The auditory system Flashcards
Define frequency
Number of compressed or rarefied patches of air that pass by our ears per second (Hertz)
Define intensity/amplitude
Air pressure difference between peaks and troughs, expressed as decibels (dB)
What is the human hearing range?
20-20,000 Hz
What are the ossicles of the middle ear?
Hammer
Anvil
Stirrup
Describe the connection between malleus and incus
Rigid connection
Describe the connection between incus and stapes
Flexible connection
How does the middle ear transfer sounds?
The tympanic membrane is pushed and pulled by compression and rarefraction of the sound waves
What fluid is the scala vestibuli filled with?
Perilymph
What fluid is the scala media filled with?
Endolymph
What fluid is the scala tympani filled with?
Perilymph
What separates the scala media and the scala tympani?
Basilar membrane
Describe the anatomy of the basilar membrane
The basal end is narrower and 100 fold stiffer than the apical end
Describe the inward movement of the tympanic membrane
As the sound wave comes into the ear, the malleus is pulled down and the incus is pulled upwards
- This changes the angle at the incus and stapes join
- Pushes stapes into the oval window
- Fluid is moved along the cochlea
- Pressure is relieved by the round window
What is basal end of the basilar membrane distorted by?
High frequency
What is the apical end of the basilar membrane distorted by?
Low frequency
