a bass is the lowest male singing voice.
Bass is the name of a very low male singing voice.
The lowest singing voice is the male voice called bass.
The lowest normally recognised is the 'contralto'.
The lowest female voice is called contralto.
Bass
Contalto
Bass.
The lowest female voice is the Contralto; also considered the rarest in occurrance.
Bass Baritone
Baritone
Bass is below Baritone and the lowest male voice range