bluuebunny/crossref_metadata_2025 huggingface dataset:
Prosodic features and evaluation of pitch controllable electrolarynx
Authors: Koike Minako , Horiguchi Satoshi , Kasuya Hideki , Kikuchi Yoshinobu , Suzuki Makihiko , Okamoto Makito
Published: October 2011

The prosodic features and perceptual evaluation of an electrolarynx (EL) with pitch-control function were examined. We previously constructed a prototype electrolarynx of which F0 (hereafter “pitch”) can be adjusted by up-down or left-right thumb movement, and it was recently developed into a commercial product (Yourtone II, manufactured by DENCOM). Users can choose the pitch-fixed type with jitter (PF-EL) or the pitch-controllable type without jitter (PC-EL). One laryngectomized male speaker, who was an EL user and whose mother tongue was Japanese, served as the subject. He practiced controlling the pitch of PC-EL in Japanese (Tokyo dialect) for two weeks, and then his utterances when using PF-EL and PC-EL were recorded. Twenty normal listeners evaluated his EL speech tokens and were asked to rate on a visual analog scale how close the speech tokens were to normal speech. The results indicated that although the pitch range of PC-EL was narrower than that of normal speech and the production of Tokyo-dialect Japanese was not perfect, most of the PC-EL speech was rated more highly than PF-EL speech. [Work supported by KAKENHI (20500163 and 22500147).]
An additive blending sound presentation system with air and bone conducted sound
Authors: Itoh Kenzo
Published: October 2011

The sound of our voice reaches the inner ear by two paths: the first being air and the second being sound conducted by bones. When you speak, what you hear as your voice is the blending of two signals: one signal comes from the auditory canal and the other signal comes from bone conduction. This paper proposes a new sound presentation system with an additive blending effect with air and bone conducted signals. The system is composed of normal headphones and/plus a bone conduction transducer. The sound quality is evaluated by subjective tests using three kinds of musical sources: Piano, Vocal, and Orchestra. Two experimental conditions are used. One condition is normal headphones as air only (AIR), and the other is normal headphones and a bone conduction transducer simultaneously and in phase (BONE). The subjects select the better quality after comparing AIR and BONE conditions. The result of the experiment shows that the most subjects chose BONE. The proposed system can be used for aged persons or persons with hearing loss.
A comparative analysis of numerical optimization algorithm for array pattern synthesis
Authors: Wang Yingmin , Wei Xiao , Wang Yucai
Published: October 2011

The problem of array pattern synthesis with desired shapes has received much attention over years. There is a number of intelligent optimization methods that were adopted for pattern synthesis, and to some content, several successful design cases are reported. In this paper, based on a special sensor array, a comparative study of those methods is given. Those methods include simulated annealing, genetic technique, and adaptive searching procedures. The effectiveness of the algorithms is demonstrated by the sidelobe level and the width of the main beam. For a given array, those techniques are investigated on their convergence speed and residue error energy. A set of design results are given in details and conclusions are included.
Analysis of truncation and sampling errors in the spherical harmonic representation of soundfields
Authors: Brown Stefanie , Sen Deep
Published: October 2011

The use of microphone arrays to record soundfields for subsequent immersive reproduction, real time or off-line beamforming applications are becoming increasingly prevalent. The representation and analysis of such recorded soundfields using finite-order spherical harmonic coefficients is elegant and has a number of advantages. The focus of this paper is to quantify the accuracy of such a representation which is limited by errors introduced by several types of non-idealities: manufacturing non-idealities of the array such as microphone positional errors, coupling between microphones, etc.; physical non-idealities due to the discrete spatial sampling of the soundfield which introduces spatial aliasing and the inherent truncation of the modal representation of the soundfield to a finite order; and mathematical errors due to the computational technique used to derive the modal coefficients. This paper investigates the latter two classes of errors and quantifies the significant advantages in accuracy achievable when the physical structure of the microphone array allows the use of the orthogonal properties of the spherical harmonic basis functions to extract the modal coefficients. In addition, we extend previously published analysis of the truncation error, which was limited to incident plane waves, to spherical waves.
Analysis on novel tangible acoustic interfaces approaches and new thoughts
Authors: Wang Xu , Yang Hong Jun
Published: October 2011

To solve the problems in novel tangible acoustic interfaces approaches [time delay of arrival (TDOA) and location pattern match (LPM)], a new method (which is amplify contrast method) of setting threshold so as to determine the arrival point will be applied, and three new thoughts on LPM, which are improved LPM, time match, and amplitude attenuation match, would be proposed. Traditional TDOA is based on measuring time difference and wave velocity. Traditional LPM is based on time reversal theory and cross correlation. New thoughts are based on amplification on signal, classification of signal source, match time, and uniqueness of damping. Amplify contrast method improves the accuracy of determining the arrival point.
Validation of statistical inference using towed source data
Authors: Stotts Steven A. , Koch Robert A. , Sagers Jason D.
Published: October 2011

