bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between stimulus and compression type in precedence situations with hearing aids
Authors: Seeber Bernhard U. , Eiler Cheryl , Kalluri Sridhar , Hafter Ervin R. , Edwards Brent
Published: May 2008

Multiband compression in hearing aids has the potential to interfere with binaural perception by altering binaural cues. We compared binaural precedence in patients fitted with compression hearing aids or linear hearing aids and tested one month later with a variety of stimuli. In an open field environment simulated in an anechoic chamber, subjects localized the direction of a leading sound accompanied by a lagging copy played from a different direction. Precedence, defined by a strong influence of the first sound, was found in 6/7 of the subjects when the stimulus was a sentence, but in only 4/7 when it was a high-pass or a wideband burst of noise. The fact that increasing the noise-bandwidth to include low frequencies did not produce precedence in the two patients who had shown it with a sentence may indicate a need for them to accumulate information through the successive pseudo onsets in the speech-envelope. The choice of amplification, compressive or linear, did not significantly affect precedence for any sound, except for one subject who showed weak influence of compression with the high-pass noise. We conclude that although compression might alter interaural level cues, for most, especially with long sounds, localization dominance appears unimpaired.
Time domain identification of loads on plate-like structures using an array of acoustic velocity sensors
Authors: Leclere Quentin , Pezerat Charles
Published: May 2008

The FAT (Force Analysis Technique) method has been developped to identify loads on beams or plates from the knowledge of their flexural displacements. The method is based on a local discretisation of the differential operator of the studied structure : all derivatives of the displacement field are assessed at a given point from a finite difference scheme. The estimation of the operator gives as an output the value of the force distribution. Up to now, applications of the FAT method have been made in the frequency domain, scanning the studied structure with accelerometers or with a laser vibrometer, and using phase references to get the phase relation between different points. The aim of the present study is to show that the FAT method allows to identify loads in the time domain. This operation requires the simultaneous measurement of at least 13 points on the plate, that can be realized without contact using an array of acoustic velocity sensors in the very near field of the plate. The method has been applied on a plate excited by an acoustic diffuse field. The identified force distribution is compared to the parietal acoustic pressure measured in the reverberant room.
An autocorrelation model of bat sonar
Authors: Wiegrebe Lutz
Published: May 2008

Their sonar system allows echolocating bats to navigate with high skill through a complex, three-dimensional environment at high speed and low light. The auditory analysis of the echoes of their ultrasonic sounds requires a detailed comparison of the emission and echoes. Here an auditory model of bat sonar is introduced and evaluated against a set of psychophysical phantom-target, echo-acoustic experiments. The model consists of a relatively detailed simulation of auditory peripheral processing in the bat, Phyllostomus discolor, followed by a functional module consisting of a strobed, normalised, autocorrelation in each frequency channel. The model output is accumulated in a sonar image buffer. The model evaluation is based on the comparison of the image-buffer contents generated in individually simulated psychophysical trials. The model provides reasonably good predictions for both temporal and spectral behavioural sonar processing in terms of sonar delay, roughness, and phase sensitivity and in terms of sensitivity to the temporal separations in two-front targets and the classification of spectrally divergent phantom targets.
Absolute target range and target range profile in separate computational compartments: Synthetic aperture echolocation
Authors: Simmons James A.
Published: May 2008

Echolocating big brown bats emit wideband (20-100 kHz) FM sounds and perceive target range from echo delay with an accuracy determined by echo relative bandwidth (Q). They distinguish among target shapes by echo spectra, but they perceive shape in terms of distances to different parts (glints), or the target's range profile. Shape resolution based on glint delay differences extracted from target interference spectra is in fractions of millimeters. The bat's flight velocity is about 5 m/s, so that echo delay changes continuously during production of broadcasts and then again during reception of echoes, smearing and displacing delay estimates for target ranging by several hundred microseconds. Previous workers have identified a particular distance at which smearing is minimal, but it is not known whether this "distance of focus" has significance for the bat. However, perception of target shape is based on a spectral representation that is only slightly distorted by the bat's motion, and it is kept in separate computational path from absolute delay until after absolute delay is determined, whereupon it is attached to absolute delay to place the target's image in an approximate spatial position. The bat's system achieves synthetic aperture imaging of shape while avoiding motion-related blurring.
Echolocation-like pulse emission for communication by Japanese horseshoe bats, Rhinolophus ferrumequinum nippon
Authors: Riquimaroux Hiroshi , Shimazawa Ryota , Hiryu Shizuko
Published: May 2008

