Well perhaps not wordless, but paralingual. Monique Boudreau from the unsinkable Aural Stage Studios has an incredible blog post about adding texture and depth to your audio drama through the inclusion of all the additional noises made in conversation. One of the great ways of avoiding the “talking heads” is to keep the communication consistently bidirectional through what Monique identifies as paralanguage. Have a look see for yourself at the Aural Fixation Blog and don’t forget to grunt! mime