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Biomedical subjects

T I Hempstock

Publications and source records attributed to T I Hempstock.

6 recordsLinked to original sources
PubMed1990

The attenuations of some hearing protectors as used in the workplace.

A sound field which conforms to the requirements of ISO 4869 (1981) has been created in an audiometric booth which has been installed in a mobile trailer. This trailer has visited industrial sites where protectors, which were being used in the workplace, were tested. Work people, selected at random, were tested in a procedure similar to that specified in ISO 4869. The occluded and unoccluded thresholds of hearing were measured and then used to estimate the protector attenuation. Results from a number of muffs, plugs and helmet-mounted muffs, tested in the workplace, show that, in most cases, the attenuations were less and the standard deviations were greater than those quoted by manufacturers from laboratory ISO 4869 tests. The implications of these results for the selection of hearing protectors are discussed.

Attitude to Health↗
PubMed1986

Accuracy of measuring impedance in the hand-arm system.

In an assessment of the accuracy with which impedance can be determined in the hand-arm system, two subjects were each tested six times at 28 frequencies between 10 and 800 Hz. In addition the effect of wearing an air cushion glove was investigated, and an attempt was made to develop a simple model of the glove. The results showed agreement with other recently published data for impedance in the hand-arm system at frequencies above about 25 Hz but not below. The mean values of the impedance for a single subject had standard errors of about 10%. When the subjects wore an air cushion glove, there was only a small change in impedance, and consequently in the total amount of energy dissipated in the hand-arm system. A simple mass-spring damper model of the glove predicted that the attenuation provided by the glove was minimal, except at the highest frequencies.

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