1. A method for classifying at least one audio signal into at least one audio class, the method comprising the steps of: analyzing said audio signal to extract at least one predetermined audio feature; performing a frequency analysis on a set of values of said extracted predetermined audio feature at different time instances resulting in a power spectrum of said extracted predetermined audio feature; deriving at least one further audio feature representing a temporal behavior of said extracted predetermined audio feature by parameterizing said power spectrum, wherein parameterizing said power spectrum comprises (a) summarizing a frequency axis of the power spectrum by summing energy within at least one predetermined frequency band and (b) dividing (b)(i) the summed energy within the at least one predetermined frequency band by (b)(ii) an average of subsequent values alone of said extracted predetermined audio feature, not including preceding values, to (c) yield a relative modulation depth representing an amount of envelope modulation in the at least one predetermined frequency band; and classifying said audio signal based on said further audio feature.