Bone Conduction
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Frequencies tested: 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz
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Placement: Mastoid
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Symbols:
- Right ear (unmasked): <
- Left ear (unmasked): >
- Right ear (masked): [
- Left ear (masked): ]
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Tests cochlear function, bypasses outer/middle ear
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Occlusion effect: Occurs mostly at low frequencies when ears are covered
Masking Rules for Bone Conduction
Deliver narrowband masking noise to the NTE when the difference between the measured AC and BC thresholds of the TE is 15 dB or greater
Initial Amount of Masking in NTE = ACNTE + 10 dB + OE
Initial Amount of Masking in NTE for 500Hz = ACNTE + 10 dB + 15 dB = ACNTE +25 dB
Initial Amount of Masking in NTE for 1000Hz = ACNTE + 10 dB + 10 dB = ACNTE +20 dB
Initial Amount of Masking in NTE for 2000Hz = ACNTE + 10 dB + 0 dB = ACNTE +10 dB
Initial Amount of Masking in NTE for 4000Hz = ACNTE + 10 dB + 0 dB = ACNTE +10 dB
Occlusion Effect
textbook pg 153
| Frequency (Hz) | 250 | 500 | 750 | 1000 | 1500 | 2000 | 3000 | 4000 |
|---|---|---|---|---|---|---|---|---|
| Occlusion Effect (dB) | 15 | 15 | 15* | 10 | 0 | 0 | 0 | 0 |
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- = estimated value