Two sound sources emitting at the same wavelength \(\lambda\) are placed a distance \(d_{\mathrm{s}}\) apart and a perpendicular distance \(d_{\mathrm{m}}\) away from a row of microphones. Show that the distances \(\Delta x\) between those microphones that experience maximum variations in loudness are given by \(\Delta x=d_{\mathrm{m}} \lambda / d_{\mathrm{s}}\) in the limit \(d_{\mathrm{m}} \gg d_{\mathrm{s}} \).