Auditory System Flashcards
Amplitude
Height of sound wave
- Corresponds to volume of sound
- Stronger vibrations = Larger changes in pressure = Higher volume
Frequency
Number of sound waves in given period
- Corresponds to pitch
- Greater frequency shrinks wavelength = high pitch
Outer Ear
Funnels sound waves into ear canal
1. Pinna
Middle Ear
Concentrates sound energies
1. Tympanic Membrane (Eardrum)
2. Ossicles
3. Oval Window
4. Round Window
Inner Ear
Converts sound into neural activity
1. Cochlea
- Scala vestibuli
- Scala media
- Scala tympani
Scala Media
Middle Canal of Cochlea
- Contains Organ of Corti
-
Tectorial Membrane
- Connects to vestibular canal
- Stereocilia protude from each hair cell & extend into membrane
Basilar Membrane
- Hair cells embedded into membrane
- Anchors auditory system to tympanic canal
- Higher frequencies displace base
- Lower frequencies displace apex
Vestibulocochlear Nerve
Cranial nerve that innervates inner ear
1. Hearing & sensation of balance
Inner v. Outer Hair Cells
Outer: Discriminates frequencies
- Expansion: stiffen & reduce vibration
- Contraction: relax & increase vibration
Inner: Perception of sound
Auditory Pathway
- Cochlear Nucleus
- Superior Olivary Nucleus
- Inferior Colliculus
- Medial Geniculate Nucleus (Thalamus)
- Temporal Lobe
Tonotopic Mapping
- Arrangement according to frequencies at which they respond
- Row of neurons respond to specific range of frequencies
- Apex: low frequencies
- Base: high frequencies
Vestibular System
- Detects position and movement of the head
- Three axes
- Pitch
- Yaw
- Roll - Mechanically-gated ion channel system
- Hair cells sway - perceives movement on three axes
Binaural Cues
- Intensity & Latency Differences
- Takes longer for sound waves to reach one ear than the other - Signal sound location
Streams of Information
- Dorsal: Where?
- parietal lobe - Ventral: What?
- temporal lobe