The commonly used unit of measurement to judge volume level is the decibel (abbreviated dB). Everything from a gentle sliding touch to a revving engine makes noise which has volume. What we experience as volume is actually air pressure being affected by an action and tiny sensitive hairs in our ears register this change in air pressure sending a signal to our brain.
Unfortunately, those tiny hairs are very sensitive and prolonged exposure to audio at high decibel levels can cause permanent damage.
The decibel scale is a logarithmic value, a sound 10 times more powerful than 0 dB is 10dB. A sound 100 times more powerful than near total silence is 20dB. A sound 1,000 times more powerful than near total silence is 30dB.
Here are some common sounds and their decibel ratings:
Whisper Quiet Library
Normal conversation (3-5')
Telephone dial tone
Level at which sustained
exposure may result in
Walkman on 5/10
Power mower at 3'
Loud Rock Concert
Exposure WITH hearing
Jet engine at 100', Gun Blast
90 - 95dB
Any sound above 85 dB can cause damage or hearing loss. Damage is related both to the power of the sound as well as the length of exposure. You know that you are listening to an 85-dB sound if you have to raise your voice to be heard by somebody else.
Statistics for the Decibel (Loudness) Comparison Chart were taken from a study by Marshall Chasin , M.Sc., Aud(C), FAAA, Centre for Human Performance & Health, Ontario, Canada. Additional information from www.hyperacusis.net.