Hearing L2

Question 1

T Or F?

The pattern of vibration is not dependent on which end of the cochlea is stimulated.

Answer 1

T

Question 2

what are otoacoustic emissions

Answer 2

sound emmisions from the inner ear

Question 3

are the outer hair cells capable of shape changes?

Answer 3

yes

Question 4

OHCs are capable of shape changes - depolarisation of the cell causes length ______; hyperpolarisation of the cell causes length _______.

Answer 4

OHCs are capable of shape changes - depolarisation of the cell causes length decreases; hyperpolarisation of the cell causes length increases.

Question 5

what happens when outer hari cells stop working well?

Answer 5

With total loss of OHC function there is a ~ 55 dB loss in thresholds.

Question 6

what are the OHC responsible for?

Answer 6

sensitivity, sharpness of tuning, and oto-acoustic emissions

Question 7

role of the iHC?

Answer 7

The inner hair cells (IHCs) act to transduce the mechanical events in the cochlea to electrical events in auditory-nerve fibres

Question 8

how are the OHC involved in a feedback mechanism?

Answer 8

Question 9

describe the The tip-link hypothesis of mechanotransduction

Answer 9

stereocilia are stretched towards the tallest stereocilia (or kinocilium in the vestibular apparatus) the probability of mechanically-gated channels opening increases; if they are stretched away from the tallest stereocilia the probability of them closing increases

Question 10

Answer 10

Question 11

where is teh alrgest current changes in hair cells?

Answer 11

at the tips of the steocilia

Question 12

whats the predominant ion in the endolymph

Answer 12

K+

Question 13

which ion is likely to carry the transucer current in hair cells?

Answer 13

K+

Question 14

describe the K+ gradient for hair cells

Answer 14

The resting membrane potential of the cell (-50 mV) coupled with the large endocochlear potential (EP) of +100 mV gives a total gradient of 150 mV

Question 15

what controls the compositiong of the endolymph?

Answer 15

Stria vascularis.

Question 16

Answer 16

Question 17

what is meant by presbycusis

Answer 17

Our hearing thresholds elevate with increasing age (presbycusis)

Question 18

Thresholds for both men and women are _______- in the high frequencies than the lower frequencies.

Answer 18

Thresholds for both men and women are poorer in the high frequencies than the lower frequencies.

Question 19

Answer 19

Question 20

The greatest factor underlying
presbycusis appears to be …..

Answer 20

The greatest factor underlying presbycusis appears to be the loss of the endocochlear potential arising from lateral wall degeneration with age.

Question 21

how can we selectively lower the EP in one ear?

Answer 21

To test this hypothesis, it is possible to selectively lower the EP in just one ear by application of furosemide to the round window.

The resulting threshold loss seen with a reduction in the EP mimics that seen presbycusis; a relatively flat loss at low frequencies and a sloping loss at high frequencies.

Question 22

descrieb Otoacoustic emissions (OAEs)

Answer 22

• Sounds that may be measured in the external auditory meatus
• may be ovoked by sound or occur spontaneously
• strongest piece of evidence for an active process
• Patients with a significant sensorineural hearing loss lack OAEs.

*

Question 23

when are OAEs useful?

Answer 23

The measurement of emissions is particularly useful in neonates where it is difficult to establish the absence of hearing

Question 24

Distortion product evoked otoacoustic emissions (DPOAEs) are generated with the presentation of…..

Answer 24

Distortion product evoked otoacoustic emissions (DPOAEs) are generated with the presentation of two tones (aka the primaries, f1 and f2) and the largest of these emissions occurs at the frequency 2f1 – f2.

Question 25

compare inner and outer hair cells

Answer 25

Question 26

how do inner hair cells interact with the auditory nerve cells?

Answer 26

Inner hair cells release glutamate from ribbon synapses that act on AMPA receptors on the primary afferents (i.e. the auditory nerve fibres)

Question 27

Temporal adaptation in a high spontaneous rate auditory nerve fibre describe the process of adaptation

Answer 27

Adaptation to a tone burst probably takes place at the hair cell/afferent fibre synapse

Question 28

how can we think of the output from the auditory nerve?

Answer 28

The output of the auditory nerve can be thought of as a set of parallel, overlapping, bandpass filters. filters are narrower at higher frequencies.

Question 29

how do we calculate the Q10dB

Answer 29

Question 30

example of a QdB10 calculation

Answer 30

Question 31

as the charactersitic frquency increases, the Q10dB ? increases or decreases

Answer 31

increases

Question 32

what is frequency resolution?

Answer 32

Frequency resolution (the ability to detect one frequency component of a multi-frequency complex stimulus, when all components are presented simultaneously)

Question 33

where is frequency resolution determined?

Answer 33

at the level of the basilar membrane. That is, the psychophysical bandwidths and the neural bandwidths recorded in the same species overlap

Question 34

fat

Answer 34

mamba another tough deck