Physics and Chemistry

Light, Sound, and Other Waves

What is a decibel?

A decibel is a measure of the relative loudness or intensity of sound. A 20 decibel sound is 10 times louder than a 10 decibel sound; 30 decibels is 100 times louder, etc. One decibel is the smallest difference between sounds detectable by the human ear.

Decibel Level Equivalent
10 Light whisper
20 Quiet conversation
30 Normal conversation
40 Light traffic
50 Loud conversation
60 Noisy office
70 Normal traffic, quiet train
80 Rock music, subway
90 Heavy traffic, thunder
100 Jet plane at takeoff


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