bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic cavitation and sonoluminescence
Authors: Matula Thomas J.
Published: July 2012

The violent collapse of a bubble in an acoustic field can lead to the emission of light, a phenomenon called sonoluminescence (SL). The study of sonoluminescence has led to refinements in understanding cavitation. This talk will focus on three areas of research in which the application of sonoluminescence is used to investigate cavitation: (1) In the field of single-bubble SL, techniques have been improved to study the dynamical motion of the bubble and, with comparisons to SL, models of the bubble dynamics have been refined. In particular, thermal conduction and the trapping of water vapor during the bubble collapse contribute significantly to the internal temperatures and to the dynamics of the cavitation bubble. (2) In lithotripsy, intense shock waves generate cavitation fields which play a role in kidney stone communition. In vitro studies have shown that SL can be correlated with a bubble’s expansion and collapse within the field. (3) In sonochemistry, high-intensity ultrasound is used to initiate or enhance chemical reactions. SL is often observed under these conditions, and in some cases, there is a correspondence between SL intensity and sonochemical yield. Although often overlooked, it can be important to account for the physics and chemistry at the bubble surface.
Acoustic scattering from an elastic tube filled with bubbly fluid
Authors: Wilson Preston S. , Roy Ronald A. , Carey William M.
Published: July 2012

A complete model describing broadband sea surface scattering at high wind speeds has not been developed. One difficulty is accounting for scattering from near-surface bubble clouds. This problem has been addressed in the literature for low frequencies. To first order, an acoustically compact bubble cloud can be modeled as a compressible sphere, where the scattering strength depends only on spherical cloud volume and mean void fraction, not the bubble size distribution or cloud shape. This hypothesis has been experimentally tested using freely rising artificial bubble clouds [J. Acoust. Soc. Am. 92, 2993–2996 (1992)]. The measured low-frequency monopole target strength of the cloud agreed with theory but higher-frequency results did not. To further understand scattering from these objects, laboratory scattering experiments are underway using geometrically well-characterized bubbly fluid targets. Initial measurements of scattering from a bubbly fluid-filled latex tube are presented and compared to an effective medium theory. These initial results lack independent void fraction determination but good qualitative agreement is found, even above the monopole resonance frequency. A new method used in these experiments to generate large volumes of nearly monodisperse bubbly fluid samples will also be described. [Work supported by ONR.]
The zNose, a new electronic nose using acoustic technology
Authors: Staples Edward J.
Published: July 2012

An array of sensors simulating the human olfactory response has become known as an electronic nose, or eNose. An eNose provides a vectorial image in N-dimensional space (where N equals the number of sensors) of specific vapor mixtures containing possibly hundreds of different chemical species. Typically, eNoses have only a few sensors, produce responses that are not correlated, and have poor sensitivity. A new type of electronic nose, based upon fast chromatography and a single high-Q acoustic sensor, solves these problems by stimulating a virtual sensor array containing hundreds of orthogonal sensors. Analysis of any odor is accomplished by serially polling this virtual sensor array or a spectrum of retention times. This paper will describe the acoustic technology as well as present results for applications involving important vapors associated with several commercial foods and beverages. Part per billion sensitivity has been achieved with volatile compounds and part per trillion sensitivity for semi-volatile compounds. Because the new acoustic technology is quantitative it is the only electronic nose technology to be validated by the US EPA. The commercial expression of this technology, the zNose, is now providing an on-line quantitative measure of quality for food, beverages, cosmetics, and other aromatic products.
Recent developments in transducers: Opportunities for the future
Authors: Busch-Vishniac Ilene
Published: July 2012

Most innovations in sensors and actuators result either from the introduction of new materials, or the exploitation of newly discovered mechanisms for conversion of energy between the electrical and mechanical domains. This talk reviews new recent transducer improvements and suggests opportunities for the future of ultrasonic sensors and actuators. Although many of the transducer examples portrayed were not conceived for ultrasonic or acoustic applications, the exploitation of their materials and energy conversion mechanisms could provide a means of enhancing the arsenal of ultrasonic transducers available.
Soundscapes in American mainstream films
Authors: Flueckiger Barbara
Published: July 2012

The question of how films establish an acoustic environment was studied in the course of a research project on sound design in American mainstream film. The study was supported by the Swiss National Foundation. The corpus of this research project consisted of 96 films, their production years ranging from 1926 to 1995. Most of these films received an Academy Award for Best Sound. They were closely examined regarding their strategies to establish fictional, yet natural-seeming, soundscapes. It was discovered that the film industry developed a rather restricted vocabulary to display certain types of geographically, socially, and/or culturally defined places. The cause of the restriction can be found in technical and historical reasons as well as psychological considerations. Film soundscapes have a clear communicative function in contrary to natural soundscapes, which contain random noises. According to an unwritten Hollywood rule of the so-called classic era of the thirties and forties, any distraction from the narrative goal had to be avoided. This rule, however, was revised when multichannel formats were developed, first in the fifties with different wide-screen systems, and later in the mid-seventies with the Dolby stereo 4- to 6-channel sound system.
Sound quality of exterior vehicle noise
Authors: Genuit Klaus
Published: July 2012

