Improving pitch estimation for efficient multiband excitation coding of speech

The authors describe an improved pitch detection algorithm for efficient multiband excitation (MBE) coding of speech. The improved algorithm adds a corrective measure to the error measure for spectrum matching employed in conventional MBE pitch analysis. This corrective measure effectively applies equal weighting to all harmonic bands by normalising the error energy in each band. The result is the reduction of gross pitch errors owing to pitch doublings. An additional advantage of using this corrective measure is that, because this measure is based on a sum-of-product formula, comparisons of matching scores may be performed with partial-sums computed during the evaluation of the measure, therefore, facilitating fast searching of the optimum pitch period. Simulation results show that, with the deployment of the improved algorithm, pitch tracking procedure is no longer needed, and the coding delay of the MBE coder is significantly reduced.