Even in toddlers that ARE more verbal that your child, head banging is a fairly common emotional reaction in children your son's age. And, as the first comment suggested, you really do just have to ignore it. Children engage in the types of behavior because (a) they lack verbal communication skills and (b) it gets a HUGE reaction from their parents. In fact, the more you give credence and freak out when he bangs his head, the more often and violent the head banging may become. You may try distracting him with another activity when he begins the head banging, but if he is insistant upon doing it, leave the room. Honestly - if you aren't there to watch or react to his tantrum, he won't find it necessary to continue as it does not get the desired effect from you that he wants.
Now, the fact that your son only has one word at 16 months is concerning. I am a special education teacher and child psychologist, and this language deficiency can be a symptom of something more serious. Does he avoid direct eye contact with you, and others? Does he engage in unusual, repetitive activities such has hand flapping or stroking/touching/petting specific items? Does he become engrossed in a single, simple activity such as looking at the same page of a book, for a long period of time? Does he walk on his tiptoes? If you think that he is exhibiting any of these behaviors, you should take him and have him immediately evaluated by a specialist - they are common signs of autism. Head banging is also common in children with autism, but the head banging would have to have been accompanied by more of the above mentioned symptoms.
Some children are just naturally late talkers, but I would suggest talking to your pediatrician about your concerns. If you notice any of the symptoms I mentioned above, talk to your doctor. Otherwise, the head banging is normal and something to be IGNORED, just like a temper tantrum.