For several years the acoustical engineers from all car manufacturers have been busy investigating and improving the sound quality of the interior noise of vehicles. For 20 years we have been using specific measurement technologies and analyses to describe sound quality with consideration of the signal processing of human hearing. But with respect to the exterior vehicle noise only standard measurements, e.g., the A-weighted sound pressure level, are still in use. Although the A-weighted sound pressure level has been reduced, the annoying effect of exterior vehicle noise and traffic noise has increased. The negative impact of exterior vehicle noise and traffic noise on man must be reduced. Solutions must therefore be found to the vehicle noise emission problem while allowing sustainable mobility. An important prerequisite for improvement of the well-being of the public and acceptance of future traffic and acoustic environments is the consideration of human sound perception of the exterior vehicle. This paper describes how we can transfer the knowledge of sound quality analysis with respect to interior noise to the evaluation of exterior vehicle noise. This includes not only the methodologies for the measurement and analyses, but also the development of a prediction tool.
Soundscapegraphy of old-town of Kyoto with the Gion Festival
Authors: Hiramatsu Kozo
Published: July 2012

The soundscape of the Yamahoko-cho area in the old capital of Japan, Kyoto, is described from various aspects based on an intensive survey of acoustic ecology. The area located in the city center is famous for the Gion Festival, which is one of the biggest and oldest festivals in the country. The area’s soundscape on ordinary days is basically dominated by the noises of automobiles passing through the streets, since there are also companies and shops in the area, which is the trading center of Japanese costumes, kimono. In July, when the ceremony and festival are undertaken for 1 month, the soundscape changes to be dominated by a variety of sounds related to the festival. Particularly during the days when bands of music by flutes, drums, and small gongs are performed, the soundscape of the area becomes a complete festival one. The music is so famous that it is recognized as characteristic of the city. The residents in the area are raised listening to the sounds in summer, and these sounds are closely connected with their lives. Though the music is no doubt the loudest sound heard in the area, no one complains.
Measurement of the natural soundscape in national parks
Authors: Downing J. Micah , Stusnick Eric
Published: July 2012

The National Park Service (NPS) has identified the natural soundscape in its various park units as one of the resources it has been mandated to protect. Natural soundscape is defined as the acoustic environment that would exist in the absence of human-related activity. Accordingly, the NPS has developed policies related to soundscape management, preserva-tion, and restoration, which require information about the natural ambient sound levels in all of their properties throughout the country. As part of this process, metrics and procedures for measuring the natural soundscape and assessing non-natural intrusions have been developed. Two general types of procedures have been developed: one based on audibility considerations, the other based on acoustic energy measurements. This paper describes the work that has been carried out in developing and assessing these procedures.
Noise control engineering challenges in designing power plants to meet noise limits
Authors: Putnam Robert
Published: July 2012

Noise control considerations play a vital and often pivotal role in a broad range of issues in the design of modern power plant facilities. The entire design process, from site selection, through final operational acceptance, is affected by the proper integration of the governing noise criteria, especially when relatively low levels are called for. The noise control engineer is continually challenged to justify added noise control measures, maintain adequate design margins, minimize costs, performance impacts, and design impacts, while coordinating a number of cross-discipline interfaces ranging from marketing and sales to contracts to startup and field engineering. This paper presents an overview of the principal noise control engineering tasks involved when effectively integrating required noise control features into the design process, highlights key interface requirements, and provides notes on the practicality, safety, and maintainability of control features. Illustrative examples from the author’s experience, both positive and negative, will be included.
Using a prediction model to allocate allowable noise between sources and establish equipment noise limits
Authors: Parzych David J.
Published: July 2012

Power generation facilities typically require customized noise abatement features to achieve compliance with various local and state noise regulations. Differing equipment or equipment arrangements, size and placement of equipment on the plant owner’s property, and location within a community can all affect the amount of noise control necessary for a given facility. Selecting the correct amount of silencing for each piece of plant equipment is essential when optimizing for reduced cost of the overall plant noise control treatments. To achieve the overall plant noise goals, an analytical noise prediction model of the facility is built and exercised with various equipment options until the desired goal is achieved. The paper describes methods of using a noise prediction model to allocate noise ‘‘budgets’’ among sources, and using the model to establish noise criteria in specification form. The discussion will address the overall effects of starting with poorly defined data, as well as imprecise or erroneous noise source data supplied by equipment manufacturers. Estimating reasonable and achievable noise goals for the equipment will be addressed.
Integrating noise controls into the power plant design
Authors: Bradley Wayne E.
Published: July 2012

