bluuebunny/crossref_metadata_2025 huggingface dataset:
Considerations in applying noise cancellation techniques to telephones.
Authors: Nasar Alan S. , Birman Chaim , Raichel Daniel R.
Published: October 2005

The intelligibility of voice transmission through a telephone can be severely affected by the presence of excessive background noise. Accordingly, a system was designed to incorporate an auxiliary microphone into the receiver of an ordinary telephone handset. This microphone is strategically placed to pick up ambient noise. The signal from this microphone is subtracted from that of the receiver through a circuit incorporating three op-amps to produce a signal that contains significantly less background noise than the original signal. The corrected signal is then relayed through the telephone in the same manner as that for the receiver in an ordinary telephone.
Frequency and amplitude of vibration of reeds from American reed organs as a function of pressure.
Authors: Koopman Philip D. , Hanzelka Chad D. , Cottingham James P.
Published: October 2005

The frequency and amplitude of vibration of a representative sample of reeds from American reed organs have been studied as functions of the (negative) static pressure difference between the interior and exterior of the windchest. Over a pressure range that includes the normal playing pressure of the instrument, the frequency tends to decrease in an approximately linear fashion with increasing pressure difference, but some anomalous effects are observed at higher pressures. Effects of constrictions to the airflow, simulating the effect of a partially opened pallet, have also been studied.
Flow noise in automotive heating, ventilation, and air conditioning systems.
Authors: Lauchle Gerald C.
Published: October 2005

Acoustic noise generated by a typical automotive heating, ventilation, and air conditioning (HVAC) system can be dominated by unsteady flow and turbulence. A comprehensive flow field and acoustic field study has been conducted experimentally on a stand-alone HVAC system operating in its maximum air conditioning mode. Acoustic intensity field mapping was conducted in an anechoic environment. Detailed flow visualizations were conducted underwater on an optically clear system operating at prototypical values of the Reynolds number. The blower is the dominant low-frequency source of noise, while at higher frequencies, additional flow noise sources exist. These include high shear regions within the ducting, separated flows off of flow obstructions, and the exit flow from register vents. Flow visualizations of the blower internal flow field were also conducted on a three-times-larger optically clear model of the blower using underwater particle tracking techniques. The results identify significant regions of inefficient flow, such as blade passage flow separation, reentrant flow, and rotating stall. Collectively, these lead to poor aerodynamic performance as well as noise. [Work supported by Ford Motor Co. and is drawn from the thesis research of former students Timothy Brungart, George Denger, Lori Perry, and Mike Sullivan.]
Sparse random ultrasound phased arrays for focal surgery.
Authors: Frizzell Leon A. , Goss Stephen A. , Kouzmanoff Jeffrey T. , Barich Joseph M.
Published: October 2005

The feasibility of using novel ultrasound phased arrays consisting of array elements larger than one wavelength, minimizing the number of elements in an aperture through a combination of geometric focusing, directive beams, and sparse, random placement of array elements, for tissue ablation applications was examined both theoretically and experimentally. A hexagonally packed array consisting of 108 8-mm-diam circular elements mounted on a spherical shell was modeled theoretically, and a prototype array was constructed, to examine the feasibility of sparse random array configurations for focal surgery. A randomly selected subset of elements of the prototype test array (64 of 108 available channels) was driven at 2.1 MHz with a 64-channel digitally controlled rf drive system. The performance of the prototype array was evaluated by comparing field data obtained from theoretical modeling of the array configuration to that obtained experimentally via hydrophone scanning. The results of that comparison, along with total acoustic power measurements, indicate that the use of sparse random phased arrays for focal surgery is feasible, and that the nature of array packing is an important determinant to observed performance. [This research was supported by National Cancer Institute Grant No. CA66462.]
Therapeutic cardiac ultrasound: Ultrasound accelerated thrombolysis, ultrasound angioplasty, and the ‘‘acoustic filter.’’
Authors: Meltzer Richard S.
Published: October 2005

Ultrasound at frequency 1 MHz can accelerate thrombolysis in an in vitro system using streptokinase, urokinase, or t-PA. [C. W. Francis et al., J. Clin. Invest. 90 2063–2068 (1992)]. Ultrasound can also hasten reperfusion due to thrombolytic agents both in vitro [D. Harpaz et al., Am. Heart J. 127, 1211–1219 (1994)] and in vivo [R. Kornowski et al., Circulation 89, 339–344 (1994)]. The mechanism is nonthermal, probably related to cavitation. This type of thrombolysis which is associated with relative low intensity, high-frequency ultrasound is to be distinguished from the high intensity, low-frequency (∼ 20 kHz) ultrasound that has been proposed for ‘‘ultrasound angioplasty’’ [A. Ernst et al., Am. J. Cardiol. 73, 126–132 (1994)]. Potential clinical applications and problems and limitations to the clinical application of ultrasound accelerated thrombolysis and ultrasound angioplasty will be discussed. An ‘‘acoustic filter’’ has been developed with the goal of removing microbubbles from cardiopulmonary bypass equipment, preventing neurologic damage [K. Q. Schwarz et al., J. Thorac. Cardiovasc. Surg. 104, 1647–1653 (1992); US Patent No. 5,334,136, 2 August 1994].
Effects of source spectrum irregularity and uncertainty on sound localization.
Authors: Macpherson Ewan A.
Published: October 2005

