. Vocal-auditory channel -- This means that the standard human language occurs as a vocal (making sounds with the mouth) type of communication which is perceived by hearing it. There are obvious exceptions: writing and sign language are examples of communication in the manual-visual channel. However, the vast majority of human languages occur in the vocal-auditory channel as their basic mode of expression. Writing is a secondary, and somewhat marginal form of language, while sign languages are in limited use, mostly among deaf people who are limited in their ability to use the auditory part of the vocal-auditory channel.