The automatic parametrization of the first derivative of glottal flow is studied. Representatives of the two types of methods used most often for parametrization were tested and compared. The chosen representatives are all based on the Liljencrants–Fant model. As numerous tests were needed for a detailed comparison of the methods, a novel evaluation procedure is used which consists of the following stages: (1) use the Liljencrants–Fant model to generate synthetic flow pulses; (2) estimate voice source parameters for these synthetic flow pulses; and (3) calculate the errors by comparing the estimated values with the input values of the parameters. This evaluation procedure revealed that in order to reduce the average error in the estimated voice source parameters, the estimation methods should be able to estimate noninteger values of these parameters. The proposed evaluation method was also used to study the influence of low-pass filtering on the estimated voice source parameters. It turned out that low-pass filtering causes an error in all estimated voice source parameters. On average, the smallest errors were found for a parametrization method in which a voice source model is fitted to the flow derivative, and in which the voice source model is low-pass filtered with the same filter as the flow derivative.