Implementation of sub band coding and pitch extraction using cumulative impulse strength
K. Harisudha, Samiappan Dhanalakshmi, M. Madhusoodhanan · 2017
Pitch extraction is a challenging task in speech signal analysis because of its time varying characteristics of source. The impulses in a quasi-periodic sequence incorporated with noise are located by a temporal measure called as cumulative impulse strength. And it is subsequently used for detecting GCI using methods like Dynamic Programming Phase Slope algorithm (DYPSA) and Speech Event Detection using Residual Excitation and the Mean Based Signal (SEDREAMS). The technique of breaking down the source signal into constituent parts and decoding the parts separately is called Sub-band (SBC) coding. The speech signal is divided into two or more frequency bands and each of these sub band signal are coded individually in SBC coding. These sub-bands are processed and recombined to form the output signal, whose bandwidth covers the whole frequency spectrum. Decimation and interpolation in frequency domain are performed after decomposing the signal into low and high frequency components. Then the pitch extraction is implemented using cumulative impulse strength for DYPSA and SEDREAMS algorithms. The proposed structure significantly reduces error and preventive to additive noise and able to locate the Glottal Closure Instants (GCIs).