Audio-Technica has an online Checking Frequency Compatibility application available for this purpose. Check the squelch control setting on the receiver. A higher squelch setting provides better protection against interference. However, since a high setting also can cause a reduction in operating range, set the control to the lowest position that reliably mutes the interference. Make certain that all batteries are fresh and new.
Weak batteries make a system more susceptible to interference.
Turn off unnecessary electronic equipment, especially computers and digital devices. These are a relatively common cause of wireless interference. If interference does occur, see Resolving Interference Problems for suggestions on solving the problem. Additional information about Types of Interference is also available.