Persian Music Scales · Historical Theory Series

A scholarly interactive edition

Al-Urmawī Advar Atlas

Explore al-Urmawī’s exact fret divisions, intervals, and modal theory.

Exact rational model4 languagesWorks offline
Advar Atlas
Persian Music Scales · Historical Theory Series
في أقسام الدساتين On the Divisions of the Frets
Ṣafī al-Dīn al-Urmawī · geometry, exact ratios, listening, construction, and training
Scholarly interactive edition 18 exact pitch points 1200-cent octave 4-language interface
17 positions + octave · exact rational data
Combined theoretical + practical view
Limma Comma
F: focus · 1/2/3: view · Esc: exit
م — bridge (mashṭ) Select any fret to inspect and hear it ا — nut (anf) · open string
Al-Urmawī monochord A horizontal string from bridge to nut with seventeen pitch positions and the octave.
100%
Illustrative four-string mapping — not a reconstruction of a specific surviving instrument
Guided curriculum ا · 1/1 · 0.000¢
FoundationSource + modern explanation

String length and pitch

Objective: understand why shorter sounding length produces higher pitch.
ا
Open string
alif · position 1 of 18
String length1/1
Frequency ratio1/1
Cents0.000¢
Frequency220.00 Hz
From bridge100.00 cm
From nut0.00 cm
Previous step—
Pitch order1 / 18
Geometry → acoustics
ا · 0.000¢

The governing relationship

The whole sounding string is normalized to 1. If the remaining sounding length is ℓ, the ideal frequency ratio is its reciprocal.

frequency = 220 × (1/1) = 220.00 Hz

The 18 written points represent the open string, 17 pitch positions within the octave, and the octave repetition. They form a parent pitch lattice, not a single mandatory performance scale.

Source-guided constructionModern wording
Step 0 of 17
ا

Begin with the open string

Normalize the complete sounding length to 1. This is the reference tone.

length(ا) = 1/1 → frequency(ا) = 1/1

The ratios are exact. The explanatory English is a cautious pedagogical paraphrase of the supplied diagrams and instructions.

Geometrical operation
ا
Full normalized string: bridge م at left, nut ا at right.
Length
1/1
Frequency
1/1
Cents
0.000¢
Sound AtlasWeb Audio
220 Hz

For theoretical comparison, a sine wave makes beating and interval size easier to hear. The sound is a modern synthesis, not a reconstruction of a medieval instrument timbre.

Compare two positions1/1
ا
alif
220.00 Hz
0.000¢
A ↔ B
701.955¢
يا
yā-alif
330.00 Hz
701.955¢
Species Atlas
Interactive training0 correct / 0

Loading question…

Exact pitch lattice · ascending order Hz calculated at 220 Hz
#LabelString lengthFrequency ratioCentsHzPrevious step