My iphone got wet in the rain and now my sound is playing really low and muffled?

It was raining and I was out and my iPhone was in my pocket, I don't even know how it got wet or it could of been a puddle that splashed but now when I play music, phone rings or text alert its very quiet and muffled and crackly or sometimes I can hardly hear anything at all. I've reset it twice now but nothing has changed
I'm just wondering if there's anything I can do to fix this and has anyone had this problem before
want to avoid paying a lot in the shop best I can

Try putting it in resealable bag with white rice and leave it in there for a few days and then check back. I have got my iPhone screen wet and it became cloudy and leaving it in the bag of rice made most of the cloudiness disappear. It may or may not help for your phone's problem.

Go to apple store and ask what's faulty in it also if you have apple care then you could get another replacement for it.
Hope this helps.