Objective Testing

Question 1

Under what age do we not use 226Hz tymps and why?

Answer 1

younger infants, under 6 months, have mass dominated systems for some frequencies

for these infants we use a 1000Hz tone
- but can’t get ECV with 1000Hz

also 1000Hz for screening reflex tone

    - looking for integrity of the 7th and 8th nerves and brain stem
    - would test if worried about neuropathy
    - problem with testing in neonates - high levels can stress children and make them cry
    - 1000Hz tone makes a curve upwards not downwards

Question 2

When would you do 1000Hz screening reflex on neonates?

Answer 2

Looking for integrity of the 7th, 8th nerves and brain stem

Worried about neuropathy

Question 3

Advantages and Disadvantages of TEOAEs

Answer 3

Advantages

   - fast obtain
   - 45dBnHL (80dBpeSPL) which is sensitive to pick up HL from 30dB

Disadvantages

   - Click stimulus not very frequency specific
   - High frequency components may be attenuated

Question 4

Avantages and Disadvantages of DPOAEs

Answer 4

Advantages

   - frequency specific
   - good for monitoring changes 
   - can be quick to obtain
   - can generate an input/output function

Disadvantages

   - use 65/55 dB stimuli and OAEs may be seen in even moderate HL
   - can take a long time to obtain
   - often cannot record DPs below 1000Hz due to noise

Question 5

What is a pass results for OAEs?

Answer 5

2/3 test frequencies

2,3 &4 kHz

Question 6

Is ABR a hearing test?

Answer 6

An ABR is a test of the function of the 8th nerve up to the point of the brainstem not a hearing test

Question 7

ABR recording parameters

Answer 7

Electrode placement

• • • high forehead (vertex not usually used because of the open fontanel)
• • • mastoids
• • • cheek (ground)

For screening ABR high forehead, nape, shoulder

Filter settings (30-1000Hz)

Recording window should be larger than with adults as the response latencies are longer than adult values (typically 15ms for click and 23ms for tone burst)

ABRs continue to mature until three years of age

less than 3KOhms impedance

Sleeping state; not effected by sedation or GA

1025sweeps for click

2000sweeps for tone-burst

Question 8

Differences between aims for adults ABR and infants

Answer 8

Main aim for adult is acoustic neuroma

• • • only use click
• • • only one stim presentation level
• • • only AC

Main for infant is thresholding

• • • click and toneburst
• • • multiple levels
• • • full AC and BC

Question 9

Click Evoked ABR

Answer 9

estimate of hearing in 2-4kHz region

easy to interpret

can be used in diagnosis of auditory neuropathy/dyssynchrony

use both condensation and rarefaction clicks to determine the presence of a cochlear microphonics

cannot be used when considering hearing aid fitting and parameters

Question 10

What do tone-burst evoked ABR do?

Answer 10

can give estimate of hearing thresholds 500, 1, 2, 4

can be used to determine if hearing aid fitting is warranted

can be adapted to use for hearing aid programming

BUT there is literature to suggest they can over estimate. Turns out it is more likely they underestimate by 10dB. Also ABR machines are limited to presentation levels of between 85-95dBnHL so difficult between severe and profound HL

Question 11

What are considerations for paediatric ABR?

Answer 11

Primary goal is threshold estimation and ANSD diagnosis

Repeatability

Limited time

Waveform morphology is unlike that of an adult

Question 12

ABR testing procedure

Answer 12

Begin testing at 60dB - audible but won’t wake them.

Order 2k, 500, 4k, 1k

Question 13

If you are concerned about ABR what to do?

Answer 13

If you get nothing for tone burst at 2kHz and get nothing, check straight away a click for cochlear microphonic

Include BOA in battery

Will have typs present, OAEs present, absent reflexes, no ABR wave 5 and cochlear microphonics

Question 14

When would you do ABR under sedation?

Answer 14

Concern for syndrome, meningitis

Question 15

Is ASSR a test of hearing?

Answer 15

ASSR is a test of sub cortical neural responses not a direct test of hearing

Question 16

Good things about ASSR

Answer 16

Quick to obtain responses

Frequency specific

Fourier and statistical techniques used to determine response presence/absence

Rance et al 1995 found ASSR thresholds match behavioural thresholds more closely for hearing imparied than normal hearing

Can test multiple frequencies at once

Can manipulate modulated signal

Can present stimuli of up to 120dBHL

Only really used when ABR has said that there is something more than a severe loss (because not great for people with normal/mild hearing)

Question 17

What modulation frequency do we use for infant ASSR?

Answer 17

70Hz and 90Hz as opposed to 40Hz

40Hz response affected by sleep because it is a cortical response. Would need subject to be still and awake which is rare for an infant

70Hz MLR response

90Hz - peripheral sensitivity
we test sleeping infant with 90Hz

Question 18

What are CAEPs and what do they test?

Answer 18

Cortical Auditory Evoked Potential

CAEPs are a way of evaluating higher cortical processing in response to auditory stimuli

They can be used to evaluate HA fittings in infants

Give an idea of CI effects

Question 19

CAEP stuff

Answer 19

Usually speech stimuli (ba ba ba) 1sec interstimulus interval

Need to be awake

Good corticals in ANS kids are more likely to do well with CIs

Wave response p1 (100ms stim onset) n1 (150ms) p2 (200ms) possible n2 (see mridula for actual numbers)