An Open source Implementation of ITU-T Recommendation P.808 with Validation

TL;DR

This paper presents an open-source implementation of ITU-T P.808 for crowdsourced speech quality assessment, validated against laboratory results, with enhancements for speed and reliability in the testing process.

Contribution

The authors developed and validated an open-source, scalable implementation of ITU-T P.808 that includes new test methods and operational improvements for crowdsourcing speech quality evaluations.

Findings

MOS scores closely match laboratory results

Reproducibility of crowdsourced assessments is high

System enhancements improve reliability and efficiency

Abstract

The ITU-T Recommendation P.808 provides a crowdsourcing approach for conducting a subjective assessment of speech quality using the Absolute Category Rating (ACR) method. We provide an open-source implementation of the ITU-T Rec. P.808 that runs on the Amazon Mechanical Turk platform. We extended our implementation to include Degradation Category Ratings (DCR) and Comparison Category Ratings (CCR) test methods. We also significantly speed up the test process by integrating the participant qualification step into the main rating task compared to a two-stage qualification and rating solution. We provide program scripts for creating and executing the subjective test, and data cleansing and analyzing the answers to avoid operational errors. To validate the implementation, we compare the Mean Opinion Scores (MOS) collected through our implementation with MOS values from a standard laboratory experiment conducted based on the ITU-T Rec. P.800. We also evaluate the reproducibility of the result of the subjective speech quality assessment through crowdsourcing using our implementation. Finally, we quantify the impact of parts of the system designed to improve the reliability: environmental tests, gold and trapping questions, rating patterns, and a headset usage test.