Hearing threshold was reexamined in a group of forge hammering workers investigated 8 years ago with consideration of the age effect and of auditory symptoms. Workers were exposed to impact noise that ranged from 112 to 139 dB(A)--at an irregular rate of 20 to 50 drop/minute--and a continuous background noise ...

Adverse effects of simultaneous exposure to visible light and room temperature were investigated in rabbit early cleavage stages and morulae. Routine laboratory conditions were mimicked as close as possible. Embryonic development was assessed by cell proliferation via incorporation of tritiated thymidine, by gross morphology, and by electron microscopy. Damage was ...

A review of the theory of absorption on microscopic and macroscopic levels is given. This theory is then applied to the absorption of UV light by diazo-type positive photoresist during exposure. A formal treatment of the properties of polychromatic light is given. Using these analyses, the effects of polychromatic exposure ...

Two-dimensional (2-D) gel electrophoresis has been used to follow changes in cell type specific and organelle localized polypeptides upon exposure of etiolated sorghum shoots and dark-grown resting Euglena to light. Total protein extracted from isolated bundle sheath strands and mesophyll protoplasts was resolved by 2-D gel electrophoresis. The cell type ...

An analysis of the pure-tone threshold recovery functions obtained from 118 chinchillas exposed to high-level impulse noise showed that there are at least three distinctly different types of recovery function: type I--a recovery function for which the initial threshold shift recovers monotonically with increasing postexposure time; type II--a delayed recovery; ...

Aftereffect measures of visual shift and proprioceptive shift were obtained for prism exposure conditions in which, at the end of a sagittal pointing movement, most of the arm was visible (concurrent exposure) or only the first finger joint was visible (terminal exposure). Intermediate exposure conditions permitted view of the hand ...

Guinea pigs were pre-exposed to a low level acoustic stimulus prior to exposure to a stimulus known to yield a permanent threshold shift. This pre-treatment resulted in: 1) approximately a 20 dB reduction in the threshold shift relative to animals not pre-exposed, and 2) complete recovery from the threshold shift ...

Gap detection thresholds (GDTs) were obtained from human listeners before and after exposure to a brief 0.4- or 1.7-kHz tone. The temporary threshold shift (TTS) produced 2 min after an exposure was approximately 10 dB. GDT stimuli were octave-band noises centered at one of three frequencies: the exposure frequency, one-half ...

Previous studies have determined that severe systemic hypoxia disrupts cochlear function acutely, but have suggested that augmentation of cochlear perfusion may successfully protect cochlear function under all but the most profound hypoxic treatments. In the current study we report on the chronic effects of simultaneous exposures to noise and carbon ...

The effects of intense noise exposure on hearing in the budgerigar were examined by behavioral audiometry. After binaural exposure to an intense broadband noise, auditory threshold shifts (TS) of the birds were continuously measured at frequencies between 0.125 and 8 kHz using an avoidance conditioning technique. Temporary threshold shifts (TTS) ...

Sixty patients with varying degrees of noise-induced hearing loss (NIHL) after long-term exposure to intense impulse noise from firearms, but without manifest clinical symptoms of vestibular pathology, were tested for body sway using a stable platform. The results were compared with those from 115 healthy referents examined in the same ...

This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at ...

Rats were exposed to toluene (1000 ppm, 16 h/d, 5 d/w, 2 w), or noise (100 dB Leq, 10 h/d, 7 d/w, 4 w) or toluene followed by noise. Auditory function was tested by brainstem audiometry using a 1/3 octave filtered sine wave stimulus at the frequencies 1.6, 3.15, 6.3, ...

Exposure to light was recorded from 10 healthy elderly adults and 13 age-matched subjects with senile dementia of the Alzheimer's type (SDAT). Data were recorded in the home, for an average of 5 days, while subjects continued their normal daily activities. Subjects were exposed to remarkably small intervals of illumination ...

The aim of the present investigation was to determine: 1) the relationship between changes in auditory sensitivity and alterations in stereocilia micromechanics and tectorial membrane morphology after acoustic overstimulation; 2) the rate of growth of a threshold shift in stereocilia following in vitro overstimulation; and 3) if the damaging effects ...

Exposure to electromagnetic fields may cause various types of effects on nervous tissue, in severe cases even irreversible damage. The exposure conditions, i.e. frequency including type and extent of modulation, time, intensity, wave form, as well as shape, size and position of exposed subject and possible treatment with drugs, are ...

Changes in hearing sensitivity and cochlear damage were determined in two groups of chinchillas exposed to an octave band of noise (OBN) centered at 0.5 kHz, 95 dB SPL on two different schedules: 6 h per day for 36 days, or 15 min/h for 144 days. Hearing sensitivity was measured ...

