Stopping whining isn't that easy.
 

Normally I like wine but this one is leaving a bad taste in my mouth.
95k miles on a 2012 Q5 and the whine has been getting steadily worse over the past couple of months.
It's road speed related not engine dependent. It starts at 20mph and just gets louder with speed. It sounds like like a light aircraft noise on a sunny day.
You listen carefully in the car but can't really say for sure where it comes from. All you know is that it's very annoying.
You swing left and then right but barely can tell any difference. (maybe very slightly less when turning left).
So I replaced the left front bearing cuz that was the hottest wheel after a long run and I convinced myself that the sound was more to the left.
It had zero effect.
I put the car up on 4 jack stands, put it in drive and ran it in idle. The rear wheels make a noise but it sounds more like brake pads scuffing the rotor than a bearing noise.
I put a makeshift stethoscope on the hubs but could hear nothing.
I could only really get the front wheels to rotate (on engine power) with the parking brake on.
I crawled underneath and listened with the engine/driveshaft rotating and there was no unusual sounds from the shaft.
So now I'm stuck. Where is this whine coming from? I'd almost like to say it's coming from the center of the car where I'm guessing the front diff is. But if I cup my ears and rotate like a radar antennae I can convince myself of various sources. My main guess is from the left side. But I don't want to replace the rear left bearing so quickly as it seems a bit more involved than the front and I'm not even half confident that's it.
So here we go with 6 hours drive to Cleveland and 6 hours back and a vintage whine all the way!!
Anyone with an idea?
Mark

This has located all my elusive noises over the years. Works very well. It takes two people, driver, and a listener to switch the microphone positions back and forth.

My father had a Subaru Outback that had a front wheel bearing noise but we couldn't tell which one even swaying left and right in a parking lot. We both agreed that it was most likely the right side, but bought
this gadget and it immediately indicated that it was the left side bearing. Save us a lot of grief. Now friends and family come to me when they have strange vehicle noises and we always locate where they are at. The best one was a guy with an occasional loud rear knock. The dealer couldn't find the problem. Hook up the Chassis Ear and located that it was the rear top strut mount. I have used it around the house also on rattling water pipes, heating circulating pumps, etc.

Money well spent.............

How many miles on your tires? Do you run them at proper inflation? How's your alignment?

Sounds like tire noise to me.

Bob's suggestion for the ''electronic ears" is a good one. I had a set in my business and they saved a lot of time. Things like wheel bearings can be real sneaky. When your spinning unloaded wheels on a lift they can be silent to the stethoscope. Nowadays these "ears" probably exist with Bluetooth mikes that do away with the spaghetti.

Which engine do you have ?

Is it always there at certain speeds? On my 2010 Q5 I have a whine between 67-72 mph. If I go above or below that speed, it doesn’t really bother me too much. I had it looked at by the dealer but they couldn’t pinpoint anything. After ruling out tires and wheel bearings, I did some research that points to the center differential bearing as a possibility. But since it doesn’t seem to affect operation (over 100k miles), I’ve just dealt with it.

Teetotal, i.e. no more whine!
 

So the whine was bad all the way to Cleveland and got worse all the way back.
It was very hard to guess where it was coming from.
When I got home I researched differential bearings but there was very little written about them so they obviously didn't fail very often. I then took my (video camera) radio mic and clipped it in various positions around the car, crawling underneath each time to re-position it and then go for another test drive. It was incredibly loud in most places (I had no volume control without plugging it into a video camera.) All I could decide was that it definitely wasn't from the back and was probably loudest on the front right.
In desperation I went ahead and ordered the right front wheel bearing. At least I figured I'd eliminate it as a possibility. Another $90 put out.
Today I removed the bearing and it looked wonderful. Rotated smoothly etc etc.

While I had the driveshaft disconnected at the outer end and was feeling depressed, I glanced in toward the other end where it went into the differential. At that end it has a square end with four bolt heads. There is an aluminium bendable heat shield around the diff and a corner of it was bent back and it looked to me like it was touching the bolt heads as the driveshaft rotated! Now, I'm sure that wasn't it, and it must have been that pristine bearing I replaced even though I then whacked that heat shield far from the driveshaft.
Unbeleivable! I have no idea how it got like that.

I just put the car back together and went for a perfect whine-free run. Hallelujah! But I have sneaking suspicion I just wasted $180.

Good catch!

Just feel good that you found the issue and you happen to do a little preventative wheel bearing maintenance.

That better then replacing the wheel bearing and not noticing the bent heat shield.

One would think that the rotating bolts hitting the aluminum shield would wear a clearance very quickly, the noise would at least get quieter over time. My bet is that it was the bad wheel bearing. You were successful and now drive in peace!

It's a matter of perspective. Look at this way: You only had to spend $180 to fix it. In the world of German car ownership, that's cheap; not much more than two oil changes.