A method of training an algorithm for optimizing intelligibility of speech components of a sound signal in hearing aids, headsets, etc., comprises a) providing a first database comprising a multitude of predefined time segments of first electric input signals representing sound and corresponding measured speech intelligibilities; b) determining optimized first parameters of a first algorithm by optimizing it with said predefined time segments and said corresponding measured speech intelligibilities, the first algorithm providing corresponding predicted speech intelligibilities; c) providing a second database comprising a multitude of time segments of second electric input signals representing sound, d) determining optimized second parameters of a second algorithm by optimizing it with said multitude of time segments, said second algorithm being configured to provide processed second electric input signals exhibiting respective predicted speech intelligibilities estimated by said first algorithm, said optimizing being conducted under a constraint of maximizing said predicted speech intelligibility.