HumSilencer Eliminates Electrical Hum Without Causing Signal Distortion

Electrical hum is the most common source of background noise in electrophysiology experiments. It is caused by the alternating current (AC) of the electrical mains, delivered via power outlets. This background noise interferes with biological signals of interest. We have previously demonstrated that the HumSilencer™ Adaptive Noise Cancellation feature of our Axon™ Digidata® 1550 Series digitizers successfully eliminate 50 Hz or 60 Hz line-frequency hum and its associated high frequency harmonics in a variety of electrophysiology applications1. Some of our customers still question whether the underlying HumSilencer algorithm either (a) distorts the acquired biological signal in any way, (b) removes 50/60 Hz frequencies that are part of the biological signal, and (c) is able to distinguish between 50/60 Hz frequencies that are caused by background interference, and 50/60 Hz frequencies within the biological signal, and only removes the former. These questions will be addressed in this application note.