The Psychology and Stages of the Hearing Process
Our hearing system provides us with an amazing ability to identify and comprehend even the most minuscule acoustic cues. Our hearing process truly connects us to the soundscape of our surrounding environment. In fact, our brains are capable of storing the neural equivalents of acoustic patterns like music, voices, danger sounds, and environmental sounds.
When your hearing is working as it should, signals and information are processed through various parts of the ear and go up the auditory nerve to the brain. When you’re experiencing problems with your hearing, determining which part of the hearing system is failing to respond is the first step to improving your health and quality of life.
Hearing depends on a series of complex steps that change sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain.
The Stages of Hearing
The hearing process can be broken down into several key stages:
- Sound Waves Enter the Ear: The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear.
- Amplification in the Middle Ear: The bones in the middle ear amplify, or increase, the sound vibrations. The vibrations are then sent to the cochlea, a snail-shaped structure filled with fluid, in the inner ear.
- Fluid Movement in the Cochlea: An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. Once the vibrations cause the fluid inside the cochlea to ripple, a traveling wave forms along the basilar membrane.
- Hair Cell Activation: Hair cells-sensory cells sitting on top of the basilar membrane-ride the wave. As the hair cells move up and down, microscopic hair-like projections (known as stereocilia) that perch on top of the hair cells bump against an overlying structure and bend.
- Signal Creation: Bending causes pore-like channels, which are at the tips of the stereocilia, to open up. Movement of fluid in turn makes the hair cells.
- Auditory Nerve Transmission: The auditory nerve picks up any neural signals created by the hair cells.
- Brain Interpretation: The auditory nerve moves signals to the brain where they are then translated into recognizable and meaningful sounds.
Hearing Loss and Its Impact
Hearing loss occurs when sounds that are typically loud become softer and less intelligible; this is a result of our brain being misled through a loss of audibility. Head trauma, neurologic disease, medical disorder or the process of simply aging, can result in alterations in the ability of the brain to process stimuli effectively. This can lead to symptoms that reflect hearing loss; such symptoms may include inattention, inappropriate responses, and confusion.
Hair cells near the wide end of the snail-shaped cochlea detect higher-pitched sounds, such as an infant crying.