gradual transition between white noise and a sine tone

Hi,

I'm trying to make a gradual transition between white noise and a simple sine tone and I am basing my patch on the gen~ random example, I edited the gen file:

a noise generator is scaled so it drives the frequency of a cycle object from 0 to 22050 Hz and it is doing it in speed from 0 to 44099 Hz(at 44100 it blows up somehow). At the highest speeds I expected to get pure white noise but when I compare my output with an output of the usual MSP [noise~] object I see that there is a spike in the high frequencies and the sound is more hissy than the normal white noise.

Can someone explain why?