The just‐noticeable‐difference in frequency (jndf) for complex signals with triangular spectral envelopes is found to depend on the envelope slope. For shallow slopes (<140 dB/oct), jndfincreases with decreasing slope. Addition of noise also impairs frequency discrimination within a region of about 20 dB above masked threshold. This is found for both maskers used: a wideband noise and a narrow‐band masker which is below the signal in frequency. When wideband noise is used, frequency discrimination of complex signals with shallow slopes deteriorates more rapidly with decreasing signal‐to‐noise ratio than it does when the signals have steep spectral slopes.