5.5 Audition

Question 1

neural pathways of audition

Answer 1

Sounds waves arriving at the outer ear enter the auditory canal. In the canal, the sound waves are amplified, that they travel to the far end of the canal where they hit the tympanic membrane/ eardrum and make it vibrate. These low-pressure vibrations then travel through the air-filled middle ear and rattle three tiny bones: malleus, incus and stapes, which cause the oval window, to vibrate. The oval window is the door to the fluid-filled cochlea. In the cochlea there are tiny haircells located along the inner surface of the basilar membrane. The location of the hair cells on the basilar membrane determines the frequency tuning, the sound frequency that it responds to.

Question 2

tonotopy

Answer 2

The spatial arrangement of the sound receptors is known as tonotopy, and the arrangement of the hair cells along the cochlear canal forms a tonotopic map.

Question 3

Central Auditory System

Answer 3

Once the sound waves are turned into neural signals, they travel through cranial nerve VIII, reaching different anatomical structures where the neural information is further processed. The cochlear nucleus is the first site of neural processing, followed by the superior olivary complex located in the pons, and then processed in the inferior colliculus at the midbrain. The neural information ends up at the relay center of the brain, called the thalamus. The info is then passed to the primary auditory cortex of the brain, situated in the temporal lobe.

Question 4

interaural time

Answer 4

the difference in when a sound reaches each of the two ears

Question 5

two cues to localize sounds

Answer 5

interaural time and the difference in the sound’s intensity at the two ears