Persian Vocal Stylings
Vocal music, like the rest of Persian music, is learned by heart from a master, the definitive form of the traditional style being handed down from generation to generation. Musically, the voice is classed in three registers or dongs (tetrachords): Do Dong (long), Chahar dong (middle), and Shish dong (high). This last can sometimes reach higher than a normal soprano.
A characteristic of Persian vocal styling is voice crackling called tahrir which is used as an ornament or trill. It is similar to the Swiss yodel, the Slavic voice cracking, or what we hear in Japanese or Korean singing. The tahrir is known by laymen as “chah-chah”, but for the more informed, there are various types, such as “tahrir bolbuli” or “tahrir chakoshi.” The tahrir ornament is used in phrases which have long syllables, and it usually falls at the end of a hemistiche, but never in the middle.
The experienced performer often chooses from a renowned poet such as Hafez or Sa`adi a poem or a verse extract sympathetic to the character or mood of the accompanying gusheh.