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10/22
Hearing Sciences
| Question | Answer |
|---|---|
| What is the point of a tuning curve? | Researchers are observing one part of the basilar membrane and finding the lowest level for a given frequency needed to causes that section of the basilar membrane to vibrate |
| Who picks the frequency of a tuning curve? | the tester |
| What can cause the tuning curve to be sharp or dull? | the function of outer hair cells |
| What makes a tuning curve dull? | dysfunctioning outer hair cells |
| What makes a tuning curve sharp? | Well functioning outer hair cells |
| What can cause outer hair cells not to work? | noise exposure, death, ototoxic medication |
| What is a tuning curve? | a plot of tones of different frequencies at different levels that will stimulate the part of the basilar membrane that is under observation |
| What is the implication of a dull tuning curve? | the outer hair cells are not working right now |
| What is an example of ototoxic medications? | aspirin in high doses, cancer medications |
| Why is the lowest point of a sharp tuning curve so low? | Because it is the characteristic frequency of that section of the basilar membrane |
| How are physiologic or neural tuning curves obtained? | by measuring the range of frequencies that produce a criterion increase in the discharge rate for a particular neuron |
| How are psychoacoustic (psychophysical) tuning curves obtained? | by measuring the range of frequencies that can interfere with (or mask) the perception of a target tone near threshold |
| What did Bekesy find while measuring the tuning of the basilar membrane in human cadavers? | tuning that was much broader than the tuning curves measured from individual auditory nerve fibers of the 8th nerve in live animals or in psychoacoustic experiments |
| How can tuning curves be described? | by what you are observing |
| What did Von Bekesy miss in his research? | the effects of the outer hair cells on a tuning curve |
| What is the passive process in the cochlea? | the relatively broad tuning of the basilar membrane that is related to the traveling waves that occur because of the width and stiffness of the basilar membrane |
| What is a relatively sharp basilar membrane tuning curve dependent on? | an active process seen only in a healthy, normal cochlea |
| What happens in the passive process of the cochlea? | there is no movement from the hair cells, but the basilar membrane is still moving |
| What did Gold (1948) conclude about the cochlea? | some active energy process was needed in the cochlea in order to have a sharp frequency tuning. It would involve an active feedback loop, which generates some vibratory energy in the cochlea |
| What did Kemp (1978) measure? | the Vibratory energy in the form of Otoacoustic emissions that Gold suggested |
| What is inside the external auditory canal? | air molecules |
| What did David Kemp do of importance? | He discovered the phenomenon of Otoacoustic emissions (OAEs) |
| What are Otoacoustic Emission instruments used for? | to determine the functionality of outer hair cells in all age ranges |
| What happens to the additional mechanical activity on the basilar membrane from otoacoustic emissions? | the energy can travel back out through the middle ear and can generate very low level acoustic sounds in the ear canal that can be measured with a very sensitive microphone |
| What did Brownell (1983) discover? | Outer hair cells were able to elongate and contract in response to electrical currents, referred to as the motility of outer hair cells |
| What is outer hair cells motility? | outer hair cells elongating and contracting in response to electrical currents |
| What happens to the motion of the basilar membrane during low to moderate sound pressure levels? | it is not a sufficient enough motion to make the stereocilia of the inner hair cells to move to the stimulating position |
| What is another name for outer hair cells? | the cochlear amplifiers |
| What does the active cochlear process of the outer hair cells do? | it amplifies the displacement of the basilar membrane through the motility of the outer hair cells |
| What happens to the active process in the cochlea due to damage to the outer hair cells? | the process is compromised and the result is often a mild to moderate hearing loss |
| What does the absence of otoacoustic emissions suggest? | some type of abnormality in auditory function, either in the outer hair cells, middle ear, or outer ear |
| What can cause the otoacoustic emissions to be absent? | outer hair cells not working, infections, fluid in the ear, broken ossicular chain, excessive ear wax buildup |
| What did Zhao and Stephens (2006) discover? | for individuals with normal audiograms, outer hair cells damage appears to be related to a decreased ability to recognize speech in the presence of background noise |
| What happens if the outer hair cells do not contract and expand for low level sounds? | the inner hair cells will not be stimulated and no signal will be sent to the brain via the afferent nerves fibers |
| What happens to outer hair cells at the peak of a traveling wave (Hamill & Price 2014)? | they increase the motion of the basilar membrane |
| What could be a secondary source of otoacoustic emissions (Hamill & Price 2014)? | stereocilia motion |
| What happens during the stimulation of the hair cells (Hamill & Price 2014)? | mechano-electrical transduction (MET) channels are opened in the stereocilia |
| What are cochlear potentials? | neuro-electrical activity in the cochlea |
| What does nature do if unimpeded? | it always seeks equilibrium |
| What happens in an unbalanced condition of energy potentials? | it results in electron flow that lasts until the atoms are in a a balanced state |
| The greater the disparity of electrons, the greater... | the charge and the potential for electrons to move in the quest for equilibrium |
| How can the magnitude of the charge be expressed? | as the potential for electrons movement or flow |
| How can the magnitude of the potential be expressed? | in volts (V) |
| What is a volt? | a statement of potential electron flow |
| What is an ion? | an atom or molecule with a net electric charge due to the loss or gain of one or more electrons |
| What happens to a surplus of electrons? | they have the potential to flow |
| What happens if ion concentrations are different? | potentials occur |
| Why do the fluids of the cochlea have different electrical charges? | they have different concentrations of ions |
| Endolymph is how much more positive than perilymph? | 100 mV |
| Inner hair cells are how much more negative than perilymph? | 40 mV |
| Outer hair cells are how much more negative than perilymph? | 70 mV |
| What are the hair cells bathed in? | cortilymph |
| What do we need for hearing? | electricity |
| What does the reticular lamina do in terms of cochlear potentials? | it separates the potassium (K+) rich endolymph from the hair cells |
| What is the potential for ion flow between the endolymph and the inner hair cells? | -140 mV |
| What connects the stereocilia? | tip-links |
| What does a small deflection do for hearing? | it is insufficient to open the microchannels in the stereocilia |
| How are the microchannels of the stereocilia open? | by bending away from the modiolus |
| What opens the microchannels of the stereocilia? | further deflection (bending away from the modiolus) |
| What happens with the microchannels of the stereocilia open? | K+ flows into the hair cell |
| What is depolarization? | When stereocilia move away from the modiolus (towards tallest cilia), microchannels open and potassium enters the normally negative hair cell, making it more positive |
| What generally happens during depolarization? | the hair cell becomes more positive |
| What happens when the cilia deflect towards the modiolus? | the hair cell can become more negative as the potassium is pumped out |
| What is a cochlear microphonic? | a recording of the fluctuating hair cell polarity (positive to negative) |
Created by:
hrshook0104
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