bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of continuous, random onset, and high frequency noise on embryo development in mice
Authors: Nawrot P. , Cook R. O. , Hamm C. W. , Staples R. E.
Published: October 2005

Significant adverse effects on the course of embryo development have been reported in several mammalian species after exposure to high levels of “noise” during pregnancy in some, but not all studies conducted. An investigation was conducted to determine whether the characteristics of different noise exposure paradigms contributed significantly to this variability. Accordingly, three differing paradigms thought to be representative of a wide range of noises were devised to simulate (1) semi-continuous exposure to extremely high levels (126 dBA jet engine run-up noise), (2) unanticipated high intensity startling sounds (microprocessor controlled pseudorandom onset, fast rise time alarm bells, sonalert type warning devices, or jet engine noise each at 112 dBA), (3) very high frequency sound to compensate for the upward frequency shift in rodents' hearing relative to humans (18'20 kHz modulated tones at 110 dB form a commercial rodent repelling device). Pregnant females were divided into groups exposed before or after embryo implantation and their fetuses were examined before term. Preimplantation exposure resulted in decreased pregnancy maintenance and embryo lethality, but teratogenic effects were not noted. Effects differed little between noise exposure paradigms.
Changes in the fetal noise environment due to noise
Authors: McKinley Richard L.
Published: October 2005

Today females are accepting positions in the workforce previously occupied almost exclusively by males. Many of these are located in extreme environments such as high intensity noise. Virtually no information is available about possible interactions of the intense noise exposure with pregnant females. This paper discusses the first in a series of studies designed to provide information about this general situation. The objective of the study was to define the acoustic protection provided to the fetus by the maternal environment of several large laboratory animals. The special instrumentation and methodology employed for the acoustic measurements will be described. Results will include the ambient noise levels found at the fetus during each trimester as well as the amount of sound protection provided by the maternal environments of the large laboratory animals. Logical follow-on research to this effort will be identified during the discussion. [Supported by EPA.]
Susceptibility to noise-induced temporary threshold shift as influenced by the menstrual cycle
Authors: Ahroon W. A. , Davis M. J.
Published: October 2005

There are several published studies demonstrating significant gender differences in susceptibility to noise-induced temporary threshold shifts. Dieroff [Arc. Ohren Nas. Kehlk. 177, 282 (1961)] has noted that women apparently are more resistant to the effects of noise and therefore has advocated that women may be safely assigned to work in noisier environments than may men. Ward [J. Acoust. Soc. Am. 40, 478 (1966)] has noted a frequency by gender interaction and has hypothesized that female observers may have more efficient middle-ear muscles than men providing more protection against low-frequency components of noise but less protection at higher frequencies. There have been several attempts to describe changes in hearing which appear to correlate with the normal or imposed menstrual cycle. The present study applied statistical procedures developed for description of and inferences about time-dependent variables (not used in earlier studies) to an analysis of possible changes in susceptibility to NITTS which correlate with the normal menstrual cycle. The results are discussed in relation to occupational safety and health standards and practical implications of menstrual correlates of changes in auditory perception. [Research supported by NIH.]
TTS growth and frequency spread to a 500 Hz octave band of noise
Authors: Nielsen D. W. , Franseen L. , Fowler D.
Published: October 2005

Six squirrel monkeys were exposed to an octave band of noise centered at 500 Hz and presented at 95 dB SPL for up to 96 hours. TTS4.5 was measured either during a 5-min interruption in the exposure or at the end of continuous exposures of various lengths. Growth of TTS4.5 measured under interrupted and continuous exposures showed no differences. After 16 hours, both growth functions showed plateaus which were followed by a continuation of the growth of TTS4.5 through 96 hours of exposure. As with our previous reports of TTS in this primate, no asymptotic threshold shift was observed. Spread of frequency effects were measured to 24 hour exposures to the same noise. TTS4.5 showed a broad shift of about 14 dB in the 125 Hz–1.5 kHz range. Second TTS4.5 maxima of 10 dB were measured at 4.5 and 7.5 kHz. While the squirrel monkey growth functions parallel published human data, the frequency spread data appears to show a broader primary effect in the low frequencies for the squirrel monkey. [This study was supported in part by Henry Ford Hospital Institutional Grant from the Ford Foundation, The Deafness Research Foundation, and an NIH Biomedical Research Grant.]
Ambient sound level and recovery from TTS: Conflicting results
Authors: Hétu R. , Laliberté L. , Filion J. , St-Cyr J.
Published: October 2005

