10. A person who is in [the midst of the first seven days of] mourning may
not leave his home to attend synagogue and say Selichos, with the exception
of the day preceding Rosh HaShanah, when many extra Selichos are recited.
11. A chazan who leads the prayer service during the "Days of Awe" (Rosh
Hashana and Yom Kippur), and similarly, the person who blows the shofar,
should separate themselves from any possible source of impurity for three
days before Rosh HaShanah. They should study the meanings of the words of
the prayers and the liturgical hymns, and the laws of blowing the shofar
(1), to the best of their ability. Similarly, they should study texts of
"mussar" (Torah books providing guidance for perfecting one's personality
and behavior), which arouse a person's mind, and they will then fear G-d's
awesomeness and the grandeur of His glory as He arises to judge the world.
If it is impossible to find a person who is a Torah scholar to blow the
shofar, the person who announces the notes to him should be a Torah scholar
who is well versed in the laws of blowing the shofar. Thus, if a mistake
is made when sounding the shofar, he will know what to do. Similarly, he
will be able to check whether the shofar is kosher or not.
(1) He should also study the deeper esoteric meanings of the prayers and
the notes of the shofar, from the Zohar (Mishna Berura 581:11).