Audio Fix my Mic Input

I am making an audio game called Cyrstal Ball on which the game uses mic input. I have an issue where it picks up microphone feedback whilst it's recording.How do I adjust this script so that the game will not pick up microphone whilst recording audio?

Code (CSharp):

1.   private void StartRecording()
2.     {
3.         source.outputAudioMixerGroup = mixer;
4.         Debug.Log("Total found mic : " + Microphone.devices.Length);
5.         source.clip = Microphone.Start(null, true, (int)recordingTimeToWaitInSecs, 22050);
6.         while (!(Microphone.GetPosition(null) > 0)) { }
7.         Debug.Log("start playing... position is " + Microphone.GetPosition(null));
8.         source.Play();

 

i didnt have issues when tested recording in android last time..

wasnt using mixer though, and i used first device name (instead of null),
also called microphone.end after recording..