a
Anatomy of the Outer Ear
pinna and external ear canal
Longer ear canal=________ resonant frequency
Lower
Middle Ear Anatomy
- Tympanic membrane (ear drum)
- Auditory Ossicles
- 2 Middle Ear muscles
- Eustachian tube
What are the three auditory ossicles?
Malleus, Incus, Stapes
What are the two middle ear muscles?
tensor tympani and stapedius
Functions of the Outer Ear
Pinna collects and localizes sound
Outer Ear canal amplifies sound
Outer Ear Sound Pressure Gain is
2.5 kHz because that is the resonant frequency
Functions of the Middle Ear
-Amplify the sound
-Protection from loud sounds: Acoustics reflections help reduce sound transmission
-Overcome acoustic impedance mismatch problem
What do the Stapedius and Tensor Tympani do?
Protect the inner ear from loud sound
_______ Acoustic Impedance=More difficult for sound to travel
Higher
Functions of Inner Ear
hearing and balance
Anatomy of Inner Ear
cochlea and vestibule
What happens when the vibration of a sound wave transfers from TM in the air to fluid-filled cochlea?
Sound travels in the air first and then the fluid in the middle ear causing energy loss (because of acoustic impedance)
Acoustic Impedance
total opposition against sound propagation
What are the 3 mechanisms for the impedance mismatch problem?
Area Ratio, Lever System, Buckling of Tympanic Membrane
Helicotrema
joint opening at the apex of the cochlea for scala vestibuli and tympani
Stereocilia is found where?
Organ of Corti
Healthy OHC= ____ tuning curve
sharp
response of basilar membrane to sound
Traveling wave of the basilar membrane: displacement of BM caused by the flow of perilymph in the scala vestibuli and scala tympani
What are the three Scalae?
1. Scala vestibuli
2. Scala media or cochlear duct
3. Scla Tympani
Temporal Integration
the process by which a sound at a constant level is perceived as being louder when it is of greater duration, OR the ability of the auditory system to add up information over time or over duration up to a critical duration so that the auditory system to assimilate sound energy over time
Characteristic Frequency
when a hair cell is triggered by a specific frequency (favorite frequency) that is the highest threshold for it to be stimulated and trigger the Basilar Membrane
What do HSC do?
-HSC sits on the Basilar Membrane, which is why the Basilar Membrane moving up and down is significant
-When HSC get stimulated (move up and down), they convert vibration to neural impulses which go to auditory nerves
Function of the Cochlea
convert physical vibration to neural pulses/signals (hearing sensory cells do this and send to auditory nerves)
Where is the organ of corti located?
scala media