Echo suppression and cancellation
![An adaptive echo canceler for a telephone circuit. The function of H, the hybrid transformer, is to route incoming speech from the far end xk to the local telephone and route speech from the telephone to the far end. However, the hybrid is never perfect, so its output dk contains both the desired speech from the local telephone plus filtered speech from the far end. The echo canceller is the adaptive filter fk, which attempts to minimize the error signal εk by filtering the incoming far end speech into a replica yk of the far end speech that leaks through the hybrid. Once the adaption is complete, the error signal consists mostly of speech from the local telephone.](/Images/godic/202501/10/Telephone_Echo_Canceller1404.png")
Echo suppression and echo cancellation are methods in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective quality, this process increases the capacity achieved through silence suppression by preventing echo from traveling across a network.