Scientific pitch notation

The notation makes use of the traditional tone names (A to G) which are followed by numbers showing which octave they are part of.

For standard A440 pitch equal temperament, the system begins at a frequency of 16.35160 Hz, which is assigned the value C0.

The octave 0 of the scientific pitch notation is traditionally called the sub-contra octave, and the tone marked C0 in SPN is written as ,,C or C,, or CCC in traditional systems, such as Helmholtz notation.

Octave 0 of SPN marks the low end of what humans can actually perceive, with the average person being able to hear frequencies no lower than 20 Hz as pitches.

It provides an unambiguous means of identifying a note in terms of textual notation rather than frequency, while at the same time avoiding the transposition conventions that are used in writing the music for instruments such as the clarinet and guitar.

In describing musical pitches, nominally enharmonic spellings can give rise to anomalies where, for example in Pythagorean intonation C♭4 is a lower frequency than B3; but such paradoxes usually do not arise in a scientific context.

With scientific pitch notation, middle C is always C4, and C4 is never any note but middle C. This notation system also avoids the "fussiness" of having to visually distinguish between four and five primes, as well as the typographic issues involved in producing acceptable subscripts or substitutes for them.

C7 is much easier to quickly distinguish visually from C8, than is, for example, c′′′′ from c′′′′′, and the use of simple integers (e.g. C7 and C8) makes subscripts unnecessary altogether.

For an example of truly inaudible frequencies, when the Chandra X-ray Observatory observed the waves of pressure fronts propagating away from a black hole, their one oscillation every 10 million years was described by NASA as corresponding to the B♭ fifty-seven octaves below middle C (B♭−53 or 3.235 fHz).

However, when dealing with earlier music that did not use equal temperament, it is understandably easier to simply refer to notes by their closest modern equivalent, as opposed to specifying the difference using cents every time.

When a piano is tuned to just intonation, C4 refers to the same key on the keyboard, but a slightly different frequency.