Localization performance has been shown to deteriorate when source spectra are variable, but the few studies investigating this have confounded trial-to-trial variability with spectral irregularity present in each stimulus. In this experiment these factors were varied independently. Blindfolded listeners seated in an anechoic chamber reported the apparent locations of wideband noise bursts having either smoothly sloping spectra or 1/3-oct scrambled spectra. The spectra were either varied from trial to trial or held constant throughout an experimental session. Localization performance was compared to that obtained in a baseline condition using flat-spectrum stimuli. Despite trial-to-trial uncertainty, performance with the smoothly varying spectra was equivalent to baseline. The responses to the majority of the scrambled spectrum stimuli were similar to baseline, but pronounced bias and elevated variability were observed at certain pairings of source spectrum and location that varied between listeners. The degree of uncertainty had no substantial effect on performance with these stimuli. The results suggest that source spectrum familiarity cannot effectively compensate for the interference of spectral irregularity with the processing of spectral localization cues. However, this processing appears to be surprisingly immune to such interference over much of auditory space. [Work supported by NIDCD.]
Dichotic pitches as illusions of binaural unmasking.
Authors: Culling John F. , Summerfield Quentin , Marshall David. H.
Published: October 2005

Dichotic pitches are binaural perceptual phenomena which occur when broadband noise with specific interaural phase/time relationships is presented simultaneously to the two ears. Four dichotic pitches have been described: Huggins’ pitch; the binaural edge pitch; the Fourcin pitch; the dichotic repetition pitch (DRP). This paper shows that the perceived pitch and timbre of the first three dichotic pitches are correctly predicted using a model of binaural unmasking [Culling and Summerfield, J. Acoust. Soc. Am. 98, 785–797 (1995)]. The model detects across-frequency variations in interaural correlation; the resulting central spectrum shows peaks which correspond to the frequencies listeners hear. These pitches are probably, therefore, illusions produced by the mechanism of binaural unmasking. The DRP is not predicted by the model. The DRP could be produced through binaural cross talk, but experiments using insert earphones which produce minimal cross-talk confirmed that the phenomenon persists when cross talk is effectively eliminated. The DRP is probably, therefore, produced by a separate mechanism from the other dichotic pitches.
Binaural detection with spectrally nonoverlapping signals and maskers.
Authors: van der Heijden Marcel , Trahiotis Constantine , Kohlrausch Armin , van de Par Steven
Published: October 2005

Thresholds were measured for diotic tonal signals masked by interaurally delayed bands of Gaussian noise. When the signal frequency was 525 Hz, the spectrum of the masker was either below (highest frequency, 450 Hz) or above (lowest frequency, 600 Hz) the frequency of the signal. With a 450-Hz signal, the spectrum of the masker was always above the signal frequency (lowest frequency, 600 Hz). Signals had a 250-ms duration and were temporally centered within 300-ms-long maskers. The spectrum level of the maskers was 60 dB. Masked thresholds obtained in all three conditions varied sinusoidally with the interaural delay of the masker. The periodicities within the data were close to, but not identical with, the periodicities of the signals (not the maskers). This outcome is discussed in terms of (1) auditory distortion products stemming from interactions within the masking bands of noise [cf. van der Heijden and Kohlrausch, J. Acoust. Soc. Am. 98, 3125–3134 (1995)], and (2) binaural models incorporating internal delay mechanisms. It is shown that using such spectrally nonoverlapping signals and maskers can help test interesting hypotheses concerning binaural models. [Work supported by Grant No. 5 RO1 DC00234-13 from the National Institute of Deafness and other Communication Disorders, NIH.]
Localization and speech perception in noise by aging listeners.
Authors: Bilger Robert C. , Meyer Ted A.
Published: October 2005

Presbycusic listeners are reported to have difficulty hearing speech in noisy sound fields. To resolve the issue of whether this difficulty is central or peripheral, an experiment, in which the spectrum of a masking noise was manipulated to replace acoustics that a listener’s peripheral hearing loss filtered out of the input, was conducted. The experimental listeners were 12 people with high-frequency hearing loss who were 65 years of age or older (5 women/7 men) and the controls were 12 young adults with normal hearing (8 women/4 men). When PB words (200 words/condition) were presented at 65 dB SPL in a flat noise (S/N = 0 dB) at zero azimuth, the controls scored 53.9% correct and, when the speech and noise were separated by 90°, their score was 70.2% correct, an increase of 16.3% Under the same experimental conditions, the experimental listeners scored 44.8% correct for signal and noise at zero azimuth and 53.4% correct for 90° separation, an increase of only 8.6% When the noise presented to the experimental listeners was filtered to match their equal-loudness contours (high-frequency boost), however, their speech recognition improved to 59.5%, an increase of 14.7% over their mean score for no separation of signal from noise, evidence that their difficulty is of peripheral origin. [Work supported by DC 00174-11.]
Detection and identification of environmental sounds.
Authors: Watson Charles S. , Kidd Gary R. , Gygi Brian
Published: October 2005

