HAT 5 Feedback & Occlusion

Question 1

What do you look at first to resolve feedback or occlusion?

Answer 1

Non-electronic methods

Question 2

What are the symptoms of occlusion? (4)

Answer 2

Bunged up feeling
Own voice sounds weird
Loud noise you get internally
Sounds like head in a bucket

Question 3

What causes occlusion?

Answer 3

Low frequencies trapped in ear canal
Clients own voice (amplification)

Or both above

Question 4

What aids do not create occlusion?

Answer 4

IIC’s due to there position in canal

Question 5

What is the cure for occlusion? (2)

Answer 5

Add a vent
Decrease low frequency gain

Question 6

What are the benefits of venting? (4)

Answer 6

Reduction of the occlusion effect

Clearer and more natural speech and sound

Improved clarity in the background noise

Less upward spread of masking

Question 7

Name 2 types of vent

Answer 7

Parallel to souls tube in either ITE or BTE

Y venting - space restrictions (only in BTE mould)

Question 8

What vent size is used for a HF loss 0-10dBHL?

Answer 8

Large vent 3-4mm

Question 9

What vent size is used for a HF loss 11-40dBHL?

Answer 9

Medium 2mm

Question 10

What vent size is used for a HF loss of 41-60dBHL?

Answer 10

Small 1mm

Question 11

What vent size is used for a HF loss of 61dBHL+?

Answer 11

No vent

Question 12

What is a vent not used for? (2)

Answer 12

To allow discharge to drain
To ventilate ear

Question 13

What is feedback?

Answer 13

HF amplified sound that leaks out of ear canal and is picked up again by microphone

This signal adds in phase with incoming signal and may be amplified over & over resulting in oscillation (whistling)

Question 14

What are the standard solutions for feedback? (3)

Answer 14

Plug ear tightly
Decrease high frequency amplification
Turn down the volume