Importance of Spectrum for Rating Hazard: Theoretical Basis.
HUMAN ENGINEERING LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
The theoretical basis for the use of spectrum in rating hazard is well established for sound intensities most often encountered in the workplace. The frequency-selective transmission characteristics of the conductive mechanisms of the external and middle ears, coupled with the generally broad and gently sloped spectra of noise in the workplace, promote energy transmission in the midrange so that some measure of energy there should do well at ranking hazard. However, at sound pressures above 130 dB, often exceeded by impulsive sounds such as gunfire, the picture is much more complex. Conductive non- linearities in the middle ear can act to reduce the energy transmitted to the cochlea, protecting the ear and allowing it to resist damage. At the same time, however, the mechanisms of loss operating within the cochlea become very sensitive to amplitude so that relatively small quantities of energy can do permanent damage. These mechanisms are not well characterized in the frequency domain consequently, spectrum is likely to have marginal utility in rating hazard for really intense sounds. hazard rating, spectrum, impulse noise, noise hazard.
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