The selection of noise controls and the specification of low-noise equipment is an important part of designing a power plant to meet specific noise limits. However, successfully interfacing with the design team and integrating these controls into the project design is an equally demanding task. The noise-control specialist must work closely with the design team to assure that the affects of the mitigation on space allocation, equipment performance, energy consumption, cooling, access to equipment, and safety are appropriately considered. Each of these factors must be addressed to assure that the controls work effectively under plant operating conditions. The design process is iterative—design details and controls may change as the design progresses. Both formal and informal lines of communication must be cultivated with the design team, and the mitigation recommendations made to them should be followed up to assure their proper incorporation into the project design. This paper describes these processes.
Noise-control engineering interacting with the design process of a power plant
Authors: Hale Marlund E.
Published: July 2012

There are many challenges which face the noise-control engineer associated with developing and implementing both the occupational and community noise controls for power generation facilities. They include becoming an early and viable part of the proposal and design process and maintaining a proper and profitable business effort. Challenges during the proposal and design phase include working within the business plan, dealing with cost estimates incorporated during the development of the winning proposal budget, the project design schedule, the engineering process, and the noise-control cost estimating and procurement process. Once a project has been won, certain financial and scheduling commitments are already in place. The project design team is then assembled and the design evolves conceptually as the various issues affecting the project are incorporated. To be a viable and effective part of the design team, the noise-control engineer must become an early player, deal with an incomplete and evolving design, keep communication lines open, stay abreast of the many facets of the design evolution, communicate project-impacting information to project management, interface with the procurement process, and stay in a position to interface with and support engineering and construction inspectors.
Customer sound criteria and vendor acoustical performance guarantees: The difficulties of meeting the first and verifying the second
Authors: Johnson Robert S.
Published: July 2012

In their procurement specifications, gas turbine end users include acoustical criteria. Gas turbine manufacturers, in accepting the criteria, specify the performance of acoustical components which are procured from acoustical component vendors for installation on the sound sources supplied by the gas turbine manufacturer. If site noise problems develop, the sound sources must be investigated and the performances of the acoustical components evaluated to determine if the performance guarantees have been met. This paper discusses one gas turbine manufacturer’s experience with how sound criteria are specified and responded to. Also discussed, are problems associated with the verification of vendor product performance guarantees, and the resolution of perceived product performance deficiencies.
Current trends in the international standardization of mechanical vibration and shock
Authors: Douglas Bruce E.
Published: July 2012

Current concerns on world trade (e.g., fair business practices, product quality, and reliability), the environment (e.g., the propagation and radiation of noise from structures), and public safety (e.g., the effects of shock and vibration on humans, civil structures, and vehicles) have placed increased international attention on the development of quality standards in the field of mechanical vibration and shock. Recognizing its importance, the International Organization for Standardization (ISO) has set up a Technical Committee to develop standards in the field of mechanical vibration, shock, and the condition monitoring of machines and structures, ISO/TC 108. Its scope includes the areas of mechanical vibration and shock pertaining to: terminology and nomenclature; actuators, sensors, and associated instrumentation; reduction and control methods; measurement and evaluation of the exposure of humans, stationary structures, vehicles, and machines. In addition, standardization in the field of vibration and shock for data processing, data acquisition, diagnostic measurement methods, transducer calibration, and condition monitoring are actively being developed. This presentation addresses topics on the broad issues of standardization in the field of mechanical vibration and shock with emphasis on (1) societal objectives, (2) economic stakes of diverse constituencies, and (3) structure, process, and future direction of ISO/TC 108.
Noise control and the machinery safety standardization program of CEN (European Standardization Committee)
Authors: Jacques Jean R. , Higginson Roger F. , Kurtz Patrick
Published: July 2012

One major aspect of the European internal market is the free circulation of products with a high level of safety. The European directive on machinery safety includes requirements to design low-noise machinery and to give out quantitative information on noise emission. One way for a manufacturer to get presumption of conformity to the directive is to use so-called harmonized European standards. In order to be harmonized and regarding noise, standards in the CEN machinery program (about 800 work items, each of them corresponding to a particular machinery family) must contain clauses on noise control and noise declaration, and a noise test code based on EN ISO 12001. Noise test codes specify the basic standards to be used for determining the emission sound pressure levels at workstations (among the EN ISO 11200 series) and the sound power level (among the EN ISO 3740 and 9614 series) and for declaring noise emission values (EN ISO 4871), together with the position of workstation(s) and the mounting and operating conditions of a machine during noise measurement. As part of a quality control system, noise consultants are employed by CEN to assess the noise contents of drafts and to assist Working Groups with noise matters.
Building acoustic ISO standards and European legal metrology
Authors: Goydke Hans
Published: July 2012