An idealized concept of inversion modeling assumes for a given model that environmental and geometrical parameter values can be determined to match similar measured parameter values. In practice, data-model mismatch is inherent due to noise and the inability of the model to provide a one-to-one correspondence with the real environment. Several approaches have been devised to apply statistical inference to the inversion geoacoustic parameter values, but the uncertainties calculated for these values cannot be validated directly with ground truth measurements. However, tones with calibrated source levels in data received from a towed source can provide a direct assessment of whether the estimated source level uncertainties encompass the actual error in the estimated source levels. Examples from the Shallow Water '06 experiment will be discussed to illustrate the procedure.
Inversion of shear properties in ocean sediments from numerical Scholte wave
Authors: Cao Zhengliang , Dong Hefeng
Published: October 2011

Shear properties in marine environment are important to be measured for the stability of sediments, the tomography of shallow layers, and the conversion of acoustic energy from water-borne into sea bottom. Although surface wave methods are widely used to determine the shear wave velocity profiles at sites, inversion methods of shear attenuation have to be tackled with other difficult problems. So, an inversion method by dispersion curves of surface wave is developed and tested with the numerical Scholte wave data. The method includes three steps: extract of dispersion curves from data, calculation of forward dispersion model, and linear inversion by match of them. To simultaneously estimate dispersion curve of velocity and attenuation, Prony's method is applied for multi-modes of surface wave. Based on the methods of finding complex roots, forward model of dispersion curves is calculated with so accuracy as to get reasonable Jacoby of inversion. Different to inversion of shear velocity, the effect of spread loss is considered and investigated for Scholte wave. The performance of inversion shear wave velocity and attenuation profiles in the upper sediment layers is also examined for multi-mode dispersion curves.
Efficient acoustic uncertainty estimation for uncertain source depth
Authors: James Kevin R. , Dowling David R.
Published: October 2011

Uncertainty in source depth is a prevalent source of uncertainty in underwater acoustic measurements and predictions. This uncertainty can arise from limited information about a source, or the movement of a source between measurement intervals, such as the bobbing of a ship's propeller near the ocean surface. This presentation describes the effect of source depth uncertainty on transmission loss predictions at frequencies from a few hundred hertz to a few kilo-hertz in both range-independent and range-dependent environments, as well as the relative contribution of source depth uncertainty compared to other likely sources of environmental uncertainty. Several approaches to estimating the resulting transmission loss uncertainty are considered, including direct simulation with Taylor series approximations, the field-shifting method, polynomial chaos expansions, and a reciprocity-based solution. In particular, it will be shown that a reciprocity-based algorithm provides exact results in range-independent environments with a single field calculation but can require additional calculations to obtain transmission loss versus range information in a range-dependent environment. Strategies for limiting the computational effort and possibilities for implementing the reciprocity approach within the US Navy's existing transmission loss uncertainty estimation technique, the Uncertainty Band algorithm, are presented. [Work sponsored by the Office of Naval Research, Code 322OA.]
Choir hearing responses: Rehearsal versus performance configurations
Authors: Sweitzer Glenn E.
Published: October 2011

Choir responses to hearing (parts) in a rehearsal room are compared with those for its associated performance stage. Anonymous responses from each choir member are gathered via a hand-held battery-operated device that enables scaled responses (5). The protocol is administered in the rehearsal room for the choir configured by part versus mixed, in straight rows versus curved rows, standing on a flat floor versus risers, and facing a diffusing wall versus an adjustable absorptive wall. This protocol is repeated on the performance stage, except that the choir faces the audience only. Preliminary results suggest that responses vary widely by configuration and suggest that choir response has been largely ignored in the design of and operation of choir rehearsal and performance facilities.
American Institute of Architects Continuing Education System Provider Registration and Reporting Requirements
Authors: Brooks Bennett M.
Published: October 2011

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects. The TCAA short course is called “Architectural Acoustics” and attendance at this 1-h long course can earn an architect one continuing education unit with HSW Credit (Health Safety and Welfare). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork, so that AIA members may receive credit for the course. Also, the manner in which the course is given is dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course.
Behavioral audiogram of the giant panda (Ailuropoda melanoleuca): Preliminary results
Authors: Owen Megan A. , Keating Jennifer L. , Denes Samuel L. , Hawk Kathy , Boroski Juli , Fiore Angela , Swaisgood Ronald R.
Published: October 2011

