A.K.
I would definitely ask your pedi, but some kids just talk later than others. I had my son evaluated by ECI when he was 2 because I thought he was slow to talk, but he actually ranked at a 3 year old level. Give it some time, but if he is still having trouble at 15 months, I would call my pedi and get his hearing checked first and then an ECI evaluation if all is well there. Try to relax though...soon you will dream of the days when you didn't hear - "MOMMA!" at insane decibel levels!
:) Hang in there!