3.7 AEC optimized design

Communication products are usually equipped with microphones and speakers. When making a call, the microphone will receive the sound signal by the speaker and enter the system through the microphone again, it will cause the system to generate echoes that interfere with the call. To eliminate the system whistling sound, it is generally necessary to cooperate with the DSP to effectively eliminate it. The microphone can adopt a uni-microphone to reduce the signal from the rear speaker. The microphone must be as far away from the speaker as possible, and the two should not be installed on the same plane. (Fig.7.1)

Fig.7.1 Speaker Phone Acoustic Echo Issue

However, the combination of the speaker and the mechanism should be designed to prevent the vibration of the speaker transmitted to the microphone, which will make the echo and distortion more serious. Finally, the DSP and AEC algorithm are used to calculate to eliminate the echo, so the echo can be attenuated to the minimum and improve the call quality (Fig.7.2).

Fig.7.2 AEC (Acoustic Echo Cancellation)