19. An apparatus for normalizing input data of an acoustic model, the apparatus comprising: a window extractor configured to extract windows of frame data to be input to the acoustic model from frame data of a speech to be recognized; and a normalizer configured to normalize the frame data to be input to the acoustic model based on results of a determination that an amount of frame data to enable speech recognition is determined sufficient.
21. The apparatus of claim 19 , wherein the normalizer is further configured to normalize the frame data based on frames of all of the extracted windows from a first extracted window to a current extracted window and frames of training data.