Failure of noise exposure to modify temporal patterns of plasma cortisol in man.

The purpose of this investigation was to assess the modification in the temporal pattern of plasma cortisol levels during exposure to noises of different intensities, frequencies and durations. Plasma cortisol concentrations were measured from 08.00 h to 15.00 h at 10 min intervals in eight subjects on a control day and one or two exposure days. Noise exposures induced no significant increase in plasma cortisol concentration. It is concluded that noise, at "safe" levels for human hearing conservation, when not associated with other potentially noxious stimuli does not cause hyperactivity of the pituitary-adrenocortical system. These results do not tally with those from animal studies where noise is known to activate corticotrophin (ACTH) secretion.