Human and monkey differential sensitivity is compared for a wide variety of simple and complex auditory signals in order to determine how classic measures of pure tone frequency (ΔF), intensity (Δl) and temporal (ΔT) discrimination relate to the discrimination of more complex acoustic cues in human speech and monkey sounds. Sensitivity is compared for pure tones, vowels, place-of-articulation contrasts, liquids, glides, English and Spanish VOT contrasts, as well as to a monkey coo call contrast based on the temporal position of a pitch peak. The data indicate that ΔF does not accurately predict the relative sensitivity of humans and monkeys to spectral cues in complex sounds. On the other hand, there is a good correspondence for ΔT in simple and complex sounds. Some aspects of monkey discrimination of ΔF and VOT indicate parallels with the human developmental data.