CA2167552A1 - Speech Encoder with Features Extracted from Current and Previous Frames - Google Patents

Abstract

In a speech signal encoder device comprising a frame divider (31) for producing original speech frames, a mode decision circuit (49) decides a predetermined number of modes by using feature quantities which are extracted from each current speech frame segmented from an input speech signal at a predetermined frame period of as short as 5 ms and from a previous speech frame segmented at least one frame period prior to the current speech frame. Preferably, a weighing circuit (47) provides the current speech frame by perceptually weighting the original speech frames into weighed speech frames. It is possible to provide the feature quantities by a primary quantity and as a secondary quantity by a rate of variation in the primary quantity. Each feature quantity is preferably adjusted into an adjusted quantity in response to each current mode decided by using the current speech frame and a previous mode decided at least one frame period prior to the current mode. Each feature quantity may be a pitch prediction gain, a short-period predicted gain, a level, or a pitch of each original speech frame.