HEARING

By: Ellie Erehart, Angie Barco, Maggie Rieger, Tj Myers and

Kameron Thomas

What does hearing do?

Provides you with the ability to locate objects in space

Tell us what we can’t see Audition: the act, sense, or power of

hearing. Something that is heard. Transduction: transformation of one

form of energy into another-especially the transformation of stimulus information into nerve signals by the sense organs.

The Physics of Sound

• On Earth the vibrational energy pushes molecules of the medium back and forth. The changes in pressure spread outward in the form of a sound wave

• In space (no air/medium) = Quiet• Frequency and amplitude are the two

physical properties of any sound wave that determine how it will be sensed by the brain

Frequency: Refers to the number of vibrations (or cycles) the wave completes in a given amount of time

Amplitude: A measure of the physical strength of the sound wave (pressure/energy)

Hertz: the SI unit of frequency, equal to one cycle per second.

Sensing Sounds

1.) Airborne sound waves must be relayed to the inner ear Vibrating waves of air enter the outer ear (Pinna)

strike the ear drum (tympanic membrane) Transmit the vibrations to the hammer, anvil, and

stirrup and they pass the vibrations to the cochlea (inner ear)

Ossicles: the three smallest bones in the body. Located in the middle ear. They transmit sound from the air to the fluid-filled cochlea.

Semicircular Canals: Any of three tubular and looped structures of the inner ear, together functioning in maintenance of the sense of balance in the body.

2.) The cochlea focuses the vibrations on the basilar membrane Airborne waves become “seaborne”

(cochlea is filled with fluid). The stirrup vibrates (wave motion happens) The fluid wave spreads through the

cochlea, causing a sympathetic vibration the basilar membrane

Organ of Corti: a structure in the cochlea of a mammal, consisting of hair cells that serve as receptors for auditory stimuli.

Tectorial Membrane: one of two acellular gels in the cochlea of the inner ear, the other being the basilar membrane. It overlies the sensory inner hair cells and

electrically-motile outer hair cells of the organ of Corti and during acoustic stimulation stimulates the inner hair cells through fluid coupling, and the outer hair cells via direct connection to their tallest stereocilia.

3.) The basilar membrane converts the vibrations into neural messages Swaying of tiny hair cells on the basilar

membrane (like buildings during an earthquake) occurs

They stimulate sensory nerve endings connected to the hair calls and transform the vibrations into neural activity

4.) The neural messages travel to the auditory cortex in the brain Neural signals leave the cochlea in a

bundle of neurons called the auditory nerve

They meet in the brain stem (from both ears) and it ultimately arrives in the auditory cortex

Pitch

A sensory characteristic of sound produced by the frequency of the sound wave

High Frequencies=High Pitch Humans can hear 20 cps (cycles per

second) - 20000 cps. Other animals can hear higher/lower sounds

Place Theory: states that our perception of sound depends on where each component frequency produces vibrations along the basilar membrane

Frequency Theory: states that there are pulses that travel up the auditory nerve, carrying the information about sound to the brain for processing, and that the rate of this pulse matched the frequency of whatever tone you are hearing exactly

Loudness

Is determined by its physical strength (amplitude)

More intense sound waves=louder sounds

Loudness is a psychological sensation

Measured in decibels

Timbre

Complex quality of a sound wave Most natural sound waves are

mixtures Enables you to recognize a friends

voice

Deafness

1.) Conduction: the ways in which sound waves are converted to nerve energy have been interrupted Usually caused by trauma to the middle ear

2.) Sensorineural: hearing loss that occurs from damage to the inner ear, the nerve that runs from the ear to the brain (auditory nerve), or the brain

3.) Nerve: A problem with how the impulses from the oval window are sent to the brain Caused by damage to the auditory nerve or higher

auditory process Most people who are born deaf have this type of

deafness

Cochlear Implant: is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing

Deaf Culture: describes the social beliefs, behaviors, art, literary traditions, history, values, and shared institutions of communities that are affected by deafness

Alikeness to Visual

Different regions of the brain, when activated, produce different sensations