It has been reported that the bats communicate with conspecifics by various types of vocalizations, which are different from echolocation pulses. However, we have found pulses used for communication, which were emitted when a bat walked to another individual, appeared to be very similar to those for echolocation. Data have shown two evidences. First, the bats never approached another one without emitting pulses. Second, the bats emitted echolocation-like pulses whose CF2 frequency sequentially changed during the approaching behavior. Such pulses were never emitted by an isolated bat. The changes in CF2 frequency were clearly different from Doppler-shift compensation. If this frequency shift was caused by Doppler-shift compensation, the bat should be moving as fast as 1-5 m/s in the cage. Thus, we suggest that these CF2 frequency shifts may play an important role for communication during the approaching behavior to a conspecific animal. [The research supported by a grant to RCAST at Doshisha Univ. from MEXT and by the Innovative Cluster Creation Project promoted by MEXT.]
Passive acoustic localization techniques of Eastern Pacific grey whales
Authors: Wladichuk Jennifer L. , Megill William M. , Blondel Philippe
Published: May 2008

Eastern Pacific grey whales (Eschrichtius robustus) apparently do not actively echolocate, yet still they thrive in shallow water environments where visibility is much reduced. Along their migration route and in their feeding grounds these whales are exposed to high levels of ambient noise, highlyturbid waters and many underwater obstacles. To test possible passive acoustic localization mechanisms (e.g. Acoustic Daylight Imaging and Passive Synthetic Aperture), we made extensive acoustic measurements during comprehensive field studies of these whales on their summer feeding grounds in British Columbia (Canada). In combination with visual observations of the whales and their behaviours, we investigated the acoustical sources available to the whales when navigating within a feeding bay. First, we measured ambient noise levels to construct the acoustic landscape around the whales. Second, we investigated how sound is altered when objects such as kelp beds and rocks are present. We also measured acoustic changes induced by direct, controlled modifications of the near-shore environment. The aim of this research is to understand how grey whales might be finding their way around, and what impact, if any, increased levels of ambient noise might have on the whales' ability to find food and navigate within the feeding grounds.
The effects of noise emanating from an adjoining architectural space on beluga whale audition in an aquarium exhibit
Authors: Starke Katie , Scheifele Peter
Published: May 2008

Aquaria must have regulations regarding the intensity levels of anthropogenic noise that make their way into their captive belugas' tank, thus affecting the animals' ability to hear and vocalize naturally. My research focuses on the sound transmission across the acrylic and cement boundary that separates the beluga tank from the ballroom in the Georgia Aquarium. This ballroom hosts many social events which are often accompanied by high levels of noise that cross the barrier into the animal enclosure. I focus on the intensity range of 90-100dBA and experiment with a variety of frequencies, specifically those that are included in the range of beluga hearing. Though the data will be specific to the Georgia Aquarium, the results will apply to all aquaria that keep beluga whales, as high intensity sound will always travel through the exhibit boundaries and affect the animals living on the other side.
High-frequency broadband acoustic scattering for investigating double- diffusive convection
Authors: Ross Tetjana , Lavery Andone
Published: May 2008

Polar regions, with their supercooled and relatively fresh surface water, are highly susceptible to the diffusive regime of double-diffusive convection (DDDC). The fluxes associated with DDDC can play a significant role in their heat/buoyancy budgets. The use of high-frequency acoustics as a tool to map the extent and evolution of DDDC in the ocean is explored through a series of laboratory 200-300 kHz broadband acoustic backscattering measurements. Pulse compression signal processing allows centimeter-scale interface thicknesses to be rapidly and remotely measured, and the evolution, and ultimate merging, of multiple centimeter-scale interfaces to be observed. Combining the acoustically measured interface thicknesses with knowledge of the relatively-constant temperatures within the surrounding layers allows the estimation of DDDC fluxes. Thus, broadband acoustics offers a rapid and remote method to infer fluxes, without the need for time-consuming microstructure measurements, suggesting that this technique could benefit field studies of DDDC. Using simple models to extrapolate to the thermohaline steps typically found associated with DDDC in polar regions, diffusive-convection interfaces are predicted to scatter at measurable levels in many areas. Narrowband (120 and 200 kHz) acoustic backscattering observations of two scattering layers in the Western Antarctic Peninsula support this prediction.
Extracting Green's functions from noise correlation of SW06 data
Authors: Brooks Laura , Gerstoft Peter
Published: May 2008

Ambient noise was recorded on an L-shaped array during the SW06 (Shallow Water 2006) sea trials. The data were cross-correlated in order to approximate the Green's function, and subsequently the acoustic travel time, between hydrophone pairs. Examination of the individual noise spectra and their mutual coherence revealed that the coherently propagating noise is dominated by frequencies less than 100 Hz. Both time and frequency domain preprocessing techniques, and their effect upon the resulting correlation, were investigated. Times corresponding to the envelope peak of the noise cross-correlation time-derivative are in agreement with both the expected direct, and surface reflected, inter-hydrophone travel times.
Acceleration of ultrasonic tissue heating by microbubble agent
Authors: Umemura Shin-Ichiro , Yoshizawa Shin , Sasaki Kazuaki , Kawabata Ken-Ichi
Published: May 2008

