Sometimes, a jazz listener needs a wake-up call. Step away from the mainstream. Shut down the catchy tunes. Turn toward something a bit more abstract – the spirit of improvisation. The Andrew Rathbun Quartet delivers the latter with Numbers and Letters (SteepleChase Music, 2014).

The group consists or Rathbun, saxophones and voice; Phil Markowitz, piano; Jay Anderson, bass; and Bill Stewart, drums. Trumpeter Taylor Haskins visits for one track.

The set starts with the brooding “Bad Call.” Markowitz lays down an ominous piano groove. Rathbun brings in the sax. The pair engages in some rapid-fire combinations. At times, it’s as if each of the four players is in his own zone, only occasionally locking in as a unit. Group play is more evident when the theme, if one can be discerned, ends and the fun begins. Bass and drums are fully in support of the piano and sax during their middle solos.

“Playpen” is a more melodic piece. But like the other songs in this set, it allows plenty of freedom. The title is apt, as Rathbun and the gang exude a sense of let’s enjoy ourselves, and you can come play with us. The parts of Anderson and Stewart are subtle yet effective.

With music like this, it’s easy to forget that songs are actually written and presume that the artists just play whatever they feel. But songs must have a foundation, and Rathbun gives the music just enough foundation so that each structure holds together. Beyond that, however, it’s free expression – plain and simple. Stewart gets to stretch out more during the fade.

Rathbun has released a dozen album as a leader and built an extensive discography as sideman to such acts as Dave Liebman, Eddie Gomez, Luciana Souza and others. Born in Toronto, Rathbun spent the majority of his career in Brooklyn before becoming professor of saxophone in the Jazz Studies department at Western Michigan University.

Numbers and Letters is a stark reminder that jazz, at its roots, is creativity personified.