Jewish music is used all across the planet in their synagogues, and is used in their direct prayers. It can be sung as unaccompanied vocals, or Biblical cantillation (Hebrew cantillation), which is when reading from the holy text in religion is sang out loud. All of these are under the eyes of the Chazan (cantor).
A spiritual and religious leader in Jewish culture. They are consulted for advice during congregations. They can be asked about religious, social, or advice in Jewish law.
There is a sharp difference in the way people see a Rabbi, and Chazan, Rabbis are often seen as spiritual leaders, Chazans are the musical leaders during mass.