bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation of flexural waves on a fluid-loaded plate with many identical supports
Authors: Smith P. W. , Berkman E. F.
Published: October 2005

A power-balance analysis is carried out for the response and sound radiation of a homogeneous fluid-loaded wave-bearing structure with many identical supports, when the structure is driven at one support point. A single second-order difference equation is found for the response, subject to the hypothesis that the energy flux from any support to its neighbors involves only one wave type. Results have been calculated for a thin steel plate with inertial supports and water on one side, for frequencies less than the critical frequency. A marked difference is found between the levels of energy flux away from and toward the source in the same bay (i.e., reverberation is not strong). The attenuation rate due solely to sound radiation is significant (1–2 dB per support) except at low frequencies. Internal dissipation is enhanced by the reverberation, relative to dissipation in a plate without supports.
Analysis of vibration transmission in engine structures
Authors: DeJong R. G. , Manning J. E.
Published: October 2005

The vibration transmission in engine structures was studied, combining the theoretical approach formulated by Statistical Energy Analysis (SEA) and the experimental measurements of mechanical mobility (inverse of impedance) and damping. An analytical model of the energy flow between different engine components was used to identify means of changing the dynamic characteristics of various components and covers in order to reduce the vibration level and thereby reduce the radiated noise. Approximations were made to the SEA equations for the vibrational energy transfer between coupled structures in order to relate the coupling factors in the analytical model to experimentally measurable point mobilities. Mobility and damping measurements were made on three truck diesel engines. The component vibration levels predicted by the analytic model were compared with those measured when the engines were operating and generally good agreement was found. The model was then used to identify means of reducing the component vibration levels through improving the isolation and/or damping of the components. [Work supported by DOT Contract No. DOT-TSC-1013.]
Frequency response of the eardrums of some submammalian vertebrates
Authors: Moffat Anne J. M. , Capranica Robert R.
Published: October 2005

A laser light scattering interferometer was used to measure the amplitudes of sound induced vibrations of the tympana of two amphibian (Bufo americanus and Hyla cinerea) and one reptilian (Chrysemys scripta elegans) species. The maximum amplitude varied somewhat across species but was on the order of several hundred Ångstroms for a stimulus intensity of 90 dB SPL. In Bufo americanus the vibration amplitude is fairly constant to about 1.75 kHz then decreases at a rate of 21 dB/octave whereas in Hyla cinerea the roll off begins above 2.5 kHz and has a slope of between 14 and 22 dB/octave. In Chrysemys scripta elegans the vibration amplitude increases up to 500 Hz, drops off slowly (6.5–11 dB/octave) between 650 and 1250 Hz then more steeply (8.5–15 dB/octave) above 1250 Hz. In each species the frequency at which the vibration amplitude starts to decrease is correlated with the highest best excitatory frequency found in eighth nerve fibers, suggesting that the upper frequency of hearing is limited by the middle ear. In the amphibian species the displacement of the center of the tympanum, where the extracolumella attaches, is less than that of the free membrane area surrounding it suggesting that this free membrane acts as a conical level and contributes to driving the middle ear ossicles. [Work supported by NSF.]
The cochlea of the bat, Pteronotus p. parnellii
Authors: Henson M. M. , Henson O. W. , Jenkins D. B.
Published: October 2005

The highly specialized ear of the bat, Pteronotus parnellii parnellii, has been studied with electrophysiological and anatomical techniques. The cochlea is wide (4.5 mm) and has large round window and perilymphatic duct openings through which many structures can be approached. Within the large basal turn there is marked variation in nerve fiber density and the lining of the scala tympani is greatly thickened. Also in the basal turn the perilymphatic spaces and stria vascularis are enlarged in certain regions. In some parts of the cochlea the spiral ganglion cells are located in the internal auditory meatus rather than in the osseous spiral lamina. The hair cells and supportive cells generally resemble those of other mammals although the first space of Nuel is exceptionally large. These and other features will be depicted in light and scanning and transmission electron micrographs and correlated with physiological records obtained from the cochleae of these bats. [Work supported by USPHS, Grant NS 12445.]
Study of a combined noninvasive-ECochG and BSER recording technique
Authors: Durrant J. D.
Published: October 2005

A new electrode was developed for recording the electrocochleogram (ECochG) from the ear canal. The electrode has a self-retaining assembly, is placed without the aid of an otoscope, requires no anesthesia, and can be used under an earphone. The electrode, per se, is of the surface type and is placed on the floor of the ear canal about 12-cm from the eardrum. The focus of this report is on observations carried out in normal hearing subjects in which the ear canal recording was referenced to an electrode located on the forehead at hairline (which for purposes of recording the brainstem responses is not much different from the vertex). The interest in this configuration was in examining the potential for, in effect, combining the ECochG and the BSER (brainstem evoked response) in a single recording. This technique has been found to provide fairly reliable brainstem responses, however, with an appreciable facilitation of the eighth nerve response (N1 or wave I). Unfortunately, the latter has proven to be quite variable, independent of the overall sensitivity of the recording. Possible sources of this problem and the relative limitations versus merits of this recording technique are discussed.
Frequency adaptation in the cochlear nerve of chinchilla
Authors: Hou S. M.
Published: October 2005

