Abstract
Relative efficacy of various levels of enforcement in the use of personal hearing protective devices was investigated among employees of a large industrial plant. The main variable was that each of four groups of employees worked during a different period of enforcement policy on the use of personal hearing protection. Analysis of variance of mean hearing levels using three different audiometric grading schemes with different levels of sensitivity, namely, the 0.5, 1, 2 kHz Hearing Level Index, the 1,2,3 kHz Hearing Level Index, and the 4000 Hz single puretone test indicate that the enforcement policy did have a dramatic effect on the efficacy of the hearing conservation program and should give similar results in other industrial settings. When and where the use of personal hearing protection was left to the employee it was found that hearing loss among the noise-exposed was very much in excess of that among a non-noise-exposed group. Mandatory use of personal protective devices was found to be much more effective in conserving hearing than the voluntary approach. Mandatory use of earmuffs exclusively proved to be less effective than mandatory use of personal hearing protection when the employee was given a choice of earmuffs or earplugs. Enactment of the Occupational Safety and Health Act did not result in greater hearing conservation over the existing company mandatory hearing conservation program which is quite effective.