// read a bunch of samples:
      int samples[SAMPLES];

      for (int i=0; i<SAMPLES; i++) {
        int sample = 0;
        while ((sample == 0) || (sample == -1) ) {
          sample = I2S.read();
        }
        // convert to 18 bit signed
        sample >>= 14;
        samples[i] = sample;
      }

      // ok we hvae the samples, get the mean (avg)
      float meanval = 0;
      for (int i=0; i<SAMPLES; i++) {
        meanval += samples[i];
      }
      meanval /= SAMPLES;
      //Serial.print("# average: " ); Serial.println(meanval);

      // subtract it from all sapmles to get a 'normalized' output
      for (int i=0; i<SAMPLES; i++) {
        samples[i] -= meanval;
        //Serial.println(samples[i]);
      }

      // find the 'peak to peak' max
      float maxsample, minsample;
      minsample = 100000;
      maxsample = -100000;
      for (int i=0; i<SAMPLES; i++) {
        minsample = min(minsample, samples[i]);
        maxsample = max(maxsample, samples[i]);
      }