People can learn to navigate in the same way bats and dolphins do, by echolocation. Some blind people have become very proficient at this; there are some videos at this site of blind people who can pinpoint objects in a room and hit other people with thrown pillows. One blind man who has been studied by scientist can shoot a basketball with great accuracy.
Recent scientific studies of blind people who do this show that their hearing is not more acute than that of other people. They do not hear any more. They simply become aware of how to interpret certain signals that others ignore. Interestingly, MRI studies show that they use the visual cortex to process this information. It is the visual cortex, it seems that figures out where bodies are in space, not mater how the data comes in.
People have to learn to do this, through many hours of practice, and they find this much easier if they are hooked up with other blind people who also use this method. These studies are an extraordinary window into the flexibility and capability of the human mind, and they offer hope that many blind people can learn to navigate their worlds much more smoothly.