If play returned a reference to the play function you could chain them like .play('D#5', 1/4)('E5', 1/4) Just a thought on cleaning up the syntax a bit.
A cleaner way may be to allow the play() method to accept a plain JS array of notes:
var notes = ['D#5', 1/4, 'E5', 1/4];
or
var notes = [['D#5', 1/4], ['E5', 1/4]];
beeplay().play(notes);