Recovery rate from TTS was measured under four broadband noise conditions (50, 60, 70, and 80 dBA) in two experiments, each employing 12 subjects. In the first experiment, 13 dB of TTS2 was produced and recovery was measured at TTS15, TTS30, and TTS60. All stimuli were presented through earphones. In the second experiment, 26 dB of TTS2 was produced and recovery was monitored during 120 mn. All noise signals were presented through two loudspeakers. Results from the first experiment showed that the 50 dBA ambient noise level induced significantly faster recovery than the three louder conditions. However, results from the second experiment failed to replicate this finding. The 80 dBA ambiant noise delayed recovery during the first 60 mn and produced a reacquisition of TTS thereafter. No differences were observed for the three other noise levels. These conflicting results are discussed in terms of original TTS2 levels and the method of presenting the noise.
Mechanical impact noise generator for hearing loss studies
Authors: Akay Adnan , Cook Reginald O. , Hamm Charles W.
Published: October 2005

Difficulties in accurate reproduction of impact sounds imposed by dynamic range and phase limitations of conventional audio equipment has greatly impeded laboratory studies of hearing damage from these widely distributed noise sources. In order to simulate exposure to impactive noise existing in industrial situations, various impact noise generation mechanisms were investigated analytically and experimentally to determine the significant characteristics of the radiated sound pulses, including rise time, frequency content, energy level, peak pressure level, repetition rate, etc. Finally, based on these findings, a prototype impact sound generator was designed for use in laboratory noise exposure studies. The motive source chosen for this generator was a large solenoid. The solenoid and the driving mechanism is actuated by a specially designed electronic circuit to control impact duration and repetition rate. Interchangeable “impact heads” differing in geometric configuration and material properties were designed to vary rise time, frequency content, and peak pressure level parameters. [Work done at NIEHS.]
Validation of computerized audiometric testing system for industrial populations
Authors: Thomas W. G. , Finley C. C.
Published: October 2005

Since specific audiometric tests used to evaluate hearing have been standardized and narrowly defined in terms of instrumentation, test stimuli and mechanics of administration, the application of computer technology should be ideally suited to the task of performing the basic pure tone audiometric tests and evaluating changes that may occur in industrial hearing conservation programs. This report describes the development and validation of a Computerized Audiometric Testing System (CATS) capable of testing up to six stations simultaneously. The system uses state-of-the-art electronic design coupled with advanced programming for stimulus control, data analysis, and validation of responses. A total of 55 subjects were used in the validation study—35 in the single-station experiment and 20 in the multiple-station experiment. ALL subjects were alternately tested by manual audiometry and by the CAT system, with the order of testing counter-balanced. The largest mean difference between the two systems in the single-station experiment was 3.7 dB which occurred at 500 Hz in the right ear. Mean differences at all other frequencies were 2.0 dB or less. Analysis of data from both experiments and coefficient of correlation will be described.
A strategy for the interpretation of durational cues in spoken sentences
Authors: Klatt Dennis H.
Published: October 2005

A perceptual strategy will be proposed for interpreting durational cues to (1) the identity of segments, (2) the stress pattern, and (3) aspects of the syntactic structure of spoken utterance. Since segmental durations are influenced by many factors, knowledge of the appropriate rules concerning the phonological and durational patterns of words and word sequences must be precompiled into a decoding network of expected segmental durations. During the processing of an unknown utterance, some deviations from durational expectations provide cues to syntactic structure, while other discrepancies are used to penalize the matching score for a word. For example, if a content word has a longer-than-usual final syllable (including both the vocal and any postvocalic consonants) in English, the end of a constituent phrase or clause is suggested. On the other hand, shorter-than-usual content words are likely to function as the first elements of compounds. [Research supported by the National Institutes of Health.]
A maximum likelihood ratio alternative to the multiple coherence statistic
Authors: Becker Donald W.
Published: October 2005

The multiple coherence function has been suggested for application in multiple receiver detection of common narrowband acoustic signals. As an alternative the maximum likelihood ratio detection statistic is developed for multiple receiver detection of narrowband Gaussian signals in additive white Gaussian noise. For the assumptions of rectangular signal spectrums and sufficiently general nonlinear or random time varying propagation channel models, the maximum likelihood ratio statistic is shown to be equivalent |Σ|/Πtσij where Σ = [σij] is the cross-power spectral density matrix estimate within the signal spectral band. A Monte-Carlo computer simulation procedure is discussed. Receiver Operating Characteristic (ROC) curves resulting from the simulation are presented which suggest that in general the maximum likelihood ratio statistic is superior in detection capability to the multiple coherence statistic.
A technique for automatically aiming an array microphone at the source of direct sound
Authors: Coker C. H. , Christensen S. W.
Published: October 2005

Automatic steering of an array transducer to track the source of sound requires a method for determining the relative phases of direct-path signals of different microphones. Cross correlation has often been suggested for this purpose. But in fact, since reverberations also are correlated with the direct sound, cross correlation is useful only when the direct sound is relatively strong to begin with. We propose a modification to the correlation technique in which the signals, before correlation, are preprocessed to enhance the effect of direct sound relative to reverberations. For this purpose, we suggest the class of nonlinear processes with memory—specifically those with highly asymmetrical impulse responses. We describe in particular a simple circuit that produces a pulse as its output, and responds only to increases in signal energy that were specifically preceeded by intervals with no increase in energy. Correlations of such signals exhibit very sharp peaks, and are dominated by the direct sound, even in presence of strong echos. Since the outputs are logic levels, the correlation can frequently be replaced by simple digital logic.
New fidelity criteria and encoding strategies for acoustic data compression
Authors: Rickard J. T. , Kolesar R. R.
Published: October 2005

