Hi, sorry if I've put this in the the wrong place!

I use the inbuilt microphone to record vocals in Garageband and have always had an amazing sound quality however today, it's playing back a really muffled sound on today's recordings.

I've looked online and as a result have tried to blow any dust from the area and also checked the mic input/output volume levels and these all seem fine (aprox middle).

Bearing in mind that I'm not technically savvy at all, if anyone has any other very step by step instructions that they could suggest I try, I'd be really grateful!

Thanks in advance.