Comparisons of the subjective loudness growth function and the objective evoked compound action potential (ECAP) amplitude growth function indicate that both functions are exponential in nature. This implies that a more accurate estimate of the ECAP threshold would be obtained using exponential regression of the amplitude growth function instead of the currently used linear regression. The perceptual threshold and the ECAP threshold seem to approach each other when the stimulation rate is lowered to reduce temporal summation effects. The effect of the stimulation rate on the perceptual threshold will have to be taken into account when trying to use the ECAP threshold for predicting the perceptual threshold.