inside voice

[ in-sahyd vois ]

noun

1. a modulated, relatively calm voice, considered polite and socially appropriate when speaking indoors, as at home or in school or in an office ( outside voice ):

   The students were reminded to use their inside voice and not shout their responses in class.

Word History and Origins

Origin of inside voice¹

First recorded in 1975–80

Example Sentences

So remember your inside voice, and leave some air in the room for others to breathe.

From The Daily Beast