Basichearingaidtech Day2 Delta.ppt

Hearing aids
Types
Settings
Basic hearing aid technology
Design
Linear/nonlinear
Analogue/digital
Interface
Adjustment/programming
March 2002
1
Module 5
Illustration: ”A sense of hearing”
Standard types of hearing aid
In the Ear or ITE aids
Concha
Canal
CIC (Completely in the Canal)
Behind the Ear or BTE aids
March 2002
2
Module 5
Behind the ear aids: advantages/disadvantages
Advantages
Can be adjusted in the open ear
Directional microphone
Relatively invisible
Room for telecoil or FM
Greater amplification
Room for large battery
Disadvantages
Plastic tube affects sound quality
Microphone not in the ear
Cosmetic drawbacks
March 2002
3
Module 5
In the ear aids: advantages/disadvantages
Advantages
Acoustically superior
Directional microphone
Relatively invisible
Disadvantages
Problems with acoustic promise solutions because of size
Damage from ingress of ear wax etc.
Small batteries with short service life
Limited amplification magnitude
Small control buttons
Often without telecoil or FM
March 2002
4
Module 5
Bone-anchored aids
Illustration: ”A sense of hearing”; ”Hearing and technical measures”
Special types of hearing aid
CROS – BICROS
((Bilateral) Contralateral Routing of Signal)
Tactile “hearing aids”
Spectacle hearing aid
March 2002
5
Module 5
Advantages
BW aids provide the greatest possible amplification
Limited feedback problems
Large control buttons
Large batteries
Room for technological features
Body-worn hearing aids: advantages/disadvantages
Disadvantages
Visible
Transducer lead
Location of microphone
Microphone noise from clothing
March 2002
6
Module 5
Special types of hearing aid
Illustration: ”A sense of hearing”
Cochlear implant
22 electrodes
March 2002
7
Module 5
Source: Oticon
Basic hearing aid design
March 2002
8
Module 5
Basic hearing aid design
Sound waves
Loop System
T-coil
Microphone
Amplifier
Telephone, loudspeaker
Battery
Reciever
M –T switch
DSP
March 2002
9
Module 5
Micropho