Close the ears and pull up the rectum, and then just remain with what is happening inside you. Just remain in that vacant state which is created by these two things. Your life energy is moving within and it has no way to go out. Sound goes out either from your ears or from your rectum. Those are the two doors from where the sound can move out. If is not moving out, you can feel it more easily.
And what will happen when you feel this inner sound? With the very phenomenon of hearing the inner sound, your thoughts dissolve.