I am just starting with a Nexus 30. I got it ready to go and had some great help making sure everything was OK for the first flight. It ran great and the first attempts at hovering are going well, still need MUCH MORE practice but I love it so far! I noticed a ringing that stay consistent just before the heli is getting ready to hover and it stays when it leaves the ground. It only goes away when I bring the throttle back down. It's a high pitch like ringing in the ears. Any ideas what it could be?

I used to fly with the late great Mr. Laurel Koll (I was flying planes, and drooling at his flying ability!) his heli never made a noise like this. I wish he were around to ask cause I am sure he would know.