public Task SpeechAsync(string text, string language = null)
{
CrossLocale?locale = null;
if (language != null)
{
locale = synthesizer.GetInstalledLanguages().FirstOrDefault(l => l.Language.StartsWith(language));
locale = locale.Value.Language != null ? locale : null;
}
synthesizer.Speak(text, crossLocale: locale);
return(Task.FromResult <object>(null));
}