Interval (music)

In music theory, an interval is a difference in pitch between two sounds.[1] An interval may be described as horizontal, linear, or melodic if it refers to successively sounding tones, such as two adjacent pitches in a melody, and vertical or harmonic if it pertains to simultaneously sounding tones, such as in a chord.[2][3]
In
In physical terms, an interval is the ratio between two sonic frequencies. For example, any two notes an octave apart have a frequency ratio of 2:1. This means that successive increments of pitch by the same interval result in an exponential increase of frequency, even though the human ear perceives this as a linear increase in pitch. For this reason, intervals are often measured in cents, a unit derived from the logarithm of the frequency ratio.
In Western music theory, the most common naming scheme for intervals describes two properties of the interval: the
Size

The size of an interval (also known as its width or height) can be represented using two alternative and equivalently valid methods, each appropriate to a different context: frequency ratios or cents.
Frequency ratios
The size of an interval between two notes may be measured by the
Most commonly, however, musical instruments are nowadays tuned using a different tuning system, called
Cents
The standard system for comparing interval sizes is with cents. The cent is a logarithmic unit of measurement. If frequency is expressed in a logarithmic scale, and along that scale the distance between a given frequency and its double (also called octave) is divided into 1200 equal parts, each of these parts is one cent. In twelve-tone equal temperament (12-TET), a tuning system in which all semitones have the same size, the size of one semitone is exactly 100 cents. Hence, in 12-TET the cent can be also defined as one hundredth of a semitone.
Mathematically, the size in cents of the interval from frequency f1 to frequency f2 is
Main intervals
The table shows the most widely used conventional names for the intervals between the notes of a
Intervals with different names may span the same number of semitones, and may even have the same width. For instance, the interval from D to F♯ is a major third, while that from D to G♭ is a diminished fourth. However, they both span 4 semitones. If the instrument is tuned so that the 12 notes of the chromatic scale are equally spaced (as in equal temperament), these intervals also have the same width. Namely, all semitones have a width of 100 cents, and all intervals spanning 4 semitones are 400 cents wide.
The names listed here cannot be determined by counting semitones alone. The rules to determine them are explained below. Other names, determined with different naming conventions, are listed in a separate section. Intervals smaller than one semitone (commas or microtones) and larger than one octave (compound intervals) are introduced below.
Number of semitones |
Minor, major, or perfect intervals |
Short | Augmented or diminished intervals |
Short | Widely used alternative names |
Short | Audio |
---|---|---|---|---|---|---|---|
0 | Perfect unison |
P1 | Diminished second | d2 | ⓘ | ||
1 | Minor second |
m2 | Augmented unison | A1 | Semitone, half tone, half step | S | ⓘ |
2 | Major second | M2 | Diminished third | d3 | Tone , whole tone, whole step |
T | ⓘ |
3 | Minor third | m3 | Augmented second | A2 | ⓘ | ||
4 | Major third | M3 | Diminished fourth | d4 | ⓘ | ||
5 | Perfect fourth | P4 | Augmented third | A3 | ⓘ | ||
6 | Diminished fifth | d5 | Tritone | TT | ⓘ | ||
Augmented fourth | A4 | ||||||
7 | Perfect fifth | P5 | Diminished sixth | d6 | ⓘ | ||
8 | Minor sixth | m6 | Augmented fifth | A5 | ⓘ | ||
9 | Major sixth | M6 | Diminished seventh | d7 | ⓘ | ||
10 | Minor seventh | m7 | Augmented sixth | A6 | ⓘ | ||
11 | Major seventh | M7 | Diminished octave | d8 | ⓘ | ||
12 | Perfect octave | P8 | Augmented seventh | A7 | ⓘ |
Interval number and quality

In Western music theory, an interval is named according to its number (also called diatonic number) and quality. For instance, major third (or M3) is an interval name, in which the term major (M) describes the quality of the interval, and third (3) indicates its number.
Number

The number of an interval is the number of letter names or
There is a
If one adds any accidentals to the notes that form an interval, by definition the notes do not change their staff positions. As a consequence, any interval has the same interval number as the corresponding natural interval, formed by the same notes without accidentals. For instance, the intervals C–G♯ (spanning 8 semitones) and C♯–G (spanning 6 semitones) are fifths, like the corresponding natural interval C–G (7 semitones).
Notice that interval numbers represent an inclusive count of encompassed staff positions or note names, not the difference between the endpoints. In other words, one starts counting the lower pitch as one, not zero. For that reason, the interval C–C, a perfect unison, is called a prime (meaning "1"), even though there is no difference between the endpoints. Continuing, the interval C–D is a second, but D is only one staff position, or diatonic-scale degree, above C. Similarly, C–E is a third, but E is only two staff positions above C, and so on. As a consequence, joining two intervals always yields an interval number one less than their sum. For instance, the intervals C–E and E–G are thirds, but joined together they form a fifth (C–G), not a sixth. Similarly, a stack of three thirds, such as C–E, E–G, and G–B, is a seventh (C–B), not a ninth.
This scheme applies to intervals up to an octave (12 semitones). For larger intervals, see § Compound intervals below.
Quality

