1. A method for performing unsupervised speaker adaptations comprising: identifying a configurable value N representing a maximum amount of frames of feature vectors extracted from an utterance to be used when generating a transformation for the utterance regardless of utterance length; caching N amount frames of feature vectors extracted from the utterance for unsupervised speaker adaptation purposes; creating a transformation from the cache including N amount frames of feature vectors of the utterance; and applying the created transformation during an unsupervised speaker adaptation process.