anatomy of the hyoid bone of Neanderthals (the Kebara hyoid) is consistent with the absence of air sacs, while that of Australopithecines (the Dikika baby) is consistent with their presence. As an important difference between humans and all other primates is that humans speak, it has been suggested that the loss of air sacs has something to do with the evolution of speech. Here an articulatory model is used to compare the acoustic properties of a humanlike vocal tract with and without a chimpanzeelike air sac. The articulatory model is based on the Mermelstein model, and the air sac is a simplified model of a side branch with the approximate size of a chimpanzee air sac. It is found that the air sac reduces the range of articulations, and decreases the average formant frequency. This would provide an explanation for the presence of air sacs in apes (size exaggeration) and their disappearance in humans (increased articulatory range).
Quantitative assessment of bone properties during defect healing in an animal defect model after augmentation with different bone graft materials using scanning acoustic microscopy
Authors: Schulz Mathias , Raum Kay , Brandt Joerg , Brehme Kay
Published: May 2008

The aim of this study was to evaluate the dynamic process of bone healing and bone remodeling in an animal defect model. A nanocrystalline hydroxyapatite in an aqueous suspension paste and mixed with either autogenous or allogenic bone was implanted. The investigation was performed using quantitative acoustic microscopy at a frequency of 50 MHz. 4-mm diameter defects were prepared on each femur at distal metaphysis in 60 white New Zealand rabbits. The animals were sacrificed after 2, 4, 6, 8, or 12 weeks. The influences on the acoustic impedance values only in the newly formed bone were analyzed by two-factor analysis of variance and post-hoc multiple comparison tests. Moreover, the kinetics of bone stiffening was evaluated by fitting the impedance data to an exponential growth model. In all treatment groups the impedance increased with healing time. Significant differences between the treatment groups were observed 4, 6, and 8 weeks after treatment (p<0.05). The experimental results agreed with the exponential growth model with coefficients of correlation (R2) between 0.6 and 0.8. Nanocrystalline hydroxyapatite paste in combination with autogenous bone was found to be superior to the other evaluated treatment strategies.
Analysis of Munk waveguide normal modes based on the Rayleigh-Schrödinger perturbation and adiabatic invariant theories
Authors: Guimarães Luiz
Published: May 2008

This work concerns to obtain accurate explicit formulas related to discrete spectrum of the Munk deepwater acoustic wave guide problem. To this end, based on the Rayleigh-Schrödinger perturbation theory, we developed analytic results related to the discrete values of the radial wave numbers as well as to the eigen pressure felds. We compare these previous results with JWKB ones. In addition, based on invariant adiabatic theory to wave equation [1,2], we tried to improve the accuracy of the JWKB calculation applying Olver's uniform asymptotic expansion (UAE) theory for the solution of the second-order differential equation with two turning points [3-5]. Comparing these three above particular frameworks, we conclude that UAE theory is accurate and it well describes the Munk wave guide normal modes. [1] L. M. Brekhovskikh and Yu. P. Lysanov, Fundamentals of Ocean Acoustics, Spinger, NY, 2001. [2] B. G. Katsnelson and V. G. Petnikov, Shallow Water Acoustics. Spinger, UK, 2002. [3] F. W. J. Olver, Asymptotics and special functions, Academic Press, London, 1974. [4] L. G. Guimarães and H. M. Nussenzveig, J. Mod. Optic., 41, 625 (1994). [5] P. C. G. de Moraes and L. G. Guimarães, JQSRT, 74 757 (2002).
Using angular dependence of multibeam echo features in seabed classification
Authors: Lubniewski Zbigniew , Chybicki Andrzej
Published: May 2008

