Just when a pitch adjustment is necessary depends upon how accurate the final tuning must be, and the size and quality of the piano. Any net change in a piano's string tension during tuning will distort the final result and reduce stability. Realistically, a pitch difference of a few percent can usually be accommodated successfully during tuning. For average situations, when a piano's pitch is noticeably different from that of other standard pitched instruments, a pitch correction procedure is necessary before tuning. Whenever exact pitch level is critical, such as in concert or recording instruments, any pitch deviation must be corrected before tuning.

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