Seven years and a couple of theatrical projects and movie soundtracks after the masterful Bone Machine, Tom Waits returned with Mule Variations, a longer (16 tracks, 71 minutes) collection of songs that kept the rough-hewn feel of its predecessor, but also looked backward to his ’80s work. “Get Behind The Mule” is a sonic companion to “Gun Street Girl” from Rain Dogs, and the album closer, “Come On Up To The House,” recalls that album’s “Anywhere I Lay My Head.” But this isn’t a mere rehash — “What’s He Building In There?” is an eerie poetic interlude, and “Cold Water” is a harsh, noisy blues written from the perspective of a homeless man and played on a seriously cranked-up electric guitar. This album’s peaks are pretty high, but it drifts into forgettability a few times too often to make it one of his classics.