A method for adapting signal processing parameters of a hearing instrument of a hearing system. A number of acoustic indicators (IndA) for a temporary environmental situation of a user of the hearing instrument is ascertained from an input signal generated by a transducer. A first sensor ascertains a number of peripheral indicators (IndP) for the existing temporary environmental situation. Based on the acoustic and peripheral indicators (IndA, IndP) the system determines whether the existing temporary environmental situation falls into a known class of temporary environmental situations. If it does not, a new class is defined with the respective ascertained acoustic and peripheral indicator(s) (IndA, IndP), and the plurality of signal processing parameters are assigned a corresponding plurality of parameter values, according to which the first input signal is to be processed to form the output signal upon the future existence of a temporary environmental situation from the new class.