sounds like something loose under the passenger side speaker. Can't find it HELP thanks

 

That is a pretty vague description of the sound you hear lol, I wouldn't even know where 2 begin giving ideas...

 

Have you removed the speaker? If so try shaking the speaker and make sure the coil isn’t separated. That could cause a rattling sound. Otherwise the best bet would be to take the door panel off and start shaking things to see if you hear it.