Most studies of auditory recognition and identification have employed either speech stimuli or nonspeech sounds generated in the laboratory (e.g., tones of various frequencies, tonal patterns, click trains). The present study employed 25 naturally occurring complex sounds (obtained from a commercial sound-effects library), such as those produced by doors closing, babies crying, helicopters in flight, and other familiar events. These sounds, equated for peak levels, were recorded with a background of broadband noise. The recorded sounds were presented to groups of six to eight listeners in both open- and closed-set formats (with the list of responses displayed continuously in the latter). Confusion matrices were generated using a wide range of event-to-noise (Ev/N) ratios. Two frequent confusions were identified for each item, and were used to create a three-alternative forced-choice test. Eight values of Ev/N were selected for each item in an effort to achieve uniform item identifiability. Average Ev/N required to achieve 50-percent-correct recognition, the slopes of psychometric functions, and the distribution of these measures among normal-hearing listeners are compared to the corresponding measures for speech identification. [Work supported by AFOSR and NIDCD.]
Target weights for high-frequency SAM targets and distractors lateralized on the basis of envelope delay.
Authors: Dye R. H.
Published: October 2005

The extent to which judgments of the laterality of SAM high-frequency carriers is influenced by other SAM tones was assessed in a stimulus-classification paradigm. The target was either a 4- or a 2-kHz tone modulated at 200 Hz, and the distractor was a 2- or 4-kHz tone modulated at rates ranging from 50 to 400 Hz. Of particular interest is the manner in which the weight given to the target is dependent upon the carrier and modulation frequencies. On each trial, the target was presented with one of ten envelope delays, as was the distractor. Each test interval was preceded by a diotic presentation of the target alone. The relative contributions of the envelope delays of the target and the distractor were assessed by the point-biserial correlations between the target/distractor delays and the type of response elicited (‘‘left’’/‘‘right’’). Although substantial individual differences were found in terms of which carrier was more potent and in how target weight depended upon modulation frequency, the relationship between target weight and modulation frequency tended to be the same for the two carrier frequencies for a given listener.
A comparison of the effects of active noise reduction and conventional hearing protectors on auditory perception in normal and hearing-impaired listeners.
Authors: Abel Sharon M. , Spencer Deborah L.
Published: October 2005

The relative benefit of active noise reduction (ANR), compared with conventional hearing protection, was assessed. Two groups of normal-hearing subjects, differing in age, and one group with bilateral sensorineural hearing loss participated. Subjects were tested with the ears unoccluded, and fitted with E-A-R foam plugs, E-A-R HI-FI plugs, Bilsom Viking muffs, and Peltor 7004 muffs with ANR capability. The E-A-R foam plug provided the highest, and the E-A-R HI-FI plug the lowest, real-world sound attenuation, from 250 Hz to 8 kHz. The Bilsom and Peltor muffs were midway and virtually identical. ANR reduced sound levels by an additional 10 dB at 250 Hz. In normal listeners, protectors improved word recognition in noise but there was no difference due to the device. In impaired listeners, performance in quiet was significantly better with the ears unoccluded or fitted with the E-A-R HI-FI plugs than with the other conventional devices. ANR was midway. In noise, performance was relatively best with ANR and worst with the ears unoccluded. Within group, there were no differences in either duration of frequency difference limens, across conditions. Protected frequency DLs were significantly greater for the impaired group. The results support considering both hearing status and task in assessing hearing protectors. [Work supported by National Defence Canada.]
Predicting custom hearing aid circuit selection success from field returns analysis.
Authors: Preves David A. , Leisses Mary E.
Published: October 2005

A wide variety of signal processing circuitry is available from hearing aid manufacturers for use in custom hearing aids. Whether the type of circuit used is specified by the clinician or by the manufacturer, the selection process is often speculative because of the lack of understanding about how different types of signal processing interact with pathological auditory systems. An empirical approach to signal processing selection is proposed based on the circuit that is most likely to minimize field returns for a particular audiometric configuration, degree of loss, and hearing aid model. Several thousand ITE and ITC hearing aid fittings made by one hearing aid manufacturer were monitored via a computerized field tracking data base for incidence of repairs and returns for credit. Circuits included four types of signal processing having class D output stage: linear, input compression, TILL, and BILL. Audiograms were divided into seven configurations: flat, gradually sloping, steeply sloping, precipitous, rising, cookie bite, and inverted cookie bite. The database was entered into the IDIS artificial intelligence program, and design rules were formulated to maximize fitting success. From these rules, signal processing type(s) were identified for each audiometric configuration that would minimize field returns.
Robust feedback control of flow–induced structural radiation of sound.
Authors: Heatwole Craig , Franchek Matthew A. , Bernhard Robert J. , Mongeau Luc
Published: October 2005

