Even after your piano is tuned, does it sound different than when you purchased it?
The fact is that it does. The sound in a piano is generated by felt-covered hammers striking the strings. As the piano is played, and with repeated blows against the strings, the hammers begin to develop grooves at the point of contact, and the felt just beneath the surface becomes more tightly packed. This tendency causes the piano to sound “brighter,” and can be compared to the difference in sounds caused by a felt mallet and a wooden stick striking a cymbal. The same concept applies to your piano’s hammers: the softer the material of the striker, the softer the sound.
“Voicing” is the process of re-shaping and manipulating the consistency of the hammers felt, using various specialize tools, to achieve the desired tone quality. This is an entirely separate process from tuning, and is generally done only by more experienced piano technicians.