bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of ultrasound-mediated reversible membrane permeabilization for targeted drug delivery
Authors: Prausnitz Mark R. , Keyhani Keyvan , Parsons Aimee , Lewis Thomas N.
Published: July 2002

Ultrasound-mediated permeabilization of cell membranes is a potentially useful method to noninvasively enhance delivery of therapeutic compounds into targeted cells. Unlike previous studies concerned only with cell death, in this study the effects of ultrasound exposure parameters on reversible membrane permeabilization of prostate cancer cells were determined. Cells were suspended in a solution containing a membrane-impermeant marker (calcein) and exposed to 24-kHz ultrasound. Viability and molecular uptake were quantified using flow cytometry. Average uptake increased with incident ultrasound pressure above a threshold and reached a plateau (20%–25% of external calcein concentration); increased with total exposure time; was weakly dependent on pulse length (3.3 ms to 1.0 s) with a small maximum at 10–33 ms and a sharp decline at 1.0 ms; and was independent of duty cycle (0.5%–50%). The fraction of viable cells decreased continuously with increasing pressure, decreased as uptake increased for most other examined condition was approximately 25% for maximum uptake under optimal conditions. Uptake decreased approximately exponentially with the time at which calcein was added to the cell suspension after exposure, with a time constant of about 1 min. The membrane disruptions allows uptake of albumin (MW=66 000) but not R-phycoerythrin (MW=240 000).
Optimization of the piezoelectric circular bimorph
Authors: Dobrucki Andrzej
Published: July 2002

The combined finite-element and boundary-integral method was applied for modeling of vibration and sound radiation of piezoelectric circular bimorphs. The bimorph consists of two circular piezoelectric disks, which are separated by a metal plate. When an electric voltage is supplied to the bimorph, a bending moment develops which actuates the transducer to transversal deflection. During the design process of the transducer the following limitations must be taken into account: (1) piezoelectric material and thickness of the disks are usually predetermined, (2) the outer diameter of the transducer, i.e., of the metal plate is given. The influence of the metal plate material and its thickness on the frequency response of the transducer is discussed. Young’s modulus, Poisson’s ratio, density, and the loss factor characterize the properties of the materials. The influence of the ratio of a piezoelectric disk’s diameter to metal plate diameter is also discussed. Another important property which was considered during the optimization process, is the mounting of the transducer, i.e., applied boundary conditions. As an example, the design of a small transducer is presented. The results of calculations are in good accordance with the result of the measurement of realized construction.
Hydrodynamical perturbation effects in multiple-bubble sonoluminescence
Authors: Robinson Alex , Kuhns David W. , Brodsky Anatol M. , Burgess Lloyd W.
Published: July 2002

This presentation will describe the observation of new dynamical effects in multibubble sonoluminescence (MBSL). The experiments show a specific time-dependent nonmonotonic response of MBSL in aqueous and organic solutions to hydrodynamical perturbations caused by sudden pressure changes. Through a fast pressure jump, the bubble field is forced into an excited metastable state, subsequently relaxing over a period of seconds to minutes. The period and intensity of the system excitation is highly dependent upon physical parameters and small concentrations of surface active species. By monitoring the system via sonoluminescence intensity, low level quantitation of alcohols and earth metals in water as well as percent concentrations of water in alcohols has been performed. [Work supported by the Center for Process Analytical Chemistry.]
Pseudo-Rayleigh and pseudo-Scholte surface acoustic solitons
Authors: Gusev Vitalyi , Glorieux Christ , Thoen Jan
Published: July 2002

Soliton solutions for the equation s2(∂v/∂x)=α(∂/∂τ)v2+β(∂/∂τ)(H[v])2−D(∂2/∂τ2)H[v], describing wave propagation on a fluid–solid interface covered by elastically linear film, have been found analytically. In this equation x is a ‘‘slow’’ spatial coordinate, τ is a ‘‘fast’’ time, α and β are nondimensional nonlinear parameters, S is the wave velocity in the absence of a film, and H denotes the Hilbert transform with respect to τ. This equation generalizes the recently proposed model for nonlinear Rayleigh waves [J. K. Hunter, Contemporary Math. 100, 185–202 (1989)] and the equation derived for Scholte waves [Gusev et al., IEEE UFFC (1998)], where D=0, by accounting for linear variation of the wave velocity with frequency D≡∂sp/∂ω(ω=0+0). Velocity dispersion sp=sp(ω) [s≡sp(0)] is due to interface loading by an acoustically thin film and described by the last term in the right-hand side of the equation. The problem of the nonlinear surface/interface wave amplitude distribution in the interior of the medium is also addressed.
Vector fields and quadratic maps
Authors: Davies Huw G. , Karagiosis Konstantinos
Published: July 2002