We used behavioral techniques to assess the hearing sensitivity of four, critically endangered, giant pandas at the San Diego Zoo. Study subjects included one adult male (age 19), two adult females (ages 5 and 19), and one sub-adult female (age 3). We used a down-up staircase presentation order and a go/no-go response paradigm and thus far have measured hearing thresholds between 250 Hz and 31.5 kHz. Test stimuli were 500 ms shaped tones, and catch trials represented 30% of presentations. All subjects were trained using positive reinforcement. Preliminary results suggest that giant pandas have good hearing sensitivity between 8 and 14 kHz, and best sensitivity was centered at 12.5 kHz. Low frequency hearing sensitivity declined at 250 Hz for all subjects. All bears retained functional hearing at 31.5 kHz: the younger females could hear tones as low as 15 dB, and the adults could hear to 25 dB. Preliminary results suggest that panda hearing sensitivity is similar to that of other terrestrial carnivores studied to date. Hearing sensitivity data will enhance the understanding of how anthropogenic noise may impact both free-ranging and captive giant pandas.
Micromachining of acoustic transducers and arrays
Authors: Wang Zhihong , Zhang Xixiang , Wang Xianbin
Published: October 2011

Microelectromechanical systems (MEMS) technology has been used to fabricate miniature acoustic transducers for a variety of applications in different media and frequency ranges. The consistency in performance of individual transducer afforded by batch-fabrication also makes it feasible to employ MEMS transducer arrays in beam forming or beam steering technique. This paper will first introduce our own research work on micromachining of piezoelectric acoustic transducers, including sol–gel thin film piezoelectric microphone for audio application; composite thick film piezoelectric micromachined ultrasonic transducer array for biomedical imaging; and transducer arrays fabricated by Si-PZT bonding technology for hydrophone and audio beam applications. The preliminary results on receiving and transmitting performance of the fabricated transducers and arrays will also be reported. In addition, a scanning acousto-optic microscope, which uses a single micromachined acousto-optic sensor and interferometry, will also be introduced. With this technique, it is possible to map a spatial sound field distribution at micrometer resolution.
A micro-machined microphone based on field-effect-transistor and electrets
Authors: Shin Kumjae , Je Yub , Lee Haksue , West James Edward , Moon Wonkyu
Published: October 2011

Micro-machined microphones are attracting attention of industry because of their benefit of size over conventional ones. Since most of micro-machined microphones are capacitive sensors, the sizes of their electrodes determine the low frequency noise level that increases with inverse of frequency (1/f). Therefore, the size of microphone itself becomes larger than one that can be fabricated. Here, we introduce a micro-machined microphone that can overcome the limit of capacitive microphones. The proposed microphone is composed of a field-effect-transistor (FET) and an electret. The difference between the conventional electret capacitive microphones and the proposed microphone may be the transduction mechanism: The change in the position of an electret causes the change in electric field on the gate of FET. Compared with capacitive transduction, the resistive channel of FET can be designed to have low sensor impedance, and subsequently have low impedance at low frequency. To make experimental specimen, FET onto membrane and electret was fabricated with conventional metal-oxide-semiconductor fabrication process and micromachining process, respectively. The FET membrane chip and the electret chip were assembled. Simple current to voltage converter was applied as a pre-amplifier. Its feasibility to apply low frequency acoustic sensor will be proved by simulation and experimental results.
The piezoelectric micromachined ultrasonic transducer arrays as a high-intensity sound generator: An experimental analysis
Authors: Je Yub , Lee Haksue , Moon Wonkyu
Published: October 2011

High-intensity sound generation in air with high efficiency is usually difficult, since the acoustic impedance of air is generally much smaller than that of the transducers. In an earlier study by [H. Lee etal., J. Acoust. Soc. Am. 125, 1879-1893 (2009)], the potential for high-efficiency sound generation of a piezoelectric micromachined ultrasonic transducer (pMUT) was examined theoretically and experimentally. A thin-film transducer such as pMUT can generate sound with improved mechano-acoustic efficiency since the internal mechanical impedance of the thin-film structure can be reduced. The highly efficient characteristics of a single pMUT, however, cannot easily be used to yield high-intensity sound from pMUT array, due to variations between units in membrane size, driving voltage, and acoustic loading. In this work, a pMUT array consisting of efficient PZT uni-morph elements was designed and fabricated. The unit-to-unit variations of the pMUT array are analyzed by measuring velocity amplitude and phase of each unit transducer. The result shows that the radiated sound from pMUT array is greatly reduced due to the unit-to-unit variations of the pMUT. To eliminate the problems, uniformity control of fabrication process, optimal design of electrode pattern, and alignment method of an array pattern are considered for high-intensity sound generation.
Hands-on acoustics for public school students
Authors: Hansen Uwe J. , Adams Wendy
Published: October 2011

Since the appointment of an Education Coordinator, the hands-on equipment purchased by ASA, as well as material donated by various Science Education companies, has been sorted and prepared for safe and easy shipping. It is ready for continuing use at the ASA semiannual meetings and within limits will also be accessible for use by ASA members in connection with various events at locations throughout the country. The general hands-on philosophy and a number of the experiments included in the material will be discussed and demonstrated. A detailed description of the individual experiments, as presented in a student hand-out, will also be distributed. The “Acoustics Activity Kit for Teachers” will also be demonstrated and discussed.
The standards process from the perspective of a government scientist
Authors: Konheim Arnold G.
Published: October 2011

