Auditory system class notes pt.2 Flashcards
Each frequency has a different threshold, what is an “Audibility Curve?”
Describes the absolute threshold for hearing each frequency
The dynamic range of intensities from the threshold to pain, is called what?
The auditory response area
Explain what the Equal loudness curve is.
Its how loud a sound at each frequency must be for it to be percieved as equally lound to a reference tone.
What is it called when the same sound seems softer if presented for a long time
Auditory adaptation
What is the name for temporary hearing loss due to high-intensity sounds
Auditory fatigue (more intense than auditory adaptation)
Typically, frequencies at and above the sound are lost (range is 1000-1500hz). So if you loose hearing from exposure at 1000hz, 1000-1500hz will be effected for the person
What is the “Pinna?”
The actual ear on the side of your head.
What is the External Auditory Meatus? What are its functions?
Its the tunnel that leads the outside of the ear to the ear drum. Also called the ear canal.
Functions:
- It funnels sound waves into the ear and amplifies the sounds to make it more clear by using resoannce (boosts sounds in the 2000-5000Hz
- resonance: like blowing across the top of a bottle
- Protects the ear with wax, hairs, and its curved shape
What is the Tympanic Membrane?
The eardrum. The ear drum (tympanic membrane) is struck by sound waves and vibrates, then it transmits the sound to structures in the middle ear
What is the function of the ossicles?
bones connected to the eardrum that trasnfers and amplifies sound vibrations form the air into the fluid filled cochlea
How do the ossicles work together (the steps) and what are the three?
1) Sound waves hit the ear drum, making them vibrate
2) the MALLEUS (which is attached to the ear drum) starts moving
3) the INCUS picks up the motion from the malleus
4) the STAPES passes the vibration into the oval window of the cochlea
This increases the pressure of the sound wave
Why is there a need to increase the pressure of sound waves in the inner ear?
Since the outer and middle ear is willed with air, and the inner ear is filled with fluid, there is a loss of pressure of the sound wave as it trasnfers. The ossicles help compensate for this loss
What equalizes the middle ear pressure with the outside?
The Eustachian tube
What is involved in 3-D balance (vestibular sense)
The semicircular canals
What is the Cochlea?
A snail shaped structure thats filled with cochlear fluid, has different canals
How does the cochlea function?
It turns sound vibrations in the ear into electrical signlas the brain can read. It contains thousands of tiny hair cells that respond to different types of pitches. When fluid moves, it bends the hair cells, the bending creates electrical signals
The cochlea is divided into three canals, explain them.
Scala vestibuli = starts at the oval window, the first canal that gets the fluid moving when sound enters (top)
Scala Media = holds organ of corti and formed by the basilar membrane (middle)
Scala tympani = helps release pressure from the wave (bottom)
What is the Organ of Corti?
The main hearing organ inside of the cochlea that sits on the basilar membrane, that contains 15,000 hair cells
What are Spiral ganglion cells
30,00 nerve fibers that carry sound information from the hair cells in the cochlea to the brain.
95% are type 1 = large inner hair cell
5% are type 2 = outer small cells