The approach to seabed classification based on processing multibeam sonar echoes is presented. The multibeam sonars, besides their well verified and widely used applications like high resolution bathymetry measurements or underwater object imaging, are also the promising tool in seafloor identification and classification, having several advantages over conventional single beam echosounders. The proposed seabed classification method assumes calculation of a set of parameters of an echo envelope, similarly as in single beam classification. These parameters include echo energy, echo length, statistical moments of echo energy and the set of echo shape descriptors. They are extracted for each consecutive beam allowing the estimation of their dependence on seafloor incident angle. The characteristic features of this dependence are described quantitatively and constitute the input information for an automatic supervised seabed classifier. The results of the simple classification procedure applied for multibeam data records acquired from several bottom types in Gdańsk Bay region are presented and discussed.
Applications of compression techniques for reducing the size of multibeam sonar records
Authors: Chybicki Andrzej , Moszynski Marek
Published: May 2008

High efficiency of multibeam sonar system (MBS) hardware due to operational requirements (i.e., high frequency, high ping rate, and high resolution of collected data) results in very large volumes of datasets stored on local hard drives of operator's station. In this context, the process of archiving of such warehouse of data collected in previous surveys becomes crucial problem. The paper investigates various lossy and lossless compression methods that can be applied to multibeam sonar data to reduce the size of acquired files without loosing relevant information. The specific character of MBS data allows applying various signal, image, and video compression methods to achieve better results than when using standard ones. Various techniques of reordering the data were analysed to achieve best possible compression ratio.
High power sources for ultrasound thermal therapy and shock wave lithotripsy
Authors: Owen Neil , Cathignol Dominique , Melodelima David , Birer Alain , Chapelon Jean Yves , Lafon Cyril
Published: May 2008

We present a summary of Inserm's experience with high power sources, which are necessary for ultrasound thermal therapy and lithotripsy. Moreover, generating high intensity pseudo-continuous waveforms or high pressure pulses imposes different constraints on the transducer materials, specifically heat and mechanical stress. For thermal therapy, miniature piezoceramic transducers were used for interstitial, intratumoral, and endoluminal applicators. These probes operated at surface intensities up to 50 W/cm2 and generated elementary lesions in vivo within tens of seconds. Piezocomposite transducers were developed for large-aperture, highly-focused beams used in extracorporeal or intraoperative treatments. Focal intensities were 1000 W/cm2 or higher and up to 256 elements were utilized. Miniaturized piezocomposite transducers are currently being developed for dual-mode imaging and therapy. For lithotripsy, piezoelectric shock wave generators were developed as alternatives to electrohydraulic or electromagnetic generators. Using piezocomposite materials and a novel prestraining method increased transducer surface pressure compared to a multielement piezoceramic design, and therefore halved the aperture diameter. In in vitro tests, plaster kidney stone models were comminuted with ∼200 shock waves, a number comparable to values published for electrohydraulic generators, the current “gold” standard. This work contributes to the advancement of transducer performance in therapeutic ultrasound. [Supported by Inserm Post-doctoral Fellowship.]
An eight-element annular array for image-guided high intensity focused ultrasound therapy
Authors: Kaczkowski Peter , Cunitz Bryan , Keilman George
Published: May 2008

The investigation of high intensity focused ultrasound (HIFU) as a tool for noninvasive thermally ablative therapy has required deeper understanding of the relative roles of nonlinear mechanisms involved in heat deposition. Attempts at quantifying the dose response to particular exposure conditions in vitro are complicated by the interplay of several mechanisms. These include microbubble cavitation, nonlinear acoustic propagation and attenuation, dependence of tissue parameters on temperature and temperature history, and formation and evolution of vapor bubbles due to boiling. One immediately evident consequence of such effects is distortion of coagulative lesion shape and size, colloquially evolving from “cigars” to “tadpoles”. Developing a quantitative understanding of the relative roles of relevant nonlinear mechanisms is not straightforward, yet is desirable for design of algorithms for therapy planning and real time monitoring using ultrasound. A historical perspective of research toward this end will be presented along with a recommendation for suitable terminology for the various physical acoustic regimes encountered in HIFU therapy. [Work supported by Army MRMC, NIH DK43881, NSBRI SMS00402, and RFBR.]
Dual-frequency driving transducer for ultrasonic echography
Authors: Akiyama Iwaki , Yoshizumi Natsuki , Saito Shigemi , Koyama Daisuke , Nakamura Kentarou
Published: May 2008

