dead ear
Dead ear is radio and television lingo which is used to describe a moment of unintended silence on air. This usually occurs when someone says or does something dumb or uncalled for, which prompts silence from the listening party, almost always because they don't know how to respond to the dumb comment. Or it could also mean awkward silence in which something was expected.
In 1987 Dan Rather gave CBS six minutes of dead ear when he walked off the set in a fit because a tennis match ran overtime, cutting off part of the news.