The objective of this work is to develop and study the robustness of the zero frequency resonator (ZFR) based method for extraction of the fundamental frequency (F0) of speech signals. The proposed ZFR method for estimating F0 consists of zero frequency filtering of the Hilbert envelope (HE) of the linear prediction (LP) residual of speech signal, followed by short-term spectrum analysis of the filtered output. The robustness of the proposed method is tested using speech signals collected in practical environments like distant, reverberant, telephone, mobile and multispeaker. Experimental results show that the proposed ZFR method estimates F0 in majority of the cases. © 2011 IEEE.