Abstract: Two experiments have been carri-d out to explore the interaction phenomena. It is shown that 1) The intrinsic fundamental frequency of vowels is also found in Chinese, 2) The difference of intrinsic fundamental frequency between high and low vowels are related to the pitch level and a linear relationship was found in a certain dynamic range of register beyond that nonlinear relation will appear, 3) Speech efforts influence not only the F₀ but also the F₁-F₂ pattern of vowels.