Through its operating administrations, the U.S. Department of Transportation issues regulations covering the safety, security, health, and environmental protection of all modes of transportation. Many of these regulations incorporate consensus standards as required under the National Technology Transfer and Advancement Act of 1995, which directs federal agencies to generally use standards developed by voluntary consensus bodies. Particular examples of the role of consensus standards in DOT regulations are discussed in this presentation.
International standards development and the U.S. Technical Advisory Group process
Authors: Blaeser Susan B.
Published: October 2011

As industry becomes increasingly global the importance of international standards increases, too. How can U.S. companies, government agencies, and other organizations ensure that their voices are heard and their interests are protected? The U.S. Technical Advisory Group (U.S. TAG) provides the only avenue for U.S. stakeholders to provide input to technical committees in the International Organization for Standardization and the International Electrotechnical Commission. The Acoustic Society of America currently administers nine of these U.S. TAGs. This paper discusses TAG membership and participation in international standards development.
Bone and/or tissue conducted noise: Implications for advanced hearing protection
Authors: Gallagher Hilary L. , Theis Melissa A. , McKinley Richard L
Published: October 2011

Military personnel working in various high noise environments may be exposed to continuous noise levels reaching 150 dB. At those levels, bone and tissue conduction pathways become the dominate pathway for sound transmission to the cochlea. Accordingly, hearing protection devices designed to attenuate noise transmitted via air conduction pathways may not be sufficient for meeting hearing conservation requirements. The goal of adequately protecting personnel in these types of environments requires a better understanding of the bone and/or tissue conduction flanking pathways, the susceptibility of the cochlea to bone and tissue conducted energy, and the accompanying mitigation strategies. This experiment investigated the linearity of air conducted noise to the transmission of bone, tissue, and bone/tissue conducted noise. Specially designed bone and tissue conduction drivers, which primarily isolate and excite the respective desired pathways, were used to conduct a loudness matching study. Preliminary findings from this study will be discussed, as well as the implications for development of more effective hearing protection and potential needs for creating new safety requirements based on bone and tissue conducted stimulation. [Work sponsored by AFOSR.]
Speech rhythm in Akan/Twi: A preliminary experiment
Authors: Anderson Jonathan C.
Published: October 2011

This study explores the rhythmic timing patterns of Akan/Twi, a West African tone language thought to be syllable-timed, using the Speech Cycling Task (Cummins & Port, 1998; Port, 2003, 2007; Tajima & Port, 2003). How rhythm appears in tone languages without stress/accent is poorly understood. In the Speech Cycling Task, speakers were expected to place prominent elements within rhythmic modes, where specific syllables are pronounced more frequently in certain temporal regions. To uncover which syllables are considered rhythmically prominent, a previous tapping experiment (Darwin & Donovan, 1980; Donovan & Darwin, 1979; Purvis, 2009) was used in which subjects displayed entrainment between tapped beats and specific syllables (akin to stress-timing), rather than beat entrainment with all syllables. Prominent elements should also be resistant to temporal displacement when syllables are inserted between them and temporal compensation should occur when syllables can be deleted. The data included 20 phrases ranging from 4 to 8 syllables in length and four tone melodies (H, L, HL, and LH) repeated at varying rates. Results suggest subjects prefer certain rhythmic modes and that displacement and compensation occur such that rhythmic patterns change. Implications for the stress-timing/syllable-timing dichotomy and how tonal melodies affect rhythmic patterns are discussed.
The sound of resonance
Authors: Hart Katherine , Neilsen Tracianne B.
Published: October 2011

A basic understanding of the production of sound waves can be obtained by studying standing waves and resonance frequencies. A vibrating string will settle into a steady, standing wave pattern when it is driven at one of its resonance frequencies. The resonance frequencies depend on the string's length and the tension applied to the string. Similarly the resonance frequencies of tubes are determined by the tube's length and whether the ends are open or closed. In a series of hands-on demos, we will explore the factors that influence the creation of standing waves by exciting the resonances of strings, tubes, rods, a metal plate, slinky, and a wine glass. These simple models provide insight into how musical instruments produce sound.
Defining the scope of soundscape studies and design methods
Authors: Siebein Gary W.
Published: October 2011

One important goal of soundscape studies is to develop methods that architects, urban designers, planners, landscape architects, and others involved with the design of the indoor and outdoor physical environment can be implement as part of their work. As such the role of design is an inherent aspect of soundscape studies. Design of the physical environment, especially its sonic qualities, is similar to the composing and orchestrating of a piece of music. This paper explores the translation of soundscape theories into physical design concepts through a review of the seminal literature of Shafer and Truax and the systems ecology models of Odum and Brown. The use of physical design elements to create sonic niches for specific acoustic events to occur within that are defined in location and time is used as a technique to develop local sonic attributes within soundscapes. Advanced modeling and simulation techniques; long and short term acoustical measurements that reflect the way sounds are heard by people; interviews, focus group discussions, and questionnaires given to participants in the soundscape to explore the ways people understand sounds in their context; and transformations of the data into physical acoustical interventions are important parts of the process.
Acoustic monitoring of fish movements across multiple spatial and temporal scales
Authors: Papastamatiou Yannis P.
Published: October 2011

