There could be various reasons that could cause sound distortion to your wireless speakers and they are as follows:
Make sure Bluetooth transmission (example: bluetooth file sending from phone to phone) is not performed within the area of the Home Theater System as it will cause interruption to the wireless signals.
Change the channel on the HTS to see if the problem persists:
Press OPTIONS. [ General Setup ] menu is displayed.
Press down to select [ Audio Setup ], then press right.
Select [ Wireless], then press OK.
Select [ Switch Channel ], then select the channel you wish to change into.