90. Answering Barchu

15:7 If there are not nine in the minyan to answer the shaliach tzibbur, he should not recite the Kaddish because all “matters of holiness” require a minyan of one reciting and nine responding. Nevertheless, if one of the ten is saying Shemoneh Esrei, he still counts even though he is unable to respond. This is also the case if up to four people are still saying Shemoneh Esrei, just so long as the majority of the minyan is available to respond. However, if someone is sleeping he must be woken up as a sleeping person does not count in the minyan. (There may be room to be lenient if they try unsuccessfully to rouse the sleeping person – see Biur Halacha on OC 55:6, s.v. “O shehu yashan.”)

15:8 After the shaliach tzibbur says half-Kaddish, he says Barchu. The congregation responds “Baruch Hashem hamevorach l’olam vaed,” which is then repeated by the shaliach tzibbur so as not to exclude himself. (In Barchu he calls on the congregation to bless God. When they do so, so should he!) Some have the custom to say Amen after the shaliach tzibbur but in such a case he does not repeat Amen after them. If the shaliach tzibbur sings Barchu to a tune, which takes a longer than average amount of time, there is a prayer “Yisbarach V’Yishtabach” that the congregation can recite at that time. This prayer is only recited while the shaliach tzibbur is singing a melody; the congregation should be paying attention while he is saying the actual words. If a person didn’t hear the shaliach tzibbur say Barchu but he heard the congregation respond, he may respond with them. (If all one hears is the shaliach tzibbur responding “Baruch Hashem hamevorach” after the congregation, then he should answer “Amen” – see Mishnah Brurah 57:2.)