bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and construction of an acoustic lab facility
Authors: Winker Douglas
Published: May 2008

This paper will discuss the design and construction of a new acoustic lab facility. The lab consists of a hemi anechoic chamber and a reverberation chamber suite. The hemi anechoic chamber was designed to obtain a 0 dBA noise floor in the frequency range of interest. It features a 200 cubic meter volume inside the wedges. To achieve the design goals, several aspects were considered including ambient levels, vibration isolation, HVAC noise, and free field performance. The design solutions for each of these areas will be presented. The reverb chamber suite consists of two reverberation chambers designed to perform transmission loss tests and sound absorption testing. The source chamber has an internal volume of 214 cubic meters and the receive room has an internal volume of 418 cubic meters. Design considerations will be discussed including vibration isolation, wall panel design, and diffuser placement. Additionally, the design and construction of the transmission loss coupling will be addressed.
Measurements of existing modular construction classroom acoustics in the Midwestern United States
Authors: Philipp Norman , Wang Lily M.
Published: May 2008

Modular construction classrooms in the United States currently total more than 300,000 units, with 37% nationally of all public schools utilizing portable classrooms, according to the Modular Building Institute and a 2007 survey of Public School Principals conducted by the National Center for Education Statistics. Given this ever growing number there is a desire to improve their acoustics to meet ANSI S12.60-2002 guidelines for classroom acoustics. This paper gives a survey of existing acoustic conditions of re-locatable classrooms currently in use in the Midwestern United States. Data to be presented include reverberation times, interior/exterior noise reduction, and site noise measurements. The results of these measurements and additional qualitative surveys will aid in understanding the performance of modular classrooms and assist in drafting a standard for them to supplement the guidelines in ANSI S12.60-2002.
Approximation of single equivalent mobilities of timber joist floors
Authors: Mayr Andreas R. , Gibbs Barry M.
Published: May 2008

To estimate the structure-borne sound power of vibrational active machines or components two source quantities, corresponding to the source activity and mobility, and one receiver quantity, the mobility, are usually required. A practical, laboratory-based measurement procedure for the characterisation of mechanical installations has recently been proposed, which yields single equivalent values of source strength and source mobility. In order to predict the power in the installed condition, an estimate of the receiver mobility also is required, again, for practical reasons, in the form of a single equivalent value. This paper considers the single equivalent receiver mobilities for lightweight building structures - timber joist floors. The value obtained is in the form of the average magnitude of the effective mobilities over the contact points. A simple prediction method is proposed for point- and transfer mobilities (both are required to yield the effective mobility at each contact) based on infinite beam and infinite plate behaviour. Estimates for point-, transfer- and single equivalent receiver mobilities are discussed and compared with measured data.
Prediction of the impact sound transmission from lightweight stairs in buildings based on a simplified laboratory characterisation
Authors: Drechsler Andreas , Scheck Jochen , Fischer Heinz-Martin
Published: May 2008

Based on a simplified laboratory characterisation of lightweight stairs the normalized impact sound pressure level in buildings can be predicted using parts of EN 12354. For the characterisation an approach is followed where the stair is treated as an active component with respect to an external excitation (e.g. by the tapping machine). The laboratory characterisation was performed for a timber stair and the normalized impact sound pressure level was predicted for different building situations. The various transmission paths via the separating and flanking walls were investigated and compared to the prediction according to EN 12354. Within the presentation the proceeding will be outlined and the restrictions are discussed. By comparison of measured and calculated values some references for the accuracy of the method are obtained.
Reciprocity and the Prediction of the Apparent Sound Reduction Index for Lightweight Structures According to EN12354
Authors: Mahn Jeffrey , Pearse John
Published: May 2008

EN12354 makes use of reciprocity to cancel the radiation efficiency terms from the equations used to predict the apparent sound reduction index. The use of reciprocity works well for the application of EN12354 to massive, concrete structures with diffuse wave fields and with critical frequencies below the frequency range of interest. However, lightweight constructions may have critical frequencies above the frequency range of interest and may not support diffuse wave fields. The use of reciprocity for application to lightweight structures may introduce errors into the predictions. This study investigates the uncertainty introduced into the predictions of the apparent sound reduction index of lightweight constructions due to the use of reciprocity.
Direct and flanking sound transmission of solid gypsum walls - practical experience and numerical prediction
Authors: Ruff Andreas , Fischer Heinz-Martin
Published: May 2008

In modern multi storey buildings gypsum blocks are often used for solid inner walls without static requirements. However, these relatively light walls with a mass per unit area of about 90 kg/m2 are not connected rigidly to the adjacent building elements. They are decoupled with elastic interlayers made of bitumen, cork or polyethylene foam. These elastic interlayers have a significant influence on the direct and the flanking sound transmission of the gypsum walls. For this reason the decoupled walls have to be considered different to rigidly connected walls. Within a recent research project there was an extensive investigation into the direct and the flanking sound transmission of gypsum walls in different test facilities in the laboratory. For several kinds of elastic interlayers the sound reduction index of gypsum walls was measured in the test stand for direct sound transmission. The vibration reduction index was investigated in a test facility for flanking transmission as well as in different building situations. The measured values are used as input data for the prediction model according EN 12354-1. The overall sound reduction index calculated with this prediction model is compared with the results measured in the buildings.
An hybrid method for sound transmission through opened windows
Authors: Jean Philippe A. , Villot Michel
Published: May 2008

