i have been trying to calculate the decible amount of microphone with help from online that i tried to use to help me there would always be an issue the decible is always some negitive number when it is very loud please help me with this i am trying to make a game were people are competing to make the most noise

i tried some code i found in another forum:

GetComponent<AudioSource>().GetOutputData(_samples, 0); // fill array with samples
int i;
float sum = 0;
for (i = 0; i < QSamples; i++)
{
    sum += _samples[i] * _samples[i]; // sum squared samples
}
rmsVal = Mathf.Sqrt(sum / QSamples); // rms = square root of average
dbVal = 20 * Mathf.Log10(rmsVal / RefValue); // calculate dB
if (dbVal < -160) dbVal = -160; // clamp it to -160dB min
                                // get sound spectrum
GetComponent<AudioSource>().GetSpectrumData(_spectrum, 0, FFTWindow.BlackmanHarris);
float maxV = 0;
var maxN = 0;
for (i = 0; i < QSamples; i++)
{ // find max 
    if (!(_spectrum[i] > maxV) || !(_spectrum[i] > Threshold))
        continue;

    maxV = _spectrum[i];
    maxN = i; // maxN is the index of max
}
float freqN = maxN; // pass the index to a float variable
if (maxN > 0 && maxN < QSamples - 1)
{ // interpolate index using neighbours
    var dL = _spectrum[maxN - 1] / _spectrum[maxN];
    var dR = _spectrum[maxN + 1] / _spectrum[maxN];
    freqN += 0.5f * (dR * dR - dL * dL);
}
pitchVal = freqN * (_fSample / 2) / QSamples; // convert index to frequency

i expected it to work but it just returns -160 always i dont know why