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Audiology > Audiometry > Flashcards

Audiometry Flashcards

1
Q

Why do screening tests?

A

Gateway into full tests and purchase of aids if HL present.

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2
Q

What is the procedure for a screening test?

A

Otoscopy
Instructions on screening test
1kHz at 55dBHL then 35 and 20
3kHz at 75, 55 then 35

Patient raises hand when hears tone and is scored on his many of the 6 tones they heard.

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3
Q

PTA v screening test - benefits of screening test?

A

PTA. screening test
Cost Cheap
Time. Quick
Trained. Objective test
Invasive. Minimally invasive

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4
Q

What is an audiometer?

A

An electrical instrument which measures deviation in hearing by measuring thresholds of pure tones at specific frequencies.

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5
Q

Describe calibration of an audiometer

A

A test to determine it’s true values, by comparison, with an accurate standard equipment which is then not interchangeable

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6
Q

What are the component parts of an audiometer and their purpose?

A

PURE TONE SIGNAL GENERATOR: generates single frequency sound signal at all frequencies

WHITE NOISE GENERATOR: used for masking

FREQUENCY SELECTOR: controls and selects frequency for both pure tone and white noise.

AMPLIFIER: increase signal intensity from generators

ATTENUATORS: control intensity sent to transducers

TRANSDUCERS: earphones TDH39 or insert earphones. Bone conduction by headband B71

ROCKER SWITCH: silent operation is a must.

TRANSDUCER SWITCH: switches between AC or BC test mode.

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7
Q

What do AC and BC test?

A

AC - test of total hearing mechanism as needs to be loud enough to stimulate BC in EAM s as well as outer and middle ear air conduction.

BC - delivered via mastoid bone and considered a test of COCHLEA function having missed out outer and middle ear.

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8
Q

What must be used for calibration?

A

Audiometer must be calibrated using earphone couplers.
6cc used as average volume of pinna, EAM and space within headphones is 6cc.

2cc if using earphone inserts - represents what is left in EAM when filled with inserts.

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9
Q

What are the 2 calibration tests, Who does them and when are they done?

A

Stage A - subjective test carried out by dispenser daily and weekly.

Stage B - objective test carried out annually by audiometer technicians.

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10
Q

What is the daily stage A calibration?

A

REBLESS

REsponse button
Battery
Leads
Earphones
Switches - secure? Lights? Work? Silent?
Sweeps:
Just audible 10dBHL all freq AC & BC
Louder level 60 AC & 40 BC
Masking. 60 all freq AC and BC

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11
Q

What is the weekly stage A calibration check?

A

CANT

Communication - circuits working?
Audiogram - self check for deviation
Noise - check for unwanted noise
Tension - in headgear AC&BC

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12
Q

What is stages are the annual calibration check what do they check?

A

Stage B & C

FAIRSHIT!

Frequency accuracy
Attenuator linearity
Intensity at 0dBHL
Rise and fall times
Spurious noise
Headband Tension
Intensity above 0dBHL
Tone purity

Audiometer and headphones calibrated as one soo will not be interchangeable with other kit.

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13
Q

What are the BSA recommended procedures for setting up for audiometry?

A

IN BRANCH:
Below 35dB ambient noise
Sound proof booth and room
Sound reducing screens

IN HOME:
Power required, good lighting
No trailing wires, good comms
Close windows, appliances
Remove visual distractions
Appropriate set up equipment/seating
Patient face visible
They cannot see screen/my hands

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14
Q

Explain the presentation/familiarisation tone of the PTA test.

A

Test stimuli between 1-3secs arrhythmic
Familiarisation: better ear first
Mid freq 1kHz (level most people will hear at)
1st time audible: normal hearing - 40dBHL or if has HL:
30 dBHL above estimated threshold
Not heard? Increase by 10dBHL
If reach 80 increase by 5dBHL

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15
Q

What do we do in PTA if patient reports tinnitus?

A

Request they ignore and respond to pure tone.
If unable to tell difference use warble tone at that frequency only and record such.

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16
Q

What is the BSA definition of threshold?