We propose a novel ultrasonic imaging technique by transmitting ultrasonic pulse of dual-frequency and receiving multifrequency echoes from the biological tissues. When the ultrasonic pulse of two frequencies is transmitted from a transducer, the secondary waves are generated during the nonlinear propagation through the biological media. A choice of f0 and 4f0 as the dual-frequency results in the generation of 2f0, 3f0, and 5f0 components as the secondary waves. Multifrequency echoes are capable of improving the image quality by reducing the speckle noise. We have developed the following annular type transducer. The PZT disk of 7 mm in diameter is coaxially arranged in the PZT ring of 9 mm in inner diameter and 17 mm in outer diameter. The ring and circular transducers transmit the pulses of 2 and 8 MHz, respectively. It was confirmed that this transducer formed the ultrasonic beams of 4, 6, and 10 MHz as well as the beams of 2 and 8 MHz in degassed water. Then the experiments of imaging the agar-gel phantom and pork meat were carried out by mechanical scanning. As a result, we also confirmed the improvement of image quality by reducing the speckle noise.
Micromachined linear array with 100 MHz center frequency
Authors: Weiss Eike C. , Jakob Anette , Tretbar Steffen H. , Haberer Werner , Knoll Thorsten , Bauerfeld Frank , Herrmann Joerg , Lemor Robert M.
Published: May 2008

High-frequency ultrasound systems based on single element transducers in the frequency range of 50-120 MHz and mechanical scanning of the transducer. Linear arrays with electrical scanning can be used to increase the speed of scanning and reduce the size of the transducers. We present a linear array combined with multiplexer and single channel electronics. Working at 100 MHz, lateral resolution better than 100 μm is possible with an aperture of 1 mm2. The 100 MHz array is based on silicon micro machining with a ZnO membrane as active material. The most important steps are the deposition of a 26 μm-thick ZnO thin film by magnetron sputtering and the anisotropic etching of the backside of the silicon wafer to fabricate the ZnO membrane. The individual elements of the transducer are defined by patterning a gold electrode with the desired array structure via photolithography and subsequently wet etching. Results from 32 element arrays with an 8 element 500 by 500 μm aperture agree well with numerical simulations and the shifting of the aperture works as well. Due to the cost-effectiveness of the process, a large number of applications have come now into reach for high-frequency ultrasound imaging.
Assessment of cortical bone density and anisotropy in human femur using ultrasound and x-ray
Authors: Cretin Dorian , Suetoshi Ryouichi , Uodome Atsushi , Ogawa Shinji , Miyabe Sakaya , Nakano Takayoshi
Published: May 2008

The purpose of this research is to investigate the contribution of the intrinsic properties of human bone to the ultrasound velocities in the axial, radial, and tangential directions. Samples of cortical bone were cut from 19 human medial femurs and polished to a rectangular parallelepiped shape. The orientation of apatite crystallites was assessed by microbeam x-ray diffraction, the density with a densitometer using the Archimedes' principle. Bone mineral density (BMD) was also measured with peripheral quantitative computed tomography (pQCT) and dual-x-ray absorptiometry (DXA). The speed of sound (SOS) for each three directions was measured with 3 MHz ultrasonic broadband transducers. Radial and tangential SOS demonstrated a strong correlation with density (R=0.83,p<0.0001 and R=0.85,p<0.0001, respectively). In the axial direction, the correlation between density and SOS was moderate (R=0.59). However, a significant correlation was found by using density and apatite orientation of c-axis in a multiple regression analysis (R=0.85,p<0.001). Axial SOS can be explained by contributions of both density and crystal orientation.
Experimental determination of Young modulus and Poisson ratio in cortical bone tissue using high resolution scanning acoustic microscopy and nanoindentation
Authors: Rupin Fabienne , Saied Amena , Dalmas Davy , Peyrin Françoise , Haupert Sylvain , Barthel Etienne , Boivin Georges , Laugier Pascal
Published: May 2008