The name of any interval is further qualified using the terms perfect (P),
Perfect

Perfect intervals are so-called because they were traditionally considered perfectly consonant,[6] although in Western classical music the perfect fourth was sometimes regarded as a less than perfect consonance, when its function was contrapuntal.[vague] Conversely, minor, major, augmented or diminished intervals are typically considered less consonant, and were traditionally classified as mediocre consonances, imperfect consonances, or dissonances.[6]
Within a diatonic scale[b] all unisons (P1) and octaves (P8) are perfect. Most fourths and fifths are also perfect (P4 and P5), with five and seven semitones respectively. One occurrence of a fourth is augmented (A4) and one fifth is diminished (d5), both spanning six semitones. For instance, in a C-major scale, the A4 is between F and B, and the d5 is between B and F (see table).
By definition, the inversion of a perfect interval is also perfect. Since the inversion does not change the pitch class of the two notes, it hardly affects their level of consonance (matching of their harmonics). Conversely, other kinds of intervals have the opposite quality with respect to their inversion. The inversion of a major interval is a minor interval, the inversion of an augmented interval is a diminished interval.
Major and minor

As shown in the table, a diatonic scale[b] defines seven intervals for each interval number, each starting from a different note (seven unisons, seven seconds, etc.). The intervals formed by the notes of a diatonic scale are called diatonic. Except for unisons and octaves, the diatonic intervals with a given interval number always occur in two sizes, which differ by one semitone. For example, six of the fifths span seven semitones. The other one spans six semitones. Four of the thirds span three semitones, the others four. If one of the two versions is a perfect interval, the other is called either diminished (i.e. narrowed by one semitone) or augmented (i.e. widened by one semitone). Otherwise, the larger version is called major, the smaller one minor. For instance, since a 7-semitone fifth is a perfect interval (P5), the 6-semitone fifth is called "diminished fifth" (d5). Conversely, since neither kind of third is perfect, the larger one is called "major third" (M3), the smaller one "minor third" (m3).
Within a diatonic scale,[b] unisons and octaves are always qualified as perfect, fourths as either perfect or augmented, fifths as perfect or diminished, and all the other intervals (seconds, thirds, sixths, sevenths) as major or minor.
Augmented and diminished

Augmented intervals are wider by one semitone than perfect or major intervals, while having the same interval number (i.e., encompassing the same number of staff positions): they are wider by a
The augmented fourth (A4) and the diminished fifth (d5) are the only augmented and diminished intervals that appear in diatonic scales[b] (see table).
Example
Neither the number, nor the quality of an interval can be determined by counting
For example, as shown in the table below, there are four semitones between A♭ and B♯, between A and C♯, between A and D♭, and between A♯ and E, but
- A♭–B♯ is a second, as it encompasses two staff positions (A, B), and it is doubly augmented, as it exceeds a major second (such as A–B) by two semitones.
- A–C♯ is a third, as it encompasses three staff positions (A, B, C), and it is major, as it spans 4 semitones.
- A–D♭ is a fourth, as it encompasses four staff positions (A, B, C, D), and it is diminished, as it falls short of a perfect fourth (such as A–D) by one semitone.
- A♯-E
is a fifth, as it encompasses five staff positions (A, B, C, D, E), and it is triply diminished, as it falls short of a perfect fifth (such as A–E) by three semitones.
Number of semitones |
Interval name | Staff positions
| ||||
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | ||
4 | doubly augmented second (AA2) | A♭ | B♯ | |||
4 | major third (M3) | A | C♯ | |||
4 | diminished fourth (d4) | A | D♭ | |||
4 | triply diminished fifth (ddd5) |
A♯ | E![]() |
Shorthand notation
Intervals are often abbreviated with a P for perfect, m for minor, M for major, d for diminished, A for augmented, followed by the interval number. The indications M and P are often omitted. The octave is P8, and a unison is usually referred to simply as "a unison" but can be labeled P1. The tritone, an augmented fourth or diminished fifth is often TT. The interval qualities may be also abbreviated with perf, min, maj, dim, aug. Examples:
- m2 (or min2): minor second,
- M3 (or maj3): major third,
- A4 (or aug4): augmented fourth,
- d5 (or dim5): diminished fifth,
- P5 (or perf5): perfect fifth.
Inversion

