"The ZL38002 device is comprised of an acoustic echo canceller and the necessary control functions for operation. The ZL38002 guarantees clear signal transmission in both transmit and receive audio path directions to ensure reliable voice communication, even when low level signals are provided. The ZL38002 does not use variable attenuators during double-talk or single-talk periods of speech, as do many other acoustic echo cancellers for speakerphones. Instead, the ZL38002 provides high performance full-duplex operation similar to network echo cancellers. This results in users experiencing clear speech and uninterrupted background signals during the conversation and prevents subjective sound quality problems associated with ""noise gating"" or ""noise contrasting"". The ZL38002 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, as long as a reference signal is available for the echo canceller."