An object that holds information about which notes have been played and which notes are currently being played. New notes are added as keys on the fly. While a note has been attacked, but not released, the value of the key is the audiovoice which is generating that note. When notes are released, the value of the key becomes undefined.
Notice any errors or typos? Please let us know. Please feel free to edit lib/addons/p5.sound.js and open a pull request!