From the first humid week through the last, the unit fills the lower sash of a bedroom or living room window, propped level with a shim of folded cardboard and sealed at the edges with foam strips that never quite match the gap they are cut for. The compressor's cycle has a signature as distinct as a voice: a low steady drone, interrupted every eleven or twelve minutes by a harder clunk as the compressor kicks back on, followed by thirty seconds of pitch climbing before it settles. Rooms that sleep with the unit running develop a kind of hearing loss for it specifically, the sound sorted into background so completely that its absence, during a power outage, wakes people up.
Field listening across several specimens turns up real variation: window units from the nineties run lower and rounder, closer to a cello's open string, while newer digital models produce a thinner, higher whine layered over the compressor hum, plus an intermittent electronic beep that serves no apparent purpose. The drip, meanwhile, is its own instrument entirely, condensation collecting on the back coil and falling in irregular intervals onto pavement, gravel, or whatever unlucky hosta has been planted beneath the sill. No two units drip in the same rhythm, and no manufacturer has ever tried to fix that.