A study of fidelity criteria (i.e., distortion measures) appropriate for data compression of passive sonar signals was conducted. The classical mean squared error (MSE) criterion was found to be a poor choice for this application, as well as other applications wherein the source signal is to be spectrum analyzed. Two new fidelity criteria, the mean incoherence (MIC) and mean log-coherence (MLC), were developed and tested on passive sonar type signals. The experimental results indicated that these criteria provide an accurate assessment of the distortion produced by a data compression system on this type of signal. The rate-distortion functions of a Gaussian source signal, subject either to MIC or MLC fidelity requirements, were then derived. These functions specify the minimum transmission rate (e.g., bits/sample) required in order to reproduce the source signal with a given distortion. Also, the analysis indicates the effect of optimum encoding on the source signal power spectrum. A number of near-optimum encoding schemes were then developed for these new fidelity criteria. [Work supported by Naval Ocean Systems Center.]
Digital filter design considerations for sonar trainer noise generation
Authors: Schmid C. E.
Published: October 2005

Digital filters were designed and built to realistically simulate background noise for a submarine sonar operational training system. Broadband spectral models of rain and distant shipping were implemented using shift register noise generators followed by digital filters. Marine-life noise was reconstructed by playing actual tape recordings through a digital filter which accounted for propagation characteristics. Decimators and interpolators were used to alter sample rates for the various sonar channels. Spatial effects of noise were dynamically controlled with inverse beamformers. The effect of word size, bias, aliasing, and spatial control will be discussed. Also, audio examples of the simulated background noise will be presented. [Work supported by NUSC, New London.]
Signal transmission—the view from k-space
Authors: Lauer R. B. , Jensen E. P.
Published: October 2005

The wavenumber (k) domain representation of signal transmission offers many advantages over the conventional propagation loss versus range representation. These include separation of propagation path types such as RSR, BB, and surface duct into different wavenumber regions. Since results in k-space are easily interpretable in terms of ray paths, this representation can be used to compare ray and field theory results to determine the manner in which ray theory breaks down with decreasing frequency. Selected field theory results are given for various contrived environments so as to relate variations of acoustic and environmental parameters to acoustic pressure variations as observed in k-space. The variations are over frequency, depths of source, receiver and ocean bottom, bottom loss, and sound speed profile. Analogous results from ray theory are presented and compared to the field theory results. The k-space domain representation is shown to provide the means for defining the terms narrowband and broadband including a transition between them. [Work supported by NUSC.]
Digital acoustic data recording system
Authors: Holmes H. K. , Baines E. F.
Published: October 2005

Perhaps the weakest link in the acoustic measurement chain has been the analog tape recorder with its limited dynamic range being the most critical parameter. One method for circumventing this problem is to digitize the signal, with a suitable dynamic range system, and record the signal in digital form. An additional requirement imposed on the system is that the reproduced signal should be of a very high audible quality such that recordings obtained might be useful in subjective response to noise experiments. Though many techniques are being implemented to accomplish these ends, e.g., nonbinary bit weighting and multichannel parallel record formats; the approach described here has multiple data channels, binarily weighted and recorded serially on a single tape track. This approach has a linear quantization interval and is not sensitive to tape skew conditions; however, a higher bit rate must be accommodated. A system has been developed which accommodates four channels each having a dc to 20 kHz frequency response and a dynamic range in excess of 75 dB. This information along with time code and voice annotation is recorded on an inexpensive video tape recorder.
Measurement of directivity factor of small sound sources in reverberation rooms
Authors: Walker Bruce E.
Published: October 2005

The directivity factor of small sound sources in the direction of the measurement microphone may be determined in a reverberant room by using a pressure gradient microphone to separate the direct and reverberant components of the sound field. Experimental verification of the theory, together with analysis of the advantages and limitations of the method compared to more conventional means will be presented.
Directive spectrum analyzing system by use of revolving microphone
Authors: Abe M. , Ishigame M. , Kido K.
Published: October 2005

This paper proposes a directive spectrum analyzing system using two microphones, one of which is fixed with the other revolving around the fixed one. The directivity pattern of the system can be arbitrarily changed by adjusting the delay time given to the microphones. A unibeam directivity is achieved when the outputs of the microphones are shifted so that both outputs are in phase for the incident sound from the specified direction. After giving the adequate delay time, the mean power spectrum and the mean cross power spectrum are computed during a full turn of the revolving microphone, and the power spectrum of the incident sound from the specified direction is estimated. The longer the distance between two microphones, the sharper the directivity is. This system is applicable to the case of many sound sources and is effective not only for the noise source detection in the noise control engineering but also for the underwater passive sonars.
Effect of the shape of time window in estimating the transfer characteristics of the acoustic system having group delay or reverberation
Authors: Takebayashi Y. , Kido K.
Published: October 2005

