Did anyone hear the Repub debate tonight? What was that noise?! (Details)

I tuned into the second hour of the debate (or discussion or whatever it was.) As I was listening, I kept hearing this grunt (I know this sounds funny, but I did) it was this continuous “uh..uh..uh..uh…” or some low grunt and it was incredibly distracting. It almost sounded as if someone was talking in low tones over the responses.

(Okay, I am listening to Anderson Cooper’s after debate show right now and in the replays you can still hear it.)

Did anyone notice this?