Abstract: The present disclosure relates to systems and methods for probabilistically estimating an individual's pulse rate in the presence of nontrivial noise spectra. In one implementation, the method may include receiving a set of signals from a set of sensors associated with the device, the set of signals including a photoplethysmographic (PPG) signal obtained from the individual; transforming the PPG signal to the frequency domain; applying a band-pass filter to the transformed signal to generate a filtered signal; identifying one or more peaks in the filtered signal; generating a set of one or more sample classifiers for each peak in the set of one or more peaks; and comparing the set of sample classifiers to a set of library classifiers included in a learning library. Each library classifier is associated with a classification coefficient reflecting a degree of correlation between the library classifier and a known pulse rate profile.