Four years after releasing Lullabies & Nightmares, his fascinating 2013 debut for Kranky, Michigan-based artist Justin Walter returned to the label with Unseen Forces. As with his previous solo work, Walter creates otherworldly sounds using the EVI (Electronic Valve Instrument), a rare wind-controlled analog synthesizer often associated with new age music and jazz fusion. He processes and loops the sounds through a bench full of electronics, in addition to playing trumpet and piano. At times, the EVI's tones are abrasive and distorted, yet there's an amorphous glaze to them, and they rarely feel harsh. The music was created spontaneously, and it doesn't seem like it could've been composed -- these sound like transmissions from dreams rather than properly written songs. As a whole, Unseen Forces is softer, subtler, and less immediate than its predecessor. This is partially due to the fact that drummer Quin Kirchner is absent this time around, but even still, there isn't as much of a pulsating shimmer to these pieces. At first, it seems easier to categorize the album as ambient music, especially given how opener "1001" builds up layers of drifting, droning sounds, gradually becoming more immersive. The album's title track begins with sustained piano notes, which form slow, rippling patterns, accompanied by solemn trumpet. "Sixty" is where things start to get more paranormal, as the electronic textures become grainier and shift more rapidly. The sounds emitting from the EVI are noisier, yet there's still a calm drift to them; somehow the music sounds both relaxed and alarmed. "It's Not What You Think" starts off with sparse, wobbly EVI notes before gaining a gently reverberating rhythmic pulse that suggests an E2-E4-inspired Detroit techno track but never lands on a beat. Instead, it floats and sparkles in midair while Walter coaxes more warped tones from the EVI. This is as bright and joyous as the album gets, however, as subsequent pieces are darker and more haunted. "Soft Illness" is a blast of Lawrence English-like power ambient, with thick, billowing storm clouds of fuzz and humming bass tones. Unseen Forces may seem more challenging than Walter's previous album, but it's just as captivating, and most certainly worth delving into.