hum

Hum is unwanted low-frequency noise that can appear in a guitar signal path¹. It can be introduced by ground loops, which allow stray magnetic fields to enter the signal path, a problem that becomes likely when modulation and delay pedals are used². Single-coil pickups are associated with 60-cycle hum³, and buffering can lower a signal's susceptibility to hum and buzz caused by radio interference and electromagnetic fields⁴. Noise gates are designed to remove hum, hiss, and feedback from the signal, especially in high-gain rigs⁵⁶. Some pedals and power supplies are noted for operating with minimal or almost inaudible hum⁷⁸.