Question

A person wears a hearing aid that uniformly increases the intensity level of all audible frequencies of sound by 30.0 dB. If the hearing aid picks up a sound with an intensity of 3.5 x 10^-9 W/m² , what is the sound intensity delivered to the eardrum?

Answer 1

$$L=10\lg\frac{I}{I_0}$$

$$I=I_010^{L/10}\\ =3.5*10^{-9}*10^{30.0/10}=3.5*10^{-6}\:\rm W/m^2$$