שולחן ערוך אורח חיים · סימן נ״ז

English

Laws of Bar'khu and its responses comprising 2 sections: The prayer leader says: "Bar'khu et Adonai ha-mevorach", and they [the congregation] answer after him: "Barukh Adonai ha-mevorach l'olam va'ed", then the prayer leader returns and says: "Barukh Adonai ha-mevorach l'olam va'ed". Rem"a: And some have the custom that the prayer leader lengthens "Bar'khu", and the congregation say "Yitbarakh v'yishtabach..." while he is extending "Bar'khu" (Tur).

English

A place where the practice is to shout at/rebuke their fellows between Kaddish/ Bar'khu and Yotzer Ohr or to speak regarding the needs of the public... they are mistaken. (See above, at the end of Siman 54)