Ringing , high pitch noise inside cabin
 

When I am in my car with it running I can hear a slight ringing noise but can't tell where it comes from. It doesn't change with the rpm. And doesn't matter if radio and climate control
Are on or off , it's just easier to hear with them both off. I can't hear anything outside the car. Only inside. It doesn't always do this. Any ideas?

I hear the high pitch sound in my 2008 LS460 as well. I've googled previously but didn't find anything on it. On a whim, I googled again today and saw your post. Have you found the source or a solution yet?

Are any of the seat heaters on in the car?
I found that in my 430 I could hear the seat heater fans until the day I cleaned the filters.

Ditto, dfkd. Shortly after we got our LS 430 I heard the high-pitch noise too. Eventually I realized it was the seat fans. I replaced both seat filters but still hear the sound. I don't hear it in the LS 460 though when using the heated or cooled seats and I thought the 460 doesn't have seat filters.

I think it's the stereo.
Yesterday I went to take a quick siesta and had the car on with the stereo off. Reclined the drivers seat and the high pitched noise got really loud. Turns out it was coming from the tweeters in rear doors. Unsure if this is normal or not. Can you guys see if you're able to replicate the problem?