Two loudspeakers are placed on a wall 2.00 m apart. A listener stands 3.00 m from the wall directly in front of one of the speakers. A single oscillator is driving the speakers at a frequency of 800 Hz.
(a) What is the phase difference between the two waves when they reach the observer? (Your answer should be between 0 and 2π.)
(b) What is the frequency closest to 800 to which the oscillator may be adjusted such that the observer hears minimal sound?