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EduLink S

MultiFrequency

SmartLink SX

Importance of FM Systems

and Product Overview

Evert Dijkstra, Phonak Communications,Murten, Switzerland

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EduLink S

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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

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EduLink S

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Introduction

• Noise

• Reverberation

• Distance

Three factors deteriorate the Signal-to-Noise ratio and therefore the speech perception

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EduLink S

MultiFrequency

SmartLink SX

Noise

Many of our daily activities are happening in a noisy environment

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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

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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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Echo

All rooms cause echos; depending on building materials some more than others

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EduLink S

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Field Study Helfer & Wilber

Comparison scores for different ages

With S/R = 10 dB

Words with/without meanings

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EduLink S

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Meaningful Words

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Meaningless words

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EduLink S

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Distance

Distance (Meter)

80

70

60

50

40

dB

Noise floor

0 2 41 6

Recordings: (www.utdallas.edu/~thib)

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EduLink S

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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

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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

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SmartLink SX

Principle of FM

FM

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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

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EduLink S

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Settings for fieldstudy

SuperZoom (2 directional microphones)Zoom (1 directional microphone)Wide-Angle (1 omnidirectional microphone)TX3

Claro-FM

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EduLink S

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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

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EduLink S

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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