Whole nerve action potential (AP) and single auditory-nerve fiber thresholds were measured in chinchillas exposed to noise. The exposure stimulus was a 500-Hz octave band of noise presented at 95 dB SPL for 15 min/h, for 4 or 40 days. The AP thresholds were elevated by about 40 dB on ...

A dry polymeric mixture rendered red sensitive with a dye has been used to record interference gratings and holograms. Diffraction efficiencies of ~10% can be attained with exposures of ~94 mJ/cm(2). If necessary the reading step can be done just after the exposure or after a fixing step performed with ...

In this study we assessed the influence of duration of exposure of the Rorschach stimuli on the response determinants when the information processing is interrupted using a patterned mask or visual noise. Analysis shows that increasing duration of exposure does not yield a parallel increase in the production of more ...

12 male and 12 female volunteers were evaluated for their suggestibility before and after an approximately 15-min. exposure to either sham, 1-Hz or 4-Hz magnetic fields that were applied across their mid-superior temporal lobes. During the field-application subjects were instructed to view a green light that was pulsating at the ...

Guinea pigs were exposed to the impulse noise from 90-300 rifle shots (peak 158 dB SPL, maximal energy content at 1.1 kHz). This exposure induced severe cochlear damage. The vestibular end organs also showed damage of varying degree. The ampullary cristae were most severely damaged, but changes were also seen ...

The findings of a number of studies investigating the effects of excessive sound on hearing have indicated that the correspondence between behavioral, physiological, and histological measures of noise-induced hearing loss may be markedly dependent upon the sensitivity of the particular measure. Recent studies demonstrating significant changes in the responses of ...

Forty-one chinchillas, divided into seven groups, were exposed to 1, 10, or 100 noise impulses (one every 3s) having peak intensities of 131, 135, 139, or 147 dB. Hearing thresholds were measured in each animal before and after exposure using an avoidance conditioning procedure; a surface preparation of the cochlear ...

In a case-control study of 209 workers from a local railway maintenance and repair workshop, pleuropulmonary lesions were studied on chest radiographs. All workers were known to have been exposed to asbestos fibers of all kinds for a long period of time, but the exposure was light. A "dose index" ...

Psychophysical tuning curves (PTCs) at 2 kHz and auditory thresholds (2 kHz and 4 kHz) were obtained from 18 normal-hearing listeners before and after exposure to a 5-min 110 dB SPL white noise. PTCs were quantified on five dimensions (Q10 tip, Q10 probe, d1oct, tip level and tip frequency). PTCs ...

This experimental study was designed to determine whether a combination of noise and vibration produced more pronounced changes in temporary shifts of finger skin temperature and temporary threshold shift (TTS) of hearing than those resulting from exposure to either stress alone. Nineteen healthy subjects were exposed to six different combinations ...

The effect of 60 minutes of exposure to high-frequency (10- to 40-kHz), high-intensity (115-dB) noise on the cochlear blood flow (CoBF) was investigated in adult gerbils. The CoBF was measured with a newly improved microsphere method. The number of microspheres in cochlear tissue that had been dissected by the surface ...

Single-unit recordings were made from populations of auditory-nerve fibers in 12 cats before and after acoustic overstimulation. Cats were killed 4 to 16 h after exposure, and the cochleas were analyzed at the light- and electron-microscopic levels. The exposures were designed to create 40 to 60 dB of acute threshold ...

Changes in the auditory nerve action potential (AP), evoked responses from the inferior colliculus (IC-ER) and auditory cortex (AC-ER) were assessed after exposure to white noise of 120 dB SPL for 1 h in awake guinea pigs. Auditory thresholds were estimated with the aid of averaged AP, IC-ER and AC-ER, ...

A systematic study of the effects of acoustic overstimulation on the endolymphatic sac (ES) in the guinea pig was performed. The ES was studied with light and transmission electron microscopy after exposure of the animals to a 3.85 kHz pure tone of 108 dB SPL or 120 dB SPL for ...

Reversible tinnitus was induced in 10 male and 8 female normal-hearing subjects following a 5 min 110 dB SPL exposure to white noise. Temporary threshold shift (TTS) was measured at 2 and 4 kHz. Characteristics of the tinnitus were determined by means of a written questionnaire administered 5 min following ...

Temporary Thresholds Shifts were assessed in five groups from before to after 5-minute exposure to 110 dB SPL white noise and in one additional group without noise exposure. In each group the baseline conditions were designed to elevate psychological stress via anticipation of the noise and venipuncture procedures. In the ...

