For a few rare souls, the Lord speaks to them aloud or clearly to their heart. For the rest of us, the Holy Spirit often plants a thought in our mind. But the Lord speaks in silence too. Even though you do not hear anything, things develop in such a way that you know he has heard you. This is like the silent rests written into a piece of music. Even though you do not hear them, they are still played. Therefore, pray and trust.