Patent US 3,947,638

A pitch analyzer is described which extracts, on a real-time or pipeline is, the pitch information from a speech signal. The analyzer converts the speech signal to a digital signal, shifts it into a delay line tapped at logarithmic intervals and constructs a measure of merit for each of many possible pitch periods. These measures are periodically transferred to a processor which combines them in a prescribed manner with previous information to select the one most-likely current value of pitch. Provision is also made, when the application warrants it, to select the best pitch value, with a delay of several frames, based on current information.