In the last decade, there has been considerable interest in digital music services that display the lyrics of songs that are synchronized with their audio. As a recent example, Sound Hound provided a live-lyrics feature using an audio fingerprint technique, with known time stamps for alignment. Although some well-known hit songs already have lyric time stamps within existing karaoke databases, more than a hundred million numbers, including new, unpopular songs YouTube cover songs, and live recordings may not. An automatic lyrics-to-audio alignment system could reduce the huge amount of time and labor required to manually construct such time stamps. Not limited to the application above, it could also be used as a front end for various purposes in content-based music information retrieval (MIR) involving lyrical rhymes and emotions.