What is pitch raising?

If your piano has not been tuned for a long time, the pitch may have dropped below the standard Concert Pitch (called A440). If that has happened, it will need additional tuning or “pitch raising” before it can be tuned and remain stable. Depending on the condition and service history of the piano, more than one pitch raise may be required before the piano can hold its tune, and some old pianos are incapable of supporting the string tension required to maintain an A440 concert pitch.