Nanoindentation allows measurements of local mechanical properties of bone tissue. Scanning acoustic microscopy (SAM) provides images related to bone density and elasticity. In both techniques, the estimation of Young modulus (E) relies on the accuracy of Poisson's ratio value (σ). In cortical bone, σ varies between 0.15 and 0.45 but, is classically set to 0.3, resulting in an approximate value of E. This study describes a new method combining SAM and nanoindentation techniques to locally evaluate σ in human femoral cortex. A 200 MHz SAM-based acoustic impedance (8 μm lateral resolution) was combined with synchrotron microtomography (to provide local bone mineral density) to map the distribution of near surface elastic modulus. Whereas, nanoindentation modulus was calculated on several osseous regions. Assuming the equalization rule, the intersection of both modulus curves versus σ permits to accurately derive σ. The method was tested on aluminium, PMMA and polycarbonate samples of known σ and provided experimental σ values with a precision better than 3%. In bone, σ was 0.42±0.01 corresponding to E=20±1 GPa. Our preliminary results indicate that combination of high-resolution SAM and nanoindentation may be relevant to accurately determine both Poisson ratio and Young modulus of bone tissue.
1 kHz sound stimulates nitric oxide and prostaglandin E2 production by rat mesenchymal stem cells
Authors: Bossis Dorothée , Padilla Frederic , David Bertrand , Petite Hervé , Laugier Pascal
Published: May 2008

Pulsed ultrasound has become a common therapy for delayed unions and non unions. Currently available clinical devices use modulated (1 kHz) 1.5 MHz ultrasound stimulation that produces a 1 kHz radiation force vibration. It was hypothesized that this radiation force is responsible for the stimulatory effect on bone formation. Therefore, we have investigated the effect of 1 kHz stimulation in rat mesenchymal stem cells (MSCs) by measuring the production of on nitric oxide (NO) and prostaglandin E2 (PGE2). Continuous wave 1 kHz low power sound was applied to cultured rat MSCs for 20 min. NO concentration was determined by amperometry and PGE2 was assayed by ELISA in the supernatant. The stimulation produced a significant increase in both NO and PGE2 concentration compared to controls. We conclude that rat MSCs respond to the mechanical stress produced by 1 kHz continuous wave as evidenced by the increase in NO and PGE2 production. This study provides evidence for the action of 1 kHz stimulation on bone cells.
Comparative study of vibro-acoustography and B-mode ultrasound in prostate imaging
Authors: Alizad Azra , Mitri Farid , Davis Brian , Greenleaf James , Fatemi Mostafa
Published: May 2008

Vibro-acoustography (VA) is an imaging modality that uses the radiation force of ultrasound to vibrate tissue at a low frequency and records the resulting acoustic field to produce an image that is represents object characteristics at both ultrasound as well as low (audio) frequencies. Currently, B-mode ultrasound is used for prostate imaging. This imaging method has some limitations, including the speckle noise, which limit its ability in detection of lesions and calcifications. The purpose of this study is to explore the potentials of VA for prostate imaging. VA, B-mode ultrasound, and radiography were performed on 12 excised human prostate samples and the resulting images were compared. VA system parameters were, center frequency 3 MHz, Δf=50 kHz, image area 5×5 cm, pixel size 0.2×0.2 mm. Images evaluated in terms of visibility of anatomical and pathological structures and contrast. Results showed that prostate anatomical structures, mass lesions, and calcifications were visible in the VA images taken at different depths, and VA image quality was superior to B-mode. VA images exhibited significant contrast between the central and peripheral zones with enhanced borders. It is concluded that, with further development, VA may become suitable modality for in prostate imaging.
Ultrasound-enhanced latex immunoassay of pathogens in water
Authors: Bavli Danny , Barenholz Yechezkel , Emanuel Noam , Ponomarev Victor , Priev Aba
Published: May 2008

