There's an area of industrial drone/field recording music that has become a bit problematic in recent years by virtue of strong work done by some against which it's all but impossible not to measure others. If you're going to process on-site recordings and leaven them with any sort of tonal drone, grainy or smooth, you're up against prior music by Fennesz and dozens of accomplished musicians in that lineage.

Nilsen, who has worked with Stilluppsteypa and Philip Jeck, among others, walks down that path and constructs dark, vaguely threatening soundscapes that work perfectly well but is there something to set them apart? On the longer pieces, where ideas are able to develop, there are hints of that, as on the first track, "Gravity Station". About nine minutes in, an effective if routine desolate hum is interrupted and overlaid by a sound like suitcases being manhandled, a dull sliding and bumping in a claustrophobic environment. It's disturbing and ambiguous, a strong additional element that pushes the piece to an area relatively untrammeled. The three lengthier cuts on the disc tend to fare better, the dark ooze given time to seep into unexpected corners. Still, there's perhaps an excess of tonality in play here, maybe a nod toward listeners approaching this music from rock, which may impart a pinch too much sweetness for those preferring a more ruthless attack. The four shorter tracks fall victim to both this softening and to, necessarily, a lack of development, causing them to pass by like not so interesting snapshots in a slideshow.

If one is new to this area, The Invisible City might be just the gateway. If you've been before, much of the city might seem all too visible.