physics help?

Question

. Two speakers are driven by the same oscillator with frequency of 220 Hz. They are located 5.00 m apart on a vertical pole. A man walks straight toward the lower speaker in a direction perpendicular to the pole, as shown below.
(a) How many times will he hear a minimum in sound intensity, and
(b) how far is he from the pole at these moments?
Take the speed of sound to be 343 m/s, and ignore any sound reflections coming off the ground?

Answer 1

This is similar to a double slit problem, however in this case it is an acoustic wave instead of light.
If l is the wave length then the vibrating in opposite directions (antiphase) will occur
when path difference is = 0.5l,, 1.5l, ,2.5l, ....he will hear minimum sound

and when the path difference = 0, l,, 2l,, 3l,, .he would hear the max.

l= v/f= 343/ 220 =1.56 m
a) theoretically any number of times considering no attenuation of the wave.
b) d= 1.56, 3.12, 4.68,... and so on