For that can hardly be in truth a whisper, which is designed to reach the ears of some hundreds of persons.

But the "asides" of the theatre are a convenient and indispensable method of revealing to the audience the state of mind of the speaker, and of admitting them to his confidence.

The novelist can stop his story, and indulge in analytical descriptions of his characters, their emotions, moods, intentions, and opinions; but the dramatist can only make his creatures intelligible by means of the speeches he puts into their mouths.

So, for the information of the audience and the carrying on of the business of the scene, we have soliloquies and asides, the artful delivery of which, duly to secure attention and enlist sympathy, evokes the best abilities of the player, bound to invest with an air of nature and truth-seeming purely fictitious and unreasonable proceedings.
But there are other than these recognised and established whispers of the stage.

Voices are occasionally audible in the theatre which obviously were never intended to reach the public ear.