Usu Comd 3700 Lesson 8 Exam 2

Front 1

What is the first step in clinical masking?

Back 1

Explain to the patient exactly what is going to happen and how they are to respond.

If not properly counseled, the patient will respond to the masking noise rather than the stimulus.

Front 2

When masking, what do you need to make sure to tell the patient?

Back 2

They should respond only when they hear the tone in addition to the noise - not the noise itself.

Front 3

What kind of noise should be used to keep the NTE busy so that it will not respond to the stimulus?

Back 3

It depends on the signal being masked.

Front 4

What is white noise?

Back 4

A broadband or wideband noise. All frequencies are covered with equal amounts of energy for each frequency.

Front 5

Why is white noise not often used in audiometric testing?

Back 5

Listening to the noise is fatiguing for any length of time. It is not as efficient in the lower frequencies as it is in the higher frequencies because of the upward spread of masking. It is both inefficient and unnecessarily loud.

Front 6

What is narrow band noise?

Back 6

Also known as NBN. NBN consist of a narrow range of frequencies of equal intensity.

Front 7

What are noise bands?

Back 7

They are components of noise coming off of the individual noise frequencies. They are identified by their central frequency.

Front 8

How is NBN used for masking?

Back 8

If testing 500 Hz tones, you would only need to use the cone of NBN for 500 Hz. If testing 2000 Hz, we need to change the corresponding NBN. Each time the frequency is changed, the NBN is also changed. This is done automatically on a diagnostic audiometer.

Front 9

Why is NBN preferred to white noise in masking?

Back 9

NBN is more efficient, effective and easily tolerated than white noise for pure tones.

Front 10

What are some other masking noises used for speech tests?

Back 10

Pink Noise, Speech Shaped Noise and Multitalker babble

Front 11

What is effective masking (EM)?

Back 11

It eliminates crossover from occurring. EM determines how much noise is appropriate to "cover up" or "keep busy" the better ear or NTE from taking part in the test.

Front 12

What is undermasking?

Back 12

This occurs when the masking noise presented to the better or NTE is not loud enough to eliminate crossover or Interaural Attenuation.

Front 13

Does undermasking occur more often in air conduction or bone conduction testing?

Back 13

Air conduction testing.

Front 14

What is overmasking?

Back 14

The condition when the noise presented to the NTE is intense enough to cross over to the TE and mask it.

Front 15

How do you know if overmasking is occurring?

Back 15

When each 10 dB increase in masking shifts the hearing threshold 10 dB or more above the plateau.

Front 16

Does overmasking occur more in air conduction or bone conduction testing?

Back 16

bone conduction

Front 17

What are the results when using undermasking or overmasking?

Back 17

Undermasking allows a false, better hearing threshold, while overmasking drives the true threshold lower.

Front 18

When would you use a wide band masking noise?

Back 18

If the signal has a wide spectrum (Speech or Clicks) then the masking noises must also have a wide spectrum.

Front 19

What are the different masking methods for air conduction?

Back 19

1. Shotgun method
2. Minimum Noise Method
3. Maximum Noise Method
4. Plateau Method
5. Step Masking Method

Front 20

What happens in the Plateau Method?

Back 20

The non-test ear is masked by progressively greater amounts of sound until the threshold of the test ear does not continue to increase. This indicates the "true" threshold of the test ear and masking may be discontinued.

Front 21

What is another name for the Plateau Method?

Back 21

The Threshold Shift Method (Hood, 1960).

Front 22

Define plateau.

Back 22

The plateau is a range of masking levels in which there is no increase in threshold of the TE. In this method, 5 or 10 dB steps at a time are used. When an adequate level of masking has been reached, there are generally several successive levels of masking that yield the same PT threshold in the TE.

Front 23

How many levels are needed to establish a plateau?

Back 23

Most audiologists use 3 consecutive masked levels (5 or 10 dB steps) with the same response to be a threshold.I

If you use 10 dB steps, sometimes only 2 consecutive masked levels are taken to avoid overmasking, but if you use 5 dB steps, you have to establish 3 consecutive masked levels.

Front 24

What is the range of effective masking?