The behavior of cochlear nerve responding to high-frequency click-train stimuli was studied by signal averaging technique from chinchilla. The findings support earlier human psychophysical observations, i.e., the adaptation rate of the cochlear nerve is faster at higher stimulus frequencies than at lower ones (⩾2000 Hz). It is also demonstrated that within a long stimulus train (200 ms or longer}, the cochlear nerve exhibits a cyclic neural recovery pattern. The period of this cyclic event is also a function of stimulus frequency. These evidences concur with the current concept of auditory fatigue, however, the magnitudes of adaptation of brain stem evoked component was found to be less sensitive than that from cochlear nerve in the intrastimulus recovery cycle. [Supported in part by an NIH grant and grants to Dr. David M. Lipscomb.]
Auditory temporal modulation transfer function for the goldfish
Authors: Fay R. R.
Published: October 2005

Restrained goldfish were classically conditioned to suppress respiration to an acoustic signal consisting of a seven second period of sinusoidal amplitude modulation impressed upon a continuous wide-band noise. Psychometric functions were constructed by plotting a measure of respiratory suppression as a function of the signal's modulation depth (m). Arbitrarily defined threshold values of m were plotted as a function of modulation frequency between 5 and 600 Hz. This TMTF is essentially flat to about 250 Hz with values of 20 log m falling between −12 and −18. The intensity difference limen is calculated to be about 1 dB(ΔI/I approximately 0.25), and the minimum integration time, although not precisely measured, appears to be less than that for man. This conclusion is consistent with the finding that goldfish show considerably less temporal summation in signal detection than man [A. Popper, J. Acoust. Soc. Am. 52, 596–602 (1972)]. The results suggest that the goldfish auditory system is specially adapted for detecting transient sounds, and for accurately preserving the fine structure (phase information) of auditory signals. [Research supported by the NSF.]
Frequency selectivity in the parakeet: The relation between critical band and psychophysical tuning curves
Authors: Saunders J. C. , Bock G. R.
Published: October 2005

The critical band may be viewed as an indication of the bandwidth of the internal auditory filter. The bandwidth of a filter, as a measure of its frequency selectivity is not easily compared with the bandwidths of other filters. One useful measure of frequency selectivity, however, can be found by dividing the bandwidth of a filter at some arbitrary point below the peak, into the center frequency of the filter. This so called “Q” measure is valuable because it represents a ratio and thus can be compared among filters of different center frequencies. We have assumed that indirect measures of the critical band (the critical ratio) represent the bandwidth of the internal filter at a consistent point below the peak. We have thus calculated a Qcritical ratio for all the available data points in the parakeet. Psychophysical tuning curves (PTC) have been empirically obtained for eight different probe frequencies in the parakeet. A Q10 dB was calculated for each of these tuning curves and compared with the data describing Qcritical ratio, at ten different frequencies. The plot over frequency of Qcritical ratio and Q10 dB of the PTC's, although differing in absolute values, were nearly identical in shape. Frequency selectivity is poor in the low frequencies, raises sharply between 2.5 and 4.0 kHz, and then becomes poor again at higher frequencies. The results will be discussed with regard to the relation between the critical band and psychophysical tuning curves and frequency selectivity in the parakeet. [Work supported by NSF.]
Sound production of humpback whales, Megaptera novaeangliae, in Alaskan waters
Authors: Thompson P. O. , Cummings W. C. , Kennison S. J.
Published: October 2005

Underwater sounds of feeding humpback whales were recorded 90–130 km south of Juneau in August, 1975. Although there were scattered grunts, yelps, moans, and low-frequency narrow-band pulses, as expected, the most pervasive sounds were trains of 25–80 Hz broadband pulses that had a mean repetition rate of 1 per sec. They were superposed on 40ndash;1250-Hz continuous noise which swelled and decayed as pulse trains began and ended, varying in duration from 15 to 100 sec. Incidental sounds made by surfaced animals were shrieks and trumpeting made through the blowholes and wide-band pulses produced by flipper or tail slaps on the water's surface. Also recorded were weaker wide-band pulse trains that were characterized by (1) Lack of energy below 500 Hz, (2) uneven amplitude and repetition interval, and (3) repetition rate of several per sec. The source of these pulses was believed to be clashing of baleen plates from wave action as a whale skimmed food organisms at the surface. Estimated maximum underwater source levels (referred to 1 μ Pa at 1 m) were grunt, 190 dB; trumpeting, 185 dB; tail slap, 183 dB; shriek, 180 dB; and low-frequency broadband pulse, 176 dB.
Relative ease of learning a decibel-type scale versus a sone-type scale
Authors: Molino J. A. , Bevan M. G.
Published: October 2005

