stage whisper
From Longman Dictionary of Contemporary EnglishRelated topics: Theatrestage whisperˌstage ˈwhisper noun [countable] 1 APTa loud whisper used by an actor in a play, which the other actors on the stage seem not to hear2 SAYa loud whisper that is intended to be heard by everyoneExamples from the Corpusstage whisper• He dropped to a conspiratorial stage whisper with Margaret: Where is she anyway?