Nadabindu and Dhyanabindu Upanishads comprise Volume 5 in the Yoga Upanishad series.
These Upanishads focus on meditation on the bindu, the source point or origin of individual creation, where begins the primal sound or first vibration, the mantra Om. They define and describe in detail the mantra Om, the effects of meditating on it until one attains perfect liberation, merging with the Divine.
Nadabindu states that always meditating on Om, the yogin is liberated from worldly life, unaffected by his/her karmas. The nada is first heard through the right ear, and many other inner sounds are heard. Eventually the yogin hears no other sounds and transcends duality.
Dhyanabindu, an expansion of Nadabindu, recommends many practices including mudras, bandhas, bija mantras and raising kundalini shakti.
This volume includes a foreword on the life and teachings of Swami Satyadharma, who passed away while writing her commentary on Dhyanabindu.