A new determination was made of the way in which differential sensitivity for frequency varies both with loudness level (up to 30 phons) mud with frequency (60–4000 cps). The effect of loudness level is independent of frequency, but sensitivity (in terms of cycles discriminable) improves continuously as frequency decreases. These results are in sharp contrast with those of the most widely‐quoted study in the field, and call for some reinterpretation of the relation between pitchDLs and such psycho‐acoustic phenomena as the pitch scale, the masking of tones by noise, and frequency localization within the auditory system.