I had a simliar situation not too long ago, but a bit closer to home. I was in the circuit doing downwind checks and I missed the call from ATC instructing an orbit. My excuse is that I was new to the aircraft and was trying to figure out if fuel pump on was switch up or down. Didn't tell the controller that. Just said "G-xx go ahead" The tower had a distinct "yoohoo are you there" tone. Embarrassing, dangerous, poor airmanship, etc. Live and learn.
D