文本转语音不适用于不同的Android手机

Question

我正在使用来自https://developer.xamarin.com/guides/xamarin-forms/application-fundamentals/dependency-service/text-to-speech/的精确Android实现代码和相同的共享代码示例DependencyService.Get<ITextToSpeech>().Speak("Hello from Xamarin Forms"); 问题是它适用于Visual Studio安卓模拟器和我的华为P9，但它不起作用（它编译，但它应该说话，而不是它保持沉默）在三星S6或我的朋友其他手机。有谁知道可能导致问题的原因？

[assembly: Dependency(typeof(TextToSpeechImplementation))]
namespace DependencyServiceSample.Droid
{

public class TextToSpeechImplementation : Java.Lang.Object, ITextToSpeech, TextToSpeech.IOnInitListener
{
    TextToSpeech speaker;
    string toSpeak;

    public void Speak(string text)
    {
        toSpeak = text;
        if (speaker == null)
        {
            speaker = new TextToSpeech(Forms.Context, this);
        }
        else
        {
            speaker.Speak(toSpeak, QueueMode.Flush, null, null);
        }
    }

    public void OnInit(OperationResult status)
    {
        if (status.Equals(OperationResult.Success))
        {
            speaker.Speak(toSpeak, QueueMode.Flush, null, null);
        }
    }
}

}