By how many decibels does the sound intensity from a point source decrease if you increase the distance to it by a factor 6?

Answer 1

A rule of thumb: About 3 db each time one halves sound intensity. But sound intensity changes as 1/r^2, so, 6 is changing sound intensity by 1/36

db= 3*number doubles
but 8- 2*2*2
and 4=2*2

so, 36 is 8*4
log 36= log8+log4=3+2=5

so,going down by 3 db five times, or -15 db about...

Check: 10 log 1/36= -10 log(36)=down 15.56 db the sound goes down