In musical notation it is known as a key to the sign used to indicate at the beginning of the score the tone or height at which the piece should be performed. Its location on a staff line will cause the staff to take the value of the key, causing the other notes to take their name according to this reference.
Currently the most well-known keys are the sun key, the C key and the F key. These must be placed at the beginning of the score, before the compass and armor. It should also be written at the beginning of each of the staves that make up the part. Its appearance does not indicate that it cannot be changed at any time (not necessarily at the beginning of staff) of the part, which will be done if the registration requires it.
This time we will describe the key of F, as well as its uses and types. In this sense, we will begin by describing its symbol, which originates from a stylized form of the letter F, which is used in alphabetical notation to designate the note fa: F. f. On the staff it places the note fa3, that is, on the piano is located three white keys from the central C.
It is also accompanied by two points, one on top of the other (as if it were two points in a row: ) which are located to your right, delimiting the line where the key is located, so that one will go in the immediate upper space, while the other will the immediate lower space. This key is used to represent bass sounds.
Within this key there are several types, being able to find keys of F in fourth, third and fifth, although in the present time the last two have fallen into disuse. Below we will describe each of these types, as well as their uses:
Key of F in fourth: currently in force, it is located on the fourth line of the staff, counting from the bottom up (because in musical notation the lines and spaces of the staff are counted in this way).
This key designates this line with the value of F, marking reference so that the notes of the rest of the score governed by it take its name. Today it is mainly used for the most serious recorded instruments, such as cello, double bass (rubbed string) as well as tuba, trombone (metal wind) and bassoon, contraphage (wood wind).
It can also be obtained in sheet music written for harp or piano, as well as for percussion. This musical sign is the one that allows to represent on the staff the most bass sounds.
Key of F in third: today in disuse, it gets its name from the place of its location, being on the third line of the staff, which takes the value of C, signizing the rest of the notes of the score governed by this key. It is also known as the “baritone key” because it was headed in antiquity the scores written for this vocal voice. It is currently used only to allow interpreters to transport non-transposing instruments.
Key of F en quinta: also deprecated, it is named because it is located on the fifth line of the staff, which takes the value of F, signizing the rest of the notes, which will take their name according to their location taking as reference the location of this key. That is, the immediate space below it will take the value of my (E) while the immediate upper space will be for sun (G). This key is also known as the “subwoofer key”.
In ancient times it was used by composers such as Bach, who includes it in the piece Musical Offering. The musical notes governed by this key coincide in name and position with those signified by the sun key in the second, only that they respond to a more serious two-octave tesssitura.
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Phoneia.com (August 22, 2019). Key of F: Features and types. Recovered from https://phoneia.com/en/curiosities/key-of-f-features-and-types/