When Siri first launched, many users found lots of names were pronounced incorrectly and couldn’t do much beyond adding phonetic spellings manually for each contact. With iOS 7, it appears that Siri can now take initiative for learning proper pronunciations.
As discovered by 9to5Mac reader RY, Siri will ask for help pronouncing a name if it has trouble understanding you the first time you pronounce a name. In addition, we have found that you can simply say, “That’s not how you pronounce [any name]” and Siri will go through the learning process.
In that phase, it will ask you to say the name then present a few options of how it thinks you said it. Once you choose an option, it will save and always (try to) correctly pronounce the name.