Answer: D) 15 minutes
The need for hearing protection depends on factors like loudness (measured in decibels), length of exposure to noise, source and the amount of movement between work areas of various noise levels.
It is most likely that the louder the noise, the shorter the exposure time before hearing protection is required. Exposure to a noise as loud as 90 decibels (dB) for an eight-hour workday is the maximum allowable before hearing protection is required. If it reaches 115 dB and lasts longer than 15 minutes, hearing protection will be required.