The synagogue officer who chants much of the Yom Kippur liturgy is the cantor.
In Jewish usage, cantor is the English equivalent of hazzan or chazzan. The cantor leads congregational prayer, sings or chants the service, and uses traditional melodies known as nusach. On Yom Kippur, the role is especially prominent because the services are unusually long and include distinctive musical passages, penitential prayers, and highly recognizable moments such as Kol Nidre.
The cantor is not simply a solo performer. The position combines musical skill, Hebrew pronunciation, knowledge of liturgical customs, and responsibility for guiding the congregation through changes in text and melody. In some settings, the cantor also teaches, conducts choirs, and provides pastoral support.
Strictly speaking, any person leading public prayer may be called a shaliach tzibbur, or “messenger of the congregation.” Thus a rabbi, layperson, or rotating congregant may lead a service. But when a question asks for the synagogue officer specially associated with chanting the liturgy, cantor is the standard answer.