It is possible to hear without a human preacher. Enoch, Noah, Abraham, King David, all the prophets, Jesus and the Apostles all heard with without a human preaching; that is actually understanding revealed spiritual knowledge. Today, we have no need for human preachers because the Holy Spirit of the Father through Jesus the mediator is how Christians learn. Anyone who learns spiritual truth learns it by the spirit of God. John 6:37 , John 14:6 , Matthew 11:27 , John 6:45 , 1John 2:27 , 1 Thessalonians 4:9 , Hebrews 8:11 The teacher is and always has been the spirit of God. Preaching was to the worldly people and if God desires to call them HE will open their minds to understand so that they will be cut to the heart, spirituality circumcised, producing Godly sorrow that leads to repentance and then conversion. Look at the massive confusion in the world that drowns and smothers the truth. Which one of the 55,000 churches out there is the true church? If you studied each one for one year to see if they are the true church it would take 55,000 years to go through them all. Satan's attack on the church has all but destroyed the truth except in a very small remnant.