Speaker Wires on Carpet

I was reading that carpet will interfere with the signal going through speaker wires if the wires are on the carpet. I was wondering if the amount of interference varies depending on whether the positive and negative wires are twisted together versus running straight and parallel to each other. Also, will certain types of wire jackets cut down on interfence?

I ask this because I have wires running next to the base boards on the floor in my (carpeted) dining room since that's the most unobtrusive place for them. I may consider some type of wire elevators if they are reasonably priced and look nice.

Thanks in advance for any advice.