While taking a not-well-deserved study break last Sunday, I decided to use one of my favorite procrastination techniques and browse the “Exclusive First Listen” section of NPR’s music website, which allows viewers to listen to a handful of upcoming albums in their entirety. I felt guilty about procrastinating until I stumbled across an upcoming album by the jazz guitarist Mary Halvorson, titled “Saturn Sings.” I was especially excited to listen to an album by Halvorson because I had heard a lot of great things about her but had never actually heard her play. I was not disappointed. There are 10 tracks on “Saturn Sings,” and most feature Halvorson’s quintet, which consists of Jonathan Finlayson on trumpet, Jon Irabagon on alto saxophone, John Hébert on bass and Ches Smith on drums. A few tracks feature only Halvorson’s trio, with Hébert and Smith. While listening to the album’s first track, “Leak Over Six Five,” the first thing that struck me was Halvorson’s unique and exciting sound. that excitement stems from its unpredictability; Halvorson mixes clean and distorted guitar sounds, and at times uses so much distortion that she verges on Slash’s energy. She also liberally uses pitch bends, whammy bar effects and funky chord patterns. As a result of Halvorson’s use of dissonance, it is tempting to label her as a “free jazz” musician. Indeed, she studied with the avant-garde saxophonist and composer Anthony Braxton and has played in groups with edgy musicians like Braxton, saxophonist Tim Berne and drummer Tom Rainey. There are also a fair amount of more exploratory parts of “Saturn Sings” that illustrate Halvorson’s comfort in improvisatory settings. However, “Saturn Sings” is not a “free jazz” album. It is meticulously composed and many of its compositions employ catchy melodies rooted in diverse influences. There’s plenty of great improvisation on the album, but it only occurs within the confines of Halvorson’s well-structured compositions. On some compositions, the quintet begins the melody in unison and locks in with Smith’s ride cymbal pattern. Finlayson and Irabagon nail Halvorson’s tricky horn arrangements, often with the energy of a funk or salsa band. After the ensemble ends the melody, the song’s structure usually disintegrates as the musicians take more improvisational liberties. For instance, on the song “Sea Seizure,” Halvorson plays a melody that is at first reminiscent of an alternative rock song. Throughout the melody, Halvorson’s pulsating, distorted guitar rhythm and drummer Smith’s syncopated rock groove drive the ensemble. As the melody progresses, Halvorson uses hints of dissonance and Smith’s groove gradually becomes less obvious. After the ensemble finishes the melody, Halvorson takes a solo that quickly departs from the original theme and becomes increasingly chaotic. She uses dissonance, bent notes and unpredictable distortion and pushes Smith and bassist John Hébert to also play more explosively. However, the song’s form and groove become audible again once the quintet ends the solo section and restates the melody a final time. While Halvorson’s playing is heavily improvisatory, distinct and free at times, she should not be classified as another “free” player. She writes melodies that are tasteful and interesting, and her quintet complements these melodies through its thoughtful use of improvisation. But her quintet grooves especially hard after they end a solo section and begin to play a recognizable, though not totally straight-ahead melody. So, if the “free jazz” label scared you away the first time, definitely give Mary Halvorson’s work a second chance. You won’t be disappointed.