The announcement of an unaccompanied solo jazz bass performance could conceivably empty a room even of jazz fans; the mere concept underlies at least three pretty good jokes I've heard in recent months. The instrument doesn't promise enough variety and range for the solo format, and too many bassists have met the problem by resorting to unorthodox techniques that can sound forced and even silly. But Tatsu Aoki won't inspire any jokes. He has harnessed his technique to the yoke of clear communication, and his emphasis on rhythmic propulsion--the bass violin's traditional role in jazz--allows him to retain our interest with otherwise far-flung improvisations. (He does this, too, by the occasional use of mild electronic effects, and by keeping each of his compositions brief and pointed.) Aoki's set will also feature a percussionist playing the Japanese taiko--something like an oversized Asian conga drum--on four songs from Aoki's upcoming album, which incorporates traditional Japanese music into his freeflowing style. Aoki performs as part of the second annual HotHouse Music Festival, which begins Thursday, January 13, and continues through Sunday, and which might as well be called "Shut Up and Learn" for its preponderance of lesser-known artists and bands. Some to watch for include the Lost Kwartet, a quirky band led by New Horizons guitarist Jeff Parker (Friday at 11 PM); the much-traveled flamenco guitarist Tomas de Utrera, who appears Sunday at 4; and yet another guitarist, Fareed Haque, whose trio plays Sunday night at 8. Aoki appears Saturday at 10 PM. HotHouse, 1565 N. Milwaukee; 235-2334.