Constructive/Deconstructive Sound Waves

[xregina12]

Sound waves, like light waves, can interfere w/ each other, giving max and min levels of sound. Suppose a listener standing directly between 2 loudspeakers hears the same tone being emitted from both. This listener observes that when one of the speakers is moved 0.16 m farther away, the perceived intensity of the tone decreases from a max to a min.
a) Calculate the wavelength of the sound.


I am unsure what to do with this problem. I know that sound waves can have constructive and destructive interference. I am assuming that the 0.16 m in shift has caused a destructive interference in the incoming sound waves. However, I am confused about how to calculate this. I'd appreciate any help!

 

[Delphi51]

You need a pair of diagrams showing constructive and destructive interference - like this: http://en.wikipedia.org/wiki/Destructive_interference#Constructive_and_destructive_interference
From the diagram you have to figure out by what fraction of a wavelength one source is shifted to change the interference from constructive to destructive.

 

[rl.bhat]

When the destructive interference occurs, the path difference is half the wavelength.