Audio visualizer in unity with blend shapes

AudioVisualizer.cs

using UnityEngine;

[RequireComponent(typeof(SkinnedMeshRenderer))]
public class AudioVisualizer : MonoBehaviour 
{
    [Range(1.0f,4500.0f)]
    public float multiplier;
    public int minRange = 0;
    public int maxRange = 64;
    private SkinnedMeshRenderer skinnedMeshRenderer;
    private float prevAvg = 0.0f;
	void Start () 
    {
        skinnedMeshRenderer = GetComponent<SkinnedMeshRenderer> ();
	}	
	void Update () 
    {        
        float[] spectrum = new float[64];
        AudioListener.GetSpectrumData(spectrum, 0, FFTWindow.BlackmanHarris);
        if (maxRange < minRange)
            maxRange = minRange + 1;
        minRange = Mathf.Clamp(minRange, 0, 63);
        maxRange = Mathf.Clamp(maxRange, 0, 63);
        float avg = 0;
        for (int i = minRange; i < maxRange; i++)
            avg += Mathf.Abs(spectrum[i]);        
        avg = avg / (float)Mathf.Abs(maxRange - minRange);
        if (avg - prevAvg > 0.0012f)
            avg = prevAvg + 0.0012f;
        else if (avg - prevAvg < -0.0012f)
            avg = prevAvg - 0.0012f;
        skinnedMeshRenderer.SetBlendShapeWeight(0, avg*multiplier);
        prevAvg = avg;
	}
}