Under the 3 dB exchange rate, by how many decibels must the noise decrease to double the allowed exposure time?

Under the 3 dB exchange rate, by how many decibels must the noise decrease to double the allowed exposure time?

• A. 3 dB decrease
• B. 3 dB increase
• C. 6 dB decrease
• D. 6 dB increase

Answer: (A)

The 3 dB exchange rate links how a change in noise level changes the allowable exposure time. With this rate, a 3 dB change in level corresponds to a factor of two change in the permissible exposure duration. Specifically, increasing the noise by 3 dB cuts the allowable time in half, while decreasing the noise by 3 dB doubles the allowable time. Therefore, to double the allowed exposure time, you must reduce the noise by 3 dB. A 6 dB decrease would double time only twice ( quadruple the time ), and an increase would reduce the time rather than extend it.

The 3 dB exchange rate links how a change in noise level changes the allowable exposure time. With this rate, a 3 dB change in level corresponds to a factor of two change in the permissible exposure duration. Specifically, increasing the noise by 3 dB cuts the allowable time in half, while decreasing the noise by 3 dB doubles the allowable time. Therefore, to double the allowed exposure time, you must reduce the noise by 3 dB. A 6 dB decrease would double time only twice ( quadruple the time ), and an increase would reduce the time rather than extend it.