Till now I know that- first the speech is converted frames and feature vectors are calculated for each frame using MFCC. And while training the Acoustic model- HMM model is generate for each phoneme and each such HMM model has 3 states representing starting, middle and ending of context dependent phonemes. Also each of these states gives the likelihood probability for a given observation sequence using GMM.
My question is:
What is this observation sequence taken in GMM, is it the feature vector of a single MFCC frame or a sequence of MFCC frames ? If not then what exactly are these observation sequences and how are they related to MFCC feature vectors.