GetAudioData from microphone and calculate pitch

GetAudioData.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Audio;

[RequireComponent(typeof(AudioSource))]
public class GetAudioData : MonoBehaviour {

    AudioSource _audioSource;

    // remember to create an audio mixer, create a subgroup on the master, set the new groups volume to -80 and attach it here!
    public AudioMixerGroup _audioMixerMic;

    public float rmsVal;
    public float dbVal;
    public float pitchVal;

    private const int QSamples = 1024;
    private const float RefValue = 0.1f;
    private const float Threshold = 0.02f;

    float[] _samples;
    private float[] _spectrum;
    private float _fSample;    

    bool isReady;

        // Use this for initialization
    void Start () {

        isReady  = false;

        _samples = new float[QSamples];
        _spectrum = new float[QSamples];
        _fSample = AudioSettings.outputSampleRate;

        _audioRange.fillAmount = 0;

        if (Microphone.devices.Length > 0) {
            _audioSource = GetComponent<AudioSource>();
            _audioSource.outputAudioMixerGroup = _audioMixerMic;
            _audioSource.clip = Microphone.Start(null, true, 10, 44100);
            _audioSource.loop = true;
            while (!(Microphone.GetPosition(null) > 0)) {
                _audioSource.Play();
            }

            isReady = true;
        }

    }

    void Update() {
        if(isReady) {
            AnalyzeSound();
        }
    }

    void AnalyzeSound() {
        _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
        _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
    }

}