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1
EduLink S
MultiFrequency
SmartLink SX
Importance of FM Systems
and Product Overview
Evert Dijkstra, Phonak Communications,Murten, Switzerland
2
EduLink S
MultiFrequency
SmartLink SX
Outline
Introduction FM systems
State-of-the art FM systems for hearing impaired children, adults, and CI recipients
State-of-the art FM systems for children with Auditory Processing Disorders, Attention Deficit and Learning Disabilities
Conclusions
3
EduLink S
MultiFrequency
SmartLink SX
Introduction
• Noise
• Reverberation
• Distance
Three factors deteriorate the Signal-to-Noise ratio and therefore the speech perception
4
EduLink S
MultiFrequency
SmartLink SX
Noise
Many of our daily activities are happening in a noisy environment
5
EduLink S
MultiFrequency
SmartLink SX
HL and additionally required SNR
0 5 10 15 20
20
30
40
50
60
70
80
90
Necessary SNRfor 50% recognition of sentences (adults)
Avera
ge h
eari
ng loss
in
dB
Avera
ge h
eari
ng loss
in
dB
Signal-to-Noise ratio in dB (Ref.: normal Signal-to-Noise ratio in dB (Ref.: normal hearing)hearing)
Killion, 1997
6
EduLink S
MultiFrequency
SmartLink SX
Difference in SNR between children and adults
Curves compare adult and infant sound discrimination in noise - normal hearing
Children are at a greater disadvantage than adults
Noise has greatest impact on children during the period of language acquisition
Infants 8-11 months Adults
Nozza et al., 1990
1.0
0.9
0.8
0.7
0.6
0.5
0.4
Signal-to-Noise Ratio (dB)
Pro
port
ion c
orr
ect
-16 -8 0 8 16 24
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EduLink S
MultiFrequency
SmartLink SX
Echo
All rooms cause echos; depending on building materials some more than others
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EduLink S
MultiFrequency
SmartLink SX
Field Study Helfer & Wilber
Comparison scores for different ages
With S/R = 10 dB
Words with/without meanings
9
EduLink S
MultiFrequency
SmartLink SX
Meaningful Words
10
EduLink S
MultiFrequency
SmartLink SX
Meaningless words
11
EduLink S
MultiFrequency
SmartLink SX
Distance
Distance (Meter)
80
70
60
50
40
dB
Noise floor
0 2 41 6
Recordings: (www.utdallas.edu/~thib)
12
EduLink S
MultiFrequency
SmartLink SX
Effect of distance on normal hearing children and adults
All children are at a disadvantage when listening to a distant speaker or in background noise
Hearing impaired children have an even greater disadvantage in these environments
Adapted from Johnson 1996
Age Group
Word recognition up-close in quiet
(1.8 m)
Word recognition with distance &noise
(7 m)
4 years5 years6 yearsAdult
88.3%94.3%98%
99.3% 97.0%
86.7%84%
67%
Normal hearing children and adults
13
EduLink S
MultiFrequency
SmartLink SX
Available technologies?
Key Question: Are there technologies that can simultaneously
restore the required SNR, avoid the impact of echo’s and overcome the distance ?
Answer today: Only one, I.e. FM technology
Answer tomorrow: Most likely only one, I.e. FM technology
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EduLink S
MultiFrequency
SmartLink SX
Principle of FM
FM
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EduLink S
MultiFrequency
SmartLink SX
0°
45°
135°225°
315°
TX3
1 m
*
*
HINT Sentences
Correlated HINT Noise
1 meter (39“) Loudspeakers to center of head.
7.6 cm (3“) Loudspeaker toTX3 Transmitter
Fieldstudy with 48 adults
Source: Valente, 2002
16
EduLink S
MultiFrequency
SmartLink SX
Settings for fieldstudy
SuperZoom (2 directional microphones)Zoom (1 directional microphone)Wide-Angle (1 omnidirectional microphone)TX3
Claro-FM
17
EduLink S
MultiFrequency
SmartLink SX
8.6 3.1 -0.8
-14.6 -18.9
-5
-20
-15
-10
-5
0
5
10
Mea
n R
TS
(dB
)
Una
ided
Om
ni
Dua
l
FM
-M
FM
-B
Nor
mal
Listening Conditions
5.9 2.3 1.8 6.5 3.2 2.1 (SD)
4.3 dB
Source: Valente, 2002
18
EduLink S
MultiFrequency
SmartLink SX
Evolution of FM receivers
Body-worn MicroLink
MLx
Focus:Robustness
Focus:Miniaturization
Focus:Standardization
Focus:Flexibility
1997 1999 2003
MLxS iLink
Focus:Integration
2005