A speaker is the utterer of a message.
A speaker is typically the deictic center of his or her own deictic references. These are grammaticalized in first person morphemes.
Levinson, Stephen C. 1983.Pragmatics. Cambridge, England: Cambridge University.
Fillmore, Charles J. 1975.Santa Cruz lectures on deixis: 1971. Bloomington, IN: Indiana University Linguistics Club.