Still no 1st word...

Sarah

My daughter is 15 months and though she is energetic, playful, etc... She has yet to communicate any words. No mama or dada... nothing. She hums along with music once in a while. She LOVES to clap and I always say YAY when we do it together but she still won't even say that with me. I know every child develops on their own schedule but should I be concerned that she isn't saying even a single word at her age yet?