That's the hi-pitch sound on the headphones output when Medusa is not playing?

What you're talking about is noticeable only from the headphones output and is the autocalibration process indicated by a small dot on the middle screen of your Medusa unit. It's being commenced once in a while only when the instrument's sequencer isn't playing and when you're not touching the pads. The leaking is present due to the Dreadbox analogue board design and there's unfortunately not much we can do about it in Polyend, yet it isn't a malfunction but a hardware construction flaw. This auto-tuning leak is not present on the Master output at all.