I'm always exhausted at the end of 15 hours of Kol Nidre/Yom Kippur services, but it's almost embarrassing to admit it when I compare the small job I have to do with the incredible task that our cantor takes on. Not only does she have to sing almost constantly through these services (much more than any Christian cantor I've ever heard, btw) while fasting, but ultimately her charge is to lead her congregation in their spiritual journey through prayer and to channel, you know, a few thousand years of Jewish music and tradition. There's nothing quite like listening to a good Jewish cantor to remind you that singing should never be just about hearing yourself sing.
A couple years ago I heard Cantor Roslyn Barak from Temple Emanu-el sing and speak a bit. She quoted Abraham Heschel's essay titled "The Vocation of the Cantor" (from The Insecurity of Freedom), in which he explores what the cantor's role should be in the life of his or her congregation, and how music achieves that goal. Much of what she said I found relevant even to non-liturgical singing, and she was kind enough to send me a copy of the essay afterwards. Some snippets from Heschel's piece are below for you to chew on. Kippot off to all you Chazzanim out there: you have my respect.
One must realize the difficulties of the Cantor. The call to prayer often falls against an iron wall. The congregation is not always open and ready to worship. The Cantor has to pierce the armor of indifference. He has to fight for a response. He has to conquer them in order to speak for them. Often he must first be one who awakens those who slumber.
To sing means to sense and affirm that the spirit is real and that its glory is present. In singing we perceive what is otherwise beyond perceiving. Song, and particularly liturgical song, is not only an act of expression but also a way of bringing down the spirit from heaven to earth.
Words die of routine. The Cantor's task is to bring them to life. A Cantor is a person who knows the secret of the resurrection of the words.
Song is the most intimate expression of man. In no other way does man reveal himself so completely as in the way he sings. For the voice of a person, particularly when in song, is the soul in its full nakedness. When we sing, we utter and confess all our thoughts.