Effects of packet loss on 3 toll quality speech coders

The integration of voice and data switching using a packet based approach has been proposed in many forms. If speech coding is used in such a network, impairments such as lost packets affect the coder performance. The effect of packet loss on 3 toll quality speech coders is discussed. The coders are adaptive differential pulse coded modulation (ADPCM), subband coding (SBC) and adaptive predictive coding (APC). Their configurations adopted in the simulations are described. Damage resulting from loss of a speech packet is two-fold: firstly a missing speech segment is introduced for the lost duration; secondly the adaptation logic is disrupted after the lost segment. Therefore any compensation technique should aim to fill the missing segment as well as restoring the adaptation after the loss. The use of side-information was suggested in the case of SBC-APCM. The results showed successful compensation in the case of ADPCM, and SBC