Peugeot 307 1.6 Sport (Petrol) - Peugeot 307 Noises - gazzaman

I've got a 57 plate 307 and it was great until the winter just past, when I heard a hum/resonance coming from my back driver wheel area. I took it to several garages, mist of which could not hear it during a test drive, which meant they were unable to fix something they could not hear, which I suppose is fair enough. My problem is, as people that have been in this situation know, that it is really annoying to me and is spoiling the enjoyment of the car.

This started in March 2010 and by June, I had had enough and replaced the entire back brakes (which on the 307 includes the wheel bearings), which was no cheap job. Much to my dissatisfaction, this did not help. Before you all start shouting at the screen, that it is tyre noise, its not, as I have tried 3 (count them) different makes of tyres and the noise is identical.

Braking does not interrupt it, so it is not related to that, but the noise is cyclical, like it is something in the caliper or it could be a vibration, and so I though, is it the spring...

This is where I need your help, not to fix it, but how to diagnose whats wrong. So far I have had a laptop in my boot recording noise, and I have captured it quite well, so at least I know it is something under or near the wheel arch.

Is there a place that could run the back tyres up to speed whilst being able to check the components with a mechanics stethoscope to isolate the noise?

Things are getting desperate, and I was looking at ways of dampening components to isolate the noise but as you may have guessed I am not mechanically minded and don't want to continue to splash cash around only for mechs to say they can;t hear it..

So to summarise, humming noise at 20mph and above (quite subtle) rear drivers. Brake.disk, pads and bearings changed. Tyres changed (3 times).

PS I don't want to trade it in...quite yet