dead air

1. A period of unwanted silence during a television or radio broadcast caused by an unintended interruption or malfunction. A technical glitch during the Super Bowl led to several ads being replaced by a blank, silent screen, dead air that may cost those companies thousands—if not millions—of dollars.

2. By extension, any period of awkward or uncomfortable silence. A horrible dead air hung over the room after Jonas finished reading his poetry to the crowd.