Actually.. make it mandatory? I like the idea. It's probably much easier to recognize audio patterns than visual ones (at least it seems so for me). Alternating tones would probably make me go insane though so I'll just go for the constant on/off :)
Amos, I don't think it should be mandatory (especially since things like the manual aren't mandatory) but I'll try and reword the rules so it's more encouraged.
Having it be mandatory feels a bit odd, since then it'd automatically be an "audio-focused" jam. Audio isn't the norm - visual display is the "standard" mode of feedback. "bit jam" would no longer feel as descriptive as something like, say, "beep jam".
I'm glad it's an option, though!