Developed over centuries among the semi-nomadic herdsmen of Tuva, where they could sing to each other over long distances, the eerie vocalizations have long been a national passion in the land bordering southern Siberia. The singers use the larynx to simultaneously produce multiple tones.

As exotic as they are, however, the sounds and songs soon yielded familiar points of reference. The ultra-low quaking tones that first emerged from the singers suggested cartoon voices, like Popeye chanting in measured phrases. The subsequent higher tones sounded like a synthesizer or pleasantly modulating electric device.

And then there were the nature sounds, melodic representations of bird tweets, baying wolves, winds sweeping across the steppes and, above all, horses - key in Tuva's equine culture. Sean Quirk, the young Chicagoan who manages and interprets for Alash, introduced a solo vocal from drummer Ayan Shirizhik (on a goatskin-covered kengirge), in borbangnadyr style - literally "to cause something to make itself round" - and asked the 200-plus listeners to imagine a cyclically burbling stream. Easily done.

Quirk also introduced the important "Lament of the Igil" selection, which relates the folk tale of a beloved horse's ghost instructing the grieving owner to make and play an igil, a bowed, two-stringed, horse-head fiddle. (Nice synchronicity at the anniversary of Barbaro's passing.) Bady-Dorzhu Ondar, 23, began on the instrument (he can be seen on YouTube making his American TV debut at age 9 with Alash artistic director Kongar-ool Ondar, the master vocalist who was featured in the award-winning 1999 documentary Genghis Blues).

Philadelphia's eight-piece Extra (Special) Terrestrial (Guests) - half of the band coming from the legendary Sun Ra Arkestra, the first American jazz band to play in Tuva, in 2004 - later did a rousing set of free jazz improv. Their performance featured worldly groove assistance from South African percussionist Mogauwane Mahloele, and renowned local musician Elliot Levin, matching eruptive sax chops with octogenarian Arkestra leader Marshall Allen. The show closed with Alash coming out to lead a sublime group jam on the Tuvan standard "The Caravan-Driver Song."