1) model headphones
2) the nature of the noise
3) where did the idea of grounding? and especially USB hub
Wang: not very expensive motherboard, bad power supply filtering USB ports that are "singing" noise. Where interference is also an important issue. Either from the mains or the computer itself geranium (e.g. HDD or optical drive, if present. the power fans also sometimes give background).
It is possible that it can help just filter the power outlet (extension cord with filter. by the way, read what they are, from just a stupid capacitor to quite a interesting schemes). This is the easiest and painless, maybe not the cheap but simple.
In the second case is more complicated. May (just may) help USB hub with external
power supply. Usually PSUs have their filrouge chain and they can drown out some noise. Or himself on the basis of the USB extension cable to make a home-made, by including in the circuit a simple LC filter (capacitor with inductance). There are ready-made and quite compact options such as time
If you are very lucky there will be enough such that the ferrite ring:
If you can not wait, then a sample can be taken apart some non-working charger and use a pulse transformer - SMATV all the windings and wound a couple of rings of wire of their headphones.