There isn't one. It's an engineering solution that just happens to work pretty often in ASR.
Complex P(W)'s are almost certainly fit by MLE. The models used are super complex, so MLE is often the only practical estimate. There are MaxEnt and Bayes methods, but I think generally people trade computational tractability of enormous models which wouldn't gain much from prior information because there's just so much data available.
Complex P(W)'s are almost certainly fit by MLE. The models used are super complex, so MLE is often the only practical estimate. There are MaxEnt and Bayes methods, but I think generally people trade computational tractability of enormous models which wouldn't gain much from prior information because there's just so much data available.
The best data is more data.