Voice-activate with Micro:bit not working!

Juph · November 19, 2021, 9:18am

Hi All, I’m following Jan’s steps and able to build the project cloned from GitHub. This code works but when I tried to collect my own audio keyword dataset (5 minutes), create the model and then rebuild the whole project, it doesn’t work, the keyword (microbit) is not recognized, in the best case I get around 0.4 of confidence ! Someone has any idea to help me ? I already spent 2 weeks on that ! Have a nice day ! Julien

janjongboom · November 19, 2021, 12:31pm

Hi @Juph, can you remove the moving-average filter? You can do this by passing false here:

            EI_IMPULSE_ERROR r = run_classifier_continuous(&signal, &result, false, false);

Alternatively: if you see 0.4 max confidence, but don’t see many false positives you can lower the threshold here (change 0.7 to 0.4):

github.com

edgeimpulse/voice-activated-microbit/blob/cae1d7ffa3d2197d7fa1fb64ff0aac58b77511bf/source/MicrophoneInferenceTest.cpp#L157


if (++print_results >= 0) {
    // print the predictions
    ei_printf("Predictions (DSP: %d ms., Classification: %d ms.): \n",
        result.timing.dsp, result.timing.classification);
    for (size_t ix = 0; ix < EI_CLASSIFIER_LABEL_COUNT; ix++) {
        ei_printf("    %s: ", result.classification[ix].label);
        ei_printf_float(result.classification[ix].value);
        ei_printf("\n");
        if (strcmp(result.classification[ix].label, INFERENCING_KEYWORD) == 0 && result.classification[ix].value > 0.7) {
            heard_keyword_this_window = true;
        }
    }
    last_keywords = last_keywords << 1 & 0x1f;
    if (heard_keyword_this_window) {
        last_keywords += 1;
    }

Juph · November 19, 2021, 3:52pm

Thanks so much @janjongboom for your help! It works now with lower confidence threshold (0.4). I can now go to the weekend with good mood !

It is already ‘false’ originally in your code.

I think there is something wrong with the microbit microphone level, how to increase the microphone sensitivity, I have to be closed enough to make it work (approx 30 cm from the microphone). Is there anyway to increase the microphone sensitivity allowing to keep higher confidence level to avoid false detection ? Have a nice week-end. Julien

janjongboom · November 19, 2021, 4:15pm

@Juph There’s one false already but you want another one (first false is for debugging, second for moving average filter).

Is there anyway to increase the microphone sensitivity allowing to keep higher confidence level to avoid false detection

Good question, I don’t have the code in front of me, but I’d search the repository for ‘gain’. That’s typically how you control this…