The word (or in general any sign) is interindividual. Everything that is said, expressed, is located outside the "soul" of the speaker and does not belong only to him. The word cannot be assigned to a single speaker. The author (speaker) has his own inalienable right to the word, but the listener also has his rights, and those whose voices are heard in the word before the author comes upon it also have their rights (after all there are no words that belong to no one). The word is a drama in which three characters participate (it is not a duet, but a trio). It is performed outside the author, and it cannot be introjected into the author.
(M.M. Bakhtin, "The Problem of the Text" in Speech Genres and Other Late Essays)
I like that word: "inderindividual." I should note that this particular essay remains as notes and not fully fleshed out. Yet this concept can be found throughout Bakhtin's works: speech is something between three. A speaker speaks, but the speech is not "monologic" because the speaker anticipates a response. This anticipation affects the speech itself and what "speech genre" will be used in the "utterance" (see the "Problem of Speech Genres" in the same volume). This makes the listener an active participant. The listener listens, to be sure, but waits to respond, and, thus, becomes the speaker. But, again, this is not a duo, but a trio. Others have already modeled and molded the speech patterns, the types of speech to be used on a particular occasion to elicit a particular response (the speech genre). Words belong to no one, or, better yet, belong to everyone. So, when speaking, it is not just "ich und du," but within this dialogue, the "tertium quid" is all the previous usages heard in the speech, whether deliberate or not. This is obvious in quotation. In fact, when Bakhtin places "soul" in quotation marks, he marks it as a foreign term in his speech. But it can also be elusive allusion or purely a non-conscious summoning of voices past.