C# Code for Synthesizing Nes Noise: The result is different from the real Nes noise!

Code:

using System;using System.IO;using System.Media;using System.Collections.Generic;public class NoiseGenerator{    // Noise period table (NTSC non - short mode)    private static readonly ushort[] NoisePeriodsNTSC = { 4, 8, 16, 32, 64, 96, 128, 160, 202, 254, 380, 508, 762, 1016, 2034, 4068 };    private const double NTSCBaseFreq = 1789773.0;    // Core algorithm for generating noise    private static short[] GenerateNoiseSegment(int index, bool shortMode, double durationSec, int sampleRate)    {        int period = NoisePeriodsNTSC[index];        int samples = (int)(durationSec * sampleRate);        short[] buffer = new short[samples];        ushort shiftReg = 1;        int sampleRateMode = shortMode ? 8 : 13;        // Accurate period calculation (based on APU clock)        double clockRate = NTSCBaseFreq;  // 1.789773 MHz        // Correct frequency calculation, considering the impact of sampleRateMode on frequency        double cyclesPerSample = clockRate / sampleRate / (sampleRateMode == 8 ? 2 : 1);        double noiseCycles = 0;        for (int i = 0; i < samples; i++)        {            int cyclesToRun = (int)(cyclesPerSample + noiseCycles);            noiseCycles = (cyclesPerSample + noiseCycles) - cyclesToRun;            while (cyclesToRun-- > 0)            {                if (--period <= 0)                {                    period = NoisePeriodsNTSC[index];                    ushort bit14 = (ushort)((shiftReg << 14) & 0x4000);                    ushort bitSR = (ushort)((shiftReg << sampleRateMode) & 0x7FFF);                    ushort newBit = (ushort)((bit14 ^ bitSR) & 0x4000);                    shiftReg = (ushort)((newBit | (shiftReg >> 1)) & 0x7FFF);                }            }            buffer[i] = (short)((shiftReg & 1) != 0 ? 5000 : -5000);        }        return buffer;    }    // Generate the WAV file header    private static byte[] CreateWavHeader(int dataSize, int sampleRate)    {        using (MemoryStream ms = new MemoryStream())        using (BinaryWriter writer = new BinaryWriter(ms))        {            writer.Write("RIFF".ToCharArray());            writer.Write(36 + dataSize);          // Total file size            writer.Write("WAVEfmt ".ToCharArray());            writer.Write(16);                     // fmt chunk size            writer.Write((ushort)1);              // PCM format            writer.Write((ushort)1);              // Mono channel            writer.Write(sampleRate);             // Sample rate            writer.Write(sampleRate * 2);         // Byte rate            writer.Write((ushort)2);              // Block alignment            writer.Write((ushort)16);             // Bit depth            writer.Write("data".ToCharArray());            writer.Write(dataSize);               // Data size            return ms.ToArray();        }    }    public static void Main()    {        const int sampleRate = 44100;        const double duration = 0.5;        List<short[]> noiseSegments = new List<short[]>();        // Generate 16 frequencies in non - short mode (13 - bit shift)        for (int i = 0; i < NoisePeriodsNTSC.Length; i++)        {            noiseSegments.Add(GenerateNoiseSegment(i, false, duration, sampleRate));        }        // Generate 16 frequencies in short mode (8 - bit shift) (using the same period table)        for (int i = 0; i < NoisePeriodsNTSC.Length; i++)        {            noiseSegments.Add(GenerateNoiseSegment(i, true, duration, sampleRate));        }        // Merge all audio data        List<short> fullAudio = new List<short>();        foreach (var segment in noiseSegments)        {            fullAudio.AddRange(segment);        }        // Generate the WAV file        byte[] pcmBytes = new byte[fullAudio.Count * 2];        Buffer.BlockCopy(fullAudio.ToArray(), 0, pcmBytes, 0, pcmBytes.Length);        byte[] wavHeader = CreateWavHeader(pcmBytes.Length, sampleRate);        using (MemoryStream wavStream = new MemoryStream())        {            wavStream.Write(wavHeader, 0, wavHeader.Length);            wavStream.Write(pcmBytes, 0, pcmBytes.Length);            wavStream.Position = 0;            new SoundPlayer(wavStream).PlaySync();        }    }}