Pure tone audiometry and tympanometry

Question 1

What is pure tone audiometry?

Answer 1

This is a hearing test that measures a persons ability to register different sounds, pitches or frequencies

Question 2

Where is pure tone audiometry carried out?

Answer 2

This is carried out in a soundproof room that meets nationally recognised criteria

Question 3

How are audiometers calibrated?

Answer 3

Audiometers are calibrated to measure air conduction thresholds between 125 and 8,000 Hz and bone conduction thresholds between 250-6000Hz

And are calibrated to measure maximum air conduction thresholds of 120dB and bone conduction of around 50dB lower than this value

Question 4

What is meant by a pure tone?

Answer 4

Pure tones are the simplest of all sounds

They have a specific, single frequency, amplitude, phase and duration

Question 5

What is the unit for pure tone amplitude?

Answer 5

decibels

Question 6

What are the 3 main transducers used to present pure tones to patients?

Answer 6

• Headphones
• Insert earphones
• Bone conduction

Question 7

How will adults usually register a response to a sound in pure tone audiometry?

Answer 7

Pressing buttons

Question 8

How will children usually register a sound in pure tone audiometry?

Answer 8

Play items such as dropping coins into a piggy bank

Question 9

How is air conduction tested in pure tone audiometry?

Answer 9

• Assessed using headphones or insert earphones
• Assesses the entire auditory pathway

Question 10

How is bone conduction tested in pure tone audiometry?

Answer 10

• Assessed using a bone conductor
• Bypasses the external and middle ear and stimulates the inner ear

Question 11

What decibel level of hearing loss is classified as mild?

Answer 11

20 - 40 dB

Question 12

What decibel level of hearing loss is classified as moderate?

Answer 12

41 - 70dB

Question 13

What decibel level of hearing loss is classified as severe?

Answer 13

71 - 95 dB

Question 14

What decibel level of hearing loss is classified as profound?

Answer 14

> 95 dB

Question 15

How are results of pure tone audiometry presented?

Answer 15

Audiogram

Question 16

Describe the layout of an audiogram axis

Answer 16

Question 17

What does O on an audiogram mean?

Answer 17

Air conduction right ear

Question 18

What does an X on audiogram mean?

Answer 18

Air conduction left ear

Question 19

What does a ∆ on audiogram mean?

Answer 19

Bone conduction

Question 20

What is meant by masking in pure tone audiometry?

Answer 20

Sometimes, if there is a vast difference between the hearing ability of the ears, the good ear can pick up sounds and the brain thinks that the bad ear can hear them

Narrow band masking can be used by playing a masking noise to the good ear

This should be added after an initial test with the test being repeated

The masking sound should then be increased by 10dB and retested to find a new masking threshold 3 more times

Question 21

What are the masking symbols used in pure tone audiometry?

Answer 21

Question 22

What are the features of sensorineural hearing loss on audiogram?

Answer 22

• No significant bone gap
• High pitched sounds affected first

Question 23

What causes permanent sensorineural hearing loss?

Answer 23

Damage to the hair cells within the cochlear, or damage to the cochlear nerves

Question 24

What type of hearing loss is shown?

Answer 24

Sensorineural - Affects air conduction and bone conduction so both follow same pathway. Higher pitched sounds heard first, so hairs affected more by sound

Question 25

What are the features of conductive hearing loss on audiometry?

Answer 25

• Significant air-bone gap

Question 26

What is shown?

Answer 26

Conductive hearing loss

Question 27

What are the features of mixed hearing loss on audiogram?

Answer 27

• Significant air-bone gap in parts
• No air-bone gap in others

Question 28

What are some causes of mixed hearing loss?

Answer 28

• Genetic factors
• Birth defects
• Infections
• Tumours or masses
• Head injuries

Question 29

What is shown?

Answer 29

Mixed hearing loss

Question 30

What is shown?

Answer 30

Mixed hearing loss

Question 31

What is tympanometry?

Answer 31

This is an examination used to test the condition of the middle ear, mobility of the eardrum and the conduction of the ossicular chain by creating variations of pressure in the ear canal

Question 32

What is shown on a type A tympanogram?

Answer 32

Normal eustachian tube function. Eardrum is moving normally with a pressure change.

Question 33

What is shown on a type B tympanogram?

Answer 33

This shows that something is restricting ear drum movement, most likely fluid in glue ear (Ossification would show type As, not B)

Question 34

What is shown on a type C tympanogram?

Answer 34

The drum is moving but something is retracting it (Negative pressure from the eustachian tube) - This is reversed by the Valsalva move

Question 35

What is shown by a type As tympanogram?

Answer 35

Ossification of the tympanic membrane

Question 36

What is shown by a type Ad tympanogram?

Answer 36

When a patient has a perforated eardrum, the measured canal volume may be quite large, as the measurement is going beyond the area between probe and drum and now into the middle ear via the perforation. If the ossicular chain is disarticulated, the drum may become flaccid (Type Ad-deep tymp).