 Now consider the case of pitch. Are there pitch metamers? Some sounds with very different spectral frequency profiles match in pitch. A simple sinusoidal tone at a given frequency matches the pitch of each complex tone with that fundamental frequency (even those that lack a constituent at the fundamental). But, again, the case of pitch differs from the case of color. For each matching pitch, a single natural property does unify the class. The tones all share a fundamental frequency.