There's no harm in having her hearing checked. That said, some babies (like mine) play their cards close to the vest. At 15 months, mine had zero words; at 18, the total number she'd said was <5; at 24, she had no two-word phrases (although she'd say multiple words separated by vast silences). She had a speech evaluation a month or so later, and was found to be way ahead in language (both expressive and receptive). She just chose not to talk.