The term hazzan may be borrowed from the Assyrian word "Hazanu." In the Talmud the term is used to denote the "overseer": (1) of a city; (2) of a court of justice; (3) of the Temple; (4) of the synagogue. In regards to a hazzan's duties in the synagogue, the Talmud notes that he brought out the rolls of the Torah, opened them at the appointed readings for the week, and put them away again, with trumpet-blasts he announced the beginnings of Sabbaths and holy days from the roof of the synagogue, he attended to the lamps of the synagogue, he accompanied the pilgrims that brought the firstlings to the sanctuary of Jerusalem. His place was in the middle of the synagogue, on the wooden "bimah", and sometimes would read aloud from the Torah. A passage in the Jerusalem Talmud (Ber. ix. 12d), implies the hazzan also led the prayers in the synagogue.
During the early medieval era, the duties of reading from the Torah and of reciting the prayers were included, as a rule, among the functions of the Hazzan. The blowing of the shofar was also one of his duties, as may be seen from a responsum of Rabbi Solomon ben Adret (No. 300). He acted sometimes as secretary to the congregation. He was assisted, especially on festival days, by a chorus ("meshorerim," singers). This institution was afterward developed in Poland and Germany, where a singer stood on each side of the precentor and accompanied him, sometimes in high, sometimes in low, tones, at intervals singing independently.
The office of hazzan increased in importance with the centuries. As public worship was developed in the geonic period, and as the knowledge of the Hebrew language declined, singing gradually superseded the didactic and hortatory element in the worship in the synagogue.
Even in the oldest times the chief qualifications demanded of the hazzan, in addition to knowledge of Biblical and liturgical literature, were a pleasant voice and an artistic delivery; for the sake of these, many faults were willingly overlooked. The hazzan was required to possess a pleasing appearance, to be married, and to wear a flowing beard. Sometimes, according to Isaac of Vienna (13th cent.), a young hazzan having only a slight growth of beard was tolerated. Maimonides decided that the hazzan who recited the prayers on an ordinary Sabbath and on week-days need not possess an appearance pleasing to everybody; he might even have a reputation not wholly spotless, provided he was living at the time of his appointment a life morally free from reproach.
But all these moderations of the rule disappeared on holidays; then an especially worthy hazzan was demanded, one whose life was absolutely irreproachable, who was generally popular, and who was endowed with an expressive delivery. Even a person who had once appealed to a non-Jewish court, instead of to a Jewish court, in a disputed question could not act as hazzan on those days, unless he had previously done penance (Shulkhan Arukh, Orah Hayyim, 581).
In the early Middle Ages the office of hazzan seems to have been held in high esteem, for scholars like Rabbi Eliezer ben Meshullam and Rabbi Meïr acted as the leaders in prayer. As late as the end of the fourteenth century Jacob Möln ha-Levi (Maharil), at the express desire of the congregation, read the prayer on special festivals, such as New-Year, the Day of Atonement, the eve of the 9th of Av, Hosha'na Rabbah, and Shemini 'Atzeret. In Spain, however, even at the beginning of the fourteenth century, Jews of the better families seem no longer to have adopted this calling, and the position of the hazzan in Spain was a source of surprise and grief to the German Asher ben Jehiel. No other communal official of the Middle Ages occasioned so much and so frequent complaint as the hazzan. As early as the ninth century complaint was made that the hazzanim changed the text of the regular prayers. In connection with the piyyutim, some hazzanim introduced melodies taken from non-Jewish sources, which in some cases was a controversial move.
Against these changes Alfasi (Responsa, No. 281), the "Book of the Pious" (ed. Basel, Nos. 238, 768), Maimonides ("Moreh," i. 59), Asher ben Jehiel ("Besamim Rosh," iv 22), and others protested in vain. The earlier Jewish melodies, not having been written down, were changed by the hazzanim, consciously or unconsciously, in accordance with their individual tastes, which were often very poor. Their vanity also led them to prolong single notes and to insert interludes of song. Thereby the prayers were greatly lengthened. Complaints on this score were of no avail. Hazzanim were continually censured for vanity. According to Rabbi Asher ben Jehiel (ib.), they sang only what was most likely to win applause.
There are many rule relating to how a cantor should lead services, but the idea of a cantor as a paid professional does not exist in classical rabbinic Jewish sources. The Jewish prayer services have their own entry; the prayers in these services are collected in a prayerbook known as the siddur.
The person leading the congregation in public prayers is called the shaliach tzibbur (Hebrew for "emissary of the congregation"). Traditional Jewish law restricts the shaliach tzibbur to be males over the age of 13; the non-Orthodox Jewish movements allow women over the age of 12 to have this role as well.
In theory, any lay person can be a shaliach tzibuur; most synagogue attending Jews serve in this role at least once in their life. In practice, those with the best voice and the most knowledge of the prayers serve much more often, and the role of cantors as a respected full-time profession has become a reality in recent centuries.
In an interesting turn of events, the United States government recognized Cantors as the first Jewish clergy, even before rabbis were recognized.
The period between the two World Wars is often referred to as the "golden age" of hazzanut (cantors). Some of the greats include Abraham Davis, Moshe Koussevitzky, Zavel Kwartin (1874-1953), Jan Peerce, Joseph Yossele Rosenblatt 1880-1933), Gershon Sirota (1874-1943), and Laibale Waldman.