BBC Radio Five Live asked for help from a deaf lip reader, Jessica Rees, who read the words phonetically to an Italian translator.
She deciphered the insult as being "you're the son of a terrorist whore" - a translation also carried by many national newspapers in Britain on Tuesday.
The BBC's Ten O'Clock News also called in experts to study the television footage of the incident and determined the following:
Materazzi's first word to Zidane was "no" before he then told him to "calm down".
He then accused him of being a "liar" and wished "an ugly death to you and your family" on the day the Frenchman's mother had been taken to hospital ill. This was followed by "Go f*** yourself".
Zidane's agent, Alain Migliaccio, has hinted that Zidane will soon reveal exactly what was said by Materazzi.
Piara Powar, national co-ordinator for the anti-racism group Kick It Out told Five Live, said: "If there was a racial slur then Fifa needs to act."
Keith Hackett, head of referees in England, said that if it can be proved that Matterazzi racially abused the Frenchman, then Fifa should take retrospective action for "the good of the game."