A choir section is composed of several different vocal parts. The BASS part is the lowest part, followed by the ALTO part, which is slightly higher than the BASS. Altos are a group of singers who sing in the ALTO range. An APSE is a semicircular recess in a church or other building, often used for a choir. Tenors are a group of singers who sing in the tenor range, which is higher than the ALTO range. PSALM is a song or hymn of praise from the Bible. Together, these parts make up a choir section.