Mean Opinion Score

What Does Mean Opinion Score Mean?

Mean opinion score (MOS) is a common measurement of voice data quality used in Internet telephony. It uses the arithmetic mean of all individual scores to present an average result.


Techopedia Explains Mean Opinion Score

In compiling a MOS, listeners provide feedback on voice communications in segments. Using a rating system, they analyze the result of voice presentations according to the quality of the sound and to the consistency of the result.

The use of the word “opinion” indicates that this method is a somewhat subjective method of analysis. Rather than being based on arithmetic or statistical results, the MOS is based on the subjective feedback of human listeners. As a result, it may not be as reliable as quantitative analysis (e.g., analysis of data packets) for improving telecommunications projects.


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Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.