Understanding the movements of fishes is important for understanding ecological interactions, conservation, and fisheries management. One of the key techniques used to quantify fish movements is acoustic telemetry. Fish can either be actively tracked (where the fish is continuously followed) or be remotely monitored using an array of underwater listening stations (passive telemetry). Ultimately, an understanding of fish movements is required over multiple spatial and temporal scales, which requires the use of several tools. The specific tools used will also vary based on the species being studied, which can range from small reef fishes to pelagic sharks. The use of telemetry in fish movement studies will be reviewed and examples of what sort of questions may be answered using these tools will be given. Future advances in both the tools utilized and the analytical techniques used to interpret data will also be discussed.
Passive acoustic fish location with a 3-D fixed array
Authors: Rountree Rodney , Sinelnikov Yegor , Sutin Alexander
Published: October 2011

There is a strong need for improved sound source localization software for use by scientist interested in conducting passive acoustic surveys of marine and aquatic habitats where most biological sounds are currently unidentified. Fish sounds are typically low frequency (50–1200 Hz), narrow band, knock trains, short duration grunts, or tones, and can be repeating or irregular. These characteristics together with typically fuzzy signal onset, noisy environmental conditions, and shallow depths often make source localization challenging. We used small 3-D arrays of six hydrophones placed in a fixed-frame square diamond configuration to collect known and unidentified fish sounds for testing from a variety of shallow marine and freshwater habitats. The various methods of sound source localization based on measurements of Differences in Time of Arrival (DTOA) at various hydrophones were investigated, including cross-correlation, first pulse arrival, and phase measurement of tonal components in the fish signal. The most accurate DTOA measurements were obtained using cross-correlation with the phase transform (PHAT) methods. The various algorithms of source localization based on DTOA were considered and MATLAB program for these algorithms were developed. Our goal is to develop publically available software realizing the optimal method of DTOA measurements and source localization.
Ocean conditions and occurrence of cetacean species near Pt. Sur, California, in 2008–2010
Authors: Margolina Tetyana , Stimpert Alison K. , Joseph John E. , Collins Curtis A. , Miller Christopher W.
Published: October 2011

The central California region of the California Current system is characterized by rich marine life and highly variable physical and biological ocean conditions. Here, patterns of marine mammal occurrence near Point Sur are analyzed and linked to seasonal and larger scale variability of the California Current system. A summary of marine mammal vocalizations was created by scanning passive acoustic recordings in the 10–100 kHz frequency band acquired with High-frequency Acoustic Recording Packages (HARPs) deployed at depth of approximately 840 m from August 2008–November 2010. Calls of detected baleen and toothed whales were presented as occurrence time diagrams. To characterize the ocean conditions of the California Current system during this time period, various datasets were used including current meter data collected at Sur Ridge and satellite-derived information on chlorophyll-a concentration (MODIS), temperature (AVHRR), and sea surface height anomalies (AVISO SSH products). Data series of chlorophyll concentrations were used to examine possible changes in the ocean physical and biological state off central California in response to El Niño/Southern Oscillation processes. Correlations between patterns of cetacean occurrence and variability of oceanographic conditions are analyzed and discussed. [Research supported by US Navy CNO(N45).]
Acoustic and thermal monitoring of temperate anuran populations
Authors: Marquez Rafael , Llusia Diego , Beltrán Juan Francisco
Published: October 2011

The results of multi-year acoustic monitoring using automated recording systems (ARS) of the calling activity of two populations per species of five species of anurans from the Iberian peninsula are reported: two species of tree frogs (Hyla) and three species of midwife toads (Alytes), with populations of each species being located at the thermal extremes (coldest vs. hottest) of their distribution. We also report one instance where ARS systems contributed to the recording of a previously undescribed species call, the Moroccan midwife toad. We report methodological procedures such as calculation of the effective area of the recording station, temperature-specific phenological information, and a comparative analysis of environmental predictors of calling activity. Implications for amphibian monitoring and conservation are discussed.
Monitoring white seabass spawning sounds using a long-term acoustic recording system
Authors: Aalbers Scott A. , Sepulveda Chugey A.
Published: October 2011

