stage whisper
noun [ C ] uk/ˈsteɪdʒ ˌwɪs.pər/ us/ˈsteɪdʒ ˌwɪs.pɚ/
（演员有意让观众听见的）舞台旁白
If an actor says something in a stage whisper, it is intended to be heard by the people watching the play, and the other actors on the stage pretend not to hear it.
故意让旁人听到的低语
If you say something in a stage whisper, you intend it to be heard by people other than the ones you are talking to.