Is it possible to have only certain frequencies come in among the sounds coming into the microphone?

Projects General Guidance
1

I would like to allow only certain frequencies to come in and remove the rest.

I don't know how to configure the hardware and do the firmware

can someone help?

thank you

2

This is a very difficult task. It requires expertise and experience. What is your level of expertise and experience? What model of microphone and model of arduino do you want to use?

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3

Are you wanting to filter the sounds waves before the microphone or the electrical signals after? The former is possible but hard. The second needs an electrical filter after the mic, which could be either analogue, or digital implemented in the processor. What is the application and what range of frequencies do you want to pass? Depending on these we could give better advice. As Paul says, this is not an easy task!

4

This is what filters do.

You can either do them in the analogue hardware (ie, electronics), or in software = Digital Signal Processing (DSP).

What hardware, exactly, do you have?

Please post links to datasheets, specifications, etc; also your schematic for connecting things together.

EDIT:

As @jhaine suggested, you could also do it acoustically before the microphone.

Another option would be to use a "microphone" (or other sensor) that is tuned to only the frequency/ies of interest.

5

What frequencies do you want to allow?

6

Give us an idea of what you're trying to accomplish. For example, if you want to make a lighting effect that responds only to the bass, that can be done pretty easily.

And just in case you don't know this, all real world sounds contain many frequencies. For example, if two or more people are singing and talking at once, you can't remove one of the voices.

For analog filtering see the famous Active Filter Cookbook

DSP (Digital Signal Processing) may require something more powerful than a "basic" Arduino. DSP is "advanced processing" but there are libraries so you don't have to write all of the code yourself. There is a free online DSP book (not specifically for the Arduino).

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7

See if FFT solutions help your project.

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8

Band Pass Filter

9

If you want to get the amplitude of a handful of specific frequencies, such as to decode DTMF tones or FSK signals, the Goertzel algorithm might be useful.

10

As we're still waiting for @ahendml to explain what frequencies are of interest, it's impossible to say whether band pass, high cut, or low cut might be the most appropriate...

11

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