In Parashat Naso, the Mitzvah of Birchat Kohanim, or Duchanen, is presented. The Kohanim have an obligation to deliver a blessing to B’nei Yisrael. The Beit HaLevi asked whether all the Kohanim have to give the blessing, or just one, based on the principle of Shomei’a KeOneh – that hearing something said is tantamount to saying it, so if one Kohen gives the Brachot and the other Kohanim listen, all the Kohanim would be Yotzei their Mitzvah of Birchat Kohanim. The Beit HaLevi explains that the Shomei’a KeOneh principle does not apply in this case because Birchat Kohanim must specifically be recited in a loud voice. Even though through Shomei’a KeOneh, the Kohen would be regarded as saying it, he would not completely fulfill the Mitzvah because he did not recite it in a loud voice. Birchat Kohanim must be said in a loud voice based on the Gemara (Sotah 38a) which explains that when the Pasuk (BeMidbar 6:23) states, “Koh Tevarechu,” “So shall you bless,” it means that Duchanen must be done in a loud voice.
The Ohr Samei’ach posed a fundamental question on the Beit HaLevi’s understanding of Shomei’a KeOneh. According to the understanding of the Beit HaLevi, one should not be able to fulfill the Mitzvot of Kiddush, megillah, and many other mitzvot in the ways that we perform them today. When one hears Kiddush, does he hear it over a cup of wine just like the person making the Kiddush in order to fulfill his Mitzvah? If he did not, then according to the Beit HaLevi’s understanding, one should not fulfill his obligation of Kiddush, because he must carry out all the components of the Mitzvah besides actually saying Kiddush in order to be Mikayem (fulfill) a Mitzvah using Shomei’a KeOneh. The same holds true with Megillat Esther: does one actually have to hear the Megillah out of the Megillah itself in order to be Mikayem the Mitzvah? According to the Beit HaLevi, one would have to do this.
The Ohr Samei’ach explains that Shomei’a KeOneh, in fact, means that when one hears the statement associated with the Mitzvah being recited, all of the things that are being done by the one reciting is utilized by the people who are fulfilling the mitzvah using Shomei’a KeOneh. Thus, when one hears Kiddush being said over a cup of wine, it is regarded as if he is saying Kiddush over a cup.
The Beit HaLevi’s son, Rav Chaim Soloveitchik, rose to his father’s defense of his understanding of Shomeia KeOneh. He said that the Ohr Samei’ach is, of course, correct in his understanding of the principle, but he did not realize the fact that the Beit HaLevi had a different perspective on the Gemara in Sotah. When the Gemara said that Birchat Kohanim must be recited “in a loud voice,” the Beit HaLevi understood it as saying that “in the way one speaks to his friend,” the way the Sifrei also explained this phrase, that all of the people should hear what is being said by the Kohanim. Therefore, one could not use Shomei’a KeOneh to be Mikayem Birchat Kohanim, because it has the special obligation of having to be heard, and using Shomei’a KeOneh cannot make someone else hear one’s theoretical voice.