 Pure tones have a clear pitch, but complex sounds such as speech and music typically have intense peaks at many different frequencies.Nevertheless, by establishing a fixed reference point in the frequency function of a complex sound, and then observing the movement of this reference point as the function translates, one can generate a meaningful pitch contour consistent with human experience.For example, the vowel "e" has two primary formants, one peaking between 280 and 530 Hz and one between 1760 and 3500 Hz.