Hello my friend!
I am afraid I am adding to the question rather than providing an answer...
What about situations were you catch a TV, radio or other device playing on the background?
Say you record friends talking in a room but the TV is on at the same time?
To me this is part of background noise rather than THE recording in itself... So it is part of the ambience and not an intentional, useable recording of the (possibly copyrighted) broadcast that is playing in the room.
I defer the discussion to someone more versed in the details of copyright.
Of course, you can alwyas upload the sound and see if it is accepted...
Also, if you get no answers here, before giving up, repeat the question on the "Legal" help and Attribution questions forum.