While tuning corrects the pitch of your piano and places the strings' tension appropriately to form the musical scale, it does not factor in tonal colour, volume, and overall balance of the instrument. A piano technician can adjust the tonal quality and overall sound of your piano by voicing the hammers. A piano can be voiced to ensure notes are balanced across the entire keyboard. Depending on the client’s needs and wants different tonal adjustments can be made to create the desired sound quality achievable on your instrument.
A piano's tone changes over time, as hammers become worn down and the fibres more condensed, the harsher/brighter the sound becomes. Though voicing can often help, hammers may need to be filed or even replaced in some situations to correct this problem. No one piano sounds the same. A good technician will be able to highlight the good qualities of each instrument.