18/1

Interval information

Ratio	18/1
Factorization	2 × 32
Monzo	[1 2⟩
Size in cents	5003.91¢
Name	18th harmonic
FJS name	[math]\text{M30}[/math]
Special properties	harmonic
Tenney height (log2 nd)	4.16993
Weil height (log2 max(n, d))	8.33985
Wilson height (sopfr(nd))	8
Harmonic entropy (Shannon, [math]\sqrt{nd}[/math])	~2.37457 bits
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18/1, the 18th harmonic, is the harmonic past 17/1 and before 19/1. It is about four octaves and two semitones in size. Used in harmony, it sounds particularly wide: if the lower note is C2, the higher note will be about D6. Think of a soprano and a bass at their extremes. Like 12/1, it can be approached in various ways of stacking, such as 1–2–3–6–9–18, an alternate sequence of octaves and fifths.

See also

• 9/8 – its octave-reduced form