Calculate distance r_{2} where we
know the sound level L_{2} 
Sound level L_{1}
at reference distance r_{1}
dBSPL 
Reference distance r_{1}
from sound source _{ }
m or ft 
Search for r_{2}

Sound level L_{2}
at another distance r_{2}
dBSPL 
Another distance r_{2}
from sound source _{ }
m or ft 
Difference of distance_{ }
Δ r = r_{2} − r_{1}
m or ft 


