Question

Moe, Larry, and Curly stand in a line with a spacing of d = 1.40m . Larry is 3.00m in front of a pair of stereo speakers 0.800m apart, as shown in the figure(Figure 1) . The speakers produce a single-frequency tone, vibrating in phase with each other.
What are the two lowest frequencies that allow Larry to hear a loud tone while Moe and Curly hear very little?

Answer 1

The two lowest frequencies that allow Larry to hear a loud tone while Moe and Curly hear very little are the frequencies that create a standing wave between the speakers and Larry. The two lowest frequencies are given by the equation f = v/2d, where v is the speed of sound and d is the distance between the speakers. In this case, the two lowest frequencies are f1 = 343 m/s / (2*1.4 m) = 96.07 Hz and f2 = 343 m/s / (2*3.0 m) = 48.03 Hz.