Control system of acoustic echo cancellers for telephone terminals with handset or handsfree

The invention proposes a variable step-size adaptation control method for acoustic echo cancellation digital filters for handset and hands-free telephone terminals. The variable step-size integrates a double-talk detector, an echo-path change detector and an automatic control of the background noise level. The invention is based on two supplementary adaptive filters with low memory length, which support the acoustic echo cancellation filter control. One supplementary filter monitors the near-end speech activity, while the other monitors the echo-path variations. Such control method provides several benefits: 1. A reliable adaptation control for a broad range of acoustic coupling levels between the loudspeaker/s and the microphone. 2. An adaptation control able to cope also with sudden and strong changes of the echo path. 3. An adaptation control with low computational complexity characterized by a reduced number of easily adjustable parameters. 4. An adaptation control that does not need any a-priori estimate of the acoustic coupling level between the loudspeaker/s and the microphone. 5. An adaptation control that can be applied to any gradient descendent adaptive algorithm