PDF Reading and Speaking using C# ASP.NET

private string ExtractTextFromPdf()
{
      if (fileUploadSelectFile.HasFile)
      {
            string filename = Server.MapPath(path: "~/FileToRead/") + fileUploadSelectFile.FileName.ToString();

            using (PdfReader reader = new PdfReader(filename))
            {
                 var text = new StringBuilder();

                 for (int i = 1; i <= reader.NumberOfPages; i++)
                 {
                        text.Append(PdfTextExtractor.GetTextFromPage(reader, i));
                 }
                 return text.ToString();
            }
       }
       else
       return "Please select file";
}
protected void btnSpeak_Click(object sender, EventArgs e)
{
       // creating the object of SpeechSynthesizer class
       string textToRead;
       textToRead = ExtractTextFromPdf();
       var speakMe = new SpeechSynthesizer();
       //setting volume
       speakMe.Volume = 100;
       //ing text box text to SpeakAsync method
       speakMe.SpeakAsync(textToRead);
}