Travelers at sea take soundings to measure the depth of the water through which they move. This kind of deep listening is necessary if they are to safely navigate treacherous waters. This is what we do as well, whenever we quiet ourselves and go to that inner place where there is enough silence for the words to resound.
The fitness of our hearts and thoughts to receive God's spirit is like that of violin strings. If they are properly tuned, in harmony with one another, then the touch of the bow produces beautiful music. If not, then there is only discord. Whenever our hearts are truly ready to receive God's spirit, they will produce heavenly airs and joyous harmonies -- both in this life and in the spiritual world.