Pretty neat! I've heard those beeps a lot but never knew what they were for. Also, is it me, or do the sounds in the example recording sound the same? (frequency-wise?)
Thanks! Listening to the recording, I'm reasonably sure I can distinguish the two different frequencies, but there's no denying they sound very similar. They're so close there's less than a semitone between them.
The output quality is terrible, very crackly (on chrome and firefox). I don't see any reason for that in the code so I assume it's just due to the way web audio is in general. I can understand why it isn't used more often.