Audition Flashcards
What is sound? (Three things)
- Loudness: Amplitude of the soundwave
- Pitch: Frequency of the soundwave
- Timbre: Complexity of the soundwave
How do we hear?
Sounds make the ossicles vibrate against the cochlea
2. The vibrations make the fluid inside the cochlea move
3. Fluid movements deforms the basilar membrane
=> high pitch sound: deformation at the base of the membrane
=> low pitch sound: deformation at the tip of the membrane
What are Inner hair cells?
Transmit auditory information to
the brain
• Sway back and forth as the basilar
membrane and the endolymph moves
• Without them = deaf
What are Outer hair cells?
• Attached to the tectorial membrane
• Act as a muscle to adjust the flexibility of the tectorial membrane
How do hair cells send signals?
▪ Vibration in the basilar membrane makes the cilia rub and bend against the tectorial membrane.
▪ The stretching of tip links open ion channels
List the path from the ear to the brain (6 steps :))
- Temporal Lobe: Primary auditory cortex
- Thalamus: Synapse in the medial genicular nucleus
- Midbrain: Synapse in the inferior colliculi
- Medulla: Synapse in the superior olivary nuclei
- Medulla: Synapse in the dorsal and ventral cochlear nuclei
- Cochlear Nerve
What is place coding?
• Moderate to high frequency is recorded by place coding. Human speech is in this frequency range!
• Position of the active hair cell on the basilar membrane indicates the pitch
• Higher frequencies =base of basilar membrane (narrow)
• Lower Frequency: tip of the basilar membrane (wide)
What is Rate Coding?
Very low frequencies are encoded by rate coding
Short summary of what inner hair cells and outer hair cells do.
Transmit information to the brain. Without it = deaf
Change sensitivity of tectorial membrane to vibration -> tune sensitivity & frequency selectivity of inner hair cell. Without it = hearing deficiency
How do we perceive loudness?
number of hair cells that are active
Loud sounds
• tip link stretches to their max and break.
• Temporary loss of hearing
• Prevent excitotoxicity
What is timbre specifically?
Complexity of the sound.
specific mixture of fundamentals and overtones that different instruments emit when the same note is played.
Precise mixture of hair cells active
How do we tell where sounds are coming from?
- Phase Difference
• Low Frequency sounds
• Timing difference between
ears - Level Difference
• High Frequency sounds
• Loudness difference
between ears - Timbre Difference
• Changes in timbres between difference location of the sounds
What is Amusia?
• Cannot perceive music
• Can understand speech
• Can recognize emotions in music but would not be able
to tell if it’s a consonant/dissonant music
Why? The characteristics of music (melody, rhythms and harmony) and how you perceive it (pleasant, unpleasant) are processed in a different regions of the auditory association cortex
