Cochlear Nucleus 8 Manual page 24

Problem Possible cause
High distortion Wax is blocking a
filter
Hybrid receiver is
broken
Occlusion The dome vent is
('Head in a blocked
bucket'
Dome vent is too
sensation)
small
Dome fit is too tight
Intermittent Wax or moisture
contact,
crackling sound
Loose connection
point at the earhook
Sound processor
fault
20
Test / resolution
1. Replace the dome (with its built-in wax filter).
2. Check the wax filter on the speaker unit and
replace if necessary.
Educate the recipient to do this regularly.
Check the Hybrid receiver using a listening test, and
replace it if required.
If the test is not conclusive, reproduce the 'Total
harmonic distortion' measurement described in the
Data Sheet supplied with this guide and check
against the outlined limits.
Check the vent for obstruction. Replace the dome if
necessary.
Pull the speaker unit slightly out of the ear. If this
makes the sound quality improve, change to a dome
with a larger vent size.
Change to a smaller dome.
1. Wipe the system dry.
2. Replace the dome (with its built-in wax filter).
3. Check the wax filter on the speaker unit and
replace if necessary.
Educate the recipient to do this regularly.
Perform a listening test using a Stetoclip while
carefully moving all parts of the Hybrid system in
turn. Replace the Hybrid receiver if necessary.
Perform a listening test using a Stetoclip. If this
shows a problem, send the sound processor for
repair.
Hybrid Mode Professionals Guide