Attributes that controls the behavior of the echo cancellation for on all B-Channels of the current interface. Simply put, echo is the phenomenon of hearing one's own voice, with a delay. The larger this delay, the more discomfort experienced by the individual hearing it. Beyond a certain threshold, conversation is impeded and becomes unnatural.Echo Cancellation devices provide a means to remove echo, as it is detrimental to communication. The ITU defines echo cancellation as follows: "Echo cancellers are voice operated devices placed in the 4-wire portion of a circuit (which may be an individual circuit path or a path carrying a multiplexed signal) and are used for reducing the echo by subtracting an estimated echo from the circuit echo." (ITU-T G.168)
When the echo cancellation is performed by the hardware, the echo cancellation is applied on the last 128ms of audio data without impacting the host CPU usage.