Vector fields describing responses of nonlinear systems are often investigated by sampling on a suitable Poincaré section. For example, period-1 limit cycles yield one fixed point, period-2 two points, and so on. More information could be obtained if the full return map on the section rather than just the fixed points were known. Such a map can be obtained numerically from transient analysis of the system. Instead, an analytic approximation of the map is discussed here, in the general quadratic form xi(t)=aij(t)xj(0)+bijk(t)xj(0 )xk(0) . xi(t) are perturbations away from the limit cycle, t=0 being chosen on the Poincaré section. This equation with t=T, the fundamental period, is the required map. aij(T) is the Floquet monodromy matrix. Differential equations for aij and bijk are obtained from a Taylor expansion of the system equations and solved recursively. The three-dimensional Rössler attractor which is known to yield a smooth, one-dimensional unimodal map is used as an example. [Work supported by NSERC.]
Tomographic scanning acoustic microscope system
Authors: Ko Daesik , Song Daekun , Jun Kyesuk
Published: July 2002

In this paper, a new type of acoustic microscope system using the tomographic image processing technique of STAM (scanning tomographic acoustic microscope) and operation principles of the transmission-mode and detection technique of SAM (scanning acoustic microscope system) is proposed. Since SAM and scanning laser acoustic microscope system (SLAM) used in the past were operated at the reflection mode, these systems could not obtain high-resolution tomographic images. Although STAM could process tomographic images, due to the detection-using laser, problems such as complex detection hardware, alignment, and low S/N ratio occur. If the tomographic image processing technique is used for ultrasonic microscope systems, the axial resolution can be enhanced and it can help and work together with the existing systems to detect cracks that are difficult to find in the reflection mode. These experimental results will be used for various ultrasonic microscope tomographic image processing and ultrasonic measurements.
Motion compensated high-frequency synthetic aperture sonar
Authors: Christoff James T.
Published: July 2002

The Coastal Systems Station has recently completed a set of sea tests using a high-frequency synthetic aperture sonar (HFSAS) mounted on a towed underwater vehicle. The processed results from these tests demonstrate that 2.5-cm resolution can be achieved in shallow water from a small physical array. This system had a Doppler unit to control the ping rate, but had no inertial navigation system and depended entirely upon acoustic backscatter from the seabed to correct for vehicle deviations in the line of sight. In these sea tests the dual overlapped phase center technique [Sheriff, Symposium on Autonomous Underwater Vehicle Technology, pp. 236–245, 1992] was used as the motion compensation algorithm. The tests were conducted over a target field in the Gulf of Mexico that contained a variety of targets, both small sphere and minelike targets. This paper will present results from the HFSAS in the form of a point response function and an acoustic image. The HFSAS achieved between 2.5- and 3-cm resolution on the smallest sphere and produced excellent images of the remaining targets out to a range of approximately 70 m. [Work supported by ONR.]
Japan’s new National Performing Arts Center
Authors: Yanagisawa Takahiko
Published: July 2002

Japan’s first National Performing Arts Center, a ‘‘theater city,’’ was opened in the Shinjuku district of Tokyo in the fall of 1997. The center is composed of the New National Theatre, which was the winning design in an international architectural competition in 1986, and Tokyo Opera City and covers a total area of 11 acres. The New National Theatre includes an opera house, a drama theater, and an experimental theater, while Tokyo Opera City comprises a concert hall, a skyscraper, and shops. The center promises to become the focal point of theatrical and musical activity in Japan. The architectural goal was to create spaces which would fully engage the human senses, becoming a ‘‘sanctuary of memorable experiences.’’ Special focus was placed on the enhancement of the live sound produced by the human voice as well as instrumental sound. The acoustical consultant and associated laboratory were intimately involved from the beginning, and it was therefore possible to integrate their ideas into the design at an early stage. The team also conducted measurements of many of the world’s finest halls. Each of the halls boasts its own distinct character, and they are acclaimed by musicians, audiences, and critics alike.
Time pattern of Sperm whale codas recorded in the Mediterranean Sea 1985–1996
Authors: Pavan G. , Hayward T. , Borsani J. F. , Priano M. , Manghi M. , Fossati C.
Published: July 2002

Sperm whales, Physeter macrocephalus(catodon), emit short click sequences, called codas, with regular time patterns [Watkins and Schevill, J. Acoust. Soc. Am. 62, 1485 (1977)]. Since codas recorded in different geographical areas have different and stable patterns, they possibly serve to convey regional information. More than 120 codas were recorded in the Central Mediterranean Sea in the years 1985–1996 by several research groups using a number of different detection instruments, including stationary and towed hydrophones, military sonobuoys and passive sonars. All of the recorded codas share the same time pattern 3+1 (///-/) with an overall duration ranging from 456 to 1280 ms and an average value of 910 ms. Even if the coda duration varies, the click pattern remains significantly stable. In the present work, the repetition rate and time pattern of Mediterranean codas are characterized, also taking into consideration their possible biological and geographical role. [Work supported by the Italian Ministry of the Environment, Inspectorate for Sea Protection, and by the Italian Navy. Work of the second author supported by ONR Base funding at NRL.]
Active noise control of a single-engine light aircraft cabin
Authors: Kestell Colin D. , Hansen Colin H.
Published: July 2002

