Maqamat

The maqamat are the melodic modes of Arabic music that a reciter may carry the recitation on — among them Bayati, Saba, Hijaz, Rast, Nahawand, Sikah and ‘Ajam.

Used well, the mode follows the meaning: Saba where the verses carry grief, Hijaz where they carry awe. Used carelessly, it pulls the listener toward the voice and away from the words.

The governing rule is that melody serves tajweed and never bends it: no madd lengthened, and none shortened, for the sake of a tune.