1. A method for discriminating between at least two classes of events, the method comprising: receiving a set of frames including an input signal; determining at least two different feature vectors for each of the frames; classifying the at least two different feature vectors using respective sets of preclassifiers trained for the at least two classes of events; determining values for at least one weighting factor based on outputs of the preclassifiers for each of the frames; calculating a combined feature vector for each of the frames by applying the at least one weighting factor to the at least two different feature vectors; and classifying the combined feature vector using a set of classifiers trained for the at least two classes of events.