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Importance of FM Systems and Product Overview

Importance of FM Systems and Product Overview. Evert Dijkstra, Phonak Communications, Murten, Switzerland. Outline. Introduction FM systems State-of-the art FM systems for hearing impaired children, adults, and CI recipients

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Importance of FM Systems and Product Overview

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  1. Importance of FM Systems and Product Overview Evert Dijkstra, Phonak Communications, Murten, Switzerland

  2. 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. Introduction Three factors deteriorate the Signal-to-Noise ratio and therefore the speech perception • Noise • Reverberation • Distance

  4. Noise Many of our daily activities are happening in a noisy environment

  5. HL and additionally required SNR Necessary SNR for 50% recognition of sentences (adults) Average hearing loss in dB Killion, 1997 Signal-to-Noise ratio in dB (Ref.: normal hearing)

  6. Infants 8-11 months Difference in SNR between children and adults 1.0 0.9 0.8 0.7 0.6 0.5 0.4 • 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 Proportion correct -16 -8 0 8 16 24 Signal-to-Noise Ratio (dB) Adults Nozza et al., 1990

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

  8. Field Study Helfer & Wilber • Comparison scores for different ages • With S/R = 10 dB • Words with/without meanings

  9. Meaningful Words

  10. Meaningless words

  11. Recordings: (www.utdallas.edu/~thib) Distance dB 80 70 60 50 40 Noise floor 4 6 0 2 1 Distance (Meter)

  12. Effect of distance on normal hearing children and adults 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 Word recognition up-close in quiet (1.8 m) Age Group Word recognition with distance &noise (7 m) 67% 4 years 88.3% 5 years 94.3% 84% 6 years 98% 86.7% Adult 99.3% 97.0% Adapted from Johnson 1996

  13. 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

  14. Principle of FM FM

  15. Fieldstudy with 48 adults Source: Valente, 2002

  16. Settings for fieldstudy SuperZoom (2 directional microphones) Zoom (1 directional microphone) Wide-Angle (1 omnidirectional microphone) TX3 Claro-FM

  17. 5.9 2.3 1.8 6.5 3.2 2.1 (SD) 4.3 dB Source: Valente, 2002

  18. MicroLink MLx Evolution of FM receivers Focus:Integration Focus:Flexibility Focus:Standardization Focus:Miniaturization Focus:Robustness MLxS Body-worn iLink 1997 1999 2003 2005

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