(1) (Metal Oxide Semiconductor) See MOSFET.|
(2) (Mean Opinion Score) The quality of a digitized voice line. It is a subjective measurement that is derived entirely by people listening to the calls and scoring the results from 1 to 5. Toll quality audio is generally considered to have a MOS rating of 4 and above.
The MOS is an average of the numbers for a particular codec. Because MOS testing requires carefully prepared and controlled test conditions, the best way to get a MOS test done is to have it outsourced. See codec.
An Objective Model
The E-Model is another rating system that provides an objective measurement of quality based on packet loss, jitter and delay. The E-Model reports results as R-values. Following is an approximate relationship between MOS and E-Model quality ratings.
Subjective Interpretation MOS R-Value
Excellent - almost all satisfied 4.5 90
Very good - most users satisfied 4.0 80
Good - some users dissatisfied 3.6 70
Fair - many users dissatisfied 3.1 60
Poor - most users dissatisfied 2.6 50
Bad - not recommended 1.0 0