Loudness is measured in decibels (dB). Experts recommend that you use earplugs when exposed to 85 dB and above. The following list shows common sounds and their approximate dB levels.

• 20 dB: Ticking watch

• 30 dB: Quiet whisper

• 40 dB: Refrigerator hum

• 50 dB: Rainfall

• 60 dB: Sewing machine

• 70 dB: Washing machine

• 80 dB: Alarm clock (two feet away)

• 85 dB: Average traffic

• 95 dB: MRI

• 100 dB: Blow dryer, subway train

• 105 dB: Power mower, chain saw

• 110 dB: Screaming child

• 120 dB: Rock concert, thunderclap

• 130 dB: Jackhammer, jet plane (100 feet away)

Exposure to once-only or continuous noise can cause hearing loss. If hearing recovers, this loss is called temporary threshold shift, which typically disappears after 16 to 48 hours. Hearing loss can be permanent if loud sounds damage the cells in the inner ear called cilia. Once damaged, these cells cannot be repaired.