The ancient teachings of yoga tell us that we are all part of the energy of the universe and that the divine is within us. As humans, we are limited in our full understanding of this, but all the wise teachers say it is true. Meditation that involves chanting: either out loud, in silence, or as kirtan (devotional singing) help us to “lift the veil”, raise our vibration, and bring us closer to the divine energy within. All of this can help with clarity of thought, openness of heart and a feeling of peace and connection to a power greater than ourselves.
In the yoga classes that I teach, we chant the sacred sound of OHM (also spelled OM or AUM) at the completion of practice. OHM is a seed syllable and is said to be the mantra from which all else comes. It is first identified in the Upanishads which are early sacred texts from India. I am not a Sanskrit scholar but from my study and understanding, the sacred sound of OHM came from the ancient Rajis. They sat and listened to the vibrational quality of the universe. From there, this vibration took the form, word and sound of OHM. When we chant OHM during or after yoga class, we are raising our vibration to the energy of the universe. In meditation practice, chanting seed sounds and mantras are a tool to quiet and focus the mind providing one with a sense of calm, peace, mental clarity and a connection to a greater power. Is is said to be experienced like the vibration of a gong that gradually tapers to a point of silence.
The International Journal of Yoga published a study about chanting OHM : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9015091/