For Rachmaninov's Etudes-Tableaux Op.33, No.5, measures 42, 44, and 46, there are the notes supposed to be held as a voice suspended over the other notes. How would one keep the note alive and strong without having to play it ff (such a sudden contrast would be out of place in a section marked pp). For measure 42, the sustain would work fine, but in 44 if you do sustain you catch the other notes that aren't supposed to be suspended. Especially in 44 it creates a sort of smear over the rest of the measure that doesn't make for good listening. How would one isolate that upper voice and keep it strong when the sustain doesn't do the trick in all circumstances and the sound from the note fades too quickly after being struck?