The purpose of the alto pitch vocal.

When listening to a song you will notice changes in the vocal pitch throughout the song. The term alto is the high tone. Just like rhythm, tempo or other measures of music, vocals have measures as well. In a solo piece, which is one singer on stage, an alto usually sings at a very high pitch sound and sings very high notes. Such terms are used to segment music in categories from low, medium and high pitch sounds. This keeps things organized so that the musician or singer can comprehend the levels at which they are to deliver the sounds. The purpose of the alto it to deliver a high pitch sound when singing.