1. A hearing aid comprising at least one microphone, a signal processing means and an output transducer, said signal processing means being adapted to receive an audio signal from the microphone, wherein said signal processing means has a table of signal processing parameters mapped to a set of stored noise classes and noise levels, means for classifying a background noise of the audio signal, means for estimating a level of background noise in the audio signal, and means for retrieving, from the table, a set of signal processing parameters according to the classification and the level of background noise and processing the audio signal according to the retrieved set of signal processing parameters to produce a signal to the output transducer.