1. A method for processing signals in a pulse oximeter to determine oxygen saturation and pulse rate, comprising: receiving waveforms corresponding to two different wavelengths of light from a patient; ensemble averaging the waveforms in a first ensemble averager; calculating a pulse rate based on an output of the first ensemble averager; normalizing the waveforms to produce normalized waveforms; ensemble averaging the normalized waveforms in a second ensemble averager; and calculating an oxygen saturation based on an output of the second ensemble averager.