Facilitating trade in the European Union through technical harmonization of products is the purpose of the Construction Product Directive of the European Commission. An appropiate tool to be expected is the development of harmonized international standards which have to be published as national standards in every member state. The cooperation of ISO and CEN succeeded in fulfilling the task, meanwhile, in the field of building acoustics with only a few exceptions. But, before these standards are to be incorporated into the legislation in the countries, for instance regarding legal requirements on the protection against noise in buildings, it has to be verified that the application of these standards shows sufficiently corresponding results when a test object is tested in laboratories in different countries. The results of such tests available, meanwhile, are partly unsatisfying. In order to solve the problems, the development of normative additions to some of the standards, for instance in order to specify more strictly mounting conditions of test objects, are most important work items of actual building acoustics standardization.
Environmental noise: From guidelines to standards
Authors: Schwela Dietrich
Published: July 2012

In view of the new WHO guidelines for Community Noise, a concept is proposed on deriving environmental noise standards on the basis of response-exposure relationships. WHO’s guidelines have set definite guideline values for specific health effects and for specific environments. The WHO guidelines emphasize that exposure-response relationships between politically relevant variables (such as noise-induced social handicap, reduced productivity, decreased performance, absenteeism, drug use, and accidents) could definitely help decision makers to set sensible standards. In the standard-setting procedure, five different risks occur as part of any decision on the value of a standard. Three of these arise from the generalization of statements on susceptible sub-populations to be protected, on adverse effects of noise, and on boundary conditions of epidemiological studies. These risks cannot be quantified. One of the remaining two quantifiable risks is that of wrong measurements, which results from the quality of measurement techniques. The fifth risk relates to the acceptable probability of the occurrence of effects due to noise. With respect to the latter, governments have to fix an acceptable risk value in the standards-setting process. The consequences of combining these risks to a total risk are discussed.
Problems of evaluation of long-term levels for Corona noise
Authors: Wszolek Tadeusz
Published: July 2012

The ac power lines are sources of audible noise (AN), emitted as a result of Corona effect, the intensity of which depends mainly on the weather conditions. Emitted AN mostly varies between 35 and 55 dB(A) at 30-m distance. Corona AN may be considered to be composed of two major components: the low-frequency pure tones and the broadband noise. Whereas the broadband component is more or less stable, the tonal components are subject to great fluctuations. Therefore, their measurement presents certain difficulties. On the other hand, the tonal components are, according to the ISO 1996, accounted for in the AN evaluation by adding a correction to the measured level. Because of seasonal variation of the weather, long-term AN level values are taken for the evaluation, according to the ISO 1996. There is a problem concerning the evaluation of the actual periods of fair and bad weather conditions and their influence on the measurement result. The problem is also not solved by introducing the day/night levels (IEEE Std. 656). Another problem regards the environmental interference. In the paper the effect of possible errors, connected with the above-mentioned problems, on the final results of the long-term level calculations is analyzed.
Regularization of inverse problems with evanescent waves
Authors: Williams Earl G.
Published: July 2012

Due to the presence of evanescent waves, acoustic and electromagnetic radiation problems form a class of ill-posed inverse problems when the vibration (electric currents) is to be determined solely from a near-field measurement of the pressure (electric field), as is done in near-field acoustical holography. The problem is ill posed since small changes in the measured pressure lead to large changes in the reconstructed velocity. Regularization of the problem is crucial. We will discuss various regularization methods which have been tested against experimental data and show how they can be modified and tuned in an effort to incorporate the physics of the decaying fields into them. In this way, we hope to identify a single technique which provides near optimum inversion of the ill-posed problem. [Work supported by ONR.]
Reconstruction of acoustic radiation from an arbitrarily shaped object using the CHELS method
Authors: Wu Sean F. , Zhao Xiang
Published: July 2012

The combined Helmholtz equation–least-squares (CHELS) method developed previously by the authors [J. Acoust. Soc. Am. 107, 2799 (2000)] is used to reconstruct the acoustic field radiated from an arbitrarily shaped object. The main advantage of the HELS method [Wang and Wu, J. Acoust. Soc. Am. 102, 2020–2032 (1997); Wu, ibid. 107, 2511–2522 (2000)] is its simplicity in expressing the radiated acoustic pressure in terms of an expansion of certain basis functions, whose coefficients are determined by matching the assumed-form solution to the measured acoustic pressures. The number of expansion functions determines that of the measurements, which is small for structures that can be described by spheroidal coordinates. Combining the HELS method with the Helmholtz integral formulation will further allow for reconstruction of acoustic radiation from an arbitrarily shaped structure. This CHELS method is applied to a four-cylinder engine block. The normal component of surface velocity is reconstructed using singular value decomposition and a regularization technique. The corresponding surface acoustic pressure is obtained by solving the Helmholtz integral equation. Once these surface quantities are specified, the normal component of time-averaged acoustic intensity can be determined. Results of this study demonstrate that the CHELS method can become potentially a powerful noise and vibration diagnostic tool for practicing engineers. [Work supported by NSF.]
A cross-linguistic acoustic study of fricatives
Authors: Gordon Matthew K. , Barthmaier Paul , Sands Kathy
Published: July 2012

