The name of the person?
Do you mind me asking where you're located? Voice search has a lot to do with the accent/dialect of the person using it, but you can get around that (to a point) by selecting an alternative language in Settings -> Voice Input & Output -> Voice recognizer settings.
You'll see that for English, there's a few selections (Canadian, US, Australia etc.) so your accent has a fair bit to do with the voice searches ability to understand the command. Have a play about, see if you can get something that works, then let me know.
As an aside, I've never found voice search to be that accurate anyway.