I will probably bring it in to dealership next week. I've been having this problem since summer but didn't get a chance (plus it would disappear sometimes).
Anyways the problem, two (2) scenarios:
(a) when moving, around 1000 - 2500 rpm, can really hear it when window is down, quiet roads, gear 2 or 3, can't really hear it in gear 1 or 4, 5. Sound is really subtle if windows are up since the cabin is great in the corollas for this generation lol... when i cruise (not gassing) i can hear it more (low rpms)
(b) fully stopped, very rarely i will hear the sound, i figured it had to do something with my clutch because when fully depressed -the sound goes away. The sound is more pronounced when I rev. One time i remember i was at a mcdonalds drive thru and i had to wait so i stopped my engine, i turned it back on and depressed my clutch and i heard it squeaking noise, it was as if my clutch pedal needed wd40 but the sound was coming from outside?... I pretty much pumped my clutch cause it was kind of funny that it was making a sound (i was stopped during the pumping)
The sound goes a bit faster when i rev, think of the rattle as a steel ball in.. another steel ball?
Also would like to mention, the sound occurs either engine somewhat hot or hot.
Need some advice, i'm not a mechanic btw and I drive a 09 corolla manual transmission
EDIT: did some googling and found this thread, it kind of relates!
http://www.customtacos.com/forum/showthread.php?t=76672
in the thread he mentions rattling, ticking, cricket sound from either throw out bearing or some fork catchin on outside of bearing
i only have 20k on my car