This work presents results of an acoustic study of fricatives in 7 languages (Aleut, Chickasaw, Hupa, Montana Salish, Scottish Gaelic, Toda, and Western Apache), all of which contrast fricatives made at several places of articulation. Measurements of the frequency of spectral peaks and centroid frequencies indicate many similarities between the languages in the acoustic properties defining the fricatives. Some of the principal findings are the following. Alveolar sibilants typically have the highest spectral peak and centroid frequency. Lateral and palatoalveolar fricatives have spectral peaks and centroids intermediate in frequency between alveolar sibilants and backer fricatives. Among the back fricatives, peaks and centroids of uvulars are characteristically lower than those of velars. Rounding of back fricatives induces further lowering of peaks and/or centroids. Contrasts in backness and rounding among the back fricatives are also associated with differences in F2 of the following vowels: F2 values are lower following uvulars than velars, and lower following rounded than unrounded fricatives. Labiodental fricatives typically have flat spectra with poorly defined spectral peaks. Finally, the contrast between lateral fricatives and palatoalveolar sibilants is variably realized, depending on language and speaker, as a difference in the location of spectral peaks and/or centroid frequency.
Cues for place and palatalization in Russian stops
Authors: Richey Colleen
Published: July 2012

Using acoustic measurements and native speaker perceptions, the cues for place of articulation of Russian plain and palatalized stops were investigated. The acoustic measurements were made of formant transitions, burst duration, and spectral burst shape. They showed that formant transitions distinguish place of articulation of plain consonants, but not palatalized consonants. Differences distinguishing place of articulation were found in the burst durations and in the ratio of energy between the upper and lower portions of the burst spectra. In the perception experiment, native Russian speakers listened to various consonant–vowel stimuli. Hearing only the formant transitions, listeners were able to identify place of articulation of just the plain stops. When they heard stimuli with conflicting cues for place in the burst and formant transitions, in the majority of the cases, they identified plain consonants based on the formant transitions, but they identified palatalized consonants based on the burst. It is concluded that while formant transitions do provide the strongest cues for place among plain stops, they do not provide cues for place among palatalized stops. The cues for place of articulation of palatalized consonants are contained completely in the duration and spectral shape of the burst.
An evaluation of phonetic working space in normal geriatrics and persons with motor speech disorders
Authors: Bunton Kate , Westbury John , Weismer Gary
Published: July 2012

Speakers with dysarthria seem to have smaller than normal phonetic working spaces. Their vowels exhibit unusual and often reduced formant transitions and slopes, and areas enclosed by their ‘‘vowel locations’’ plotted in an (F1,F2) plane are abnormally small. Presumably, reduced formant transitions reflect small movements of individual articulators. Reduced lip and jaw movements have been reported for speakers with Parkinson’s disease and amyotrophic lateral sclerosis. However, comparable reports for tongue movement are not available. In this study, x-ray microbeam data were used to compare the acoustic and articulatory phonetic working spaces of neurologically normal and dysarthric speakers. Measurements of formant frequencies, and sagittal-plane locations of tongue fleshpoints, were made for the English vowels /i ae a u/ at the temporal midpoint of the vowel nucleus in three different words for each of ten normal and seven dysarthric speakers. Speakers’ articulatory phonetic working spaces were defined as areas enclosed by tongue fleshpoint locations. Data obtained from this study provide an enhanced appreciation of the articulatory bases of acoustic features of dysarthric speech. [Work supported by 1-R01-DC03723.]
Observing the link between speech production and speech perception from disordered speech
Authors: Wang Emily Q. , Xu Yi , Kompoliti Katie , Goetz Christopher G.
Published: July 2012

It was recently reported that individuals with idiopathic Parkinsons Disease (PD) and hypokinetic dysarthria were able to signal sentence focus using acoustic parameters such as f0, intensity, and vowel duration that normal speakers use. However, it was also found that PD speakers did not show all the f0 patterns that normal speakers use. For example, although the f0 range of the word under focus was expanded, the f0 range of the postfocus word was not always suppressed. In this paper, the f0 patterns produced by ten speakers with idiopathic PD (Hoehn and Yahr stage 3 and 4, off) and mild, or mild-moderate, or moderate hypokinetic dysarthrias will be examined. These patterns will also be correlated to their perception by normal speakers. The following issues will be addressed: (1) Can listeners correctly perceive focus produced by the PD speakers when the f0 patterns are similar to those used by normal speakers? (2) Can listeners correctly perceive focus when there are missing cues in the f0 patterns (e.g., lack of post-focus suppression)? (3) Can misperception result from the speakers attempt to compensate for their articulatory limitations due to the disease process? Implications of the findings will be discussed in terms of speech motor control.
Vocal-tract model experiment for illustrating vowel production
Authors: Hong Soo-Ki , Yoon S. W.
Published: July 2012

