C# Run Text To Speech Synth In New Thread To Keep UI Responsiveness?

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C#

Visual-Studio

VS2010

, +

Hello I have developed a program to speak the contents of a web page.
Here is the code i do this with:

public void SpeakSynthText(String TextToSpeak, bool SpeechRecognitionEnable)
{
    #region SpeechSynth
    if (SpeechRecognitionEnable == true)
    {
        //starts the speech engine
        this.Start();
    }


    // Initialize a new instance of the SpeechSynthesizer.
    SpeechSynthesizer synth = new SpeechSynthesizer();
    if (Boolean.Parse(SpeechSaveEnabled) == true)
    {
        //FolderDialogSaveSpeechToDirectory();
        SaveFileDialog saveFileDialog1 = new SaveFileDialog();
        saveFileDialog1.Filter = "wave files (*.wav)|*.wav|All files (*.*)|*.*";
        saveFileDialog1.FilterIndex = 1;
        saveFileDialog1.RestoreDirectory = true;

        if (saveFileDialog1.ShowDialog() == DialogResult.OK)
        {

            TB.SaveFile(saveFileDialog1.FileName, RichTextBoxStreamType.PlainText);
            WaveFileLoc = saveFileDialog1.FileName;
            synth.SetOutputToWaveFile(WaveFileLoc);
            synth.Rate = -1;

        }


    }
    // Select a voice that matches a specific gender.
    synth.SelectVoiceByHints(VoiceGender.Female);
    // Speak a text string synchronously and play back the output file.


    synth.Speak(TextToSpeak);
    synth.Dispose();
    //synth.SetOutputToWaveFile();
    verbalcommandmode = "true";
    if (Boolean.Parse(SpeechSaveEnabled) == true)
    {
        System.Media.SoundPlayer m_SoundPlayer =
        new System.Media.SoundPlayer(@WaveFileLoc);
        m_SoundPlayer.Play();
        m_SoundPlayer.Dispose();
    }
    #endregion
}

when i want to speak the contents of a web page i pass the arguments of:

this.SpeakSynthText(WIKI.Document.Body.InnerText, false);

now when i run this the UI freezes up until its done speaking, so i was told that i would have to run the function on a thread separate of the UI thread.
So i read all the articles i could find on codeproject and this is what i got:

private void SpeakPageText_Click(object sender, EventArgs e)
        {
            Thread t = new Thread(new ThreadStart(RunInThread));
            t.Start(); 

            //WIKI.Document.Body.InnerText

        }

this function(sorry i keep calling them functions i am used to coding in python) is called when i click the button associated with this method
when i run this method it is SUPPOSED to run the RunInThread method in a new thread. The RunInThread method goes like this:

public void RunInThread()
{

    //Option 1

    try
    {
        if (this.InvokeRequired)
        {
            this.Invoke(new EventHandler(delegate { this.SpeakSynthText(WIKI.Document.Body.InnerText, false); }));
        }
    }

    catch (InvalidOperationException oex)
    {
        MessageBox.Show(oex.Message);
    }

}

i have a feeling that it isn't running RunInThread on a separate thread but instead on the main thread, so how do run this method on a new thread?
or if that won't work how can i speak text with the speech synthesizer but not have the UI freeze up?
All of your help is very much appreciated.