Can a song be considered a living thing? The tracks laid down by A Living Soundtrack — a local instrumental quartet consisting of Rotary Downs alum Matt Aguiluz along with Nick Lauve, Marshall Flaig and Jenn Gosnell — seem to breathe, blossom and bloom rather than verse, chorus and bridge. Witness “Germination,” a disorienting cut off the band’s self-titled 2006 debut, whose four primary voices are an inquisitive acoustic guitar, a Massively Attacking bass-beat hammer, a nervy R2D2 computer and, finally, a reverberating Dr. Who synthesizer that quiets the crowd in preparation for the refracted third-act coda. It’s a lovely kind of auditory decompression sickness, the bends in frequency form.    

A Living Soundtrack performs at the Dragon’s Den, 435 Esplanade Ave., tonight at 9 p.m.