Note to Macbeth, Act 1, Scene 6, opening stage direction: "Hoyboys"

Act 1, Scene 6.
A very persuasive article, Ominous Oboes, on the Finding Shakespeare site argues that this stage direction, "Hoyboys," is one of the first uses of atmospheric music. The author points out that the same stage direction is used twice more in the play: once in the next scene, during which Macbeth commits to killing King Duncan, and again just before the witches summon up the apparition which tells Macbeth that the descendants of Banquo will be kings.

Image Source:
Ominous Oboes