An hybrid model for the calculation of sound transmission between apartments when windows are opened is presented. It is an extension of Kropp's model for balconies (integral/modal/wave approach). Two rectangular rooms are set in a baffle with rectangular openings. A point source is placed in one room and sound attentation between rooms is computed. The external field may include the ground and a nearby building by means of a combined image source approach to compute a Green function in the integral description at the openings. Results are validated against BEM and published measurements. SEA is employed to assess the importance of vibration transmission relative to airborne transmission through the external medium.
Directional distribution of acoustic energy density incident to a surface under reverberant condition
Authors: Jeong Cheol-Ho , Ih Jeong-Guon
Published: May 2008

Most of acoustic measurements presume ideal conditions: one ideal condition is a diffuse and reverberant field. In a practical situation, diffuse sound field in a reverberation chamber can not be achieved. In particular, the directional diffusion which means the uniform angular distribution of incident direction can not be satisfied. Angle dependency of incident energy density was simulated by the phased beam tracing simulation. Various results were found by changing room shape and source position, and number of sources. Acoustic energy generally decreases with the angle of incidence. This result can be used as a weighting function for the calculation of sound transmission index and random incidence absorption coefficient.
Investigation into the possible role of dolphins' teeth in sound reception
Authors: Graf Sabine , Megill William M. , Blondel Philippe , Clift Sally E.
Published: May 2008

Odontocetes use active sonars for echolocation, navigation and socialisation. These sonars are characterised by narrow transmission and reception directivity patterns, over a variety of ranges. There is physiological and behavioural evidence to suggest that dolphins hear the echoes of their high-frequency clicks through their lower jaws. Current theory suggests that sound is transmitted through a thin region at the base of the jaw into a waveguide leading to the ear. The angular precision predicted by this theory is however much less than dolphins have been observed behaviourally to be able to do. A novel hypothesis is that the teeth of the dolphin's lower jaw act as an end-fire sonar array. This paper will start by putting these competing hypotheses into their context, presenting bioacoustics in the ocean, dolphin echolocation physiology and acoustic behaviour, and the mechanical properties of bones and teeth. This information is used to model the reception of different sounds by bottlenose dolphins (tursiops truncatus) with each possible mechanism, investigating the variations with nerve delay, the role of the jaw relative to the teeth, and the resulting changes in frequency sensitivity and directivity. The results can then be compared with observations of behavioural patterns.
Acoustic behavior of echolocating porpoises during prey capture
Authors: Deruiter Stacy , Bahr Alexander , Blanchet Marie-Anne , Hansen Sabina , Kristensen Jakob , Madsen Peter T. , Tyack Peter , Wahlberg Magnus
Published: May 2008

Porpoise echolocation has been studied in target detection experiments using stationed animals and steel spheres as targets, but little is known about the acoustic behavior of free swimming porpoises as they echolocate for prey. Here we used archival tags (modified Dtags) recording audio (400 kHz, 16-bit stereo sampling rate) and animal movements (depth, heading, 3D pitch and roll, and acceleration) to study echolocation in trained porpoises catching fish. The prey capture experiments were conducted with and without suction cups covering the porpoises' eyes. Without the eye cups, the porpoises could use both echolocation and vision to locate and ingest their prey, but with eye cups they could use only echolocation. Our data show that time to prey capture is about 27% greater with eye cups (T-test, p<0.01). They also allow us to describe and compare prey capture in the two experimental conditions, including analysis of the animals' detailed movements and echolocation behavior leading up to and following prey capture events.
Acoustics of shape recognition by a dolphin in a cross-modal matching-to-sample paradigm
Authors: Hoffmann-Kuhnt Matthias , Chitre Mandar A. , Seekings Paul J. , Abel Grant
Published: May 2008

A pacific bottlenose dolphin was trained in a two-alternative cross-modal matching-to-sample paradigm. The animal was able to inspect complex PVC-pipe shapes through echolocation or vision but never through both senses simultaneously. Acoustic data was collected through a 3-channel high-frequency recording system while the dolphin performed one of the following tasks: (1) match a complex shape with its sonar only (pure echoic matching), (2) match from vision to echolocation and (3) match from echolocation to vision. Simultaneously, synchronized in-air and underwater video was recorded documenting the approach path of the dolphin to either the sample object or to the alternative objects. The collected data was analyzed for type of click signals used, the frequency range of the emitted clicks, number of clicks emitted before a successive match and variations of click type with different objects.
Spatial confirmation of vocal communication between a killer whale calf and its natal family
Authors: Veirs Scott , Veirs Val , Wood Jason D.
Published: May 2008

