Turn on, turn off the appliance, low-frequency hum: Listen & Download Turn off the appliance,, Turn on .mp3 Error! Change your browser, please! ⇓ Download Electronic energy, shutdown,, start up ⚠ Electric transformer ⚠ Small electric motor ⚠ Electric discharges, Tesla coil ⚠ Low frequency rumble ⚠ Electrical discharge surge ⚠ Button click ⚠ Toggle switch, Small switch ⚠ Switch ⚠ Wall switch ⚠ Turn off the appliance,, Turn on ⚠ Jacob’s ladder, Electric discharges ⚠ ★★★★★