This paper describes the effect of the shape of the time window on the errors in estimating the coherence function and the transfer function of the system having group delay or reverberation. It is well known that the windowing determines the spectral resolution and the sidelobes, and the proper time window should be selected from the point of view. The windowing has another effect when the system has group delay. Because the cross-power spectrum obtained from DFTs is equivalent to the circular convolution of the input and the output sequences and the signals come to contain the uncorrelated components in the initial and the final parts of the windows due to group delay, the estimation of the coherence function is biased towards zero. The estimation is improved by using the Hanning window if the delay is sufficiently shorter than the window duration, but the rectangular window is superior to the Hanning window if the delay is longer than about 0.18 times the window duration. The analytical and the experimental results are presented numerically. For the system having reverberation, a similar discussion is also given.
Binaural dissimilarity: Its importance and realization in room-acoustical design
Authors: Schroeder M. R. , Gottlob D. , Eysholdt U.
Published: October 2005

In numerous subjective evaluations of room responses, the importance of “binaural dissimilarity” for listener preference has been established. (Binaural dissimilarity is a measure of how different the two ear signals are; it is strongly enhanced by lateral reflections.) The subjective evaluations are based both on real halls [M. R. Schroeder, D. Gottlob, and K. F. Siebrasse, “Comparative Study of European Concert Halls,” J. Acoust. Soc. Am. 56, 1195–1201 (1974)], on digitally modified impulse responses of real halls [M. R. Schroeder, “Computer Models for Concert Hall Acoustics,” Am. J. Phys. 41, 461–471 (1973); U. Eysholdt and D. Gottlob, “Digital Synthesis of Sound Fields: A New Method to Study the Influence of Single Acoustical Parameters on Preference Judgements,” Proc. 9th Int. Congr. Acoust., Madrid (1977) p.4] and on simulated sound fields [Y. Ando, “Subjective Preference Tests of Simulated Sound Fields for Optimum Design of Concert Halls,” J. Acoust. Soc. Am. 63, 1, S85 (A) (1978)]. In this paper we review the subjective results and discuss their implications for room-acoustical design.
Influence of room shape on subjective preference in multipurpose auditorium
Authors: Sekiguchi K. , Kimura S.
Published: October 2005

We evaluated the subjective quantity of reverberation, quality of reverberation preference and as such by performing hearing tests of music through sound reproduction of a dummy head recording in actual 13 auditoriums after which we examined the design of room shape. As we found subjective quantity of sound chiefly consisted of the factor of loudness and quantity of reverberation. Preference and quantity of reverberation were also found to be correlated with these two factor axies. Subjective differences between the quantity of reverberation is closely correlated with criterion of initial sound decay rate; definition (D); early decay time (EDT); center time (Ts). Preference was proved to be correlated with room shape characteristics value in which we found integration value from spacial angles of ceiling and walls multified by sound absorption and the energy addition value of direct sound and reflected sound within two times. Only from the figures in the planning stage, it might be inferred with some allowances that we could make an estimate of the subjective quantities of preference.
Speech intelligibility in real and simulated sound fields
Authors: Kleiner M.
Published: October 2005

The possibility of simulating the sound fields in a theater by electroacoustic means has been investigated using speech intelligibility tests. The sound field simulations have been based on two different concepts. The first simulation experiment used geometrical and statistical acoustics. Corrections were introduced to account for speaker directivity, propagation over the audience, and other factors. The results show that it is hard to simulate the properties using calculated data. This applies especially to an auditorium with a complex wall structure such as the theater tested. There was no correlation with the speech intelligibility results obtained by direct listening in the theater. The second simulation experiment used impulse response data measured in the theater. The simulations were based on the total incident energy and the directions could only be approximated. In this case the correlation between results obtained using direct listening and listening to the simulated sound fields was as high as between results obtained using direct listening and listening to dummy head recordings made in the theater.
Improved ambience at the Capitol Theatre
Authors: Richards Roy L. , Chaudiere Herbert T.
Published: October 2005