Ultrasound in the existence of microbubbles, whether they have been generated by acoustic cavitation or administered into the body, is known to induce bioeffects normally through mechanical or sonochemical mechanisms. Recently, it is reported that ultrasonic tissue heating can be accelerated several times by an administered microbubble agent. A microbubble, subjected to ultrasonic pressurein the frequency range of its resonanance converts the acoustic energy to heat through its volume oscillation. The acoustic power converted to heat by a microbubble through viscous heating was numerically calculated, and it was predicted that tissue ultrasonic absorption would be doubled if a microbubble agent is delivered to the tissue at a concentration in the order of 100 microbubbles /mg. Exteriorized murine kidneys were exposed to focused ultrasound at 3.2 MHz in degassed saline and the tissue temperature change was measured. Optison at a dose of 0.2 ml /kg multiplied the temperature elevation induced by ultrasonic exposure by several times. In order to use this effect to treat a deep-seated tumor, microbubbles should be somehow delivered to the tumor selectively. A novel method of selective delivery, in which nano liquid particles are administered and converted into microbubbles by ultrasonic stimulation, will also be discussed.
Ultrasound contrast agents pushing drug delivery: high speed optical observations
Authors: Van Wamel Annemieke , Kooiman Klazina , De Jong Nico
Published: May 2008

Ultrasound-activated-microbubbles can cause transient non-lethal sonoporation of cells. Studies of influx of cell-membrane impermeable-dye, genetic materials, and nanoparticles have confirmed that the action of ultrasound-microbubbles on the cell-membrane is to alter both the cell-permeability. The sonoporation action of ultrasound-contrast-agent on cells lies in the fact that microbubbles oscillate while irradiated with ultrasound resulting in a mechanical-deformation of the cells. Oscillation microbubbles nearby cells have been optically recorded using a microscope and a high-speed camera. This camera is able to record the MHz oscillation microbubbles and therefore the interaction between oscillation microbubbles and cells. Micro-mechanical forces generated by the oscillating microbubble may also be used to locally 'push' the drugs into the cells. Ultrasound-activated-microbubbles are able to transiently increase the vascular-endothelial-layer permeability. These features may be used for future ultrasound-guided drug-delivery-systems. Next to increasing the drugs internalization, microbubbles can also be used as drug/particle carrier. Drug-loaded contrast-agents can be intentionally ruptured by diagnostic ultrasound. Using microbubbles to carry drugs to targets sites and rupturing the microbubbles by localized ultrasound energy, will result in a high local concentration of drugs. High-speed-optical-recordings of ultrasound-contrast-agent induced cell and vascular-endothelial-layer permeability will be demonstrated. Furthermore, recordings of ultrasound-controlled drug-delivery using pay-loaded ultrasound-contrast-agents will be shown.
Echogenic liposomes for molecular targeted therapeutic delivery
Authors: McPherson David D. , Huang Shaoling , Holland Christy K.
Published: May 2008

Our group has developed targeted echogenic liposomes (ELIP) that can entrap therapeutics and release them at the target site. A key therapeutic is t-PA (tissue plasminogen activator). We have demonstrated entrapment and release following ultrasound application with t-PA effect on clot dissolution. We have demonstrated that t-PA can act as a targeting agent. Thus this drug can be both a targeting agent and a lytic agent minimizing the development of complicated formulations required for targeting and lysis. We have entrapped glitazones and demonstrated release following ultrasound application with drug effect by suppressing vascular hyperplasia. We have demonstrated that ultrasound with our ELIP can enhance delivery of agents into all areas of the atheroma, including the intima, media, the loose and dense adventitia. Heretofore these regions close to the arterial media have been impenetrable using standard intravenous drug therapy. These projects are helping to develop our echogenic immunoliposomes to; optimize targeted contrast delivery into vascular beds that are poorly penetrable by standard imaging agents; and optimize local release and concentration of therapeutics at the site of interest. This will ultimately help to direct therapeutic delivery, increase local effect, while minimizing the systemic effects of drugs and genes.
Comparison of Spectral and Temporal Criteria for Inertial Cavitation Collapse
Authors: Santin Mathieu , Haak Alexander , Bridal Lori , O'Brien, Jr. William D.
Published: May 2008

Dilute solutions of Optison and Definity were studied using a passive cavitation detector (PCD) with a 2.8-MHz transmitter and 13-MHz receiver. The dilution was such that each received signal should, on average, arise from a single microbubble. Several hundred microbubble responses were acquired at each of three rarefactional pressures (1.6+/-0.2, 2.0+/0.2 and 2.4+/-0.2 MPa). Each microbubble response was grouped with signals presenting post-excitation emissions (100% Inertial Cavitation-Collapse) or those with no evidence of post-excitation emission (0% IC-Collapse). For each incident pressure, we compared discrimination of 100% and 0% IC-Collapse groups with peak-voltage, broadband noise (12-17.6 MHz) and power at the fundamental, 2nd, 3rd, and 4th harmonic peaks. In addition to increased peak-voltage and broadband noise, spectra from 100% IC-Collapse groups consistently presented increased 2nd, 3rd and 4th harmonics compared to the 0% IC-Collapse group. Throughout the studied pressure range, best separation between 0% and 100% IC-Collapse groups was obtained with peak-voltage (4.7+/-1.8dB), broadband noise (4.4+/-1.8dB) and 4th harmonic (5.6+/-2.2dB) for Optison. For Definity, all harmonics (2nd to 4th) increased strongly for the 100% IC-Collapse group (on the order of 6 dB) as well as peak-voltage (5.3+/-1.2dB) and broadband noise (5.8+/-2dB). Results should contribute to relating PCD criteria and IC activity.
Blood-brain barrier disruption using a diagnostic scanner and Definity in mice
Authors: Frinkley Kristin , Howles-Banerji Gabriel , Qi Yi , Johnson G. Allan , Nightingale Kathryn
Published: May 2008

