Perfect fourth: Difference between revisions
m removed the "(interval region)" text from infobox |
Infobox placement; style |
||
| Line 1: | Line 1: | ||
{{About|the [[interval region]]|the just perfect fourth|4/3}} | {{About|the [[interval region]]|the just perfect fourth|4/3}} | ||
{{Wikipedia}} | |||
A '''perfect fourth''' ('''P4''') is the smaller and most common of the two fourths – intervals spanning 4 degrees or 3 scale steps in the diatonic scale. It is found between the 1st and 4th degrees of all diatonic modes except Lydian. Another diatonic interval around the same size is the '''augmented third''' ('''A3'''). More generally, an interval close to 500 cents can be called a perfect fourth. | |||
== As an interval region == | |||
{{Infobox interval region | {{Infobox interval region | ||
| Name = Perfect fourth | | Name = Perfect fourth | ||
| Line 9: | Line 14: | ||
| MOSes = [[5L 2s]], [[2L 5s]], [[5L 3s]], [[7L 2s]], [[2L 7s]] | | MOSes = [[5L 2s]], [[2L 5s]], [[5L 3s]], [[7L 2s]], [[2L 7s]] | ||
| Complement = [[Perfect fifth]] | | Complement = [[Perfect fifth]] | ||
| Lower region = [[ | | Lower region = [[Major third]] | ||
| Higher region = [[Semi-augmented fourth]] <br> [[Tritone]] | | Higher region = [[Semi-augmented fourth]] <br> [[Tritone]] | ||
}} | }} | ||
As an [[interval region]], the perfect fourth is typically near 500{{c}} in size, distinct from the [[semiaugmented fourth]] of roughly 550{{c}}. A rough tuning range for the perfect fourth is about 470 to 530{{c}} according to [[Margo Schulter]]'s theory of interval regions. Another common range is the stricter range from 480 to 514{{c}}, which generates a diatonic scale. | As an [[interval region]], the perfect fourth is typically near 500{{c}} in size, distinct from the [[semiaugmented fourth]] of roughly 550{{c}}. A rough tuning range for the perfect fourth is about 470 to 530{{c}} according to [[Margo Schulter]]'s theory of interval regions. Another common range is the stricter range from 480 to 514{{c}}, which generates a diatonic scale. | ||
This article covers intervals from 450 to 540{{c}}. | This article covers intervals from 450 to 540{{c}}. | ||
=== In | === In mos scales === | ||
Intervals between 450 and 545 cents generate the following [[mos | Intervals between 450 and 545 cents generate the following [[mos scale]]s: | ||
These tables start from the last monolarge mos generated by the interval range. | These tables start from the last monolarge mos generated by the interval range. | ||
| Line 29: | Line 31: | ||
|- | |- | ||
! Range | ! Range | ||
! colspan="6" | | ! colspan="6" | Mos | ||
|- | |- | ||
| 450–480{{c}} | | 450–480{{c}} | ||
| Line 66: | Line 68: | ||
=== Scale info === | === Scale info === | ||
The diatonic scale contains six perfect fourths. In the Ionian mode, perfect fourths are found on all but the fourth degree of the scale, which has an [[ | The diatonic scale contains six perfect fourths. In the Ionian mode, perfect fourths are found on all but the fourth degree of the scale, which has an [[augmented fourth]]. The strong presence of perfect fourths as opposed to their augmented counterparts leads to fourths (along with fifths) being the most fundamental intervals for diatonic harmony. | ||
== In just intonation == | == In just intonation == | ||
=== By prime limit === | === By prime limit === | ||
| Line 72: | Line 75: | ||
Other "out of tune" fourths in higher [[prime limit|limits]] include: | Other "out of tune" fourths in higher [[prime limit|limits]] include: | ||
* The 5-limit '''acute fourth''' is a ratio of [[27/20]], and is about 520{{c}} | * The 5-limit '''acute fourth''' is a ratio of [[27/20]], and is about 520{{c}} | ||
* The 7-limit '''subfourth''' is a ratio of [[21/16]], and is about 471{{c}}. | * The 7-limit '''subfourth''' is a ratio of [[21/16]], and is about 471{{c}}. | ||
| Line 115: | Line 117: | ||
== In edos == | == In edos == | ||
The following table lists the best tuning of 4/3, as well as other fourths if present, in various significant [[edo]]s. | The following table lists the best tuning of 4/3, as well as other fourths if present, in various significant [[edo]]s. | ||
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||