I didn't mention just pitch shifting alone without speed change as depending on how that is done it can introduce artifacts. So just slowing things down like an oldschool tape player is the most 'pure'.

Any computer sound card will high-pass anything over about 16-18 hz and thus new lower stuff won't swamp, and it seems like his implant amplifier does indeed deal with low frequencies because he mentions using an 18hz tone to keep the device key'ed on.

Another thing then to mention would be 'binning' audio that has been pitch shifted own using notch filters / comb filters. Because it is possible that however the implant is wired could use some band gaps to help his brain 'decode' things more clearly and less muddy.

Again, all this is simple shit and I find it really surprising that there isn't someone to help run these tests on hardware with this person, and their blog post here has this very strange rabbit hole feel to it and I can't tell if it is because there is a lot lost in translation, or if there is a lot more to this that is coming across in translation... or if this person in being led down some near-AI-psycosis and is struggling because they simply don't have someone to sit with that can help.

It all comes off to me as very, very strange.