Added check, in case coroutine was already running, to yeild break if called again.

Author: StephenHodgson

Assets/HoloToolkit/Input/Scripts/Microphone/DictationInputManager.cs

@@ -126,6 +126,8 @@ public static int RecordingTime
 
         private bool hasFailed;
 
+        private static bool isListening;
+
         #region Unity Methods
 
         protected override void Awake()
@@ -182,6 +184,10 @@ protected override void OnDestroy()
         /// </summary>
         public static IEnumerator StartRecording()
         {
+            if (isListening) { yield break; }
+
+            isListening = true;
+
             if (PhraseRecognitionSystem.Status == SpeechSystemStatus.Running)
             {
                 PhraseRecognitionSystem.Shutdown();
@@ -209,13 +215,18 @@ public static IEnumerator StartRecording()
 
             // Start recording from the microphone.
             dictationAudioClip = Microphone.Start(DeviceName, false, RecordingTime, samplingRate);
+
         }
 
         /// <summary>
         /// Ends the recording session.
         /// </summary>
         public static IEnumerator StopRecording()
         {
+            if (!isListening) { yield break; }
+
+            isListening = false;
+
             Microphone.End(DeviceName);
 
             if (dictationRecognizer.Status == SpeechSystemStatus.Running)