Active noise control (ANC) shows success and potential in a growing number of commercial applications, one of which is aircraft cabin noise reduction. With the exception of utilizing ANC headsets, light aircraft, which to date offer a high noise environment, have been somewhat overlooked. The importance of weight minimization also prevents installing copious quantities of dampening and insulation materials as a passive noise control measure. While headsets are a pilot’s necessity and an obvious target for ‘‘localized’’ noise reduction, they are not conducive to either operator or passenger comfort. High noise levels not only render communication difficult but also contribute toward stress and fatigue. A more globalized region of reduced noise will be less restrictive and no doubt provide the occupants with more freedom of movement and overall comfort. Light aircraft operators boasting quieter cabins with a focus on customer comfort will no doubt have a distinct commercial advantage. Using flight trials and laboratory experiments as a basis, this paper will discuss the introduction of ANC into a four-seater Piper Archer. Existing noise levels, objectives, equipment used, methods of approach, and results to date shall be reviewed, as well as the remaining work required to achieve the final goal.
Anticipated effectiveness of active noise control in propeller aircraft interiors as determined by sound quality tests
Authors: Powell Clemans A. , Sullivan Brenda M.
Published: July 2002

Active noise control technology offers the potential for weight-efficient aircraft interior noise reduction, particularly for propeller airplanes. However, there is little information on how passengers respond to this type of interior noise treatment. This paper presents results of two experiments which use sound quality engineering practices to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller airplanes. Binaural recordings were made in five different propeller airplanes and a commercial jet using an acoustic mannequin and a digital recording system. The noise stimuli for the tests were prepared by digitally modifying the propeller tones in recordings of each airplane type to simulate active noise control systems with a range of effectiveness and complexity. The noise stimuli were presented to the test subjects through electrostatic headphones to preserve the realism, spatiality, and directionality provided by the binaural system. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Changes in subjective response relative to changes in measured sound characteristics afforded by the hypothetical active noise control schemes are presented and are contrasted between the two test methods.
Range-dependent matched-field source localization and tracking in shallow water on a continental slope
Authors: Taillefer Martin L. , Chapman N. Ross
Published: July 2002

This paper describes matched-field source localization and tracking of a sound source towed over a continental slope off the western coast of Vancouver Island. The data were collected using a multielement vertical line array (MEVA) as part of the PACIFIC SHELF sea trial carried out during September 1993. The MEVA is a 16-element array with sensors evenly spaced at depths between 90 and 315 m. The target was towed along a linear radial track over a steep slope out to ranges of 5.5–6 km from the array, and then along a navigational arc in water depths from 250 m at the array to 750 m. The target emitted three continuous wave tones in the band 45–72 Hz. In order to model the environment as accurately as possible, the replica fields were calculated using an adiabatic normal-mode approximation which accounted for elastic wave propagation in the bottom. In addition, a bathymetric database was compiled from various echo-soundings of the area. Using conventional linear MFP based on two-dimensional replica fields to determine ambiguity surfaces for any target radial from the array, the target was tracked in range, depth, and bearing along the entire experimental track, with Bartlett processor values as large as 0.87.
The search for cavitation in vivo
Authors: Carstensen Edwin L. , Gracewski Sheryl , Dalecki Diane
Published: July 2002

Until the mid-1970s, it was generally assumed that with the short pulses of ultrasound used in medical diagnosis, there was little need for concern about the possibility of inertial cavitation in vivo. Conversations with Hugh Flynn at about that time made it clear that complacency in this respect was not warranted. Flynn carried out a comprehensive theoretical study of the response of microbubbles to diagnostically representative pulse exposures culminating in a publication, which is now the classic basis for an understanding of cavitation in diagnostic medicine. Robert Apfel independently published similar conclusions at about the same time. Flynn’s contributions continued in a collaboration with Charles Church. Experimental evidence that cavitation in vivo might be relevant to the use of diagnostic ultrasound began with observations of the killing of fruit fly larvae with microsecond length pulses. Later, the mammalian lung was shown to be particularly vulnerable to these exposures. Noting that purely positive pulses were as damaging as purely negative pulses, Ding and Gracewski showed that inertial cavitation is greatly inhibited by bubble constraints that might occur in tissue. Most recently, hemolysis and hemorrhage associated with the use of contrast agents have provided nearly incontrovertible evidence of the occurrence of cavitation in vivo.
A new time-domain approach for nonlinear wave propagation: Comparison with the KZK equation approach in the case of an unfocused cw beam
Authors: Tavakkoli Jahangir , Sapozhnikov Oleg A. , Souchon Remi , Cathignol Dominique
Published: July 2002