We recorded an interchange of vocal signaling between a four-year-old Southern Resident killer whale and its natal family members (mother and brother). This information was recorded on a 30-m-long linear array of hydrophones that was towed behind our electric motor powered research vessel. Over the course of about 1/2 hour we recorded signals from these isolated orcas about 500 m offshore of San Juan Island, WA. Surface locations of the orcas were documented with visual accounts, photographs, video, and - during the latter portion of the encounter - with a hand-bearing compass. During a six minute interval of the recording we have localized ̃70 vocalizations that we can associate with the surface positions of either the juvenile or the mother-brother pair (they were close together). The central three minutes of this interval document an event in which the juvenile left the family group, swam toward our vessel, approached it within about 10m, turned abruptly away during a rapid call-response sequence with the mother and/or brother, and then rejoined the natal group. This rare event informs killer whale vocal development, repertoire, communication, and active space.
Whistle repertoire of captive bottlenose dolphins, Tursiops truncatus
Authors: Lopez-Rivas Rebeca M. , Deecke Volker B. , Bazúa Durán Carmen
Published: May 2008

The whistle repertoire of bottlenose dolphins has been poorly described in the literature, thus little information is known to support the hypothesis that whistles are used by dolphins to communicate. In this study, whistles emitted by four captive bottlenose dolphins housed in two aquaria in Mexico City were recorded to analyze the whistle repertoire and whistle emission rate for each aquarium. The whistle repertoire was described using human and automated categorizations. Results show that whistle emission rate and the whistle repertoire are both larger for the two dolphins that are more active and which are housed in the same aquarium. As for whistles shared in the repertoire of both aquaria, these are very few, probably because dolphins of the two aquaria were captured in different oceans and are of different ages, besides of the different activities that dolphins can perform in each aquarium. Additionally, all four dolphins could use similar whistles for a specific activity, like "swimming", while different whistles were used for another specific activity, like "observing". These results show that dolphins use whistles selectively, supporting the hypothesis that whistles may be used to communicate information for particular situations. [Work supported by PAPIIT, UNAM & CoNaCyT]
Unsupervised clustering of whistle-sounds of bottlenose dolphins (Tursiops truncatus)
Authors: Huebner Sebastian V.
Published: May 2008

An unsupervised symbolic clustering algorithm for whistles of bottlenose dolphins (Tursiops truncatus) was tuned on an artificial data set containing 12 ideal synthetic signature whistles. Afterwards approximately 25,000 representations of natural whistles were clustered with the tuned algorithm. Recordings were made from a group of twelve adult semi-free living animals in Eilat (Israel). Obtained clusters were evaluated with the help of their individual compression rates. The clustering algorithm perfectly converged on all twelve artificial whistle types. Also, automatic whistle extraction produced good representations of both artificial and natural whistles, but clustering of natural whistles provided low support for the signature whistle hypothesis: The six most frequent induced whistle types could be interpreted as slight variations of only two signature whistles. Also, a great variety of different but rare types in automatically generated clusters could be observed. Results suggest that certain aspects of the group behavior are manifest in the frequency whistle types occur.
Acoustic studies of dolphins in their natural habitat: Challenges and successes
Authors: Kim Katherine , Hursky Paul , Porter Michael B. , Hildebrand John A. , Henderson Elizabeth , Calambokidis John , Falcone Erin
Published: May 2008

Acoustic methods for studying marine mammals is a research area of great potential, with applications which include population estimation, spatial distribution, behavioral studies, and the effects of anthropogenic noise on animals. Until recently, much of the acoustic research on free-ranging animals has focused on mysticetes and sperm whales; however, concern over highly-publicized dolphin strandings has raised interest in other odontocetes. From acoustic and signal processing perspectives, dolphins pose numerous new challenges: They typically aggregate in pods composed of tens or hundreds of individuals, often vocalizing simultaneously, and their calls are highly variable and high-frequency. Detection algorithms will be presented which are robust (or, conversely, can be fine-tuned) to these variable calls and have been automated to overcome the ordinarily labor-intensive analysis requirements of such large data sets. Historically, acoustic studies of marine mammals used relatively simple sensor systems comprised of one or few hydrophones. In our studies, multiple sensor systems were deployed. Doing so enabled the utilization of array and co-array processing techniques for improved localization estimation which, like our detection algorithms, were fully automated. They also raised important deployment considerations due to the acoustic propagation physics as well as challenges in call association between different systems.
Geoacoustic inversion in the frequency range 0.8-1.6 kHz with drifting sparse arrays during MREA/BP'07 experiment
Authors: Le Gac Jean-Claude , Hermand Jean-Pierre , Jesus Sergio
Published: May 2008

