The Voice Quality Objective Measurement System Considered Transmission Impairment

Since the21st century, with the rapid growth of network technology and multimedia services, people try to use the network to transfer multimedia data services. VoIP is based on the idea that voice conversations over the network. But the unreliability of non-real-time network makes the speech quality can’t be guaranteed. Therefore, it is necessary that effective perceived speech quality assessment models or methods for monitoring VoIP quality to ensure the service level. For this problem, this paper proposes a objective measurement model considered transmission impairments comprehensively, which provides overall score, as well as identifies the key factors causing decline in the quality of the transmission system to give users some guidance. This article follows specific work, which (2)-(5) as part of the main innovations.(1) Study voice quality evaluation methods and summarize the advantages, disadvantages and range of current measurement. Research VoIP system components and protocol structure and summarize the key factors affecting the quality of voice transmission.(2) Combined P.563and E-Model, this paper presents a evaluation model considered transmission damage comprehensively. The model maintain. around0.8subjective correlation results under various conditions.(3) According to the degree of impairment type of E-Model, this paper designs a standard mapping of make a quantization of different kind of impairment to MOS, so that the user can get the key factors causing speech quality degradation visually.(4) This paper proposes a listener echo parameter detection and estimation method based on signal correlation and added it to P.563 model. The correlation of the modified P.563model to the listener echo speech degraded database constructed by this paper increased to0.875from the original0.6101.(5) Echo parameter extraction algorithm is improved, which add double-talk state judging, delay effectiveness judging and echo intensity estimation based on the original detection algorithm, and execution speed has been optimized. Research and realize the network and delay parameters acquisition method, and verify the effect of extraction.(6) Build standard test speech database and degraded speech database, build a network simulation environment, and develop related software.