Late '80s TV sets seem to aim for good audio quality

[ha1156w]

Wasn't it true that the FCC rules limited the frequency response of TV broadcasts in the late 60's/early 70's? I think it was 100Hz-5kHz? This would explain the cheezy audio on some of those higher end sets. If the FCC won't let it be broadcast, then why waste engineering and money to equip a set with "good" audio? Put the money into some other googaw for the set (not that there was a lack of gimmicks on sets back then to begin with). I haven't been able to determine of any reasoning behind the limitation, only that they did it.