A simple interval (i.e., an interval smaller than or equal to an octave) may be inverted by raising the lower pitch an octave or lowering the upper pitch an octave. For example, the fourth from a lower C to a higher F may be inverted to make a fifth, from a lower F to a higher C.
There are two rules to determine the number and quality of the inversion of any simple interval:[7]
- The interval number and the number of its inversion always add up to nine (4 + 5 = 9, in the example just given).
- The inversion of a major interval is a minor interval, and vice versa; the inversion of a perfect interval is also perfect; the inversion of an augmented interval is a diminished interval, and vice versa; the inversion of a doubly augmented interval is a doubly diminished interval, and vice versa.
For example, the interval from C to the E♭ above it is a minor third. By the two rules just given, the interval from E♭ to the C above it must be a major sixth.
Since compound intervals are larger than an octave, "the inversion of any compound interval is always the same as the inversion of the simple interval from which it is compounded".[8]
For intervals identified by their ratio, the inversion is determined by reversing the ratio and multiplying the ratio by 2 until it is greater than 1. For example, the inversion of a 5:4 ratio is an 8:5 ratio.
For intervals identified by an integer number of semitones, the inversion is obtained by subtracting that number from 12.
Since an interval class is the lower number selected among the interval integer and its inversion, interval classes cannot be inverted.
Classification
Intervals can be described, classified, or compared with each other according to various criteria.

Melodic and harmonic
An interval can be described as
- Vertical or harmonic if the two notes sound simultaneously
- Horizontal, linear, or melodic if they sound successively.[2] Melodic intervals can be ascending (lower pitch precedes higher pitch) or descending.
Diatonic and chromatic
In general,
- A diatonic interval is an interval formed by two notes of a diatonic scale.
- A chromatic interval is a non-diatonic interval formed by two notes of a chromatic scale.
The table above depicts the 56 diatonic intervals formed by the notes of the C major scale (a diatonic scale). Notice that these intervals, as well as any other diatonic interval, can be also formed by the notes of a chromatic scale.
The distinction between diatonic and chromatic intervals is controversial, as it is based on the definition of diatonic scale, which is variable in the literature. For example, the interval B–E♭ (a diminished fourth, occurring in the harmonic C-minor scale) is considered diatonic if the harmonic minor scales are considered diatonic as well.[9] Otherwise, it is considered chromatic. For further details, see the main article.
By a commonly used definition of diatonic scale

The distinction between diatonic and chromatic intervals may be also sensitive to context. The above-mentioned 56 intervals formed by the C-major scale are sometimes called diatonic to C major. All other intervals are called chromatic to C major. For instance, the perfect fifth A♭–E♭ is chromatic to C major, because A♭ and E♭ are not contained in the C major scale. However, it is diatonic to others, such as the A♭ major scale.
Consonant and dissonant
Consonance and dissonance are relative terms that refer to the stability, or state of repose, of particular musical effects. Dissonant intervals are those that cause tension and desire to be resolved to consonant intervals.
These terms are relative to the usage of different compositional styles.
- In 15th- and 16th-century usage, perfect fifths and octaves, and major and minor thirds and sixths were considered harmonically consonant, and all other intervals dissonant, including the perfect fourth, which by 1473 was described (by Johannes Tinctoris) as dissonant, except between the upper parts of a vertical sonority—for example, with a supporting third below ("6-3 chords").[10] In the common practice period, it makes more sense to speak of consonant and dissonant chords, and certain intervals previously considered dissonant (such as minor sevenths) became acceptable in certain contexts. However, 16th-century practice was still taught to beginning musicians throughout this period.
- Hermann von Helmholtz (1821–1894) theorised that dissonance was caused by the presence of beats.[11] Helmholtz further believed that the beating produced by the upper partials of harmonic sounds was the cause of dissonance for intervals too far apart to produce beating between the fundamentals.[12] Helmholtz then designated that two harmonic tones that shared common low partials would be more consonant, as they produced less beats.[13][14] Helmholtz disregarded partials above the seventh, as he believed that they were not audible enough to have significant effect.[15] From this Helmholtz categorises the octave, perfect fifth, perfect fourth, major sixth, major third, and minor third as consonant, in decreasing value, and other intervals as dissonant.
- David Cope (1997) suggests the concept of interval strength,[16] in which an interval's strength, consonance, or stability is determined by its approximation to a lower and stronger, or higher and weaker, position in the harmonic series. See also: Lipps–Meyer law and #Interval root
All of the above analyses refer to vertical (simultaneous) intervals.
Simple and compound

