On cepstral and all-pole based spectral envelope modeling with unknown model order

In this work, we investigate spectral envelope estimation for harmonic signals. We address the issue of model order selection and propose to make use of the fact that the spectral envelope is sampled by means of the harmonic structure of the signal in order to derive upper bounds for the estimator order. An experimental study is performed using synthetic test signals with various fundamental frequencies and different model structures to evaluate the performance of the envelope models. Experimental results confirm the relation between optimal model order and fundamental frequency.