Результат NAudio fft дает интенсивность на всех частотах C#

проблема заключалась в том, как я обрабатывал массивы данных. Работает как по маслу.

код (удален избыток и, возможно, добавлены ошибки):

// Other inputs are also usable. Just look through the NAudio library.
private IWaveIn waveIn; 
private static int fftLength = 8192; // NAudio fft wants powers of two!

// There might be a sample aggregator in NAudio somewhere but I made a variation for my needs
private SampleAggregator sampleAggregator = new SampleAggregator(fftLength);

public Main()
{
    sampleAggregator.FftCalculated += new EventHandler<FftEventArgs>(FftCalculated);
    sampleAggregator.PerformFFT = true;

    // Here you decide what you want to use as the waveIn.
    // There are many options in NAudio and you can use other streams/files.
    // Note that the code varies for each different source.
    waveIn = new WasapiLoopbackCapture(); 

    waveIn.DataAvailable += OnDataAvailable;

    waveIn.StartRecording();
}

void OnDataAvailable(object sender, WaveInEventArgs e)
{
    if (this.InvokeRequired)
    {
        this.BeginInvoke(new EventHandler<WaveInEventArgs>(OnDataAvailable), sender, e);
    }
    else
    {
        byte[] buffer = e.Buffer;
        int bytesRecorded = e.BytesRecorded;
        int bufferIncrement = waveIn.WaveFormat.BlockAlign;

        for (int index = 0; index < bytesRecorded; index += bufferIncrement)
        {
            float sample32 = BitConverter.ToSingle(buffer, index);
            sampleAggregator.Add(sample32);
        }
    }
}

void FftCalculated(object sender, FftEventArgs e)
{
    // Do something with e.result!
}

и класс агрегатора выборки:

using NAudio.Dsp; // The Complex and FFT are here!

class SampleAggregator
{
    // FFT
    public event EventHandler<FftEventArgs> FftCalculated;
    public bool PerformFFT { get; set; }

    // This Complex is NAudio's own! 
    private Complex[] fftBuffer;
    private FftEventArgs fftArgs;
    private int fftPos;
    private int fftLength;
    private int m;

    public SampleAggregator(int fftLength)
    {
        if (!IsPowerOfTwo(fftLength))
        {
            throw new ArgumentException("FFT Length must be a power of two");
        }
        this.m = (int)Math.Log(fftLength, 2.0);
        this.fftLength = fftLength;
        this.fftBuffer = new Complex[fftLength];
        this.fftArgs = new FftEventArgs(fftBuffer);
    }

    bool IsPowerOfTwo(int x)
    {
        return (x & (x - 1)) == 0;
    }

    public void Add(float value)
    {
        if (PerformFFT && FftCalculated != null)
        {
            // Remember the window function! There are many others as well.
            fftBuffer[fftPos].X = (float)(value * FastFourierTransform.HammingWindow(fftPos, fftLength));
            fftBuffer[fftPos].Y = 0; // This is always zero with audio.
            fftPos++;
            if (fftPos >= fftLength)
            {
                fftPos = 0;
                FastFourierTransform.FFT(true, m, fftBuffer);
                FftCalculated(this, fftArgs);
            }
        }
    }
}

public class FftEventArgs : EventArgs
{
    [DebuggerStepThrough]
    public FftEventArgs(Complex[] result)
    {
        this.Result = result;
    }
    public Complex[] Result { get; private set; }
}

и это все, что я думаю. Возможно, я что-то упустил. Надеюсь, это поможет!