From: sevana on
There are two main methods to assess voice quality subjective and
objective. Subjective method involves human listeners to evaluate voice
quality thus being able to discover all relevant sides of voice quality.
ITU has developed a set of recommendations for subjective testing including
P.800 that defines an important metric – Mean Opinion Score (MOS) that is
used by the testers to determine the audio (in particular speech) quality
grade: 5 – Excellent, 4 – Good, 3 – Fair, 2- Poor, 1 – Bad. Another
ITU-T recommendation was developed for subjective evaluation of speech
quality in communication systems – P.835. However, for obvious reasons
subjective tests are not quite suitable for real communication systems
especially when QoS monitoring is involved.

In order to automate the evaluation Perceptual Evaluation Speech Quality
method was introduced in ITU-T recommendation P.861 and P.862. However,
this approach employs a reference speech signal to be transmitted over a
telecommunication channel and that is not convenient for single-end
measurements. This issue was solved by introducing non-intrusive voice
quality testing methods described in P.563.

There are certain limitations in both approaches especially when talking
about VoIP assessment. For further information on PESQ limitations for
measuring voice quality in VoIP and mobile networks we would like to refer
to this white paper: Limitations of PESQ for Measuring Voice Quality in
Mobile and VoIP Networks.

Sevana company has developed two successful alternatives for both intrusive
and non-intrusive methods that have already found their way to the
customers who appreciate our technology in their communication systems.
Further more, we have developed a solution specifically devoted to VoIP
intrusive and non-intrusive testing.

There are the following main ways our customers utilize AQuA (Audio Quality
Analyzer):

Read more at:
http://www.sevana.fi/voice-quality-assessment-in-voip-networks.php