Speech refers to pronunciation, pace and melody. It can happen that different sounds are not pronounced correctly, or that there is a stutter, monotonous speech or sounds are mixed too much. The muscles of the oral area not being strong enough could cause these problems, where the tongue and lips are not functioning the way they should. Different sounds are mixed or replaced by other sounds. This greatly reduces audibility.

Stuttering can also influence audibility.

A neurological disorder, such as a apoplexy,  can also be the cause of a disruption of speech.

It sounds as if a person talks with a thick tongue. This sometimes involves a face dropped to one side. This we call dysarthria.