A time-domain numerical model for simulating acoustic pulse focusing in soft tissue has already been presented. In this model, the main effects responsible for finite-amplitude wave propagation, i.e., diffraction, frequency-dependent attenuation, and nonlinearity, were taken into account. Here, a comparison between the results of this model with those of the KZK model is presented. Using this model, the acoustic pressure field of a plane circular transducer was simulated in water for a large range of cw-mode input excitation levels. The on- and off-axis pressure-time waveforms and their corresponding harmonic components were calculated using this model and the KZK model, and very good agreement was obtained between the two models. Furthermore, these results were verified by previously published experimental measurements. At present, all implementations of the KZK model are limited to planar or weakly focused sources. This study, along with this group’s previous work, reveals the validity of this finite-amplitude wave propagation model for a wide degree of source focusing (from a planar to a highly focused source), and in cw as well as PW modes. It is also shown that the computation time for this model is much less than for the KZK, using the same input parameters.
Diffraction and conversion of the A wave on a T structure
Authors: Morvan Bruno , Tinel Alain , Duclos Jean
Published: July 2002

The A wave propagates without attenuation in an immersed plane plate. So it can be potentially used in nondestructive inspection for great dimension structure. The A wave propagation is well understood in canonical structures (cylindrical shell, infinite plate). In this paper, a T structure is studied: a brazed perpendicular plate positioned on another one. This stucture is identified as an attached substructure like stiffeners, bulkheads, rib, etc. The experimental study has been performed with a sample made of different metals (stainless steel, brass) and with plates of different thicknesses (frequency-thickness product ∼0.5 to 1.5 MHz mm). The A wave is generated at the end of the plate by the conversion of a pulse bulk wave. A second immersed transducer collects the A-wave diffracted signal, at the plate’s junction, at a given observation angle. It should be noted that the A wave is reflected and transmitted; it is also converted into a Lamb wave on the principal plate and the perpendicular plate. The spectral analysis of received signal, for different angles, allows the reconstitution of the Lamb wave dispersion curves.
The use of visible speech cues (speechreading) for directing auditory attention: Reducing temporal and spectral uncertainty in auditory detection of spoken sentences
Authors: Grant Ken W. , Seitz Philip F.
Published: July 2002

It is well established that auditory-visual speech recognition is far superior to auditory-only speech recognition. Classic accounts of the benefits of speechreading to speech recognition treat auditory and visual channels as independent sources of information that are integrated early in the speech perception process, most likely at a precategorical stage. The question addressed in this study was whether visible movements of the speech articulators could be used to improve the detection of speech in noise, thus demonstrating an influence of speechreading on the processing of low-level auditory cues. Subjects were required to detect the presence of spoken sentences in noise under three conditions: auditory-only, auditory-visual with a visually matched sentence, and auditory-visual with a visually unmatched sentence. The potential benefits of congruent visual speech cues to auditory detection will be discussed in terms of a reduction of signal uncertainty, in both temporal and spectral domains. In effect, the visual channel may serve to inform the auditory system about when (in time) and where (in frequency) to expect changes in the acoustic signal. [Work supported by NIH Grant DC00792.]
The role of memory in the dual-task: Evidence from a frequency/amplitude judgment
Authors: Gallun Erick , Bonnel Anne-Marie , Hafter Ervin R.
Published: July 2002

Subjects judged changes in the amplitude and/or frequency of a 100-ms signal either within a trial (experiment one) or between trials (experiment two). Within-trial changes featured roving levels and frequencies, whereas between trial changes were always from the same pool of four stimuli. The cost of making two judgments as opposed to only one was measured by comparing performance in the three conditions (judge amplitude, judge frequency, or judge both). The cost of roving levels and frequencies was measured by comparing performance between the two experiments. It was found that two judgments resulted in a decrease in performance only when the rove was not employed. This agrees with findings in the bimodal dual-task suggesting that the cost of dividing attention is a result of the use of long-term memory, and that the sensory-trace does not incur a cost in the dual-task. [Research supported by the Nat. Inst. of Health (NIDCD 07787), USA, Univ. of California, USA, and CNRS, France.]
Dynamic intensity change influences perceived pitch: Attentional differences between musicians and nonmusicians
Authors: Neuhoff John G.
Published: July 2002

The influence of dynamic intensity change on the terminal pitch of ascending frequency glides was tested as a function of terminal frequency and musical experience. Previous work has shown that dynamic intensity change influences perceived pitch [J. G. Neuhoff and M. K. McBeath, J. Exp. Psychol.: Human Percept. Perform. 22, 970–985 (1996)]. In the current study, musicians and nonmusicians were presented with dynamic tones that changed in both frequency and intensity, and made real-time judgments about perceived pitch change. Results show that for both musicians and nonmusicians, the influence of intensity change on perceived pitch lessened as the terminal frequency approached an octave. Musicians were less susceptible to the effects of intensity change for falling intensity but not for rising intensity. The findings suggest that musicians may have better selective attention to dynamic auditory stimulus dimensions, and the influence of a tonal schema may reduce the influence of intensity change on perceived pitch. The results imply an interplay of musical and nonmusical listening strategies and demonstrate that the two are not mutually exclusive.
Junctures in speech communication
Authors: Flanagan J. L.
Published: July 2002

