Lecture 8 - Clinical Masking Flashcards

1
Q

What is effective masking?

A

of dB that a masker shifts threshold of a test signal (in same ear), relative to quiet

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2
Q

What is actual masking?

A

How much a certain amount of masking has shifted a person’s threshold

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3
Q

What is the purpose of clinical masking?

A

Put in masking in non-test ear to shift threshold in that ear so that it doesn’t perceive signal that crossed over

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4
Q

In what situations can you mask?

A
  1. Pure tone air conduction assessment
  2. Pure tone bone conduction assessment
  3. Speech recognition threshold assessment
  4. Suprathreshold speech recognition testing
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5
Q

What is interaural attenuation?

A

The loss of signal intensity as the sound travels to the non-test cochlea

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6
Q

What is the interaural attenuation for pure tone air conduction?

A

Supra-aural earphones: 40-50 dB

  • Due to through-the-head transmission (bc)
  • Partially because of around-the-head transmission (ac)

Insert earphones, deep insertion: 75 dB

  • Smaller amount of leakage
  • Less through the head transmission
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7
Q

What is the interaural attenuation for bone conduction?

A

0-10 dB

  • Vibration of the skull
  • The most sensitive cochlea responds to BC testing
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8
Q

When do I mask? (supra-aural earphones)

A

When the AC threshold in the test ear (TE) is 40 dB less than or equal to the bone conduction threshold in the non-test ear (NTE)

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9
Q

How can you use the Hood Plateau Technique for calculating the initial masking level?

A
  1. Start out with 10 dB + the AC threshold in the non-test ear
  2. Re-assess masked threshold in test ear
  3. Increase effective masking level by 5 dB in non-test ear
  4. Reassess threshold in test ear
  5. Continue until you reach a masked threshold in test ear that remains stable over 15-20 dB of increments in EML in NTE
  6. The masked threshold = true threshold in test ear
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10
Q

How can you determine the minimum and maximum masking level for pure tone AC thresholds?

A

Minimum Masking Level
Min EML = AC threshold (TE) - 35 dB + air-bone gap (NTE)

Maximum Masking Level
Max EML = BC threshold (TE) + IA (by AC)

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11
Q

When should you mask during bone conduction testing?

A
  • You always have to mask when testing BC

Exception: AC thresholds are = bilaterally and = unmasked BC thresholds

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12
Q

How can you determine how the minimum amount of masking is needed in the non-test ear for BC testing?

A

Min EML = AC threshold (NTE) + 10 dB + occlusion

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13
Q

How much is the occlusion effect (OE) with insert earphones?

A
  • OE is greater with shallow insertion

- OE is smaller with deep insertion

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14
Q

What is undermasking?

A

The tone that is presented to the test ear is picked up by the better cochlea

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15
Q

What is effective masking?

A

Masks the non-test ear from picking up the signal

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16
Q

What is overmasking?

A

There is so much masking noise that’s going to the non-test ear, which means that the test ear is picking up that masking noise.

17
Q

What is the Audiometric Weber?

A
  • Place the bone oscillator on the patient’s forehead
  • If the patient has a conductive hearing loss in one ear, and a sensorineural hearing loss in the other ear, they will hear the tone in the ear with the conductive hearing loss
  • If the patient has a bilateral conductive hearing loss, the patient will hear the tone in the center of the head (will not lateralize)