A significant component of the interior noise of aircraft and automobiles is a result of the turbulent boundary layer excitation of the vehicular structure. In this investigation the feasibility of active control of wind noise is studied. Initial studies are made by considering the idealized case of sound radiation from a simply supported panel excited by a turbulent flow boundary layer. To study various control system alternatives, a wind noise model is developed. The model consists of a modal model of the excitation of a plate from a turbulent boundary layer, a model of plate vibrations, and a model of the sound radiated from the plate. A frequency-domain approach, similar to quantitative feedback theory, is utilized in the design of a robust feedback controller. The controller utilizes plate acceleration feedback while maintaining sound-pressure-level reduction as the primary design objective. The design method insures that performance and control effort objectives are met for plant and disturbance uncertainty. The controller design method offers flexibility in configuring the size of the controller, and the effect of the performance and control effort objectives on the controller design are easily identified.
An experimental study of active control of vibration transmission in a cylindrical shell.
Authors: Pan Xia , Hansen Colin H.
Published: October 2005

An experimental investigation of active control of vibratory power transmission in a semi-infinite cylinder, using an array of electrodynamic shakers, is described. The cylinder was mounted vertically in a sand-filled box (1 m in height) in an attempt to provide a semianechoic termination at one end. The other end was simply supported using a steel ring. The cylinder was excited near the simply supported end using a primary shaker. Control was implemented using three control shakers applied downstream from the primary shaker. Using three control shakers it is possible to achieve a 7-dB reduction in power transmission. Although 7 dB was the maximum power reduction which could be obtained for the experimental equipment, the numerical simulation shows that on a large scale, a reduction of 30 dB could be obtained. Also, measurement of power transmission intensity in a cylinder using two accelerometers was investigated. The results indicate a means of simplifying power transmission measurements in large cylindrical structures.
Internal–external measurement of three-dimensional velocities of a submerged shell by optical vibrometry.
Authors: Vignola Joseph , Frank P. , Leka L. , Simpson Harry , Houston Brian H.
Published: October 2005

A unique experimental capability for measuring both the interior and exterior three-axis surface motions of a completely submerged ribbed cylindrical shell has been developed. This system is composed of two three-dimensional laser Doppler vibrometers positioned by a pair of high-precision robots. The two vibrometers work together to measure the three-components of velocity up to 50 kHz on both the interior and exterior cylinder surfaces. For the interior, a compact three-dimensional vibrometer was designed and constructed to operate in conjunction with a cylindrical-based scanner mounted to the stiff endcaps of the shell. This scanning system is capable of positioning the laser vibrometer with a precision of +/− 3 mil over 100% of the interior cylinder surface. A second three-dimensional laser vibrometer designed for exterior (in-water) operation was constructed and integrated into the NRL near-field acoustic holography system. This large workspace Cartesian-based scanner is capable of collocating the focal point of the exterior vibrometer with that of the interior to within +/− 10 mil. The design of the system will be discussed, and structural acoustic data will be presented from a series of preliminary experiments conducted to evaluate the performance of the system.
Propagation of signals from strong explosions above and below the ocean surface.
Authors: Clarke Douglas B. , Piacsek Andrew A. , White John W.
Published: October 2005

In support of the Comprehensive Test Ban, research is underway on the long-range propagation of signals from nuclear explosions in the deep underwater sound (SOFAR) channel. Our work has emphasized the variation of wave properties and source region energy coupling as a function of height or depth of burst. Initial calculations on CALE, a two-dimensional hydrodynamics code developed at LLNL by Robert Tipton, were linked at a few hundred milliseconds to a version of NRL’s weak shock code, NPE, which solves the nonlinear progressive wave equation [B. E. McDonald and W. A. Kuperman, J. Acoust. Soc. Am. 81, 1406–1417 (1987)]. The wave propagation simulation was then followed down to 5000-m depth and out to 10 000-m range. In the future, calculations on a linear acoustics code will extend the propagation to greater distances. Until recently our research has considered only explosions in or above the deep ocean. New results on energy coupling and signal propagation in shallow water and the effects of other improvements will be presented. [Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48.]

Standards Committee S2 on Mechanical Vibration and Shock. Working group chairs will present reports of their recent progress on writing and processing various shock and vibration standards. There will be a report on the interface of S2 activities with those of ISO/TC 108 (the Technical Advisory Group for ISO/TC 108 consists of members of S2, S3, and other persons not necessarily members of those committees), including a report on the activities of ISO/TC 108, with the plans for its September 1996 meeting in Sydney, Australia. Scope of S2. Standards, specifications, methods of measurement and test, and terminology in the fields of mechanical vibration and shock, and condition monitoring and diagnostics of machines, but excluding those aspects which pertain to biological safety, tolerance and comfort.
The influence of directivity on sound heard by an audience during an orchestral performance.
Authors: Meyer Jürgen
Published: October 2005

