Quantitative measurements are reported on the intensities of subjective tones produced within the human ear under single and dual tone excitation. The measurements are made by the exploring tone method. The even and odd subjective harmonics show some differences, indicating that the organ, or set of organs, producing non‐linearity is not the same as the source of asymmetry. The intensities at which these two distorting effects first appear are not the same. The subjective summation tones are, in general, weaker than the corresponding difference tones of the same order. These differences are to be expected if auditory masking is a process occurring within the hearing mechanism.