The method makes it possible in particular to determine the heartbeat of a person by means of a pulse measuring device (1). Light waves are generated by two light sources (5, 6) with a first wavelength (A1) which is sensitive to the pulse beat and the mov ement of the person, and with a second wavelength (?2) which is different from the first wavelength and is sensitive to the movement of the person. The light waves are transmitted in the direction of the skin of the person. The photodetector (7) detects the reflect ed light waves in order to provide electrical measurement signals. Thereafter, a calculation is made of at least one non-coherent power spectrum on the basis of a spectral coherence function ? which takes into account the dependence between the measurement sign als relating to the first wavelength and to the second wavelength by the formula SNC = (1-r2, sm where SAA is the average Fourier power spectrum of the measurement signals relating to the first wavelength of the sensed light waves, and where ?2 is between 0 and 1. Finally, the heartbeat Is determined on the basis of the non-coherent power spectrum. Figure 1