Everyone can articulate the same words even though each individual has unique vocal organ. Findings of common features in the same vowels articulated by everyone are very useful for speech recognition and reproduction. In this study a vocal tract is modeled with a cylindrical silicone tube to understand the mechanisms of vowel production. The constrictions on the tube are varied with locations, lengths, and degrees. The resonance frequency shifts of vocal-tract depend on the length ratio and the cross-section area ratio of the constriction in the tube. The resonance frequencies show good correlation with the formants measured in speech. [One of the authors (SWY) was supported by the BK21 project.]
Simulations of voice onset–offset hysteresis in /aha/ utterances
Authors: Lucero Jorge C. , Koenig Laura L.
Published: July 2012

The subcritical Hopf bifurcation model for voice onset–offset hysteresis [J. C. Lucero, J. Acoust. Soc. Am. 105, 423–431 (1999)] is investigated considering the glottal area as control parameter. A two-mass model of the vocal folds coupled to a two-tube approximation for the vocal tract is used for producing oral airflow simulations. The glottal rest area is varied in an abduction–adduction pattern to reproduce smoothed oral airflow records measured during /aha/ production [L. L. Koenig and R. S. McGowan, J. Acoust. Soc. Am. 100, 2689(A) (1996)]. The resultant simulations show good agreement with the unsmoothed measured records, with a clear hysteresis effect: vocal-fold oscillation stops during glottal abduction at a higher value of the glottal area than the value at which it starts during the adduction. The dependence of the onset–offset hysteresis and voice parameters on vocal-fold stiffness (Q factor), subglottal pressure, and male–female laryngeal configurations is analyzed and illustrated with bifurcation diagrams. [Work supported by CNPq, Brazil, and NIH.]
Acoustic penetration at subcritical grazing angles: Measurements and comparison with simulations based on perturbation theory
Authors: Jackson Darrell R. , Williams Kevin L. , Tang Dajun , Thorsos Eric I.
Published: July 2012

As part of the SAX99 experiment, a buried hydrophone array was deployed together with a movable tower with attached sources covering the frequency range 11–50 kHz. This system was used to examine subcritical penetration into the sediment. For incident grazing angles below the critical angle, scattering dominates the penetrating field. Comparisons with simulations based on perturbation theory show that the penetration is predominately the result of diffraction by the low-amplitude ripple field prevalent at the SAX99 site. Simulations predict a cutoff effect as a function of frequency and grazing angle that is found in the data, and predict changes in penetration as a function of ripple field amplitude that are consistent with those observed. [Work supported by ONR.]
Acoustic wave propagation in granular media
Authors: Kimura Masao , Chotiros Nicholas P.
Published: July 2012

The frame bulk and shear moduli are important in analyzing the acoustic wave propagation in marine sediments. The frame bulk and shear moduli of marine sediment are related to the longitudinal and shear wave velocities in dry marine sediments. The measured results of the longitudinal wave velocities in dry glass beads with four different grain sizes, but with almost the same porosity have been reported. The measured results showed that the longitudinal wave velocity largely increases, as the grain size increases. This result could not be explained using the classical contact theory, such as the Hertz–Mindlin or Digby model. In this study, we use the longitudinal wave velocities of dry glass beads in air and in vacuum to investigate the effects of the air, as the pore fluid. The measured results show that the longitudinal wave velocities in vacuum are smaller than that in air, and the velocities in vacuum become almost constant, even though the grain sizes are different.
Biological and hydrodynamic control of seafloor roughness: Implications to high-frequency acoustic scattering
Authors: Richardson Michael D. , Briggs Kevin B. , Williams Kevin L.
Published: July 2012

Biological and hydrodynamic processes can both create and destroy seafloor microtopography. As part of the SAX99 experiments, natural and artificial temporal changes in seafloor roughness were monitored acoustically and quantified using bottom stereo photographs. Feeding activities of benthic megafauna and fish destroyed large-scale roughness features generated by ocean surface gravity waves within a period of weeks to months; whereas, fine-scale roughness created by raking the seafloor decayed to background levels within 24 h. The effects of fine-scale roughness increased acoustic scattering centered at one-half the acoustic wavelength (a Bragg wavelength of 2 cm) by 12–18 dB in artificial manipulations of the bottom. These changes were restricted to roughness that was oriented predominantly orthogonal to the incident acoustic waves. Alternatively, seafloor roughness generated by ocean surface gravity waves had wavelengths of 50–100 cm and wave heights of 10–15 cm. These predictable large-scale roughness features should, by analogy, dramatically increase scattering at lower acoustic frequencies (near 1–2 kHz) and decay within weeks to months after storm events. [Work supported by ONR.]
Acoustic properties of a triple-leaf membrane
Authors: Sakagami Kimihiro , Morimoto Masayuki , Kiyama Masakazu
Published: July 2012

