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Results for “Ear Protective Devices”

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At least 577 records · Page 32Linked to original sources
PubMed1989

[Hearing protection against noise in the stomatologic clinic].

On the basis of current analyses of the noise situation in the stomatologic practice proposals are made for noise control. An newly developed personal ear protector is especially taken into consideration. Furthermore, the possibility of using wide-band absorbers is presented to reduce the room sound level.

Dental Clinics↗
PubMed1989

Aircraft noise-induced temporary threshold shift.

Audiograms were taken on 20 young men before and immediately after exposure to Fighter-6 ground running-up noise, and their course of recovery was followed. The sound levels at the engine hatch were 117-128 dB(A). The noise-induced temporary threshold shift was more than 13 dB. The maximum threshold shift occurred at 4 kHz. The shift in the low and speech frequencies recovers more rapidly and is completed in 30 min, whereas that in the high-frequency range recovers much more slowly, not returning to normal until 24 h later. High-frequency hearing loss is at risk in groundcrew. In order to prevent hearing damage, they ought to wear ear-protectors. We discovered that the V-shaped depression was not at 4 kHz but at 6 kHz. The former view concerning the pathogenesis of "4 kHz depression", therefore, is open to question. This interesting subject warrants further study.

Adolescent↗
PubMed1989

[Effect of occlusion. Part II. Theoretical and practical implications].

The theoretical and practical consequences of the experiments described in part I are discussed. They concern the following topics: 1. The stability of the occlusion effect: in contrary to the opinions expressed in the literature--the stability of the effect for a particular earphone is of range of normal deviation in threshold of hearing. 2. Bone conduction threshold shift in occlusion effect represents change in proportions of the air- and bone-components of the normal bone conduction threshold: an increase of the air component on the expense of the bone component. The shift do not represents the change in perception. In that respect the shift is a spurious phenomenon. 3. Depending on the presence or the lack of occlusion effect all the ears were divided into classes: "occlusive" and "non-occlusive". a) the occlusive ears include the ones with normal conduction (healthy or the hearing- impaired ears) covered with earphones during bone conduction tests, b) the non-occlusive are the ears mentioned under "a", but unoccluded and all the ears with conductive loss (regardless the occlusion). The audiometric norm for bone conduction threshold, established in non-occlusive state (which is the usual procedure in the conventional audiometry) are suitable only for the non-occlusive ears. And vice versa: the occlusion norm (found in a routine Rainville procedure) may be applied only for occlusive ears.

Audiometry↗
PubMed1988

Speech intelligibility in difficult signal/noise circumstances.

In practice, subjects wearing ear protectors often give contradictory statements about the possible distorting effects of ear protectors. We tried to simulate some difficult background circumstances by arranging five different signal/background noise combinations (five S/N ratios). Speech discrimination tests made in these circumstances with and without ear protectors could reflect the real capacity to understand orders or messages in difficult hearing situations. 52 Finnish speaking conscripts with normal hearing from 18 to 24 years age were selected to participate in the test on a day without any noisy training duties. The test words in the Finnish speech discrimination test in combination with corresponding white noise were produced by equipment consisting of a high quality tape recorder, an audiometer, an amplifier and loud speakers. The test were performed individually in free field in a sound proof room in the Hearing Centre of the University Central Hospital of Oulu. The subjects listened to the test words with all the S/N ratios [S/N = 60/70, 55/70, 65/70, 60/75 and 65/75 dB (A)] with and without ear protectors. At the signal/noise ratios 60/70 and 60/75 dB the words were perceived relatively poorly with and without hearing protectors. At the signal/noise levels of 65/70 and 65/75 dB the protectors turned out to produce highly significantly better word discrimination. At the signal/noise level of 55/70 dB the discrimination is very poor in both cases but significantly better without ear protectors.

Adult↗
PubMedDate not supplied

Sound remedies.

Explore the source record for details and available documents.

Auditory Perception↗
PubMed1987

[Risk of noise-induced hearing loss caused by radio communication? Audiologic findings in helicopter crews and pilots of propeller airplanes].

The affects of noise on the human inner ear have been well known for a long time, and measures to prevent occupational noise-induced hearing loss show a clear reduction in the statistics of morbidity. Nevertheless, there are working environments in which the use of ear protection seems to be inapplicable, because communication by speech is indispensable, for example in the cockpit of aircraft. Noise exposure measurements were performed on pilots of helicopters and propeller-machines of the German Federal Navy during realistic flight situations. The ambient noise levels during regular flight service were maintained at levels between 89 dB and 120 dB. Sound protection by flight-helmets and headphones is not only neutralised while using radio and intercom, but the noise during radio-communication is even louder than the noise of the engines. The use of ear protection to avoid excessive noise exposure is only of limited effectiveness. While pilots with normal hearing show only little impairment of speech intelligibility, those with noise-induced hearing loss show substantial impairment that varies in proportion to their hearing loss. Communication abilities may be drastically reduced which may compromise the reliability of radio-communication. The problem may be possibly solved in future by an electronic compensation system for noise.

Aircraft↗
PubMed1987

[Significance of the low tone test in the detection of probands sensitive to noise].

Studies on the susceptibility to noise of 186 ears using the deep-tone test showed, after exposure to impulse noise of very high intensity, no difference in the reaction of the ear in persons with positive and negative deep-tone test. Until now no significance of the deep-tone test has been established with regard to susceptibility to noise.

Audiometry↗