Four groups of chinchillas were exposed to an octave band of noise with a center frequency of 4 kHz and a sound pressure level of 80 or 86 dB SPL on interrupted schedules with 18, 42 or 162 h of rest between successive 6-h exposures. Damage in these ears was ...

Hypoxia has long been hypothesized to play a role in noise-induced hearing loss, and the disruption of auditory function by asphyxiation has been repeatedly demonstrated. Recent data, however, suggest that the cochlea is resistant to less extreme hypoxic events. The current report describes the combined effects of noise and hypoxia ...

It was predicted that because the ear is spectrally tuned, it should be most affected by intense impulses with spectral peaks near the frequency where it is tuned best (3.0 kHz for the human ear) and progressively less affected by impulses at lower frequencies [G.R. Price, Scand. Audiol. Suppl. 16, ...

Evidence that reduced levels of cochlear melanin are associated with increased auditory sensitivity, increased levels of auditory fatigue and an increased susceptibility to noise-induced hearing loss led us to investigate the effects of noise exposure on the cochlear microphonic (CM) in albino and pigmented English shorthair guinea pigs. CMs were ...

Sensory hair bundle micromechanics were measured from all four hair-cell rows in the isolated guinea pig cochlea before and during overstimulation. The stereocilia bundle was stimulated by an oscillating water jet, and stroboscopic illumination slightly offset from the frequency of the stimulus revealed their motion. The intensity of the water ...

In the Province of Quebec, the regulated daily noise exposure limit is 90 dBA-8h. This limit value also applies to pregnant women. Experimental studies suggest however, that this standard is not sufficiently stringent to protect the auditory system of the fetus, particularly in cases of low-frequency noise exposure. An exploratory ...

Alligator lizards were exposed to broadband noise ranging in intensity from 106 to 132 dB SPL for two hours and permitted to recover from 19 to 62 days. Hearing loss was assessed by comparing the auditory nerve component of the cochlear potential recorded at the end of the recovery period ...

Temporary threshold shift was examined in 10 voluntary subjects who were exposed on 5 occasions to noise only and on 5 additional occasions to noise after intake of 1 g acetylsalicylic acid (ASA). The results showed no evidence that moderate doses of ASA potentiate temporary threshold shift. Subjects tested before ...

The psychophysical effects of sound stimulation at increasing intensity include adaptation, temporary threshold shift, and permanent hearing loss. The mechanisms involved in permanent loss are direct mechanical destruction, following high intensity noise exposure, and metabolic decompensation with subsequent degeneration of sensory elements, following moderate intensity noise exposure. Both these cause ...

The equal energy hypothesis (EEH) was evaluated over a limited range of conditions by exposing four groups of chinchillas to impact noise (200-ms B duration) presented at a fixed rate of four impacts per second. The intensity of the impacts (107-125 dB peak SPL) and the duration (120-1.87 h) of ...

We examined the effects of 1-min tonal exposures on the amplitude of the 2f1-f2 distortion product in the ear canals of cats. These effects were compared with the changes in the whole-nerve action potential (AP) responses to tone bursts following similar exposures. Both the distortion product and AP amplitudes were ...

The results of social surveys conducted near three airports that support both general aviation and scheduled air carrier operations are presented and discussed. Inferences supported by these data include: The nature of noise exposure and community reaction at smaller airports may differ from that at larger airports; survey techniques are ...

A compilation of reports of biological effects and related ultrasound exposure levels can be useful in the identification of trends in effects data that may be developing in the literature. The exposures in the experiments reviewed were at frequencies used in medicine. For short (10 minutes or less) continuous wave ...

This study determines how the magnitude and pattern of cochlear damage is altered when exposure to noise is interrupted by regularly spaced rest periods. Groups of chinchillas were exposed for six hours per session to an octave band of noise with a center frequency of 0.5 kHz. The rest interval ...

Noise-induced changes in the compound action potential (CAP) evoked by tone bursts in the frequency range 0.5-24 kHz were studied in 15 pigmented guinea pigs by means of chronically implanted electrodes positioned near the round window. The animals were exposed for 120 h to continuous pink noise at the intensities ...

Noise-induced alterations of the click-evoked compound potential (CAP) were studied by means of electrodes chronically implanted near the round window in 15 pigmented guinea pigs aged 3-6 months. The potentials were recorded before, during and after exposure to continuous pink noise maintained at an intensity of 80, 90 or 100 ...

Low-tone exposure elicits four distinct dips in hearing thresholds: one octave above the exposure frequency, in the permanent threshold shift (PTS) range, at about 10-11 kHz, and at 14-15 kHz. While dips 1, 2 and 3 decay as a function of the time log, dip 4 has a much longer ...