Is non verbal communication a critical medium?

Many times it is very critical. Some examples of where non-verbal communication is critical is a traffic cop directing traffic, a safety officer on the deck of an aircraft carrier ensuring things remain safe, a detective interviewing a susptect to determine if the suspect is telling the truth, etc. On the flip side, some examples of jobs where non-verbal communication may not be as critical are radio announcers, sign makers, and plumbers.