You are standing 5 feet from one speaker and 14 feet from another. Both speakers are producing the same sound. If the combined sound from both speakers is barely audible at your location, which of the following could be the wavelength of the sound?

Answer 1

your distances from the speakers are different by a half wavelength (this is the reason for the sound "cancelling")

14 - 5 = 11

so the sound wavelength could be 22 ft