Hello forum,the link on the http://music.columbia.edu/percolate/ page is broken ,anyone got the windows version please drop me an email MinjuGingiu at gmail.com. Thank you

hello,please excuse the n00bish question,I'm very new to this.
I just discovered this strange effect on osc <30 hz,there's this relativelly high pitch artefact which I can't explain that changes in pitch if I change the freq of the osc ~.
I get the same with synthesising in Max , Wavelab and Sound Forge but not with Plogue Bidule x). I suspect it has something to do with amplitude because I've seen in Wavelab the artefact appears at extrema points of the sinusoid. Are this only partials which are the only thing hearable since the fundamental freq is so low? And if so,how can I get ride of it withut filter?
Thank you in advance .