no single ideal PDA, so a variety of algorithms exist, most falling broadly into the classes given below.
[1] A PDA typically estimates the period of a quasiperiodic signal, then inverts that value to give the frequency.
However, this does not work well with complicated waveforms which are composed of multiple sine waves with differing periods or noisy data.
Then, among the candidates estimated from the two domains, a final pitch track can be computed using dynamic programming.
This means that in order to detect a fundamental frequency of 40 Hz, at least 50 milliseconds (ms) of the speech signal must be analyzed.