Hearing device and method of operating a hearing device

The method for operating a hearing device (1) having an adjustable transfer function (G) comprising M sub-functions (g1...gM), wherein M is an integer with M ‰¥ 1, and wherein said transfer function (G) describes how input audio signals (S1) generated by an input transducer unit (2) of said hearing device (1) relate to output audio signals (S2) to be fed to an output transducer unit (5) of said hearing device (1), comprises the steps of: - deriving said input audio signals (S1) from a current acoustic environment; and for each of said M sub-functions (g1,..., gM): - deriving, on the basis of said input audio signals (S1) and for each class of N classes (C1,...,CN) each of which describes a predetermined acoustic environment, a class similarity factor (p1;...;pN) indicative of the similarity of said current acoustic environment with the predetermined acoustic environment described by the respective class, wherein N is an integer with N ‰¥ 2; - deriving from N predetermined base parameter sets (B1/1,...,B1/N;...;BM/1,...,BM/N) assigned to the respective sub-function (g1;...;gM) and in dependence of said class similarity factors (p1,...,pN) an activity parameter set (a1;...;aM) for the respective sub-function (g1;...;gM), wherein each of said N base parameter sets (B1/1,...,B1/N;...;BM/1,...,BM/N) assigned to the respective sub-function (g1;...;gM) is assigned to a different class (C1;...;CN) of said N classes (C1,..., CN); - adjusting the respective sub-function (g1;...;gM) by means of said activity parameter set (a1;...; aM). It is suggested to use a time-averaged activity parameter set (a1*). An improved adaptation of the hearing device to a current acoustic environment can be achieved.