Acoustic properties of a triple-leaf membrane, consisting of two impermeable and one permeable leaves, are theoretically analyzed under a simple condition in which a plane wave is incident normally. The triple-leaf membrane shows different acoustic properties according to where the permeable leaf is placed. When the permeable leaf is placed in the cavity between two impermeable leaves, its absorptivity shows two mass–air–mass resonance peaks, one by the first and second leaves, and the other by the first and third leaves, provided that the permeable leaf is of sufficient flow resistance and mass. These peaks can be merged to produce one larger peak so that the structure can offer higher absorptivity over a wider frequency range, when the masses of leaves and the cavity depths are adequately adjusted. A parametric study shows that the sound absorption and insulation performances of a triple-leaf membrane of this type are better than those of a double leaf with an air cavity only, though a double leaf with an absorbent in its cavity is still the most efficient. A method to optimize the system parameters to obtain maximum absorptivity is also suggested. Another arrangement, with the permeable leaf as the first leaf, is also explored.
Ultrasonic eyeglasses for the blind
Authors: Kay Leslie
Published: July 2012

There is an obvious need for blind persons to perceive their environment in the greatest detail possible. The bat has demonstrated the effective use of ultrasonic waves for its own purpose of perceiving its environment. Man now has his own air-sonar technology, in the form of eyeglasses mounted on the head, so as to perceive his environment. It may well be the best that can be achieved for helping blind persons by using their auditory channels to the cortex for spatial imaging and cognition of object space. This address describes the octave band CTFM air sonar with auditory coupling to the brain. The method of testing its physical performance is related to the human auditory perception of object space experienced by users. FFT analysis shows a distal resolution of approximately two wavelengths. However, behavioral analysis of a user performance suggests a greater neural ‘‘resolution’’ of object space is available. This resolution is demonstrated by the natural real-time perception of object-shape characteristics. The ‘‘infinity’’ of sonar object ‘‘signatures’’ are seemingly absorbed by the listener’s neural system and eventually learned. The small nuances in the real-time change in sound structure as an object pose is altered are invariant. This requires an enormous memory.
Assessing ocean noise: A conservationist approach
Authors: Reynolds Joel R. , Jasny Michael D.
Published: July 2012

The regulation of ocean noise is an evolving process that involves representatives of the environmental community as well as scientists and regulators. This paper describes a three-stage procedure, based on the precautionary principle, that is currently being used by environmentalists to identify acoustic projects with potentially significant biological impacts: (1) a threshold stage of review, in which factors such as the ecological significance of the operation area, the intensity, frequency, and duration of the source, the mitigation offered by project applicants, and the cumulative and precedential impacts of the project are considered; (2) a period of consultation with experts in the field; and (3) an assessment of the project according to the substantive, procedural, and evidentiary standards set forth by applicable statutes and regulations, including the National Environmental Policy Act, Marine Mammal Protection Act, and Endangered Species Act. In the third stage, projects are evaluated according to the integrity of their alternatives analysis, especially with regard to location and season; the consistency of their environmental assessment with the best available science; the significance of their reasonably anticipated cumulative impacts; their objectivity in identifying data gaps; and their commitment through mitigation to have the least practicable impact on the marine environment.
Optical Mie scattering to observe single cavitation bubble dynamics
Authors: Holt R. Glynn
Published: July 2012

It is often advantageous to know precisely the instantaneous response of bubbles to an external acoustic field. One technique to enable such observations consists of detecting the time-resolved optical scattering of an incident laser beam from a bubble. For visible laser light and bubble radii on the order of 1–100 microns, reflection, refraction, internal interference, and diffraction must all be taken into account, and the scattering so described is named after Gustav Mie. Physical principles and the mathematical development will be discussed. Several specific applications will be presented and the results discussed. Finally, a brief list of ‘‘do’s and don’ts’’ for the potential user will be discussed.
Characterization of ultrasound contrast agent oscillations
Authors: Ferrara Katherine , Morgan Karen , Chomas James , Allen John
Published: July 2012

