This paper studies the problem of single-channel noise reduction in the time domain. Based on some orthogonal decomposition developed recently and the squared Pearson correlation coefficient (SPCC), several noise reduction filters are derived. We will show that the optimization of the SPCC leads to the Wiener, minimum variance distortionless response (MVDR), minimum noise (MN), minimum uncorrelated speech and noise (MUSN), and linearly constrained minimum variance (LCMV) filters. We also compare the Wiener and MVDR filters derived from the SPCC to their counterparts derived from the mean-square error (MSE) criterion. Simulations are provided to illustrate the performance of all the deduced noise reduction filters.