If commitment is the measure, then Max Richter’s deservedly well-received Sleep, his eight-hour sonic paean to slumber, has one major peer this year. That would be Taylor Deupree’s ongoing 2015 Studio Diary. At about 70 tracks so far, the diary is only half the length — just under four hours — of Richter’s Sleep, but like Richter’s work, Deupree’s balances length with lightness, intensity with a soft touch. The October 12 entry, “a piano in autumn,” is little more than a digital piano refracted over the course of a minute and a half, as minor artifacts of tone are extended and warped while the full, simple piece continues. It’s Satie on pause, Feldman heard from a right angle. It’s a work composed entirely of grace notes.