Real-time knowledge of contaminants in water is an essential component of any potable water security system. Latex immunoassay is the basic technique in rapid identification of pathogens. We used acoustic radiation to accelerate the latex immunoassay and to bring about separation between free and bound antigen (rotavirus SA-11) in less than one minute. The ultrasonic cylindrical standing-wave device of NDT Instruments, UltraAssay 101, creates areas of maximum and minimum potential energy (nodes). Acoustic radiation forces acting on the pathogens drive them directly to the central node. In this manner, antibody-antigen complexes accumulate in the nodes in 40-60 sec. The nonbound antibodies are washed out of the separation area by the buffer flow. The forces responsible for separation of particles in the UltraAssay 101 depend on the frequency of the standing-wave resonator and on the density, compressibility and size of the immune complexes. Additionally, UltraAssay 101 is able to directly monitor water salinity, turbidity and specific gravity.
Radiation force on spheres in acoustic beams and related aspects of scattering
Authors: Marston Philip L. , Thiessen David B.
Published: May 2008

The close connection between the acoustic radiation force on objects in fluids and the angular distribution of the farfield scattering is especially useful in cases where dissipative effects are weak in the surrounding fluid. This connection also applies to objects illuminated by acoustic beams and has been used to extend the analysis of scattering by spheres in Bessel beams [P. L. Marston, J. Acoust. Soc. Am. 121, 753-757 (2007); 122, 247-252 (2007)] to the evaluation of the radiation force on spheres [P. L. Marston, J. Acoust. Soc. Am. 120, 3518-3524 (2006); 122, 3162-3165 (2007)]. The quantitative predictions (which include situations of negative radiation force) have been verified by nearfield analysis of the radiation force using the finite element method. We have also examined the radiation force on a sphere for a special case of co-propagating Bessel beams having unequal beam parameters. The scattering of a higher order Bessel beam by a sphere placed on the axis has also been analyzed. The backscattering in that case vanishes in agreement with prior predictions [B. T. Hefner and P. L. Marston, J. Acoust. Soc. Am. 106, 3313-3316 (1999)] for a general class of helicoidal acoustic beams. [Supported by NASA and ONR.]
Biomedical applications of acoustic radiation force based on somatosensory reception
Authors: Gavrilov Leonid R. , Hand Jeffrey W. , Tsirulnikov Efim M.
Published: May 2008

We have previously shown that short pulses of focused ultrasound may be used to stimulate locally receptor neural structures and thereby induce sensations that humans can perceive through the skin (for example tactile, warmth and cold, tickling, pain, etc.). Furthermore, ultrasound modulated by sound signals (tone, speech, music, etc.) can induce sound sensations corresponding to the nature of the modulation in persons with normal hearing. The mechanism underlying these effects that have been used in clinical diagnostic practice is related to the radiation force. We also showed recently that the phenomenon of the radiation force could be used in perspective robotic systems, sensors, and automated control systems, based on the use of tactile sensations in the human-machine interface, as well as in devices that may allow blind and visually impaired persons to perceive textual information presented on a tactile display. The research was supported by INTAS (05-1000008-7841) and RFBR (06-02-16079).
In vivo feasibility of local harmonic motion imaging and its use for thermal surgery control
Authors: Hynynen Kullervo , Curiel Laura , Chopra Rajiv
Published: May 2008

