Pitch synchronous speech coding based on timbre vectors

Abstract

A pitch-synchronous method and system for speech coding using timbre vectors is disclosed. On the encoder side, speech signal is segmented into pitch-synchronous frames without overlap, then converted into a pitch-synchronous amplitude spectrum using FFT. Using Laguerre functions, the amplitude spectrum is transformed into a timbre vector. Using vector quantization, each timbre vector is converted to a timbre index based on a timbre codebook. The intensity and pitch are also converted into indices respectively using scalar quantization. Those indices are transmitted as encoded speech. On the decoder side, by looking up the same codebooks, pitch, intensity and the timbre vector are recovered. Using Laguerre functions, the amplitude spectrum is recovered. Using Kramers-Kronig relations, the phase spectrum is recovered. Using FFT, the elementary waves are regenerated, and superposed to become the speech signal.