There is an accepted custom to answer “baruch hu u’varuch shemo” (BHUS) to someone’s beracha after the shem haShem is said (unless one is being yotzei with that beracha). During chazaras hashatz one must be careful not to allow that to have him or her miss answering amein. Also, BHUS should not be drawn out, and the chazzan should wait till the BHUS of the tzibbur is finished, as the tzibbur must hear every word of chazaras hashatz, especially the concluding words of the beracha.
Shabbos Bulletin Parshas Emor 5778
About the Author: Lev Seltzer
Lev Seltzer has been a member of Beis Tefillah from just a short time after its founding. He currently manages the BTYA.org website, and can be found every morning in the BTYA "Vasikin Room" where he is the gabbai of the minyon.