The white seabass (Atractoscion nobilis) is an economically important member of the family Sciaenidae that generates a series of distinct low-frequency sounds during spawning. Long-term acoustic recorders (LARS; Loggerhead Instruments) were moored to the seafloor at three sites along the southern California coastline to monitor white seabass sound production. LARS were programmed to record ambient underwater sounds at a sampling rate of 8820 Hz during periods of peak spawning activity (+/− 1 h sunset) from March through July of 2007–2011. White seabass spawning signals were detected at all three sites and verified through the concurrent collection of gravid individuals. Heightened white seabass sound production was documented during May and June, in conjunction with increasing water temperatures and photoperiod. Detection rates were highly variable between adjacent sites and over consecutive seasons, suggesting that spawning activity and site fidelity is influenced by oceanographic conditions. Although additional work is necessary to determine optimal spawning habitats and environmental conditions, this study confirms the utility of a bioacoustic approach to non-invasively identify white seabass spawning periods and locations.
Bifrequency excitation for extracorporeal ultrasound thrombolysis
Authors: Gilles Bruno , Saletes Izella , Dhahbi Mamdouh , Ben Chiekh Maher , Béra Jean-Christophe , Salomir Rares
Published: October 2011

A bifrequency excitation consisting of two neighboring frequency components can reduce intensities needed to achieve strong inertial cavitation activities. We present in-vitro experimental results aiming at testing such a bifrequency excitation for extracorporeal ultrasound thrombolysis. In a first set of experiments, human blood clots were inserted in small tubes filled with saline and placed at the focus of a piezoelectric transducer. The efficiencies of mono- (550 kHZ) and bifrequency (535 and 565 kHz) excitations were compared for (spta) intensities ranging from 50 to 160 W/cm2, and a passive recording of the cavitation activity was performed during treatment. A modified setup enabled to measure the size distribution of the debris resulting from thrombolysis experiments realized under flow. A comparison of the spatial temperature distribution for each type of excitation was performed in another set of experiments using MR temperature imaging. Under the conditions of the experiments, 80% of thrombolysis was achieved with a monofrequency intensity of 150 W/cm2, while 80 W/cm2 were sufficient with a bifrequency excitation. Mean debris size was reduced by the use of a bifrequency excitation, and MR temperature imaging showed that, for a given intensity, the spatial temperature distributions are the same for both types of excitation.
Ultrasound-enhanced thrombolysis in porcine clots in a flow system
Authors: Ammi Azzdine Y. , Zhao Yan , Xie Aris , Lindner Jonathan , Porter Thomas R. , Kaul Sanjiv
Published: October 2011

Ultrasound and ultrasound contrast agent microbubbles (UCAM) are able to mechanically induce clot reduction. The aim of the study was to demonstrate the efficacy of various ultrasound conditions to enhanced thrombolysis in porcine clots inside a flow system. Clots were formed by infusing 4.1 ml of blood in transfer pipets. The pipets contained Dacron grafts to anchor the clot and initiated its formation. A 14-gage needle was placed at the center of the pipet and removed after clot formation to allow flow inside the clot. The clots were treated for 20 min with ultrasound and homemade UCAM at a concentration of 107 microbubbles/ml (flow rate 0.9 ml/min). Thrombolysis was monitored using an ultrasound scanner in pulse inversion mode. Results show that the radiation force causes the microbubbles to be pushed against the inner clot wall and cavitation induced lysis. The portion of the clot closest to the transducer was not affected by the therapy as the microbubbles were pushed in the direction of propagation. Mechanical clot reduction was observed in real-time in a flow system at various acoustic settings.
Modifying a balanced armature speaker for energy harvesting applications
Authors: Vitt Nikolas T. , Thompson Stephen C.
Published: October 2011

Balanced armature transducers are produced in large quantity for use as miniature speakers in hearing aids and in-ear headsets. These devices are reciprocal and might be used as the generator in vibration energy harvesting. However, previous work has shown that, as manufactured, the speakers do not have sufficient vibration sensitivity to be directly used in this way. This paper explores a set of design modifications to increase the sensitivity to a useful level. Preference is given to modifications that require minimum investment in new manufacturing tooling.
The octoid modal vector projector
Authors: Butler Alexander L. , Butler John L.
Published: October 2011

The eight piston octoid transducer is a descendent of the three piston trioid and four piston astroid transducers. These transducers were developed for low frequency underwater sound applications where wide bandwidth and small volume is desirable. Magnified piston motion is achieved through attached leveraged shell action driven by radial piezoelectric stacks. This condition yields magnified piston displacement and lowered Qm through magnified loading on the piezoelectric stacks. The new octoid design concept was implemented on an eight stack power wheel modal transducer. And this new design has been used to significantly reduce the outer diameter for the same response or, alternatively, yield lower frequency response for the same diameter. Finite element model and measured results are presented for the power wheel with and without the octoid leveraging and the octoid transducer is also compared to the previous trioid and astroid transducers.
High power, broad bandwidth, compact, single crystal vector projector
Authors: Baird P. David , Powers James M. , Rodriquez Ivan A.
Published: October 2011

An approach to producing a high power, broad bandwidth, compact transducer with steerable super-directionality will be described. The design, utilizing high coupling coefficient PMN-PT single crystal material, will be compared to conventional transducers utilizing PZT ceramic. Performance predictions for transmit response, impedance, efficiency, power, volt-amperes, source level, and bandwidth will be provided.
Measurement and physical modelling of sound hole radiations of lutes
Authors: Pfeifle Florian
Published: October 2011

