Frequency ratio: Difference between revisions

m Moving from Category:Term to Category:Terms using Cat-a-lot
m Added Wikipedia box, misc. edits
Line 5: Line 5:
| ja =  
| ja =  
}}
}}
A '''frequency ratio''' (in this wiki mostly shortened to '''ratio''') is the relationship between the frequencies of two sound waves. For example, a piano string vibrating at 110 Hz (110 times per second) and a piano string vibrating at 220 Hz are in a 2:1 ratio (since 220/110 reduces to 2/1).
{{Wikipedia|Interval ratio}}
A '''frequency ratio''' (often shortened to '''ratio''') is the relationship between the frequencies of the [[pitch]]es of two or more notes. For example, a piano string vibrating at 110 Hz (110 times per second) and a piano string vibrating at 220 Hz are in a 2:1 ratio (since 220/110 reduces to 2/1).


Although mostly written in the form (<code>larger/smaller</code>) throughout this wiki, ratios of frequencies may be written several ways:
[[Interval]]s can be expressed as ratios. Although mostly written in the form <code>larger/smaller</code> throughout this wiki, they may be written in several ways:


* 2/1, 2:1, 1/2, 1:2 ([[octave]])
* 2/1, 2:1, 1/2, 1:2 ([[octave]])
* 3/2, 3:2, 2/3, 2:3 ([[just fifth]])
* 3/2, 3:2, 2/3, 2:3 ([[3/2|just fifth]])


When the larger number is written first (<code>note/base</code>), this usually signifies a note being played ''above'' some base tone (perhaps the starting note of a scale). When the smaller number is written first (<code>base/note</code>), this usually signifies the note being played ''below'' that base tone.
When the larger number is written first (<code>note/base</code>), this usually signifies a note being played ''above'' some base tone (perhaps the starting note of a scale). When the smaller number is written first (<code>base/note</code>), this usually signifies the note being played ''below'' that base tone.


The [http://en.wikipedia.org/wiki/Harmonic_series_%28music%29 harmonic series] can be represented as a ratio - 1:2:3:4:5:6:7:8:9:10:11:12:13:14:15:16:17... etc.
[[Chord]]s with three or more notes can also be expressed as ratios. For example, the just intoned major chord in root position is 4:5:6. (When chords are expressed as ratios, the above rule about the notes being above or below a base tone doesn't usually apply). Chords can also be written as a string of intervals, such as the major chord 1/1–5/4–3/2.


Chords can also be expressed as ratios. For example, the just intoned major chord in root position is 4:5:6. (When chords are expressed as ratios, the above rule about the notes being above or below a base tone doesn't usually apply). Chords can also be written as a string of intervals, such as the major chord 1/1–5/4–3/2
The [[harmonic series]] can be represented as the infinite ratio 1:2:3:4:5:6:7:8:9:10:11:12:13:14:15:16:17…


In the context of just intonation, ratios are almost always used to label and identify intervals and chords. However, the use of ratios to identify intervals and chords in tempered scales is also common - in these cases, it is implied that the notes are in the ''approximate'' ratio indicated. For example, a common shorthand expression might be ''"4:6:7:9:11 chords in [[17edo|17-EDO]]"'' - which really means ''"The [[chords]] in which the notes are in the approximate ratio of 4:6:7:9:11 in 17-EDO".''
In the context of just intonation, ratios are almost always used to label and identify intervals and chords. However, the use of ratios to identify intervals and chords in tempered scales is also common - in these cases, it is implied that the notes are in the ''approximate'' ratio indicated. For example, a common shorthand expression might be "4:6:7:9:11 chords in [[17edo]]", which really means "the chords in which the notes are in the approximate ratio of 4:6:7:9:11 in 17edo".


[[Category:Basics]]
[[Category:Ratio| ]] <!-- main article -->
[[Category:Frequency]]
[[Category:Notation]]
[[Category:Ratio]]
[[Category:Theory]]
[[Category:Theory]]
[[Category:Terms]]
[[Category:Terms]]