Left Piano Pedal ‘una corda’
What does the left pedal do on a piano? A grand piano shifts the hammers to the right side of the strings so that instead of hitting three strings, the hammers hit only two strings, making the sound quieter.
On an upright piano, the una corda pedal moves the hammers closer to the strings to make the distance closer so the sound is quieter.
Middle Piano Pedal ‘Sostenudo’ or ‘practise pedal.’
The middle pedal can either be a practise pedal or a sostenuto pedal. If it is a practise pedal, it will produce an even quieter sound than the left pedal. It makes it quieter by moving a thick piece of felt between the hammers and strings to soften the sound.
If the middle pedal is a sostenuto pedal although similar to a sustain pedal in effect, unlike the sustain pedal, it holds only the notes being activated only when the pedal is depressed The sostenuto pedal acts as a discerning damper. It sustains only the notes that are depressed when the pedal is activated. Any keys pressed after the pedal is down are not affected, meaning the sustain effect can be produced without making a blurred sound.