"It's pronounced teh-track-tiss," explains Stuart McLeod shortly before a rehearsal for Tetraktys, named after a glyph that the followers of Pythagoras believed had mystical powers. Crammed with the six musicians of SIL2K (Strategic Improv Laboratories) into McLeod's studio, I observe a read-through of this rhythmically charged piece.

Melding video, narration, improvisation, and composition, Tetraktys is a kind of atheist's oratorio. Set to a spoken text, De Rerum Natura ("On the Nature of Things") by the Roman philosopher Lucretius, lines like "the universe was simply not created for us by Divine Power" mesh well with the collaborative process brewing among the performers. How often do you hear a composer exhort musicians to treat the score as a grid instead of a firm guide? Early in the rehearsal, McLeod reminds everyone, "Don't feel like you have to play every single note."

Later, McLeod tells me that the tetraktys—a triangle made out of 10 dots in four rows—represents the four elements (earth, air, fire, and water) as well as symbolizes numerical unity, a fixation of form-obsessed composers for millennia.

I can hear the numbers in the music: Urgent pulses of four, five, and seven permeate the various movements in Tetraktys. Electronic squiggles, ringing Tibetan cymbals, keyboards, and cello drop in and out of the score, droning, accenting, and propelling an undercurrent of sound that accompanies and sometimes floods narrator Rachel Lissman.

Two stalwarts of Seattle's experimental electronics scene close the show. Billed as "Intonarumori versus inBOIL," the two one-man projects perform short sets and then join their distinct sound worlds: Intonarumori deploys extended loops that molt strange, gently shadowed flickers of distortion while inBOIL amplifies small granules of sound, scooping them up and stretching them out with filters, delays, and other sonic processes. recommended

Catch Tetraktys Fri Nov 7, Rendezvous, 2322 Second Ave, 441-5823, 7:30 pm, $5, 21+.

Classical, Jazz & Avant Calendar

Thurs 11/6

PACIFIC NORTHWEST BALLET

Despite my love for Steve Reich's music, I'm not too keen on his 1986 work Three Movements for Orchestra. It's the symphonic equivalent of an oak table—sturdy, well built, and, after a glance, boring. Unlike Reich's big hits (Music for 18 Musicians, Tehillim, etc.), which use timbre and pulsation to tilt you toward an unexpected harmonic horizon, Three Movements just chugs along with no destination in sight. Yet movement can decipher musical relationships that stationary ears miss, so I hope choreographer Benjamin Millepied's 3 Movements reveals something new about this overlooked item in Reich's catalog. Other pieces in the "New Works" program include M-Pulse with music by Juilliard grad Cristina Spinei and Mark Morris's A Garden. Through Sun Nov 16; see www.pnb.org for a complete schedule. McCaw Hall, 321 Mercer St, 441-2424, 7:30 pm, $25–$155.

TUNING THE AIR

I can't decide what is more impressive about Seattle Circle: their collective precision or the seating arrangement of eight guitarists surrounding the audience. It's like being inside a giant zither; strums, chords, and melodies not only sail over your head, they tilt and rotate around you. The music ranges from winning covers of "Kashmir" and Brian Wilson's inconsolable lament "In My Room" to pieces influenced by the classical guitar tradition, flamenco, and progressive rock. Arrive early for a plum seat in the center. Every Thurs through Dec 18. Fremont Abbey Arts Center, 4272 Fremont Ave N, 789-8481, 8 pm, $10.

Fri 11/7

SARA GAZAREK

Steady touring and a spate of festival appearances have ripened this vocalist, a graduate of the jazz program at Roosevelt High School. Sara Gazarek keeps getting better, honing her near-pinpoint phrasing and accruing some world-weary grit in her falsetto. Kirkland Performance Center, 350 Kirkland Ave, 547-9787, 8 pm, $10/$29.

MESSIAEN ORGAN CYCLE

Commemorating the centenary of Olivier Messiaen (1908–1992), the fourth installment of this cycle continues with the Livre du Saint Sacrement. For his final work for the organ, Messiaen stuffed the Livre with teetering clusters in the "Adore te," roof-rattling chords, spacey synthlike tones cribbed from Tangerine Dream (especially in the movement "La Manne et le Pain de Vie"), and roaring fanfares that portend a galactic apocalypse. The 17 movements of the Livre also testify to one of Messiaen's key contributions to the 20th century: the transmutation of a forgotten backwater of classical music—the organ recital with its attendant "symphonies" and improvisation—into a transcendent aural experience rivaling (and sometimes trumping) the symphony orchestra concert. Subsequent performances in the series are Fri Nov 21 and Sun Dec 7. St. James Cathedral, 804 Ninth Ave, 382-4874, 8 pm, $15 suggested donation, students and seniors pay as able.

Sat 11/8

SPACE IN THE HEART

Every year the Earshot Jazz Festival serves up at least one work that busts across genres. Here, clarinetist Bill Smith premieres his opera for three singers and jazz trio. When I interviewed Smith last spring, he showed me part of the score to Space in the Heart, which frames sung melodies with trio improvisation. Smith told me, "It's a love story set in space." Jazz sage and Earshot magazine guru Peter Monaghan penned the libretto. For a preview, catch the free open rehearsal at noon. Also Fri Nov 7. PONCHO Concert Hall at Cornish College, 710 E Roy St, 547-9787, 8 pm, $18.

Wed 11/12

COMPOSER SPOTLIGHT

Composers usually discover their overlooked progenitors before anyone else, so I'm eager to hear Sean Osborn champion the obscure clarinet pioneer Cyrille Rose (1830–1902). The composer and clarinetist demonstrates Rose's études as well as his pioneering use of quarter tones. Jack Straw Productions, 4261 Roosevelt Way NE, 634-0919, 7:30 pm, free.

IL MONDO DELLA LUNA

This must be the week for extraterrestrial operas. Students from the UW School of Music stage Haydn's comedic opera set, in part, on the moon: A quack astronomer helps a prince and his servant convince an overprotective father to let them marry his daughter and her maid. The lunar travel is a hoax—anyone remember O. J. Simpson and Capricorn One?—and an excuse for hilarity rooted in disguised identities. Also Fri Nov 14 at 7:30 pm and Sun Nov 16 at 3 pm. Meany Theater, UW Campus, 543-4880, 7:30 pm, $15/$25.