A simple interval is an interval spanning at most one octave (see Main intervals above). Intervals spanning more than one octave are called compound intervals, as they can be obtained by adding one or more octaves to a simple interval (see below for details).[17]
Steps and skips
Linear (melodic) intervals may be described as steps or skips. A step, or conjunct motion,[18]
is a linear interval between two consecutive notes of a scale. Any larger interval is called a skip (also called a leap), or disjunct motion.
For example, C to D (major second) is a step, whereas C to E (major third) is a skip.
More generally, a step is a smaller or narrower interval in a musical line, and a skip is a wider or larger interval, where the categorization of intervals into steps and skips is determined by the tuning system and the pitch space used.
Melodic motion in which the interval between any two consecutive pitches is no more than a step, or, less strictly, where skips are rare, is called stepwise or conjunct melodic motion, as opposed to skipwise or disjunct melodic motions, characterized by frequent skips.
Enharmonic intervals

Two intervals are considered enharmonic, or enharmonically equivalent, if they both contain the same pitches spelled in different ways; that is, if the notes in the two intervals are themselves enharmonically equivalent. Enharmonic intervals span the same number of semitones.
For example, the four intervals listed in the table below are all enharmonically equivalent, because the notes F♯ and G♭ indicate the same pitch, and the same is true for A♯ and B♭. All these intervals span four semitones.
Number of semitones |
Interval name | Staff positions
| |||
---|---|---|---|---|---|
1 | 2 | 3 | 4 | ||
4 | major third | F♯ | A♯ | ||
4 | major third | G♭ | B♭ | ||
4 | diminished fourth | F♯ | B♭ | ||
4 | doubly augmented second | G♭ | A♯ |
When played as isolated chords on a
The discussion above assumes the use of the prevalent tuning system,
Minute intervals

There are also a number of minute intervals not found in the chromatic scale or labeled with a diatonic function, which have names of their own. They may be described as
- A Pythagorean comma is the difference between twelve justly tuned perfect fifths and seven octaves. It is expressed by the frequency ratio 531441:524288 (23.5 cents).
- A syntonic comma is the difference between four justly tuned perfect fifths and two octaves plus a major third. It is expressed by the ratio 81:80 (21.5 cents).
- A septimal comma is 64:63 (27.3 cents), and is the difference between the Pythagorean or 3-limit "7th" and the "harmonic 7th".
- A diesis is generally used to mean the difference between three justly tuned major thirds and one octave. It is expressed by the ratio 128:125 (41.1 cents). However, it has been used to mean other small intervals: see diesis for details.
- A diaschisma is the difference between three octaves and four justly tuned perfect fifths plus two justly tuned major thirds. It is expressed by the ratio 2048:2025 (19.6 cents).
- A schisma (also skhisma) is the difference between five octaves and eight justly tuned fifths plus one justly tuned major third. It is expressed by the ratio 32805:32768 (2.0 cents). It is also the difference between the Pythagorean and syntonic commas. (A schismic major third is a schisma different from a just major third, eight fifths down and five octaves up, F♭ in C.)
- A kleisma is the difference between six minor thirds and one tritave or perfect twelfth (an octave plus a perfect fifth), with a frequency ratio of 15625:15552 (8.1 cents) (ⓘ).
- A septimal kleisma is the amount that two major thirds of 5:4 and a septimal major third, or supermajor third, of 9:7 exceeds the octave. Ratio 225:224 (7.7 cents).
- A quarter tone is half the width of a semitone, which is half the width of a whole tone. It is equal to exactly 50 cents.
Compound intervals

