Two identical sources of sound $S_{1}$ and $S_{2}$ produce intensity $I_{n}$ at a point $P$ equidistant from each source.
(a) Determine the intensity of each source at the point $P$.
(b) If the power of $S_{1}$ is reduced to $64 \%$ and phase difference between the two sources is varied continuously, then determine the maximum and minimum intensities at the point $P$.
(c) If the power of $S_{1}$ is reduced by $64 \%$, then determine the maximum and minimum intensities at the point $P$.