The travelling Soul
When traversing into the higher planes, the soul experiences Light and Sound. The first step, of course is to withdraw from the physical body and be born anew into the beyond. You will be able to go along the Way inside if you but follow the instructions implicitly which were given to you at the time of initiation. The Sound and Light meet the travelling soul on the way up. This is the right form of meditation.
If you put in time doing the prescribed Spiritual Practices, you will withdraw inside and your Inner Vision will open. The Light of heaven will begin to be visible to you in different colours. This Light is seen when the soul withdraws completely from the body and goes out of sight when we again become conscious of the physical body.
The fact, as you say, that you come to the point of being almost unconscious of your physical body shows that you withdraw from the body to that extent. At that time the Light becomes visible to you and you also hear the Sound of the bell clearly. You have to develop this by giving time accurately in a regular way. Try to fix your gaze constantly, and further things will follow and Master will appear to you in due course.