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Datum der letzten Prüfungsleistung: 13.09.2010 State-of-the-art automatic speech recognition (ASR) systems can achieve very low word error rates (WERs) of below 5 % on data recorded with headsets. However, in many sit-uations such as ASR at meetings or in the car, far field microphones on the table, walls or devices such as laptops are preferable to microphones that have to be worn close to the user’s mouths. Unfortunately, the distance between speakers and microphones intro-duces significant noise and reverberation, and as a consequence the WERs of current ASR systems on this data tend to be unacceptably high (30-50 % upwards). The use of a micro-phone array, i.e. several microphones, can alleviate the problem somewhat by performing spatial filtering: beamforming techniques combine the sensors ’ output in a way that fo-cuses the processing on a particular direction. Assuming that the signal of interest comes from a different direction than the noise, this can improve the signal quality and reduce the WER by filtering out sounds coming from non-relevant directions. Historically, array processing techniques developed from research on non-speech data, e.g. in the fields o