We are proposing an error protection and packet loss concealment system, based on a modified sinusoidal vocoder. By a few additional phase parameters, the vocoder is able to partially track the original signal during voiced segments. This signal tracking allows us to seamlessly switch between the vocoded signal and a primary encoded signal. A packetized speech transmission system, using PCM data as primary encoding, and the modified vocoder as a sub-coder, is simulated and evaluated using

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... tive preference testing. Packet loss concealment based on extrapolation of the vocoder parameters is found to perform well, especially at high error rates.