Close your eyes. In general, you hear more when your eyes are closed or when you can’t see well (as when walking in the dark). Vision – translating light waves into familiar images – takes up a lot of brain power. Turn it off, and your mind has more resources to devote to the other senses
Spend an hour in a completely silent place. You’ll notice that your hearing will gradually become more acute. That’s because constant noise over-stimulates the delicate nerves that register sound.
Practice listening. Sitting in a quiet spot, try to identify all the sounds around you and direction each comes from. Most people can detect more sounds coming from in front of them than from behind.