en_tn/exo/19/19.md

grew louder and louder

"continued to become louder and louder"

in a voice

The word "voice" here refers to a sound that God made. Possible meanings are 1) "by speaking loudly like thunder" or 2) "by speaking" or 3) "by causing thunder to sound" (See: rc://en/ta/man/jit/figs-metonymy)