I was soldering components onto a circuit board that was placed on a rubber-like soldering mat on a table. Simultaneously, I was listening to audio from my desktop computer, using wired headphones. The computer and the soldering iron were plugged into different power outlets within the same room. I hear electric pops through the headphones every time the tip of the soldering iron and the soldering wire simultaneously touch the metal parts of the components that I’m soldering.
Is this normal, and is it something to worry about? What is it a sign of?