The sound level at a point 5.0 m away from a point source is 40 dB. What will be the level at a point 50 m away from the source ?
We know that, β=10log10(II0)
(a)βA=10logIAI0βB=10logIBI0
⇒IAI0=10(βA10)
⇒IBI0=10(βB10)
⇒IAIB=r2Br2A=(505)2
⇒βA−βB10=2log10
⇒(βA−βB10)=20
⇒βA−βB=20
⇒βB=40−20=20dβ