Apparently MS is tired of hearing teens scream profanities and others yelling racial slurs. Here's a article from joystiq that talks about it:
Microsoft has patented an audio censoring technology with obvious application to Xbox Live. The patent covers real-time and batch analysis of audio data streams with the ability to render "undesired" words or phrases unintelligible or inaudible. Can you imagine if this power falls into the wrong hands?
The process allegedly uses sophisticated comparisons of phonemes, the little building blocks of language. Our guess: What you thought was last year's harmless flu shot was actually a nanomachine injection, obviously. Just don't be surprised when you fire up Xbox Live a few months from now to the sound of tweens screaming: La-li-lu-le-lo!