A structural feature that can be found in many string instruments is a hollow body with one or several sound holes. The sound radiated from these holes interacts with the sound radiation from the rest of the body and perceivably influences the timbre and the loudness of the instrument. In this work three non-European lutes with sound holes are measured: the Mauretanian ginbri, the West-African gunubri, and the Chinese ruan. All of these instruments have distinct cavity air modes and a measureable Helmholtz frequency. Each instrument is measured with a 11 × 11 microphone array and analyzed with a focus on the radiated spectrum and sound intensity of the hole(s). In a further step, the findings of the measurements are compared to a Finite Element model and incorporated into a real-time finite differences physical model of the ruan.
Tuning parameters of the Nigerian slit drum
Authors: Cannaday Ashley , Moore Thomas
Published: October 2011

The slit log drum, sometimes referred to as a “talking drum,” is an idiophone indigenous to many African and South Pacific cultures. It is made from a log that has been hollowed out through two square openings, which are separated by a solid piece of the wood. The solid piece is cut down the middle to produce two tabs that when struck produce pitches that are usually separated by a musical fifth. We report on an investigation of the tuning parameters of slit log drums from Nigeria using both numerical and analytical models. We conclude that the most efficient and effective method of tuning the drum is to carve the interior walls near the tabs so that they have different thicknesses, which is indeed is how the Nigerian artisans produce the two distinct pitches.
Mechanism of acoustic radiation from Supersonic Jets Impinging to Inclined Flat Plates
Authors: Tsutsumi Seiji , Nonomura Taku , Fujii Kozo , Nakanishi Yuta , Okamoto Koji , Teramoto Susumu
Published: October 2011

Acoustic wave radiated from supersonic cold jets impinging to inclined flat-plates is investigated numerically with the help of the experimental work. This type of acoustic generation is important for estimating and minimizing the acoustic loading of launch vehicle at lift-off. Through the study on the 45-degree-inclined flat plate located 5 D downstream from the nozzle exit, two noise sources are found to be generated due to the jet impingement: (1) interaction between the vortex of the jet shear-layer and the shock waves appearing at the jet impingement region and at the downstream region, (2) the Mach wave radiated from the large-scale vortex structure of the flow downstream of the plate. The former is similar to the broadband shock-associated noise. Those features are clearly confirmed by applying the proper orthogonal decomposition analysis to the numerical result. Prediction accuracy of 5 dB in far-field OASPL is obtained in the current numerical technique.
Statistical analysis of noise from solid rocket motors
Authors: Harper Stuart A. , Gee Kent L. , Giraud Jarom H. , Muhlestein Michael B.
Published: October 2011

In an effort to better understand the properties of rocket noise, the statistical properties of noise data from various-sized solid propellant rocket motors. Time waveform data sampled at 204.8 kHz using 6.35 and 3.18 mm microphones were collected near motors with nozzle exit diameters ranging from 0.13 to 1.22 m. Non-Gaussian features of the data have been explored by calculating estimates of the probability density functions of the data and various statistical moments, including skewness and kurtosis. This has been carried out for both the pressure waveform and its first order time difference to better understand the formation of acoustic shocks within the noise. The analysis shows greater similarity between the statistics for the pressure than for the time derivative estimates.
Two techniques for measurement of flow resistance
Authors: Mitchell Eric C. , Swaminathan Anand , Garrett Steven L. , Poese Matthew E.
Published: October 2011

The accurate measurement of flow resistance has many applications in acoustics. In our laboratory, it is particularly important for the characterization of materials used as regenerators in thermoacoustic refrigerators and for the quantification of leakage paths in complex assemblies. This presentation will describe two techniques for flow resistance measurements made at sufficiently low Reynolds numbers that the resistances measured for unidirectional flow are relevant to acoustic flows. One technique uses a “constant current generator” configuration to characterize stacked stainless steel screens and the other uses an Airpot® graphite piston in a glass cylinder to produce a constant pressure difference and accurate flow rate. Both techniques use air at atmospheric pressure as the test fluid. The constant current technique produces results that are consistent to ±3% for stacks of stainless steel screens that vary in thickness from 10 to 50 screens. The Airpot® technique can produce similar accuracy for flow resistances as large as 1010 Pa-sec/m3. [Work supported by the Applied Research Laboratory and the U.S. Department of Energy.]
Acoustic radiation torque of arbitrary shaped waves
Authors: Silva Glauber , Mitri Farid
Published: October 2011

