Paralingual means

     Some people tend to speak through clenched teeth and with little movement of their lips. It is this inability to open mouths and failure to make speech sounds with precision that is the root cause of inaudibility. The sound is locked into the mouth and not let out.

     To have good articulation it is important to unclench the jaw, open the mouth and give full benefit to each sound you make, paying attention to the ends of words. This will also help your audience to understand.