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Transcript of Hearing
which is very flexible. (Grey 2011) Some experts on human hearing are concerned that the regular use of portable mp3 players, which can play music at sound pressure levels of more than 100 decibels through their stock earbuds, may cause partial deafness in many young people today as they grow older.
(Grey 2011) The ability to detect the direction of a sound source contributes greatly to the usefulness of hearing. When startled by an unexpected rustling, we reflexively turn toward it to see what might be causing the disturbance.
(Grey 2011) You were probably able to figure out that your ears help you to hear sounds, but what you probably did not know is that your ears also help you to keep your balance.
How You Hear
When an object makes a noise, it sends vibrations (better known as sound waves) speeding through the air. These vibrations are then funneled into your ear canal by your outer ear. As the vibrations move into your middle ear, they hit your eardrum and cause it to vibrate as well. This sets off a chain reaction of vibrations. Your eardrum, which is smaller and thinner than the nail on your pinky finger, vibrates the three smallest bones in your body: first, the hammer, then the anvil, and finally, the stirrup. The stirrup passes the vibrations into a coiled tube in the inner ear called the cochlea. The human ear can detect pitch changes as small as 3 hundredths of one percent of the original frequency in some frequency ranges. Some people have "perfect pitch", which is the ability to map a tone precisely on the musical scale without reference to an external standard. The ear is the organ of hearing. The outer ear protrudes away from the head and is shaped like a cup to direct sounds toward the tympanic membrane, which transmits vibrations to the inner ear through a series of small bones in the middle ear called the malleus, incus and stapes. The inner ear, or cochlea, is a spiral-shaped chamber covered internally by nerve fibers that react to the vibrations and transmit impulses to the brain via the auditory nerve. The brain combines the input of our two ears to determine the direction and distance of sounds.
The inner ear has a vestibular system formed by three semicircular canals that are approximately at right angles to each other and which are responsible for the sense of balance and spatial orientation. The inner ear has chambers filled with a viscous fluid and small particles (otoliths) containing calcium carbonate. The movement of these particles over small hair cells in the inner ear sends signals to the brain that are interpreted as motion and acceleration. Sound detection, hearing allowance, and balance maintenance are the main functions of the ear. To hear, the ear must respond to mechanical stimulation by sound waves. The brain then interprets the information as a specific sound. Maria Lepak, Hour 1. The Sense of Hearing In a more detailed sense; the hair cells located in the organ of Corti transduce mechanical sound vibrations into nerve impulses. They are stimulated when the basilar membrane, on which the organ of Corti rests, vibrates.
The hair cells are held in place by the reticular lamina, a rigid structure supported by the pillar cells, or rods of Corti, which are attached to the basilar fibres. At the base of the hair cells is a network of cochlear nerve endings, which lead to the spiral ganglion of Corti in the modiolus of the cochlea. The Auditory Canal is the path made of cartilage and bone between the eardrum and the opening of the ear. Sound waves must travel down this canal to reach the inner ear and be translated into a signal for the brain to receive. AUDITORY CANAL: The Tympanic Membrane also known as the eardrum is the membrane that translates incoming sound waves from the Auditory Canal into vibrations that move the ear ossicles in the middle ear. TYMPANIC MEMBRANE: The Ear Ossicles include the Malleus, Incus, and Stapes better known as the hammer, anvil, and stirrup due to their shapes. These small auditory bones are displaced by vibrations of thetympanic membrane. Consequently, the Ossicles amplify and transfer the vibrations into the inner ear.Muscles at the Malleus and Stapes pull the two bones away from the membranes they are attached to in order to prevent them from rupturing their respective membranes. EAR OSSICLES: OVAL WINDOW: The Oval Window vibrates in response to the movement of the Ear Ossicles, transferring the sound wave into the Cochlea. The Cochlea is the coiled structure within the inner ear that is filled with fluid.Within the Cochlea is an inner channel referred to as the Cochlear Duct. The Basilar Membrane separates these channels, and can vibrate in response to thesound waves travelling through the Cochlea. Within the Cochlear Duct are hair cells that