One group of subjects was trained to rate the loudness of tape-recorded sounds on a decibel-type scale, while another group learned to rate the same sounds on a sone-type scale. In a pretest, subjects wrote magnitude estimates of 30 sounds. During training, subjects heard 60 sounds, each accompanied by the display of a placard giving the scale value. In the post-test, subjects listened to another 30 sounds and wrote their estimates for the scale values which they had just learned. The 6-sec sound samples were selected from 27 different spectra (both artificial and environmental) and ranged from 60 to 100 dB on the A-weighted scale. They were presented simultaneously over loudspeakers in identical lecture rooms for each group. In the pretest the mean correlation coefficient for the decibel group was 0.72 (26 subjects) while the mean correlation for the sone group was 0.65 (26 subjects). In the post-test the mean correlations were 0.88 and 0.85 for the two groups, respectively. Thus, although a sone-type scale supposedly reflects subjective ratio relationships, it was not easier to learn than a decibel-type scale.
Industrial machinery and workers' compensation claims for hearing loss
Authors: Hershey Robert L. , Staiano Michael A.
Published: October 2005

In recent years there has been a significant increase in workers' compensation payments for hearing loss claims. This increase reflects a rise in both the number of claims and the average value per claim. For example, in Wisconsin in 1970 there were 57 claims totaling $115 000 while in 1975 there were 152 claims totaling $354 000. As expected, those industries with the highest numbers of claims are those with the noisiest machines and greatest number of workers exposed. These include SIC 34—Fabricated Metal Products, SIC 35—Machinery Except Electrical, and SIC 37—Transportation Equipment. In this paper the patterns of the hearing loss claims data are discussed.
Review of research on visual speech aids for the deaf
Authors: Pickett J. M.
Published: October 2005

Visual speech aids have been designed to serve two purposes: (1) Visual feedback to a deaf person of his speech for training, and (2) display of a visual code derived from the speech signal as an aid to speech reception. Representative types of training aids will be described, ranging from a computer-based speech-training system, to a set of small training indicators for specific features of speech. Eyeglass-mounted reception aids will be described. Typical research results are presented for these aids.
Implications for the hearing impaired of computer-related research in human communication
Authors: Nickerson R. S. , Stevens K. N.
Published: October 2005

This paper discusses some possible implications for deaf persons of several areas of computer-related research and development. For the most part, this research and development has not been motivated by an interest in facilitating communication by and with deaf people. We argue that some of the results of these activities do have the potential for facilitating such communication, but that the potential will probably not be realized without explicit efforts to apply those results to the needs of deaf persons. The research and development areas that are discussed are: speech compression and speech synthesis, speech understanding systems, and computer-mediated message technology.
Measurement of head movement during auditory localization
Authors: Gilman S. , Dirks D. , Hunt S.
Published: October 2005

A system has been designed to track human-head movement response to sound originating at different azimuth locations with respect to the head. A videotape record is made of a “point-source” light carried on a small, lightweight “beanie” mounted on the listener's head. Movement of the head generates an equivalent movement of the light which is being monitored by the video camera and recorded on tape. Also, speaker location, time, and actual sound signal are recorded. Circuitry has been designed which determines the x-y coordinates of the spot image with respect to the video synch pulses. These are available from a modified video monitor either in real time or from tape replay. This same circuitry interfaces to a computer programmed to take the coordinate and timing information, apply a calibration and process the data into time-varying head position and velocity. Both digital and graphic outputs are available and examples of graphic printout of typical head movement response are given. System hardware and programs are capable of expansion into 3-axis operation.
Localization through hearing aids
Authors: Nabelek Anna K. , Letowski Tomasz , Norwood Reed
Published: October 2005

Stereophonic signal presentation was used to assess localization abilities through ear-level hearing aids. The experiment was performed in a small sound insulated room. Two loudspeakers were 2 m away from the subject forming ±30° azimuths. The subject was sitting on a chair with a head rest. He faced two strings 30 cm apart hanging on the midline between the loudspeakers and lined them up visually. Two additional strings are marked ±15° azimuths. The subject varied the position of a phantom source by controlling the relative level of signal (uninterrupted flow of speech) by means of a potentiometer. Four conditions were tested: unaided, aided with identical gains of the hearing aids and aided with the gains 10 dB different (right or left ear more amplified). Each subject made 10 adjustments for −15, 0, and +15° azimuth. Each subject was tested two times. Seven subjects with normal hearing produced unaided data similar to reported previously [(Theile and Plenge, J. Aud. Eng. Soc. 25, 196–200 (1977)]. The results for identical gains were similar to unaided results. The asymmetrical conditions produced images shifted toward the ear getting more amplification. The average shift was +4.6 and −2.6 dB for left and right ear more amplified, respectively. However the amount of shift varied among subjects. The method might have potential for testing localization abilities of hearing-impaired subjects. [Supported by NIH NISND grant.]
Study of different criteria for identifying significant amounts of threshold shift among personnel who work in potentially hazardous noise
Authors: Gasaway D. C. , Sutherland H. C. , Medina Richard L.
Published: October 2005

