Lecture 16 Flashcards
Pinna helps with ___ ___
Pinna helps with sound location
Auditory canal is a ___-like 3 cm long structure that protects the ___ ___ (ear drum) at the end of the canal
Auditory canal is a tube-like 3 cm long structure that protects the tympanic membrane (ear drum) at the end of the canal
Resonance
occurs when sound waves that are reflected back from the tympanic membrane interact with sound waves entering the canal, which can reinforce (increase the intensity of) certain frequencies
The auditory canal amplifies frequencies between 1,000 and 5,000 Hz (which is the canal’s ___ ___, or the frequency that is most reinforced)
The auditory canal amplifies frequencies between 1,000 and 5,000 Hz (which is the canal’s resonant frequency, or the frequency that is most reinforced)
The __ __ is a two cubic centimetre cavity separating the inner ear from outer ear
The middle ear is a two cubic centimetre cavity separating the inner ear from outer ear
The middle ear contains 3 __ (which are the smallest bones in the human body): ___, ___, and ___
The middle ear contains 3 ossicles (which are the smallest bones in the human body): malleus, incus, and stapes
Malleus (hammer)
moves due to the vibration of the tympanic membrane (ear drum)
Incus (anvil)
transmits vibrations of the malleus
Stapes (stirrup)
transmits vibrations of the incus to the inner ear (via the oval window of the cochlea)
While the outer and inner ear are filled with __, the inner ear is filled with ___ that is much denser than air. This causes pressure changes in __ to transmit __ into the denser medium (the __). The ossicles helps to amplify these vibrations for better transmission.
While the outer and inner ear are filled with air, the inner ear is filled with fluid that is much denser than air. This causes pressure changes in air to transmit poorly into the denser medium (the liquid). The ossicles helps to amplify these vibrations for better transmission.
The middle ear muscles also ___ the ossicles’ vibrations to protect the inner ear from potentially damaging stimuli when exposed to ___ ___ sound waves
The middle ear muscles also dampen the ossicles’ vibrations to protect the inner ear from potentially damaging stimuli when exposed to high amplitude sound waves
Two properties of the middle ear assist with amplifying the sound:
1) By ___ the vibrations of the large tympanic membrane onto the much smaller ___
2) By being hinged and therefore creating ‘___ action’ which amplifies a small force
Two properties of the middle ear assist with amplifying the sound:
1) By concentrating the vibrations of the large tympanic membrane onto the much smaller stapes
2) By being hinged and therefore creating ‘lever action’ which amplifies a small force
Cochlea
main structure of the inner ear, and the location at which transduction of pressure waves occurs
The cochlea is divided by the __ ___ that divides it into 2 sections: the upper half (Scala __) and the lower half (Scala __)
The cochlea is divided by the cochlear partition that divides it into 2 sections: the upper half (Scala vestibule) and the lower half (Scala tympani)
___ of ___ is located within the cochlear partition and contains inner and outer hair cells, which are the receptors for hearing
Organ of Corti is located within the cochlear partition and contains inner and outer hair cells, which are the receptors for hearing
___ ___ supports the organ of Corti and vibrates in respond to sound
Basilar membrane supports the organ of Corti and vibrates in respond to sound
___ ___ extends over the hair cells
Tectorial membrane extends over the hair cells
The ‘back and forth’ motion of the oval window transmits vibrations to the liquid inside the cochlea:
puts the basilar membrane into an ‘_____’ motion, puts the tectorial membrane into a ‘____’ motion
The ‘back and forth’ motion of the oval window transmits vibrations to the liquid inside the cochlea:
puts the basilar membrane into an ‘up-and-down’ motion, puts the tectorial membrane into a ‘back and forth’ motion
___ (parts of the outer hair cells)bend in response to movement of organ of Corti and the tectorial membrane
Stereocilia (parts of the outer hair cells)bend in response to movement of organ of Corti and the tectorial membrane
Movement in one direction opens ion channels in the ___ ___ (parts of the stereocilia). Movement in the other direction closes the ion channels
Movement in one direction opens ion channels in the tip links (parts of the stereocilia). Movement in the other direction closes the ion channels
Phase locking
