For everything that was written in the past was written to teach us, so that through the endurance taught in the Scriptures and the encouragement they provide we might have hope. - Romans 15:4
Jesus identifies Himself as the good Shepherd, and the sons and daughters of God are His sheep. He declares in John 10:27 that His sheep have the innate ability to hear His voice. It is neither an acquired skill nor the exclusive right of an elite group. Just like how we can hear with our physical ears, it has always been a natural ability.