Monitoring the hearing of persons who routinely work in potentially hazardous noise areas serves to identify changes, or shifts, in hearing that may be attributed to excessive exposures. Since October 1956 (21 years) medical personnel of the US Air Force have used threshold shifts (current annual audiogram compared against individual reference) to identify persons who may be acquiring a sensorineural loss of hearing due to noise. Fortunately, this procedure has proven of extreme value since it identifies the occurrence of a noise-induced hearing loss during the earliest stages and thus, when combined with proper medical management, prevents the occurrence of significant amounts of hearing loss in the speech hearing range. The authors describe the results of a study of the relative effectiveness of 22 different criteria (or methods) that could be used to identify shifts in hearing (significant threshold shifts, STS) that may be attributed to excessive noise. A total of 56,678 military and civilian employees was selected for this study. The proportions of the total sample that would be identified using the different STS criteria are given; proportions ranged from 7.18% to 65.19%. Median hearing level for the total sample, as well as hearing levels for each of the groups identified by the 22 STS criteria are also reported.
Signal detection in children: ROC determination from reaction time distributions
Authors: Yonovitz A. , Lozar J. T. , Ferrell Dianne R. , Harris Bernard
Published: October 2005

The use of signal detection with children provides a precise method for investigating auditory system parameters. This study investigated the use of signal detection with normal hearing children ages 6–12. A yes-no procedure was designed such that a child could easily learn the task. A trail was initiated by the child pressing a single manipulandum. After initiation of the trial a 1-sec delay occurred. A “listen” light then occurred simultaneously with a randomly presented (0.50 probability) 1000-Hz pure tone. Tonal duration was three seconds. The child's task was to release the manipulandum if the tone was perceived. If the tone was not perceived the child was instructed to continue pressing the manipulandum. Tangible reinforcement was automatically dispensed for hits. Using this procedure a dense distribution of latencies were recorded for hits and false alarms. By redefining “yes” responses at 50-msec intervals different hit and false-alarm probabilities were obtained. These probabilities were used to construct ROC curves. This method generated a large number of points on the ROC curve with great economy of experimental time. Several stimulus intensities were used to generate functions relating intensity with d′.
Laboratory study of annoyance due to traffic noise and the choice of noise descriptors
Authors: Andrew C. , May D. N.
Published: October 2005

In this laboratory study of annoyance due to traffic noise, the equivalent sound level Leq was found to correlate more highly with subject's annoyance measured on a subjective scale than a number of other noise descriptors and subject variables. Although regression analysis showed that a number of other variables was also statistically significant (among them subject's sex, number of truck gear changes, standard deviation of the sound level, and subject's sensitivity to noise), these were not thought to add appreciably to the variance explained by Leq when the complexity of considering them in real life is considered. The experiment therefore confirms the use of Leq as a single, governing variable in determining the annoyance due to traffic noise.
Threshold shifts in chinchillas exposed to low-frequency noise for nine days
Authors: Burdick Charles K. , Patterson James H. , Mozo Ben T. , Hargett C. E. , Camp Robert T.
Published: October 2005

At the end of a three-day exposure to octave-band noise centered at 63 Hz at an octave-band level of 120 dB, chinchillas showed large temporary, and moderate permanent threshold shifts at 2000 Hz and only a moderate temporary shift at 90 Hz [Burdick et al., J. Acoust. Soc. Am. 61, S78(A) (1977)]. This was in contrast to the usual finding of maximum shift one-half to one octave above the center frequency of the exposure band. Only the half-octave frequency of 90 Hz was monitored during exposure. Consequently, nothing was known about the pattern of growth of the high-frequency shift. Also, it did not appear that the shift at 90 Hz reached asymptote as has been found for higher-frequency exposure bands. In the present study the exposure durations were increased to nine days and the growth of threshold shift at both 90 and 2000 Hz was monitored. Results confirm the high-frequency effect found previously and indicate that the shift at 90 Hz did not reach asymptote after nine days.
Temporary threshold shift in man resulting from four-hour exposures to octave bands of noise centered at 63 and 1000 Hz
Authors: Patterson James H. , Burdick Charles K. , Mozo Ben T. , Camp Robert T.
Published: October 2005

Burdick et al. [J. Acoust. Soc. Am. 61, S78(A) (1977)] presented data showing threshold shifts in chinchillas exposed to octave bands of noise centered at 63 and 1000 Hz. Their results indicated that a large temporary and moderate permanent threshold shift at high frequency resulted from exposure to the 63 Hz noise and that when the 63 and 1000 Hz noises were equated in A-weighted sound pressure levels, the 63 Hz noise was relatively more hazardous. The present study used identical exposure bands for human subjects with the exposure duration reduced to four hours. The results indicate that in man, as in chinchilla, sizable temporary threshold shifts are induced at high frequencies (1.0–3.0 kHz) by the 63 Hz octave band noise. When these results are compared to the four hour exposure point on the growth curves presented by Burdick et al. it appears that man may be as sensitive to low-frequency noise as the chinchilla. This is in contrast to the usual finding that the chinchilla is more sensitive to higher-frequency noise.
Binaural interaction of modulated noise
Authors: Burns Edward , Colburn H. Steven
Published: October 2005

