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Hearing Loop System

Hearing Loop System. Conny Andersson Standards IEC 60118-4 Sound examples. Conny.Andersson@edin.se. Hearing Instrument. Reverberation time = 2 sec Speaker @ 4m distance Babble noise (other speakers) Output from a Hearing Aid (artificial ear). International Standards, IEC.

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Hearing Loop System

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  1. Hearing Loop System Conny Andersson Standards IEC 60118-4 Sound examples Conny.Andersson@edin.se

  2. Hearing Instrument • Reverberation time = 2 sec • Speaker @ 4m distance • Babble noise (other speakers) • Output from a Hearing Aid (artificial ear)

  3. International Standards, IEC American National Standard Institute • Harmonized world wide • Hearing Instrument (HI) • Hearing Loop system International Electrotechnical Commission

  4. IEC 60118-4, “Loop Standard” Magnetic Field Strength = 400mA/m. Relates directly to the output level of the Hearing Instrument Coverage area/space (sitting and standing), +-3dB

  5. Field distribution – level/coverage Level: 400mA/m Fluctuation: within +-3dB

  6. Field distribution – level/coverage (This slide contains the notes for the previous slide)

  7. Frequency response High frequency damping or metal loss is increased as a function of the distance to the loop wire. It cannot be fully compensated by the loop amplifier. It can be compensated by the loop figuration.

  8. No frequency limitations 100 200 300 500 1k 2k 3k 5k Hz 9 seconds

  9. High frequency loss from 1kHz 100 200 300 500 1k 2k 3k 5k Hz 9 seconds

  10. High frequency loss from 500Hz 100 200 300 500 1k 2k 3k 5k Hz 9 seconds

  11. No frequency limitations 100 200 300 500 1k 2k 3k 5k Hz 9 seconds

  12. Surrounding noise (hum) Background noise (hum) from electrical appliances creates noise directly into the Hearing Instrument Standard: less than -32dBA (-47dBA) Level, Magnetic Field Strength 400mA/m

  13. Background Noise (hum) • High background noise: -12dBA • Tiresome

  14. Adding a weak amplifier • Low Field Strength: -12dB (100mA/m) • Very low speech intelligibility

  15. Stronger amplifier – same noise • Accepted Field Strength: 0dB (400mA/m) • Enhanced speech intelligibility

  16. Approved field strength– same noise • Accepted Field Strength: +3dB (560mA/m) • Further enhanced speech intelligibility

  17. Complies to standard • Correct Field Strength: 0dB (400mA/m) • Noise complies to the standard, -32dBA

  18. High quality Loop System • High Field Strength: +3dB (560mA/m) • Noise complies to -47dBA

  19. Conclusions of sound examples • Systems that sounds “noisy” is often a reflection of a weak hearing loop amplifier. • Loop systems could often easily be updated to comply with the level requirements (with increased Signal to Noise ratio and speech intelligibility).

  20. Conclusion and advise • Follow the international standard • Do not trust the manufacturers coverage area as they are highly overstated for practical installations. Trust real measurements. • A hearing instrument cannot be used to certify a hearing loop system.

  21. Thank you for your attention! Conny.Andersson@edin.se

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