Tinnitus is an auditory phenomenon. In order to begin to understand tinnitus, you must understand how the auditory system works. My job is to teach you enough about the human auditory system to assist in this process. Chronic tinnitus almost always occurs with some sort of dysfunction of the auditory system, so we’ll explore the various types and causes of hearing loss. Our sense of hearing connects us to the world and is especially important for communication, socializing and learning. Even a mild form of hearing loss can have a significant impact on communication and lifestyle, and so we’ll discuss the various effects of hearing loss on daily life. And finally, because this book is about tinnitus, we’ll consider the relationship between hearing loss and tinnitus.

Consider early man living in the woods. Basic survival depended on his ability to be constantly aware of approaching danger, like a predator animal (or possibly a cranky neighbor into whose territory he accidentally stumbled). The snap of a twig would elicit an immediate head turn in the direction of the sound, and send signals through the man’s body to be ready to fight or flee. His heart rate and breathing would quicken; blood would rush to his extremities; his other senses (vision and smell) would be heightened. All of this because an unexpected sound picked up by the human ear was enhanced by the “subconscious” part of the auditory system. Now, the signal reaches the conscious part of the auditory system - the brain - and the man recognizes the sound as that of an animal running. At about the same moment, the man turns to see that his favorite dog has followed him into the woods. He takes a deep breath, relaxes, and yells at his dog for sneaking up on him like that. As they carry on through the woods, the sound of the dog’s running feet drifts back into the man’s subconscious, no longer considered important to pay attention to.

The same scenario could happen to you, modern man (or woman). Picture yourself walking down a dark street in an unfamiliar neighborhood. As you pass by an alleyway, there’s a sudden scuffling noise. Your auditory system prepares you just as it did the caveman, but this time you also grab on tight to your wallet or purse as you get ready to run (a more recent adaptation for survival). Happily, it’s just a stray dog so you can relax.

So I think you get my point. Our hearing is essential to our survival. However, in modern times, the higher order functions of hearing are more obviously beneficial to our way of life. As infants, we begin to develop language by hearing the same speech sounds over and over. We eventually learn the patterns of speech that lead to the meaning of words. Throughout our lives, we continue to use sound to learn and understand our world. Hearing connects us to our environment and to other people. It’s our primary means of social connection. If we lose even a small amount of hearing, it can have an effect on our social interactions and our sense of well-being. The additional effort required to carry on a conversation with impaired hearing can be quite stressful. Tinnitus is often an early sign of hearing loss.