If your instrument displays a lack of sensitivity or a decreased dynamic ranges, it's a candidate for regulation. If you notice that the keys are not level (some higher or lower than the rest), the touch is uneven or that the keys are sticking, the need for regulation is indicated.
Regulation is the adjustment of the mechanical aspects of a piano compensating for the effects of wear, the compacting and settling of cloth, felt, & buckskin, as well as dimensional changes in wood and wool parts due to changes in humidity. The action is comprised of over 9,000 parts which require adjustment to critical tolerances to be able to respond to a pianist's every command.
While tuning corrects the pitch of your piano, it is only one component of a complete maintenance program. Regulation attends to the touch and uniform responsiveness of your action. Regulation ensures that your instrument is capable of producing a wide dynamic range -- a critical factor, particularly in pianissimo passages.
All upright and grand pianos need
periodic regulation to perform their best. Frequency of regulation is dependent
upon amount of use, exposure to climatic changes, and the instrument's quality,
age and condition. New pianos may require regulation in their first year because
settling and compacting of parts sometimes necessitates adjustment.
No amount of practice can compensate for a poorly maintained action. Poor legato touch, chord playing where all notes of the chord don't speak clearly, a gradual loss of subtlety in phrasing and an inability to execute quick passages or note repetitions evenly may be the fault of the piano -- not the player.
Your piano is a major investment which deserves to be protected through regular servicing by a qualified technician. Properly maintained, your piano will sound its best and give you and your family a lifetime of enjoyment.