Existing studies in classification of phonation types in singing use voice source features and Mel-frequency cepstral coefficients (MFCCs) showing poor performance due to high pitch in singing. In this study, high-resolution spectra obtained using the zero-time windowing (ZTW) method is utilized to capture the effect of voice excitation. ZTW does not call for computing the source-filter decomposition (which is needed by many voice source features) which makes it robust to high pitch. For the classification, the study proposes extracting MFCCs from the ZTW spectrum. The results show that the proposed features give a clear improvement in classification accuracy compared to the existing features.