Sound Detector

const long sample_rate = 50; // time between samples (in miliseconds)
const int array_size = 1200; // 1000/50=20 * 60=1200
int snd_array[array_size] = {};
int snd_max, prev_max = 10000;
int snd_min, prev_min = 4096;
double snd_avg = 2048;

const int blink_thresh = 2048;

unsigned long broadcast_interval = 3000;
unsigned long last_broadcast = 0;

void averageReading(int value) {

    // Shift all the values right by 1
    for(int i = array_size-1; i >= 1; i--) {
        snd_array[i] = snd_array[i-1]; 
    }

    snd_array[0] = value; // add new value to the first position in the array // NOPE

       // Average array
    float avg_sum = 0; 
    for (int a=0; a <= array_size; a++) {
        avg_sum  = avg_sum + snd_array[a];
    }
    //Serial.println("out of average loop") ;
    snd_avg = avg_sum / array_size;
}

void minReading(int value) {
    if(value < prev_min) { 
        snd_min = prev_min = value;
    }
}

void maxReading(int value) {
    if(value > prev_max) { 
        snd_max = prev_max = value;
    }
}

void blinkMic(int reading) {
    if(reading > blink_thresh) {
        digitalWrite(D7, HIGH);
    } else {
        digitalWrite(D7, LOW);
    }
}


void checkBroadcast() {
    unsigned long now = millis();
    if((now - last_broadcast) > broadcast_interval) {
        Serial.print("Avg: "); Serial.println(snd_avg);
        Serial.print("Min: "); Serial.println(snd_min);
        Serial.print("Max: "); Serial.println(snd_max);
        snd_avg = 10000;
        snd_min = 4096;
        snd_max = 0;
        snd_array[array_size] = {};
        last_broadcast = now;
    }
}

void setup() {
    Serial.begin(9600);
    pinMode(A0, INPUT); // mic AUD connected to Analog pin 0
    pinMode(D7, OUTPUT); // flash on-board LED
    Particle.variable("sound", snd_avg);
}

void loop() {
    int mic_reading = analogRead(0); //Serial.println(mic_reading);
    blinkMic(mic_reading);
    minReading(mic_reading);
    averageReading(mic_reading); 
    Serial.println("average: "+ String(snd_avg)) ;
    
    checkBroadcast();

    delay(sample_rate);
}