Classical objective criteria evaluate speech quality using one quantity which embed all possible kind of degradation. For speech denoising applications, there is a great need to determine with accuracy the kind of the degradation (residual background noise, speech distortion or both). In this work, we propose two perceptual bounds UBPE and LBPE defining regions where original and denoised signals are perceptually equivalent or different. Next, two quantitative criteria PSANR and PSADR are developed to quantify separately the two kinds of degradation. Some simulation results for speech denoising using different approaches show the usefulness of proposed criteria.