In the fourth installment of Keith Berry’s Viable Systems series, the composer is once again orchestrating comforting soundscapes that drift on open aural seas. “Tropical Sediments” loses track of space and time, adrift on the open ocean into a vast unknown. Drenched in sweeping reverb, “Vapid Bucolia” sits in a pocket of melancholic lament. Scouting the next peak on the horizon, gauzy synths seep into every pore like a passive virus, coaxing you to continue the journey forward. Sunrise beckons on “Gliders” as gleaming sonic surfaces reflect light into a prismatic display. Berry extracts warm, gentle tones while deep bass pads and sparse guitar plucks act as guideposts. Viable Systems 4 is cool to the touch, but that glossy exterior shrouds an engaging and sympathetic embrace. Berry’s explorations always tap into auditory dimensions meant for traveling. Viable Systems 4 is another beautiful chapter in this continually unfolding story.