The ability of observers to discriminate interaural differences in the (modulator) phase or modulation rate of amplitude-modulated wide-band noise signals was investigated using a 4AFC paradigm. Among the parameters studied were: modulator waveform; interaural coherency of the noise carriers; and modulation rate. The effect of bandpass filtering after modulation was also investigated. For the case of binaurally incoherent noise, discrimination performance for both phase and modulation rate differences deteriorated rapidly for modulation rates above about 300 Hz. This low-pass behavior is typical of that found for various monaural phenomena associated with amplitude modulation (e.g., nonspectral pitch) and presumably reflects the ability of auditory systems to utilize information from the envelope of the modulation waveform. For binaurally coherent wide-band noise, on the other hand, discrimination performance for phase and modulation rate differences were largely independent of (average) modulation rate. [Work supported by NIH.]
Binaural estimates of the phase of combination tones
Authors: Sachs R. M. , Zurek P. M.
Published: October 2005

Previous psychophysical estimates indicate that the phase of the combination tone 2f1−f2 changes rapidly as the level of the primary tone is increased. It has been suggested that this phase change, often in excess of 100° per 20 dB, is the misleading result of the cancellation procedure that has been employed in making the measurements. Accordingly, we estimated combination-tone phase (and level) using the standard monaural cancellation method as well as a simple binaural procedure. With this binaural procedure, two primary tones continuously stimulated one ear, while a subject adjusted the phase and amplitude of a pulsing contralateral probe tone at 2f1−f2 to obtain a centered image. Using a combination-tone frequency of 700 Hz, we obtained three subjects' adjustments of the phase and level of the probe, with primary levels ranging from 35 to 80 dB SPL at primary frequency ratios, f2/f1, of 1.17 and 1.3. The resulting phase versus primary-level functions for cancellation and binaural estimates were parallel in nearly all cases, and in general agreement with phase functions reported in the literature. Our results indicate that the cancellation procedure yields valid estimates of changes in combination tone phase. [Work supported by NINCDS.]
Responses of green treefrogs (Hyla cinerea) to a graded series of synthetic calls
Authors: Gerhardt H. Carl
Published: October 2005

The vocal repertoire of the green treefrog consists of a small set of discrete signals. The two principal ones are the mating and pulsed calls; the former are unmodulated and the latter are amplitude modulated (AM) about 50/sec. Intermediate calls, modulated for part of their duration, are rare. Gravid females were given choices: (1) between a synthetic mating call (UM = unmodulated) and synthetic calls which were intermediate relative to a synthetic pulsed call (M = modulated = + 7 = number of cycles of 50/sec AM) with respect to the extent of AM; (2) between the M call and two of the intermediates (+4 and +5); and (3) between the intermediates (four stimulus pairs). Females (N = 122) preferred the UM call over +2, +3, +4, and +5 but not over +1; they preferred +4 and +5 over the M call. Remarkably, they preferred +1 over +2, +2 over +3, +3 over +4, and +4 over +5. These frogs are processing these intermediate sounds in a continuous fashion. Thus the resolving power of the treefrog's auditory system provides a wide margin for error in the discrimination of its two principal calls. [Supported by NSF and NIH.]
Speech perception in early infancy: discrimination of fricative consonants
Authors: Holmberg Tristan L. , Morgan Kathleen A. , Kuhl Patricia K.
Published: October 2005

Recent data strongly suggest that six-month-olds perceive a similarity between vowels produced by different sized vocal tracts [P. K. Kuhl, J. Acoust. Soc. Am. 61, S39(A) (1977)]. This study investigates the extent to which infants recognize phonetic similarity for a fricative consonant when it occurs in different vowel environments and is spoken by different talkers. Six-month-olds were tested in a discrimination task in which fricative contrasts (/f/ versus /θ/;/s/ versus /∫/) were examined in both the initial and final positions of naturally produced monosyllables. Infants were tested in a task in which a head turn was reinforced with a visual stimulus in the presence of an exemplar from one consonant category but not in the presence of an exemplar from the second consonant category. Infants were initially trained to differentiate a single exemplar from each of the two categories; then, the number of exemplars in each of the two categories was systematically increased until each category contained 12 different tokens (4 talkers × 3 vowel contexts). Results suggest that infants are capable of recognizing phonetic similarity for consonant categories. A video tape of the testing will be shown. [Research supported by NICHD.]
Maximum noise levels of construction at heavy industrial sites
Authors: Brittain Frank H. , Norris Thomas R.
Published: October 2005

Maximum noise levels on the property line from construction activities on heavy industrial sites are typically controlled by relatively short duration or rare events, often of an impact nature. Typical of such noise sources are chipping, hammering, impact tools, ambulances, dropping of work pieces, and vehicle maintenance work. Where maximum property line levels are prescribed, a knowledge of noises from such sources is needed. This paper presents the maximum noise levels due to heavy industrial construction as measured at four sites. Available information was inadequate to predict the range of maximum noise levels. These data are presented in terms of A-weighted maximum noise levels from both day- and night-time construction activities. These results are useful when a maximum, rather than a statistical, limitation is imposed on construction noise.
Effect of truck noises on percentage of deep sleep
Authors: Thiessen G. J. , Lapointe A. C.
Published: October 2005

