Understanding MOS

Voice quality is typically expressed in terms of the mean opinion score (MOS), which from its origins is a subjective rating of audio quality on a scale from 1 to 5. For many relevant use cases, such as customer experience management and SLA monitoring, it is not practical to ask test persons for their opinion. The original concept has therefore been extended to cover cases where MOS is not the result of an empirical study but the output of a computer-based analysis.

Today, there are many standards and recommendations describing algorithms for estimating different kinds of MOS. This includes objective MOS measurements obtained from active measurements (MOSLQO, MOSCQO) and estimated MOS values (MOSLQE, MOSCQE) from passive methods. In addition, MOS can be provided on different scales, depending on whether users can expect wideband high-quality audio or standard ISDN quality.

Voipfuture timeslicing technology calculates a MOS for each 5 second RTP segment offering a highly detailed assessment of the user experience.