bend in response to the displacement of the Basilar Membrane,resulting in the release of neurotransmitters. COCHLEA: The Auditory Nerve conducts nerve impulses to the brain in response to stimulation by neurotransmitters. The auditory nerve is situated behind the cochlea, where it can easily sense the presence of neurotransmitters released due to the hair cells. AUDITORY NERVE: The Round Window is a membrane connected the Cochlea just below the Oval Window. This membrane’s purpose is to dissipate the sound wave traveling through the Cochlea once the sound wave has stimulated the Auditory Nerve. ROUND WINDOW: This physiological section describes the electric response of the organ of Corti, as observed by external electrodes, and also the whole-nerve action potential. Adequate instrumentation for the study of single sensory units was not yet available, but we were able to make some first-order comparisons of neurophysiologica activity with psychoacoustic data and to venture some guesses concerning the neural code of the auditory system. Much of this section is now chiefly of historical interest. The speculations concerning the cochlear mechanics and neural excitation are woefully out of date. We did not then appreciate the significance of von Bekesy's traveling wave concept. Research into hearing and communication is providing a scientific foundation for understanding the anatomy, physiology, and genetics of the hearing pathway, as well as the social and cultural aspects of human communication. The following discussion is designed to introduce you to some major concepts about hearing and communication. An activity that can be performed to understand the sense is that each individual in the class pairs up with another person and one of the individuals wears a blindfold and faces any random direction. Then the other partner goes somewhere (anywhere!) in the room and makes a noticeably loud noise and the person wearing the blindfold has to turn and point to wherever the noise came from. To answer the question, "Why did this happen to my child?" there could be at least one of three answers.
Unknown (the cause of the hearing loss cannot be discovered)
Non-genetic (illness or trauma before, during or after birth)
Genetic (the hearing loss will depend on the type of inheritance present)
In 70% of cases of genetic hearing loss, the cause is autosomal recessive Subtopics:
Educating the deaf, deafness in general around the world, and the diversity of deafness in the community. A more complicated activity found on - http://faculty.washington.edu/chudler.neurok.html
You hear the ringing of the phone in the middle of the night, but you just can't find it. You can hear it, but you can't see it. Where is that thing? Just how good is the ability to find things using only the sense of hearing. Blindfold a person. Have him cover one ear. Take a watch or stopwatch that "ticks". An electric watch will not work. Ask the student to tell you when he hears some "ticking". Approach the blindfolded person from several different angles and record the distance when the subject says "I can hear the ticking". Keep track of the angles and the distances. Repeat the same experiment with the student's other ear closed. Then do it again with both of his ears opened. Works Cited:
Oracle ThinkQuest Education Foundation. (1998). Your Sense of Hearing. Retrieved from http://library.thinkquest.org/3750/hear/hear.html
Zamora, Antonio. (2012). Anatomy and Structure of Human Sense Organs. Retrieved from http://www.scientificpsychic.com/workbook/chapter2.htm
Ear Nose Throat Information Magazine. (2005). What is the Ear and how does the Ear work? Retrieved from http://www.entmags.org/ears.asp
John Wiley & Sons, Inc. (2012). The Five Sense Organs in Human Beings. Retrieved from http://www.dummies.com/how-to/content/the-five-sense-organs-in-human-beings.html
Scribd Inc. (2012). Sound Transduction in the Ear. Retrieved from http://www.scribd.com/doc/29458274/Sound-Transduction-Ear
S. Smith Stevens and Hallowell Davis. (1938; Reprinted in 1983). Hearing, Its Psychology and Physiology. Retrieved from http://scholar.google.com/scholar_url?hl=en&q=http://www.abdi-ecommerce10.com/asa/images/product/medium/0-88318-4265.pdf&sa=X&scisig=AAGBfm0kdrTvgsXbZCLNy0cg-sHQm6649Q&oi=scholarr
Neuroscience for Kids. (2011). Our Sense of Hearing. Retrieved from http://faculty.washington.edu/chudler/pdf/hearsg.pdf
Boys Town National Research Hospital. Causes of Hearing Loss
Answers to some frequently asked questions. Retrieved from http://www.babyhearing.org/hearingamplification/causes/faqs.asp
http://faculty.washington.edu/chudler/chhearing.html (on project guideline sheet)
Angeli, E., Wagner, J., Lawrick, E., Moore, K., Anderson, M., Soderlund, L., & Brizee, A. (2010, May 5). General format. Retrieved from http://owl.english.purdue.edu/owl/resource/560/01/