In this study, we propose and compare two probabilistic models for online pitch tracking: Hidden Markov Model (HMM) and Change Point Model (CPM). As opposed to the past research which has mainly focused on developing generic, instrument-independent pitch tracking methods, our models are instrument-specific and can be optimized to fit a certain musical instrument. In our models, it is presumed that each musical note has a certain characteristic spectral shape which we call the spectral template. The generative models are constructed in such a way that each time slice of the audio spectra is...