RESUMO
An investigation of the contribution made to an employee's noise dose from the output of personal radios was performed at a North Carolina textile manufacturing facility where the daily time-weighted average sound level (TWA) was approximately 87 dB, A-weighted sound pressure level [dB(A)]. The measured mean equivalent diffuse field output level of the personal radios was determined to be 83 dB(A) with a range from 70 to 98 dB(A). The daily TWA of a typical employee who did not use a personal radio was determined to be 86.6 dB(A), whereas the exposure of personal radio users was 88.5 dB(A)--an increase of 1.9 dB(A). This increase in exposure was estimated to result in 4 dB of additional permanent noise-induced hearing loss at 4 kHz for the 5th percentile (most sensitive portion) of the population after 20 years of exposure beginning at age 20. The study concluded that the additional contribution of the personal radios to the employee's daily TWA did not pose a significant additional threat to their hearing. Specific hearing conservation criteria, however, were recommended for continuation of personal radio use at the facility.