I read somewhere that Rishis were mantra dristas, and also that Rishis heard the mantras in Samadhi. Later on, Rishi Ved Vyasa compiled these mantras in four Vedas.
Now, the question is, in which language did Rishis see or hear the mantras?
Pratyahar is one of the eight limbs of Ashtang Yog. In this, the yogis stop using the indriyas/outward senses. Indriyas give us outside information. The flow of information is from outside to inside.
In Pratyahar, the senses go outward from the inside. It means Rishis did not hear or see anything when they were in Samadhi. They just understood or felt these mantras. Most likely, the perception was from inside, not from outside.
There is a saying- Yatha pinde tatha brahmande. Means whatever exists outside exists inside our body. so, mantras may have emanated from inside Rishis when they were in Samadhi. There was no seeing or hearing involved.
Bharti Raizada