nerve fibres firing at/near peak of sound wave, and are thus “locked in phase”. Groups of fibres fire with periods of silent intervals, creating a pattern of firing. Carries temporal information that may assist with pitch perception
Bekesy’s Place Theory of Hearing
proposed that the frequency of sound is indicated by the place on the organ of Corti that has the highest firing rate
Bekesy noticed that the basilar membrane’s vibration was like a __ ___ (e.g. imagine holding a rope and ‘snapping’ it, then watching the resulting wave travel down the length of the rope)
Bekesy noticed that the basilar membrane’s vibration was like a travelling wave (e.g. imagine holding a rope and ‘snapping’ it, then watching the resulting wave travel down the length of the rope)
Because the amount of displacement on the basilar membrane is a function of frequency, we can think of the cochlea as effectively functioning like a ___
Because the amount of displacement on the basilar membrane is a function of frequency, we can think of the cochlea as effectively functioning like a filter
cochlea shows an orderly map of frequencies along its length, which can be referred to as __ organization
cochlea shows an orderly map of frequencies along its length, which can be referred to as tonotopic organization
Apex responds best to __ frequencies
Apex responds best to low frequencies
Base responds best to __ frequencies
Base responds best to high frequencies
Pure tones can be used to determine the threshold for specific frequencies measured at single neurons, which can then be used to produce ___ ___ ___ curves
Pure tones can be used to determine the threshold for specific frequencies measured at single neurons, which can then be used to produce neural frequency tuning curves
Frequency to which the neuron is most sensitive is the ___ ___
Frequency to which the neuron is most sensitive is the characteristic frequency
New research with live membranes shows that the entire outer hair cells respond to sound by ___ ___ and a change in __
New research with live membranes shows that the entire outer hair cells respond to sound by slight tilting and a change in length
Higher ___ = lower sensitivity = __ hearing
Higher threshold = lower sensitivity = worse hearing
Place theory
suggests the pitch perception is based on the relation between a sound’s frequency and the place along the basilar membrane that is activated
The effect of the missing fundamental could be explained by assuming the ___ also vibrate the membrane, and that the ___ of the intervals is informative of the fundamental
The effect of the missing fundamental could be explained by assuming the harmonics also vibrate the membrane, and that the spacing of the intervals is informative of the fundamental
The lower harmonics produced by tones tend to create distinct neural responses, which are referred to as ___ harmonics
The lower harmonics produced by tones tend to create distinct neural responses, which are referred to as resolved harmonics
Higher harmonics tend to create neural responses that are not clearly distinguishable, and are referred to as ___ harmonics
Higher harmonics tend to create neural responses that are not clearly distinguishable, and are referred to as unresolved harmonics
Primary auditory cortex (auditory receiving areas or A1 in temporal lobe) can be divided up into 3 general subregions ….
1) Core area
2) Belt area
3) Parablet area
Noise-induced hearing loss
acute exposure to very loud noises can severely damage the hair cells in the organ of Corti
Hidden hearing loss
refers to situations in which individuals may have normal results e.g. thresholds in a standard hearing test using pure tones played in isolation, yet have difficulty perceiving more complex ‘real-world’ sounds
If the hair cells are functioning normally yet the auditory nerve is not, this could produce ___ ___ ___
If the hair cells are functioning normally yet the auditory nerve is not, this could produce hidden hearing loss
Presbycusis
results from the cumulative effects of exposure to noise over time, greatest loss at high frequencies, affects males more severely than females, can be caused by exposure to some drugs
Cochlear implants are made up of
a microphone worn behind the ear, a sound processor, a transmitter mounted on the mastoid bone, a receiver surgically mounted on the mastoid bone
DeCasper and Fifer found evidence that infants’ recognize their mother’s voice as early as ___ ___ after birth
DeCasper and Fifer found evidence that infants’ recognize their mother’s voice as early as 2 days after birth
