The sh'liach tzibur means the "messenger" or the "envoy" of the community. The Hebrew term is sometimes shortened to the word "shatz."
The term sh'liach tzibur refers to the designation of the person who in public synagogue worship officiates as both cantor and leader. The shatz's main function is to lead the congregants in communal worship.
According to the Shulchan Aruch (the 16th-century code of Jewish law), the sh'liach tzibur must demonstrate humility, acceptability to the congregation, knowledge of the rules of prayer and the proper pronunciation of the Hebrew text, an agreeable voice, proper dress, and a beard. (The beard may be waived except for the High Holidays.) For all but a few preparatory prayers and hymns, the sh'liach tzibur can only be a male of Bar Mitzvah status. (Encyclopedia Judaica)
The sh'liach tzibur referred to in the Talmud was an individual appointed to supervise community affairs. He officiated at morning, afternoon, and evening services every day, acting on behalf of the congregants to fulfill their worship obligations. Another term for sh'liach tzibur is chazzan which is found in the Mishnah. There, it refers to three different occupations. In the first chapter of Shabbat. Mishnah 3 the commentary of Obadiah Bartinurah explains the term chazzan as a teacher of children. In Makkot 3:12 and in Tamid 5:3, he explains that the term refers to an attendant or messenger of the court. In the Sefer Ha-Arukh, under the heading chazzan, the term is explained as originating in the Hebrew verb, hozeh, "sees." From here, we understand that the sh'liach tzibur or the chazzan must be able to see how to read the Torah. (The Cantor's Manual of Jewish Law, p. 20.)
A sh'liach tzibur who intensifies the service so that all may hear his sweet voice joyously give thanks to God will be blessed for it if he prays with humility and stands with awe. Where his intention is only to let himself be heard, however, his joy being pride in his voice lone, this is disgraceful....He who unduly prolongs the service acts wrongful and puts an excessive burden upon the congregation....He whom the Holy One Blessed Be He has endowed with a pleasant voice, let him sing to God at festivals in honor of the fulfillment of a mitzvah in preference to secular festivities. (The Cantor's Manual of Jewish Law.)
Chazzanut has become a skill, a technical performance, an impersonal affair. As a result, the sounds that come out of the chazzan evoke no participation. They enter the ears; they do not touch the hearts. The right Hebrew word for cantor is ba'al tefillah, master of prayer. The mission of a cantor is to lead in prayer. He does not stand before the Ark as an artist in isolation, trying to demonstrate his skill or to display vocal feats. He stands before the Ark not as an individual, but with a congregation. He must identify himself with the congregation. His task is to represent as well as to inspire a community. Within the synagogue, music is not an end in itself, but a means of religious experience. Its function is to help us to live through a moment of confrontation with the presence of God; to expose ourselves to God in praise, in self-scrutiny, and in hope. ("The Vocation of the Cantor," Abraham Joshua Heschel.)
Those who chant prayers borrowed from the melodies of the Moslems should be removed from office. (Alfasi)
Chazzanim are specifically forbidden to sing any song in Arabic, even at a party or social gathering. (Sha'arei Teshuvah #152)
Music in general...is forbidden, except when it belongs to prayer which moves the soul either to joy or sorrow....Moreover, there is no difference between the singing of Hebrew or of Arabic words. Permission or prohibition depends exclusively upon the content of the words. (Maimonides)