13. The speech recognition method of claim 12 , wherein the calculating the bidirectional language model scores comprises: selecting one of the forward and backward language models for each of the words in each of the generated word strings; and calculating the bidirectional language model scores of the generated word strings selectively using the forward and backward language models for each of the words in each of the generated word strings.
13. The speech recognition method of claim 12 , wherein the calculating the bidirectional language model scores comprises: selecting one of the forward and backward language models for each of the words in each of the generated word strings; and calculating the bidirectional language model scores of the generated word strings selectively using the forward and backward language models for each of the words in each of the generated word strings. 14. The speech recognition method of claim 13 , wherein the selecting one of the forward and backward language models comprises: calculating forward and backward language model scores of each of the words in each of the generated word strings using the forward and backward language models, respectively; and choosing whichever of the forward and backward language models produces a higher language model score for each of the words in each of the generated word strings.