Vibration sense is one component of touch. Refinements of this sense, and in some animals the emission of vibration – typically from the vocal cords – has evolved to echolocation, to clicks, grunts, roars and to speech.  The vibration of one special membrane, the ear drum, creates that wonderful interface that enables us to appreciate and locate sounds in 3-dimensional space and to discern what the source of that sound is.… read more »