A lot has changed for Joel and Benji Madden since they started playing music back in 1996, but with their fifth album due this summer, the twins have been trying to get back to the good old days.

"We started our band in a garage when we were 15," Benji said. "Good Charlotte's the fist band we've ever been in, and back then, critics didn't matter. There were no rules. There was no one we had to impress. Now we're just kind of like — we want to get back to that place where it's just like, 'I like that because I like it. I just love music because it's fun.' "

The new album, which will feature love ballads and deep lyrics, is appropriately titled Cardiology, which, Joel explained, "Is the branch of medicine that deals with diseases of the heart. So when you think about it — is there any real medicine when it comes to dealing with any feelings of the heart, whether it's love or hate or anger? Is there really any medicine for that? There really is nothing you can do for the conditions of the heart."

And while they might be "digging deep on the lyrics," don't expect Good Charlotte to get too soft. While Cardiology reflects their present lives, the brothers say it sounds a lot like breakthrough album The Young and the Hopeless, with straightforward music, big hooks and a lot of harmonies.

They have written about 40 songs for the album, all of which could appear on the final version, but they already have their favorites picked out: "Sex on the Radio," a rock song that tries to capture the essence of a woman's voice on the radio, and "Love Ain't Easy," which Benji says reminds him of the title track from the movie "That Thing You Do!"

Cardiology is expected to drop this summer, but in the meantime, Benji has been posting a series of acoustic covers of his favorite songs on the Good Charlotte site.