mrs overowl, this noise does it only happen when the car is moving or does it also make this noise if it is stationary with the engine revving ?. If I were you I would open the bonnet and start the engine, bring the revs up slowly to the approx amount of revs ( or more ) your car would be doing at 35 mph, listen for that noise while it is revving, if you can hear it then it is a moving part on the engine maybe a belt or a bearing on one of the moving components IE alternator bearing, air con compressor bearing or even the water pump.
If the noise only appears while the car is moving then it could be maybe a wheel related problem IE a wheel bearing, problem with a tyre or maybe one of the drive shafts.