The work of Zubrzycki is impressive. For having studied acoustics quite a bit, I'm very impressed by the fact that the sound manages to have both a very short attack an a very good sustain (thanks to the wheel). Controlling the vibration of a bowed string must have been extremely difficult... For the interested reader, there's a more detailed article here: http://tygodnik.onet.pl/zmysly/the-da-vinci-tone-in-english/...