0 a sign on a stave (= the five lines on which music is written) that shows that the notes are below middle C (= the C near the middle of a piano keyboard) -- 低音谱号
The use of alto clef is usually confined to orchestral first trombone parts, with the second trombone part written in tenor clef and the third (bass) part in bass clef.
The first four movements are played in standard tuning, although due to the number of low notes, the last movement is notated with an additional bass clef.
As the alto trombone declined in popularity during the 19th century, this practice was gradually abandoned and first trombone parts came to be notated in the tenor or bass clef.
Romberg is responsible for simplifying cello notation to only three clefs, the bass clef, the tenor clef and the treble clef.
Some composers notated it in the bass clef, when the lower register was persistently used, and historically several other options were employed.
Its music is written in the bass clef.
The music is notated on three systems, with the melody being noted on the upper system with the bass clef.
Consequently, when its music is written in treble clef, the tuba is a transposing instrument, but not when the music is in bass clef.
