Speech is not being recognized with default dictation grammar in my UWP application.

问题

Speech is not being recognized with default dictation grammar in my UWP application. However, it is perfectly recognized when I use programmatic list constraint. Below is the speech recognition part of my code for reference. If I do not comment the 5th line, this works fine. Am I doing something wrong below:

            speechRecognizer = new SpeechRecognizer();
            bool PermissionGained = await CheckMicrophonePermission();
            if (PermissionGained)
            {
               //speechRecognizer.Constraints.Add(new SpeechRecognitionListConstraint(Grammar.GrammarCommands.GrammarConstraintList));
               await speechRecognizer.CompileConstraintsAsync();

                //recognize speech input at any point of time 
                speechRecognizer.ContinuousRecognitionSession.ResultGenerated +=
                    async (s, e1) =>
                    {
                        if ((e1.Result != null)) 
                        {
                            await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                                async () =>
                                {
                                    await ParsespeechCommand(e1.Result);

                                });
                             speechRecognizer.ContinuousRecognitionSession.Resume();
                        }
                    };
                await speechRecognizer.ContinuousRecognitionSession.StartAsync(SpeechContinuousRecognitionMode.PauseOnRecognition);
            }

回答1:

As discussed I made a demo and made some changes from the codes. Here are my codes:

private async void myBtn_Click(object sender, RoutedEventArgs e)
{
        //here I remove the checkPermission process
        var speechRecognizer = new SpeechRecognizer();
        if (true)
        {
            //speechRecognizer.Constraints.Add(new SpeechRecognitionListConstraint(new List<string> { "winffee", "Elvis", "noob" }));
            await speechRecognizer.CompileConstraintsAsync();

            //recognize speech input at any point of time 
            speechRecognizer.ContinuousRecognitionSession.ResultGenerated +=
                async (s, e1) =>
                {
                    if ((e1.Result != null))
                    {
                        await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                            () =>//here I remove the async
                            {
                                var result = e1.Result;//here I remove the method to focus on the e1.Result.
                            });
                        speechRecognizer.ContinuousRecognitionSession.Resume();
                    }
                };
            await speechRecognizer.ContinuousRecognitionSession.StartAsync(SpeechContinuousRecognitionMode.PauseOnRecognition);
        }
}

The whole function is triggered by a button click event. And I made comment on every change position(totally 3 places).

来源：https://stackoverflow.com/questions/36996184/speech-is-not-being-recognized-with-default-dictation-grammar-in-my-uwp-applicat