An N-level quantizer on [a,b] with cell boundaries a·rᵏ where r = (b/a)^(1/N). The relative cell width w(x)/x is constant at ε = R·ln2/N (where R = log₂(b/a) is dynamic range in octaves), giving constant relative quantization error across all bins. Geometric midpoint codepoints: cₖ = a·r^(k+1/2).