Performance analysis of perceptual speech quality and modules design for management over IF network

Voice packets with guaranteed QoS (Quality of Service) on the VoIP system are responsible for digitizing, encoding, decoding, and playing out the speech signal. The important point is based on the factor that different parts of speech over IP networks have different perceptual importance and each part of speech does not contribute equally to the overall voice quality. In this paper, we propose new additive noise reduction algorithms to improve voice over IP networks and present performance evaluation of perceptual speech signal through IP networks in the additive noise environment during realtime phone-call service. The proposed noise reduction algorithm is applied to preprocessing method before speech coding and to post-processing method after speech decoding based on single microphone VoIP system. For noise reduction, this paper proposes a Wiener filter optimized to the estimated SNR of noisy speech for speech enhancement. Various noisy conditions including white Gaussian, office, babble, and car noises are considered with G.711 codec. Also, we provide critical message report procedures and management schemes to guarantee QoS over IP networks. Finally, as following the experimental results, the proposed algorithm and method has been prove for improving speech quality.