Time-inhomogeneous hidden Bernoulli model (TI-HBM) is an alternative to hidden Markov model (HMM) for automatic speech recognition.
This difference leads to elimination of dynamic programming at state-level in TI-HBM decoding process.
Thus, the computational complexity of TI-HBM for probability evaluation and state estimation is
are number of states and observation sequence length respectively).
The TI-HBM is able to model acoustic-unit duration (e.g. phone/word duration) by using a built-in parameter named survival probability.