C Key: Features and Types

The key is the sign used in musical notation to indicate the height or pitch at which the piece should be interpreted. Located in a specific space or line of the staff, it is the reference point from which the other notes take their name. The most commonly used keys today are the sun key, the F key and the C key.


This sign must always go to the beginning of the work, before the compass and armor. Similarly, the key must go to the beginning of each staff from which the score is composed, before the first bar.

However, any time the record needs it, it can be changed to another. That is, a score can start with C key and mid-piece, as the record of the work goes up, changed to the Sun key (without it being exclusively in the first bar) in order to be able to represent more high-pitched sounds.


This time we will see the characteristics, uses and types of the C key, which is used in musical notation to signal average sounds. Its symbol is represented by two Cs upside down, placed on top of each other, in a stylized version of this letter, which in alphabetical notation indicates the note do: C’ do. On the staff this key will represent note C4 or do4, that is, on the piano is located in the central C.

Likewise, according to the line or space that occupies this key in the staff, the key of C can occupy five positions, giving rise to five key types, Key of C in fifth, Key of C in fourth, Key of C in third, Key of C in second, Key of C in first, although over the years the calves of C in fifth, in the second and in the first have fallen into disuse, they are occasionally used to indicate average sounds. Here’s each one:

C-to-fifth key: Currently deprecated, it gets its name because of its position on the staff, where it is placed on the fifth line from bottom to top (since the lines and spaces of the staff are counted from the bottom up).

In this sense, the fifth line will take the value of C (C), while the immediate lower space will assume the value of Si (B) and the immediate upper space of Re (D), and from then on you will know which name each note receives against this key.

It is now quite strange to find it in sheet music, since its height and notes match the key of F in third. The two keys, both the C in fifth and the Fa in third are also called “baritone key”.

Key of C in fourth: currently in force, is located on the fourth line of the staff, signizing this line with the value of C, so the immediate lower space will take the value of Si (B) and the immediate upper the value of Re (R) and from there advances the rest of notes will take their value. Also known as the “tenor key,” it is used today in music written for bassoon, to signal transitions from some acute cellist notes. It is also used to indicate acute notes of tenor trombone and bombardin.

Key of C in third: also current, it is named for occupying the third line of the staff, causing it to take the value of C, after which the notes of that measure or score will take its value.

In a lower record than the previous key, it is also known as the “contralto key”, although it is also called a “countertenor key”. It is used in musical notation for scores written for mandola, prawn viola, viola and sometimes for high trombone.

Key of C in second: currently deprecated, was located on the second line of the staff (where the Sun key is also located in the second) thus signizing the value of the rest of the notes of that score. It is also known as the “mezzo-soprano key” because in ancient times music used to be written for this choral voice with this key.

Key of C in first: also deprecated, is placed on the first line of the staff, which takes the value of C, thus signizing the value of the notes of the score, according to the place they occupy in reference to this key. For example, the bottom immediate space will take the value of Yes (B) while the top immediate space will take the value of R (B). It is also known as the “soprano key”, for being used in antiquity to write music addressed to this choral voice.

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C Key: Features and Types
Source: Education  
August 22, 2019


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