Chai Wutiwiwatchai

Work place: Human Language Technology Laboratory National Electronics and Computer Technology Center, Pathumthani, Thailand



Research Interests: Human-Computer Interaction, Natural Language Processing, Speech Recognition, Speech Synthesis


Chai Wutiwiwatchai: received B.Eng. (Electrical Engineering – 1st Honor) from Thammasat University and M.Eng. (Electrical Engineering – Excellent Thesis) from Chulalongkorn University, Thailand, in 1994 and 1998 respectively. Then he received Ph.D. (Computer Science) from Tokyo Institute of Technology, Japan, in 2004. He is currently the head of Human Language Technology Laboratory, NECTEC, Pathumthani, Thailand. He is expert in human-machine interaction, speech technology and natural language processing.

Author Articles
Speech Quality Assessment of VoIP: G.711 VS G.722 Based on Interview Tests with Thai Users

By Therdpong Daengsi Chai Wutiwiwatchai Apiruck Preechayasomboon Saowanit Sukparungsee

DOI:, Pub. Date: 8 Mar. 2012

This paper presents the comparison between two codecs, G.711 and G.722 at 64 kbps, referring to speech quality perception using a subjective method called interview tests. These subjective tests have been conducted with 201 subjects, who are Thai native speakers that use Thai which is a tonal language, for accuracy and reliability of results. The results from testing with both codecs are almost the same; the scores are 4.17 for G.722 and 4.14 for G.711. After analyzing the results, it has been confirmed that G.722 does not provide better speech quality than G.711 to the Thai subjects significantly, which is consistent with previous information. However, these results could be used as the benchmark of G.711 and G.722 for speech quality assessment within Thai environments.

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