Until the 1990s, the only Westerners who knew much about Tannu-Tuva were stamp collectors bemused by the diamond- and triangle-shaped stamps that came from the small Russian republic on the Mongolian border. That began to change in 1987, when musicologist Ted Levin recorded the 1990 Smithsonian Folkways album Tuva: Voices From the Center of Asia, America’s first exposure to the eerie but entrancing world of Tuvan throat singing. Through some well-practiced glottal gymnastics, a singer produces two or three notes simultaneously–often a low, steady drone paired with dynamic whistling. Rescued from the doldrums of philately, Tuva has found a new cultural ambassador in the quartet Huun-Huur-Tu, throat singing’s best-known practitioners. The almost uncanny strangeness of their singing style is offset by the familiarity of the music’s loping, cowboy-song rhythm, and the simplicity of instrumentation: drum, Jew’s harp, stringed instruments plucked and bowed. Thanks to the surprise success of Genghis Blues, the 1999 Oscar-nominated documentary on Tuvan music, and Huun-Huur-Tu’s own work with Frank Zappa and the Kronos Quartet, there’s now a sizable audience for the group. Their appearances are genial, user-friendly affairs–part concert and part clinic on the finer points of the singing styles xoomei and kargyraa. Western success, however, apparently means suffering the indignity of the remix: the group’s most recent album, last year’s Spirits From Tuva (Paras), funked up and trancified their catalog to no useful effect. When dealing with a style of music whose essence is the sounds and rhythms of nature, such tweakings seem especially misguided. Better introductions: 1999’s Where Young Grass Grows, 2001’s Live 1 and Live 2, or either of these two concerts. Friday, January 30, 7:30 and 10 PM, Old Town School of Folk Music, 4544 N. Lincoln; 773-728-6000.