Digital signalling offers improvements in speech quality and very high levels of security.

EVRC provides excellent speech quality using variable rate coding with 3 possible rates, 8.55, 4.0 and 0.8 kbit/s.

Underwater, the speech quality would be much better.

This lower complexity, however, bears the cost of marginally reduced speech quality.

The lowest bit rate providing excellent speech quality in a clean environment is 12.65 kbit/s.

Its speech quality is high, but older networks will have to be upgraded to support a wide band codec.

It was later replaced with EVRC since it provides better speech quality with fewer bits.

P.863 is an ITU-T Standard that covers a model to predict speech quality by means of digital speech signal analysis.

POLQA covers a model to predict speech quality by means of digital speech signal analysis.

Speech enhancement aims to improve speech quality by using various algorithms.