Helmholtz pitch notation

Helmholtz pitch notation is a system for naming musical notes of the Western chromatic scale. Developed by the German scientist Hermann von Helmholtz, it uses a combination of upper and lower case letters (A to G),[1] and the sub- and super-prime symbols ( ͵  ′ ) to describe each individual note of the scale. It is one of two formal systems for naming notes in a particular octave, the other being scientific pitch notation.[2]

Helmholtz developed this system in order to accurately define pitches in his classical work on acoustics (1863) translated into English by A. J. Ellis as On the Sensations of Tone (1875).[3][4] He based his notation on the practice of German organ builders for labelling their pipes, itself derived from the old German organ tablature in use from late medieval times until the early 18th century. Helmholz's system is widely used by musicians across Europe and is the one used in the New Grove Dictionary. Once also widely used by scientists and doctors when discussing the scientific and medical aspects of sound in relation to the auditory system, it has now largely been replaced in American and French scientific and medical contexts by scientific pitch notation.[5]

Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik

The Helmholtz scale always starts on the note C and ends at B (C, D, E, F, G, A, B). The note C is shown in different octaves by using upper-case letters for low notes, and lower-case letters for high notes, and adding sub-primes and primes in the following sequence: C͵͵ C c c′ c″ c‴ (or ͵͵C ͵C C c c′ c″ c‴) and so on.

Middle C is designated c′, therefore the octave upwards from middle C is c′–b′.

Each octave may also be given a name based on the "German method" (see below). For example, the octave from c′b′ is called the one-line octave[2] or (less common) once-accented octave.[6] Correspondingly, the notes in the octave may be called one-lined C, etc.

This diagram gives examples of the lowest and highest note in each octave, giving their name in the Helmholtz system, and the "German method" of octave nomenclature. (The octave below the contra octave is known as the sub-contra octave).