What settings did you use when the noise floor was encoded at high bitrates? You must not use the -b parameter with vbr ;-)Bitrate in VBR encoding does not depend on frequency, but of the signal's spectral composition. If there is a lot of content that is not masked my other parts of the content you will need a higher bitrate. Examples for this are white (or pink) noise, cympals, trumpets, harpsichords, death metal etcI would not send musig through a noisegate, this sounds ugly. Better try a dynamic expansion below an appropriate threshold ...
WI would not send musig through a noisegate, this sounds ugly.
Plus, 32kbps being 95% artifact is a huge exaggeration (I just tried it to confirm).
Any bitrate spent on a very low volume section is bitrate not used on cymbal crashes, so it doesn' matter if we're uncomfortable with the idea, it's a tradeoff one way or the other whether we like it or not.