Part II: Is there an obligation to hear shofar in Elul?
In Part I , most halakhic sources indicate that shofar in Elul is a custom, not on the level of a rabbinic obligation. Even though it is connected to a takana, a rabbinic enactment, the language generally used is that of minhag – custom. Likewise, Magen Avraham explains that the reason we don’t blow the shofar the day before Rosh HaShana is to differentiate between these voluntary shofar blasts and the Torah mitzvah on Rosh HaShana, clearly stating that shofar in Elul is voluntary, and not a rabbinic obligation.
“The custom of Israel is Torah”
Nevertheless, in some cases minhag does take on a sense of obligation, as the oft-quoted Tosafot states: “The custom of Israel is Torah.” Indeed, later halakhic authorities discuss the nature of the obligation (chiyyuv), not the “practice” (nohag) – with some referencing the original takana and others the minhag. Based on a creative reading of the aforementioned Magen Avraham, Rav Tzvi Pesach Frank raises the possibility that individuals are obligated to hear shofar in Elul.
Tzitz Eliezer rejects this possibility and brings several arguments to prove that the obligation is communal. His first and most persuasive proof is not based on textual analysis, but rather on the way the minhag is observed today – individuals who are not able to pray with a minyan in Elul do not search for a way to hear the shofar. He continues to note the rule that rabbinic enactments follow the rules of the original concept. In this case we are not following the rules of Rosh HaShana shofar blowing, which is not the source of the enactment, but rather Israel’s Rosh Chodesh Elul shofar blasts in the desert. As those were “in the camp,” these are in the community.
Revivot Efraim analyzes the question based on Tur’s description of the minhag. If the reason for shofar in Elul is to commemorate the original shofar blasts in the desert and to “befuddle the Satan” then it is a communal requirement; if teshuva is the end goal perhaps it is individual. Ultimately, he writes that few halakhic authorities maintain there is an individual requirement, but many maintain it is a communal enactment, including Rav Tzvi Pesach Frank, who accepted Tzitz Eliezer’s opinion.
This also explains why women who are careful to hear shofar on Rosh HaShana don’t make similar efforts in Elul. If this is a communal obligation then there is less reason for individuals who don’t attend minyan (communal prayers with a quorum of ten men) to seek out private shofar blasts, although some pious individuals may do so, as we noted in Part I.
 As we saw Tur (ibid) begins by discussing the “takana” from Pirkei d’Rabbi Eliezer, and then continues with the language that this is the “minhag” in Ashkenaz.
 If he believed there was a rabbinic obligation it seems he should have used the differentiation between “rabbinic and Torah blasts” and not “voluntary and obligatory.”
He adds that someone who is practicing blowing shofar is allowed to do so at home according to this reason, but not according to those who claim we refrain from blowing the shofar to confuse the Satan. Mishna Berura says even in this case one may practice in a closed room. (ibid 24, based on Eliya Rabba and Sefer HaAmrakhel)
 This is based on a question in Sha’ashueu Tzvi and Tzitz Eliezer XII 48. In the note above we saw that Magen Avraham raises the possibility an individual is prohibited from practicing shofar at home on erev Rosh HaShana – he suggests that if there was only a communal obligation then the directive not to blast shofar on erev Rosh HaShana would also be communal, so an individual would be allowed to blast shofar.
 There is a halakhic principle that when a halakha is in doubt the accepted practice can be learned from what people are already doing – “puk chazei ma ama davar,” “go out and see what the people do” – because “even if they themselves are not prophets they are children of prophets.”
 Similarly, the Tur explains the reason for the Elul blasts with the verse “When a shofar blows in the city” – also a communal space.
 In this case the Satan seems to be the external, prosecutorial concept.