stopping wav files from playing after certain time

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C#

Hi
I'm trying to make a guitar player with c#. The design is finished, but the only thing that stands in my way for finishing this project is for letting the sound stop at a certain time.
So what i do is actually ask a couple of questions in my program, first the amount of beats per minute, the note and the beat(which is always in default 4/4).
i make a small calculation of how many seconds the note actually has to play:
time = beat*60/bpm;
this amount do i send to my function that plays the note:

private void playtab(int i, int j,long tijd)
{
    //MCI
    long t0 =  System.Environment.TickCount;
    long t1 = t0 + tijd*1000;
    //MCI
    string Playwav = pathname + _tabsnaam[i, j] + dataname;
    //mciSendString(PlaySound, null, 0, IntPtr.Zero);
    //SoundPlayer tabsound = new SoundPlayer(pathname + _tabsnaam[i, j] + dataname);
    Boolean gespeeld = true;
    while (gespeeld == true)
    {
        _tabs[i, j].BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(255)))), ((int)(((byte)(128)))), ((int)(((byte)(128)))));
        PlaySound(Playwav, new System.IntPtr(), PlaySoundFlags.SND_SYNC);
        //tabsound.PlaySync();
        if (System.Environment.TickCount >= t1 )
        {
           PlaySound(Playwav,new System.IntPtr(),PlaySoundFlags.SND_NOSTOP);
            _tabs[i, j].UseVisualStyleBackColor = true;
            gespeeld = false;
        }

    }
}

for play sound i use:

[System.Runtime.InteropServices.DllImport("winmm.DLL", EntryPoint = "PlaySound", SetLastError = true,/* CharSet = CharSet.Unicode,*/ ThrowOnUnmappableChar = true)]
        private static extern bool PlaySound(string szSound, System.IntPtr hMod, PlaySoundFlags flags);
        [System.Flags]
        public enum PlaySoundFlags : int
        {
            SND_SYNC = 0x0000,
            SND_ASYNC = 0x0001,
            SND_NODEFAULT = 0x0002,
            SND_LOOP = 0x0008,
            SND_NOSTOP = 0x0010,
            SND_NOWAIT = 0x00002000,
            SND_FILENAME = 0x00020000,
            SND_RESOURCE = 0x00040004
        }

can someone please tell me how i can make this work
thank you.