A method for comparing a first audio data source with a plurality of audio data sources, wherein the first audio data source has an utterance spoken by a first person and the plurality of audio data sources have the same utterance spoken by a second person. The method includes performing a speech recognition function on the first audio data source to isolate at least one element of the first audio data source. The method also includes comparing the isolated element with a corresponding element in the plurality of audio data sources and determining whether the utterance spoken by the first person contained an error based on the comparison.