Tenor clef
The C clef on the fourth line.
What it means
The tenor clef is the C clef on the fourth line, that is, the second from the top: there lies middle c. Alongside the alto clef, it is the only C clef that has remained in use today. It covers the range between the bass and treble registers and serves above all to avoid ledger lines when a low instrument plays for some time in a high register.
In the notation
The sign is the same as with the alto and soprano clefs; only its position on the staff distinguishes them. The meeting point of the two curves lies here on the fourth line. A note that would need several ledger lines above the staff in the bass clef sits here comfortably within the lines. The change is indicated in the notated text at the relevant point by the new sign, usually in smaller form, and likewise back again.
Musical use
Cello, bassoon, and trombone notate in a high register in the tenor clef and return afterward to the bass clef; if the part rises still further, the treble clef follows. Much the same holds for the double bass, though taking octave transposition into account. In vocal music before the nineteenth century, the tenor voice regularly carried this clef; today it is notated in the treble clef with a lowered octave sign, or, in sounding notation, in the bass clef.
The tenor clef is to be distinguished from the alto clef solely by the line — the same sign set one position higher turns the one into the other.
The tenor clef is used today with cello, bassoon, and trombone for higher registers.
Performance practice
Learn this clef too by anchor notes rather than by converting from the bass clef; the seemingly convenient shift becomes a permanent brake. Mark every clef change in your part before playing through for the first time, and practise the affected bars separately — the errors almost always arise in the bar after the change, not in it itself. If you are reading between several clefs, practise them in separate short units.