Fallback noise is one of the many details of the digitally reproduced acoustic piano sound. For added authenticity, fallback samples simulate the sound of the hammers falling back onto the felt after the piano keys are released.
Why Fallback Noise?
You don’t really want to hear the “thump” of the hammers on a grand piano. So why do software pianos in particular try so hard to reproduce that soft, muffled, woody-sounding noise? Well, this noise is as much a part of the piano sound as the key-off effect and string resonance. However, there is a reason why you need to adjust it separately in a digital piano sound, just like any other sound detail: Piano miking techniques, which can be simulated on a digital piano using the Piano Sound Editing function.