People who cannot talk may be referred to as mute or nonverbal.
Charlatans.
Therapist
People with schizophrenia may talk a lot. If they talk a lot without making much sense, this is called "schizophasia".
autism
the word is shy
Conversing, conversation, dialog.
talk slowly and do what you have to do to keep contact
It's called communication. No talking, no communication.
An Elephant Called Slowly was created in 1969.
Telepathy
talk quietly talk slowly talk fluently talk clearly talk loudly talk openly talk secretly This is not all there must be many more