13 months old baby doesn't respond his name always why

A. Mami there could be two situations if your child was previously responding knowing that this is my name and suddenly it has changed that is a problem of understanding and if your child responding 8 out of 10 times then it is okay but if it is 8 out of 10 times child is not responding then it’s a problem also it can be associated with delayed mental growth of your child in terms of understanding the situation and responding