NTSC audio is FM'ed on a 4.5MHz subcarrier, which subsequently modulates the transmitted carrier (channel) frequency. You won't be able to recover the audio with a TV unless you modulate it onto a carrier that the TV can tune. Well, I guess if you blasted the TV with 4.5MHz FM'ed audio at close range with high power, you MIGHT be able to recover the audio, but I doubt that that's what you have in mind.