how to use the voices of virtual assistants separately in c #?

Choices lista = new Choices();

lista.Add(new string[] { "Hola Helena" });

Grammar gramatica = new Grammar(new GrammarBuilder(lista));

try
{
     reconocedor.SetInputToDefaultAudioDevice();
     reconocedor.LoadGrammar(gramatica);
     reconocedor.SpeechRecognized += Reconoce;
     reconocedor.RecognizeAsync(RecognizeMode.Multiple);
}
catch (Exception)
{
     throw;
}
     Console.ReadLine();