The intensity of sound at a point P is I_0 , when the sounds reach...

The intensity of sound at a point $P$ is $I_0$, when the sounds reach this point directly and in same phase from two identical sources $\mathrm{S}_1$ and $\mathrm{S}_2$. The power of $\mathrm{S}_1$ is now reduced by $64 \%$ and the phase difference $(\phi)$ between $\mathrm{S}_1$ and $\mathrm{S}_2$ is varied continuously. The maximum and minimum intensities recorded at $P$ are now $I_{\text {max }}$ and $I_{\text {min }}$ such that