Answer
Drops by 6 db
Explanation
The Inverse Square Law states that in a free field for every doubling of the distance from the source, the intensity of sound drops by 6 decibels. As the intensity of sound is inversely proportional to the distance squared.
The intensity of sound ∝ 1 ∕ distance squared.
I ∝ 1 / d2
Here, ∝ is ‘proportional to’
I is the ‘intensity of sound’
& d is the ‘distance from the source’
