9. The method of claim 1 , further comprising deriving the first neural network from the second neural network by: retaining hidden layers of the second neural network and parameters of the hidden layers of the second neural network; replacing an output layer of the second neural network that provides outputs corresponding to context-independent states with an expanded output layer; and training the expanded output layer to provide outputs corresponding to context-dependent states.
10. The method of claim 9 , wherein training the expanded output layer comprises adjusting parameters of the expanded output layer while maintaining the parameters of the hidden layers of the second neural network.