In this work, a general expression of the acoustic radiation torque produced over an object by an arbitrary shaped beam is presented. The object is immersed in an inviscid fluid. To obtain the expression, the stress tensor of the angular momentum is integrated over a farfield virtual sphere, which encloses the object. The incident and scattered acoustic fields are represented through the partial wave expansion in the spherical coordinates. After performing the integration, the radiation torque is given in terms of the beam-shape and the scattering coefficients, which come from the incident and scattered partial wave series, respectively. The method is applied to compute the torque upon a fluid sphere by a vortex (first-order) Bessel beam in both on- and off-axis configurations. It is shown that the torque only arises on absorbing spheres. In this case, the angular acceleration and velocity are obtained from the torque. It is found that the angular acceleration may reverse its direction depending on the wave frequency. In conclusion, the presented theory might be useful for describing the particle dynamics of a sphere subjected to acoustic vortex beams.
Synchronization of ultrasonic thermoacoustic devices
Authors: Flitcroft Myra , Symko Orest G.
Published: October 2011

The development of ultrasonic thermoacoustic devices opens up a new field of applications, in particular where heat can be converted acoustically to electricity in small systems. The power level for applications can be raised by incorporating such devices into array configuration. Since the acoustic devices are self-sustained oscillators, their phase at onset for oscillation is unpredictable; they are triggered on by a random fluctuation. Hence, maximum power output will be achieved by synchronizing the elements of an array. This can be accomplished by suitable coupling between them. Results are presented on the in-phase synchronization of ultrasonic thermoacoustic prime movers at ∼23 kHz, acoustically coupled by means of an acoustic cavity. Each engine has an inner volume of ∼2.7 mm3. They were activated by means of separate wire heaters; the working fluid is air at one atmosphere. The demonstration of the synchronization of acoustic engines can be extended to many applications.
Photoacoustic spectrometer with a calculable cell constant for accurate absorption measurements of atmospheric aerosols and greenhouse gases
Authors: Gillis Keith A. , Hodges Joseph T.
Published: October 2011

A photoacoustic (PA) spectrometer for absolute optical absorption measurements of aerosols and greenhouse gases in ambient air has been developed. A theoretical analysis of the system in terms of the gas properties, continuous wave laser intensity modulation, and energy transfer relaxation rates will be discussed. The measured and predicted values for the PA system response differ by about 1%. The accuracy of the spectrometer is demonstrated by a probe of the absorption transitions of the A-band of O2 in atmospheric humid air using reference line-shape parameters and accounting for reduced conversion efficiency due to relaxation effects. These transitions also provide a convenient method to monitor the system stability in the field. Observed detection limits are 3.1 × 10−9 W·cm−1·Hz−1/2 for absorption by gases and 1.5 × 10−8 W·cm−1·Hz−1/2 for absorption by soot particles (limited by fluctuations in the aerosol concentration). The sensitivity of the instrument is demonstrated with measurements of the amplified absorption resulting from ultrathin (>5 nm), nonabsorbing coatings on nanoscale soot particles. Applications to real-time monitoring of CO2 concentration in ambient air and to measurements of the albedo of soot aerosols will be discussed. [Work is supported by NISTs Greenhouse Gas Measurements Program.]
One channel spatio-temporal inversion of acoustic wave in reverberant cavities
Authors: Matthieu Ruppin , Stefan Catheline , Philippe Roux
Published: October 2011

It has been recently shown that it was possible to optimally recover the Green functions from a complex wave field despite of a non-isotropic distribution of the noise sources. The method used is based on a particular use of the inverse filter (IF) formalism which is called the passive IF. Based on this formalism, we have investigated the possibility to control the spatio-temporal degrees of freedom in a reverberant cavity for the focusing of waves (active processes). The understanding of this phenomenon can be very useful in a lot of different applications like in acoustical imaging, seismology, or telecommunications. In the present work, the spatio-temporal focalization of ultrasounds in reverberant cavities is studied using medical arrays and water tanks. Through experiments, a complete spatio-temporal inversion is realized to synthesize optimized emitting signals. The result generalizes the focalization control over a spatial vector and during an arbitrary time window.
A computational model for evaluating the interaural disparities using coincidence detection
Authors: Bures Zbynek
Published: October 2011

In mammals, spatial hearing is supported by evaluation of two types of binaural disparities, interaural time difference (ITD) and interaural level difference (ILD), which is performed by auditory neurons in the superior olivary complex. Using a complex auditory model, which includes a binaural evaluation stage, the output of binaural neurons from medial and lateral superior olive is simulated and quantitatively compared with available experimental data. Both binaural disparities are evaluated using detection of coincidence of spikes arriving from the two channels: in case of ITD, the coincidence of two excitatory spikes is detected; in case of ILD, the coincidence of one excitatory and one inhibitory spike is detected. It is shown that using a physiologically realistic set of parameters, evaluation of both ITD and ILD based on coincidence detection is capable of reproducing the observed neuronal responses. Furthermore, the model is shown to qualitatively reproduce the just-noticeable differences of binaural parameters depending on frequency and intensity. [Work supported by the project “Podpora a individualni rozvoj perspektivnich akademickych pracovniku na VSPJ” at the College Of Polytechnics Jihlava.]