 What is the argument against the periodicity theory of pitch? Compare an argument against reflectance physicalism about color. Reflectance physicalism identifies each hue with a class of reflectances. Periodicity physicalism identifies each pitch with a fundamental frequency. In both cases, each determinate sensible feature is identified with a determinate physical property. In the color case, it is objected that reflectance classes do not bear the relations to each other that the colors bear. In the pitch case, the frequencies do not bear the relations to each other that the pitches bear. Thus, if the relational features among a class of sensible qualities are essential to them, an account that does not accurately capture those relations fails. Frequencies, according to this line of argument, do not stand in the relations essential to pitch.