For a listener seated in a hall, sound impressions are created by the time structure and the intensity ratios of direct sound, early reflections, and reverberation. The intensity ratios between these components depend on the directivity of the sound generated by different instruments. Even for high-pitched instruments, omnidirectional radiation is found only at frequencies below 500 Hz. The strength of the directivity can be described by the statistical directivity factor which fixes the angle-dependent reverberation radius of a source sounding in a hall. For directions of main radiation at upper string frequencies it is of the order of 2–3; for the woodwinds, it is a little lower; for the brasses it exceeds 4. Directions of strong radiation oriented toward the sidewalls, thus supporting the space impression, are found with the strings, bassoons, horns, and trombones. High-frequency components of strings are radiated in strong measure against the ceiling: These reflections support the brilliancy. These sound effects will be demonstrated with a real orchestra.
The study of individual differences in the auditory system.
Authors: McFadden Dennis
Published: October 2005

Individual people often produce reliably different results on various auditory tests even when all have nominally normal hearing. An emerging topic in hearing research is the origins of these individual differences in normal-hearing people. Examples of procedures used to measure the potential contribution of genetics and hormone exposure to individual differences will be discussed, and several examples of a special instance of individual differences in hearing–sex differences–will be described. Of considerable value for the ultimate understanding of individual differences are situations in which subsets of people differ in a similar way across different auditory measures because covariations of this sort have the potential to reveal common underlying mechanisms.
The duality of the observer and the observed—From quantum mechanics to architectural acoustics.
Authors: Beyer Robert T.
Published: October 2005

In 1928, Niels Bohr pointed out the dual description required in the quantum mechanics of measurement, involving the observer and the observed [Naturwissenschaften 17, 483–486 (1928)], and a few years later, John von Neumann discussed this principle at some length in his text on the Mathematical Foundations of Quantum Mechanics [(Springer-Verlag, Berlin, 1932), English translation, Princeton U.P., 1955]. It now appears that architectural acoustics has been following the same route. Examples cited by von Neumann are described and paralleled with examples from the work of Schroeder, Ando, and others in concert hall acoustics.
Comparative study of modular and standard construction methods for broadcast/recording studio applications.
Authors: Michalek David , Tinianow Brandon
Published: October 2005

Consultants and owners are becoming increasingly aware of the choice between modular versus conventional construction methods when designing or remodeling broadcast and recording studios. In a laboratory environment the physical attributes such as acoustic isolation, direct material costs, physical weight, etc. have been quantified and the resulting cost per dB of attenuation determined. When assessing the method to be employed, the less obvious yet vital differences often overlooked include the consultants’ added liability associated with conventional construction methods (risk of failure of acoustical isolation), supervision required during construction to insure attention to critical sound isolation details, durability, installation time, shortage of qualified workmen, fit and finish, exposure to unexpected on-site delays, ability to retrofit, or relocate, etc. These design and cost considerations will be compared and contrasted.
Geographic and seasonal variation in blue and finback whale vocalizations.
Authors: Mellinger David K. , Clark Christopher W.
Published: October 2005

The U.S. Navy maintains a network of listening arrays for detection of submarines. For several years, some of the sounds from these arrays have been made available to scientists for study of cetacean movements and vocalizations. Here the vocal behavior of blue (Balaenoptera musculus) and finback (B. physalus) whales are analyzed. These species produce long sequences of calls, lasting hours to days, that exhibit several types variation across areas of the North Atlantic and Pacific. Finback produce two commonly heard general types of calls, with other types present less frequently. Finbacks in different geographic areas exhibit variations in frequency, in intercall timing, in the mixture of call types, in patterns of calls and silences, and in other ways. Blue whales, unlike finbacks, show distinctly different vocalizations in the Atlantic and Pacific; but like finbacks, both Atlantic and Pacific whales have two principal call types, with different mixtures of the types in different areas. Differences in timing and frequency are heard in distinct areas, with certain patterns heard only in one or a few areas. [Work supported by ONR.]
Practical implications of micromachined ultrasonic transducers.
Authors: Ladabaum Igal , Khuri-Yakub Butrus T.
Published: October 2005

Micromachined ultrasonic transducers capable of airborne transmission of 1- to 12-MHz ultrasound have been reported. It has also been reported that these transducers should enable ultrasonic systems with 100 dB of dynamic range. A justification of the predicted dynamic range involves the careful consideration of the thermal noise limits of the system. Such analysis is developed and is based on the fluctuation dissipation theorem. In addition, the first scans produced with the new transducers are presented along with interpretations of their significant impact to nondestructive testing. Pictures of surface and bulk defects in composites and metals are included. Finally, the fabrication process is summarized and the issues involved in the development of immersion transducers are highlighted. [Work supported by the U.S. Office of Naval Research.]
Noise: Progress report and discussion on the continuing activity of ASA’s role in noise and its control.
Authors: Brooks Bennett M. , DuBois T. James , Hoover Robert M. , Maling George C. , Sutherland Louis C.
Published: October 2005

