O — third-eye resonance
Ājñā-region vowel
O is placed at the third-eye or ājñā region as the rounded, inward-turning vowel of AUM. The cranial projection is a school-dependent resonance convention rather than a direct statement of the Yoga Sūtras.
Point 6 of 8 in Nāda Yoga — Sound-Body Resonance Map
Cross-tradition overlaps
- O — third-eye resonance ↔ Third-eye chakra — A4 (distance 0.010)
Sources
Yoga Sūtras 1.27–29 (primary_canonical)
Praṇava contemplation is the textual basis for the AUM sequence.
Guy L. Beck, Sonic Theology: Hinduism and Sacred Sound (scholarly_modern)
Comparative analysis of OṂ and sacred sonic symbolism.