<Li> ∗ (\ displaystyle *) is the convolution operator; </Li> <Li> z is the convolution inverse of the specific acoustic impedance, </Li> <P> hence the inverse - proportional law: </P> <Dl> <Dd> p (r) ∝ 1 r . (\ displaystyle p (r) \ propto (\ frac (1) (r)).) </Dd> </Dl>

Difference between sound pressure and sound pressure level