Intelligibility evaluation of speech coding standards in severe background noise and packet loss conditions

Speech intelligibility is an important aspect of speech transmission but often only the quality is evaluated using perceptual tests when speech coding standards are compared. In this study, the performance of three wideband speech coding standards, adaptive multi-rate wideband (AMR-WB), G.718, and enhanced voice services (EVS), is evaluated in a subjective intelligibility test. The test covers different packet loss conditions as well as a near-end background noise condition. Additionally, an objective quality evaluation in different packet loss conditions is conducted. All of the test conditions extend beyond the specification range to evaluate the attainable performance of the codecs in extreme conditions. The results of the subjective tests show that both EVS and G.718 are better in terms of intelligibility than AMR-WB. EVS attains the same performance as G.718 with lower algorithmic delay.