Back 24

the width of the plateau.

Front 25

What are the procedure to the Plateau Method for air conduction testing.

Back 25

1. obtain an record the AC threshold of the TE unmasked.
2. compare the AC threshold of the TE with AC and BC thresholds of NTE to determine if masking is needed (Is there a difference of 40 dB or greater using supra aural headphones or 70 dB or greater using insert earphones?)

Front 26

Procedures for PM for AC testing (cont.)

Back 26

3. Select the initial amount of masking (IM) using narrow band noise on the audiometer for the NTE.
4. IM = AC (NTE) + 10 dB EML (Note: some audiologists use 5 dB or 15 dB effective masking level (EML)).

Front 27

Procedures for PM for AC testing (cont.)

Back 27

5, Reestablish threshold in the TE with this initial amount of masking in the NTE.
6. Each time the patient responds to the PT signal presented to the TE, increase masking noise in the NTE by 10 dB.

Front 28

Procedures for PM for AC testing (cont.)

Back 28

7. Each time the patient does not respond to the PT signal in the TE, increase the tone in the TE in 5 dB steps until the patient responds again.
8. Continue the procedure until the masking noise can be increased over a 30 dB interval (3 consecutive 10 dB steps) without producing a shift in the threshold level of the TE.
9. This is the "Plateau" and the AC pure tone intensity level you reached is the actual threshold of the TE.

Front 29

How do you place the earphones delivering the masking tone on the patient when doing bone conduction testing?

Back 29

The TE must not be occluded in any way with the earphone. The earphone should be placed on the head of the patient, but not over the ear. Be sure to tell the patient that the positioning is correct, or they may try to put the earphone over their ear.

Front 30

How does the occlusion effect come into play with bone conduction testing?

Back 30

Because the earphone delivering the masking is placed over the NTE, the occlusion effect may be created in that ear. The occlusion effect may cause BC thresholds to shift once headphones are placed on the head.

Front 31

What are the Plateau Method procedures for Bone Conduction?

Back 31

1. obtain and record the BC threshold of the TE unmasked and unoccluded.
2. compare the AC thresholds with the BC thresholds (ABG) to determine if masking is needed. (Is there a difference of 10 dB or more?)

Front 32

What are the Plateau Method procedures for Bone Conduction (cont.)?

Back 32

3. select the initial amount of masking (IM) for the NTE using NBN. (IM = AC (nte) + 10 dB EML + OE) (OE = Add an additional 15 dB at 250 Hz and 500 Hz and 10 dB at 1000 Hz)
4. Reestablish threshold in the TE with this initial amount of masking in the NTE.

Front 33

What are the Plateau Method procedures for Bone Conduction (cont.)?

Back 33

5. Each time the patient responds to the PT signal presented to the TE, increase masking noise in the NTE by 10 dB.
6. Each time the patient does not respond to the PT signal in the TE, increase the tone in the TE in 5 dB steps until the patient responds again.

Front 34

What are the Plateau Method procedures for Bone Conduction (cont.)?

Back 34

7. Continue the procedure until the masking noise can be increased over a 30 dB interval (3 consecutive 10 dB steps) without producing a shift in the threshold level of the TE.
8. This is the "Plateau" and the BC pure tone intensity level you reached is the actual threshold of the TE.

Front 35

What are the air conduction symbols used to plot thresholds on the audiogram?

Back 35

Right ear unmasked: O (red)
Left ear unmasked: X (blue)
Right ear masked: red triangle
Left ear masked: blue square

Front 36

What are the bone conduction symbols used to plot thresholds on the audiogram?

Back 36

Right ear unmasked: < (red)
Left ear unmasked: > (blue)
Right ear masked: [ (red)
Left ear masked: ] (blue)

Front 37

T/F: You should keep all markings (unmasked and masked) on the audiogram.

Back 37

False. It becomes too cluttered.

Front 38

Rule of Masking:

Back 38

When in doubt, mask.

It is better to mask and find out that it was not required. Test results obtained without masking when there is a need for masking, result in improper test results. Masking is time consuming and add several steps to the test procedure, so it is important to understand the rules of when to mask.