A compound interval is an interval spanning more than one octave.[17] Conversely, intervals spanning at most one octave are called simple intervals (see Main intervals below).
In general, a compound interval may be defined by a sequence or "stack" of two or more simple intervals of any kind. For instance, a major tenth (two staff positions above one octave), also called compound major third, spans one octave plus one major third.
Any compound interval can be always decomposed into one or more octaves plus one simple interval. For instance, a major seventeenth can be decomposed into two octaves and one major third, and this is the reason why it is called a compound major third, even when it is built by adding up four fifths.
The diatonic number DNc of a compound interval formed from n simple intervals with diatonic numbers DN1, DN2, ..., DNn, is determined by:
which can also be written as:
The quality of a compound interval is determined by the quality of the simple interval on which it is based. For instance, a compound major third is a major tenth (1+(8−1)+(3−1) = 10), or a major seventeenth (1+(8−1)+(8−1)+(3−1) = 17), and a compound perfect fifth is a perfect twelfth (1+(8−1)+(5−1) = 12) or a perfect nineteenth (1+(8−1)+(8−1)+(5−1) = 19). Notice that two octaves are a fifteenth, not a sixteenth (1+(8−1)+(8−1) = 15). Similarly, three octaves are a twenty-second (1+3×(8−1) = 22), and so on.
Main compound intervals
Number of semitones |
Minor, major, or perfect intervals |
Short | Augmented or diminished intervals |
Short |
---|---|---|---|---|
12 | Diminished ninth | d9 | ||
13 | Minor ninth |
m9 | Augmented octave | A8 |
14 | Major ninth |
M9 | Diminished tenth | d10 |
15 | Minor tenth |
m10 | Augmented ninth |
A9 |
16 | Major tenth |
M10 | Diminished eleventh | d11 |
17 | Perfect eleventh |
P11 | Augmented tenth | A10 |
18 | Diminished twelfth | d12 | ||
Augmented eleventh |
A11 | |||
19 | Tritave |
P12 | Diminished thirteenth | d13 |
20 | Minor thirteenth | m13 | Augmented twelfth | A12 |
21 | Major thirteenth | M13 | Diminished fourteenth | d14 |
22 | Minor fourteenth | m14 | Augmented thirteenth | A13 |
23 | Major fourteenth | M14 | Diminished fifteenth | d15 |
24 | Perfect fifteenth or Double octave | P15 | Augmented fourteenth | A14 |
25 | Augmented fifteenth | A15 |
It is also worth mentioning here the major seventeenth (28 semitones)—an interval larger than two octaves that can be considered a multiple of a perfect fifth (7 semitones) as it can be decomposed into four perfect fifths (7 × 4 = 28 semitones), or two octaves plus a major third (12 + 12 + 4 = 28 semitones). Intervals larger than a major seventeenth seldom come up, most often being referred to by their compound names, for example "two octaves plus a fifth"[19] rather than "a 19th".
Intervals in chords
Chords are sets of three or more notes. They are typically defined as the combination of intervals starting from a common note called the
Chord qualities and interval qualities
The main chord qualities are
Deducing component intervals from chord names and symbols
The main rules to decode chord names or symbols are summarized below. Further details are given at
- For 3-note chords (main articlefor further details.
- Without contrary information, a major triad) are implied. For instance, a C chord is a C major triad, and the name C minor seventh (Cm7) implies a minor 3rd by rule 1, a perfect 5th by this rule, and a minor 7thby definition (see below). This rule has one exception (see next rule).
