Tuesday, October 22, 2013

10/22/2013

10/22/2013

Answers:
What is the definition of "Hearing Threshold"?
A) Minimum frequency that is detectable 100% of the time
B) Minimum intensity that is detectable 100% of the time
C) Minimum frequency that is detectable 50% of the time
D) Minimum intensity that is detectable 50% of the time
E) Minimum frequency that is detectable on exam
F) Minimum intensity that is detectable on exam


Threshold = softest intensity of pure tone detected 50% of the time.

What is "Masking" and why is it used?

Masking is used because a noise given to one ear can often be heard on the other side. To prevent a nontest ear from hearing a sound presented to the tested ear, a noise is presented to the nontest ear to "distract" it and prevent it from responding to the test sound. This is called masking. Masking is needed for AC whenever AC-BC gap is 40db(for lower freq) or 60db(for high freq). Masking is needed for BC whenever an AC-BC gap occurs.

MC Questions:

An individual who has difficulty with soft or distant sound but understands most speech without cues and appreciates environmental sounds would likely have what type of hearing loss.
A) Mild (25-50db)
B) Moderate (50-70db)
C) Severe ( 70-90db)
E) Profound (90+)

Free Response Question:
What is the Stenger test? What is it used for?


Quick Facts:

Acoustic Reflex
-When the stapedius muscle contracts due to loud sound.
-Occurs at 70-90db above pts hearing threshold.
-Can measure reflex by measuring change in compliance after loud sound.
-Monaural stimulation causes b/l muscle contract so can measure ipsi or contra.
-R ipsi = stimulus r ear, probe r ear
-R contra = stimulus r ear, probe l ear
-L ipsi = stimulus l ear, probe l ear
-L contra = stimulus l ear, probe R ear.
-Mild/mod SNHL = contra and ipsi reflex are at same levels
-Sev/profound SNHL = acoustic reflexes absent.
-Large CHL = eliminates response to both ears when affected ear stimulated. When good ear stimulated may not get contra due to pathology of middle ear preventing stapedius contraction.
-Only reflex in unilateral CHL = ipsi reflex of normal ear.
-CN VIII lesions = eliminated reflex both contra and ipsi when affect side stimulated.
-path of central crossed pathways = both ipsi present, contra missing.
-VII lesion (Bell's palsy) = no reflex on affected side regardless of side stimulated, but only true id lesion is proximal to branch to stapedius muscle.

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