Speech problems are not only related to hearing problems. My son is reaching 2 years, and while his progress in his speech therapy is excellent, it's a tough thing to deal with. It may very well be a 'big deal' if your child is not saying any words at 18 months. I feel so lucky that my pediatrician ordered a speech evaluation at his 18 month visit. The earlier you can start speech therapy, the better.
Every month makes a difference.
Push for an evaluation if your child isn't speaking. I am becoming concerned. She clearly does not have a hearing problem, she will turn her head when she is called by her name and will bounce when music is turned on. That is if she is turning her head when you call her name, more than likely she doesn't have a hearing problem. Remember, children develop on different levels and milestones at different times.