Difference Between R-Factor and MOS Score

R-factor and MOS (Mean Opinion Score) are two commonly used metrics to evaluate the quality of speech codecs, which are algorithms that compress audio signals for transmission or storage. The R-factor is a common measure of speech quality in the telecommunications sector. MOS is a subjective measure of speech quality obtained by asking human listeners how well a speech signal is received.

Read this article to find out more about R-Factor and MOS Score and how they are different from each other.

What is R-Factor?

In the telecommunications industry, the R-factor is a widely used objective measure of speech quality. It is used to evaluate voice communication quality in a number of applications, such as VoIP (Voice over Internet Protocol), video conferencing, and wireless networks.

The R-factor is based on ITU-T G.107, which specifies a model for estimating the subjective quality of speech transmission in IP networks. The model accounts for several flaws that can degrade the quality of speech transmission, such as packet loss, delay, and jitter.

The R-factor is calculated using a number of technical parameters that affect the quality of the voice stream. Signal-to-noise ratio (SNR), delay, jitter, and packet loss are examples of these metrics. Each of these parameters is assigned a weight based on its significance in determining voice quality.

The R-factor is widely used in the telecommunications industry, and ITU-T (International Telecommunication Union, Telecommunication Standardization Sector) standardized it in Recommendation G.107. It is a useful tool for evaluating voice communication quality and troubleshooting problems in real-time communication systems.

What is MOS Score?

MOS is a subjective measure of speech quality that is commonly used in the audio industry to evaluate the quality of speech codecs and other audio processing algorithms. The MOS score is obtained by asking human listeners about the quality of a voice signal. Listeners are typically asked to rate the quality on a scale of 1 to 5, with 1 being the worst and 5 being the greatest. MOS scores are obtained by averaging the ratings of several listeners

The MOS exam is a standardized test conducted in a controlled environment with high-quality audio equipment. Listeners are presented with a series of speech samples that have been processed using the codec or algorithm being evaluated during the test. On a scale of 1 to 5, listeners are asked to rate the quality of each sample. The MOS score is calculated by averaging the ratings.

MOS scores are a measure of the quality of speech transmission that takes human perception into consideration. Background noise, echo, delay, and distortion all have an effect on MOS scores. MOS scores can be used to compare the quality of various codecs or algorithms as well as evaluate the impact of various factors on speech quality.

MOS scores are often used in conjunction with objective measurements of voice transmission quality, such as the R-factor. Objective measures evaluate the technical quality of the gearbox, whereas MOS ratings assess the perceived quality of the gearbox. It is feasible to gain a more complete picture of the quality of speech transmission by integrating objective and subjective criteria.

In the audio industry, MOS ratings are often used to evaluate the quality of speech codecs, voice assistants, and other speech processing algorithms. MOS scores can be used to guide the development of new algorithms as well as identify problems with speech quality. MOS scores are also used to compare the performance of different codecs and algorithms, as well as to benchmark system performance.

Difference between R-Factor and MOS Score

The following table highlights the major differences between R-Factor and MOS Score −



MOS Score

Type of measure




0 to 100

1 to 5


Telecommunication industry

Audio industry


Higher values indicate better quality.

Higher values indicate better quality.

Method of measurement

computed from technical parameters

obtained from human perception


Provides an objective measure of technical quality.

Takes into account human perceptions of quality


Quality of Service (QoS) monitoring and network troubleshooting

Algorithm development, codec evaluation, and system benchmarking


In conclusion, the R-factor and MOS score are two different metrics used to evaluate the quality of speech codecs. The R-factor is an objective measure that takes into account technical aspects including signal-to-noise ratio, latency, and packet loss, whereas the MOS score is a subjective measure based on human perception.

In the telecommunications business, the R-factor is typically used, whereas the MOS score is used in the audio industry. Both metrics are useful in evaluating speech codecs, and their interpretation should take context into account. Finally, the metric selected will be based on the specific application and evaluation goals.

Updated on: 15-May-2023


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