כל שאינו מחוייב בדבר אינו מוציא אחרים ידי חובתן:

Anyone not obligated in something cannot enable another to fulfil that obligation.

A deaf person, an imbecile and a minor are exempt. And even if the deaf person is able to speak, the fact that he cannot hear means he has no obligation. Rema: However, a dumb person is able to enable others to fulfil their obligation (Beit Yosef).

A woman is exempt [from the mitzva of shofar] as it is a positive time-bound mitzva.

An Androgynous enables others of their gender to fulfil their obligation, but a Tumtum is unable to do even this.

Someone who is part servant and part free can't even enable themselves to fulfil the obligation. They require a freeman to blow for them.

Even though women and exempt, they are permitted to blow. So too, even after a man fulfilled his obligation, he is still able to blow for their obligation. However, [in these cases,] they should not make the blessing, nor should he make the blessing for them. Rema: And [our] custom is that women make blessings on positive time-bound mitzvot, so here too they would make the blessing for themselves. However, others should not bless for them if they have already fulfilled their obligation and are only blowing for the sake of women. However, if they are blowing [for women and] a man who is obligated, they make a blessing on his account, even though they already fulfilled their obligation, as has been explained in Chapter 585, subsection 2 in the first gloss.

If somebody swears off benefiting from his friend, that friend is permitted to sound a shofar for him to fulfill the obligation. This is only the case when he sounds the shofar unprompted to fulfill his obligation. But if the swearer says "Blow to fulfill my obligation," this is forbidden. Rema: If he says "His soundings are konam to me," it is always forbidden (Ra"n).

Someone who is engaged in blowing a shofar in order to practice doesn't fulfil his obligation. Similarly, someone who hears shofar from someone such a person doesn't fulfil his obligation. Similarly, someone who is blowing the shofar to make music and doesn't intend for the mitzva of blowing the shofar doesn't fulfil his obligation. If the listener intends to fulfil the mitzva but the blower doesn't have intent for him or if blower has intent for him but the listener does not; he doesn't fulfil his obligation until the two of them have intent, the listener and the blower.

If somebody blows the shofar with the intention of fulfilling the obligation of every listener, and somebody hears it and has the intention to fulfill their obligation, even if the blower is not intending for this specific person who hears his blasts and doesn't know them, they fulfill their obligation, given that he had the intention to fulfill the obligation of everybody who heard him. Therefore, if somebody was walking on the street or sitting at home and heard the communal blasts, they fulfill their obligation if they have the intention to fulfill their obligation because the communal blower has the intention to fulfill the members of the community's obligations.