$108.$ Two identical speakers that face each other and that are separated by a distance of $2\mathrm{.}00$ m emit a constant tone in phase. You stand in line with the speakers such that your right ear is exactly halfway between the two speakers, resulting in your left ear being closer to one speaker than the other. You notice that what you hear in your right ear is loud, but in your left ear you hear almost nothing. Given that your hearing is fine in both ears and the distance between your ears is $16\mathrm{.}0$ cm $,$ what are the two lowest frequencies that the speakers could possibly be emitting? Example $13-5$