octave bass clef

This is a normal bass clef symbol with the number 8 printed above or below. The addition of the number 8 directs the musician to perform the music an octave higher than indicated (with the number 8 printed above) or an octave lower than indicated (with the number 8 printed below). In reality, the symbol merely indicates that the instrument (or voice) that is designated to perform that part actually sounds an octave higher or lower that where it is notated in the normal bass clef.