Ten minutes into the nearly 20-minute runtime of “Side A,” the opening track — the first half — of Brilliant Days, the new album by Michiru Aoyama, the music gets so quiet, the volume dips so near-thoroughly, that you might think the light bits of noise that linger are from tension on your headphone jack. Up until that moment, it has been all strings (guitar, though it could be mistaken for a synthesized simulation) and rustling (marbles? cash registers? leaves?), a sonic kaleidoscope of materials coming in and out of focus, in and out of interaction with each other, a soft tornado of simple sounds.
When the music recovers from that dip, when the second half of “Side A” is revealed as, in essence, a track unto itself, the vibe is heavier, the sounds deeper and the momentum at once more insistent and, yet, still suggested rather than explicit — less a matter of beats, more a matter of pulses. The music has moved from drone to atmospheric exotica, and it doesn’t let up on “Side B,” another nearly 20-minute escape into Aoyama’s considered exploration of melody and sound design.