async void worker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = new BackgroundWorker();
string ssmlText = "<speak version=\"1.0\" ";
ssmlText += "xmlns=\"http://www.w3.org/2001/10/synthesis\" xml:lang=\"es-ES\">";
ssmlText += strTextoALeer;
ssmlText += "<mark name=\"fin\"/></speak>";
AppResources.ss.SpeakSsmlAsync(ssmlText);
await worker.RunWorkerTaskAsync();
}
