Basic Algorithm

  • Time-synchronous
  • At each frame, evaluate all transitions
  • Make the 'best' transition
  • In the end, backtrack to get the best path

  • Viterbi Beam Search

  • Prune hypotheses outside beam

  • Advantages

  • Hypothesis comparison is direct

  • Limitations

  • State space is very large even for moderate-size applications
  • Moderate vocabulary sizes
  • Word-internal triphones
  • Bigram language model