Objective: To quantify localized disruption of the blood-brain barrier (BBB) in a murine model using focused, diagnostic ultrasound (at higher frequencies than previously studied) and contrast agent and to explore the optimal parameters for opening without causing irreversible damage. Methods: Definity (US contrast) and Magnevist (MR contrast) were injected before a custom ultrasound transmission sequence. The volume of tissue over which the BBB disruption allowed Magnevist to enter the brain was quantified by the contrast in T1-weighted MR images. Results: Preliminary results suggest increased BBB opening with decreased time between Definity injection and insonification. A range of typical diagnostic frequencies (e.g. 5-8 MHz) has shown BBB disruption, with maximum contrast occurring at 5.7 MHz. Increasing pressure had an apparent threshold for visible opening, while increasing F/# led to a larger region of BBB opening and increasing duty cycle produced more contrast. Histology showed blood cell extravasation from B-mode imaging (MI=1.5, duty cycle=0.4%), but no damage was noted after the low-pressure, custom sequences. Conclusions: This study has shown the ability of a diagnostic ultrasound system and contrast agent to open the BBB for nanometer-scale particles (possibly drugs) and examined the effects of various parameters on this opening.
Influence of a rigid boundary on the resonance of an ultrasound contrast agent
Authors: Pauzin Marie-Christine , Mensah Serge , Lefebvre Jean-Pierre
Published: May 2008

Recent experimental studies showed that the behavior of an Ultrasound Contrast Agent (UCA) is strongly modified when located close or targeted to a vessel wall. Asymmetrical oscillations can occur and the frequency response differs from those of free UCA. To design new techniques for diagnostic or therapeutic applications with UCA, it is important to have a better knowledge of the acoustic behavior and the dynamics of UCA in vessels. We used a finite element model (FEM) to focus on how the resonance frequency is affected by a boundary. A FEM had been first developed with COMSOL Multiphysics to calculate the pressure field scattered by two types of spherical objects (air microbubble or UCA with a viscoelastic shell) immersed in an unbounded liquid. The results obtained with the FEM being coherent with analytical models, a rigid boundary was then added to study its influence on the frequency responses of both objects. We observed a decrease of the resonance frequency of both objects when they are close to the boundary. This behavior is in good agreement with experimental results found in literature. The model has been used to perform parametrical studies (distance to the wall, UCA radius, shell parameter...).
Photoacoustical evaluation of thermal response of microbubbles
Authors: Biagioni Angelo , Alippi Adriano , Bettucci Andrea , D'Orazio Annunziata , Germano Massimo , Passeri Daniele
Published: May 2008

Photoacoustic technique has emerged as a tool for the study of liquid, gel, suspension behaviour and has been recently employed in a number of new biomedical applications. In the present paper, a new photoacoustic sensor is presented which was designed and realized to analysing photoacoustic signals from solution filled with microbubbles, usually used as contrast agents in echotomography imaging. The device is a closed cell where photothermal expansion in acqueous solution samples causes the deflection of a thin membrane closing a short pipe 0.7 mm by radius. The overall set up acts as a Helmoltz resonator, where the solution in the pipe is the mass oscillating under the driving force produced by the alternating expansion of the solution in the cell body. Displacement of the membrane was measured using a laser probe interferometer, whereas photoacoustic signal was generated by chopping a laser light beam impinging into the solution through a glass window in the cell. The response of the cell filled with shelled microbubble solution was investigated with respect to water behaviour, at the cell resonance frequency and for different temperatures.
Dynamical focusing method for high-intensity ultrasound applications
Authors: Rybianets Andrey
Published: May 2008

