How Does the Ear Detect Sound?

Have you ever wondered how ears detect sound? The human ear is a very delicate and detailed sensory organ. In order to hear sound, the ear must first catch sound waves and direct them into to the hearing part of the ear.

The inner ear senses fluctuations in air pressure and translates them into signals which the brain can understand. But in order to understand this better, let's take a trip with sound as it travels through the ear on its way to the brain and its many receptors.

Sound is a vibration of matter passing through the atmosphere. The human ear receives different vibrations due to the variations of the sound wave frequency. For instance, a higher pitched sound means that "air pressure fluctuation switches back and forth more quickly;" this sound is received as a higher pitch. With fewer fluctuations in air pressure, the sound is captured in a lower pitch. Now let's take a look how the ear catches these sound waves.

The outer ear (the Pinna) works much like a baseball glove, as its shape catches sound waves and transports them through the ear canal to the eardrum. The outer ear is designed to catch sound waves and determine their distance, direction of travel, and pitch frequency. Once these vibrations of sound have reached the eardrum they are intensified by the three smallest bones in the human body.

The eardrum separates the outer ear from the inner ear, and also helps to protect the inner ear from high pitched sounds which may damage its workings. As the sound passes through the eardrum it then travels to the cochlea in the inner ear.

But first these vibrations must be amplified before they can pass through the fluid of the cochlea. Three tiny bones in the ear the: anvil, hammer, and also the stirrup amplify these vibrations. These bones work like a piston as they amplify these vibrations, and push them into the cochlear fluid.

Once the vibrations pass into the inner ear they are "transmitted into nerve impulses the brain can understand." The cochlea is the most complex part of the ear with three adjacent tubes separated by sensitive membranes. One membrane: the basilar membrane is made up of 20 to 30 thousand "reedlike fibers" which extend across its width.

When these tiny fibers are moved, electrical impulses are sent to the cerebral cortex where they can be interpreted by the brain. The brain then determines the strength of the vibrations, the direction of travel, and also the distance of the sound. The brain now works as a super computer registering data, and calculating everything into a conceivable order.

The basic concepts of the ear are quite simple, but certain structures of the ear are still very complex. New advancements in the hearing process are reached every year, but much is still unknown about this tiny part of our body: the ear.

Source of information: www.howstuffworks.com/hearing.htm