What is raising pitch?
When a piano has been neglected for several years, the pitch of the piano (normally A440 cycles per second) can decrease from the wire (strings) being under constant tension and not tuned. In order for the tuning to be fairly stable after such neglect, the pitch must be set first by bringing it up to A440 after which it can be tuned. If the pitch raise was not done, it would not be stable nor would it sound good. In fact it may even sound worse than it did before it was tuned, therefore, raising the pitch is essential for stability in the tuning process.
