Bayesian Approach
• Assume a language model P(words)
• Want P(words|signal).
• If we had P(signal|words), we could compute the
words that maximize P(words|signal).  How?
• If the signal gave us a list of phones, we could do
this, but we can't.
• The best we can do at this point is to compute
P(words|phones).  Then we need P(phones|signal).
• For this, a hidden Markov model (HMM) is
used.