Explanation

Smiling is a part of nonverbal communication that is strictly linked to the paraverbal communication (voice sound)

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Related question

Verbal communication refers to the use of words for communication purposes.

It comprises both oral and written communication.

Written communication channel includes executive memos, letters, company newsletters, e-mails, Web pages, bulletin board postings, manuals, and reports.

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For traffic signs and signals, non-verbal is absolutely necessary