Yeah I like it better that way, seems more smooth. Still a bit hokey on recognition, but it remains an awesome idea.
I've managed to find the problem with the recognition / jerkiness. I'm detecting pitch in the frequency domain, which can suffer from pitch doubling: it sometimes thinks you're singing an octave higher than you are. This is why it could jump around a lot while moving downward - it thought those low notes were much higher.
Anyway, I'm trying a new version that does a SingStar and only cares about the note you sing, not the octave. You need finer voice control but the game is way more playable. I'll add a gui component to show the current note and update the original jnlp.
Thanks for all the testing guys!

Edit: The webstart in the first post (
http://www.cs.auckland.ac.nz/~jteu004/freqflier/freqflier.jnlp) now loads a version that controls by note, not absolute pitch. A "C" is max speed down and a "B" max speed up. A "G" will keep you stationary while increasing the multiplier.
I've also added a bar at the top shows where it thinks you are singing.