Hi, I am using STM32H750-DK kit. Using the BSP example. I want to reduce the background noise of the microphone of the kit. Could you please help me in that please?

[SDand.11]

I need to pass lower frequencies only from the microphone (20Hz to 150Hz). How to add band pass filter?

[AWang.8]

Are you well versed with digital filter theory or experienced with implementing them?

There are a few options, direct implementation of FIR or IIR filters, or convolution of the filter's impulse response in time or frequency domain. The processor has hardware acceleration for both direct time domain filters(please confirm/correct), and frequency domain convolution using FFT acceleration.

Also in the BSP example, the microphone is already high pass filtered at below 20Hz to remove DC offsets. It is also low pass filtered for the PCM conversion process, but I think you could probably adjust it to fit your need if you don't want to learn about digital filters.

[SBEN .2]

Hello @SDand.1​ ,

This video could help you: CMSIS DSP Library FIR Low Pass Filter example.

Otherwise, in case you need "general" noise reduction, there are many noise cancelling algorithms that you can use. Traditionally, adaptive filtering (Kalman filter for example) are used with acceptable noise rejection.

Best regards,

@SBEN .2​