Railsback chart quantifies the gap between stretched piano tuning and equal temperament

Evidence

O. L. Railsback realized that most pianos were tuned this way and developed a graphic that reveals the difference between normal stretched piano tuning and an equal-tempered scale, in which the frequencies of successive notes are related by a constant ratio. He plotted the deviation between the stretched pitch of the notes and its nominal equal-tempered pitch in cents (figure 19.2). — Eric J. Heller, Why You Hear What You Hear- An…, 1826

Categorization

• DEFINE: The Railsback curve is named and defined as the deviation between real stretched piano tuning and the equal-tempered constant-ratio scale, measured in cents.