![highest performance acoustic echo cancellation highest performance acoustic echo cancellation](https://www.ceva-dsp.com/wp-content/uploads/2017/12/04_05_21_NLSP_Block_Diagram_v5.1_corrections-002-1024x735.png)
It is the most demanding state for the AEC algorithm. Double talk This occurs when speech is generated on both ends of the line. Residual echo Residual acoustic echo signal that was not removed by the AEC algorithm. Loss of convergence is most commonly caused by incorrect gain structure. Loss of convergence occurs when the AEC algorithm cannot track acoustic echo path changes resulting in echo being heard by the far end. An algorithm 'converges' when it efficiently modifies the parameters of the adaptive filter and echo is removed. The convergence rate indicates how quickly the AEC algorithm models the room and adapts to echo path changes. Convergence rate / Loss of convergence Convergence refers to the adaptation process inside the AEC algorithm. The tail length of Biamp's AEC technology is up to 300ms. Understanding the inherent issues and common problems faced with these installations is an important step for every designer/installer.Ĭommon AEC terms Tail length Tail length refers to the maximum echo time delay that will be removed by the AEC algorithm. However we recognize the aestheic bias toward micing from above and will work to help get the best results possible with all configurations.
![highest performance acoustic echo cancellation highest performance acoustic echo cancellation](https://149351962.v2.pressablecdn.com/wp-content/uploads/2015/06/aec_sst_two_rooms_showing_echo_v2-1024x332.png)
Poor Signal-to-Noise Ratio (SNR) due to low voice volume relative to ambient room noise - due to distance from the mic.įor all these reasons, and from our years of experience with AEC systems, Biamp Systems does not recommend using ceiling microphones if it is practical to use individual mics for participants.Poor voice pickup due to low voice volume relative to ambient room noise - due to distance from the mic.Poor gain before feedback due to low voice volume relative to ambient room noise - due to distance from the mic.Poor voice pickup due to the distance from and off-axis position relative to the participant's mouths.ERL values will very likely be positive since acoustic echo loss between the loudspeaker and microphone is minimal - the mics are very close to the speakers.They present the worst conditions for acoustic coupling between the microphone and the speaker, as both may be physically mounted in the same surface.
![highest performance acoustic echo cancellation highest performance acoustic echo cancellation](https://ars.els-cdn.com/content/image/3-s2.0-B9780128129760000051-gr004.gif)
While commonly used, ceiling mics are problematic for the following reasons: Microphone gain is too low or the AEC Reference signal is too highĪverage or possibly poor performance results Increase signal fed to AEC reference to artificially lower the ERLĪcoustic echo loss between the loudspeaker and the microphoneĮxtreme Negative Values: ERL between -30dB and -16dB Problematic microphone/ speaker placementįar end signal to the AEC reference is too lowĪEC algorithm may not be able to converge properly Not enough signal being fed to the AEC reference.Input gain of the microphone is too high.There is probably too much acoustic coupling between the microphone and the speaker as explained in the AEC basics section. Once operational, make level changes as required but do not change the volume of the amplifier.If the value is positive, it indicates that amplifier volumes are too high or microphones are too close to the speaker. For best performance results, ERL value shall be between 0 and –16dBu while the far end talks. Check the Echo Return Loss (ERL) Value in the Advanced parameters on each AEC input.Do a test call and then adjust microphone levels if required.Then slowly bring up the levels of your amplifiers until you have sufficient signal.
![highest performance acoustic echo cancellation highest performance acoustic echo cancellation](https://www.prosoundweb.com/wp-content/uploads/2020/07/image-9-768x208.png)