A local harmonic motion can be generated within the tissues by the periodic induction of radiation force using a focused ultrasound (FUS) transducer. Tissue motion can then be tracked by collecting rf signals during the excitation using a separate transducer. Finally, displacement estimates can be obtained by cross-correlating the collected rf signals. The characteristics of the induced LHM depend on the local elastic properties of the tissues making it an attractive tool for imaging and therapy control applications. LHM measurements have been obtained in vivo on rabbit muscle and it was observed that the amplitude of the motion was significantly reduced after coagulation. LHM was successfully used to spatially detect the presence of the coagulation lesions within the tissues as a drop in LHM amplitude. It was also possible to detect the location of an implanted VX2 tumor when a spatial scan was performed as the LHM amplitude was lower inside the tumor because of an increased stiffness. Measurements of LHM during tissue heating using FUS reflected the changes in stiffness and revealed the apparition of coagulation showing the potential of these measurements as an alternative control for the FUS exposure. [Work supported by NIH Grant R33 CA102884 and the Canadian Research Chair Program.]
Impulsive acoustic radiation force: imaging approaches and clinical applications
Authors: Nightingale Kathryn , Palmeri Mark , Zhai Liang , Frinkley Kristin , Wang Michael , Dahl Jeremy , Fahey Brian , Hsu Stephen , Bradway David , Trahey Gregg
Published: May 2008

Focused acoustic radiation force can be used to locally mechanically excite tissue, and the tissue response can be monitored with conventional ultrasonic displacement estimation methods. Many groups are currently exploring the potential for radiation force based methods to derive information about tissue stiffness associated with different pathologies. These techniques can be implemented on a modified diagnostic ultrasound scanner, using the same transducer for both generating the radiation force excitation and monitoring the tissue response. Multiple locations within an imaging field of view can be interrogated sequentially, by electronically controlling the push and track apertures and beam locations. A variety of data processing and imaging approaches are under investigation. Images are generated of the tissue displacement magnitude within the region of excitation at a given time after radiation force application. These images portray relative differences in tissue stiffness, and provide interesting structural information that is well correlated with, and often exhibits improved contrast over, matched B-mode images. Methods for quantifying tissue stiffness through monitoring shear wave propagation, as originally proposed by Sarvazyan, are also under investigation. Results from ongoing clinical studies using these methods in a variety of organs (e.g., liver, prostate, breast, and heart) will be presented.
Ultrasonic imaging of displacements inside objects induced by continuously applied fluctuating acoustic radiation forces
Authors: Hasegawa Hideyuki , Odagiri Yoshitaka , Kanai Hiroshi
Published: May 2008

Recently, many studies are conducted to measure the response of soft tissue to applied ultrasonic acoustic radiation force. However, the change in position of a target is dominantly induced by a radiation force applied from only one direction, particularly when the target is much harder than surrounding medium. In this case, elasticity of the target cannot be evaluated because the change in position does not relate to target's elasticity. In this study, 1-MHz continuous-wave ultrasound whose envelope fluctuated at 5 Hz was used to apply the radiation force fluctuating at 5 Hz. By applying two radiation forces from two opposite horizontal directions, the object would be effectively deformed (compressed) in the horizontal direction and vertically expanded due to its incompressibility. Resultant vertical displacements were measured by ultrasonic pulses at 22 MHz in center frequency which can be easily separated from 1-MHz ultrasound by filtering. In in vitro experiments using chicken muscle and porcine liver, displacements at 5 Hz were clearly imaged. Amplitudes of displacements in liver are similar to those in muscle, whereas applied radiation force was one-fifth. Furthermore, shear wave propagating in liver was clearly visualized because liver was much softer than muscle, i.e., the wavelength was much shorter.
Assessment of tissue viscoelasticity using acoustically interrogated laser-induced microbubble
Authors: Emelianov Stanislav Y. , Aglyamov Salavat R. , Karpiouk Andrei B. , Ilinskii Yurii A. , Zabolostkaya Evgenia A.
Published: May 2008