Sleep was divided into only two categories, “deep” and “shallow,” the latter including waking, stage 1, and dreaming. For the sake of objectivity and precision the criterion was the level of the alpha frequency and/or the audibility of spindles, from a speeded-up magnetic tape recording, which was timed by stop watch. Twenty truck noises, at a peak level of 65 dBA, presented every other night, reduced deep sleep of 12, mainly young, subjects by 3%. Adaptation of the waking response occurs despite the separation of noise nights by at least one quiet night. The small adaptation of shifts in sleep level, previously considered insignificant, still persist. Adaptation to sleeping in the laboratory appears to continue for more than the one or two nights usually assumed.
Underwater sound transmission from a fluctuating point force rotating in a horizontal plane above the surface
Authors: Hadden W. James
Published: October 2005

This paper concerns a simulation of the transmission of noise from helicopter rotors to an underwater receiver. It consists essentially of a synthesis of previous studies of the radiation in air of sound by rotating fluctuating point forces [M. V. Lowson, Proc. R. Soc. A 286, 559 (1965): C. L. Morfey and H. K. Tanna, J. Sound Vib. 15, 325 (1971)] and of the transmission of spherical waves in the ray-and wave-theory regimes from a source in air to a receiver under water [A. A. Hudimac, J. Acoust. Soc. Am. 29, 916 (1957); M. S. Weinstein and A. G. Henney. J. Acoust. Soc. Am. 37 (1965)]. The present effort extends the theory to account for cases in which the source size is not necessarily small and in which the source is not necessarily far, relative to wavelength, above the water surface. The problem is formulated via Fourier transform techniques using the field of a stationary harmonic point source as a basis for the Green's function. The solution reduces to integrals over frequency, source path, and the horizontal components of acoustic wave number. The resulting fourfold integrations are examined closely in several special cases: For force orbit radius ≪ source height and wavelength ≪ source height or receiver depth, the results are explained satisfactorily by geometrical acoustics; for orbit radius comparable to wavelength but not necessarily ≪ source height, all other conditions as for geometrical acoustics, the Green's function may be approximated as by Hudimac. The spectral density of received signals are readily computed numerically given the fluctuating force spectral density.
Total elastic cylinder cross section calculated from surface and through wave contributions
Authors: Dickey J. W. , Taylor David W. , Überall H.
Published: October 2005

The total plane-wave reflection cross section for an infinite elastic cylinder in a fluid is numerically calculated as a summation of contributions from surface and through wave modes. The various modes are separated via the Sommerfield-Watson transformation and the contribution to the total Cross section of the resulting surface waves (i.e., the fluid-borne Stoneley and Franz modes and the elastic Rayleigh and Whispering Gallery modes) are individually evaluated as residue contributions in the complex wave-number plane, and the through waves as saddle point integrals. Arriving at a total cross section in this way has the advantage of showing the relative contribution of each mode to an observation point for any set of conditions (i.e., incident wave frequency, material constants). Values of ka (wave number times cylinder radius) from 10 to 100 for an aluminum cylinder in water were used. The results indicate how resonances in individual surface wave modes cause sharp variations in scattering cross section with frequency, observer angle, and material parameters and explain the critical dependence of experimentally observed scattering amplitudes with these variables. [H. Ü. was supported by ONR Code 421.]
Theoretical study of the propagation of sound into a fast bottom from an overlying fluid wedge
Authors: Coppens Alan B.
Published: October 2005

Propagation of an acoustical wave toward the apex of a wedge-shaped fluid layer with sound speed C1 overlying a fluid bottom of higher speed of sound, C2, leads to the generation of a well-collimated beam of energy transmitted into the underlying layer with an angle of depression, θ0. While no exact solution for this beam is known to the author, it is possible to obtain a relatively simple model of the process which yields the pressure and phase properties of the acoustical wave on the interface. The interface can then be considered as a distributed acoustical source which generates the field radiated into the bottom fluid and the field can be described by the Green's function technique. Evaluation of the resultant integral is accomplished by the method of stationary phase. For wedges with very small slope β, the resulting expression is relatively simple and reveals the dependence of the properties of the transmitted beam on the acoustical properties of the two fluids quite directly: For example, the angle of depression is given by θ0 ≈ (2)1/2(β tan2θcρ2;/ρ1)1/3, where cosθc=c1/c2. [Work supported by NOSC.]
Experimental study of the propagation of sound into a fast bottom from an overlying fluid wedge
Authors: Sanders J. V. , Coppens A. B. , Netzorg G. B.
Published: October 2005

