THE AUDITORY SENSE

 Danielle Anderson / Emily Breuer  Maxwell Dietrich / Tim Jiang / Linda La 

and Cary Potochnik

A PRESENTATION BY:

Outer EarPinna • Funnels sound waves into

the ear canal • The external flap of skin

and cartilage Ear Canal• The tube through which

sound travels to the eardrum

 Tympanic Membrane• A thin membrane at the

end of the ear canal• Also known as the

eardrumMain Function - Funnel for receiving sounds waves and transporting them inward

http://www.medicalook.com/systems_images/Outer_Ear.jpg

Middle Ear• Air filled cavity behind the

tympanic membrane• Osicles-transmit sound energy

from tympanic membrane to cochlea

    Malleus-attached to               eardrum    Incus    Stapes-attached to     membrane that covers the inside of the oval window• Eustachian tube-opens and

closes to maintain constant pressure with environment

• Main function - To increase the amount of pressure that sounds waves exert upon the inner ear so that transduction can occur http://wikis.lib.ncsu.edu/images/8/85/

Middle_ear.gif

Inner EarOval Window• Beginning of inner earCochlea• Contains fluid-

filled outer ducto duct begins at oval

window, runs to tip of cochlea, ends at another membrane called Round Window

Inner Duct• Sandwiched between

outgoing and incoming portions of outer duct

• fluid filled tube http://images.tutorvista.com/content/nervous-coordination/human-ear-internal-structure.jpeg

Inner Ear Cont.Basilar Membrane•  Forms the floor of Inner Duct•  Where Hair Cells are located

Hair Cells• Receptor cells for hearing• Three outer rows and one

inner row along length of Basilar Membrane

• Cilia protrude from hair cell and abut against Tectorial Membrane

• At other end from its hairs, each hair cell forms synapses with several auditory neurons

 Cilia• Tiny hairs protruding from

each hair cello  move in response to

vibrations from Tympanic Membrane

http://3.bp.blogspot.com/_M2b4HfNGay4/RouytN4RxjI/AAAAAAAAAWI/lntByw74zk8/s320/the_ear_diagram.gif

Basics on wavesVolume = AmplitudePitch = Frequency

http://dbooth.net/mhs/chem/wave-transverse02.gif

Transduction: Turning vibrations into sound

cheriestihler.com/SB/SquishyScience/p-1-3_ani-ear.gifClick to add content

Transduction: The BeginningBefore the phases of transduction, the incoming vibrations are prepared for translation into sound• The Pinna collects sound• The eardrum (tympanic membrane) captures the

sound• The malleus, incus, and stapes  bones receive

vibrations and carry them on to the cochlea• The stapes sends vibrations to the oval window,

which increases the pressure (causing amplification) due to the oval window's small surface area.

Transduction: The CochleaVibrations in the ossicles (malleus, incus, stapes) and the oval window cause changes in the cochlea• The cochlear fluid and the basilar membrane begin

to vibrate according to the input frequencies• Hair cells of the basilar membrane bend against the

tectorial membrane.

http://universe-review.ca/I10-85-cochlea2.jpg

Transduction: The Hair Cells Hair cells strike the tectorial membrane and experience membrane changes, making them more likely to uptake ions and cause an action potential• Lower pitches travel further down the cochlea before

the wave peaks and cause an action potential• The combination of action potentials determines

sound quality• Aural information travels to the higher parts of the

brain, particularly the temporal lobe, for interpretation

Sensorial Hearing Loss

• the bones, eardrum, and membranes of the ear are functional, but the hair cells of the cochlea are damaged

• electrical impulses cannot reach the nerve fibers--> cannot carry information to brain

• can be caused by genetic factors, injury, illness, natural aging, or ototoxic drugs http://www.clivir.com/pictures/hearing_loss/

hearing_types.jpg

Cochlear Implant• transforms sounds into electrical impulses• sends impulses through wires implanted in cochlea• stimulate auditory neuron terminals•  it does not make sounds louder, but instead it

directly stimulates the nerve fibers in the cochlea to help the person sense sound

http://www.terptopics.com/images/ALD%20Cochlear%20Implant%20(External%20Components).jpg

http://kidshealth.org/parent/general/eyes/images_80941/P_cochlear-noConsole.jpg

Synesthesia• Greek for “to perceive together"• "Colored hearing" (chromesthesia) is most common • Results from strong connections between sensory

parts of the brain• Affects about 5% of the population • Consistent with an individual, but varies by person • Dr. Ramachandran on Synesthesia • Part 2 

Chromesthesia• Chromesthesia is a condition

where one 'hears colors.'  For individuals with chromesthesia, certain sounds may trigger visualizations of colors and shapes.

Phantom Words• An auditory illusion that

occurs when the brain tries to process unfamiliar words

• The brain tries to construct phrases because it processes meaningless words

Example 1 Example 2 Example 3 

• Often times the words a person thinks she or he hears are related to what is on the person's mind

BibliographyBogart, Cathy J. "Synesthesia ." Magill's Encyclopedia of Social Science: Psychology. 2nd ed. Pasadena, CA: Salem Press, Inc., 2003. 1599-1602. Print.

Gray, Peter. "Smell, Taste, Pain, Hearing, and Psychophysics". Psychology.  5th ed. New York, NY: Worth Publishers, 2007. 225-261. Print. Magill, Frank N, ed. “The Auditory System.” Psychology Basics. 4th ed. Pasadena, CA: Salem Press, Inc., 1998. 82-87. Print. "Heard and misunderstood: don't believe your ears, says Diana Deutsch." Psychology Today Jan.-Feb. 2004: 83. General OneFile. Web. 23 Oct. 2011.

     

Bibliography(Cont.)Powell, Devin. "What it means to 'feel the noise': hearing, touch appear to be physically linked in the brain." Science News 18 June 2011: 11. General OneFile. Web. 23 Oct. 2011. Ryerson, Nancy. "Technicolor type: shades of synesthesia are built into our brains." Psychology Today May-June 2011: 20. General OneFile. Web. 23 Oct. 2011.

Zeman, A. "Synesthesia--a union of the senses." Journal of Neurology, Neurosurgery and Psychiatry 75.1 (2004): 173+. General OneFile. Web. 23 Oct. 2011.

"Top 10 Incredible Sound Illusions." Top 10 Lists - Listverse. Web. 23 Oct. 2011. <http://listverse.com/2008/02/29/top-10-incredible-sound-illusions/>.