Noise when driving

I've got a 2007 Touring with 40k miles on it. Never had any issues until about 2k miles ago, when we started noticing noise while driving on the freeway. The higher the speed, the louder the noise. It starts to be noticeable at about 40mph and gets really annoying at 65 - 75mph. It seemed to come from the RH-side, and the dealer was quick to blame it on out-of-alignment tires. Dealer 'investigation' was about 2k miles ago.

We've changed and aligned the tires this week; alignment on all four corners was almost within tolerances (off by a small amount). I've also changed the oil, since it was due.

Nevertheless, the noise is still there; now it seems to have 'moved' directly in front of the driver.


What could it be?

 

> Try noticing if the sound changes depending on whether you are turning left or right.
Yes, I've tried that already; I think the noise got worse while I was hard cornering a left turn (loading the right wheel, where I thought the noise was).

Vibration in the steering wheel also makes me think it may be one or both bearings. But at only 40k?
I'll try to post an audio recording.

 

I did the following:
1) Put the car on jack and checked both LH and RH front wheels for "play", i.e. bearing wear. They are as tight as they come. At this point I believe it is not bearing wear.
2) Made a video recording, the audio of which I uploaded here. The noise frequency is dead-on 200Hz and I amplified that by about 10dB for clarity:
https://dl.dropboxusercontent.com/u/19552319/Recordings/Prius%20Noise.mp3
I drove freeway, 60 - 75mph, then city, around 45mph. While on the freeway, I put the car in Neutral, then back in Drive several times. Noise didn't change at all.

> ursle: Have you had inverter water pump replaced under warranty?
I believe so, twice. The first time, under the warranty recall. The second time I was complaining about noise after turning off the car, when the coolant gets pushed back into the storage reservoir. Pump noise is fine.

> ursle: causing inverter/transaxle to overheat.
Hmm, that's interesting. The noise does increase in level the more I drive the car, i.e. from cold it is not too bad, but after 5 minutes of driving it gets to its above-recorded level.

> ursle: It could be one of your CV joints.
Checked the boots, they look like new. The whole underside looks like new, the car has been well cared for.

Is there any kind of warranty covering the Synergy Drive?

 

The steering intermediate shaft was replaced under recall. The noise was there at recall time, and they said it's an alignment issue, like stated.

 

Inverter reservoir flow flows just like in this video:
Prius inverter turbulence - TeacherTube

Not too ripply, not too quiet, just about right.

 

Hmm, sounds like the same symptoms as here, but definitely no wiggle in the front wheels when on the jack. The old tires were evenly worn before changing them as well.
Transmission noise | PriusChat