In order to evaluate properly the acoustic propagation characteristics in shallow water environments, it is well established that appropriate knowledge of the acoustic properties of the seabottom is required. In the last decade, full-field geoacoustic inversion techniques have been demonstrated to provide adequate methodologies to assess those properties. However, several of the developed techniques may suffer a lack of adequacy to the design of low-frequency active sonar systems (LFAS) for which the assessment of seabottom characteristics are drawn. For instance most matched-field inversion techniques demonstrated so far use acoustical signals at much lower frequencies than those of the sonar. Furthermore, some of the techniques may be difficult to be handled in an "operationally relevant context" since they are based on relatively complex designed systems such as highly instrumented vertical line arrays spanning the whole water column. In this paper, we investigate the potential of medium-frequency acoustical signals (0.8-1.6 kHz) received at several ranges on a field of drifting sparse arrays, eventually reduced to a couple of hydrophones, for spatially-coherent geoacoustic inversion purposes. The experimental datasets of the Maritime Rapid Environmental Assessment MREA/BP'07 sea trial south of Elba Island in the Mediterranean Sea are used to support this study.
Using offshore seismic surveys as acoustic sources of opportunity for geoacoustic inversion
Authors: Duncan Alec J. , Gavrilov Alexander , Hu Tao
Published: May 2008

Commercial offshore seismic surveys involve the use of powerful acoustic sources consisting of arrays of airguns. These sources produce frequent, loud, impulsive sounds at precisely timed intervals, at accurately known positions during surveys that may last for several months. By deploying a low-cost acoustic receiving system in the vicinity of such a survey scientists can acquire high quality data for geoacoustic inversion experiments in an extremely cost-effective manner. This paper discusses the various factors that must be considered when using such data for geoacoustic inversion, including the prediction of source spectra and array directionality, and provides some examples.
Short- and long-delay tandem shock waves for application in medicine
Authors: Loske Achim M. , Fernandez Francisco , De Icaza Miguel , Canseco Guillermo
Published: May 2008

Long-delay tandem shock waves with an inter-pulse delay between about 200 and 500 microseconds have shown to enhance fragmentation of artificial kidney stones during in vitro and in vivo extracorporeal shock wave lithotripsy (SWL) in the past. Cell-permeabilization and inactivation of bacteria using tandem shock waves have also been proposed. The purpose of this research was to study the influence of short-delay (less than 50 microseconds) tandem shock waves on cavitation induced damage to kidney stones during SWL. A multipurpose piezoelectric shock wave generator was designed to generate shock waves at variable delays. The effect of short- and long-delay dual-pulse shock waves on the surface of artificial kidney stones was evaluated by microscopy. An adequate selection of delays was possible by means of a numerical model and high speed photography. Stone fragmentation was compared to that of standard (single-pulse) shock waves. Our results indicate that specific combinations of short- and long-delay tandem shock waves could improve damage to kidney stones by acoustic cavitation.
Correlation of vasoconstriction and kidney protection during shock wave lithotripsy
Authors: Bailey Michael R. , Paun Marla , Handa Rajash K. , Gao Sujuan , Willis Lynn R. , Connors Bret A. , McAteer James A. , Evan Andrew P.
Published: May 2008

Kidney injury in lithotripsy can lead to long-term adverse effects, so minimizing injury is beneficial. We have found that injury is significantly reduced when shock wave (SW) administration is halted briefly- 3-minutes-early in treatment. Previous studies have shown that SWs stimulate renal blood vessels to constrict. Therefore, we tested the idea that vasoconstriction mediates SW-induced protection of the kidney. Doppler ultrasound was used to measure resistive index (RI), a ratio of systolic and diastolic velocities, indicating vasoconstriction. RI was determined for single intralobar arteries in targeted porcine kidneys treated by standard versus protection protocols (2,000SW, uninterrupted vs 500SW-3-min pause-2,000SW) using a Dornier-HM3 lithotripter (2Hz, 24kV). Significant differences in RI from baseline within a group and between groups at various time points were determined using mixed-effect models for repeated measures with Holm's step-down method for multiple comparison adjustment. All animals had similar baselines. Sham pigs (no-SWs) showed no significant change in RI. The protection protocol produced a significant rise (p<0.05, n=8) in RI 15 minutes into treatment, while the standard protocol did not yield a significant rise (p<0.05, n=7) until 45 minutes after treatment. Thus, the treatment protocol shown to protect against injury, induces early vasoconstriction. [NIH-DK43881, NSBRI-SMS00402]
Beamwidth measurement of single lithotripter shock waves
Authors: Kreider Wayne , Bailey Michael R. , Ketterling Jeffrey A.
Published: May 2008

