We proposed previously a novel pitch-synchronous peak-amplitude (PS-PA) based feature extraction method, which achieved significant recognition accuracy for robust ASR [1]. It is well-known that an auditory neuron has pitch detection mechanism that can be useful for speech detection, and also peak-amplitudes in temporal pattern are robust to noise. In this paper, we conduct several experiments to find out relative contributions of pitch-synchronization (PS) and peakamplitudes (PA) on recognition accuracy of robust ASR. Experiments include methods with fixed and pitch-synchronous frame lengths, and that with traditional peak-amplitudes and pitch-synchronous peak-amplitudes. The experimental results show that both PS and PA have strong contributions towards robust ASR and the effect of PS is higher than that of PA.