While walking down 6th St., Kentuckiana Sounds curator Aaron Rosenblum found himself enveloped in a droning, omnipresent hum reverberating among the buildings on the block. Was it coming from an HVAC system? Or from the service vehicles parked nearby with giant tubes protruding from their trailers? Or from somewhere else entirely? To hear the full recording, explore the sound map, or submit a sound visit www.wfpl.org/sounds or www.kentuckianasounds.org.