Hidden Markov Model Toolkit (HTK)

The Hidden Markov Model Toolkit (HTK) is a portable toolkit for building and manipulating hidden Markov models. HTK is primarily used for speech recognition research, although it has also been used for other applications of HMMs such as character recognition, DNA sequencing and protein modelling. Siri uses speech recognition technology, and HTK is a fundamental toolkit used in the development of many speech recognition systems, including those based on hidden Markov models.