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Amplification 2 > Verification: Ear Level Calibration and Probes > Flashcards

Verification: Ear Level Calibration and Probes Flashcards

1
Q

Does each REM system have an external loudspeaker capable of generating a variety of input signals?

A

Yes

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2
Q

What is the ear-level probe module?

A

It connects the patient to the REM system

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3
Q

What does the ear-level probe module consist of?

A

Reference microphone: to monitor and calibrate the sound field speaker output, maintaining the desired signal intensity at the measurement point
Retention cord: to stabilize and maintain the reference microphone’s position
Probe tube: to measure the intensity of the signal arriving to the TM
Probe microphone: collects and measures sound from the probe tube attached to it

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4
Q

Can you view data in a single view or dual view?

A

Yes

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5
Q

What is the best way to view real ear data clinically?

A

Dual view, to ensure that real ear aided responses are within 15 dB
The aided output must be w/I 15 dB to achieve binaural benefit

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6
Q

What is a type 1 test signal?

A

Pure tone signal swept over a variety of frequencies

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7
Q

What is the benefit of a type 1 signal?

A

Drive a higher output than speech signals
Used to accurately measure maximum loudness when verifying MPO

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8
Q

What are the type 1 signal limitations?

A

Does not show affect of compression or channel interactions on the output signal
Digital feedback suppression signals attenuate Type I signals when its activated (output you’re measuring is different than what the patient is hearing)

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9
Q

What are type II signals?

A

Complex
Speech-like signals
Broadband signal consisting of random frequencies occurring at different intensities

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10
Q

What is the benefit of using type II signals?

A

It’s unpredictable moment to moment
Amplitude changes mimic speech

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11
Q

What is a type II signal limitation?

A

Rapid gain changes may not truly show a device’s response to different spectral shapes in the succeeding sounds

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12
Q

What are the standardized type II speech signals?

A

Speechmap - speech signals filtered to provide the long-term average speech spectrum (LTASS) (carrot)
ISTS - International Speech Test Signal: 6 female talkers reading the same passage in American English, Arabic, Chinese, French, German and Spanish
ICRA - International Collegium for Rehabilitative Audiolog: distorted speech signal is a recording of an English-speaking talker that has been digitally modified to make the speech largely unintelligible

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13
Q

What is required of the standardized type II speech signals?

A

Provide repeatable, consistent signals to verify a device’s ability to meet prescriptive targets for output and frequency response
Contain all sounds within the speech spectrum within a 10 second passage

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14
Q

How are non-standardized signals used during programming?

A

Helpful in counseling, but cannot be used for prescriptive fittings
Signal limitations: signals lack standardized repeatability
Speech- female
Speech- child
Speech- live

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15
Q

What is speech-live?

A

Measures the LTASS and speech envelope of any audible signal over 10 seconds
Use: probe microphone acts as a spectrum analyzer and “test signal” is typically communication partner’s voice

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16
Q

What is the measured speech envelope?

A

A measurement showing the dynamic range of the speech signal arriving to the tympanic membrane
The difference between the valleys (softest signal) and peaks (loudest signal) of speech is ~30dB SPL
Because the spectrum of a speech signal varies with time, it is necessary to average measurements over several seconds to obtain a stable, repeatable result (LTASS)

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17
Q

When is SII maximized?

A

When the entire speech signal is above threshold

18
Q

What is the LTASS?

A

A frequency-dependent measure of time averaged sound pressure level of speech

19
Q

Will LTASS change with varying vocal effort, mic position, and language?

A

Yes
Vocal effort primarily influences the mid-frequency LTASS average
Microphones azimuthal position strongly influences the high-frequency LTASS average
Tonal languages influences low frequency LTASS average

20
Q

How is the LTASS calculated?

A

By averaging a measured signal for 10 seconds

21
Q

Do speech signals with different intensities have a different LTASS?

A

Yes

22
Q

Will an individuals LTASS differ from the LTASS of a standardized signal?

A

Yes

23
Q

How much louder are speech envelope peaks than the average LTASS?

A

12 dB

24
Q

How much softer are speech envelope valleys than the average LTASS?

A

18 dB

25
Q

What is the substitution method of sound field equalization?

A

A sound level measurement microphone is placed at subject’s position
Calibration is stored and used as a reference point

26
Q

What are the limitations of the substitution method of sound field equalization?

A

Absence of subject’s head/body reduces precision
Changes in location/ movement of subject impacts results
If patient moves from reference point (slouching, moving the chair, etc.) it is no longer calibrated

27
Q

What are the two kinds of modified pressure methods?

A

Modified pressure using concurrent equalization
Modified pressure using stored equalization

28
Q

What is the modified pressure using concurrent equalization method?

A

The reference mic constantly monitors the test signal throughout testing to equalize & adjust signal intensity
Recalibration occurs automatically
The calibration signal replays every 10 seconds throughout measurement process

29
Q

What is the modified pressure using stored equalization method?

A

The probe is calibrated one time on the patient’s ear, and it stored for the fitting process
This method is used when amplified sound can leak out of open domes and interact with reference microphone

30
Q

What is a limitation of the modified pressure using stored equalization method?

A

Head movement during measurement can impact the final recording

31
Q

Why is the stored equalization method used?

A

To avoid reference mic contamination

32
Q

What is reference mic contamination?

A

Occurs when the amplified output escapes the ear canal through open domes
The reference mic measures and reacts to the intensity of the hearing aids output signal lowering the intensity of the speaker’s input signal
Tricked into raising the gain unnecessarily

33
Q

What are the two methods for insertion/landmark?

A

Intertragal notch and anterior notch

34
Q

How do you do the acoustic method of probe tube insertion?

A

Present a 65 dB SPL pink noise signal while inserting probe tube
Gently insert the probe tube while keeping an eye on the high frequency notch
The probe is w/i 5mm of the TN when the notch is no longer dragging the gain curve down in the high-frequencies
Move the marker into position

35
Q

What is the constant depth method of probe tube insertion?

A

Move the probe tube marker to a premeasured position on the probe tube
Distance from intertragal notch to TM is about:
Male: ~30 mm
Female: ~28 mm
Pediatric: move marker to ~20-25 mm

36
Q

How do you perform audioscan calibration?

A

Place tip of probe directly over reference mic
The modified pressure concurrent equalization calibration signal arrives simultaneously to the probe tip and reference mic during
Therefore, the “distance” b/w the reference mic and probe tube tip becomes acoustically invisible

37
Q

What is the recommended method for placing a probe tube?

A

Combine the constant depth and acoustic insertion methods

38
Q

What must the probe tip location be?

A

Must be within 5 mm of the TM to provide an accurate assessment of SPL across the frequency range, particularly in the higher frequencies
Placement more than 5 mm from the TM creates acoustic nulls resulting from standing waves (trick you into believing the high frequency output is lower than the actual output of the device)

39
Q

What is the geometric position method?

A

Typically used when patient is squirmy/not cooperative
Probe tube placed along the outer ridge of the intertragal notch of device
Probe tip extends 3- 5 mm beyond the tip of the earmold (close enough)
Mark the probe tube length

40
Q

Is there a verifit 2 probe tube guide?

A

Yes
Helps you place the probe tube at the appropriate position
Still need to know the other methods because not everyone has the verifit 2

Amplification 2 (13 decks)

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