1b Auditory Systems Flashcards
What does a vestibular organ capture?
Captures low frequency motion (movements)
What does a hearing organ capture?
Captures high frequency motion (sound)
What is meant by the frequency of a sound?
The number of cycles of the sound per second, perceived tone
What is the frequency measured in?
Hertz
What is the amplitude?
the sound pressure - therefore corresponding to loudness
What is the human range of hearing?
20-20000 Hz
0-120 decibels
What are the functions of the outer ear?
Capture sound and focus it onto the tympanic membrane
Modest amplification of the upper range of speech frequencies by resonance in the canal
To protect the ear from external threats
By how much does the outer ear amplify the sound?
10 DB
What is the middle ear?
All the structures from the tympanic membrane to the oval window
What is the main function of the middle ear?
Mechanical amplification (Provides an additional 20-30DB)
What happens to the tympanic membrane when a sound hits it?
It vibrates at the same frequency as the sound wave which just hit it
What are the ossicles?
The three smallest bones in the body -
Malleus
Incus
Stapes
What is the inner ear called?
Cochlea
What is the function of the cochlea?
function is to transduce vibration into nervous impulses
What two things does the cochlea capture?
Captures the pitch and intensity of the sound
Where does the stapes connect to the cochlea?
The oval window
Where does the sound go from the oval window of the cochlea?
Scala Vestibuli
What does the scala vestibuli and the scala tympani contain?
Perilymph
What does the scala media contain?
Endolymph
What is the perilymph high in?
Sodium
What is the endolymph high in?
Potassium
Where is the hearing organ or Organ of Corti Located?
In the basilar membrane - separates the scala media and the scala tympani
What type of structures are the scala vestibuli and the scala tymphani?
Bone structures
What type of structure is the scala media?
Membranous Structure
Which sound frequency moves the base of the basilar membrane?
high frequency sounds
Which sound frequency moves the apex of the basilar membrane of the cochlea?
Apex - Wide and loose
Moved by lower frequency (Hz) sounds
How is the basilar membrane arranged?
Tonotopically - same principle as the xylophone
What are the two types of hair cells which the organ of corti contains?
Inner hair cells
Outer hair cells