Hi, Two loudspeakers are connected to the same audio oscillator. An observer walks in between them. At a point M, halfway between the speakers he hears a loud sound. By the time he gets to a point P 2m away from M he hears no sound at all. Calculate the maximum wavelength of sound emitted by the loudspeakers. This is what I did: If 2 m there is no sound at all, there is destructive interference, hence: (n + 1/2) λ = 2. The maximum wavelength would be equal to 4, but the book says 8 m. How? Thanks, Peter G.