New lithotripters with narrower foci and higher peak pressures than the original Dornier HM3 electrohydraulic lithotripter have proven to be less effective and less safe. Hence, accurate measurements of the focal characteristics of lithotripter shock waves are important. The current technique for measuring beamwidth requires collection of single-point measurements over multiple shock waves, thereby introducing error as a result of any shock-to-shock variability. This work reports on the construction of a hydrophone array sensor and on array measurements of individual lithotripter shock waves. Beamwidths for an electrohydraulic lithotripter with a broad-focus, HM3-style reflector and a narrow-focus, modified reflector were measured using both new and worn electrodes as well as two different electrical charging potentials. The array measured the waveform, beamwidth, and focal location of individual shock waves. The HM3-style reflector produced repeatable focal waveforms and beam profiles at an 18-kV charging potential with both new and worn electrodes. Accordingly, these measurements agreed with averaged point measurements acquired under the same conditions. However, a lack of consistency in the measured focal locations and beam profiles at 23 kV underscores the value in obtaining beam profile measurements from individual shock waves. Work supported by Riverside Research Institute, NIH DK43881, and NSBRI SMS00402.
Effect of elastic waves in the metal reflector on bubble dynamics at the focus of an electrohydraulic lithotripter
Authors: Sapozhnikov Oleg A. , Kreider Wayne , Bailey Michael R. , Khokhlova Vera A. , Curra Francesco
Published: May 2008

In extracorporeal electrohydraulic lithotripters, a hemi-ellipsoidal metal reflector is used to focus a spherical wave generated by an electrical discharge. The spark source is positioned at one of the ellipsoid foci (F1); this makes the reflected wave focused at the other focus (F2). Despite the common assumption that the reflector behaves as a rigid mirror, the true reflection phenomenon includes the generation and reverberation of elastic waves in the reflector, which reradiate to the medium. Although these waves are much lower in amplitude than the specularly reflected wave, they may influence cavitation at F2. To explore such effects, waves in water and a brass reflector were modeled in finite differences based on the linearized equations of elasticity. The bubble response was simulated based on a Rayleigh-type equation for the bubble radius. In addition, the role of acoustic nonlinearity was estimated by numerical modeling. It is shown that the elastic waves in the reflector give rise to a long "ringing" tail, which results in nonmonotonic behavior of the bubble radius during its inertial growth after shock wave passage. This numerical result is qualitatively confirmed by experimental observations of bubble behavior using high-speed photography. Work supported by NIH-DK43881, NSBRI-SMS00402, NIH-DK075090, and RFBR.
The role of ultrasound and photoacoustic imaging in laser therapy of cancer
Authors: Emelianov Stanislav Y.
Published: May 2008

Laser therapy is an alternative cancer treatment approach when traditional surgery cannot be used to remove small, poorly defined lesions embedded within vital organs. For example, in photothermal laser therapy, a localized temperature increase to cause tumor necrosis is achieved by using a continuous wave laser and molecular targeted and optically tuned photoabsorbers. However, for laser therapy to be successful, it is necessary to identify the presence of photoabsorbers in the tumor prior to therapy, to monitor the spatio-temporal temperature changes during therapy, and, finally, to identify thermal/mechanical damage and tumor destruction after therapy. To guide laser therapy, we developed a combined ultrasound/photoacoustic imaging system and bioconjugated nanoabsorbers. In our approach, ultrasound imaging is utilized to identify the anatomy of the tumor while photoacoustic imaging is used to ensure the presence of targeted nanoparticles before therapy. Both ultrasound and photoacoustic imaging techniques are then used to monitor temperature during therapy, ensuring tumor necrosis and protection of the surrounding healthy tissue. Finally, ultrasound and elasticity imaging is used to confirm thermal damage and cancer destruction. The results of our studies indicate that photoacoustic and ultrasound imaging can be used to effectively guide laser therapy.
Optoacoustics for biomedical sensing, monitoring, and imaging
Authors: Esenaliev Rinat O.
Published: May 2008

Optoacoustics can provide diagnostic information with high optical contrast and ultrasound resolution. It is based on detection of broadband ultrasound induced by short optical pulses and utilizes absorption contrast in tissues. We proposed and developed sensing, monitoring, and imaging optoacoustic systems for in a variety of biomedical applications including pulsed laser tissue ablation, accurate measurement of tissue optical properties, tumor detection, monitoring of tissue hyperthermia, coagulation, freezing, and important blood parameters such as oxygenation and hemoglobin concentration. Recently, we built a novel, portable, multi-wavelength optoacoustic system which includes optical parametric oscillator operating in the range from 680 to 2400 nm and sensitive, broadband optoacoustic probes developed in our laboratory. We tested the system performance in animal and clinical studies. We monitored continuously and in real time cerebral blood oxygenation and total hemoglobin concentration. Direct probing of blood vessels with high contrast and resolution allowed for monitoring of these parameters with accuracy approaching that of the standard invasive techniques. Results on other important clinical applications of the optoacoustic technique will be presented as well.
Cylindrical ultrasonic array for borehole applications
Authors: Liang Kenneth , Fleury Gérard , Froelich Benoit , Guey Jean-Luc , Schoeb Pascal
Published: May 2008

