Mean Opinion Score


Mean Opinion Score (MOS) is a standardized measurement used to evaluate and quantify the subjective quality of audio or video communication services. It involves gathering feedback from a panel of human evaluators, who rate the quality of samples on a scale of 1 (lowest) to 5 (highest). The results are then averaged to determine the overall MOS, providing valuable information on the perceived end-user experience.

Key Takeaways

  1. Mean Opinion Score (MOS) is a standardized subjective measurement technique used to assess the overall perceived quality of various services, such as telecommunications, audio, and video.
  2. It uses a rating scale that ranges from 1 (poor) to 5 (excellent) and relies on human evaluators to provide their opinions on the quality of the assessed service, resulting in an averaged numerical score.
  3. MOS is widely utilized in the industry to evaluate and optimize communication systems and codecs, ensuring customer satisfaction and system performance improvements.


The Mean Opinion Score (MOS) is a significant technology term, as it serves as a valuable tool for assessing and quantifying the perceived quality of various forms of communication, such as audio, video, and data transmissions in telecommunication networks.

By measuring user satisfaction, it provides critical insights to service providers, enabling them to identify potential issues, optimize the performance of their systems, and enhance the overall user experience.

As technology continues to evolve, the MOS remains an increasingly relevant metric for understanding end-user perceptual experiences and driving continuous improvement in communication services.


Mean Opinion Score (MOS) serves a vital purpose in the assessment of the quality of audio and video systems, particularly in telecommunications. Its primary function is to gauge the overall satisfaction of users with the experience provided by these systems.

For both service providers and equipment manufacturers, MOS is an indispensable quantitative tool to assess subjective user perceptions, which can significantly impact the perceived value of their products and services. To ensure customer satisfaction, it is crucial to maintain the quality of service, and MOS measurements help in identifying the areas that may need improvements or modifications, such as voice and video quality, network performance, and user interfaces.

This subjective measurement technique essentially involves human listeners or viewers to evaluate a specific sample of audio or video clips on a scale of one to five, with higher scores indicating a more satisfactory experience. Participants are asked to provide their opinions on various parameters like audio clarity, distortion, latency, and any other potential issues that could affect their overall experience.

These individual scores are then averaged to determine the service or equipment’s Mean Opinion Score. With its ability to provide valuable insights into user preferences and overall satisfaction, MOS continues to be an essential metric used across industries to identify and resolve performance issues, enhancing end-user experiences.

Examples of Mean Opinion Score

Mean Opinion Score (MOS) is a numerical rating system typically used to assess the quality of voice, audio, and video transmission systems. It provides a score on a scale of 1 to 5, with 1 being the lowest quality and 5 being the highest quality. Here are three real-world examples of MOS being used:

VoIP (Voice over Internet Protocol) Quality Assessment: MOS is frequently used to evaluate the voice quality of VoIP systems, such as Skype, WhatsApp, and Zoom. It does this by measuring different factors such as latency, jitter, and packet loss. MOS provides a quantitative score that can be used to monitor and improve the quality of voice communication, ensuring user satisfaction.

Video Streaming Quality Evaluation: In video streaming services like Netflix, Hulu, and YouTube, MOS is utilized to assess the quality of video transmissions. These services rely on stable and high-quality video streams to keep customers happy, so understanding the MOS helps developers optimize encoding algorithms, compressions, and streaming techniques to provide the best possible audio and video experience for viewers.

Telecommunication Network Efficiency: Telecommunication companies like AT&T, Verizon, and T-Mobile use MOS to evaluate the performance of their networks. By analyzing call quality and other aspects of voice and data transmissions, these companies can identify areas of improvement and allocate resources accordingly, optimizing their networks to provide better call experiences for their customers.

Mean Opinion Score (MOS) FAQ

1. What is Mean Opinion Score (MOS)?

The Mean Opinion Score (MOS) is a numerical representation of the quality of a communication medium, typically applied to telephony services or an audio codec. It measures the quality of an audio or video experience on a scale of 1 to 5, with 1 representing poor quality and 5 representing excellent quality.

2. How is MOS calculated?

MOS is calculated by taking the average of a group of subjective test scores given by human listeners, who rate the quality of an audio or video experience during a test. Each listener assigns a score from 1 to 5, and the average of these scores is the final MOS value.

3. What factors affect the MOS rating?

Several factors can affect the MOS rating, including the audio codec used, network conditions, transmission method, background noise, the listener’s perception, and experience. The goal is to optimize these factors to achieve the highest possible MOS rating, which indicates good voice or video quality.

4. What is the difference between subjective and objective MOS?

Subjective MOS is derived from actual human listeners’ ratings, while objective MOS is an estimated value obtained using algorithms that mimic human perception. Objective MOS provides a faster and more consistent way of assessing quality, although it may not perfectly match subjective MOS in all cases.

5. How is MOS used in telecommunications?

In telecommunications, MOS is used to evaluate and optimize voice and video transmission systems. Network operators use MOS to monitor audio quality and diagnose any degradation in performance. Designers use MOS to compare different audio codecs and find the best balance between audio quality and bandwidth requirements.

Related Technology Terms

  • Quality of Experience (QoE)
  • Perceptual Evaluation of Speech Quality (PESQ)
  • Subjective Listening Test
  • ITU-T Recommendation P.800
  • (singleended) R value

Sources for More Information


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