Auditory System

Question 1

Amplitude

Answer 1

Height of sound wave
- Corresponds to volume of sound
- Stronger vibrations = Larger changes in pressure = Higher volume

Question 2

Frequency

Answer 2

Number of sound waves in given period
- Corresponds to pitch
- Greater frequency shrinks wavelength = high pitch

Question 3

Outer Ear

Answer 3

Funnels sound waves into ear canal
1. Pinna

Question 4

Middle Ear

Answer 4

Concentrates sound energies
1. Tympanic Membrane (Eardrum)
2. Ossicles
3. Oval Window
4. Round Window

Question 5

Inner Ear

Answer 5

Converts sound into neural activity
1. Cochlea
- Scala vestibuli
- Scala media
- Scala tympani

Question 6

Scala Media

Answer 6

Middle Canal of Cochlea
- Contains Organ of Corti
-

Question 7

Tectorial Membrane

Answer 7

1. Connects to vestibular canal
2. Stereocilia protude from each hair cell & extend into membrane

Question 8

Basilar Membrane

Answer 8

1. Hair cells embedded into membrane
2. Anchors auditory system to tympanic canal
   - Higher frequencies displace base
   - Lower frequencies displace apex

Question 9

Vestibulocochlear Nerve

Answer 9

Cranial nerve that innervates inner ear
1. Hearing & sensation of balance

Question 10

Inner v. Outer Hair Cells

Answer 10

Outer: Discriminates frequencies
- Expansion: stiffen & reduce vibration
- Contraction: relax & increase vibration
Inner: Perception of sound

Question 11

Auditory Pathway

Answer 11

1. Cochlear Nucleus
2. Superior Olivary Nucleus
3. Inferior Colliculus
4. Medial Geniculate Nucleus (Thalamus)
5. Temporal Lobe

Question 12

Tonotopic Mapping

Answer 12

1. Arrangement according to frequencies at which they respond
2. Row of neurons respond to specific range of frequencies
   - Apex: low frequencies
   - Base: high frequencies

Question 13

Vestibular System

Answer 13

1. Detects position and movement of the head
2. Three axes
   - Pitch
   - Yaw
   - Roll
3. Mechanically-gated ion channel system
   - Hair cells sway - perceives movement on three axes

Question 14

Binaural Cues

Answer 14

1. Intensity & Latency Differences
   - Takes longer for sound waves to reach one ear than the other
2. Signal sound location

Question 15

Streams of Information

Answer 15

1. Dorsal: Where?
   - parietal lobe
2. Ventral: What?
   - temporal lobe

Question 16

Auditory Stimuli to Neural Activity

Answer 16

1. Vibration causes tip-links to sway
2. Tip-links slant & rip open mechanically-gated ion channel
3. Influx of K+ and Na+
4. Hair cell depolarizes
5. Opens voltage-gated Ca2+ channel
6. Neurotransmitter release
7. Action potential