A modified energy detector is proposed as a predictor of human frequency‐ and amplitude‐discrimination performance. The model consists of an initial bandpass filter followed by a square‐law device and an integrator. The center frequency of the initial filter is assumed to be a random variable distributed over time. The predictions of the model for performance in two‐alternative forced‐choice frequency‐ and amplitude‐discrimination experiments are presented, together with data from human observers. While the model is able to predict the frequency and amplitude data very well, it is less successful with detection data.