On Tegan and Sara's fourth album, the Quin sisters add synthesizers to their hooky pop-punk. For the most part, the new instruments lend a New Wave tinge to songs like “You Wouldn't Like Me” and the upbeat “Speak Slow,” but a few of Sara's songs push into totally new melodic territory, as on the title track's hypnotic pulse, and “Walking With a Ghost,” their first breakout hit, which would be covered by The White Stripes. So Jealous is the first of the bold musical leaps that would eventually define the twins' career.