Hearing Assessment and the Diagnosis of Hearing Loss Flashcards
What specific questions are we attempting to answer when determining if there is hearing loss?
We want to determine if there is a hearing loss, how severe it is, and where in the auditory system does the problem come from.
How is hearing threshold defined?
It is the minimum level at which a person can hear fifty percent of the time.
Describe the relationship between air conduction and bone conduction in normals, conductives, sensorineurals, and mixed losses.
Normal: AC is normal; BC is normal. If hearing is good for AC no test for BC is required.
Conductives: AC is abnormal; BC is normal. air/bone gap (AC, BC vary).
Sensorineural: AC is abnormal, BC is abnormal. Equally abnormal BC b/c problem is in inner ear.
Mixed Losses: problem is in both cochlea and conductive mechanism. Ex.) old man with presbycusis and otitis media: AC is worse than BC b/c it is the measure of the entire auditory system; air/bone gap, when conductive disorder is treated, air/bone gap goes away, audiogram looks like sensorineural
What is the purpose of the SRT?
Speech recognition threshold: a reliability measure that determines the threshold for speech. It is based on the notion that our threshold for pure tones and speech should be very similar.
What is the purpose of the word recognition test?
It measures our ability to understand monosyllables when presented at comfortable level. Sensorineurals losses respond abnormally.
Differentiate validity and reliability
validity: measure what it purports to measure; reliability: can be repeated
How do we assure reliability in audiologic assessment?
We calibrate equipment to be sure that the stimuli delivered to a patient is what we purport it to be. Also, compare different tests to one another to determine agreement.
What are the three subcomponents of immittance testing?
Tympanometry, static admittance, and acoustic reflexes
What does tympanometry measure?
It measures eardrum mobility under a variety of pressure conditions, positive and negative. We want to know under what pressure the eardrum moves most easily b/c when pressure on both sides of the ear drum is similar the eardrum will move most easily
What does static admittance tell us?
It tells us if the eardrum allows energy to flow through the middle ear normally.
What does measurement of the acoustic reflex tell us?
It is the measure of the intensity needed to evoke a contraction of the middle ear muscles. People with conductive or neural hearing loss might have absent or elevated reflexes. People with normal or cochlear hearing loss usually have normal reflexes.
What diagnostic data can be determined from the procedures of immittance testing?
We can determine if there is a middle ear problem
How are evoked potentials measured?
These tests involve the placement of electrodes on the scalp while earphones deliver sounds to the patient. We compare responses (brainwaves) in normals to the individuals being tested.
What might abnormal response on evoked potential tests indicate?
Abnormal responses can indicate the presence of tumors, abnormal development, other diseases, or learning problems.
The OAE can be elicited in two ways. Name them.
Spontaneous (naturally occurring) or evoked (occur after a sound stimulus is presented to the ear)
