Where is the mic located on Samsung Galaxy S2 I have downloaded an app for calculating distance of the phone to the wall It is known as sonar. I want to test this app. So, I covered the speakers 

of the phone which could be could found on the back side at the bottom of the phone.On doing so the app showed noticeable change in the distance calculated. However, I could not find the mic's exact location. I want to cover up the mic, and would like to observe any noticeable distance change. Then are couple of holes on the periphery of the phone, however, on closing each of them I could not find any noticeable. Can anybody show me in picture when can I exactly find the location of the mic. Thanks.
This is the mic on the Samsung Galaxy S2


And this is another mic on the top. In the user guide it says that it is a "mouthpiece" I presume by that they mean a microphone that is only active when you use the speakerphone feature or record videos or when the user is on a video call.