Under a 3 dB exchange rate, how does the exposure time change when the sound level changes by 3 dB?

Under a 3 dB exchange rate, how does the exposure time change when the sound level changes by 3 dB?

• A. The time is halved when the level increases by 3 dB, and doubled when it decreases by 3 dB
• B. The time doubles when the level increases by 3 dB, and halved when it decreases by 3 dB
• C. The time remains unchanged
• D. The time increases by 10% for every 3 dB

Answer: (A)

Under a 3 dB exchange rate, exposure time changes by a factor of two for every 3 dB change in sound level. A 3 dB increase roughly doubles the sound energy, so to keep the same total energy dose, the allowable exposure time must be halved. Conversely, a 3 dB decrease halves the energy, so you can double the exposure time. This is why the correct statement is that time is halved when the level goes up by 3 dB and doubled when it goes down by 3 dB.

Under a 3 dB exchange rate, exposure time changes by a factor of two for every 3 dB change in sound level. A 3 dB increase roughly doubles the sound energy, so to keep the same total energy dose, the allowable exposure time must be halved. Conversely, a 3 dB decrease halves the energy, so you can double the exposure time. This is why the correct statement is that time is halved when the level goes up by 3 dB and doubled when it goes down by 3 dB.