Voice Quality Assessment in VoIP networks
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From: sevana on 25 May 2010 04:12 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 |