There are references in some of Shakespeare's plays to the vocal exercising of an actor before performance and the importance of enunciation and volume.
National Theatre: Voice Work with Jeannette Nelson
This is the first of four films demonstrating how to warm up your voice, focusing on breathing exercises. Breathing exercises are an essential start to any vocal ...
Vocal Warm-Up #1: Breathing
Jeanette MacDonald & Nelson Eddy singing, "Indian Love Call," from the 1936 film, "Rose Marie."
Jeanette MacDonald & Nelson Eddy: Indian Love Call