# What is the origin of the notation A4, B3, F5, etc. (i.e. <letter><number>)

Long before I started to play an instrument I used to tune my young son's guitar for him using a device which told me how close the strings were to the correct notes of E2, A2, D3, G3, B3 and E4.

When was this notation invented and where does it come from?

• The notation is called "Scientific pitch notation" Mar 4, 2021 at 16:08
• I assume the question is about the scheme <tone name><octave number>? This is the only notation i can detect. at least. (This could be more clearly stated). Then the related question concerning alternatives is here. Mar 4, 2021 at 16:37
• The question isn't about the origin of 440Hz as the standard A4. It's about the origin of scientific pitch notation. Mar 4, 2021 at 17:17
• I just checked on meta and it appears that "When someone wants to close your question as a duplicate even when it's not, you should immediately edit (not re-post) the question to clarify that it is not." meta.stackexchange.com/questions/194476/… Mar 4, 2021 at 20:54

Scientific pitch was proposed in 1939 and adopted internationally in 1955.

With changes in concert pitch and the widespread adoption of A440 as a musical standard, new scientific frequency tables were published by the Acoustical Society of America in 1939, and adopted by the International Organization for Standardization in 1955. C0, which was exactly 16 Hz under the scientific pitch standard, is now 16.352 Hz under the current international standard system (SOURCE: Source contains some other interesting tidbits of SPN's prehistory.)

Here is the abstract from the 1939 article proposing SCN.

Abstract: Fletcher [see below] has proposed the use of a logarithmic frequency scale such that the frequency level equals the number of octaves, tones, or semitones that a given frequency lies above a reference frequency of 16.35 cycles/sec., a frequency which is in the neighborhood of that producing the lowest pitch audible to the average ear. The merits of such a scale are here briefly discussed, and arguments are presented in favor of this choice of reference frequency. Using frequency level as a count of octaves or semitones from the reference C0, a rational system of subscript notation follows logically for the designation of musical tones without the aid of staff notation. In addition to certain conveniences such as uniformity of characters and simplicity of subscripts (the eight C's of the piano, for example, are represented by C1 to C8) this method shows by a glance at the subscript the frequency level of a given tone counted in octaves from the reference C0=16.352cycles/sec. From middle C4, frequency 261.63 cycles/sec., the interval is four octaves to the reference frequency, so that below C4 there are roughly four octaves of audible sound. Various subdivisions of the octave are considered in the light of their ease of calculation and significance, and the semitone, including its hundredth part, the cent, is shown to be particularly suitable. Consequently, for general use in which a unit smaller than the octave is necessary it is recommended that frequency level counted in semitones from the reference frequency be employed. (https://asa.scitation.org/doi/abs/10.1121/1.1916017)

H. Fletcher, J. Acous. Soc. Am. 6, 59-69 (1934). (https://asa.scitation.org/doi/pdf/10.1121/1.1902141)

The current status of the standard can be found at https://www.iso.org/standard/3601.html.

However, there is no official standard for pitch notation, although, as shown in the excerpt above, scientific pitch uses scientific pitch notation in its adoption.

• Do you have a link to a modern standard? If I try to search for middle C being C4 all I find is links to music theory websites and wikipedia, not a single official standards document on the web. Oct 13, 2023 at 20:12
• And what is the ISO standard you refer to in 1955? The only one I can find is ISO 16 in 1975, which relates to the pitch of the A above middle C, and does not give it a number. Oct 13, 2023 at 20:26
• But ISO standard 16 just says the A above middle C is 440Hz. It doesn't say anything about octave numbering. As far as I can find anywhere on the web officially there is no international standard for C4. "Scientific pitch notation" or "International pitch notation" is really just "USA acoustical society standard". So when the OP asks about his guitar being E2, he might be told E1 in Japan or Germany, or by an Ableton, FL Studio, Bitwig, Yamaha, Logic, or Cubase user. Oct 14, 2023 at 7:23
• Yes, but your answer says "Scientific pitch notation was proposed in 1939 and adopted internationally in 1955.", which is incorrect. I can't see anywhere that it was adopted internationally. Only 440hz was adopted. Oct 14, 2023 at 7:29
• @Richard Okay, I see the problem. When I originally wrote this answer, it looks like I confused Scientific Pitch with Scientific Pitch Notation. There is no internationally recognized standard for pitch notation. Oct 14, 2023 at 7:33