The piece I am learning has a highly repetitive melody line for the left hand (always the same 4 notes, but not all at once), and I want to apply "sustain" for them, while not applying sustain for the more complex melody played with the right hand at the same time.
Looks like a good case for the middle piano pedal, just that there is no time moment when all four keys on the left are depressed down. Sustain "locks" for me only for the keys that were down when I press the middle pedal.
Ok, then I press the keys slowly at the beginning of the piece (slowly enough to produce no sound), then the middle pedal, and keep the middle pedal down until the end of the piece. But this is my own invention.
How is the middle pedal supposed to be used? Can it be applied for the melody line, or must one play a chord first when all relevant piano keys are pressed, giving you a chance to press the pedal at this time?