The contribution of communications signals to noise exposure

Man-mounted miniature recording equipment has been used to measure the electroacoustic conditions obtaining in cockpits of aircraft and at the pilot's ear during operational sorties in the Royal Air Force. Although this paper considers the measurements taken that relate to the total noise exposure (noise dose) received by aircrew, the results apply equally to anyone who is exposed to high noise and requires communications. Comparison of the noise at the ear with the cockpit noise gave a measure of headgear attenuation which was used to adjust a [Formula: see text] filter. Playing cockpit noise tapes through this filter to a noise dose meter gave the noise dose that would have been experienced had there been no communications signals. The results showed that the communications signals at the ear, averaging 40% of the sortie time, are a major contributor to the total dose, and, without the signals, the dose averaged about 6 dB less. In view of the Health and Safety at Work Act, 1974, employers should be aware of the additional dose to which employees are exposed because of communications. A method for the prediction of noise dose is proposed where communication takes place in a noisy environment.