Ethiopian music uses a distinct modal system that is pentatonic, with characteristically long intervals between some notes. The music of the highlands uses a fundamental modal system called qenet, of which there are four main modes: tezeta, bati, ambassel, and anchihoy. Three additional modes are variations on the above: tezeta minor, bati major, and bati minor.Some songs take the name of their qenet, such as tizita, a song of reminiscence. When played on traditional instruments, these modes are generally not tempered (that is, the pitches may deviate slightly from the Western-tempered tuning system), but when played on Western instruments such as pianos and guitars, they are played using the Western-tempered tuning system. Music in the Ethiopian highlands is generally monophonic or heterophonic. In certain southern areas, some music is polyphonic. Dorze polyphonic singing (edho) may employ up to five parts; Majangir, four parts. Ethiopia is a musically traditional country. Of course, popular music is played, recorded and listened to, but most musicians also sing traditional songs, and most audiences choose to listen to both popular and traditional styles. A long-standing popular musical tradition in Ethiopia was that of brass bands, imported from Jerusalem in the form of forty Armenian orphans (Arba Lijoch) during the reign of Haile Selassie. This band, which arrived in Addis Ababa on September 6, 1924, became the first official orchestra of Ethiopia. By the end of World War II, large orchestras accompanied singers; the most prominent orchestras were the Army Band, Police Band, and Imperial Bodyguard Band. From the 1950s to the 1970s, Ethiopian popular musicians included woyesa tilahun, Mahmoud Ahmed, Alemayehu Eshete, Hirut Bekele, Ali Birra, Ayalew Mesfin, Kiros Alemayehu, Muluken Melesse and Tilahun Gessesse, while popular folk musicians included Alemu Aga, Kassa Tessema, Ketema Makonnen, Asnaketch Worku, and Mary Armede. Perhaps the most influential musician of the period, however, was Ethio-jazz innovator Mulatu Astatke. Amha Records, Kaifa Records, and Philips-Ethiopia were prominent Ethiopian record labels during this era. Since 1997, Buda Musique s Éthiopiques series has compiled many of these singles and albums on compact disc. During the 1980s, the Derg controlled Ethiopia, and emigration became almost impossible. Musicians during this period included Ethio Stars, Wallias Band and Roha Band, though the singer Neway Debebe was most popular. He helped to popularize the use of seminna-werq (wax and gold, a poetic form of double entendre) in music (previously only used in qiné, or poetry) that often enabled singers to criticize the government without upsetting the censors.