New method for direct synthesis of dynamically focused acoustic field suitable for HIFU applications is proposed. The method is based on the continuous cyclic generation of different focal patterns at optimal repetition frequency by simultaneous applying of "M" different frequency signals to "N" sectors of spherically shaped sectored transducer array. The HIFU transducer arrays comprising a spherical piezoceramic cap with back electrode divided circumferentially into "N" regular or specially shaped sectors were designed and tested. The sectors were simultaneously powered by "M" (M ⩽ N) sinus or burst drive signals with different frequencies from 6 dB bandwidth of the transducer. Calculation and modeling of acoustic field patterns for different array configurations and frequencies sets were performed. Acoustic pressure in focal planes was measured in water using calibrated hydrophone and 3D acoustic scanning system. In vitro experiments on different tissues confirming the advantages of dynamical focusing method were performed. The benefits of the method are creating bigger treated tissue volumes and enhancement of the cavitational, mechanical or thermal influences due to coincidence of the repetition frequency with a specific resonance/relaxation times for tissue and/or for cavitation "cloud". Applications of the method for ultrasonic therapy, hyperthermia, and body aesthetics were considered.
Quantitative assessment of thermal dose using photographic measurements of tissue discoloration
Authors: Speyer Gavriel , Kaczkowski Peter , Brayman Andrew , Andrew Marilee , Kargl Steven , Crum Lawrence A.
Published: May 2008

High Intensity Focused Ultrasound (HIFU) is rapidly gaining widespread clinical use in China, and is undergoing regulatory evaluation in Europe and the US for many target diseases. Nevertheless, tools for therapy planning, monitoring, and assessment remain at a rudimentary level. In particular, measurement of thermal dose in tissues exposed with HIFU has not been sufficiently quantitative to make detailed comparisons with numerical simulations, required for validation of therapy planning models. Indeed, model validation is complicated by high sensitivity of the results to small changes in parameter values and by the general difficulty of performing geometrical registration with sufficient precision to meaningfully compare millimeter scale features typical of HIFU lesions. Our work uses photographic measurement of visible tissue discoloration so that it can be used to accurately and rapidly quantify HIFU-induced bioeffects at scales of several centimeters for comparison with the prior therapy plan. Precise comparison between nonlinear acoustic simulation and macroscopic lesion data indicates that a newly defined "blanching index" is nearly linearly proportional to the logarithm of predicted thermal dose over a very wide range of exposure, including well below the 240 minute (at 43 degrees) necrotic threshold up to about 10,000 minutes.
Acoustothermometrical control during hyperthemia of biological objects
Authors: Anosov Andrej , Kazanskij Aleksandr , Sharakshane Anton
Published: May 2008

A number of acoustothermometrical experiments modelling hyperthermia of biological objects was carried out. After that the first preliminary acoustothermometrical measurement of laser hyperthermia of human tissues was conducted. In all experiments the changes of the thermal acoustic radiation intensity in 1.4-2.2 MHz region were controlled during both the heating and the cooling of the object (about 8-10 minutes) with the help of set of acoustothermometers. As model objects we used the beef liver and glycerin water solution in which plasticine was placed. We reconstructed the 2-D inner temperature distribution by using acoustothermometrical experimental data, i.e. we calculated position, size and temperature of thermal source. The object surface temperature was controlled with the help of IR-thermograph. Acoustothermometrical measurements were carried out during laser hyperthemia of mammary and thyroid glands for seven patients. Obtained data allowed us to estimate inner temperature changes which were a result of laser hyperthemia.
Miniature diffraction-based optical MEMS microphones with integrated optoelectronics
Authors: Degertekin Levent , Jeelani Kamran , Qureshi Shakeel , Hasler Paul , Bicen Baris , Cui Weili , Su Quang T. , Miles Ronald N.
Published: May 2008

Diffraction-based optical interferometric sensing has been shown to be a low-noise displacement detection method for MEMS microphones. For this method to be useful in many important applications such as hearing aids, it needs to be packaged in a small volume and should have power consumption levels suitable for operation with a battery. In this talk, we describe miniature, packaged optical microphones that use solid state vertical cavity surface emitting lasers (VCSELs) as light sources and custom designed photodetectors. The package carries silicon chips with two micromachined biomimetic differential microphones as well as an omnidirectional microphone. It is made by 3-D laser stereo lithography process and has dimensions suitable for behind-the-ear hearing aids. With this configuration, the input referred noise floor for the differential microphone is measured as 42.6dBA, limited by the VCSEL intensity noise in this particular case. In addition to miniature packaging, an optoelectronic chip including VCSEL pulser, photodetectors, transimpedance amplifiers and 1 bit Sigma-Delta ADC has been implemented in 1.5V, 0.35u CMOS technology. The second order ADC structure providing 14-bits of theoretical resolution with 64 over sampling ratio and 20 kHz input signal is described and initial characterization results are presented.
Underground Sonar Using Shear Waves -Resolution improvement Using Pulse Compression and Dynamic Focusing-
Authors: Kawasaki Hiraku , Sugimoto Tsuneyoshi
Published: May 2008

In order to detect the buried relics and ruins at shallow depth, a method by using shear waves has proposed. The effect of the pulse compression processing is examined for improving the underground imaging resolution. Using a super-magnetostriction vibrator which can change waveforms and use high frequency waves, we generate both chirp waves and high frequency waves. To confirm the resolution of underground images, pulse compression is simulated. And, to confirm the lateral resolution, dynamic focusing is simulated in our laboratory. Then, its exploration experiment is carried out where the buried position has already known. The axial resolutions are smaller than 0.2m when the range of start and stop frequencies are more than 700Hz in the simulation. And the underground images obtained from exploration experiment confirm that the images by the pulse compression have almost the same axial resolution as by the result of the simulation.
Ultra-deep low-frequency sub-bottom profiler for AUV and ROV
Authors: Le Gall Yves , Pacault Anne , Mosca Frédéric , Greninguey Gilles , Vial Marcel , Aissa Jean-Claude
Published: May 2008

