1. A method for speech signal processing, comprising: detecting a speech signal by more than one microphone to obtain microphone signals; processing the microphone signals with a beamformer to obtain a beamformed signal; and post-filtering the beamformed signal by a post-filter that employs adaptable filter weights to obtain an enhanced beamformed signal, where the post-filter adapts the filter weights with previously learned filter weights, where the learned filter weights are obtained by supervised learning, where the supervised learning comprises the steps of: generating sample signals by superimposing a wanted signal contribution associated with the more than one microphone and a noise contribution for each of the sample signals; inputting the sample signals, each comprising a wanted signal contribution and a noise contribution, into a beamforming means to obtain beamformed sample signals; and training filter weights for the post-filterer such that beamformed sample signals filtered by a filter updating module use the trained filter weights to approximate the wanted signal contributions of the sample signals.