tv aerial issues

[paz28]

I have a small L.G. TV with video which i have connected an aerial to so i can watch terrestial tv on it. when i watch videos on this tv, the sound and vision quality is fine, but when i try to watch tv on it, even if the picture quality is good, the sound quality is horrific. why is this, and what can i do to fix it? thanks

[mxyzptlk]

May be not quite on tune.