engine noise
 

2001 XC70
A couple days ago I noticed an increase in engine noise from 30mph and up. At around 50mph the engine noise I would say is twice what it normally is. At idle I opened the hood and it sounds like something is rattling in the engine. I'm assuming that rattling sound only increases as I increase in speed thus the increase in noise. Usually the engine makes very little noise at all speeds. The car seems to run normal otherwise and I have no engine messages. Any ideas?