7. The computer readable storage medium of claim 6 , wherein the method further comprises: training the selected one or more N-gram entries using all the recognition results and adding, to a base N-gram language model, the one or more N-gram entries and probabilities obtained as a result of the training.
6. A non-transitory, computer readable storage medium having instructions stored thereon that, when executed by a computer, implement a training method for an N-gram language model, the method comprising: reading recognition results obtained as a result of speech recognition of speech data; acquiring a reliability for each of the read recognition results; referring to each recognition result's acquired reliability to select a subset of one or more N-gram entries based upon their respective reliabilities; and training the N-gram language model for one of more entries of the subset of N-gram entries using all recognition results, wherein the processing device is further configured to select each of the N-gram entries, whose sum of a first number of appearances in a first corpus as a set of all the recognition results and a second number of appearances in a second corpus as a subset of the recognition results with the reliability higher than or equal to a predetermined threshold value exceeds a predetermined number of times.