As I was reading through the text of the book of Exodus this summer, I noticed something regarding the two signs, which the LORD gave to Moses to perform in front of His people. Those two signs were aiming, not only, at mere confirmation of the truthfulness of the message (Exod 4:1-9), but also were to speak or to witness קוֹל a message to the hearers.
The usage of קוֹל (sound/voice), and the verb שׁמע (listen) in the phrase יִשְׁמְע֔וּ לְקֹ֖ל הָאֹ֣ת (Exod 4:8) translated by the NET Bible, “pay attention to the … sign” does not point to the meaning of the sign, but rather denotes “the voice”, the “noise” it causes. As if the signs cry loud to the people, “this is supernatural, this is divine, and you got to believe.”
Therefore, these signs were to accompany Moses’ words, in order to witness to the divine origin of the salvation he proclaims. The Signs were a voice, a trumpet that this Salvation is both true and divine.
In fact, this pattern is similar to Jesus’ proclamation of salvation (John 10: 36-38). A proclamation that was accompanied by marvelous signs to witness to the Divinity of Jesus and the truthfulness and seriousness of His Salvation. Of course I need to do further study to confirm/refute this interpretation. Nonetheless, I thought it is worth sharing so far.