To understand hearing loss, you must first know a little about how the ear works. The human ear is a remarkably complex sound analyzing system, capable of detecting sounds over an incredibly wide range of intensity and frequency.
We usually describe the ear in three main sections: the outer ear, the middle ear and the inner ear. The outer ear serves as a sound collector. Sound vibrations cause movement of the eardrum which is connected to a chain of three tiny bones in the middle ear. The middle ear system serves to intensify the energy of the sound vibrations and delivers them to the cochlea in the inner ear. The cochlea is the actual organ of hearing. Inside the cochlea are thousands of hair-like cells that are connected to fibers of the hearing nerve. These hair cells are sensitive to different frequencies and intensities of sound.
Sound vibrations entering the cochlea cause the hair cells to generate electrochemical signals which travel through the hearing nerve to the brain where they are recognized as sounds.
A person with normal hearing can hear everything from the faintest whisper of the breeze to the roaring of a jet engine taking off. Normal hearing alerts us to dangers – our ears can give us information about the location and speed of an approaching car, for instance. With good hearing we are able to listen selectively, focusing on one conversation at a loud party and shifting easily to another conversation without missing a word. We are able to appreciate the beauty of a string quartet and the sound of a loved one’s voice.