Measurements were made of the sound field produced in a fluid by a source located in an overlying, wedge-shaped layer of fluid with a slower speed of sound. The two fluids were separated by a 0.5-mil mylar sheet and the top surface was open to the air. Fluid combinations used were water over brine (critical angle 22°) and silicon oil over water (critical angle 52°). The frequencies used varied from 100 to 150 kHz and the slope of the wedge was varied from 7% on down. Beams were observed emanating from a point where the depth of the layer equals the cutoff depth of the normal modes in the fluid wedge. For angles of depression from grazing to the beam axis, agreement between experiment and theory is excellent. For greater depression angles and for slopes greater than 2% the agreement between experiment and theory becomes qualitative. [Work supported by NOSC.]
Acoustic field of a thick, fluid-loaded, composite plate owing to radiation by coupled flexural waves
Authors: Rudgers Anthony J.
Published: October 2005

An analysis was made of the acoustic radiation and reflection characteristics of a thick, composite plate, loaded on one side by a fluid. The composite plate investigated consists of two thick elastic plates joined at an interface. A flexural wave is excited in this composite plate, either by driving it with a concentrated force, or by allowing a plane acoustic wave to impinge upon it. In each of the two plates comprising the composite plate, the wavefield is described using the Timoshenko-Mindlin thick-plate equations, but owing to the coupling of the two plates at the interface, these wavefields must interact. The nature of this interaction affects the characteristics of acoustic field radiated into the fluid by the flexural wave traveling on the composite plate. In particular, it is shown that it is not possible to correctly treat the two-component composite plate as an equivalent homogeneous thick plate with artificial material properties.
Can therapeutic ultrasound damage human platelets in vivo?
Authors: Williams A. R. , Chater B. V. , Allen K. A. , Sanderson J. H.
Published: October 2005

It has recently been shown that therapeutic intensities of ultrasound decreased the recalcification time of anticoagulated whole blood in vitro. Further studies suggested that the megahertz ultrasound interacted with the blood platelets (i.e., the exceptionally fragile cells which participate in the early stages of clot formation) possibly via the occurrence of some form of cavitationlike activity. Subsequent in vitro work has demonstrated that therapeutic ultrasound can also induce platelet aggregation and the release of the platelet-specific protein, β-thromboglobulin (β-TG), confirming that the platelet is the probable site of interaction and damage. Acoustic microstreaming similar to that developed around oscillating gas bubbles has been shown to produce platelet thrombi and true clots within the intact vascular system of mice in vivo. Similarly, irradiation of the blood supply to the pinnae of anaesthetized guinea pigs with therapeutic ultrasound has resulted in the entrapment of platelet microemboli within the intact capillary bed. Consequently, a series of experiments have been undertaken to see if therapeutic ultrasound can disrupt or otherwise induce human platelets to undergo the release reaction during irradiation in vivo. A butterfly cannula was inserted into the median cubital vein of young adult volunteers and three sequential blood samples taken into iced EDTA/theophylline. The blood collected as the second sample, was irradiated with 0.75-MHz ultrasound (spatially averaged intensity 0.34–0.5 W cm−2, continuous wave) while still without the vein. No significant elevation of β-TG was observed in the sonicated samples, however, this may be a reflection of the collection procedure which did not allow enough time for the platelet aggregation-release-aggregation cycle to become established.
Recent bioeffects studies with ultrasound on the reproductive system and solid tumors
Authors: Fry F. J.
Published: October 2005

The reproductive system of the mouse and the pregnant mouse uterus studied under both pulsed and continuous wave regimes display a spectrum of responses. There is generally an increased incidence of response as the time average intensity is increased. Some notable exceptions exist to this general trend. These studies have used focused beams of 2 and 4-mm diameter at the 6-dB points. A given organ is covered by multiple-site exposure in a serial time sequence. In this way more nearly organ-specific irradiations can be conducted and paralysis due to spinal cord irradiation or anal musculature destruction is avoided for exposure at average intensities necessary to elicit the bioeffects observed in the study. A variety of ultrasound regimes have been studied and the time average intensity and exposure times reduced to the levels at which no statistically significant difference exists between exposed and control animals for the bioeffects being scored. Solid tumors grown in the hamster flank by innoculation with cells derived from a Simian medulloblastoma have been irradiated with 720-W/cm2 focused ultrasound. At 7-s continuous wave irradiation, it is possible to produce tumor extinction, regarded as a cure rate of 33%. The exposure regime has not been optimized.
Cavitation detection at megahertz frequencies
Authors: Hedges M. , Leeman S. , Vaughan P.
Published: October 2005

Onset of cavitation is monitored at ultrasound frequencies between 0.75 and 3 MHz, in both aerated and degassed media. Three different classes of criteria are used: physical effects (subharmonic generation and sonoluminescence), chemical effects (iodine release and ferrous ion oxidation), and biological effects (cell lysis and other forms of cell death). The effect of pulsing the field on these phenomena is illustrated and discussed.
Theory for bioeffects of ultrasound near gas-filled pores
Authors: Miller D. L. , Nyborg W. L.
Published: October 2005