A cylindrical ultrasonic array has been developed for operating environments that can reach extremes of 175 C and 20,000 psi. The array is a key component of the PharUSIT* (Phased Array Ultrasonic Transducer for Inspection of Tubing), a research demonstrator developed for borehole applications. The full array consists of 800 elements (10 rings of 80 elements each) and can provide a whole range of beam-forming versatilities and capabilities in 3-D, such as variable focusing, beam steering, electronic scanning, etc, all accomplished without mechanical movements. Special piezo-composites have been developed for the transduction layer, and new polymeric composites have been formulated for the backing material. The center frequency was chosen to be about 500 kHz to accommodate attenuation of the propagation media. A novel technique utilizing custom flexible circuit provides electrical connections between the array and the front-end electronics. Special fabrication processes have been developed to construct the array in a cylindrical geometry. A customized testing protocol has been implemented to demonstrate the survivability of the array technology and to evaluate the performance characteristics of individual elements under high-temperature/high-pressure conditions. The unique experimental setup will be presented. Data from electroacoustic measurements such as electrical impedance, bandwidth, sensitivity, angular directivity, and inter-element cross-talks will be shown. *EC GROW project PharUSIT (GIRD-CT-2002-000689)
Extracting dispersion curves of acoustic data with continuous wavelet transform
Authors: Valero Henri-Pierre , Bose Sandip , Aeron Suchin
Published: May 2008

Group and phase velocity (i.e. dispersion) of acoustic data carry important information about the acoustic state of the rock and are important tools for interpretation and for quantitative inversion. In this paper we propose an approach to automatically extract the velocity dispersion (group and phase) of acoustic waves received by an array of receivers without the use of any physical model, user inputs or supervision. The first step consists in applying the continuous wavelet transform to the waveforms recorded by each receiver. Then, the peak on the modulus map is used to determine the time locus of the energy of each mode as a function of frequency. At each frequency, a method of data association is used to find the corresponding loci for all receivers. A straight line is fit to these loci and its slope is used as an estimate for the group velocity at that frequency. Moreover the rate of change of the phase of the complex wavelet coefficients at the locations corresponding to this best-fit straight line can be used to compute an estimate of the phase slowness at the same frequency. Repeating this for all frequencies and all separated modes of interest yields the desired dispersion curves for these modes.
Small scale adaptation of the seismic full waveform inversion method - Application to civil engineering applications
Authors: Bretaudeau Francois , Leparoux Donatienne , Abraham Odile
Published: May 2008

Full Waveform Inversion (FWI) is a very general multi-parameters quantitative imaging method originally developed to obtain high resolution images of velocities and attenuation in the natural underground media. FWI promises interesting performances for civil engineering applications like cavity detection. Performances of the FWI method in seismic exploration are difficult to quantify because in real experimentations, the properties of the media are not known. Furthermore, characteristics of the source and coupling of receivers are not controlled. In order to quantify the performances of FWI and its adaptability to near subsurface applications, small scale physicals models are realized and a non-contact laser ultrasonic laboratory is dedicated to simulate seismic reflection measurement configurations at ultrasonic scale. Seismograms well reproduce real scale data in terms of waveforms and repartition of energy. A FWI algorithm developed by Geosciences Azur and applied in geological investigation is used. The direct part of the algorithm uses a frequency domain finite difference modelisation. The inverted model is obtained by using a Gauss-Newton method of optimization. Results of inversion of multi-receivers and multi-sources data obtained from simple physical models are presented.
Micro-viscometer using acoustic wave absorption in micro-chamber and channel
Authors: Choi Sungjoon , Moon Wonkyu , Lim Geunbae
Published: May 2008

A micro-viscometer is designed for real-time measurement on the viscosity change of biomaterial including DNA or RNA, etc. It is composed of two chambers and several micro-channels connecting between them. Each chamber has a PZT unimorph membrane for generating and sensing the sound waves. Namely, one is regarded as an actuator, the other as a sensor. Micro-channels, which have the large attenuation of acoustic waves caused by wall effect, are applied to the micro-viscometer for increasing viscosity effect. When the actuator is driven at a resonance frequency under the condition of continuous flowing of liquid through an inlet/outlet hole, the sensor can detect the amplitude differences caused by viscosity change. Therefore, it is possible to measure the viscosity change in real time by detecting the signal change of sensor. The micro-viscometer can be also applied to the integration kit such as LOC (Lab-On a Chip) to detect whether DNA is amplified by micro-PCR (Polymerase Chain Reaction) and it will give a first opportunity for experimentally evaluating the viscosity effect on the propagation of acoustic waves in micro-channel. [Research supported by MRCnd of DAPA]
Design, fabrication and characterisation of piezoelectric micromachined ultrasonic transducers
Authors: Hladky-Hennion Anne-Christine , Ekeom Didace , Duval Fabrice , Cattan Eric
Published: May 2008

