2000 Corolla. Ive just noticed it started making those noises in first as well. Noise goes away when it shifts into 4th. Ill try changing the fluid to see if that helps, I think the last time I changed it was 2 years ago.
EDIT: Shifted into neutral while driving and still makes that noise, but 4th/overdrive is still fine. My car sounds like a fucking trolleybus now
Also checked the fluid level and it looks pretty clean and is at the right level.