I downloaded this app to record a funny sound my HVAC is making (intermittently, but never in front of the technician), and it worked! The sound in question is crystal clear, even through the ambient sounds of the blower motor, air passing through the vents, and burners on fire. It was a little hard to figure out where to find the recording (and I still don't know where it's stored on my actual phone), but otherwise, it's a great, simple, effective app!