Fun fact: In 1958, "Lawrence Welk's Plymouth Show" (the precursor to "The Lawrence Welk Show") was the first show to be broadcast in stereo in the US.
...but stereo televisions hadn't even been invented yet.
To get the full audio, you would turn on the TV to get the picture and the one audio signal, and then you were supposed to turn on the radio broadcast for the other half of the audio.