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4.5.2.
AUTOMATIC ECHO CANCELLATION (AEC)
This process uses the stereo audio from the product as a reference signal to model the echo
characteristics between each loudspeaker and microphone, caused by the acoustic environment of
the device and room.
The AEC uses four models to continuously remove echoes in the microphone audio input created in
the room by the loudspeakers. The models continually adapt to the acoustic environment to
accommodate changes in the room created by events such as doors opening or closing and people
moving about. The figure below illustrates the echo paths in two sizes of room..
Figure 4-11 Echo paths from the speakers to the microphones
After reset, or when echo paths change due to a change in the environment, the AEC will re-converge.
Echo Return Loss Enhancement (ERLE) can be used to indicate the degree of convergence on the
AEC filters as shown below.
Figure 4-12 Settling time of the AEC shown using an ERLE plot
XM-014232-PC
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