Audition Flashcards
What are some important functions for hearing
- Communication
- Detect danger
- Help
What is sound
Variations in air pressure
What is the difference between the speed of sound through air vs. through water
air 767mph (340m/s)
water 1500m/s
What is a sounds wave
Alternating peeks and valleys of compressed air
What are the variables in sound?
Frequency (pitch)
Intensity (loudness)
What is the definition of frequency
The number of comprised air patches (Hertz)
-number of cycles/second
What is the definition of Intensity
The difference in pressure between compressed air patches
-amplitude
What is the human frequency range
20-20,000
In which frequency range are we most sensitive to
2,000-4,000
which is speech range
What is the difference between Hertz and Decibel
Hertz measured the pitch
Decible measures the loudness
What is the minimum audibility curve
The minimum frequencies that are at a level for us to hear
What are the 3 major divisions of the ear
- Outer Ear
- Auricle (Pinna)
- Auditory canal - Middle Ear
- Tympanic membrane
- Ossicles - Inner Ear
- Oval window
- Cochlea
What is the function of the auditory canal
To protect the ear drum
Enhances the intensities of sound by resonance
What is the definition of resonance
A mechanism that enhances the intensity of certain frequencies because of the reflection of sound waves in a closed tube
-amplifies frequency depending on length and width of tube
What are the 3 Ossicles
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
What is the Eustachian (auditory) tube
An airway between the middle ear and the pharynx
-allows you to change the pressure in your ear
What are the 3 reasons why the Ossicles necessary
- Sound vibration is ineffective at moving fluid
- Ossicles amplify the force exerted against the oval window
- Ossicles convert air pressure changes to mechanical changes (causing fluid changes win the cochlea)
What are the two windows of the cochlea
The oval window (in contact with stapes)
Round window
What are the 3 ducts of the cochlea
- Vestibular duct (separated by resigners membrane)
- Cochlear duct (separated by basilar membrane)
- Tympanic duct
What are the 2 different fluids in the 3 chambers
- Perilymph (Vestibular and tympanic duct, flows into each other)
- Endolymph (Cochlear duct)
Why is the basilar membrane important?
Contains the Organ of Croti
What hangs over the organ of corti
The tectoral membrane
What is the Helicotrema
A hole between the scala vestibule and scala tympani
at the very end of the unrolled cochlea
How does sound move through the cochlea
Oval window> Scala Vestibuli> Helicotrema> Scala Tympani> Round Window
What is the base of the basilar membrane
The base is thin and the membrane is thick
-high frequencies are encoded
What is the apex of the basilar membrane
The apex is wide and the membrane is less rigid
-low frequencies are encoded
What is the organ of corti
Lies on the basilar membrane and contains hair cells
The movement of the hair cess changes the activity of the hair cell
What is the hair cell
Cells in the organ of corti in which when moved, the hair cells depolarize when the stereocilia bend
Tips of the stereocilia are in contact with the sectoral membrane.
What are the 2 types of hair cells
Inner hair cells
Outer hair cells
What are inner hair cells
Auditory receptor cells in the inner ear that are primarily responsible for auditory transduction and the perception of pitch
-only 5000 per ear
What are outer hair cells
Auditory receptor cells in the inner ear that amplify the response of the inner hair cells
-more numerous
What is motile response and how does it work
A response to sound of the outer hair cells in which the cells move
Cells tilt and get slightly longer, amplifies the basilar membrane vibration and amplify the response of the inner air cells
How do signals get out of the cochlea
Hair cells synapse with spiral ganglion cells
-the axons of these neurons form the auditory portion of the Vestibulocochlear Nerve (cranial nerve 8)
In which place in the brain does the sound from both ears come together
The Superior olives
Where is the primary auditory cortex
On the superior temporal gyrus
What kind of map is in the auditory cortex
Tonotopic map
-based on frequency lengths, shortest in the front and longer towards the back
Why doesn’t the destruction of the auditory cortex in one hemisphere result in loss of hearing on one side
Because input from both ears goes to each hemisphere
What does the destruction of the auditory cortex result in
A loss of the ability to localize sound in the opposite hemifield
What is most hearing loss due to
Death or destruction of hair cells
-cant regenerate
