ON THE APPLICATION OF RLS ADAPTIVE FILTERING FOR VOICE PITCH MODIFICATION
Luiz W. P. Biscainho, Sergio Lima Netto · 2007
This paper presents a pitch modification scheme, based on the recursive least-squares (RLS) adaptive algorithm, for spe ech and singing voice signals. The RLS filter is used to determine the linear prediction (LP) model on a sample-by-sample framework, as opposed to the LP-coding (LPC) method, which operates on a block basis. Therefore, an RLS-based approach is able to preserve the natural subtle variations on the vocal tract model, avoidin g discontinuities in the synthesized signal and the inherent fra me-delay associated to classic methods. The LP residual is modified in the synthesis stage in order to generate the output signal. List ening tests verify the overall quality of the synthesized signal u sing the RLS approach, indicating that this technique is suitable fo r realtime applications.