Editing Musical note (section)

=== Distinguishing pitches of different octaves ===
Two pitches that are any number of [[octave]]s apart (i.e. their [[fundamental frequency|fundamental frequencies]] are in a ratio equal to a [[power of two]]) are perceived as very similar. Because of that, all notes with these kinds of relations can be grouped under the same [[pitch class]] and are often given the same name.

The top note of a [[musical scale]] is the bottom note's second [[harmonic]] and has double the bottom note's frequency. Because both notes belong to the same pitch class, they are often called by the same name. That top note may also be referred to as the "[[octave]]" of the bottom note, since an octave is the [[Interval (music)|interval]] between a note and another with double frequency.

==== Scientific versus Helmholtz pitch notation ====
{{See also|Piano key frequencies}}

Two nomenclature systems for differentiating pitches that have the same pitch class but which fall into different octaves are:

# [[Helmholtz pitch notation]], which distinguishes octaves using [[prime symbol]]s and [[letter case]] of the pitch class letter.
#* The octave below [[middle C|tenor '''C''']] is called the "great" octave. Notes in it and are written as [[upper case]] letters.
#** The next lower octave is named "contra". Notes in it include a prime symbol below the note's letter.
#** Names of subsequent lower octaves are preceded with "sub". Notes in each include an additional prime symbol below the note's letter.
#* The octave starting at tenor '''C''' is called the "small" octave. Notes in it are written as [[lower case]] letters, so [[middle C|tenor '''C''']] itself is written '''c''' in [[Helmholtz pitch notation|Helmholtz notation]].
#** The next higher octave is called "one-lined". Notes in it include a prime symbol above the note's letter, so middle '''C''' is written '''c′'''.
#** Names of subsequently higher octaves use higher numbers before the "lined". Notes in each include an addition prime symbol above the note's letter.
# [[Scientific pitch notation]], where a pitch class letter ('''C''', '''D''', '''E''', '''F''', '''G''', '''A''', '''B''') is followed by a subscript [[Arabic numerals|Arabic numeral]] designating a specific octave.
#* Middle '''C''' is named '''C'''<sub>4</sub> and is the start of the 4th octave.
#** Higher octaves use successively higher number and lower octaves use successively lower numbers.
#** The lowest note on most pianos is '''A'''<sub>0</sub>, the highest is '''C'''<sub>8</sub>.

For instance, the standard [[A440 (pitch standard)|440&nbsp;Hz]] tuning pitch is named '''A'''<sub>4</sub> in scientific notation and instead named '''a′''' in Helmholtz notation.

Meanwhile, the [[electronic musical instrument]] standard called [[MIDI]] doesn't specifically designate pitch classes, but instead names pitches by counting from its lowest note: number&nbsp;0 {{nobr|('''C'''<sub>−1</sub> ≈ 8.1758 Hz)}}; up chromatically to its highest: number 127 {{nobr|('''G'''<sub>9</sub> ≈ 12,544 Hz).}} (Although the [[MIDI]] ''standard'' is clear, the octaves actually played by any one [[MIDI]] device don't necessarily match the octaves shown below, especially in older instruments.)

:{| class="wikitable" style="text-align: center"
|+ Comparison of pitch naming conventions over different octaves
!colspan="2"| [[Helmholtz pitch notation|Helmholtz]] notation
!rowspan="2"| [[Scientific pitch notation|'Scientific']]<br/>note<br/>names
!rowspan="2"| [[MIDI]]<br/>note<br/>numbers
!rowspan="2"| Frequency of<br/>that octave's [[A (musical note)|'''A''']]<br/>(in [[Hertz]])
|-
! octave name || note names 
|-
|style="text-align:left"| &nbsp; sub-subcontra &nbsp;
| '''C„‚''' – '''B„‚''' || '''C'''{{sub|−1}} – '''B'''{{sub|−1}} || {{0}}0 – 11
|style="text-align:right"| 13.75 &emsp;
|-
|style="text-align:left"| &nbsp; sub-contra
| '''C„''' – '''B„''' || '''C'''{{sub|0}} – '''B'''{{sub|0}} || 12 – 23
|style="text-align:right"| 27.5{{0}} &emsp;
|-
|style="text-align:left"| &nbsp; contra
| '''C‚''' – '''B‚''' || '''C'''{{sub|1}} – '''B'''{{sub|1}} || 24 – 35
|style="text-align:right"| 55{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; great
| '''C''' – '''B''' || '''C'''{{sub|2}} – '''B'''{{sub|2}} || 36 – 47
|style="text-align:right"| 110{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; small
| '''c''' – '''b''' || '''C'''{{sub|3}} – '''B'''{{sub|3}} || 48 – 59
|style="text-align:right"| 220{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; one-lined
| '''c′<nowiki/>''' – '''b′<nowiki/>''' || '''C'''{{sub|4}} – '''B'''{{sub|4}} || 60 – 71
|style="text-align:right"| 440{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; two-lined
| '''c″''' – '''b″''' || '''C'''{{sub|5}} – '''B'''{{sub|5}} || 72 – 83
|style="text-align:right"| 880{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; three-lined
| '''c‴''' – '''b‴''' || '''C'''{{sub|6}} – '''B'''{{sub|6}} || 84 – 95
|style="text-align:right"| 1 760{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; four-lined
| '''c⁗''' – '''b⁗''' || '''C'''{{sub|7}} – '''B'''{{sub|7}} || {{0}}96 – 107
|style="text-align:right"| 3 520{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; five-lined
| '''c″‴''' – '''b″‴''' || '''C'''{{sub|8}} – '''B'''{{sub|8}} || 108 – 119
|style="text-align:right"| 7 040{{0|.00}} &emsp;
|-
|style="text-align:left"| &nbsp; six-lined
| '''c″⁗''' – '''b″⁗''' || '''C'''{{sub|9}} – '''B'''{{sub|9}} || 120 – 127<br/>(<small>ends at '''G'''<sub>9</sub></small>)
|style="text-align:right"| 14 080{{0|.00}} &emsp;
|}