Tinnitus is a horrible experience, but Ephemeral Exhibits, Starkey's second album for Planet Mu, seems like a quest to summon a more benign version. Dubstep's low-end having long been conquered, the Philadelphia producer turns his attention to the highs, slathering his tracks in squealing synth riffs that twitch like live wires. "Pictures" piles on shivery synthesizer leads — harpsichords, flutes and triumphant G-funk whistles that come together in a spine-tingling buzz — while the almost identical riffs of "Pressure" and "Escape" scream out like alarm bells. Zipping around drunken drum breaks and lurching bass lines, Starkey's airborne melodies feel like loosed Bungee cords snapping to and fro. Accordingly, Ephemeral Exhibits is full shifts both swift and subtle: "Escape" begins with xylophones and meditative Mellotron before slipping into battle mode, while "Dark Alley" flips between ecstatic R&B, mutant crunk and breakbeat hardcore. And the whole album, while overwhelmingly heavy, goes down easier in one sitting thanks to "Spacewalk" and "Miracles" — slower, softer cuts with a melancholic, nostalgic bent. Like Rustie, Zomby and his labelmates Neil Landstrumm and Distance, Starkey is taking dubstep in a wildly creative direction where nearly everything — rhythm, sound design, balance, proportion — is up for…