Why 4? Easy First Tenor ( hits the high notes) Second tenor little bit lower notes Baritone ( or first bass ) Bass ( or second bass ) the low notes he rumbles. They are not always in this order as they cross over frequently. The ranges overlap. In general the notes will form a 4 note chord. I think that many of the popular male singers were baritones - Bing Crosby for instance I used to sing second base - but age has beat me - stopped singin in the church choir this year. Bob Anibal