The Capitol Theatre in Yakima, Washington, is an opulent and luxurious representation of the theatres constructed early in this century for the great Pantages Vaudeville Circuit. In 1975 a tragic fire gutted the theatre, and central Washington lost its only major performing arts facility. The theatre's structure survived the fire, however, and a concerned public has raised the funds required :for full restoration. While the original theatre may have been a model showcase for its day, the acoustics were something less than optimum by contemporary standards. In particular, a large, high dome just outside the 36-ft prosecenium, and over one-half the main floor seating under a huge first balcony, left many seats with weak, dry sound. Because architectural solutions were inconsistent with an accurate restoration, electro-acoustical methods were employed. A distributed sound reinforcement system has been designed to provide “early reflections” for all seating areas and selectable amounts of added reverberance. System design features will be described in this paper, as well as other theatre acoustical characteristics. Since the theatre is scheduled to open 2 November, a report on the actual performance of the system will hopefully be made when this paper is delivered.
Analytic expansion technique for ambient noise directionality determination
Authors: Yen N.
Published: October 2005

A new technique, derived from the formation of the noise field, has been developed to determine ambient noise directionality from its spatial coherence property according to the output of a line array. The underlying concept of this approach of ambient noise directionality determination is based on the assumption that the noise field is attributed from many plane waves. An algorithm utilized the Prony's method has been implemented for computing the dominant plane waves intensity and their corresponding directions and representing the noise spatial coherence in an expression of analytic function. In contrast to the conventional beam-forming used in noise directionality measurement, the result obtained from this new technique is not limited in angular resolution due to finite aperture size of the array. A simulated noise field and noise data from ocean environment have been used as examples to illustrate the features of this computing algorithm in the determination of the noise directionality. [Work supported by NAVSEA.]
Array optimization via subarrays
Authors: Streit Roy L.
Published: October 2005

Let the (x,y,z) coordinates of a discrete antenna array be given. No special geometry is assumed. Specify a design frequency. PROBLEM: Compute element excitations for which directivity index (DI) is maximized. In principle, this problem is easily solved by finding the largest eigenvalue and corresponding eigenvector of a certain matrix. In practice, this procedure is handicapped by excessive computer memory requirements. For example, a 300 element array requires at least 180,000 storage locations. This paper shows that a numerical method known as group coordinate relaxation (GCR) can maximize DI on computers with only modest memory. It can be tailored to the computer memory available. The technique trades off memory for computational speed: the more memory available, the faster DI is maximized. Conceptually, the GCR method breaks the full array into distinct subarrays of manageable size. Working with the first subarray, it computes new excitations for that subarray so that the DI of the full array is increased. Cycling through the subarrays in turn until the DI of the full array cannot be further increased is the essence of GCR. It is proved convergent for general antennas.
Equivalence of cross-line multiplicative arrays and filled-in area arrays for noise measurement and detection purposes
Authors: Berkman E. F. , Nitsche J. R.
Published: October 2005

To aid in early design it is sometimes desired to estimate the self-noise of a planar array without the investment of actually constructing such an array. For rectangular separable shaded planar arrays in a spatially homogeneous noise field, it can be shown that the self-noise of a planar array with aperture L1 × L2 is identical to the noise response of a multiplicatively processed pair of crossed line arrays with apertures 2L and 2L2 and appropriately shaded. Thus, the number of elements for test purposes is considerably reduced (from N2 to 4N for a square array). For this equivalency, the appropriate line m-ray shading functions are the auto-correlation functions of the row and column shading functions of the filled-in planar array. Detection performance of crossed-line multiplicatively processed arrays with beampattern equivalent to filled-in planar arrays is also discussed.
Synthesis of the diffraction fields of acoustic echo-sounding antennas
Authors: Adekola S. Adeniyi
Published: October 2005

Based on a more general integral formulation developed for the acoustic echo-sounding antenna pattern [S. A. Adekola, J. Acoust. Soc. Am. 60, 230–239 (1976)], this paper deals with the pattern-synthesis-by employing a pair of Hankel-Transform integrals that uses the acoustic farfield pattern variable kasinθ for a circular antenna source. As a numerical example, we synthesize a given sin(u)/u pattern for a symmetric aperture excitation using Johnk's general Synthesis method [C. H. Walter, Traveling Wave Antennas (Dover, New York, 1970), pp. 56–63]. A series expression resulting from the aperture excitation is then developed for the approximate pattern Qap(u). By considering three and seven terms from the series expression derived for the approximate pattern, the corresponding source distributions are also calculated. A comparison of the approximate synthesized pattern with the exact pattern shows good agreement. For example, the 3-dB beamwidth of 6.82° obtained from the synthesized pattern at 1 kHz carrier-frequency is the same order of magnitude as 7.96° for the exact pattern at the same carrier frequency. Also, first sidelobe-level of the exact pattern is 13.26 dB compared with 14.32 dB and 14.43 dB for the seven- and three-term pattern approximations, respectively. Error analysis reveals that the maximum percentage-error between the exact and synthesized patterns is 8.42%. One concludes from the source excitations obtained, that the addition of more terms increases the intensity of the source-distributions at the aperture-edge, and eventually gives the singularity of the Hankel-Transform of the sin(u)/u pattern in the limit.
Sleep interference from low-level sounds
Authors: Horonjeff R. D. , Fidell S. A. , Bennett R. L. , Teffeteller S. R.
Published: October 2005