Several junctures in research on speech communication seem salient over the past 50 years. Under the goad of expensive long-distance transmission, and the criticality of voice communication in a world in turmoil, bandwidth compression methods received strong emphasis in the 1940s. Because transoceanic communication was by HF radio, privacy and encryption were also central issues. These incentives resulted in the Channel Vocoder and a variety of offshoots. By the 1960s, digital computers were being deployed widely and sampled-data theory was well established, providing the systems researcher with a new environment for experimentation—one in which concepts could be rapidly simulated and evaluated. Bandwidth compression continued to be a focus, as computer simulation techniques progressed from classical filter emulation to new designs based solely on digital theory. By the 1980s, broadband connectivity (including transoceanic cable) was becoming pervasive and economical enough that emphasis on bandwidth conservation waned. Concomitantly, digital machines were expanding in capability—but were markedly limited by their inability to communicate with human users in natural ways. The focus consequently shifted to human/machine communication—especially by conversational means. As we approach the year 2000, a strong research emphasis remains on human/machine communication—but with expanded aspirations for natural interaction. Computer interfaces with multiple modalities—utilizing sight, sound, and touch in combination—are beginning to serve multiple collaborating users. In the same era, explosive deployment of two technologies—cellular telephony and computer networking—has rejuvenated interest in bandwidth conservation and coding for privacy—with many of the early vocoder concepts evolving to sophisticated digital forms implemented on single-chip processors. As we move toward 2020, a special emphasis is likely to be on multilingual communication. And in this time, continued advances in computing, acoustic signal processing, and language modeling should carry translating telephony far beyond the ‘‘phrase book’’ stage.
4-D modeling of sound propagation in shallow water with anisotropic sediment layers
Authors: Tang X. , Badiey M. , Siegmann W. L.
Published: July 2002

A highly efficient 4-D PE model is developed to study broadband sound propagation at the Atlantic Generating Station (AGS) site. Extensive core data has shown that the sediment at this AGS site consists of multiple layers which vary in both range and azimuth. Consequently, sound propagation in the water column in this area is significantly affected by the complex sediment structure due to the fact that the layered sediment acts like a bandpass filter in which broadband acoustic energy is selectively broken into narrow-band components propagating in different layers, usually referred as sediment mode trapping. The details of the range, azimuth, frequency, and bandwidth dependences as well as their relationships to the sediment structure of such mode trapping effect is numerically explored by performing the 4-D PE model. The empirical orthogonal function representation method is employed to transfer the geoacoustic parameters of the sediment core data into PE inputs. The broadband travel time results at eight different bearings are compared with the existing experimental data. The importance of the 3-D effects is also examined by comparing the numerical results of azimuthal coupled and uncoupled models.
The Hong Kong Cultural Centre halls: Acoustical design and measurements
Authors: Marshall A. Harold , Nielsen Johan L. , Halstead M. Miklin
Published: July 2002

The main performance spaces in the Hong Kong Cultural Centre comprise the Concert Hall, seating 2000 and the Grand Theatre seating 1700. The design of the former is derived from the Christchurch Town Hall which it develops in several important ways, while the latter is a lyric theatre/opera hall with several unique features which are described briefly in this paper. The Centre opened in 1989 following extensive commissioning measurements in the halls. Recently the opportunity has arisen to repeat the measurements using an improved technique in an attempt to document changes following a stage extension. Results from these measurements are compared with the earlier series in each hall. Marshall Day Associates, Auckland, New Zealand was responsible for the room acoustical design of these spaces. [The recent visit to Hong Kong was supported by the Acoustics Research Centre, the Hong Kong Cultural Centre, and the Marsden Fund administered by the Royal Society of New Zealand.]
Interrelationship of musical excellence and acoustical excellence: A case study of the Gewandhaus, Leipzig
Authors: Clements Pamela
Published: July 2002

A study of changes in orchestral performance practice and repertoire in the Altes Gewandhaus and the Neues Gewandhaus (opened 1884) under the conductor Carl Reinecke was performed. A parallel study of changes in orchestral performance practice and repertoire in the Neues Gewandhaus was also performed when Carl Reinecke was succeeded by Arthur Nikisch in 1895. In the first instance, the orchestra and conductor are the same but the hall changes; in the second instance, the orchestra and hall are the same but the conductor changes. Both old and new halls were regarded as outstanding acoustically, but under Reinecke the orchestra’s reputation waned because of conservatism in programming and interpretation. Historical evidence shows that the orchestra went through a difficult period accommodating the new hall’s acoustics and emerged with a new sound. Yet, despite the hall’s excellent acoustics, the orchestra performed better in another, poorer, acoustic environment under the more dynamic conductor Arthur Nikisch. The orchestra only regained its international reputation later when Nikisch became conductor at the Gewandhaus. The study explores Nikish’s response to the hall’s acoustic possibilities, and suggests reasons why a hall with a relatively dry acoustic could be pivotal in the orchestra’s then becoming a foremost interpreter of the late Romantic repertoire.
Acoustical design and the characteristics of Sapporo Concert Hall
Authors: Toyota Yasuhisa , Naniwa Katsuji
Published: July 2002