Lasers are used in many biomedical and clinical applications, ranging from diagnosis to therapy. In eye microsurgery, for example, a pulsed laser beam produces a localized surgical effect through the formation of a cavitation microbubble as a result of tissue photodisruption occurring in the focal zone. However, to insure successful presurgical planning, surgical procedure, and postoperative stages of pathology treatment, the mechanical properties of the tissue must be analyzed before selective laser intervention. Since microbubbles are already produced during laser surgery, we have developed an integrated approach utilizing these laser-induced microbubbles as reporters of tissue viscoelasticity. Specifically, we have derived a general model of gas bubble dynamics in viscoelastic media to describe both translation and oscillations of the microbubble exposed to the acoustic radiation force. Furthermore, an ultrasound method based on temporal measurement of passive acoustic emission from cavity during laser-tissue interaction and simultaneous active pulse-echo ultrasound probing of the cavitation bubble was developed to detect and characterize the laser-induced microbubbles. The results of our theoretical, numerical, and experimental studies demonstrate that measurements of gas bubble behavior exposed to acoustic radiation force can be used to assess the mechanical properties of the surrounding tissue.
The need to integrate speech acoustics course work across the speech-language pathology curriculum
Authors: Siren Kathleen
Published: May 2008

The profession of speech-language pathology faces two critical challenges: (1) the lack of sufficient evidence-based practice due to limited clinical research in the field and (2) the dramatic decline in recent years in the number of students pursuing PhDs. Although speech acoustics courses are a part of most undergraduate programs in speech-language pathology, these courses are often disassociated from students' additional undergraduate and graduate course work and clinical training. These isolated speech science courses may inadequately prepare speech-language pathology students for future research-based course work and clinical practice. This paper reports results of a survey of 140 former undergraduate students who took a speech acoustics course between 1994 and 2003. The survey asks students about additional speech acoustics course work, related research experience, and use of speech science information in clinical practice. The majority of students surveyed report that speech acoustics information is largely isolated in one undergraduate course. This paper concludes that programs must consider better harmonizing speech science course work with other undergraduate and graduate course work and clinical training to meet the current research related challenges to the profession.
Noise induced hearing loss amongst classical music students - An audiometry study of students of the Royal Academy of Music
Authors: Zepidou Georgia , Dance Stephen , Morant Salvador
Published: May 2008

Under the new UK guidance for Control of Noise at Work, entertainment noise now has to be considered for all employees. Health surveillance has been undertaken as part of the induction for all 1st year students studying at the Royal Academy of Music in London, as of September 2007. Seminars were arranged and details of the audiometric tests given prior to the health surveillance, so that only valid data was collected. A total of 350 students were asked to fill out questionnaires on their particular habits. Analysis of the audiograms showed double the incidence of health surveillance warning levels of hearing loss amongst men compared to women, although both had significantly better hearing than general population for their age. When early signs of noise induced hearing loss were considered, a loss of more than 20 dB at any high frequency, was indicated for more than half of the brass musicians.
Why practice scales? Details of fingering transitions in flute playing
Authors: Almeida André , Chow Renee , Smith John
Published: May 2008

Mastering a wind instrument requires not only expert blowing and embouchure, but also many hours of practice of exercises that improve the fingering speed, regularity and coordination. Many note transitions involve the motion of several fingers, often in opposite directions. The order of finger movement can sometimes affect the transitions between notes and produce short, spurious notes between the original and destination notes. We adapted a transverse flute for real time measurement (with a resolution of 3 ms) of all key positions using reflected light sensors. Beginner and advanced players were asked to perform a phrase including multifinger transitions. The detailed motion, average speed and intervals between finger motion were analysed. The comparison among players is not surprising: an experienced player was found to have more regular time intervals between fingers moving in a same direction (within 10 ms) than an amateur (within 25 ms). Contrary fingering motions are slightly less regular (15 ms for an experienced player against 50 ms for an amateur), but still unperceptible to the ear in the case of the experienced musician. A range of details will be reported, for instance the influence of scale exercises.