I remember driving 150km in a car, quizzing myself about a really weird squeaking sound, sometimes most apparent when turning left, other times under acceleration etc etc - it jumped around and drove me nuts. I stopped several times, but couldn't find any apparent reason, so I had to carry on.
The next weekend I was doing a brake cleaning/pad check, and found a piece of steel wire had entangled itself to the right front caliper, hidden from casual sight, but quite apparently the reason the for noise. :-)
In my Peugeot 106 spare-car (called TinyCar, and responds to the name :-) ) I one day had a really annoying buzzing rattle - well a NEW one, and simply couldn't make out where it came from. Sounded like something in the passenger side door, but driving alone made it difficult to check. I emptied all compartments for stuff that could rattle, and convinced myself nothing was loose anywhere, and STILL it rattled...
Until one day my son was driving, and whether his ears are better than mine (they probably are), or pure luck, he discovered that the gear lever's connection was the cause. Put your little finger on the lever and move it 1cm to the right, and the rattle was gone! NICE
It just shows that noises can origin from the most improbable sources, - uneven tyres (even balanced tyres can vibrate if the tyre is poorly made), unbalanced driveshafts, gravel or as in my case steel wire caught where it shouldn't be etc.
Just a story, - not that I expect that to help you much.
/Lennart