A new system for reliable pitch extraction of speech

The causes of errors in conventional pitch extraction methods can be classified into two categories: 1) extrinsic factors that come from the analysis methods, such as imperfect signal representation due to inappropriate shape, width, and placement of the analysis window, etc., and 2) intrinsic factors that reside in the speech signal itself, such as the occurrence of a strong harmonic component or a sub-harmonic component, etc. In fact, fixed frame size and frame shift, adopted in most of the conventional systems, are responsible for a considerable part of their gross pitch errors. In this paper we combine the use of running waveform analysis, an exponential analysis window, and a variable frame shift to cope with errors of the first category. Various new methods are also introduced to cope with causes of errors of the second category. The validity of the proposed methods is confirmed by experiments using speech materials from both male and female speakers.