A discussion meeting sponsored by TC Noise is being held to review progress on activity underway or proposed. Highlighted will be a summary of an all-day seminar on plant and product noise control, led by Dr. Luc Mongeau, to be presented Friday, May 17 to industrial engineers, designers and planners invited to this outreach effort by ASA. The report will also include an update on hearing testing activity, presentations on noise and acoustics to school classes by task group and other ASA members and the status of a joint proposal by ASA and INCE submitted to the Society of Automotive Engineers to add a noise element to their continuing award-winning series of ‘‘World in Motion’’ educational packages to promote science and mathematics literacy for grades 6–8. The report will also include discussion on inadequate acoustic environments in school classrooms and the resulting potential for negative impact on the learning process for children. In discussions with Stanley L. Ehrlich, president-elect of ASA and Dana S. Hougland, chair of TC Architectural Acoustics, Robin M. Towne proposed this topic as worthy of ASA involvement. Thus members of TCAA and other interested persons are also encouraged to attend this session.
Nonlinear acoustic nondestructive testing of cracks.
Authors: Sutin Alexander M.
Published: October 2005

This paper is a review of new nonlinear acoustic methods. Acoustic imaging and NDT methods are widely used in various tecnical fields. Conventional methods are based on the principles of linear acoustics: Nonlinear distortions are ignored. The strength of the distortion can highly increase due to the compliant features of the cracks. Such distortion can be observed by using different nonlinear effects such as high-harmonic generation, modulation of sound by vibrations, and subharmonic generation. Nonlinear acoustic methods are based on these effects and examples of its usage are varied. First, a similar method was developed which tested the glue quality of thermoprotective covers of the Russian Buran space shuttle. Using a nonlinear effect of high-frequency sound modulation by vibrations, an enormous increase of the acoustic nonlinear parameter in steel that has been fatigued has been experimentally demonstrated. The single microcracks in metal construction were detected as well. The method based on second-harmonic generation due to cracks was tested in firm ‘‘PECHINEY’’ in France. The sensitivity of nonlinear new methods to the appearance of fatigue damage to the material is much larger than that of conventional methods of NDT. [Work was supported by Russian Foundation of Fundamental Research Grant N0-93-05-8074.]
Acoustic streaming in a resonant channel.
Authors: Gopinath Ashok
Published: October 2005

The problem of acoustic streaming in a plane parallel channel supporting a resonant standing acoustic wave is considered. The channel is representative of one of the multitude of channels typically present in the stack of a thermoacoustic engine. The governing equations for the flow field in the channel are developed in a generalized dimensionless form which allows for compressibility effects in the fluid, and also for thermal effects due to wall-fluid coupling to be treated. It is verified that for gaps wide with respect to the thermal penetration depth (y0/δκ≫1, y0: channel gap half-width, δκ: thermal penetration depth), the classic results of Rayleigh, including the recent modifications to it [Q. Qi, J. Acoust. Soc. Am. 94, 1090–1098 (1993)], are recovered. However for cases where y0 and δκ are comparable, as in the stack of a thermoacoustic engine, the situation is considerably different and indicates the presence of strong steady streaming flows in the channel which could provide an explanation for the jets experimentally observed at the ends of such a channel as reported at an earlier meeting [Gaitan et al., J. Acoust. Soc. Am. 96, 3220(A) (1994)]. Steady flows of this type have an important bearing on the design of heat exchangers located at the ends of the stack in a thermoacoustic engine.
Stimulus fluctuations in auditory intensity discrimination.
Authors: Goldstein Julius L.
Published: October 2005

A basic prediction of Green’s [J. Acoust. Soc. Am. 32, 121–131 (1960)] classical energy-detection theory for Gaussian signals is a variance measure of stimulus fluctuation that decreases monotonically with the signal’s duration-bandwidth product (TW). Experiments on intensity discrimination of narrow-band Gaussian noise provide the most direct support of this prediction for TW<∼16, but indicate a need for another source of fluctuation for larger TW which could reflect internal noise [deBoer, J. Acoust. Soc. Am. 40, 552–560 (1966)]. An alternative solution is proposed based on detection of the largest waveform peak within the analysis window (≥T). Investigation of this detector for narrow-band Gaussian noise shows that the variance (in dB) of the peak fluctuations is the sum of the variances of the classical energy fluctuation and of a waveform fluctuation due to random phases. For TW<20 the energy fluctuation dominates, while the waveform fluctuation dominates for larger TW. Predictions of the classical energy detection model with an internal noise of 1 dB are essentially indistinguishable from the peak detector model for intensity discrimination thresholds of narrow-band Gaussian noise; however, peak detection explains a wider range of experiments [Goldstein, J. Acoust. Soc. Am. 98, 2907(A) (1995)].
Mechanisms of FM detection.
Authors: Moore Brian C. J. , Sek Aleksander
Published: October 2005

