Hearing By: Hima Veeramachaneni

Jenna WorlundEfraim Arcaya

Lea FinderBecca Liu

Transduction • Transform physical energy into the form of neural

messages• Order

– Beings with detection by a sensory neuron of the physical stimulus.– When the appropriate stimulus reaches a sense organ it activates

specialized nerve signals, called receptors– Information signal travels from the receptor cells along a sensory

pathway– From neural impulses arriving from the pathways, the brain then

extracts information about the basic qualities of the stimulus, pitch and direction.

• The only thing that continues on into the nervous system is information carried by the neural impulse

• Sensory Receptors– Transforms stimulus information into electrochemical signals

Audition

• Act of hearing or the scientific name for the perception of sound (commonly known as hearing)

• Sound is a form of energy that moves through air, water, and other matter, in waves of pressure.

• Two properties of sound wave:

• Frequency- the number of cycles completed by a wave in a given amount of time.

• Amplitude- The physical strength of a wave. This is usually measured top to bottom on a graph of the wave.

Pitch

• A sensory characteristic of sound produce by the frequency of the sound wave

– High Frequency = High Pitch

– Low Frequency = Low Pitch

Unit of measurement

• Hertz (Hz)– Unit of frequency– Humans generally

hear sounds with frequencies between 20 Hz to 20 KiloHertz(kHz)

• Decibel (dB)– A logarithmic unit that

indicates the ratio of a physical quantity relative to a specified or implied reference level.

– A measure of a sound pressure level

Major Components

Cochlea

• A hollow tube in the inner ear of higher vertebrates

• Usually coiled like a snail shell

• Contains the sensory organ of hearing (Organ of Corti)

http://www.marshfieldclinic.org/patients/?page=ent_ear_cochlea

Organ of Corti• Located within the cochlea

• Contains receptors that responds to sound waves

• Highly specialized structures that respond to fluid-borne

vibrations

• Transduces pressure waves to action potentials.

Ossicles

• Smallest bones in the human body

• Malleus• Incus• Stapes• Contained in the middle ear

space• Trasmit sound from the air to

the fluid-filled labyrinth• absence of the auditory

ossicles would constitute a moderate-to-severe hearing loss.

http://www.web-books.com/eLibrary/Medicine/Physiology/Skeletal/Divisions.htm

Oval Window

• Located on the Medial Wall of the tympanic cavity, leading into the vestibule, to which the base of the stapes is connected.

• The ossicles of the ear transmit the sounds vibrations to the cochlea

http://www.daviddarling.info/encyclopedia/O/oval_window.html

Tectorial Membrane

http://www.moleshare.org.uk/resources.asp?k=organ&z=0

The membrane with a jelly like consistency that covers the Organ of Corti.

Basilar Membrane

• A thin strip of tissue sensitive to vibrations in the cochlea

• Contains hair cells connected to neurons

• When a sound wave causes the hair cells to vibrate, the associated neurons become excited

• As a result, the sound waves are converted into nerve activity.

http://www.cs.indiana.edu/~port/teach/641/hearing.for.linguists.html

Theories

Place Theory:

- Different places on the basilar membrane send neural codes for different pitches to the auditory cortex of the brain.- Sound waves passes through inner ear, the basilar membrane vibrates.- Then different frequencies activate different locations on the membrane

Frequency Theory:

- Neurons on basilar membrane respond with different firing rates for different frequencies.- The basilar membrane deals with frequencies below about 5000Hz.

Hearing and The Brain

• Auditory nerve takes sound information from the cochlea to the thalamus

– Thalamus- part of the brain that relays sensory information to the rest of the brain

• Thalamus sends the information to the temporal lobe for higher processing

– Temporal lobe- cortical lobe that processes sounds including speech

The Hearing Process

http://www.dizziness-and-balance.com/disorders/hearing/

hearing.html

Hearing Disorders

Conduction Deafness•  Hearing loss or

impairment resulting from interference with the transmission of sound waves to the organ of Corti called also conductive deafness transmission deafness.

• Too loud of musichttp://www.clivir.com/lessons/show/conductive-hearing-loss-causes-symptoms-and-treatments.html

Conduction Deafness

• Hearing loss or impairment resulting from interference with the transmission of sound waves to the organ of Corti

• also conductive transmission deafness

• Too loud of music

http://www.clivir.com/lessons/show/conductive-hearing-loss-causes-symptoms-and-treatments.html

Sensorineural deafness

• Hearing loss or impairment due to a lesion or defect of the cochlea or the acoustic nerve.

http://www.clivir.com/lessons/show/sensorineural-hearing-loss-causes-symptoms-and-treatments.html

Sensorineural Deafness

Hearing loss or impairment due to a lesion or defect of the cochlea or the acoustic nerve.

http://www.clivir.com/lessons/show/sensorineural-hearing-loss-causes-symptoms-and-treatments.html

Central Deafness

• The loss or impairment of hearing caused by disease or a defect in the auditory system of the brain.

Central Deafness

The loss or impairment of

hearing caused by disease or a defect

in the auditory system of the brain.

Cochlear Implant

• “Artificial ear”• a device consisting of

microelectrodes that deliver electrical stimuli directly to the auditory nerve when surgically implanted into the cochlea, enabling a person with sensorineural deafness to hear.

http://www.childrensspecialists.com/body.cfm?id=838

Cochlear Implant• “Artificial ear”• A device consisting of

microelectrodes that deliver electrical stimuli directly to the auditory nerve

• Surgically implanted into the cochlea

• Enables a person with sensorineural deafness to hear

http://www.childrensspecialists.com/body.cfm?id=838

Deaf Culture

The social beliefs, behaviors, art, literary traditions, history, values, and shared

institutions of deaf people that use sign language.

• Freedman, Nelson, Kevin Jordan, Michael W. Levine, and John Pittenger. "Chapter 4, Sense and Perseption." Psychology Themes and Variations. By Stephen Blessing. Eighth ed. Belmont, CA: Linda Schreiber, 2010. 129-83. Print.

Hain, M.D., Timothy D. "Hearing Loss." Otoneurology Index. 25 Oct. 2010. Web. 14 Nov. 2010. <http://www.dizziness-and-balance.com/disorders/hearing/hearing.html>.

Hicks, Barb. "Conductive Hearing Loss Causes, Symptoms And Treatments - Clivir - How to Lessons, Tips & Tutorials." A Learning Community - Clivir - How to Lessons, Tips & Tutorials. 13 July 2009. Web. 14 Nov. 2010. <http://www.clivir.com/lessons/show/conductive-hearing- loss-causes-symptoms-and- treatments.html>. Johnson, Robert, Ann L. Weber, and Craig W. Gruber. "Sensation and Perception." Psychology

AP Edition. By Phil Zimbardo. AP ed. Philip G. Zimbardo, 2007. 109-54. Print.

Citations