Semitones are logarithmically equal steps, not linear ones

Evidence

On the circle, each equal-tempered semitone interval progresses 1/12 of the way around, exactly. On the line, progression of exactly 1/12 of the distance from 1 to the octave at 2 (keeping in mind that both the circle and the line measure the logarithm of frequencies) means a factor of 21/12 = 1.05946… from one note to the next. — Eric J. Heller, Why You Hear What You Hear- An…, 2399

Categorization

• XREF: Connects to chapter 19’s Railsback effect mention and to the book’s recurring theme that musical pitch is best plotted logarithmically.