Quality (or timbre) of a sound depends on:

Decibel is the unit of

$A$ sound absorber attenuates the sound level by $20 \ dB$. The intensity decreases by a factor of

How many times more intense is a $60 \ dB$ sound than a $30 \ dB$ sound?

$A$ group of people watch an ice show held in a closed area. Skaters perform a music show whose sound level is $60 \ dB$. $A$ spectator can yell at $40.0 \ dB$. Which one of them represents the approximate combined sound level (in $dB$)?

The intensity level of a sound whose intensity is $10^{-8} \ W/m^2$ is: (in $dB$)