Physics of the Ear
The ear is an extraordinary human organ that many people take for granted until it doesn’t function. It is the only device that allows the human to hear sounds in their environment. The ear is made up of many parts that distinguish various sounds through different means. The ear anatomy and physiology along with how sound waves are transmitted into meaningful sounds will help one understand how hearing loss occurs.
The ear is made up of three areas: the outer, middle, and inner ear. The outer ear is very important for collecting sound waves. It is made up of the pinna and the ear canal. The pinna, the actual physical outward appearance of the ear, receives sound ...view middle of the document...
Basically how sound travels through the ear is a process of many steps. The sound waves are gathered by the pinna and then funneled into the meatus. Those waves then begin to vibrate the tympanic membrane which in turn hits against the malleus. The ossicle bones then vibrate like a chain reaction. The footplate will hit the oval window which triggers the fluid in the cochlea to move. The movement sways across the different hair cells creating impulses that are sent to the brain through the eighth cranial nerve.
The interesting question is how waves can become meaningful sounds. First off we must know that sound is a wave. It is impossible for sound to be a particle or atom because if it was a particle the two different sounds would eventually collide and if sound was an atom one sound would deflect another and neither one of these situations ever happens. A characteristic of sound is that different sounds pass through one another, for example, a sound and its echo. Therefore, it is safe to conclude that sound is a form of wave. Sound is molecules vibrating back and forth creating what we call a longitudinal wave. However, very few times do we consider sound as flow of power yet that is exactly what it is. It is a power that flows through the air steadily. The speed at which it travels depends on the temperature and the particular gas that it is traveling through. However, the speed of sound at room temperature in Oxygen is 343 meters per second. The longer the wavelength the less frequency occurs; the shorter the wavelength the higher the frequency.
Now that we know that sound is a wave and the speed of sound it is possible to find the frequency, which is what determines the pitch that one hears with the equation speed = wavelength x frequency. Frequency is the amount of cycles per second. The human being uses frequency to determine the difference between tones. People
interpret the number of cycles brushing the hairs per second to retrieve the pitch. There are two different theories explaining the frequency discrimination: the ‘place theory’ and the ‘temporal’ or ‘frequency’ theory. The ‘place theory’ states that the subject will become aware of the specific places where the maximum of excitation in the cochlea occur. The ‘frequency’ theory states that the subject will determine the difference between the two tones according to the time intervals between neural firings. Rutherford believes that each hair cell responds to every tone and that frequency information was carried through frequency nerve impulses. There are arguments both for and against both of these theories. One way to envision what is happening is to picture a grain field on a mildly windy day; how the wind sweeps across the grain. The wind is the fluid sweeping across these particular hair cells creating a stimulus that creates the frequency otherwise known as the pitch. Along with pitch the ear interprets the direction of the sound source.
Sounds surround the...