ASBI Pocket Beit Midrash, Aruch HaShulchan, Rosh Hashanah 585:5

The one who blows shofar makes the blessing "Blessed....who sanctified us with His Commandments and commanded us to hear the sound of the shofar" for the mitzvah is in the hearing. And if one blows and does not hear, then he has not fulfilled his obligation whatsoever. And then he recites a "SheHechiyanu" blessing and the congregation responds "amen" to the two blessings. And one should be careful not to say "Baruch Hu U'Varuch Shemo" for that would be an interruption in the blessing. And even if the shofar blower has already fulfilled his obligation, he should make these blessings on behalf of those who hear him. But it would be better if the listeners make teh blessings and not the blower since he has already fulfilled his obligation - especially the "she'hechiyanu" blessing. But this is not the common practice. And nonetheless if one blows shofar for an individual, for example someone who is sick, it is best if the listener makes the blessings (cf Magen Avraham 3). And in particular if the blower is blowing on behalf of a woman or several women, who are personally exempt from the mitzvah of shofar, since it is a "positive time-bound mitzvah" but they have obligated themselves, it is certainly appropriate that they make the blessings for themselves rather than have the shofar blower make the blessings unless he too has not yet fulfilled his obligation.