Fourteen participants provided behavioral awakening responses to long and short duration sounds in their own bedrooms over a three-week period. Four sound sources were presented in two temporal patterns (10-dB-down durations of 10 s and 16 min) in an adaptive design that maximized data acquisition at lower sound levels and probabilities of awakening. The results suggested that (1) the normalized probability of awakening was a linear function of the maximum sound level for a given temporal presentation pattern, (2) the temporal pattern of exposure had a major effect on sleep interference that may be reconciled on the basis of equal energy for equal probability of awakening, and (3) not all sounds of equal A-level produce equal probabilities of awakening.
Sleep interference: A need for reevaluation
Authors: Bragdon Clifford R.
Published: October 2005

Environmental noise has been identified as a factor affecting the quality, duration, and recuperative value of sleep. Several community noise studies have suggested sleep interference is a significant environmental impact. Based upon research conducted in San Juan, Puerto Rico, and Atlanta, Georgia, the problem of sleep interference may be underestimated. At least three factors should be reevaluated. The first is the diurnal assumption concerning the sleep cycle. A large population by virtue of age, health condition, and employment have daytime sleeping habits. Secondly, the impact on the receiver during the sleep state may actually be greater due to changing energy systems for residences which use natural ventilation, increase the interior noise level. Lastly, there is evidence that the population in high noise impact areas may be using significant amount of over-the-counter sleeping preparations which in the long term may not be beneficial. The role of environmental noise upon sleep although complex needs further examination to adequately document the extent of impact in order to provide necessary solutions.
The effects of stimulus characteristics, context, and personality factors on human response to aircraft noise
Authors: Gunn W. J. , Shigehisa T. , Shepherd W. T.
Published: October 2005

Current aircraft noise certification procedures are based upon psychophysical data derived from laboratory experiments in which test subjects responded to meaningless sounds (bands of noise) in an unrealistic sterile laboratory environment, while they were engaged in none of the normal activities which are typically interrupted by aircraft overflights. Over the past eight years, the authors have conducted a systematic study of the effects of stimulus characteristics (directionality, level and spectrum), contextual effects (activities engaged in during aircraft noise exposure and varying room illumination levels) and personality type of the test subjects. The results of the series of experiments show that all of these factors significantly effect human response to aircraft noise and suggest the need for more realistic research in order to improve noise certification procedures.
Human response to audible noise from high-voltage transmission lines
Authors: Molino J. A. , Zerdy G. A. , Lerner N. D.
Published: October 2005

The aversiveness of audible (corona) noise produced by extra-high voltage (EHV) overhead transmission lines during moist weather was assessed. Samples of corona noise from two lines, other common environmental noises, and artifical reference stimuli were compared using a behavioral preference procedure. Corona noise samples were found to be equally preferred to (1) a 1000-Hz octave band of white noise approximately 12 dB SPL higher than the corona noises and (2) a collection of other environmental noises approximately 9 dB SPL higher than the corona noises. Corona noise was significantly less preferred than the ambient noises occurring near the transmission lines. One sample of corona noise was comparable in aversiveness to a sample of room air conditioner noise; the other sample of corona noise was somewhat more aversive. While all of the commonly used frequency weighting scales correlated strongly with preference, D-weighted sound level provided the highest correlation with the preference data and the smallest standard error bands. [Sponsored by the Department of Energy.]
Interpretation of acoustic target properties from computed and measured reflection behavior
Authors: Dragonette Louis R. , Neubauer Werner G.
Published: October 2005

Measurements of the form function of spheres and cylinders have been made in the air and water acoustic facilities at NRL. The accuracy of these experiments is within two percent of exact normal mode series computations. The results demonstrate the feasibility of obtaining accurate, quantitative evaluations of the scattering from arbitrarily shaped elastic targets experimentaUy. For elastic spheres and cylinders the reflection function (form function vs ka) is marked by a series of irregularly spaced variations, which are related to free body vibrations of the target. Theoretical investigations have demonstrated that families of resonances are related to circumferential waves, and this relationship is used to predict the occurrence of the Rayleigh circumferential wave at low ka. The Rayleigh wave is observed experimentally in the low ka region. Nulls in the form function caused by the presence of the Rayleigh wave are used to examine target properties. Scattering by hollow shells is described in terms of contributing mechanisms such as circumferential waves. For thin shells circumferential waves are related to Lamb waves on flat plates.
Dynamics of acoustic resonance scattering from spherical targets: Application to gas bubbles in fluids
Authors: Farhan Ameenah R. , George J. , Mezzorani G. , Nagl A. , Sage K. A. , Überall H.
Published: October 2005

