A text summary of the clickable map above, meant for web-crawlers and other automatic tools:
human voice is basis of human speech
human voice created by vibration of vocal cords
human voice creates sound
human voice creates Early song
human voice creates speech
human voice creates tone
human voice creates pitch
human voice creates notes
human voice creates musical sound
human voice creates music
human voice creates Early Music
human voice creates model for Early instruments
human voice used to create Early Music
human voice used to create a cappella