I'm sorry if this is too vague, I'm not thinking of a specific instance when this happened. There have been at least several times when I've been debugging the source of some unwanted electrical noise that is either mitigated or eliminated entirely when I put my hand close to the wire or trace that the noise is on, and I was suddenly curious about it again this morning.
I understand that me being close to the wire capacitively couples me with the wire, and I understand how this capacitance could introduce to some low-pass filter behavior into the circuit. I'm confused why only the noise (not the intended signal) is affected by my hand. Does it have to do with the relative drive strength of the signals?
What does electrical noise that is mitigated by a human hand tell us about the noise itself? Are there common fixes for noise that is mitigated by proximity to a hand/human?