Modulation is a technique used during the melodic development of a Maqam. In simple terms, modulation means shifting the emphasis from one jins to another. The new jins may start on the same note (common-tone modulation), or on a different note.

What makes a modulation successful (pleasing to the ear) is adhering to compatible combinations of ajnas long established in the Arabic music tradition. These are best acquired by listening.

The simplest way to modulate is to develop the maqam's upper jins after having developed the lower jins. Another way is to develop one of the maqam's secondary ajnas (e.g. exploiting the Ajam trichords in maqam Bayati, etc). Such a secondary jins can be developed into the full scale of the new maqam, before going back to the original scale.

Another common modulation technique is to replace the maqam's upper jins with another jins of the same size. In this case the new resulting maqam is a variant of the same maqam (they fall under the same family since they have the same starting jins). An example of this technique is starting with maqam Rast and replacing the upper Rast tetrachord with Hijaz, which is a modulation to maqam Suznak. Another example is starting with maqam Hijaz, and replacing the upper Nahawand tetrachord with Hijaz, which is a modulation to maqam Hijaz Kar.

The pivot note for such a transition would be the dominant, which is generally the starting note of the upper jins. The dominant is also considered the second most important note in the scale, and can be used to shift the modal emphasis.

The reciprocal modulation would be keeping the upper jins and replacing the lower jins with another one of the same size. This would modulate to a maqam in a new family, and can sound quite dramatic. An example of this technique is starting with maqam Hijaz and replacing the lower Hijaz tetrachord with the Bayati tetrachord, which is a modulation to maqam Bayati.

Another modulation technique exploits similarities between ajnas, by going back and forth between an incomplete jins and its full version. For example the first 3 notes of the Nahawand tetrachord can lead to the Nawa Athar tetrachord, the first 3 notes of the Bayati tetrachord can lead to the Saba tetrachord, and the first 3 notes of the Kurd tetrachord can lead to the Athar Kurd tetrachord. Modulation can also work in the opposite direction (from Nawa Athar to Nahawand, etc).

Another modulation technique is replacing one jins with another one that differs by only one note. The most common example is going between the Nahawand and Rast tetrachords, or between the Nawa Athar and Athar Kurd tetrachords.

Some groups of ajnas are very frequently interchangeable during modulation. The first group (whose dominant note is the 4th) is made of the Bayati, Hijaz and Kurd ajnas. The second group (whose dominant note is the 5th) is made of the Rast, Nahawand, Ajam and Nawa Athar ajnas.

In more general terms, modulation means moving from one maqam to another compatible one. There are well-established maqam combinations that sound very pleasant and are learned through experience. The musician can carry on transitioning from one maqam to the next, but usually returns to the starting maqam unless the purpose of the modulation was to end up on a new maqam. In a complex improvisation, the musician can modulate over half a dozen or more maqamat.

Modulation is a very important technique which shows the true richness and beauty of the maqam system, and requires a lot of experience and knowledge of the maqamat their constituent ajnas (sets).

Modulation Example 1:

Taqsim oud in Maqam Bayati (from: Taqaseem Oud by Riad Al Sunbati - © Sono Cairo - SIDI Music)

Part	Play	Time Range	Description
1		00:00 - 00:17	Maqam Bayati on D is introduced, with emphasis on the tonic note (D). The lower tetrachord is the Bayati Tetrachord on D, and the upper tetrachord is the Nahawand Tetrachord on G.
2		00:18 - 01:13	Maqam Bayati is developped with emphasis on the 2nd, 3rd and 4th notes (E, F and G).
3		01:14 - 01:49	Maqam Bayati is developped further with emphasis on the 4th and 5th notes (G and A), with a touch on the upper tonic note (upper D).
4		01:50 - 02:10	The first modulation is achieved by developing a seconday jins within the original maqam: the Ajam Trichord on B. Another secondary jins is hinted at: the Ajam Trichord on F.
5		02:11 - 02:43	A new and very popular modulation is Maqam Bayati Shuri on D. Modulation was achhieved by replacing the upper Nahawand Tetrachord on G with the Hijaz Tetrachord on G, where G is the dominant note of both maqams.
6		02:44 - 3:17	Maqam Bayati is developped fully by emphasizing the upper tonic note (upper D). Modulation on Maqam Husseini was achieved by changing the 6th note from B to B. This amounts to replacing the upper Nahawand Tetrachord on G with the Rast Tetrachord on G, where G is the dominant note of both maqams. At the very end of this part, Maqam Bayati Shuri is hinted at by playing A instead of A.
7		3:18 - 4:07	Similar modulation to part 4, by developing a seconday jins within the original maqam: the Ajam Trichord on B.
8		4:08 - 4:36	A new and very popular modulation is Maqam Saba on D.
9		4:37 - 4:52	Closing part where a descending scale in played in Maqam Bayati.