Sapporo Concert Hall, with 2008 seats in the large hall and 453 seats in the small hall, was opened on July 4, 1997. Both halls were designed for classical music, the large one mainly for orchestral music and the small one for chamber music and recitals. The large hall was designed with the concept of the surrounded stage and ‘‘vineyard steps’’ seating arrangement like Philharmonic Hall in Berlin and Suntory Hall in Tokyo. The emphasized points in acoustical design were as follows: (1) Effective use of the ‘‘vineyard steps’’ walls which were introduced into the audience area to provide the effective early reflections; (2) installation of the big sound reflectors suspended above the stage area to provide the effective early reflections to musicians and audience around the stage; (3) introduction of heavy material, 150-millimeters-thick concrete, into the main ceiling to get enough response in the low frequencies. The small hall was designed as a typical shoebox hall with narrow width and high ceiling. Acoustically tunable curtains were introduced to make the wide range of acoustical possibilities. The results of the acoustical design and its characteristics will be reported.
The best remaining seat
Authors: Vaupel Bodil
Published: July 2002

It is important that an auditorium be designed to have as many good seats as possible. Not all seats in an auditorium are equally good. This is manifested in that the audience does not choose its seats randomly. The audience understands intuitively that, generally speaking, the closer a seat is, and the more straight on, the better it is. Imagine an auditorium with open seating and the audience entering one at a time. People will in turn make a selection of what in their opinion is the best remaining seat. The order in which the seats are chosen is an indicator of the rank order of the desirability of the individual seats. As the audience makes its seat selection, a geometric pattern of the occupied seats unfolds, and reveals the boundary of the preferred seats. The perimeters describe the equal desirability curves and outlines the auditorium plan with as many good seats as possible. The audience choice of seat is recorded by time lapse photography. The data are analyzed in a combined computer drawing and mathematics program. A mathematical model has been developed that evaluates the desirability of the seating in an auditorium from the audience’s point of view.
Simultaneous measurements of room-acoustic parameters using different measuring equipment?
Authors: Halmrast Tor , Gade Anders , Winsvold Bjorn
Published: July 2002

Often the results from different room-acoustic measurements in the same hall disagree, and the disagreement is just said to be due to different measuring equipment, or different rigging/temperature, etc. The room acoustic of the Oslo Concert Hall was measured simultaneously, using the following different measuring equipment: (1) MLS/MLSSA (Statsbygg), (2) Sweep-Tone (Tech. Univ. Denmark), and (3) Norsonic 840 with MLS+MatLab. For some of the measurements (4) Pistol and (5) Electrical Impulse were also used. The paper will compare the results from the different measuring equipment, for the most known room-acoustic parameters. For the reverberation time parameters RT and EDT, very good agreement was found between the three main measuring equipments. For Ts and C80 the agreement between these three is good/fair for the higher frequencies, but less good for the bass, especially C80. The measurements with Electric Pulse and Pistol as signals (analyzed through Norsonic+MatLab) indicate good agreement for the reverberation times, but EDT is somewhat higher for the Pistol. For Ts and C80 the Electric Impulse and especially the Pistol give less clearness (higher Ts and lower C80), compared to MLSSA, Sweep Tone, and Norsonic/MLS.
Are blood clots Biot solids?
Authors: Mourad Pierre D. , Kargl Steven G.
Published: July 2002

Blood clots are saturated porous solids. Their unwanted presence in veins and arteries is the source of a variety of medical problems. Their destruction (thrombolysis) via ultrasound and various enzymes (ultrasound-enhanced thrombolysis, or UET) is still a poorly understood phenomenon. The current view is that cavitation is the mechanism behind UET. This presentation begins with a review of the structure of blood clots and natural thrombolysis. Following that is a review of the literature on UET pointing out that cavitation is at best part of the story, at least in vitro, and more suspect in vivo. Next is a motivation of the Biot theory (a theory for how sound propagates through and interacts with porous solids) and its application to blood clots. The results of the work thus far predict that blood clots are Biot solids, which has implications for understanding UET. [Work sponsored by DARPA.]
A tubular piezoelectric actuator and its characteristic analysis by finite-element modeling
Authors: Wakatsuki Naoto , Tsuchiya Takao , Kagawa Yukio , Hatta Kazumichi
Published: July 2002

Three-dimensional motion is sometimes required in an actuator. A tubular configuration is proposed to realize the three-dimensional motion at the tip. A cylindrical shell piezoceramic, polarized in the radial direction, is provided with several pairs of electrodes on both surfaces of the shell. The combination of the voltages with proper sense makes it possible to control the motion. The displacements or the forces at the tip are expressed in terms of the linear combination of the electrical input voltages on each pair of electrodes. The coefficient of each term is to be determined by the experiment or numerical simulation. Here, the determination of the coefficients is made by finite-element modeling for which the code previously developed is utilized.
Study of compound structured ultrasonic transducer made of PZT/PVDF
Authors: Kim Moo Joon , Kim Dong Hyun , Ha Kang Lyeol
Published: July 2002

