How should I align microphones for ANR algorithem on smart remote 3? can I set them back and front of remote (like mobile phones)?

[_Behn4m]

Hi everybody

I'm designing a new cutomremote based on smart remote v3, As I dont know much about the ANR algorithem of Nordic, so for mics I dont know how should place them. Should I align them on "right and left" or "top and botton"?

Thanks to all, Behnam

[Andreas]

Hi,

 

From a noise cancellation perspective, the microphones should be placed in each end of the PCB such that they both pick up approximately the same noise, and the noise reference mic does not pick up as much of the desired signal (and as much as possible of the noise) as the 'main' microphone. I suppose this corresponds to what you describe as 'top-bottom', having the 'main' microphone in the end which you typically speak into, and the noise reference microphone in the opposing end.

Having the noise reference microphone picking up more noise than speech might not be too easy to ensure, but it seems to be fine as long as the main microphone picks up speech that is higher than the noise microphone.

The algorithm should have some parameters to tune so that you can optimize the noise rejection for the specific design and distance between the microphones. You might still want to look at ways of testing different mounting positions.

 

Best regards,

Andreas

[_Behn4m]

Thank you Andreas for your response

So there is no other choice? I saw some other remotes such as Apple Siri remote that placed two mics one on top and other on back side . I think rhis alignment could be better (one receive user sound and other ambient noise),

And if it must align as in smart remote 3, does the distance of mics maters?

Regards

Behnam

[Andreas]

Hi,

 

I must apologize, I was under the impression that the algorithm was tuned for this algorithm. I edited my answer below, to hopefully not possibly confuse someone in the future.

 

It is true as you say, the noise reference mic should be placed closer to the noise source and further from the speech source, while the main speech microphone should be placed such that it captures the speech speech as well as possible. For some reason this is not done in the SR3 HW, but the algorithm should work fine with this top-bottom mic position. Precise distancing between the mics is not too important.

 

Again, sorry for the confusion.

 

Best regards,

Andreas

[_Behn4m]

Hi,

Thank you so much and now it is much more clear.

Best Regards

Behnam