Week 8 – Jss 2 Third Term Cultural And Creative Art (CCA) Lesson Notes

CLASS; J S S 2 WEEK 8
TOPIC; INTERVALS.

Interval (music)

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Melodic and harmonic intervals. 
In music theory, an interval is the difference between two pitches. 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.
In Western music, intervals are most commonly differences between notes of a diatonic scale. The smallest of these intervals is a semitone. Intervals smaller than a semitone are called microtones. They can be formed using the notes of various kinds of non-diatonic scales. Some of the very smallest ones are called commas, and describe small discrepancies, observed in some tuning systems, between enharmonically equivalent notes such as C♯ and D♭. Intervals can be arbitrarily small, and even imperceptible to the human ear.
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 quality (perfect, major, minor, augmented, and diminished) and number (unison, second, third, etc.). Examples include the minor third or perfect fifth. These names describe not only the difference in semitones between the upper and lower notes, but also how the interval is spelled. The importance of spelling stems from the historical practice of differentiating the frequency ratios of enharmonic intervals such as G–G♯ and G–A♭.

Main intervals.

The table shows the most widely used conventional names for the intervals between the notes of a chromatic scale. A perfect unison (also known as perfect prime)
is an interval formed by two identical notes. Its size is zero cents. A semitone is any interval between two adjacent notes in a chromatic scale, a whole tone is an interval spanning two semitones (for example, a major second), and a triton is an interval spanning three tones, or six semitones (for example, an augmented fourth). Rarely, the term denote is also used to indicate an interval spanning two whole tones (for example, a major third), or more strictly as a synonym of major third.
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 will also have the same width. Namely, all semitones will have a width of 100 cents, and all intervals spanning 4 semitones will be 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 ofsemitones	Minor, major,or perfect intervals	Short	Augmented ordiminished intervals	Short	Widely usedalternative names	Short	Audio
0	Perfect unison[5][7]	P1	Diminished second	d2			Play (help info)
1	Minor second	m2	Augmented unison[5][7]	A1	Semitone,[8] half tone, half step	S	Play (help info)
2	Major second	M2	Diminished third	d3	Tone, whole tone, whole step	T	Play (help info)
3	Minor third	m3	Augmented second	A2			Play (help info)
4	Major third	M3	Diminished fourth	d4			Play (help info)
5	Perfect fourth	P4	Augmented third	A3			Play (help info)
6			Diminished fifth	d5	Triton[6]	TT	Play (help info)
Augmented fourth	A4
7	Perfect fifth	P5	Diminished sixth	d6			Play (help info)
8	Minor sixth	m6	Augmented fifth	A5			Play (help info)
9	Major sixth	M6	Diminished seventh	d7			Play (help info)
10	Minor seventh	m7	Augmented sixth	A6			Play (help info)
11	Major seventh	M7	Diminished octave	d8			Play (help info)
12	Perfect octave	P8	Augmented seventh	A7			Play (help info)

Interval number and quality