Singing During Asher Bara

A chashuv Talmid Chochom [who actually inhabited the SAME WOMB that I did a little over a year before I got there and since we were used to sharing space we were later roommates] wrote an article about the custom to sing during the bracha of Asher Bara at a sheva brachos in a book published in the last few days. He felt [based on the Mishna Brura in a different context] that it a problem of hefsek. During a bracha one may not take a break long enough to say the whole bracha which is the case when the tzibbur sings during Asher Bara. [There have been numerous Gedolei Torah who are opposed to this custom]. This is one response written to his very learned article.