Deafness due to Impulse Noise [and Discussion]

The evaluation of the hazards to hearing experienced by exposure of the ear to noise has resulted in the specification of the physical characteristics of the noise in terms of damage risk criteria. In the case of steady state and relatively long on-period intermittent noises the researches carried out have resulted in the formulation of many such criteria (Glorig, Ward & Nixon 1962; Burns 1965; C. H. A. B. A. 1965? Kryter, Ward, Miller & Eldredge 1966), the interpretation of which in terms of an internationally agreed standard is at present being undertaken by the International Organization for Standardization (I. S. O.). For exposure to very short duration steady-state noise, for noise superimposed with impulsive components, and for high-intensity impulsive noise, there is little information regarding damage risk. What does exist and the problems associated with the assessment of deafness due to impulse noise will be discussed in this paper. It must be borne in mind, however, that no criterion will clearly demark safety from danger and, being based on the light of the best available knowledge, may be subject to change as new evidence becomes available.