In experiment 1, thresholds for detecting FM were measured for carrier frequencies fc from 0.25 to 6 kHz and for modulation rates fm from 2 to 20 Hz, using a 2AFC task. To disrupt cues based on changes in the excitation pattern, thresholds were also measured when the carriers in both intervals of a trial were amplitude modulated at the same rate as the FM with a modulation index of 0.333. The phase of the AM relative to the FM was randomized. For fc<4 kHz, the deleterious effect of the AM increased with increasing fm. For fc=6 kHz, the effect was independent of fm. In experiment 2, psychometric functions were measured for detecting combined FM and AM, with fm=2 Hz, as a function of the relative phase of the modulators, using modulation depths for AM and FM that would be equally detectable if each were presented alone. Relative modulator phase had no effect for fc=0.25 kHz, small effects for fc=1 kHz, and large effects for fc=6 kHz. The results suggest that a temporal mechanism dominates FM detection for fc<4 kHz, and for fm=2 Hz. A place mechanism dominates for high carrier frequencies, and for lower carrier frequencies when fm≥10 Hz.
Air samples versus biomarkers for epidemiology
Authors: Lin Y S , Kupper L L , Rappaport S M
Published: October 2005

Background:It has been speculated on theoretical grounds that biomarkers are superior surrogates for chemical exposures to air samples in epidemiology studies.

Methods and Results:Biomarkers were classified according to their position in the exposure-disease continuum—that is, parent compound, reactive intermediate, stable metabolite, macromolecular adduct, or measure of cellular damage. Because airborne exposures and these different biomarkers are time series that vary within and between persons in a population, they are all prone to measurement error effects when used as surrogates for true chemical exposures. It was shown that the attenuation bias in the estimated slope characterising a log exposure-log disease relation should decrease as the within- to between-person variance ratio of a given set of air or biomarker measurements decreases. To gauge the magnitudes of these variance ratios, a database of 12 077 repeated observations was constructed from 127 datasets, including air and biological measurements from either occupational or environmental settings. The within- and between-person variance components (in log scale, after controlling for fixed effects of time) and the corresponding variance ratios for each set of air and biomarker measurements were estimated. It was shown that estimated variance ratios of biomarkers decreased in the order short term (residence time ⩽2 days) > intermediate term (2 days < residence time ⩽2 months) > long term biomarkers (residence time >2 months). Overall, biomarkers had smaller variance ratios than air measurements, particularly in environmental settings. This suggests that a typical biomarker would provide a less biasing surrogate for exposure than would a typical air measurement.

Conclusion:Epidemiologists are encouraged to consider the magnitudes of variance ratios, along with other factors related to practicality and cost, in choosing among candidate surrogate measures of exposure.
Historical limitations of determinant based exposure groupings in the rubber manufacturing industry
Authors: Vermeulen R , Kromhout H
Published: October 2005

Aims:To study the validity of using a cross-sectional industry-wide exposure survey to develop exposure groupings for epidemiological purposes that extend beyond the time period in which the exposure data were collected.

Methods:Exposure determinants were used to group workers into high, medium, and low exposure groups. The contrast of this grouping and other commonly used grouping schemes based on plant and department within this exposure survey and a previously conducted survey within the same industry (and factories) were estimated and compared.

Results:Grouping of inhalable and dermal exposure based on exposure determinants resulted in the highest, but still modest, contrast (ε ∼ 0.3). Classifying subjects based on a combination of plant and department resulted in a slightly lower contrast (ε ∼ 0.2). If the determinant based grouping derived from the 1997 exposure survey was used to classify workers in the 1988 survey the average contrast decreased significantly for both exposures (ε ∼ 0.1). On the contrary, the exposure classification based on plant and department increased in contrast (from ε ∼ 0.2 to ε ∼ 0.3) and retained its relative ranking overtime.

Conclusions:Although determinant based groupings seem to result in more efficient groupings within a cross-sectional survey, they have to be used with caution as they might result in significant less contrast beyond the studied population or time period. It is concluded that a classification based on plant and department might be more desirable for retrospective studies in the rubber manufacturing industry, as they seem to have more historical relevance and are most likely more accurately recorded historically than information on exposure determinants in a particular industry.
Primary osteoarthritis of hip, knee, and hand in relation to occupational exposure
Authors: Rossignol M , Leclerc A , Allaert F A , Rozenberg S , Valat J P , Avouac B , Coste P , Litvak E , Hilliquin P
Published: October 2005

Aim:To identify occupations with excess prevalence of osteoarthritis of the knee, hip, and hand in a nationwide survey and to compare occupations with and without excess prevalence with regard to biomechanical stresses and severity of osteoarthritis.

Methods:Patients presenting with osteoarthritis of the knee, hip, or hand were recruited throughout France by their treating physician who collected information on history, including age at onset, occupation, and occupational stresses to joints. Severity was assessed using joint specific functional status questionnaires: Lequesne for the hip and knee and Dreiser for the hand. The distribution of osteoarthritis patients by occupation was compared with the distribution of occupations in all workers in France to obtain prevalence rate ratios.

Results:Occupations with the greatest prevalence rate ratio were female cleaners (6.2; 95% CI 4.6 to 8.0), women in the clothing industry (5.0; 95% CI 3.9 to 6.3), male masons and other construction workers (2.9; 95% CI 2.6 to 3.3), and agriculture male and female workers (2.8; 95% CI 2.5 to 3.2). A twofold greater prevalence rate was observed within certain occupations between self-employed and salaried workers. Early onset of osteoarthritis was seen in the more heavy labour jobs with almost 40% of patients reporting their first symptoms before the age of 50.