- When the fifth interval is diminished, the third must be minor.[d]This rule overrides rule 2. For instance, Cdim7 implies a diminished 5th by rule 1, a minor 3rd by this rule, and a diminished 7th by definition (see below).
- Names and symbols that contain only a plain interval number (e.g., "seventh chord") or the chord root and a number (e.g., "C seventh", or C7) are interpreted as follows:
- If the number is 2, 4, 6, etc., the chord is a major names and symbols for added tone chords).
- If the number is 7, 9, 11, 13, etc., the chord is extended chords).
- If the number is 5, the chord (technically not a chord in the traditional sense, but a dyad) is a power chord. Only the root, a perfect fifth and usually an octave are played.
- If the number is 2, 4, 6, etc., the chord is a major
The table shows the intervals contained in some of the main chords (component intervals), and some of the symbols used to denote them. The interval qualities or numbers in
Main chords | Component intervals | |||
---|---|---|---|---|
Name | Symbol examples
|
Third | Fifth | Seventh |
Major triad |
C | M3 | P5 | |
CM, or Cmaj | M3 | P5 | ||
Minor triad |
Cm, or Cmin | m3 | P5 | |
Augmented triad | C+, or Caug | M3 | A5 | |
Diminished triad | C°, or Cdim | m3 | d5 | |
Dominant seventh chord | C7, or Cdom7 | M3 | P5 | m7 |
Minor seventh chord | Cm7, or Cmin7 | m3 | P5 | m7 |
Major seventh chord | CM7, or Cmaj7 | M3 | P5 | M7 |
Augmented seventh chord | C+7, Caug7, C7♯5, or C7aug5 |
M3 | A5 | m7 |
Diminished seventh chord | C°7, or Cdim7 | m3 | d5 | d7 |
Half-diminished seventh chord | Cø7, Cm7♭5, or Cm7dim5 | m3 | d5 | m7 |
Size of intervals used in different tuning systems
Number of semitones |
Name | 5-limit tuning (pitch ratio) |
Comparison of interval width (in cents) | |||
---|---|---|---|---|---|---|
5-limit tuning
|
Pythagorean tuning |
1⁄4-comma meantone |
Equal temperament | |||
0 | Perfect unison | 1:1 | 0 | 0 | 0 | 0 |
1 | Minor second | 16:15 27:25 |
112 133 |
90 | 117 | 100 |
2 | Major second | 9:8 10:9 |
204 182 |
204 | 193 | 200 |
3 | Minor third | 6:5 32:27 |
316 294 |
294 318 |
310 (wolf) 269 |
300 |
4 | Major third | 5:4 | 386 | 408 384 |
386 (wolf) 427 |
400 |
5 | Perfect fourth | 4:3 27:20 |
498 520 |
498 (wolf) 522 |
503 (wolf) 462 |
500 |
6 | Augmented fourth Diminished fifth |
45:32 25:18 |
590 569 |
612 588 |
579 621 |
600 |
7 | Perfect fifth | 3:2 40:27 |
702 680 |
702 (wolf) 678 |
697 (wolf) 738 |
700 |
8 | Minor sixth | 8:5 | 814 | 792 | 814 | 800 |
9 | Major sixth | 5:3 27:16 |
884 906 |
906 | 890 | 900 |
10 | Minor seventh | 16:9 9:5 |
996 1018 |
996 | 1007 | 1000 |
11 | Major seventh | 15:8 50:27 |
1088 1067 |
1110 | 1083 | 1100 |
12 | Perfect octave | 2:1 | 1200 | 1200 | 1200 | 1200 |
In this table, the interval widths used in four different tuning systems are compared. To facilitate comparison,
In
The Pythagorean tuning is characterized by smaller differences because they are multiples of a smaller ε (ε ≈ 1.96 cents, the difference between the Pythagorean fifth and the average fifth). Notice that here the fifth is wider than 700 cents, while in most meantone temperaments, including 1⁄4-comma meantone, it is tempered to a size smaller than 700. A more detailed analysis is provided at Pythagorean tuning § Size of intervals.
The
The above-mentioned symmetric scale 1, defined in the 5-limit tuning system, is not the only method to obtain
In the diatonic system, every interval has one or more enharmonic equivalents, such as augmented second for minor third.
Interval root

