Glitch theremin sound

[kklmsk]

My theremin is making this glitch/twitching sound when I am not playing (or sometimes when I am playing too) and it really annoys me. Is this some sort of hardware issue or just my room is too small and something is interfering with the pitch antenna? I've posted a video in this reddit thread that you can check out how it sounds like https://www.reddit.com/r/Theremin/comme ... t_playing/