An Investigation of the Relationship Between Occupational Noise and Hearing Loss in Firefighters

The present study was designed to measure the noise levels to which professional firefighters are exposed during the process of responding to emergency calls and to investigate the effects of these noise levels upon the auditory sensitivity of the professional firefighters . Subjects for this study consisted of two groups of firefighters at the Minneapolis Fire Department who were less than 35 years of age. Group A consisted of 17 firefighters with six months to two years of continuous paid firefighting experience. Group B consisted of 17 firefighters with eight to eleven years of continuous paid firefighting experience. An air conduction threshold test was administered to each subject at 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, 6000 Hz, and 8000 Hz. In addition, the two groups were matched with groups of the same age from data generated by Corso (1963) on subjects with normal hearing and minimal previous noise exposure. Sound pressure levels were recorded in the cabs of nine firetrucks of the Minneapolis Fire Department. The readings were obtained during response emergencies, utilizing the A and C weighting scales, and the octave bands, 31.25 Hz, 62.5 Hz, 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz. The overall average time in a 24-hour shift to which firefighters were exposed to fire apparatus noise while responding to emergencies was calculated from nine 24-hour log sheets. Three log sheets were collected from each of three fire stations randomly selected in Minneapolis. The results of the hearing threshold tests indicated that there was no significant difference (p \u3e .05) between the auditory sensitivity of Group A and Group B. Comparisons were made between the thresholds obtained for Group A and the same age group in Corso\u27s data; and between the thresholds obtained for Group B and the same age group in Corso\u27s data. A significant difference was present at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz for both comparisons. However, there was not a significant difference at 6000 Hz and 8000 Hz for either comparison. The results suggest that exposure to the short duration of intense fire apparatus noise does not significantly affect the auditory sensitivity of firefighters. Some implications for further research in this area are discussed