- It is forbidden to recite blessings while engaged in another activity. This rule applies not only to Bircas Hamazonbut to all blessings. (Shulchan Aruch OC 183 with Mishnah Berura)
2. Although it is possible to fulfill one’s obligation of Bircas Hamazon by listening to someone else who is saying it — through the principle of “Listening is like speaking” — it is nevertheless better that the person say it himself. This is because it is difficult to concentrate for the duration of the entire blessings, and it is very likely that the listener’s mind will wander to the point that he will not be truly listening to the blessings. (ibid.)
