Component video cable used to carry sound?

I have a sound problem related to my plasma TV and our digital cable box.

This was installed by an electrician and the video works wonderfully - via component cables. The sound from the TV's speakers is not great.

If I am watching any program with background noise (e.g. crowd applause, music, etc.) then the conversation of anyone talking during the program is difficult to hear.

When I looked at the audio connections for the first time yesterday, the electrician has used a second component video cord (with the three colored connectors) to hook up sound. What he has done is simply not use the green one and used the other two going into the red/white audio connector on the cable box.

So, my question is whether or not this may be the source of my strange audio problem wherein the background noise/music drowns out the conversation on a program??

Thanks for your consideration.