Acoustical techniques for ultra-deep sub-bottom exploration are still little investigated. IXSEA and IFREMER have launched in 2006 the development of a new deep-sea low-frequency sub-bottom profiler, working up to 6000 meters depth. Based on the Janus-Helmholtz broadband technology, two acoustic sources have been modelled, achieved and in-tank and at-sea measured : a single transducer working in the [1.8, 6.2 kHz] frequency band, and a three-transducer array operating in the [2, 8 kHz] frequency band. In both cases, vertical resolution is better that 20 cm. Comparison between finite element modelling and in-tank measurements is presented, together with the specific constraints linked to very-deep water and AUV mounting. Power electronics and impedance matching unit have been specifically optimised to deliver a sound level of 190 dB (ref. 1 μPa @ 1 m), with 48 VDC supply voltage and 250 W available electric power. The receiving part is made up of a three-hydrophone array with a loss of sensitivity lower than 1 dB between 0 and 600 bar. This ultra-deep light system has been mounted on an IFREMER's AUV and the first results at sea are presented and discussed.
An analytical model for piezoelectric/elastic axisymmetric bender disks radiating in water
Authors: Lardat Raphaël
Published: May 2008

Flextensional transducers have been widely studied for low frequency SONAR application due to the low celerity of the flexion wave. In this work, we will describe in detail a complete analytical model for an axisymmetric disk made of one elastic plate on which two piezoelectric disks of smaller radius have been reported on each side. The model, starting from flexural axisymmetric theory and from the piezoelectric equations, finally comprises local radiation impedance and mutual coupling with neighboring disks. In particular, we will explain the continuity conditions that are to be imposed at the external radius of the piezoelectric disk. We also show how to include a radiation force opposed and proportional to the normal velocity inside the analytical solution given by a fourth order differential equation. The described model is then able to compute a large number of parameters such as Eigen modes, harmonic admittance, radiated pressure, coupling coefficient and static and dynamic stresses. The validity of the model is assessed by comparison to solutions of the coupled problem in water using classical FEM/BEM. We will show an extremely good agreement enabling us to use this simple model for geometry optimization and design improvement.
The influence of braces on the playability of trumpets
Authors: Mayer Alexander , Egger Rainer , Widholm Gregor
Published: May 2008

The influence of braces on the playability, response and sound properties of the trumpet is an intense discussed subject for players and instrument makers. In addition to the problem of finding the proper position of the braces, inserted braces can produce stress between the instruments tubes. In this paper the influence of the tube stress is investigated. To ensure an adjustable and reproducible stress between the trumpet tubes special adjustable braces in conjunction with a force monitor are used. The results of blind playing tests are compared with spectral analysis of the played sounds. In addition, the acoustic input impedance, the wall vibrations and the transfer function of the instrument are investigated.
Chest wall dynamics and respiratory muscle recruitment during flute playing
Authors: Cossette Isabelle , Monaco Pierpaolo , Aliverti Andrea , Macklem Peter
Published: May 2008

Respiratory parameters and sound were recorded during professional flute playing in order to assess what physiological processes were associated with the control of sound production that results in 'breath support' which in turn is associated with high quality playing. Four standing young professional flautists played flute excerpts with different technical requirements with and without breath support. Recordings included optoelectronic plethysmographic measurements of chest wall volume (Vcw) and its compartments, surface electromyography of the scalene, lateral abdominal, rectus abdominus, parasternal and sternocleidomastoid muscles, mouth pressure, and sound. Flow was estimated from differentiating Vcw during playing. Comparison in between various types of playing were performed. Results showed that flute support entails antagonistic contraction of non-diaphragmatic inspiratory muscles that tends to hold the rib cage at higher lung volume during long legato phrase playing. This relieves the expiratory muscles from the task of producing the right mouth pressure, especially at the end of the phrases, so they can contribute more to the finer control of mouth pressure modulations required for high quality playing.
The Calibration and Validation of a Binaural Room Scanning System Used for Subjective Evaluation of Automotive Audio Systems
Authors: Olive Sean E. , Welti Todd
Published: May 2008

