Ugur, I think you have the same noiseI have had for years. it is worse in winter. Mine started 3 years ago at about 40 MPH, then after several months it would come at about 60 MPH. Now it may happen around either or both of those ranges. 2009 RX-350 AWD with NAV. 136K miles now. I have been through the wheel bearing deal . I always keep a spare as my Wife's Toyota uses the same one. I keep it on board on trips as I got gouged one time in CT.. I thought it came from the radio or NAV,, but once I removed both and left them on my workbench--I still had the noise! I need to remove them again, lay on my back looking up behind the glove box and find which electric box or can emits the noise. If yours is the same noise please find it and let me know. VickysRX.

 

Like we mentioned above, tires are often the culprit with speed-specific noises like this. Did you replace the tires shortly before you noticed the noise?

For me, as well, the noise was more noticeable in warmer weather - in winter, it mostly quieted down.