A

Threshold defined as the lowest level at which responses occur in at least half of a series of ascending trials with a minimum of 2 responses required at that level.

17
Q

What is an Audiogram?

A

It is a graph which plots hearing thresholds as deviations from normal hearing levels.

18
Q

What is an octave?

A

Unit corresponding to a doubling of a frequency ie
20-40Hz
40-80Hz
80-160Hz etc

19
Q

What are the initial medical questions prior to starting PTA?

A

Have you been exposed to any excessive noise in the last 24hrs?

Have you had any head operations resulting in implants?

Do you have a pacemaker fitted?

Do you experience tinnitus?

Which ear do you deem to be the better if any?

Please remove glasses, aids etc

20
Q

What are PTA patient instructions?

A

I am going to test your hearing by measuring the quietest sound you can hear.

When you hear a sound, press and hold the button for add king as you hear the sound. Release the button when you can no longer hear it.

Whatever the sound. No matter how faint or which ear, if you think you hear the sound press the button and hold until you can no longer hear it, then release the button.

If you wish me to stop at any time rate your hand.

Do you understand?

21
Q

What is the PTA test procedure?

A

Familiarisation tone @ 1kHz
2000, 4000, 8000, 500 and 250

Retest 1kHz to ensure patient understood. Retest must be within 5dB of original

At each frequency find the threshold.

Intermediate frequencies when required.

22
Q

What are the audiometry rise and fall times?

A

The audiometer output signal is not instant, signal rides until it hits a max and then falls off when switched off.

Incorrect Rise and fall times can affect the result.
If too slow: poor threshold as no maximum’ On effect’ of ear.
Too fast: overshoot, hard as a click - test compromised if patient reacts to click.

23
Q

At what point do we refer for a significant shift in audiometric results in comparison to the previous results?

A

When there is a 15dB or more difference at 2 or more frequencies AC or BC

24
Q

In what 3 ways can we stimulate the cochlea?

A

Direct skull vibration
Natural resonance frequency of the ossicular chain (approx 2hz)
Pseudo air conduction - the vibro tactile threshold above 2kHz ie can feel it rather than hear it

25
Q

What odd the vibro tactile threshold?

A

It is the response to the perception of vibrations through feeling rather than true hearing.
It varies with frequency:
25dB@250Hz
55dB@500Hz
70dB@1000Hz audiometer limit

26
Q

What are the limitations of the B71 headband?

A

Distortion occurs below 500Hz
Airborne sounds above 2000Hz (results in vibro tactile threshold)

Ambient noise below 35dB
Maximum output levels of audiometer
Headband tension

27
Q

What are the starting tone presentations for AC, BC and ULL’s?

A

AC 40dBHL for normal hearing or 30dBHL above estimated threshold of someone with a hearing loss

BC 10-15db above AC threshold of the same ear

ULL’s 60dBHL or there AC threshold whichever is the higher

28
Q

What are LDL and MCL?

A

Loudness discomfort level
Most comfortable level

29
Q

What are the limitations of an audiometer?

A

It’s subjective
Only a pure tone
Audiometer in dBHL but HA output in dBSPL.

30
Q

What are the contraindications of using an audiometer?

A

Tinnitus
Hyperacusis
Distress from noise

31
Q

What are pascals?

A

It is a measurement of pressure Pa

Quietest sound for humans is 0.00002Pa or 20 microPa

Loudest sound is 20,000,000 microPa or 20 pascals

32
Q

How do we convert pascal to dBSPL?

A

dBSPL = 20 x log pressure divided by reference pressure

Reference pressure is always 20

For example 200 microPa:
20 x log (200 divided by 20 = 10 count zeros therefore 1)
20 x 1 = 20dBSPL

33
Q

What is MAP and RETSPL?

A

Minimum audible pressure - how much sounds needed to be heard

Reference equivalent threshold sound pressure level (dBSPL) - all frequencies are different in terms of when we start to hear sound. So RETSPL creates 0 dBSPL soo we have a flatline reference point. Graph flipped upside down soo can now show a deterioration.
RETSPL at 1kHz is actually 7.5 rather than 0.

Audiology (15 decks)

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