Micro-machined ultrasonic transducers (MUT) are investigated for phased arrays in high frequency acoustic imaging to overcome resolution and frequency limits of bulk PZT transducers currently used. The advantage of structures on silicon substrate is that transducers could be integrated with the electronics of the system. From a design point of view, finite element (FEM) codes are commonly used to model MUT, but to take into account the fluid surrounding the device radiation, scattering and the inter-mutual acoustic influence of the MUT arrays cells - the boundary element method (BEM) coupled with the finite element method is advantageously used. This paper describes the design, the fabrication and the characterisation of bending mode circular piezoelectric membranes, with operating frequency around 10 MHz. The devices are based on a PZT (lead zirconate titanate) film 1 μm thick supported by a membrane of polysilicon, 2 μm thick and SiO2, 500 nm thick. The PZT thin film was deposited following a sol-gel route. Fully-supported membranes as well as suspended cells are considered with a view to increase the resonant frequency and decrease the cross coupling between cells.
Capacitive micromachined ultrasonic transducers for generation of highly directional sound with a parametric array
Authors: Wygant Ira O. , Kupnik Mario , Windsor Jeffry C. , Wright Wayne M. , Wochner Mark S. , Yaralioglu Goksen G. , Hamilton Mark F. , Khuri-Yakub Butrus (pierre) T.
Published: May 2008

Capacitive micromachined ultrasonic transducers (CMUTs) with vacuum-sealed cavities have been fabricated and used to project directional sound using parametric arrays. The wafer bonding approach used to fabricate the CMUTs provides good control over device dimensions, a single-crystal silicon membrane that has predictable mechanical properties, and the capability to fabricate CMUTs with large-diameter membranes and deep cavities. The fabricated CMUTs are about 8 cm in diameter and comprise 284 circular membranes, each 4 mm in diameter. Testing of CMUTs with 40-μm and 60-μm-thick membranes shows they have center frequencies of 46 kHz and 55 kHz and 3-dB bandwidths of 1.9 kHz and 5.3 kHz, respectively. With application of DC bias voltages of 380 V and 350 V and an AC excitation of 200 V peak-to-peak, the devices generate effective source levels of 139 dB and 131 dB (re 20 μPa), respectively. We used the CMUT design with a 60-μm-thick membrane to produce 5 kHz sound at 3 m with a 6-dB beamwidth of 8.7 deg and a sound pressure level of 58 dB. The results demonstrate that large-area CMUTs, which produce high pressure ultrasound, can be fabricated for transmitting directional sound with parametric arrays. [Work supported by DARPA.]
Wafer bonded, local oxidation defined, capacitor micromachined ultrasonic transducers for medical applications
Authors: Khuri-Yakub Butrus (pierre) T. , Park Kwan Kyu , Lee Hyunjoo Jenny , Kupnik Mario , Oralkan Omer
Published: May 2008

We present a technology for making capacitive micromachined ultrasonic transducers (CMUTs) that is based on direct wafer bonding of silicon on insulator wafer (SOI), and where the vertical dimensions and geometry of the CMUT are defined by local oxidation (LOCOS). The advantages of this approach for making CMUTs is the excellent control, no only over the membrane properties, but also over the shape and dimensions of the cavity. We demonstrated the ability to make devices with cavities in the 10s of nanometer range which enables devices up to a frequency of 100 MHz. The devices exhibit reduced charging where we measure a voltage shift of 0.03 V for devices cycled in and out of collapse at 50 V. The devices also have reduced parasitic capacitance as thicker oxides are grown in the regions of the SOI bond to the membrane. These are typically the regions that contribute most to the parasitic capacitance. Finally, because of the reduced charging, it is possible to operate these devices in and out of collapse which results in higher output pressure than devices operating in conventional mode. Hence, these CMUTs are much more predictable and reproducible in their operation and performance.
Acoustic microelectromechanical viscometer
Authors: Ballato Arthur
Published: May 2008

Current dynamic techniques for measuring fluid shear viscosities using quartz, or other piezoelectrics, rely on the resonator surface being exposed to a measurand bath whose extent greatly exceeds the penetration depth of the evanescent shear mode excited by the active element. This configuration allows the effect of the loading parameters to be expressed concisely. Perturbation of the electrical equivalent circuit parameters of the resonator by the fluid loading permits calculation of the mass density - shear viscosity product. In this paper, we explore the interesting, albeit more complicated situation where the separation between the resonator and a confining wall is less than the penetration depth of the fluid occupying the intervening region. It turns out that the resonator perturbation in this case is a sensitive function of the separation. This important fact permits extreme miniaturization, since for gases between 200K and 400K, pressures between 0.01 to 100 atm, and frequencies between 10 MHz and 1 GHz, the penetration depth varies from micrometers to nanometers. Variations in the spacing is effected by using a second, nonresonant piezoelectric as the wall. Micro-electro-mechanics (MEMS) versions of viscometers and associated types of fluid sensors are thereby enabled.
Thin Film Piezoelectric MEMs Devices
Authors: Dr. Klee Mareike , Boots Henk , Kumar Biju , Keur Wilco , De Wild Marco , Dirksen Peter , Reimann Klaus , Wunnicke Olaf , Renders Christel , Van Esch Harry , Van Heesch Chris , Schmitz Georg , Mienkina Martin , Mleczko Michal
Published: May 2008

