An effect analogous to two$-$slit interference can occur with sound waves, instead of light. In an open field, two speakers placed $1\mathrm{.}30$ m apart are powered by a single$-$function generator producing sine waves at $1200-$Hz frequency. A student walks along a line $12\mathrm{.}5$ m away and parallel to the line between the speakers. She hears an alternating pattern of loud and quiet, due to constructive and destructive interference. What is $($a$)$ the wavelength of this sound and $($b$)$ the distance between the central maximum and the first maximum $($loud$)$ position along this line?