Speech coding using trajectory compression and multiple sensors

This paper presents a new method of multi-frame speech coding based upon polynomial approximation of speech feature trajectories incorporating multiple sensor signals from microphones, accelerometer, electro-glottograph, and microradar. The trajectory polynomial approximation exploits the inter-frame information redundancy encountered in natural speech. The trajectory method is applicable to features such as spectral parameters, gain, and pitch. The method is suitable for application to a frame vocoder to further reduce the transmission bit rate. Multiple transducers increase the intelligibility and quality of the coded speech in noisy environments. Experimental results are obtained by embedding the new method into an enhanced mixed-excitation linear prediction vocoder. The resulting vocoder operates at 1533 bps and preliminary intelligibility and quality tests show results comparable to those of the original 2400 bps vocoder.