It's not easy to labor in purposeful obscurity for more than a decade, cultivating an atmosphere of secrecy and hard-line artistic weirdness, but Olympia's Dead Air Fresheners have been going strong (and going secretive) for nigh on 13 years now. The creatively-uncontained, nominally-instrumental band (sometimes joined by spoken word performers) is a regular at Oly's Experimental Music Fest, where their droning, shrieking, aleatoric sounds are warmly received by the attendees' hard-bitten cochleae.  With their rotating roster of masked improvisers, a Dead Air Fresheners performance is like a Halloween-themed edition of "Guess Who?" simultaneously piquing the audience's curiosity and forcing them to forgo any desire to relate to the musicians themselves and asking them instead to focus all their attention on the thrumming, effects-addled vibrations being generated. 

[Northern, with Crank Sturgeon, Styrofoam Sanchez, Derek M Johnson, Soup Purse, 8 p.m., all-ages, 321 Fourth Ave., Olympia, northernolympia.org]