It is a consistent issue for wood workers how to quieten down the extractor! The CamVac system has an optional exhaust tube that is surprisingly effective at damping down the noise, I used to run a record power DX1000 inside an OSB constructed cupboard lined with acoustic foam which helped a bit! I now have a High Flow Low Pressure chip extractor which is a different pitch of sound that is not quite so piercing, that is housed outside the workshop in an acoustically insulated extension but for that to work it needs large diameter ducting (5" on mine) and still I can't use it in the evenings!
Only plus side is dust extraction only works on dust, so pretty much only needed for sanding so by planning my work I can aim to be making shavings in the evenings save all my sawing, routing, and sanding for day time when the neighbours are less likely to notice!