When the piezoelectric ceramic, PZT is used in the water it needs matching layers for efficient energy transmission. PZT is known as the proper piezoelectric material for the transmitter by reason of the large electromechanical coupling factor. So actually PZT has been used for the nondestructive testing or ultrasonic diagnostic instrument as good material. In the meantime, there is a kind of polymer by the name of PVDF. Its acoustic impedence is similar to water, so PVDF does not need matching layers but it is not a proper material for the transmitter because of the small electromechanical coupling factor. However, the receiving sensitivity of PVDF is very flat through the wide frequency range. So it is known as a proper material for the receiver like wideband hydrophone. Therefore in this paper it is suggested that the transducer which transmits and receives signals by PZT and PVDF, respectively, could be constructed compositively, and the transmitting and receiving feature of the transducer was investigated theoretically and experimentally.
The use of frequency-dependent velocity scaling as a diagnostic tool
Authors: Quinlan Daniel
Published: July 2002

This paper will discuss a method for investigating broadband aeroacoustic noise sources. The method is based upon the use of frequency-dependent velocity scaling. The dependence of sound power level upon a characteristic velocity is determined experimentally, and that dependence is used as an indicator of primary aeroacoustic processes. The procedure yields an identification of distinct frequency bands within which source trends are observable. Each band is presumed to be controlled by different processes, and the set of likely processes is fixed according to the average velocity exponent value obtained. In principal, the method is applicable to low-speed aeroacoustic source identification problems where a characteristic flow speed can be measured and systematically varied. Measurements of sound radiated by flow over a flat plate were used to evaluate the performance of the method. The procedure was then applied to a small axial fan typical of those used to cool electronic systems. For the fan, the frequency-dependent velocity scaling demonstrated that shifts in dominant aeroacoustic processes occur near 2 kHz and above 4 kHz. The results added insight to a related study which demonstrated that tip gap flows were the primary source of broadband noise above 2 kHz.
Features of Japanese soundscapes recognized by foreigners: A questionnaire survey on sounds for the foreigners living in Fukuoka
Authors: Iwamiya Shin-ichiro
Published: July 2002

A questionnaire survey on odd sounds for foreigners living in Fukuoka was done to clarify the feature of Japanese soundscapes recognized by those whose cultural background is different from the Japanese. The foreigners were asked to point out the sound which they usually heard in Japan but heard less in their home countries and their impressions, and the sound which they usually heard in their home countries but heard less in Japan and their impressions. The traffic sound signal for the blind, the exhaust noise by wild bike riders, the peddlers’ cries, and the election campaign broadcast are the typical sounds only heard in Japan. The foreigners usually have a good image for the traffic sound signal for the blind and the peddlers’ cries. In contrast, they have a negative impression on the muffler noise by wild riders and speeches concerning election. The Japanese soundscape is characterized by these sounds which we hear in daily life. Comparison between the sounds usually heard in Japan and those heard less in Japan shows that there are too many public sounds, such as announcements using public-address systems and music at the shopping centers, and few natural sounds and human voices in Japan.
Single-bubble sonoluminescence and liquid fracture
Authors: Prosperetti A.
Published: July 2002

Attention is drawn to the fact that the very mechanism that traps a bubble in a standing acoustic wave causes it to execute an oscillatory translational motion in the direction of gravity. A bubble driven below resonance will move up during the collapse phase and down during the expansion phase. A bubble translating and collapsing develops a jet in the direction of motion. It is hypothesized that sonoluminescence is due to the collision of this jet with the other side of the bubble surface. The mechanism of light emission is a ‘‘fracture’’ process of the liquid that initially cannot respond by flowing due to the very short rise time of the applied pressure. The picosecond duration of the light flash is the time it takes for the microjet overpressure to be relieved by reflection from the microjet free surface. Several other observed features of sonoluminescence (such as noble gas and temperature sensitivity, anomalous mass loss process, effect of surfactants) can also be explained, at least qualitatively. [Work supported by the Office of Naval Research.]
Radiation acoustics—photoacoustics and acousto-optics of penetrating radiation
Authors: Lyamshev Leonid M.
Published: July 2002

Photoacoustics is a science about optical generation of sound in a substance. The study of light diffraction by acoustic waves is the subject of acousto-optics. Light is a beam of particles, i.e., photons. In this connection the study of sound generation by beams of electrons, protons, neutrons, and other particles in a substance, as well as the study of matter waves’ (particle beams) diffraction by ultrasound may be considered correspondingly as photoacoustics and acousto-optics of penetrating radiation. Combined together, this is the field which got the name of radiation acoustics. It develops at the interface of acoustics, nuclear physics, solid state physics, and physics of high energy and elementary particles [see L. M. Lyamshev, Radiation Acoustics (Nauka-Fizmatgiz, Moscow, 1996), in Russian]. Some universal laws characterizing generation of sound by beams of penetrating radiation are discussed. The problem of acoustic–radiational interaction is considered using the examples of diffraction of x rays and thermal neutrons by ultrasound in solids. [Work supported by RFBR.]
The effects of age and hearing impairment on the time course of backward masking
Authors: Gehr Sara Elizabeth , Sommers Mitchell
Published: July 2002

