The term 'low voices' can refer to four different types of vocal ranges: altos, bassi, bassos, and basses. Altos are the highest of the low voices, and are typically sung by female singers. Bassi are slightly lower than altos, and are usually sung by male singers. Bassos are even lower than bassi, and are usually sung by male singers with a deeper range. Basses are the lowest of the low voices, and are typically sung by male singers with the deepest range.