As many of you meanwhile know, phosphenes are the door to the mystic perception of who we really are. They are the stepstones which lead you into recognizing who you really are. I have experimented with phosphenes quite some time now, in silent meditations, in hypnogogic sleep and during meditative music.

Phosphenes, the subtle light phenomena that arise in darkness or stillness without external visual stimulation, have been central to the Yoga of the Inner Light. Often described as glowing, geometric, or kaleidoscopic, they provide an inner landscape that responds mysteriously to consciousness. While classically explored through stillness and gaze, there is growing experiential and scientific evidence that sound, especially simple, sustained tones can enhance the phosphene experience.

A steady vibrational field

In personal meditative practice, it becomes clear that certain drone-like tones, such as those produced by a srutibox or the Pythagorean monochord, have the capacity to intensify phosphenes. These continuous, resonance-rich tones do not provide rhythm or melody in the traditional sense, but rather create a steady vibrational field. When the mind is calm and the eyes are closed, this field seems to entrain perception. Phosphenes become more vivid, more coherent, and even seem to move or stabilize in response to tonal shifts.

What might be dismissed as anecdotal has recently found strong scientific support. A study on multisensory integration revealed that auditory stimuli can significantly enhance the perception of phosphenes, particularly those induced by transcranial magnetic stimulation (TMS) to the visual cortex. This study demonstrated that when a brief sound is delivered in close spatial and temporal proximity to a TMS pulse, even subthreshold stimulation — which would not normally produce a visible phosphene, is amplified by the presence of sound. The phosphene appears. Sound has raised the visual cortex to perceptual threshold.

The most striking result was that the auditory stimulus was most effective when it preceded the visual stimulation by 40 milliseconds, pointing to a precise temporal window of crossmodal facilitation. This supports the idea that the senses do not process independently and only converge at higher levels of the brain, as once thought. Instead, the unisensory cortices themselves are dynamically interconnected and can modulate each other’s excitability.

This is not limited to high-level cognitive functions. The early sensory cortices, once considered modular and encapsulated, are now known to be sensitive to contextual and crossmodal cues. Sound does not just “accompany” the inner light, it can shape it.

In practice, this means that a tone from a srutibox or monochord is not merely auditory. When combined with inner silence, darkness, and directed presence, it becomes a vibrational guide, facilitating visual excitability in the occipital cortex. Phosphenes are not hallucinations in this model, they are intermodal expressions of an inner network that responds to subtle attentional and sensory shifts.

Furthermore, the meditative experience of watching the light while immersed in a drone tone closely matches the neurophysiological pattern of a low-stimulus, crossmodally enhanced cortical state. This may also explain why certain mantras, overtone singing, and extended vowel chanting — all of which generate harmonics and resonance — are reported across traditions to deepen visionary states.

The deeper implication is this: light and sound may be two aspects of the same inner perception. Not as poetic metaphor, but as functional interpenetration within the architecture of perception. The Yoga of the Inner Light, when joined with the Yoga of Sacred Sound (NADA), may become not two practices, but one unfolding. Shunyam Adhibhu