Toilets, Sinks, Showers, Tubs and Disposals - bathroom faucet hum

Both sink faucets in the master bath make a harmonic hum when the water is turned on at anything but a very high flow. I've noticed if you push down on the faucet handle that is on the noise goes away.
I would assume it is a seal in the handles but before I go tearing into it I thought I'd seek some advice.

The reason the noise goes away is because whther you realize it or not your taking the slight vibration into your hand relieving it from the faucet. Sounds like you got build up inside or debris of some sort which isn't allowing full water volume through the valve and which explains why it makes no noise when it is all the way open.

Take the valves apart..clean em out..put it back..try again. If still doesn't work i'd replace the parts (unless they are spotlessly clean.)

if their old enough..it might save time and be more cost effective just replacing both faucets.

Remember though..this is a guess.there cold be other things that cause this. Has anything in the house been replaced lately?