Conclusion:The early onset and severity of osteoarthritis in certain occupations warrants an urgent need for occupation specific studies for the development and evaluation of preventive strategies in this leading cause of disability in Western countries.
Cancer incidence among Danish seafarers: a population based cohort study
Authors: Kaerlev L , Hansen J , Hansen H L , Nielsen P S
Published: October 2005

Aims:Seafarers aboard oil and chemical tankers may be exposed to many chemicals, including substances like benzene that are known to be carcinogenic. Other seafarers are exposed to engine exhaust, different oil products, and chemicals used aboard and some years ago asbestos was also used extensively in ships. The aim of this study was to study cancer morbidity among Danish seafarers in relation to type of ship and job title.

Methods:A cohort of all Danish seafarers during 1986–1999 (33 340 men; 11 291 women) registered by the Danish Maritime Authority with an employment history was linked with the nationwide Danish Cancer Registry and followed up for cancer until the end of 2002. The number of person years at risk was 517 518. Standardised incidence ratios (SIR) were estimated by use of the corresponding national rates.

Results:The SIR of all cancers combined was higher than expected: 1.26(95% CI 1.19 to 1.32) for men and 1.07(95% CI 0.95 to 1.20) for women. This was mainly due to an excess of cancer of the larynx, lung, tongue, mouth, pharynx, oesophagus, pancreas, kidney, urinary bladder, colon, and bone as well as skin melanomas among men (the three latter borderline significantly increased), and an excess of cancer of the lung, rectum, and cervix uteri among women. The differences in risk pattern for lung cancer between the different job categories among men ranged in terms of SIR from 1.2 (95% CI 0.9 to 1.7) (engine officers) to 2.3 (1.6 to 3.3) (engine room crew), and 4.1 (2.1 to 7.4) among maintenance crew. Non-officers had a 1.5 times higher lung cancer risk than officers. No increased occurrence of all lymphatic and haematopoietic malignancies combined was found for employees on tankers, but the number of cases was limited to a total of 7.

Conclusions:Danish seafarers, especially men, face an increased overall cancer risk, in particular a risk for lung cancer and other tobacco associated cancers.
Overexpression of OSBP-related protein 2 (ORP2) in CHO cells induces alterations of phospholipid species composition
Authors: Käkelä Reijo , Tanhuanpää Kimmo , Laitinen Saara , Somerharju Pentti , Olkkonen Vesa M
Published: October 2005

We have previously shown that overexpression of human OSBP-related protein 2 (ORP2) in Chinese hamster ovary (CHO) cells results in increased efflux and reduced esterification of cholesterol. The ORP2-expressing cells also have a reduced level of triacylglycerols. We investigated the effects of ORP2 expression on the phospholipid (PL) molecular species and the neutral lipid (NL) fatty acid composition of CHO cells cultured in the presence or absence of serum lipoproteins. In the presence of lipoproteins, ORP2/CHO cells display an increase in polyunsaturated PL species, and polyunsaturated fatty acids (PUFA) in the diminished NL pool are reduced. The increase of polyunsaturated PL may represent a compensatory response to alterations in cholesterol metabolism. Upon lipoprotein deprivation, the ORP2/CHO cells display a drop in polyunsaturated and an increase in mono and diunsaturated PL species. Our results suggest that this is due to defective recycling of PUFA from the diminished NL pool to PL. Furthermore, the PL PUFA, which are elevated in ORP2/CHO cells, are most likely subject to more rapid turnover than the NL-associated pool. The results provide evidence for a delicate integration of cholesterol, PL, and NL metabolism and a role of ORP2 as a regulator of the cellular lipidome.Key words: cholesterol metabolism, mass spectrometry, neutral lipid, oxysterol binding protein, phospholipid, polyunsaturated fatty acid.
Functional analysis of tunicamycin-inducible gene A polypeptide fromAspergillus niger
Authors: Liang Yurong , Li Wei , Ma Qing , Zhang Yuying
Published: October 2005

Tunicamycin-inducible gene A polypeptide (TIGA) is a member of the protein disulfide isomerase (PDI) family and is suggested to facilitate the folding of nascent polypeptides. The functional properties of TIGA were investigated here. TIGA acted as an isomerase, catalyzing the refolding of denatured and reduced ribonuclease A. TIGA also exhibited chaperone activity in the refolding of denatured prochymosin but not in the refolding of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), indicating that it had substrate specificity with respect to chaperone activity. Detailed study with a series of thioredoxin-motif (trx-motif) mutants revealed that the 2 trx-motifs of TIGA were not equal in activity. The N-terminal trx-motif was more active than the C-terminal trx-motif, and the first cysteine in each trx-motif was necessary for isomerase activity.Key words: tunicamycin-inducible gene A polypeptide (TIGA), protein disulfide isomerase, chaperone, protein refolding.