"The ZL38001 device contains an acoustic echo canceller and a line echo canceller as well as the many control functions necessary to operate them. The ZL38001 provides clear signal transmission in both audio path directions to ensure reliable voice communication, even with low level signals. The ZL38001 provides high performance full-duplex operation similar to network echo cancellers so that users experience clear speech and uninterrupted background signals during the conversation. This prevents subjective sound quality problems associated with ""noise gating"" or ""noise contrasting"" associated to speakerphone echo cancellers using variable attenuators. The ZL38001 uses an advanced adaptive filter algorithm that is double-talk stable, which means that convergence takes place even while both parties are talking. This algorithm allows continual tracking of changes in the echo path, regardless of double-talk or variable echo condition of the environment. The echo tail cancellation capability of the acoustic echo canceller has been sized appropriately (112 ms) to cancel echo in an average sized office with a reverberation time of less than 112 ms."