The present study was designed to assess the effects of age and hearing loss on the time course of backward masking. Thresholds for detecting a 10-ms, 500-Hz tone were measured as a function of the temporal separation between the signal and a 50-ms broadband masker in normal-hearing young listeners (18–25), normal-hearing older adults (65–82), and hearing-impaired older adults. Younger subjects exhibited less initial masking, had steeper recovery functions, and asymptoted closer to their unmasked thresholds than either group of older adults. Comparisons between the normal-hearing and hearing-impaired older individuals indicated a slower time course of recovery from backward masking for listeners with hearing loss. Differences between the two groups of normal-hearing listeners (young and old) suggest that age, independent of hearing loss, affects the temporal course of backward masking. Differences between the normal-hearing and hearing-impaired elderly listeners, however, indicate that age-related hearing impairment may also alter the rate of recovery from backward masking. [Work supported by the Brookdale Foundation and NIA.]
Speech intelligibility and localization in a complex environment by listeners with hearing impairments
Authors: Hawley Monica L. , Litovsky Ruth Y. , Colburn H. Steven
Published: July 2002

Listeners with hearing impairments often complain of difficulties when trying to communicate in a complex environment such as a cocktail party. Explorations of the dependence of the intelligibility and localizability of speech on the number and spatial positions of simultaneous interfering sources are reported on. Target sources are sentences spoken by a female and interfering sources include other sentences or speech-shaped noise. The total number of sources played at any one time varied between one and four. Listeners with normal hearing, profound monaural deafness, and with symmetric sensorineural hearing impairments were tested. Listeners were tested without hearing aids. Previous work in free field and with virtual stimuli has shown that bilaterally hearing-impaired listeners show large intersubject differences in their performance in both speech intelligibility and localization tasks. In the present study an investigation was made to see whether these intersubject differences are related to each listener’s sensitivity to specific binaural cues. Therefore, in addition to localization and speech intelligibility, performance in discrimination of interaural time and level, as well as binaural masking level differences in each listener was measured. The goal of this study is to determine the extent to which performance on speech-based tasks can be accounted for by basic binaural abilities. [Work supported by NIH-NIDCD DC00100.]
Virtual midplane localization of subjects with sensorineural hearing loss
Authors: Simon Helen J. , Aleksandrovsky Inna
Published: July 2002

This paper reports the results of a study that investigated localization performance of simulated externalized signals in sensorineural hearing loss (SNHL) listeners when signals were presented with either unbalanced [equal sensation level (EqSL)] or balanced [equal sound-pressure level (EqSPL)] hearing aid gain at the two ears. In previous reports from this laboratory, it has been found that when equalizing by SL, the perceived lateral position was essentially linearly dependent on the degree and direction of asymmetry in normal-hearing (NH) and SNHL listeners. Equalizing by SPL showed no such dependency. It was hypothesized that the current practice of fitting ‘‘binaural’’ hearing aids in asymmetric SNHL listeners using prescription formulas might result in SPL imbalance which would disrupt the previously adapted system and impair localization. The present study was designed to address this issue by measuring localization using a simulated externalized auditory image combined with head position control of IID and ITD to spatially fix the image. Absolute and signed error deviations from center were analyzed. Significant interactions of group (NH versus SNHL)* frequency and balance (EqSL or Eq SPL)* frequency were found. These data will be discussed in terms of auditory adaptation and strategies of fitting binaural hearing aids. [Work supported by NIDRR.]
Speech intelligibility is highly tolerant of cross-channel spectral asynchrony
Authors: Greenberg Steven , Arai Takayuki
Published: July 2002

A detailed auditory analysis of the short-term acoustic spectrum is generally considered essential for understanding spoken language. This assumption is called into question by the results of an experiment in which the spectrum of spoken sentences (from the TIMIT corpus) was partitioned into quarter-octave channels and the onset of each channel shifted in time relative to the others so as to desynchronize spectral information across the frequency plane. Intelligibility of sentential material (as measured in terms of word accuracy) is unaffected by a (maximum) onset jitter of 80 ms or less and remains high (>75%) even for jitter intervals of 140 ms. Only when the jitter imposed across channels exceeds 220 ms does intelligibility fall below 50%. These results imply that the cues required to understand spoken language are not optimally specified in the short-term spectral domain, but may rather be based on some other set of representational cues such as the modulation spectrogram [S. Greenberg and B. Kingsbury, Proc. IEEE ICASSP (1997), pp. 1647–1650]. Consistent with this hypothesis is the fact that intelligibility (as a function of onset-jitter interval) is highly correlated with the magnitude of the modulation spectrum between 3 and 8 Hz.