METHOD FOR PITCH SEARCHES BY SELECTING QUANTIZATION ERRORS

摘要

PURPOSE: A pitch searching method is provided to reduce searching time in a vocoder by indicating periodicity only about positive peaks while skipping decimated low-frequency components. CONSTITUTION: A zero state impulse response of an LPC filter is excluded from a voice signal negative frame(s(n)). The signal is passed through the LPC filter. The remaining signal has noise components and pitch components. The signal is decimated, and positive peak correlativity is inspected to obtain a relative pitch delay(ks). An absolute preliminary pitch range is obtained. A synthetic signal(yl(n)) is obtained by using a pitch delay. A sequential pitch searching is performed about a preliminary pitch range. Self-correlation and cross-correlation of E=Exy/Eyy are used to search pitches about the preliminary pitch range. The searched data is stored in a memory.