A new class of analysis by synthesis LPC coders: multipulse excited sunbed LPC

A new class of analysis by synthesis LPC algorithms, called multipulse excited subband (MESB), is presented. The proposed system differs from the conventional analysis by synthesis LPC systems in that the excitation sequence is defined by a sparse sequence of pulses in each subband. The pulses in each subband are determined by a closed loop optimization procedure similar to the multipulse excited linear predictive coding (MELPC). Since the excitation is split into different subbands, the sampling rate of the pulses in each subband is reduced to its corresponding Nyquist rate. The combinations of pulse positions in each subband are thus substantially diminished and hence the positional coding bit rates are reduced. Furthermore the system employs a closed-loop optimization procedure which evades aliasing distortion and interband leakage introduced by the imperfection of the filters