Noise from power adapter Orbi6

Hi There,

Recently installed an Orbi wifi 6 and everything is working great except I noticed a fizzing sound from the power adapters. It's a faint static noise, like a soda fizzing sound. It's coming from the adapters for both the router and the sattelite. Not the units themselves, just the power supply. 

The power supplies came with the orbi system and are Netgear branded, Input is 200-240v - 50/60hz 0.56A. Output is 12v - 1.5A

Model number AD2076100

Anyone know if this is normal?

Thanks