The effect of recreational gunfire noise on hearing in workers exposed to occupational noise.

Hearing sensitivity for an experimental group of 278 industrial workers who engaged in recreational shooting was compared with that of an age-matched control group of 278 nonshooting industrial workers to examine the effect of gunfire exposure on auditory thresholds. The influence of age and the number of unprotected gunshot exposures per year also was examined. The subjects in the experimental group completed a questionnaire to define the types of firearms used, the number of years shooting, and the number of protected and unprotected gunshot exposures per year. Results revealed that hearing sensitivity for frequencies 3.0, 4.0, and 6.0 kHz for both ears in the experimental group was an average of approximately 5 to 10 dB poorer than that of the control subjects. Although both subject groups demonstrated poorer 3.0-to-6.0-kHz hearing sensitivity for left-ear compared with right-ear listening, the degree of asymmetry between ears was greater for the experimental subjects. Older shooters had more hearing loss and greater threshold asymmetry than younger shooters, but there was no significant relationship between hearing sensitivity and the number of unprotected exposures per year. This latter finding was attributed to a fourfold increase in the number of unprotected annual exposures that were reported by younger shooters, who had inherently better hearing than did the older shooters.