The algorithm compares the signal, after it has been through the coder and decoder process, with the original signal. If the input and output are identical the algorithm is designed to produce a perfect score of 0. Although PSQM does not have a direct correlation to MOS, the subjective quality is inferred from the objective quality. That is, if a person listens to a speech sample that has a PSQM value of 2, that person would think the quality was worse than a speech sample that had a PSQM value of 1. Input Signal A system that will assess the quality of speech must allow you to transmit different voices.
Artificial speech has advantages in reduced redundancy and talker independence.
The algorithm takes the PSQM value and does post processing on the value, based on PSQM and signal power. The major problem with PSQM is the alignment of the output signal with the input signal. The delay through the network is unknown. For a typical IP network it could be between 30 ms and 300 ms. If they are not properly aligned, the output will be invalid.