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21 Cards in this Set
- Front
- Back
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What does the outer ear consist of? |
Pinna Ear canal Eardrum |
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What is the purpose of the outer ear? |
To collect sound waves. |
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What frequency is the ear canal? |
3800Hz. |
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What does the pinna do? |
Collect sound and allow directional hearing. |
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Define binaural disparity. |
Two ears picking up different frequencies. Provide dominant cues. |
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What does the middle ear consist of? |
Hammer (malleus) Anvil (incus) Stirrup (stapes) |
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What is the purpose of the middle ear? |
To transfer vibrations to the oval window. |
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What is the eustachian tube? |
The connection between the middle ear and the back of the throat. It is filled with air. Discomfort/pain can arise due to the difference in pressure across the eardrum. This can be resolved by swallowing and enable pressure equalisation. |
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What happens when there is no middle ear? |
Less than 1% of energy would pass through to the inner ear. The rest would get reflected back out. |
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What is the acoustic reflex? |
It is when muscle pulls the stirrup back from the oval window to reduce the damage when very loud sound is heard. It takes 1/10 second to react and is only effective for 1000Hz. |
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What does the inner ear consist of? |
Cochlea - basilar membrane, organ of corti and helicotrema Semicircular canals |
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What is the purpose of the inner ear? |
To transfer sound energy to the brain. |
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Describe the cochlea. |
It is 35 mm long. Coiled up in 2.5 turns around modiolus. |
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Describe the basilar membrane. |
It has a tonotopic structure - high near the base and low near the apex. Place theory - our perception of hearing is dependent on where frequencies vibrate on the basilar membrane. |
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Describe the organ of corti. |
4 rows of hair cells - 3 OHC and 1 IHC. Arranged along basilar membrane. |
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What is the helicotrema? |
Where the upper and lower galleries connect. |
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What is the purpose of the semicircular canals? |
Gives balance to the head. |
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What is the critical band? |
A range of frequencies that are perceived by the ear as the same pitch. |
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How do we perceive different pitches? |
Two frequencies are at least one critical bandwidth apart. Around 1.3mm across basilar membrane. For tones under 500Hz, the critical bandwidth is constant at 100Hz. |
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Define beating.
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Periodic flunctuation in amplitude of combined signal. When two frequencies have bandwidths largely overlapping. |
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Define roughness. |
Two frequencies separated by more than one critical bandwidth, gradually reducing frequency separation. Semitones create the most roughness. |
