1. A method for classifying a background noise contained in an audio signal, the method comprising: extracting from the audio signal a background noise signal, the background noise signal being a noise signal; utilizing a computer processor to calculate a first parameter relating to a time evolution of the noise signal, and a second parameter relating to a frequency spectrum of the noise signal, the first parameter being a time indicator and the second parameter being a frequency indicator; and classifying the background noise contained in the audio signal amongst a predefined set of background noise classes, as a function of values of the calculated time indicator and frequency indicator.