Q. Should someone who went to the bathroom during Mussaf on Rosh Hashana say asher yotzar, or not be mafsik (interrupt) during tekias shofar and wait until after the last tekia? What about if someone has a condition that he has to go out several times. does it make a difference?
A. P’nei Yehoshua (Rosh Hashana 34b) rules that since all the voices of the shofar are essential, they are considered as one single mitzva. They are similar to hallel and the reading of the megila, and one should not be mafsik to recite asher yotzar while reciting them.
However, other Poskim are lenient. (Minchas Yitzchok 3: 44 – 4: 47, Shevet Halevi 5: 66, Tzitz Eliezer 11: 45, Piskei Teshuvos 592: 4, and others).
Horav Shlomo Miller’s Shlit’a opinion is that one can interrupt to recite this brocho after hearing the complete first thirty voices of the shofar. It also does not make any difference how many times it is recited.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a