Fig. 2

Numerical verification of the proposed recursive least squares estimation (RLSE) method with an exponential forgetting factor to extract physiological noises: a Expected HbO, b cardiac, c respiratory, d Mayer wave, and e white noise with zero mean and standard deviation of 10⁻⁴, f mixed signal of a–e; a^* a comparison of f and the estimated signal of a; b^*–d^* the estimated signals of b–d; b^**–d^** the spectra of b^*–d^*, respectively