Mantras are only endowed with transformative electrical power if presented in initiation (dīkṣa) in the mouth of the guru. It's not necessarily much suitable pronunciation, but rather the power with which the mantra is endowed that offers it reworking capacity. Both equally Vedic and Avestan mantras have several useful similarities. https://directoryhand.com/listings13291999/mantra-things-to-know-before-you-buy