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TLV320AIC3262: Digital microphone is exceptionally sensitive using AGC

Part Number: TLV320AIC3262

Hello everyone,

I'm developing a handheld device which uses a digital microphone into an TLV320AIC3262 to capture speech audio.

In the screenshot you can see the PurePath audio chain. I've added an AGC block and it's configuration is displayed in Properties.

The problem is that the digital microphone audio input is extremely sensitive. It's picking up the speech from people in neighbouring rooms!

I need the AGC to capture the users speech whether they hold the microphone right next to their mouth or at arms reach. But any speech or noise coming from a further distance should be suppressed.

Can anyone suggest which values I should adjust to achieve the above? Perhaps someone has a working set of values they can share?

Thanks in advance.

  • Hi, John,

    I would recommend you to take a look to this app note, where the AGC function is explained with more detail. Based on your comments, it is possible that you need to increase the noise level up to a point where the speech you are capturing is under it and hence, not amplified by the AGC.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer