Teresa of Avila, a contemporary of John of the Cross, and the Doctor of Prayer in the Catholic church, wrote extensively on how to hear the voice of God, mainly by looking at the effect the inner hearing would have on the heart. She echoes the sentiment of John of the Cross, that it requires maturity to weigh the voice of God.
In her seminal work, Interior Castles, Teresa has the soul moving through seven stages of purification. It is not until the sixth stage that she even begins talking about hearing the voice of God. Why? Because peace and quiet must settle into the inner life before the voice of God can be easily discerned.
The labor of the spiritual life (service, silence, solitude, prayer, etc…) over time settles the heart into extended quietude. AS we discipline ourselves to approach God, we set our mind (the form of our being) upon Him. The result of this focus is that peace begins to reign in the inner life. (see our course series on Preparing Your Heart)
'You will keep him in perfect peace, whose mind is stayed on You,
because he trusts in You.’ Isaiah 26:3