Syntiant - Log Mel filterbank frequency band setting

In my current model: Emergency vehices alarm - Dashboard - Edge Impulse
I am trying to set features in the way, that model will evaluate ony certain frequency band .
I understood that this cold be done by setting 2 parameters of “Log Mel-filterbank energy features”: 1) Low frequency 2) High frequency
However the fields, where I am supposed to type a value are greyed out and initial value 0 can not be changed. Am I doing something wrong, or this can not be changed for Syntiant Audio parameters setting?
Is there other way, how to set the frequency band for ML model?


Instead of using the Audio Processing Block add 2 each Spectral Analysis Processing Blocks.

Make one Spectral Analysis Processing Block a high pass filter and the other a low pass filter so you create a notch filter.

I did not mentioned that I need to deploy the model into Syntiant TinyML board. My understanding is that Syntiant Audio processing block is the only one that is compatible with this HW. I am not sure if Spectral Analysis Processing Block can be used in this case.

I stand corrected.

You must use the Syntiant Processing Blocks. See this post. I assume when @jbuckEI refers to DSP blocks he is refering to what the EdgeImpulse Studio calls Processing Blocks.

Maybe jbuckEI can tell us why the fields are grayed out.

Do I understand correctly that you want the output of the Processing Block (yes @MMarcial that is what I meant) to output features only in the band of interest? If so, I can see how not being able to change the frequency settings is a limitation. I will have to look into why some values are fixed, though I suspect it has to do will how the NDP101 is designed.

There are a number of limitations for the NDP101, please read this example documentation carefully.

I’ll update more when I know, and get some more info into the docs.

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The Arduino Nicla Voice and the Syntiant TimyML boards both use a SoC that integrates a MEMs mic with a DSP that converts the signal to PDM. The PDM signal directly feeds the Syntiant AI Sensor (NDP101 or NDP120).

  • So there is no way to add a circuit to filter the analog signal.
  • It might be possible to put in a CPU between the Mic and Syntiant AI Sensor to create a filter on the PDM data.

Yes, that’s how I understood it. However, unless there is another way to implement the filter without any HW modifications, I will have to rely on the ML model, which hopefully will learn to omit unwanted low-frequency noise.