: Singing is the act of producing musical sounds with the voice, which is often contrasted with speech. Contrary to common thought, air isn't expelled with the diaphragm, but is inhaled using the diaphragm and exhaled or expelled, using the abdominal and lower pelvic muscles, as with ordinary breathing. The pitch is altered with the vocal cords. With the lips closed, this is called humming. A piece of music with a singing part, either a cappella (without accompaniment) or accompanied, is called… (More on Vocals)