Auditory System

Question 1

What affects pitch?

Answer 1

Frequency of wavelengths–> more wavelengths means a higher pitch

Question 2

What affects intensity?

Answer 2

Loudness of the sound, or the amplitude of the wavelength

Question 3

What is timbre?

Answer 3

Quality, depends on overtones–>pitch and frequency do not change

Question 4

What is the purpose of the outer ear, middle ear, and inner ear?

Answer 4

External ear focuses the sound, middle ear passes on/amplifies vibrations to the inner ear (?) and the inner turns sound into an action potential to be perceived by the brain

Question 5

Briefly describe how the ear works to send signals to the brain

Answer 5

The pinna focuses the sound, the middle ear auditory ossicles transduce the sound to the inner ear, where vibrations in the fluid of the inner ear cause vibrations in the basilar membrane. This causes vibrations in the organ of corti containing hair cells; the hairs bend, which released an action potential in affert neurons leading to the brain from the inner ear. The axons of the nerves are bundled together to create the auditory nerve, which is a cranial nerve leading to the thalamus

Question 6

What are the three cavities of the cochlea?

Answer 6

Scala tympani, scala media, and scala vestibuli

Question 7

What are the scala tympani and scala media filled with?

Answer 7

Scala tympani: filled with perilymph, which is an ECF with an ionic composition similar to plasma and rich in sodium.
Scala media: Filled with endolymph, which is an ECF where potassium is the depolarization electrical current (in the hair cells) and NOT sodium

Question 8

What is the function of the outer hair cell in the Organ of Corti? The Inner hair cell?

Answer 8

Outer hair cell amplify the vibrations from the basilar membrane; inner hair cells convert the sound vibrations into a nerve signal

Question 9

What is the purpose of the oval window?

Answer 9

To send pressure waves through cochlea

Question 10

Where do high frequency sounds best vibrate in the cochlea?

Answer 10

The narrow stiff end of the basilar membrane, near the oval window

Question 11

Where do low frequency sounds best vibrate in the cochlea?

Answer 11

The flexible, wide end of the basilar membrane near the helicotrema (where the scala tympani and vestibuli meet)