Auditory System Jackson, Kaitlynn Miranda, Fermin

A. Outer Ear Pinna- the pinna refers to the visible part of the ear, outside of the head. It is made of cartilage covered by skin. The function of the pinna is to capture any sound waves and lead it towards the inner ear. It also helps determine where sound is coming from. Ear Canal- (external auditory meatus) the purpose of the ear canal is to direct sound to the more sensitive part of the outer ear; the tympanic membrane. Tympanic Membrane- is a cone-shaped membrane between the external ear and the middle ear.

B. Middle Ear 1.The primary purpose of the middle ear is so that when sound waves move through this area, it can be transferred into fluid so it can move through the cochlea: Three bones known as the anvil (incus), hammer (malleus), and stirrup (stapes) act as a lever system. Once the tympanic membrane senses sound, it vibrates letting the middle ear get into motion. 2. The hammer is connected to the tympanic membrane, and collects larger sound which is also connected to the anvil in a hinged shaped structure. 3.The stirrup is fused with the anvil and acts as one bone. The stirrup transmits sound vibrations from the incus.

C. Inner Ear Cochlea- the cochlea contains nerve endings needed to convert sound patterns into electrochemical pulses to the brain. The vestibular system gives animals a sense of balance. Semicircular canals-three fluid-filled loops with tiny hairs covering each canal. When head is tilted, the fluid moves which cause the hairs to translate movement to the nerves that send messages to the brain.

C. Inner Ear (Cochlea Function) After sound passes through the middle ear, sound waves are transferred into the oval window that connects to the cochlea. As the fluid (the sound) moves through the cochlea, hair cells are set in motion converting the fluid into electrical signals so that nerve cells can be translated by the auditory cortex for further processing.

D. Brain Processing Once sound has been released from the cochlea, into the cochlear nerve to the brain, brain neurons in the auditory cortex translate sound From here, sound is sent to the brain, nervous system, and spinal cord.

E. Deafness 1.Deafness- is the state of somewhat or completely lacking the ability to hear. Deafness can be caused by many different factors, including age, heredity, noise, and physical trauma. Age- Presbycusis, also known as age-related hearing loss is common and begins in adulthood, but does not become a problem until much later on. Heredity- Deafness can be inherited, and both dominant and recessive genes exist where hearing impairment is found. Noise- Noise is the cause for half of all the instances for deafness. Although we experience sound everyday, we may be taking in a unsafe amount of noise levels.

E. Deafness Cont. Physical Trauma- Anyone who has suffered brain, or head damage may have temporary or permanent hearing loss, depending how badly the auditory cortex was injured. The auditory cortex is a vital piece in processing the sound so any damage to the cortex is fatal. Several parts of the ear may be damaged when someone is deaf since most parts share the role of sending sound to the brain. The parts of the ear that can be damaged and affect hearing are the following: the auditory nerve, the cochlea, the eardrum, and the middle ear ossicles.

Bibliography InteractiveBiology. “037 How Sound is Transferred to the Inner Ear.” Youtube. Web. 2o Feb How do the hammer, anvil and stirrup bones amplify sound into the inner ear?. Douglas E. Vetter. 31 Jan Johnson, George, and Peter Raven. Biology. Austin: Holt, Rinehart and Winston, 2007 Semicircular Canals. Kids Health Hear. Kriten Hayes. 13 April 2009