Speech scrambling prior to LPC coding

Source coding and encryption are linked theoretically by the aim of removing redundancy. However, so far, no attempt has been made to combine source coding and encryption together, except in lossless compression models. When applied to speech coding, this appears to be a novel idea for research which provides the potential for developing new designs and implementations. The authors have considered the effect of combined encoding and encryption on analysis-by-synthesis (AbS) LPC based techniques, a class of time domain speech compression algorithms which are widely used nowadays in commercial as well as military communication applications. A novel pre-processing speech scrambling algorithm (PSSA) is proposed, which given speech, produces a scrambled signal with speech like characteristics. The resulting signal can be then compressed by a low bit rate speech codec