Factory atmosphere, drone in a mine tunnel: Listen & Download Drone in a mine tunnel, Factory atmosphere .mp3 Error! Change your browser, please! ⇓ Download Electric generator (hum) ⚠ Low frequency running engine ⚠ Gas welding ⚠ Steam pump ⚠ Welding transformer operation under load ⚠ Canning machine ⚠ Working,, turning on, Welding transformer ⚠ Electric welding ⚠ Hydraulic down machine ⚠ Hydraulic pump ⚠ Air compressor turn on, turn off ⚠ Power station turbine ⚠ ★★★★★