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30 Cards in this Set
- Front
- Back
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Tympanometry components |
Air pump, loudspeaker, microphone (with probe tip measuring the sound pressure level SPL) |
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Tympanogram (x axis) |
Middle ear pressure in daPa |
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Tympanogram (y axis) |
Immitance (compliance/flexibility) |
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Static acoustic compliance |
Maximum compliance value |
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Static acoustic compliance normal range and pathologies |
0.3-1.6
Less than 0.3 (otitis media, otosclerosis, thick eardrum)
More than 1.6 (ossicular chain discontinuity, thinned eardrum) |
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Eer canal volume (ECV) normal range and pathologies |
0.2-2.0ml Less than 0.2ml: cerumen/ foreign body More than 2.0ml: eardrum perforation/ PE tube |
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Type A tym - Normal -Peak compliance 0.30-1.50 ml @ 0 daPa -Peak pressure:+100 to -100 daPa (up to -150 daPa for child) |
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Type Ad tym - Highly compliant - Path: ossicular chain discontinuity/ flaccid eardrum |
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As tym - Shortened v-shape - Indicate stiffness of the middle ear - Path: otosclerosis/ scarred eardrum |
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Type B tym - No sharp peak/little variation in impedance -Indicate severely restricted mobility of eardrum - Path: middle ear effusion/ perforated eardrum/ blocked probe/ blocked ear canal |
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Type C tym - Peak beyond -100/-150 daPa - Path: eustachian tube dysfunction/ ceetain stages of middle ear infection |
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Malleus muscle, innervation |
Tensor tympani, nerve V (trigeminal nerve) |
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Stapes muscle, innervation |
Stapedius, nerve VII (facial nerve) |
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Acoustic reflex (normal value, mechanism) |
- Above 70 dbHL - Stapedius muscle contracts and pulls the stapes away from the oval window. - This stiffens the ossicular chain. - Decreasing the vibration to cochlea. - Happens to both ears even though the stimulus is presented in one ear only. |
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Acoustic reflex arc |
Acoustic Reflex Measures: Pathways • Afferent structures consist of the cochlea and the auditory portion of the eighth cranial nerve.• Afferent pathways carry information from the ear to the brain. • The cochlear nucleus (nuclei) in the brainstem contribute (s) to the acoustic reflex arc in both ipsilateral and contralateral measurement conditions. • Additional neurons in the trapezoid body and medial superior olivary complex contribute to the acoustic reflex pathways in the contralateral measurement condition. Acoustic Reflex Measures: Pathways• A descending efferent pathway passes from the brainstem back to the ear. • The descending (efferent) pathway includes motor fibers within the 7th (facial) cranial nerve, particularly a small branch that innervates the stapedius muscle. • Ipsilateral acoustic reflex pathways remain on one side of the body and are sometimes described as an uncrossed acoustic reflex. • Contralateral pathways are often described as crossed acoustic reflexes. |
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ART normal value |
Acoustic reflex threshold • 80-105 dB ART for 0-50 dB HTL• SL = 55-85 dB |
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How to administer acoustic reflex decay test? |
Acoustic reflex threshold is determined for one ear with a stimulus, like a 1000 Hz tone. Next, the same stimulus is presented continually for 10 seconds at an intensity level 10 dB higher than the threshold.
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Administering OAE and normal value |
Otoacoustic emissions
- OAE measurements begin with insertion of probe into ear canal. - Probe presents stimulus + detects very faint sounds from cochlea. - 有hair cell motility (lengthening and shortening of hair cells) 先有OAE - OAE normal level: 0-15 dB SPL - >6dB=OAE present |
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Acoustic reflex decay test usage |
To indicate auditory nerve or auditory brainstem problem rather than inner ear |
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Tympanogram usage |
To imdicate middle ear involvement |
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Types of OAEs |
Spontaneous OAEs (SOAEs) Transient evoked OAEs (TEOAEs) Distortion product OAEs (DPOAEs) |
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TEOAE value |
- Presented at 80 dBSPL - 0-4000 Hz of TEOAE energy recorded |
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DPOAEs value |
- High fequency to low frequency=1.2 - Intensity level at 55 to 65 dBSPL - DPOAEs recorded at 500-8000 Hz |
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OAE usage |
- To distinguish sensory (inner ear hair cell problem) from neural problem - Indirectly indicate normal middle ear function - Provide evidence that outer hair cells for that portion of the cochlea is intact |
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ABR mechanism and administration |
Auditory brainstem response - Reflects auditory nerve fibre and pathways withij auditory brainstem - Summed electrical activity from nerve fibres firing is picked up with electrodes on the forehead and near the ears - These electrical reaponses must pass through brain tissue to electrodes on skin - ABR repeatedly recorded at progressively lower stimulus intensity for click and tone burst stimuli at different frequencies |
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ABR wave types and meaning |
I: auditory nerve near cochlea III: pons of auditory brainstem V: midbrain of auditory brainstem |
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Interpreting ABR |
Latency analysis Amplitude analysis |
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ABR usage |
Estimate auditory thresholds in infants and young children |
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Hearing Ax for children below 6 mos |
Acoustic immitance (equivalent volume of ear canal, static acoustic compliance of middle ear tympanometry, acoustic reflex) Otoacoustic emissions ABR |
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Acoustic reflex presence test usage |
Absence=abnormal middle ear functioning |
