Lecture 23 Hearing Assessment Flashcards
What are the 4 steps/tests to diagnose hearing loss.
- Examine the ears- ear canal.
- test the middle ear function
- sensitivity hearing test
- speech recognition testing
What are the 3 factors to consider when diagnosing the specific type of hearing loss
- Type of hearing loss:
- conductive (outer + middle ear): these can be temporary, and addressed surgically
- sensorineural (cochlear onwards): these are typically permanent
- mixed (both)
- central lesion - Site of lesion
- Degree of loss.
What is a Cholesteatoma
Tumour grown by epithelial cells when someone has repeated ear infections which can obstruct middle ear bone functions
What disease can cause TM perforation
Hepatitis
What are signs of sensorineural hearing loss and why do they happen
Loss of loudness, clarity and resolution of sound - in speech some consonants are softer than others eg. p,n,g. can’t be heard compared to vowels.
This is because of hair cells dying unable to transmit electrical nerves to some auditory nerves that survive.
Why is Auditory Brainstem Response (ABR) useful
Can stimulate along the brainstem to find the site of lesion, find hearing threshold. Also objective test.
What are some Behavioural vs Objective hearing tests.
A combination of these is used to diagnose hearing loss
- Behavioural: requires voluntary response
- Pure tone audiometry: air conduction/bone conduction
Modifications for children: ( Lights, puppet,)
- Visual response audiometry, -
- Conditioned play audiometry:
Word recognition assessment
- Objective: how the ear drum and reflexes working.
- Tympanometry
- Acoustic Reflex threshold & decay
- Otoacoustic Emissions
- Evoked Potential Assessments: ABR and cortical evoked potentials
What does the audiogram measure and how is severity considered.
Blue: left, red= right ear
measures the level of sound that people can detect across frequency. (x: Hz, y: dB).
Record the softest sound possible to be heard at specific frequencies
The severity of hearing loss is related to needing to have a louder dB for the same frequency.
Normal, mild, moderate, moderately severe, severe, profound hearing loss.
What does audiogram look like for conductive vs sensorineural loss
C: straight line but at a higher dB. When bone conduction, then hearing lines are normal
S: Staring off at higher dB, the slope goes down as the frequency increases.
What is the difference between cochlear implant and hearing aid
Hearing aid: acoustically amplify the sound through the outer and middle ear to stimulate travelling wave in hair cells.
Cochlear implants: relies on surviving neural elements. It bypasses damaged hair cells to stimulate the nerve directly, convert acoustic input signal into electrical pattern transmitted by FM through skin to internal device delivered to electrodes in scala tympani.
How do you treat someone with no cochlear nerve but still auditory cortex
Auditory brain implant which presents sound electrically at the cochlear nucleus
Who are eligible for cochlear implants (40 subsidised) - N and S clinics.
Children:
- meningitis caused sensorineural hearing loss
- bilateral severe hearing loss or worse
- limited aided speech info above 2khz/ severe reverse sloping hearing loss or worse
- auditory neuropathy spectrum disorder
Adults:
- Bilateral moderate to profound sensorineural hearing loss with limited or no useful benefit from hearing aids. (No max age)
What are the 3 stages of ongoing monitoring of child hearing in early intervention programme
- At birth all babies offered hearing screening which should be completed by 1 month
- By 3 months They should have hearing evaluation: diagnostic audiology
- By 6 months is ideal age for early intervention services
