
That is sensetive, one of my sons hearing is quite bad, and in that region, his is 20-60dB down in that region, so over the years I've learnt a lot about speach (he had speach therapy for over 10 years). Do voices sound over sibliant.
What worries me is that noisy SPMS's are generaly badly designed and EMC transmitters, and routers are one of the most competetive markets, so I know it is one area where cost cutting is rife.
Communications over power wont help, it is basicly EMC pollution and being on the mains can get into all sorts of equipement.
The reason why i mentioned tinitus, is that I suffer from it and when it kicks in certain frequecies seem that extreme they hurt, luckily I seem to have it under control most of the time.
What make is your router.
New multiphase spread spectrum SMPS's are much better than the older style single transformer or inductor versions, but again it comes down to cost, though as you can use smaller SMD magnetics the cost difference is not as bad as it might be. But they are only now filtering down in to consumer and commercial designs, but they are critical in their layout and effectivly you have x number of controllers plus discrete components, then the spread spectrum controller and the muliphase clock generator, good fun to do.