You are walking around a large open field. the only objects nearby are two identical speakers set some distance apart. the speakers emit sound in phase with a wavelength of 4 m. as you wander around the field, you notice that at certain locations the sound you hear is surprisingly loud, whereas at others it seems unusually quiet. you conclude that you are observing the effects of interference between the two sources of sound waves. for each of the locations given, indicate what sort of interference would occur at that point?