I have pioneer speakers installed in my car. For the past 6 months there seems to be a humming noise coming out of the speakers. Its when im driveing and the noise varys with speed. As i go higher in rpms the humm goes louder. and vis versa. I did some research and found out i should check the ignition system noise suppression devices. But what in the world are those?

 

Skip the ignition system and check all speakers for ground issues. Also if you are using an amp try to separate power wires from signal wires (i.e power down driver side and signal down passenger). It really sounds to me like a ground problem.

 

in simple terms, capacitors / noise filters.

you probably only get it when using the AM band, and to a lesser extent the FM,
next to nothing with a CD / tape player, right?

 

I only use the fm and cd player ususally, and it humms on both settings.