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Speech Audiometry
- better estimate of hearing handicap then pure tones because it incorporates sensitivity and acuity
- -they are not great diagnostic tools
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SDT-Speech detection Threshold
A measure of sensitivity, it is the lowest level in dB that a subject can detect speech. The speech does not need to be understood just need to be able to hear someone talking
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SRT- Speech recognition threshold
- Better than SDT and is also a sensitivity measure. The difference is the speech must be understood and is often tested with Spondees. (greyhound, sidewalk, mailman)
- -you test it in the same fashion as pure tones but the client must repeat the word.
- -this measure should agree with your pure tone average at 500, 1000 and 2000
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MCL
most comfortable listening leve
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Acuity measures
- the % correct supra measures
- -how well can acoustic cues of speech above threshold be distinguished
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word recognition scores (WRS)
- not a discrimination task and cannon be predicted by the pure tone audiogram
- -not good reliability or validity
- -can help with amplification, how much struggle, lesion site
- -the more words the better or more reliable it is
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OAE
- sounds produced by the cochlea, it is the sound of outer hair cells dancing. rules out middle and outer ear problems (conductive loss)
- -could still be an inner ear problem
- -they are used for neonatal screenings, early signs of NIHL, Malingering, ototoxicity monitoring
- -Spontaneous OAEs happen in the absence of input
- -evoked OAEs is when there is a response to our manipulation
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DPOAE- Distortion product OAE
- 2(f1)-f2= where to measure the DPOAE
- -not a test of hearing, only a test of OHC functioning. we use them to infer normal hearing. good for infants and dif populations
- -If there is no activity at the area we calculated(in the above equation) then there is an OHC malfunction
- -we measure the amplitude(dB)
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Auditory Evoked Potential
- sounds can cause certain centres of the auditory system to create a measurable output
- -ABR is a type of AEO: we measure them based on shape and latency
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ABR-Auditory brain stem response
- not a test of hearing, they test IHC and brainstem function
- -early latency response and happens automatically after stimulus in a healthy system
- -we use them for threshold estimates in hard to test populations
- OAE + ABR = good idea of problem area
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ABR waves
- 1. Cochlea + VIII CN function
- 2. VIII CN
- 3. Pons
- 4. Pons
- 5. Midbrain
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ABR wave outcomes
- At high intensities (70db) we should have clear responses from 1,3,5
- -then intensity is lowered until wave 5 (midbrain) is undetectable which is your ABR threshold
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info obtained from ABR
- 1. absolute latencies of all waves
- 2. interpeak intervals
- 3.wave amplitudes
- 4 threshold of wave V (midbrain)=as you near it the latency goes up and amplitude goes down
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ABR= Conductive hearing loss
will elevate thresholds by air and slow all waves down by the same amount
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ABR= Sensorineural
Prolong and elevate wave V threshold
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ABR=Retrocochlear lesions (tumours, MS)
- -prolong interpeak intervals,
- -wave V latency different between ears
- -amplitude ratios are abnormal (wave 5 is usually larger than wave 1)
- -wave V is prolonged or absent at high intensities
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VRA visual reinforcement audiometry
kid turns to sound then is reinforced with a toy of some sort that is lit up in a box. appropriate for kid 7-30 months. Must condition the response first
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Play audiometry
- 30m-5 years approx
- start at 50db to teach the game then start the test
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