Although the “Drishti Yoga” (Yoga of Inner Light or Vision) is more difficult to accomplish than the “Shabda-yoga” (Yoga of Inner Sound), it is important to practice first the Yoga of Light to attain Single-pointedness….
Having attained Single-pointedness, the attention should be focused on the inner Sounds. The consciousness will, naturally, be drawn towards the inner Sounds, leaving the bindu (the Radiant Infinitesimal Point) behind. The extreme bliss experienced when hearing the inner Sounds completely absorbs the consciousness….
While meditating on the inner Sound it is possible for the practitioner to also see the Divine Light. Just as while attending a concert, one cannot help but see (the stage, artists, etc.), so also the spectacular scenes of the various Non-Conscious Realms also are seen inevitably when engaged in the practice of the Yoga of Sound. Hence, it has been remarked that “the Light is within the Sound”. Not surprisingly, the practice of the meditation upon the inner Sound may transport its practitioner into the Domain of Divine Light. The Sound, nonetheless, is of utmost importance, is the essence of the practice — and not grasping the Sound, therefore, would be the greatest loss.” (Maharshi Mehi Paramhans — translated into English by Pravesh K. Singh)