The Sefer Reshit Chochma (Sha’ar Ha’Kedusha, end of Chapter 15) writes that it is preferable for one to recite Birkat Hamazon out loud, for this improves concentration and this will accustom one to recite Birkat Hamazon in the proper manner amid adequate respect, concentration, and pronunciation of the words as they are supposed to be pronounced. This is especially true regarding Shabbat, festivals, and holidays that reciting Birkat Hamazon aloud will aid in reminding one to insert “Retzeh Ve’Hachalitzenu” and “Ya’aleh Ve’Yavo” which are special texts added to Birkat Hamazon on these days. (See Halacha Berura, Chapter 185, Sha’ar Ha’Tziyun Subchapter 15.)
It is well-known that one’s livelihood and sustenance are contingent on Birkat Hamazon. It is quoted in the name of the righteous and pious Hagaon Harav Yisrael Abuchatzera zt”l (the “Baba Sali”) that one who recites Birkat Hamazon slowly and while reading from a Siddur or a pamphlet shall, without a doubt, merit great sustenance. Indeed, people invest much effort to perform “Segulot” to improve their livelihood; they should certainly heed the primary source of livelihood which is Birkat Hamazon and recite this precious blessing amid much concentration and respect.
Even one who does not recite Birkat Hamazon aloud must at least hear the words he is uttering from his mouth. The righteous author of the Sefer Charedim (Hagaon Harav Elazar Ezkari zt”l, who lived in the times of the Ari z”l) writes (Mitzvot Ha’Teluyot Ba’aretz, end of Chapter 3): “The Mitzvot of prayer, Birkat Hamazon, and Blessings of the Torah which are Torah obligations are likewise contingent on one’s ear; it is a Mitzvah for one’s ears to hear every word he utters. Most Poskim agree that if one’s ears did not hear the words he has uttered, he has not fulfilled his obligation and he must recite the blessing again.”
Maran Rabbeinu Ovadia Yosef Zt”l rebuffs the words of the Sefer Charedim and writes that although one must hear the words of the blessing that one is uttering, nevertheless, if one has not heard the words he has uttered, one still fulfills his obligation. He proceeds to bring sources for this ruling; this is indeed the opinion of most Poskim. (See Responsa Yabia Omer, Volume 4, Chapter 18.)
It is therefore appropriate that we remind the public to recite Birkat Hamazon slowly, pleasantly, and aloud as we have seen many great and pious individuals do. Indeed, we have seen Maran Rabbeinu Ovadia Yosef zt”l, whose time for Torah study was more precious to him than anything else, recite Birkat Hamazon slowly and pleasantly with every word clearly audible and pronounced precisely amid much concentration and peace of mind, as though Birkat Hamazon were the only Mitzvah existent at that moment. Even during the “Harachaman” segment of Birkat Hamazon Maran zt”l recited everything slowly and in a supplicating manner. May we all learn from the actions of our leaders.