DAENGSI, T., WUTIWIWATCHAI, C., PREECHAYASOMBOON, A., & SUKPARUNGSEE, S. (2013). IP Telephony: Comparison of Subjective Assessment Methods for Voice Quality Evaluation. Walailak Journal of Science and Technology (WJST), 11(2), 87–92. Retrieved from https://wjst.wu.ac.th/index.php/wjst/article/view/577