Hydrophobic membranes with “straight-through” pores of micron dimensions provide a means of studying controlled bubble activity in aqueous media at megahertz frequencies. When ultrasound impinges on a membrane the body of gas trapped in a pore pulsates and generates a field in its own immediate locality. If biological cells are nearby, this local field interacts with them via stresses associated with radiation pressure, acoustic streaming, and related phenomena. In this paper we discuss preliminary results of calculations on these stresses, making use of available information from theory and experiment on (1) the ambient pressure amplitude pa, near a pore, taking bubble-bubble interactions into account, (2) the pulsation amplitude of a gas body in response to pa, (3) the localized fields of first and second order set up by the pulsating body, (4) the stresses on biological cells in these fields, and (5) the response of the cells. Calculations based on existing data for damage to platelets by shear stresses are in rough agreement with recent experimental findings of damage at (cw) intensities as low as 50 mW/cm2. [Work supported by the NIH via grant GM-08209.]
Intracellular temperature distribution produced by ultrasound
Authors: Love L. A. , Kremkau F. W.
Published: October 2005

The internal temperature profile of a biological cell exposed to ultrasound was found by solving the time-dependent driven heat flow equation. Three concentric spheres with different thermal conductivities and acoustic absorption coefficients (α)—each producing heat at the rate 2αI—immersed in a nonabsorbing infinite medium were used to represent one cell in a dilute aqueous suspension exposed to an ultrasonic field of intensity I. The inner sphere represented the nucleus, the middle shell the cytoplasm, and the outer shell the plasma membrane. Using representative cellular radii, absorption coefficients for beef liver nuclei (1.5 Np/cm), concentrated protein solutions (0.36 Np/cm), and erythrocyte membranes (0.9 Np/cm), an intensity of 100 W/cm2, and reasonable thermal conductivity values, a steady-state temperature of 25 m°C at r = 0 was calculated. The inner-sphere temperature had a (constant − r2) dependence, the shells had both (constant − r2) and (constant + l/r) dependence, and the outside medium had (constant + l/r) dependence. Variation of the thermal and absorption parameters indicated a stronger dependence on absorption coefficients than on thermal conductivities. Temperature rises of a few degrees were not obtained until the intensity, absorption coefficients, or the inverse of the thermal conductivity was increased by two orders of magnitude.
Absolute scaling
Authors: Zwislocki J. J.
Published: October 2005

The methods of magnitude estimation and production systematically developed by S.S. Stevens have found numerous applications. Growing experimental evidence indicates that, in these methods, the ratios of numbers associated with sensation magnitudes are nearly directly proportional to sensation ratios. A shortcoming of the methods is that the units of measurement are defined ad hoc, so that direct comparisons of absolute magnitudes are not possible. Response biases encountered in magnitude-estimation experiments in which the units of measurement were imposed on the subjects through designation of reference standards suggested that experimental subjects prefer to use their own natural units probably acquired through common usage of numbers. The hypothesis was verified in several experimental series. In particular, it was found that the inferred natural units depend little on the stimulus intensity range and the intensity of the first stimulus scaled, on whether the intensity or associated numbers are under subjects' control, or on subjects' experience with scaling. When no numerical constraints were imposed, different groups of subjects assigned the same numbers to the same loudness levels. The findings should have useful applications to measurements of loudness and annoyance. [Work supported by NIH.]
Scaling loudness and annoyance as a function of duration
Authors: Scharf B. , Horton T. J.
Published: October 2005

Both loudness and annoyance depend—under some conditions—on duration, but in opposite ways. Some data suggest that the loudness of a continuous sound decreases over time, after the first second or so. Data and common observation suggest that the annoyance of a continuous sound increases over time. To catch these changing responses on the wing, we have applied a method of successive magnitude estimation. An observer hears a continuous sound to which he assigns a number whenever a 2-s light appears. He is instructed to match a number either to the sound's loudness or to its annoyance. Results show that at low levels, as duration lengthens loudness decreases, more so for high-frequency tones, less so for low-frequency tones and wide-band noise. At higher levels, loudness remains constant as a function of duration. On the other hand, annoyance grows markedly with duration—especially during the first 15 s—but its rate of growth and magnitude seem to depend on level, spectral characteristics, fluctuations, and so forth. Successive magnitude estimation provides the data needed to sort out these interactions and so should lead to usable rules about the relation between annoyance and sound duration.
Choices among traffic sounds with equal Leq levels: A replication
Authors: Cermak G. W.
Published: October 2005

A previous pair of experiments produced a complex set of results which showed (a) that Leq, the energy-equivalent sound level, predicts choices among traffic sounds better than do other traffic noise descriptors, and (b) time-dependent sound-level variability and average frequency spectrum shape are minor predictors of choice [G. W. Cermak and P. C. Cornilion, J. Acoust. Soc. Am. 59, 1412–1420 (1976); G. W. Cermak, J. Acoust. Soc. Am. 61, S56 (1977)]. The present experiments replicate both of the previous experiments using a new set of traffic sounds. In experiment I, people judged pairs of unconstrained traffic sounds; in experiment II, other subjects judged the same sounds which had been made equal in Leq level. Results supported the use of Leq as a traffic noise descriptor, but did not support the use of sound-level variability or spectrum measures. Complex perceptual attributes of traffic sound with no simple acoustic description were the best predictors of choice when sounds were equal in Leq.