Method and apparatus for rate reduction of coded voice traffic

A conversion entity and method for converting higher-rate speech parameters into lower-rate parameters including dimmed excitation parameters. The conversion entity comprises a first decoder configured to produce a target excitation from the higher-rate parameters, based on a first fixed contribution and a first adaptive contribution. The conversion entity also comprises a second decoder configured to produce a second adaptive contribution, and configured to selectably operate in a first or a second mode. In the first mode, the second adaptive component is generated based on the first fixed contribution for a previous frame, while in the second mode, the second adaptive component is generated based on a second fixed contribution for the previous frame. The second decoder operates in the second mode in response to a rate reduction request. A processing module determines the dimmed excitation parameters for generation of the second fixed contribution for the current frame, based on the target excitation and the second adaptive contribution.