Anybody knows a better abstraction for noise reduction than the one in the audio.examples?

The one in there makes a lot of funny noises after the amount of noise to be masked goes over a particular point. I know this is happening because the higher the amount of noise is the more partials are to be masked, which cause the sort of spectral distortion I am experiencing. I can't really think one but was wondering if there is any "trick" to sort out this problem?