Binaural room scanning (BRS) is a method of capturing the acoustical response of audio systems in rooms and automotive cabins as a set of binaural impulse responses that are stored and later reproduced through head-tracking headphones. All BRS systems have errors that without careful calibration limit their usefulness for subjective measurements of sound quality. This paper discusses a method for calibrating and testing a proprietary BRS system based on how well it reproduces listeners' preference ratings of different automotive audio systems made in situ. A group of trained listeners gave preference ratings for 5 different equalizations of a high quality automotive audio system made both in situ and through the BRS capture/playback system. The tests were repeated in mono and stereo using 6 individualized listener calibrations. The results can be summarized as follows: there were no significant differences in preferences between the in situ and BRS-based evaluations for either the mono or stereo tests. A significant interaction was found between the different equalizations and individualized calibrations that were largely confined to 1 particular listener calibration. The results suggest that a generalized BRS calibration may provide sufficiently accurate preference measurements of audio system sound quality.
Head and torso simulators for acoustic measurements
Authors: Rasmussen Gunnar
Published: May 2008

Head and torso simulators which reproduce the acoustical effect of a median human adult, including diffraction and direction-dependent transformation from free field to the ear drum as well as allow for objective testing of sound systems involving hearing aids, headphones, earphones, telephones, mobile phones, headsets and sound quality type of measurements may be realized based on different philosophies. It may be based on geometrically simplified shape or mean values of individuals. The geometrically simplified shape will appear like no human being. The mean values may result in non human like features, while average anthropometric dimensions of an adult human may offer data closer to a subjective test. Especially the shape of the pinna may often be critical to test of earphones and headphones as well as mobile phones. Subjective tests on groups of people may be supplemented with objective tests on a manikin for reference and quality control purposes. Variations in pinna size may have significant influence on the measurement of earphones as well as leakage in telephone testing. The influence of the dress worn may also be of significance especially for the head related transfer function and on the directional response in the middle frequency range.
PsySound3: a program for the analysis of sound recordings
Authors: Cabrera Densil , Ferguson Sam , Rizwi Farhan , Schubert Emery
Published: May 2008

This paper demonstrates the sound analysis software PsySound3, which was written by the authors. The software currently includes a range of DSP-based analysis techniques (e.g., spectrum, cepstrum, autocorrelation, Hilbert transform, sound level meter emulator), as well as implementations of psychoacoustical algorithms often associated with sound quality (e.g., loudness, sharpness, loudness fluctuation, roughness, pitch, binaural attributes). In some cases, PsySound3 makes available multiple models of the one auditory attribute - for example it implements dynamic and static loudness models using Erb- and Bark-based auditory filters. The program is extensible, and so has the potential to allow researchers to share their analysis models using a common interface. PsySound3 is written in Matlab, and is also available as a stand-alone program. The software is freely available from www.psysound.org.
Hartis, a re-synthesis tool for vehicles sound design
Authors: Desoeuvre Gaylord , Richard Florent , Roussarie Vincent , Bezat Marie Céline
Published: May 2008

For more than thirty years, the main goal for the automotive acoustic engineer was the car's noise level reduction. Within new customers' behaviours, the car manufacturers have now to put products sound quality at the same level as its aesthetic qualities or ergonomics. To improve customer's satisfaction, one solution is to increase sensory coherence and perceived quality by controlling the sound identity and character of a vehicle. To reach this new objective, the Research Department of PSA Peugeot Citroën is developing his own sound design software HARTIS [1] (HArmonics Real TIme Synthesis). HARTIS is a complete re-synthesis tool useful in many stages of vehicle sound design process. In this paper we first present the last version of HARTIS fully interfaced for an easy use in project teams. The second part of the paper presents new integrated module that deals with impulsional noise for diesel application and other sources models. Each type of source can be controlled and filtered to recreate different driving situation. References [1] Sound design in car passenger compartment Process and tool for the control of engine sound character. V. Roussarie, F. Richard, Journées du Design Sonore 2004.
Noise computation of an axisymmetric free jet using general purpose CFD code
Authors: Tóth Péter , Lohász Máté Márton
Published: May 2008

The increasing interest in the noise prediction of the turbulent flows is leading the general purpose Computational Fluid Dynamics (CFD) software developers to integrate noise predicting methods into their code. However the aeroacoustic simulation of free shear flows, where the mean source of noise is the turbulent fluctuations in the free space is challenging with a general purpose CFD application. The aim of this work is to investigate the capabilities of commercial CFD software in the field of noise prediction of free shear flows. The important acoustical properties of a low Reynolds number, low Mach number axisymmetric (2D) jet is computed by means of hybrid Computational Aeroacoustic method using Fluent. The noise source is computed without modeling instantaneously using the compressible solver of the code, and the far field acoustical data is evaluated by the Ffowcs-Williams-Hawkings acoustical analogy. The results is compared to the Direct Numerical Simulation of [Jiang2004 J. Sound Vib.] in terms of frequency spectra in the far field and directivity pattern of the jet.
Instability wave control in a subsonic round jet
Authors: Faranosov Georgy
Published: May 2008

