Along with vision, hearing is one of the most important senses that humans have. We use it to communicate, learn, and stay aware of our environment. In fact, hearing is the only sense that never stops receiving sensory input. While all of our other senses become drastically less sensitive when we are sleeping, our brain still processes auditory information to awaken us the second something is wrong. Although this may have been more practically used before people slept safely in homes, it’s still useful for hearing a fire alarm or our alarm clock in the morning. We are able to hear by processing sound waves. This energy travels through the delicate structures in our ears to be transformed into neural activity so that we can perceive the sensory information we receive (Myers, 2010).
Each of the senses receives a different stimulus that allows us to perceive that specific type of information. For hearing the stimulus is sound waves. These are waves of pressure that are conducted through a medium (Martini, 2009). Often this medium is air but it can also be water or a solid object. Each wave consists of a region where the air molecules are gathered together and an opposite region where they are farther apart (Martini, 2009). A wavelength is the distance between either two wave peaks or two wave troughs. The number of waves that pass through a fixed reference point in a given time is the frequency. High pitch sounds have a high frequency where as low pitch sounds have a low frequency (Myers, 2010). The amplitude is the amount of energy, or intensity, in a sound wave. The more energy that a sound wave has, the louder it seems. For us to perceive any of the sound waves around us, they must pass through the external, middle, and inner ear.
Sound waves first enter the outer ear and travel down the auditory canal. The canal ends at the eardrum, a thin, semitransparent membrane (Martini, 2009). The eardrum extends across the entire canal and provides a surface where the sound waves can collect. This is where the outer ear ends and the middle ear begins. The middle ear contains three tiny bones, or auditory ossicles, the malleus, the incus, and the stapes. The malleus is attached to the eardrum, the incus is attached to the malleus, and the stapes is attached to the incus. The stapes is also bound to the oval window, an opening in the bone that surrounds the inner ear (Martini, 2009). As the sound waves vibrate the eardrum, the auditory ossicles change the sound waves into mechanical movements. They collect the force applied to the eardrum and, functioning as a lever system, focus this on the oval window (Martini, 2009).
The inner ear is an interconnected network of fluid-filled tubes encased in bone. One part of this network called the cochlea, a spiral shaped bony chamber, contains the receptors that provide our sense of hearing. Because the fluid is...