Subvocalization (repeating information quietly to ones self) helps those with short term memory deficits to recall spoken information.

Two methods that are used to improve reading speed is chunking and eliminating subvocalization. There are books, videos, seminars and software that can be used to help you achieve speed reading.

Moving the lips while others are talking could be a sign of subvocalization, where a person silently repeats the words they are hearing in order to better understand or process the information. It could also be due to a habit or a way to stay engaged in the conversation.