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Thread: Question from a noob about audio input

  1. #1
    Junior Member
    Join Date
    May 2018

    Question from a noob about audio input

    Hello all,
    I just received the tutorial breadboard kit and began playing with it. The project that I'm trying to accomplish is:

    A. "listen" for a certain frequency tone with the onboard microphone in a room with moderate ambient noise.
    B. filter the audio input to exclude all of the noise pollution
    B. output the captured frequency to the monitor and light a series of LED's (onboard would be fine) when the prescribed frequency is found.

    That's it...

    The problem is that I went through the tutorials and can't seem to get it together.

    Thanks for any input or suggestions

  2. #2
    Junior Member
    Join Date
    May 2018
    Well, this is what I have come up with after scouring tutorials and examples from the web. There are a bunch of unused variables declared for future use, and this code is obviously a mess that I'll clean up once I know that I'm on the right track. I can't tell whether I'm actually getting input to the onboard Mic and get no output to the serial monitor.

    My question is; would it be better to go the FFT or NoteFrequency route?

    #include <SerialFlash.h>
    #include <Audio.h>
    #include <Wire.h>
    #include <SPI.h>
    const int LedPin = 13; // LED Pin- for Teensy 3.2 with soundshield = Pin 13
    const int ThresholdBin = 51; // FFT1024 bin for 2200 Hz at 44100 input
    const int ListenFrequency = 2200; // Threshold frequency if FFT is not used
    const int BeepCnt = 3; // Number of tones in signal pattern
    /*NoteFrequency Code part 1 */
    AudioInputI2S             i2s1;
    AudioAnalyzeNoteFrequency notefreq;
    AudioOutputAnalog         i2s2;
    AudioMixer4               mixer;
    AudioConnection patchCord0(i2s1, 0, mixer, 0);
    AudioConnection patchCord1(mixer, 0, notefreq, 0);
    AudioConnection patchCord2(mixer, 0, i2s2, 0);
    AudioControlSGTL5000     sgtl5000_1;
    /* End NoteFrequency Code Part 1 */
    void setup() {
      pinMode (LedPin, OUTPUT); //Set LED to output mode
      digitalWrite (LedPin, LOW); // set onboard LED to OFF
    /* Initialize the soundshield onboard microphone */
    void loop() {
       // read back fundamental frequency
        if (notefreq.available()) {
            float note =;
            float prob = notefreq.probability();
            Serial.printf("Note: %3.2f | Probability: %.2f\n", note, prob);
    Thanks for any input

  3. #3
    Junior Member
    Join Date
    May 2018
    I was waaaay over thinking this. I found a better solution.

    Thanks all

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