TV buzzing when showing whites and bright colours

Question

when watching sattelite tv on my boxy old standard sony tv i was getting a really annoying bizzing noise when the screen showed bright images or colours especially whites...i put this down to the grand old age of the set so went out and bought a brand new panasonic 50" full HD plasma set and yep you guessed it!...the noise is still there!!!... please help...could this be caused by a faulty cable or something as its affecting two totally different types of set????