A new spectral envelope estimation procedure is proposed to recover details beyond band limitation imposed by the Shannon's sampling theory when interpreting periodic excitation of voiced sounds as the sampling operation in the frequency domain. The proposed procedure is a hybrid of STRAIGHT, a FO-adaptive spectral envelope estimation and the auto regressive model parameter estimation. Wavelet analyses of these spectral models on the frequency domain enabled objective evaluation of this recovery procedure. The proposed procedure provides better speech quality especially when parameter manipulation is introduced.