What is producing the bass sound?

[Annoying Twit]

Is that a bass string I see on this guitar?

http://www.youtube.com/watch?v=YaIN13aDbCc

If not, where is the IMHO very nice and fitting occasional simple bass accompaniment coming from?

[HowieBass]

I think that's all Michael Hedges - when he's had people like Michael Manring accompany him on (mostly) fretless bass, they're usually visible on stage.

[RhysP]

Hedges used to use some unusual tunings with very low (for an acoustic guitar) bass notes, not uncommonly G below the low E.

[leschirons]

And one of the true masters of the Harp guitar. A really sad loss to music. I think he had so much more to offer. The guy was a genius.

[Annoying Twit]

Thanks all. Surely for a G below low E, he would have to use a high gauge string, or it would just flop around uselessly?