A decibel, named for Alexander Graham Bell, is the smallest increase of the loudness of sound that is detectable by the human ear. In physics, it is shown that when two sounds of intensity I₁ and I₂ (watts/cm³) occur, the difference in loudness is D decibels, where

When sound is rated in relation to the threshold of human hearing (I₀ = 10⁻¹²), the level of normal conversation is about 60 decibels, while a rock concert may be as loud as 110 decibels.

a. How much more intense is the rock concert than normal conversation?

b. The threshold of pain is reached at a sound level roughly 10 times as loud as a rock concert. What is the decibel level of the threshold of pain?

Transcribed Image Text:

D=10 log 10 (12)