In this study, we investigate the dynamics of surface motion of a penetrable spherical body subjected to an incident plane acoustic wave. The results should be valid for objects of rather general internal consistency since they are based on quite basic physical considerations, but they are illustrated here by the example of a gas bubble in a fluid. It is shown that surface waves generated in the scattering process circumnavigate the target sphere and, by a process of in-phase “resonant reinforcement,” excite its multipole resonances at those eigenfrequencies at which n + 12 wavelengths (n being an integer) span the circumference. Phase matching is achieved here due to the fact that the surface wave suffers a phase jump of π/2 at each of the two “caustic points” on the sphere at which the surface waves converge. Surface motions and circumferential waves on the bubble are graphically demonstrated, both on and off resonance. This work was supported by the Office of Marine Technology, Engineering Development Laboratory, NOAA, and by the Office of Naval Research, Code 421.]
A method of measuring sound power levels of vehicles using a reverberant field in tunnel
Authors: Tachibana H. , Ishii K.
Published: October 2005

For the measurement of sound power levels of freely running vehicles, a new method using a reverberant field in a tunnel and a reference sound source was tested. In this test, a microphone was set on the wall at the center of the testing area (121 m, in this case) in a straight tunnel that is 1 km in length, and sounds generated by freely running vehicles were recorded on a tape recorder for each period within which they were in the testing area. The tape recordings were replayed through 1-octave bandpass filters (63 ∼ 4 kHz) onto a square integrator. Then, comparing these integrated values with the value for the reference sound source that had been measured previously in much the same way as mentioned above, and with consideration of the differences in the integration times, 1-octave band power levels for each vehicle were obtained. With these values, A-weighted power levels were calculated. By this method, the sound power levels of 133 passenger cars and 141 trucks were measured.
Giant monopole resonances in the scattering of viscoelastic waves from gas-filled spherical cavities in solids, and of acoustic waves from bubbles in liquids
Authors: Gaunaurd G. C. , Scharnhorst K. P. , Überall H.
Published: October 2005

Our previous resonance formalism for the scattering of p-waves by fluid-filled cavities in solids [J. Acoust. Soc. Am. 63, S40(A) (1978) and J. Acoust. Soc. Am. 63, 1690 (1978)] is extended by performing the theoretical analysis needed for the complete study of the monopole mode of vibration. We develop a complete analysis of the giant fundamental resonance and its overtones in the monopole case. We particularize our results to the Rayleigh region, and to the cases of evacuated cavities in robber and to gas bubbles in water, recovering and extending some results available in the literature. We have quantitatively studied how absorption shifts the resonance peaks and broadens their width. The width of the resonance peaks is found to be linearly dependent on the resonance frequencies and this important result is used to determine the shear absorption parameter of rubbers. The giant monopole resonance for air-filled cavities in rubber is shown to contain a contribution from the shear waves in the cavity-wall and another from the resonance oscillations of the air-filling in a 15:1 ratio, for this material combination. Numerous plots are displayed including those of the summed amplitudes fpp and fps accounting for 20 multipole contributions, and the dominance of the monopole term emerges clearly from this result. [H. Ü. is also at Catholic U. and was partially supported by ONR, Code 421.]
Redirective scattering cross section reduction of a cylinder: A mathematical model
Authors: Belle D. M. , Sullivan E. J.
Published: October 2005

To study the modification of the scattering cross section of cylinders by periodic or aperiodic surface loading we consider scattering by a cylinder with non-uniform boundary conditions. Exact analytical approaches lead to considerable complexity. This paper explores the use of a least squares boundary residual method [J. Brian Davies, IEEE Trans. Microwave Theory Tech. MTT-21(2), 99–103 (1973)] to obtain the reradiated field or scattering pattern of a cylinder clad by an alternating sequence of axially directed acoustically hard and soft strips, under uniform plane wave illumination. Data will be presented with the cylinder diameter, a, the number of strips, M, the strip widths, aφn, and the relative weighting of the soft and hard boundary conditions, H, as parameters. We considered two strip cylinders with 9 ⩽ ka ⩽ 30, and a sequence of results for ka = 5, 10, 20, and 30 with 2, 4, 8, 16, and 18 strips. Single precision programming sensibly limited the number of terms, N, in our Hankel function expansion to 18 thus fluctuations on the boundary modeled by (cossin) Nφ cannot be resolved if they exceed this periodicity. Results agreed well with classical results for the hard and soft cylinder for ka = 5, 10, and with experimental results available for a slotted cylinder at ka = 5. Single precision limited us to values of 2a ≲ 9.5λ.
Acoustic biasing of CM and N1 responses to high-frequency tone pips
Authors: Strelioff D. , Kroin J. , Himelfarb M.
Published: October 2005

