Bulgarian vocals are said to be "open-throated", though this is actually a misnomer. Singers actually constrict their throats to amplify the voice's focus and strength, giving it a distinctive sound.
Regional styles abound in Bulgaria. Dobrudzha, Sofia, Rodopi, Thrace and the northwestern Danube shore all have distinctive sounds. Folk music revolved around holidays like Christmas, New Year's Day and the Feast of St. Lazarus, as well as the unusual Nestinarstvo rites from Strandzha, where villagers fell into a trance and danced on hot coals as part of the feast of Sts Konstantin and Elena. Music was also a part of more personal celebrations, accompanying weddings and the departure of young men for military service.
Bands frequently use instruments that include gaida (bagpipes), gadulka (a bowed string instrument), tapan (drum), kaval (end-blown flute) and tambura (a strummed string instrument). These were the instruments chosen by the Communist government to be used in new orchestras following World War 2. The new professional musicians of traditional Bulgarian instruments soon reached new heights of innovation, expanding the capacities of the gaida (Kostadin Varimezov and Nikola Atanasov), gadulka (Mihail Marinov, Atanas Vulchev) and kaval (Nikola Ganchev, Soyan Velichkov). Other, factory-made instruments had arrived in Bulgaria in the 19th century, and included the accordion. Bulgarian accordion music was defined by Boris Karloff and later Gypsy musicians including Kosta Kolev and Ibro Lolov. In 1965, the Ministry of Culture founded the Koprivshtitsa music festival, which has become an important annual event showcasing Bulgarian music.
The most important state-supported orchestra of this era was the Sofia-based State Ensemble for Folk Songs and Dances, led by Philip Koutev. Koutev has become perhaps the most influential musician of 20th century Bulgaria, and updated rural music with more accessible harmonies to great domestic acclaim.
During the Communist era, some musicians lived outside the state-supported music scene. Without official support, wedding bands were also without official limitations on their music, leading to fusions with foreign styles and instruments. Thrace was an important center of this music, which was entirely underground until the mid-1980s when a triennial music festival was set up near Stambolovo (hence the genre's current name, Stambolovski orkestri) and artists like Ivo Papasov, Sever, Trakiîski Solisti, Shoumen and Juzhni Vetar became popular, especially clarinetist Papasov.