Isaiah 6:8
Also I heard the voice of the Lord, saying:
“Whom shall I send, And who will go for Us?”
Then I said, “Here am I! Send me.”

With his sin purged, Isaiah is ready, willing, and able for the service of the Lord.
“Here am I! Send me” is his response.
This is the first time in this chapter he’s heard the voice of Yahweh.
He saw God’s glory fill the temple.
He heard the Seraphim glorify God and shake the pillars of the place.
A Seraphim touched a coal to his lips but this is the first time Isaiah heard God.
Sin in your life hampers you from hearing God. When sin is purged then God will talk and you will hear.
That isn’t to say God never spoke but it is to say the Isaiah never heard.
If you can’t hear from God, please examine your state. Perhaps God is speaking and sin makes you deaf.