A process of injecting a certain amount of hum into a signal at an opposite polarity of hum already present. The net result is cancellation of the hum thereby producing a clean signal. Humbucking is normally provided by a coil, which is very efficient at picking up hum producing electromagnetic fields (EMI) such as those produced by high power equipment like lights, motors, etc. The concept was applied to guitars many years ago. It is called the humbucking pickup (a.k.a. humbucker). Guitar output signals are generally very easily compromised by stray fields due to the magnet and coil nature of the typical guitar pickup. The humbucker provides cancellation of the hum right at the source so the guitar’s output is clean.