What? Cant hear the voices

My wife and I 55 yrs ish are now having trouble hearing the voices clearly over laugh track and music backrounds on TV shows and movies on DVD. We have a great 38 inch Lowe HD tube TV, embedded in a great two channel sound system. Right now we get the best sound just using the two stereo speakers (Von Sweikert Vr4 SR's) and turning off the TV volume. My question is the best way to proceed. Is there a way to just add a center speaker and a reciever to handle it perhaps with prologic 2? Not interested in surround etc, just clearer voices. Thanks