Although intervals are usually designated in relation to their lower note, David Cope[16] and Hindemith[21] both suggest the concept of interval root. To determine an interval's root, one locates its nearest approximation in the harmonic series. The root of a perfect fourth, then, is its top note because it is an octave of the fundamental in the hypothetical harmonic series. The bottom note of every odd diatonically numbered intervals are the roots, as are the tops of all even numbered intervals. The root of a collection of intervals or a chord is thus determined by the interval root of its strongest interval.
As to its usefulness, Cope
Interval cycles
Interval cycles, "unfold [i.e., repeat] a single recurrent interval in a series that closes with a return to the initial pitch class", and are notated by George Perle using the letter "C", for cycle, with an interval-class integer to distinguish the interval. Thus the diminished-seventh chord would be C3 and the augmented triad would be C4. A superscript may be added to distinguish between transpositions, using 0–11 to indicate the lowest pitch class in the cycle.[22]
Alternative interval naming conventions
As shown below, some of the above-mentioned intervals have alternative names, and some of them take a specific alternative name in
Typically, a comma is a diminished second, but this is not always true (for more details, see Alternative definitions of comma). For instance, in Pythagorean tuning the diminished second is a descending interval (524288:531441, or about −23.5 cents), and the Pythagorean comma is its opposite (531441:524288, or about 23.5 cents). 5-limit tuning defines four kinds of comma, three of which meet the definition of diminished second, and hence are listed in the table below. The fourth one, called syntonic comma (81:80) can neither be regarded as a diminished second, nor as its opposite. See Diminished seconds in 5-limit tuning for further details.
Number of semitones |
Generic names | Specific names | |||||
---|---|---|---|---|---|---|---|
Quality and number | Other naming convention | Pythagorean tuning | 5-limit tuning |
1⁄4-comma meantone | |||
Full | Short | ||||||
0 | perfect unison or perfect prime |
P1 | |||||
diminished second | d2 | descending Pythagorean comma (524288:531441) |
lesser diesis (128:125) | ||||
diaschisma (2048:2025) greater diesis (648:625) |
|||||||
1 | minor second |
m2 | semitone, half tone, half step |
diatonic semitone, major semitone |
limma (256:243) |
||
augmented unison or augmented prime |
A1 | chromatic semitone, minor semitone |
apotome (2187:2048) |
||||
2 | major second | M2 | tone, whole tone , whole step |
sesquioctavum (9:8) |
|||
3 | minor third | m3 | sesquiquintum (6:5) |
||||
4 | major third | M3 | sesquiquartum (5:4)
| ||||
5 | perfect fourth | P4 | sesquitertium (4:3) |
||||
6 | diminished fifth |
d5 | tritone[a] | ||||
augmented fourth |
A4 | ||||||
7 | perfect fifth | P5 | sesquialterum (3:2) | ||||
12 | perfect octave | P8 | duplex (2:1) |
Additionally, some cultures around the world have their own names for intervals found in their music. For instance, 22 kinds of intervals, called shrutis, are canonically defined in Indian classical music.
Latin nomenclature
Up to the end of the 18th century, Latin was used as an official language throughout Europe for scientific and music textbooks. In music, many English terms are derived from Latin. For instance, semitone is from Latin semitonus.
The prefix semi- is typically used herein to mean "shorter", rather than "half".[23][24][25] Namely, a semitonus, semiditonus, semidiatessaron, semidiapente, semihexachordum, semiheptachordum, or semidiapason, is shorter by one semitone than the corresponding whole interval. For instance, a semiditonus (3 semitones, or about 300 cents) is not half of a ditonus (4 semitones, or about 400 cents), but a ditonus shortened by one semitone. Moreover, in Pythagorean tuning (the most commonly used tuning system up to the 16th century), a semitritonus (d5) is smaller than a tritonus (A4) by one Pythagorean comma (about a quarter of a semitone).
Number of semitones |
Quality and number | Short | Latin nomenclature |
---|---|---|---|
0 | Perfect unison | P1 | unisonus |
1 | Minor second | m2 | semitonus |
Augmented unison | A1 | unisonus superflua | |
2 | Major second | M2 | tonus |
Diminished third | d3 | ||
3 | Minor third | m3 | semiditonus |
Augmented second | A2 | tonus superflua | |
4 | Major third | M3 | ditonus |
Diminished fourth | d4 | semidiatessaron | |
5 | Perfect fourth | P4 | diatessaron |
Augmented third | A3 | ditonus superflua | |
6 | Diminished fifth | d5 | semidiapente, semitritonus |
Augmented fourth | A4 | tritonus | |
7 | Perfect fifth | P5 | diapente |
Diminished sixth | d6 | semihexachordum | |
8 | Minor sixth | m6 | hexachordum minus, semitonus maius cum diapente, tetratonus |
Augmented fifth | A5 | diapente superflua | |
9 | Major sixth | M6 | hexachordum maius, tonus cum diapente |
Diminished seventh | d7 | semiheptachordum | |
10 | Minor seventh | m7 | heptachordum minus, semiditonus cum diapente, pentatonus |
Augmented sixth | A6 | hexachordum superflua | |
11 | Major seventh | M7 | heptachordum maius, ditonus cum diapente |
Diminished octave | d8 | semidiapason | |
12 | Perfect octave | P8 | diapason |
Augmented seventh | A7 | heptachordum superflua |
Non-diatonic intervals
Intervals in non-diatonic scales can be named using analogs of the diatonic interval names, by using a diatonic interval of similar size and distinguishing it by varying the quality, or by adding other modifiers. For example, the just interval 7/6 may be referred to as a subminor third, since it is ~267 cents wide, which is narrower than a minor third (300 cents in 12-TET, ~316 cents for the just interval 6/5), or as the
The most common of these extended qualities are a
Pitch-class intervals
In post-tonal or
In atonal or musical set theory, there are numerous types of intervals, the first being the
The interval between pitch classes may be measured with ordered and unordered pitch-class intervals. The ordered one, also called directed interval, may be considered the measure upwards, which, since we are dealing with pitch classes, depends on whichever pitch is chosen as 0. For unordered pitch-class intervals, see interval class.[27]
Generic and specific intervals
In
Notice that staff positions, when used to determine the conventional interval number (second, third, fourth, etc.), are counted including the position of the lower note of the interval, while generic interval numbers are counted excluding that position. Thus, generic interval numbers are smaller by 1, with respect to the conventional interval numbers.
Comparison
Specific interval
|
Generic interval
|
Diatonic name | |
---|---|---|---|
Number of semitones | Interval class | ||
0 | 0 | 0 | Perfect unison |
1 | 1 | 1 | Minor second |
2 | 2 | 1 | Major second |
3 | 3 | 2 | Minor third |
4 | 4 | 2 | Major third |
5 | 5 | 3 | Perfect fourth |
6 | 6 | 3 4 |
Augmented fourth Diminished fifth |
7 | 5 | 4 | Perfect fifth |
8 | 4 | 5 | Minor sixth |
9 | 3 | 5 | Major sixth |
10 | 2 | 6 | Minor seventh |
11 | 1 | 6 | Major seventh |
12 | 0 | 7 | Perfect octave |
Generalizations and non-pitch uses

