A 4800 bps LPC vocoder with improved excitation
C.K. Un, Won Sung · 2005
We present an improved 4800 bps LPC vocoder system that virtually eliminates the buzzy effect from synthetic speech. Excitation signal in the new system is formed by adding high-pass filtered pitch pulses or random noise to a baseband residual signal (0 - 600 Hz) that has been coded by pitch predictive PCM. Since the baseband residual is used as a part of excitation, the system is also robust to V/UV and pitch errors. According to our informal listening tests, the synthetic speech of the new system does not have the buzzy effect. As a result the vocoder speech quality is more natural than that of a conventional LPC vocoder.