1. A processor implemented method for speech recognition of a speech signal comprising: within a processor: providing at least one codebook comprising codebook entries, in particular, multivariate Gaussians of feature vectors, that are frequency weighted; and processing the speech signal for speech recognition comprising: extracting at least one feature vector from the speech signal and matching the feature vector with the entries of the codebook; providing at least one additional codebook comprising codebook entries, in particular, multivariate Gaussians of feature vectors, without frequency weights; determining whether the speech signal corresponds to an utterance of a native speaker or to an utterance of a non-native speaker; and if it is determined that the speech signal corresponds to the utterance of a native speaker, using the at least one additional codebook comprising codebook entries without frequency weights for the speech recognition; or if it is determined that the speech signal corresponds to the utterance of a non-native speaker, using the at least one codebook comprising codebook entries that are frequency weighted for the speech recognition.