Having worked with very young children for many years, I have encountered this concern more than once. You are correct in thinking that 16 months is a little late, but it is not beyond what is considered "normal" on a developmental timeframe. First, you need to rule out a few fundamental things: do you know if she hears well or not? Pay attention to that , and tests such as clapping your hands a ways behind her when she is not looking can also give you an idea of her hearing. If you think there might be a problem, have her ped conduct a hearing test.
If there is no question that there is a hearing problem, the BEST way to encourage your child to speak is to speak constantly to them. Describe to them everything you do when they are with you, and ask them questions pertaining to what you're doing to encourage her to make conversation. You may feel a little silly at first, but all mommys understand! Describe things in detail, and be super interactive with the object/task you are at. And don't talk to her like you were talking like another baby: talk to her like she understands everything you say to her (and she probably does). My daughter is 17 months old, and while she was an early talker and now has a crazy big vocabulary, she still chit chats in baby talk a great majority of her time - like its her language, and she just speaks english when she needs too! Read often if you have the time: this also encourages the learning of a wide array of simple vocabulary. Im also a HUGE fan of sesame street, it really does encourage young children the basic building blocks of language in a way that theirs brains can process and then reproduce what they hear. My daughter watches one episode of sesame street (1 hour) once a day, and I have noticed a HUGE leap in simple words as well as counting, abc's, and visual recognition of letters and numbers.
So try a few things - but if you are really concerned, take her to her ped and see what he/she has to say!