Decibel is the unit of

How many times more intense is $90\, dB$ sound than $40\, dB$ 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 $dB$)?

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

In an orchestra,the musical sounds of different instruments are distinguished from one another by which of the following characteristics?

Four sources of sound each of sound level $10\,dB$ are sounded together,the resultant intensity level will be ... $dB$