How to Control Your iPhone with Your Voice
If you have an iPhone 3GS or 4, you can boss around your music by using nothing but your voice. You can tell your iPhone to play certain music or even give you information about what's playing. Here are the voice-controlled commands you can give:
To play an album, an artist, or a playlist: Say "Play," and then say "album," "artist," or "playlist" and the name of the album, artist, or playlist, respectively. You can issue these voice commands at any time, except when you're on a phone call or having a FaceTime video chat. In other words, you don't need to have music playing for these voice commands to work.
To shuffle the current playlist: Say "Shuffle." This voice command works only if you're listening to a playlist.
To find out more about the song that's playing: Ask "What's playing?" "What song is this?" "Who sings this song?" or "Who is this song by?" Again, these commands work only if you're already listening to music.
To use Genius to play similar songs: Say "Genius," then "Play more like this" or "Play more songs like this." If your iPhone has no Genius playlists and you say "Genius," your iPhone will politely inform you that "Genius is not available." The same thing happens if you say, "Play more like this" or "Play more songs like this" when no song is playing.
And hey, because your iPod happens to be an iPhone, you won't look stupid talking to it!
Although controlling your iPod by speaking aloud works most of the time, in noisy environments, the iPhone may mishear your verbal request and start playing the wrong song or artist, or try to call someone on the phone. Using the wired headset helps.