![]() Managing gain also provides reasonable headroom for the AEC input signal. ![]() Ensuring there is suitable gain for the input signal will keep the signal-to-noise ratio (and thus the ERL level) as low as possible. The best way to control the ERL is with a good gain structure setup. The faster the convergence rate, the faster the AEC processor can account for changes in the room, such as a person or microphone moving. The convergence rate measures how fast the AEC algorithm can recognize and remove echo from the signal path. The algorithm will continue to work with ERL readings higher than 10dB, but the convergence rate will decrease in that range. The higher the ERL, the harder it is to completely remove the echo.įor BSS audio devices, AEC works flawlessly with ERL meter readings below 10dB. An ERL meter measures the room’s natural attenuation of the audio as it leaves the loudspeaker and re-enters the microphone. ERL measures how loudly the secondary audio (that is, the “echo” from the loudspeakers) is coming into the near side microphone, and assesses how closely the AEC reference signal matches the AEC input signal from the microphone. There are several parameters in AEC, but the single most important one to consider is Echo Return Loss (or ERL). Following the above rule of thumb ensures this requirement is met.ĪEC Wiring in HARMAN Audio Architect Software In particular, care must be taken that any dynamic processing such as compression or limiting employed on the loudspeaker output signal is also applied to the reference signal. This keeps the AEC algorithm well informed of any audio processing that ultimately alters the sound of the loudspeakers. “Send to the reference whatever you’re sending to the loudspeaker.” The AEC algorithm is “told” about audio coming out of the loudspeaker through a special input called the “reference.” Sending the right signal to the reference is critical. It essentially works by “telling” the microphone to ignore any sounds coming out of the loudspeaker. The goal of AEC is to remove this echo in the signal. In addition, acoustic elements in the near-side room can introduce more echo into the sound picked up by the microphones, thus increasing the amount of echo in the output signal. ![]() Because of the inherent delays of transmitting audio from one geographical location to another, this transmitted signal is a delayed version of the original voice, thus sounding like an echo. This audio is picked up by microphones in the near-side room and then transmitted back to the far side. Without a firm grasp of how AEC functions, it’s hard to understand the various ways it can be applied.ĪEC is an audio processing effect found in Digital Signal Processors (DSPs) that are designed for audio conferencing, when there is a room with microphones and loudspeakers on the “near side” of a phone or online call as well as someone at the “far side.” The goal of AEC technology is to remove what’s referred to as “acoustic echo,” a byproduct of performing an audio call in a room with microphones and loudspeakers.Īcoustic echo occurs on a phone call when the far-side speech (from the distant person) is played over local loudspeakers in the near-side room. This is because there is a lot of abstract thinking involved, making it hard to explain what AEC actually does. It’s a standing joke within the AVL industry to refer to the work of AVL integrators as “the dark arts.” If that’s true, then Acoustic Echo Cancellation (or AEC) is a truly special kind of dark magic that the many use, but only the most talented of audio wizards truly understand.
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