Ultrasound contrast agents consist of a gas bubble surrounded by a shell, and are used in studies of tissue perfusion. It is currently difficult to differentiate contrast agent echoes from nonlinear components of tissue echoes. A goal of this research is to improve the understanding of individual contrast agent oscillations and the resulting received echoes. This, in turn, can lead to more sophisticated bubble detection techniques by designing pulsing schemes to elicit a specific bubble response. In this study, experimental and theoretical tools are uniquely combined to aid in the understanding of a bubble’s response during insonation. A model is used for comparison, which is based on the equation developed by Rayleigh for an unencapsulated bubble, with additional terms to include the effects of shell elasticity and viscosity. The resulting radius-time curves are validated by direct comparison with the experimental results from a high-speed optical system capable of 100 million frames/s. One resulting signal processing strategy involves the transmission of a train of wide-band pulses with alternating phase which yields echoes with significant spectral differences, quantified by calculating the mean frequency of each echo. A new bubble detection technique is proposed based on these differences in mean frequency.
Effect of dual-reflector lithotripter on stone fragmentation and cell damage
Authors: Sokolov Dahlia L. , Bailey Michael R. , Crum Lawrence A.
Published: July 2012

An electrohydraulic lithotripter uses an ellipsoidal reflector to focus shock waves on to a kidney stone. The shock wave generates a cylindrical cavitation field, ∼1 cm wide×10 cm long, that has been implicated in both stone fragmentation and damage to healthy tissue during lithotripsy treatment. A dual-reflector lithotripter, consisting of two identical spark-gap lithotripters facing each other and firing simultaneously, creates a more localized cavitation field, ∼3 cm wide×5 cm long (Sokolov, Berlin 1999). Such a field may increase the rate of stone fragmentation while mitigating damage to surrounding tissue. Breakage of model stones at the focus and hemolysis of red blood cells 3 cm from the focus were assessed for both conventional lithotripsy (CL) and dual-reflector lithotripsy (DRL). To equalize total energy input, the number of shots was halved from CL to DRL. Stones subjected to DRL were broken into several major fragments while stones subjected to CL remained intact except for some dust. Human blood was diluted to 3% hematocrit in degassed PBS and placed in acoustically transparent sample tubes. There was no statistical difference in percent hemolysis between CL (5.12±1.01%) and DRL (5.39±0.57%). [Work supported by NIH DK43881 and NSF.]
Cavitation enhanced acoustic hyperthermia
Authors: Edson Patrick , Holt R. Glynn , Roy Ronald A.
Published: July 2012

The dominant mechanisms through which cavitation activity may lead to enhanced heating in tissue and tissue-like media with high-intensity focused ultrasound remain unclear. Previously, the authors have reported the results of experimental [J. Acoust. Soc. Am. 104 (A) (1998)] and numerical [ibid. 106 (A) (1999)] investigations which sought to understand the relationship between parameters relevant to the cavitation field, dominant heating mechanisms, and the magnitude of the enhanced heating effect. The model has since been extended to better account for heating from acoustic re-radiation. Results of expanded numerical simulations which incorporate bubble related heating source terms in an existing FDTD code designed to calculate temperature response as a function of the incident acoustic field are reported. Experiments aimed at manipulating the cavitation field to facilitate reproducibility and control are also reported. [Work supported by DARPA.]
The ‘‘underwater’’ sounds from the impact of drops in superfluid 4He
Authors: Apostolou Antonios , So Jin H. , Lu Zhiqu , Gladden J. , Bradley Eliza S. , Maynard J. D.
Published: July 2012

When a drop of a liquid impacts onto a liquid surface a crater is formed, and the cavity dynamics that follow determine whether or not a bubble will be entrained. The entrainment of an air bubble following the impact of a raindrop onto the sea provides the predominant mechanism for the production of the underwater noise from rain. Experiments in water have indicated one particular entrainment region in a dimensionless parameter-space. This talk describes an ongoing research effort to study the phenomenon on a more fundamental basis using, instead of water, the pure and highly characterized liquid helium. The impact of liquid helium drops on a liquid helium surface is monitored by employing acoustic and optical techniques. Bubble entrainment in superfluid 4He, as well as the transition to nonentrainment, are observed, and the collected data indicate a new entrainment region. In addition, high-speed images of the crater motion reveal novel crater dynamics for the nonentrainment case. [Research supported by National Science Foundation DMR 9801844 and the Office of Naval Research.]
Effects of nonuniform stress on the properties of lead zirconate titanate
Authors: Janus Robert S. , Powers James M. , Tito Frank A. , Moffett Mark B. , Jevnager Michael D.
Published: July 2012

The variations in the piezoelectric constant, d33, and the dielectric constant, K33T, for Navy type III lead zirconate titanate piezoelectric ceramic under nonuniform compressive mechanical stress have been experimentally evaluated. Peak compressive stress levels as high as 290 MPa (42 kpsi) with electric field intensities up to ±790 kVrms/m (±20 Vrms/mil) were applied to a stack of piezoelectric ceramic bars. The maximum d33 and stress-averaged K33T values measured were 159% and 135% larger, respectively, than the corresponding catalog values specified at low field and without a mechanical bias. The electrical losses of the material measured under the above conditions are also reported. [Work supported by the Space and Naval Warfare Systems Command.]