Many home TVs have relatively low fidelity speakers which accentuate upper mid-range and high frequencies, while the human voice tends to be in the mid-audio range. The rest of the sound spectrum, which would ideally help keep music and voices distinct, is often deficient on home televisions. In contrast, most program producers and editors work in studios outfitted with the best sound systems, and determine the balance of voices and music in programs based on their acoustically superior technology. A further complication is the gradual loss of frequency range in the human ear over time.
TV sets with better audio systems offer controls that may improve the listening experience. Stereo and digital sets with "surround (or enhanced) sound" tend to enhance the low and high ranges (which is where the music is), while ignoring or dampening the mid-range (which is where the voice usually is). When there is a music/voice balance problem, try switching from "stereo to mono" or switching off the "surround sound."
The relative positions of the television set, speakers, and the viewer may also improve or degrade the sound balance. If moving any are an option, try to find a position which reduces echoes from walls or furniture.