The effect of basilar membrane (BM) displacement and associated endocochlear potential (EP) change produced by a 50-Hz, 80–110-dB SPL tone (modulator) upon the cochlear microphonic (CM) and whole nerve (N1) responses to high frequency tone pips was studied in the guinea pig. CM responses to low level 3.1 kHz tone pips and the EP variation produced by the modulator were recorded with a scala media electrode in the first turn. A round window electrode recorded N1 responses. CM and N1 amplitudes were measured as a function of the timing of the tone pip during the cycle of the modulator. The CM amplitude, which was proportional to EP change for modulator levels below 95 dB SPL and reduced except near the zero crossings of EP change for higher levels, is consistant with a model having a saturating nonlinearity in the transfer curve between the CM and acoustic waveforms. In contrast, the N1 amplitude was reduced everywhere and at all modulation levels, reduction being least near both zero crossing. [Work supported by the Deafness Research Foundation.]
Finite element solution of a two-dimensional cochlear model
Authors: Janssen M. J. A. , Segal A. , Viergever M. A.
Published: October 2005

A two-dimensional model of the cochlea is solved by direct application of a numerical procedure, the finite element method, to the basic equations. The finite element method is more suitable than e.g. the method of finite differences [S. T. Neely, Thesis (California Inst. of Technology, Pasadena, 1977)] because a local refinement of the grid is easily accomplished. This local refinement reduces the amount of computing time considerably. The program makes use of a standard package called AFEP, which has been developed at the Dept. of Mathematics in Delft; it has been tested on many problems and proven to be reliable. For the problem under consideration one run requires about 10 seconds on an IBM 370/158 computer, while the accuracy of the results is much larger than of any other results obtained so far.
Characterization of a nonlinear cochlear model by wideband stimuli
Authors: Hall J. L.
Published: October 2005

The use of wide-band stimuli to determine the frequency selectivity of the peripheral auditory system (de Boer and Kuyper's “reverse correlation”) raises the following questions: (1) In view of nonlinear interactions among components of a complex stimulus (two-tone suppression), is it meaningful to relate frequency selectivity determined by wide-band stimuli to results from pure-tone stimulation? (2) In relating stimulus intensity for tones and for wide-band stimuli at which nonlinear decrease of frequency selectivity occurs, over what bandwidth should noise power be measured? We measured the frequency selectivity of a nonlinear cochlear model with pure tones and with wide-band stimuli. In both cases the frequency selectivity decreases at high stimulus intensities, and the shapes of the resulting response curves are similar. In agreement with the earlier result that the signal controling the nonlinearity is less sharply tuned than the neural excitatory signal (J. Acoust. Soc. Am. 61, 520–524 (1977)), we find that for equivalent reduction of frequency selectivity by tones and by noise of equal power the noise power must be integrated over several critical bands. As a separate result, we suggest modifications of the reverse correlation procedure that may decrease the random variability of experimental results.
The plateaus in basilar membrane vibration data—explained
Authors: Viergever M. A.
Published: October 2005

In recent measurements of basilar membrane tuning curves both the amplitude and the phase approach a constant value for frequencies above the transition frequency. To analyse the origin of these plateaus it is common to use the property that the basilar membrane-stapes displacement ratio has the same form when plotted against x (=distance to stapes) or log f (=log frequency). An analysis of the situation beyond the characteristic place then shows that the phase plateau is caused by the mass-controlled character of the membrane impedance there. The magnitude of the ratio decreases sharply in that region; the added mass effect of multi-dimensional modelling leads to a change in slope, but not to a plateau. The x vs log f transformation however looses its validity for frequencies above the highest resonance frequency in the cochlea. For those frequencies the membrane response tends to become frequency independent, which yields the plateau. Hence amplitude plateaus measured in one animal at different places must begin at the same frequency, and must have a decreasing level with increasing x. This is in agreement with the experimental data.
Temporal aspects of responses of auditory-nerve fibers to steady-state vowels
Authors: Young E. D. , Sachs M. B.
Published: October 2005

To explore the manner in which features of the spectra of multi-component stimuli are encoded in the discharge patterns of auditory-nerve fibers, responses to steady-state synthetic vowels (/a/, /ε/, /u/, and /I/) were recorded. Between 120 and 260 fibers were studied in each cat and the population response was estimated by recording the response of all the fibers to the same vowel at a number of stimulus levels. Examination of plots of average discharge rate versus characteristic frequency revealed evidence for “place” representation of the vowels' formant frequencies only at lower sound levels and only for vowels with widely spaced formant frequencies [Sachs and Young, J. Acoust. Soc. Am. 63, S76 (1978)]. In this paper, we present data on the periodicity of responses of auditory-nerve fibers to synthetic vowels. The temporal structure of the responses as seen in period histograms is largely dominated by the fundamental component of the vowel and the components at the formant frequencies. Each of these components dominates the responses of fibers whose characteristic frequencies are near the component frequency. In vowels with widely spaced formant frequencies, some domination by intermediate frequency components is observed. At high sound levels, phase-locking to the first formant spreads and phase-locking to other components is reduced. [Supported by NIH Grant No. NS12524.]