It is generally accepted that one of the main sources of acoustic radiation from a turbulent jet is due to spatial instability wave packets propagating downstream within the jet. This approach has enabled to explain and predict the principal features of sound radiated by a supersonic jet. Therefore the problem of noise control for the jet could be considered as a problem of instability wave control. Instability wave developed in the tone-excited jet issued from axisymmetric, semi-infinite duct is considered. The flow field in the vicinity of the nozzle edge is investigated for the purpose of identifying instability wave parameters. Instability wave turned out to be damped completely on the condition that the amplitude and the phase of the external forcing are chosen in accordance with those of the instability wave. The robust strategy of instability wave experimental suppression based on the near field measurements is formulated. Similar problem in two-dimensional case was recently analyzed in Kopiev & Faranosov (Acoust. Phys. 2008, V.54, N.2).
Origins of the modern noise ordinance in the County of San Diego, California
Authors: Bennett John C.
Published: May 2008

An unofficial history of the origins of San Diego County's noise regulations has been compiled as an investigative tool to review current and future zoning schemes in this jurisdiction. These regulations date back to the 1970's and overlap with the development of city regulations. The focus of the history is the acoustical aspect of their development. A general discussion of performance standards is included in a comparison with similar regulations in two other California jurisdictions developed within the last five years. Some practical similarities and differences with European regulations in local jurisdictions are identified to encourage an open discussion in this session.
Investigation and application of theoretical acoustic field model evaluating the change of environmental conditions
Authors: Mikalauskas Robertas , Volkovas Vitalijus
Published: May 2008

The effectiveness of the means used to reduce the noise depends on many factors. One of the main factors is the sources which generates acoustic field. In industrial premises there are many sources, their impact to acoustic field differs, and the source may also change due to environmental conditions. Therefore the task of the creation of the mobile noise reduction means, their rational arrangement and control becomes more and more relevant. In this case theoretical modeling of interaction of acoustic noise control systems with environment has significant importance for creating such systems. This paper provides acoustic field model using FEM, which imitates changing conditions of real industrial premise, evaluates the effectiveness and application possibilities of the mobile noise reduction system. It also provides the comparison of the results of theoretical experiment with experimental results. The results showed that with the help of the model mobile noise reduction system can be modeled, their effectives might be evaluated considering the change of sources and reflection planes, and the structural model of the investigative room can be supplemented with acoustic noise reduction means - noise reduction screens, selecting their geometric dimensions, arrangement in the space and selecting the materials and predicting the values of acoustic field parameters in the real object point under consideration.
Effect of coolant temperature on combustion and combustion noise fluctuations in a Diesel engine at idle conditions
Authors: Gazon Matthieu , Blaisot Jean Bernard , Duclaux-De-L'Estoille Nicolas , Wang Shanjin
Published: May 2008

At idle conditions, the cycle-to-cycle fluctuations in Diesel engines lead to combustion noise variations that could be annoying for people, even if the mean level is low, and the cold start condition is one of the worst cases. This study focuses on the effect of injection parameters (duration and timings) and the effect of coolant temperature on combustion characteristics and on the combustion noise. A Direct Injection Diesel engine (four cylinders, 16 valves) equipped with a common-rail injection system and piezoelectric injectors was used. The coolant temperature is changed at idle from the ambient temperature to the temperature at normal working conditions. The combustion is analysed in terms of rate of heat release and combustion noise through the measurement of the cylinder pressure. The results show the dependency of the combustion behavior on the increase of coolant temperature at constant engine adjustment parameters. It is also shown that acting on adjustment parameters can modify the combustion behavior and, consequently, the cycle-to-cycle fluctuations. A trade-off between combustion noise and engine emissions can thus be reached.
Sound perception of urban delivery trucks
Authors: Manca-Demirdjian Florence , Parizet Etienne
Published: May 2008

The study deals with the annoyance of urban delivery trucks noises. Sound sequences of two lorries were recorded during a typical delivery : a commercial one and a prototype specially designed to reduce sound emissions. Various sources could be heard during these sequences (engine, doors, hydraulic rear doors). These recordings (the duration of which being more than 5 minutes) were evaluated by subjects in a sound proofed room by two methods. The first one was a continuous assessment of sequences : the listeners had to continuously assess their annoyance by moving a cursor sliding along a five levels graduated scale (from "not at all annoying" to "extremely annoying"). The second one was an overall evaluation (using the same scale) of each event of the sequences (for example : the arrival of the truck, or the closing of the driver's door, etc...). The comparison of the results obtained from these two methods for both lorries will be presented, as well as the reduction of the annoyance could be realized on the prototype.
Low frequency noise impact of road traffic in the Netherlands
Authors: Jabben J. , Schreurs Eric
Published: May 2008

Current traffic noise impact assessments are usually based on broadband A-weighted noise indicators. A more complete picture and better correlation with annoyance and health effects may result from indicators that include temporal aspects and frequency character. These aspects are currently under investigation at RIVM. This paper gives an evaluation of low frequency noise impact from road traffic in the Netherlands. The results are based on low frequency noise maps covering the entire road network. In particular the effectiveness of various types of noise control measures, such as noise barriers or walls, porous asphalt layers and reduction of noise emission, with regards to low frequency impact were studied. The results indicate for low frequency noise levels, powertrain noise and freight traffic in general, are of major importance for environmental quality.