Same word as sang:

belt out, burst into song, buzz, canary, cantillate, carol, chant, chirp, choir, croon, descant, duet, groan, harmonize, hum, hymn, intone, lift up a voice, line out, lullaby, make melody, mouth, pipe, purr, resound, roar, serenade, shout, singsong, solo, trill, troll, tune, vocalize, wait, warble, whine, whistle, yodel