The term "interval" can also be generalized to other music elements besides pitch.
For example, an interval between two bell-like sounds, which have no pitch salience, is still perceptible. When two tones have similar acoustic spectra (sets of partials), the interval is just the distance of the shift of a tone spectrum along the frequency axis, so linking to pitches as reference points is not necessary. The same principle naturally applies to pitched tones (with similar harmonic spectra), which means that intervals can be perceived "directly" without pitch recognition. This explains in particular the predominance of interval hearing over absolute pitch hearing.[30][31]
See also
- Circle of fifths
- Ear training
- List of meantone intervals
- List of pitch intervals
- Music and mathematics
- Pseudo-octave
- Regular temperament
Notes
- ^ a b The term tritone is sometimes used more strictly as a synonym of augmented fourth (A4).
- ^ a b c d e f g
The expression melodic minor and the harmonic minor scales (see also Diatonic and chromatic).
- ^ a b General rule 1 achieves consistency in the interpretation of symbols such as CM7, Cm6, and C+7. Some musicians legitimately prefer to think that, in CM7, M refers to the seventh, rather than to the third. This alternative approach is legitimate, as both the third and seventh are major, yet it is inconsistent, as a similar interpretation is impossible for Cm6 and C+7 (in Cm6, m cannot possibly refer to the sixth, which is major by definition, and in C+7, + cannot refer to the seventh, which is minor). Both approaches reveal only one of the intervals (M3 or M7), and require other rules to complete the task. Whatever is the decoding method, the result is the same (e.g., CM7 is always conventionally decoded as C–E–G–B, implying M3, P5, M7). The advantage of rule 1 is that it has no exceptions, which makes it the simplest possible approach to decode chord quality.
According to the two approaches, some may format the major seventh chord as CM7 (general rule 1: M refers to M3), and others as CM7 (alternative approach: M refers to M7). Fortunately, even CM7 becomes compatible with rule 1 if it is considered an abbreviation of CMM7, in which the first M is omitted. The omitted M is the quality of the third, and is deduced according to rule 2 (see above), consistently with the interpretation of the plain symbol C, which by the same rule stands for CM.
- ^ All triads are tertian chords (chords defined by sequences of thirds), and a major third would produce in this case a non-tertian chord. Namely, the diminished fifth spans 6 semitones from root, thus it may be decomposed into a sequence of two minor thirds, each spanning 3 semitones (m3 + m3), compatible with the definition of tertian chord. If a major third were used (4 semitones), this would entail a sequence containing a major second (M3 + M2 = 4 + 2 semitones = 6 semitones), which would not meet the definition of tertian chord.
References
- ISBN 978-0781207836
- ^ ISBN 978-1-56159-239-5.
- ISBN 978-0495189756
- ISBN 978-0-393-33420-3
- Grove Music Online. Oxford University Press. Accessed August 2013. (subscription required))
- ^ a b Definition of Perfect consonance in Godfrey Weber's General music teacher, by Godfrey Weber, 1841.
- ^ Kostka, Stefan; Payne, Dorothy (2008). Tonal Harmony, p. 21. First edition, 1984.
- ISBN 0-403-00326-1.
- ISBN 9781873497203
- ^ Drabkin, William (2001). "Fourth". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan.
- ^ Helmholtz 1895, p. 172: "The roughness from sounding two tones together depends... the number of beats produced in a second.".
- ^ Helmholtz 1895, p. 178: "The cause of this phenomenon must be looked for in the beats produced by the high upper partials of such compound tones".
- ^ Helmholtz 1895, p. 182.
- ISBN 0-486-60753-4, p. 182d: "Just as the coincidences of the two first upper partial tones led us to the natural consonances of the Octave and Fifth, the coincidences of higher upper partials would lead us to a further series of natural consonances."
- ^ Helmholtz 1895, p. 183: "Here I have stopped, because the 7th partial tone is entirely eliminated, or at least much weakened.".
- ^ ISBN 0-02-864737-8.
- ^ ISBN 9780793579914.
- ^ a b
Bonds, Mark Evan (2006).
A History of Music in Western Culture, p.123. 2nd ed. ISBN 0-13-193104-0.
- ISBN 0-87930-798-6.
- ISBN 0-14-020659-0.
- ^ Hindemith, Paul (1934). The Craft of Musical Composition. New York: Associated Music Publishers. Cited in Cope (1997), p. 40–41.
- ISBN 0-520-06991-9.
- ^ Gioseffo Zarlino, Le Istitutione harmoniche ... nelle quali, oltre le materie appartenenti alla musica, si trovano dichiarati molti luoghi di Poeti, d'Historici e di Filosofi, si come nel leggerle si potrà chiaramente vedere (Venice, 1558): 162.
- ISBN 90-04-04794-8.
- ISBN 0803279345.
- ^ a b "Extended-diatonic interval names". Xenharmonic wiki.
- ISBN 978-1-56159-239-5.
- ISBN 978-0-19-531713-8
- ISBN 0-7546-3573-2. "Lewin posits the notion of musical 'spaces' made up of elements between which we can intuit 'intervals'....Lewin gives a number of examples of musical spaces, including the diatonic gamut of pitches arranged in scalar order; the 12 pitch classes under equal temperament; a succession of time-points pulsing at regular temporal distances one time unit apart; and a family of durations, each measuring a temporal span in time units....transformations of timbre are proposed that derive from changes in the spectrum of partials..."
- ISBN 978-3-540-57394-4.
- JSTOR 40285634.
Sources
- Longmans, Green, and Co.
External links
- Gardner, Carl E. (1912): Essentials of Music Theory, p. 38
- "Interval", Encyclopædia Britannica
- Lissajous Curves: Interactive simulation of graphical representations of musical intervals, beats, interference, vibrating strings
- Elements of Harmony: Vertical Intervals
- Just intervals, from the unison to the octave, played on a drone note on YouTube