423349
Description
Mind Map by natalieclark29, updated more than 1 year ago
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Created by natalieclark29
almost 11 years ago
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Physiology of Hearing
- Function of Hearing
- Sounds are created when objects vibrate
- Vibrations of object cause molecules in object’s surrounding medium
to vibrate as well, which causes pressure changes in medium.
- Vibrations of object cause molecules in object’s surrounding medium
to vibrate as well, which causes pressure changes in medium.
- Sound waves and air pressure
- Sound travels through air at 340 m/s
- Sound travels through air at 340 m/s
- Basic sound wave qualities
- Amplitude
- Intensity
- Frequency
- Amplitude
- Perceptual components of sound
- Pitch
- Loudness
- Duration
- Timbre
- Pitch
- Hearing
- 20 - 20000 Hz
- Ratio between the faintest and loudest sound is more than 1:1,000,000.
- 20 - 20000 Hz
- Sounds are created when objects vibrate
- Mammalian Auditory System
- Outer ear
- Sounds collected by pinnae
- Funnelled from pinnae to ear canal
- Length and shape of ear canal enhance sound frequencies
- Length and shape of ear canal enhance sound frequencies
- Funnelled from pinnae to ear canal
- Main function is to insulate the tympanic membrane
- Sounds collected by pinnae
- Middle ear
- Ossicles
- Stapes
- Transmits vibrations to oval window
- Transmits vibrations to oval window
- Incus
- Malleus
- Stapes
- Muscles
- tensor tympani
- Stapedius
- Muffle pressure changes
- But there's a delay of 1/5 of a second so cannot protect against abrupt noises
- But there's a delay of 1/5 of a second so cannot protect against abrupt noises
- tensor tympani
- Ossicles
- Inner ear
- Changes in sound pressure transform into neural signals
- Cochlea
- Contains organ of Corti
- specialised neurons called hair cells, dendrites of auditory nerve fibres
that terminate at base of hair cells, and scaffold of supporting cells
- Inner Hair Cells carry most (90%) of the information out of the cochlea
- Outer Hair Cells receive majority of information into the cochlea
- sharpen the displacement pattern of the basilar membrane
- improve sensitivity to sound; they make response thresholds lower.
- Works by motility of the hair cell body and/or the stereocilia
- Damage leads to broad tuning
- sharpen the displacement pattern of the basilar membrane
- specialised neurons called hair cells, dendrites of auditory nerve fibres
that terminate at base of hair cells, and scaffold of supporting cells
- Canals
- Tympanic
- Vestibular
- Middle
- Tympanic
- Membranes
- Reissner's
- Basilar
- cannot account for the sharpness of frequency in the auditory system
- cannot account for the sharpness of frequency in the auditory system
- Reissner's
- Contains organ of Corti
- Changes in sound pressure transform into neural signals
- The auditory nerve
- Responses of individual AN fibres to different frequencies
are related to their place along the cochlear partition
- Frequency selectivity: clearest when sounds are very faint.
- Threshold tuning curve
- rate saturation
- isointensity curves
- isointensity curves
- Rate intensity
- Responses of individual AN fibres to different frequencies
are related to their place along the cochlear partition
- Auditory cortex
- Tonotopic organisation
- Maintained in primary auditory cortex (A1)
- Neurons from A1 project to belt area, then to parabelt area
- Maintained in primary auditory cortex (A1)
- Tonotopic organisation
- Outer ear
- Hearing Impairment
- Obstruction
- Ear wax
- Ear wax
- Conductive hearing loss
- Caused by problems with the bones of the middle
ear, (e.g., during ear infections, otitis media)
- Caused by problems with the bones of the middle
ear, (e.g., during ear infections, otitis media)
- Otosclerosis
- More serious type of conductive loss.
- Caused by abnormal growth of middle ear bones; can be remedied by surgery
- More serious type of conductive loss.
- Sensorineural hearing loss
- Injured hair cells
- Injured hair cells
- Hearing loss
- Consequence of aging
- Consequence of aging
- Obstruction
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