Thin film piezoelectric devices, processed in Si-related processes, are attractive for ultrasound transducers and piezoelectric switches. Thin film ultrasound transducer enable large bandwidth (> 100%), high frequency operation. In piezoelectric micromachined ultrasonic transducers (PMUTs) the ultrasonic waves are generated by flexural motion of the membrane, which is coupled to strain in the piezoelectric film. We have investigated the piezoelectric properties of thin films for ultrasound transducers and piezoelectric switches. Thin film piezoelectric ultrasound transducers as well as piezoelectric switches have been designed, processed and characterized. Thin film piezoelectric devices with excellent quality and reliability have been realized.
Reproducibity and life duration assessment of cMUT transducers
Authors: Meynier Cyril , Certon Dominique , Teston Franck , Ferin Guillaume
Published: May 2008

Cmut-based transducers are often expected to be superior in terms of reproducibility to piezoelectric transducers due to the use of microelectronic technology instead of more traditional machining techniques. During the conventional (sacrificial-layer based) production process of cmut transducers, various process steps can display inhomogenities and uncertainty in flow rate, temperature profile, stochiometry, or other aspects, resulting in variations in layers thicknesses, gap height, and material properties, each having an impact on transducer performances. In this study, we choose to use impedance measurement technique as evaluation tool for the stability of the properties of cmut transducers. A large number of cMUT transducers with the same design, were characterized, allowing to compare their properties from wafer to wafer, and according to their position of origin in the wafer. The resistance of cmut transducers to temperature cycling was also investigated, using impedance and optical measurements control before and after a 3-days +60/-20°c test. The reliability was tested under a long-duration electroacoustic measurement, where a cMUT transducer was submitted to periodic large amplitude excitation, and its pulse-echo response recorded for several hours.
Observing a chameleon: How to bridge a gap between the voice training and its scientific description
Authors: Ross Jaan , Vurma Allan
Published: May 2008

An overview of the authors' research on perception and production of singing voice as well as on the methods of voice training is presented. In the first study, a correlation was found for a group of voice students between the duration of training and the strength of the singer's formant, while the tone quality estimates were not significantly higher for students with longer practice years. In the second study we investigated possible acoustical correlates of the 'forward'/'backward' placing of a voice. A 'forward' placed voice may have higher F1, F2 and/or the singer's formant frequencies as well as a higher level of the singer's formant. In the third study we investigated the intonation accuracy in a cappella performance. There are considerable inter-individual differences between performers as to their adjustment of pitch level. The stability of intonation varies significantly both within a single rendition of the vocal exercise as well as between its consecutive renditions. There is a positive correlation between the deviation of a melodic interval from its equally tempered standard value and the number of out-of-tune judgments by the listeners. The dispersion of out-of-tune judgments is considerable, which suggests that listeners might have adopted different criteria for intonation accuracy.
Singing out of tune: Disturbances of vocal performance in the general population
Authors: Dalla Bella Simone
Published: May 2008

Acoustical methods can provide a reliable and objective estimate of singing proficiency in the general population, in terms of pitch and temporal accuracy (e.g., Dalla Bella, Giguère, & Peretz, 2007). The majority, when asked to sing a well-known song at a slow tempo, are as proficient as professional singers. Nonetheless, some nonmusicians exhibit poor singing. This deficit is mostly limited to the pitch domain and sometimes is not accompanied by impaired perception. More recently singing proficiency was examined in nonmusicians with tasks extending beyond singing familiar melodies. Forty participants imitated single pitches, intervals, and short melodies; in addition, participants sung three well-known melodies at a spontaneous tempo and at a fixed slow tempo. Additional tasks (e.g., Montreal Battery of the Evaluation of Amusia) were carried out to assess participants' perceptual abilities. Acoustical analyses of vocal performance revealed that the majority of nonmusicians sung in tune and in time, thus confirming previous findings. Still, various patterns of poor singing emerged from the analyses of pitch and time accuracy (e.g., poor pitch singing with or without perceptual deficits). The relationship between perception and performance mechanisms in vocal production will be discussed.
Sound radiation from annular jet ducts with impedance walls
Authors: Oliveira João M.
Published: May 2008

An analytical model for sound radiation from a semi-infinite annular duct with cylindrical infinite centre section and carrying a jet issuing into an uniform mean flow is presented. The interior of the outer wall of the duct is allowed to have an acoustic impedance. This is an extension to a recent model where only rigid walls were considered. The unstable cylindrical vortex layer attached to the edge of the duct, between the jet and the uniform mean flow, is considered. The geometry considered aims to model a turbofan exhaust, where sound generated at the inlet propagates along the annular duct and refracts through the bypass jet before radiating into the far field. In this paper the effect of the acoustic impedance of the duct outer wall on the radiated acoustic field is studied.