I completely disagree with audioguru for the reason he gave with respect to the use of FM in TV audio.There is an interesting reason why the picture is amplitude modulated and sound is freq.modulated in TV and not vice versa.
Itz because, when we freq.modulate a carrier directly(Direct FM), its phase varies indirectly.Our ears are insensitive to these phase variations and hence we dont find any problem while listening to the audio in TV.
If, the picture is freq.modulated, its phase varies indirectly(as said earlier)and our eyes are very sensitive to these phase variations whereby one sees a picture distorted if it is freq.modulated.
Hence, sound is freq.modulated and picture is amplitude modulated in TV to overcome these problems of indirect phase variations.