I take it they are using a lavalier microphone during lectures that broadcasts the recording in an unencrypted format? If so, that's a great solution.

Yeah, they are using Sennheiser transmitters (some are lavs some are full XLR mics ) Basically, I am using an SDR(RTL-SDR V4 with a small antenna) and SDR++ they have set frequencies that I have bookmarked and saved.

Funny thing, this allows me to listen to courses in other rooms, its quite fun to tune in and guess the class xD

I absolutely love these little capabilities that (cheap) SDR opens up to pretty much everybody.