1. A computer-implemented method to evaluate audio quality of a real-time communication system that includes at least two communication devices, comprising: receiving a reference script, the reference script containing linguistic contents in text form of an audio signal sent to at least one of the communication devices, wherein the reference script excludes audio; receiving the audio signal; generating an evaluation transcript in text form by applying speech recognition to the audio signal; comparing the reference script with the evaluation transcript; generating a call quality metric of the real-time communication system based on the comparison; determining a duration of a speaking turn; determining a duration of a listening turn from the audio signal being received by one of the communication devices; and estimating a communication delay of the audio signal based on the duration of the speaking turn and the listening turn.
2. The computer-implemented method of claim 1 , said determining a duration of the speaking turn including inputting a duration value.