Frequency‐discrimination performance is measured as a function of the ratio of signal energy to noise‐power density (ε‐η0) for several values of frequency separation at 250, 1000, and 4000 cps. Discrimination performance at all frequencies and all frequency separations increases with increasing ε‐η0until ε‐η0reaches 40 dB. No further increase in performance was apparent with a further increase of 40 dB in ε‐η0.