VOICE DYNAMIC RANGE COMPRESSER OF ECHO RESIDUAL LINKING TYPE

摘要

PROBLEM TO BE SOLVED: To prevent generation of any inconvenience even when the coefficient estimation of AEC has not completed yet by allowing a inputted reception signal to pass through a specific filter and then sending it to an adaptive filter as a reference signal so as to narrow a dynamic range to be on a fixed level. SOLUTION: An echo erasing quantity detecting part 6 detects an echo erasing quantity by fetching the detecting signal of a detecting point 9 and that of a detecting point 10 by a simultaneous frame with the portion of N samples as one frame. The part 6 always monitors the echo erasing quantity of an AEC 4 and along with the completion of the estimation of a filter coefficient at the AEC 4, the characteristics of a nonlinear filter 5 is shifted to operation for compressing the dynamic range to the utmost in a possible range. With the reduction of the echo residual depending on the progressing condition of the coefficient estimation of the AEC 4 from detected information by the part 6, the compressing characteristics of the nonlinear filter 5 is controlled to be OFF→MIN→MID→MAX.