1. www.univ ox.eu Conny Andersson IEC 60118-4 Conny.Andersson@edin.se

2. www.univ ox.eu Receiver = T-coil in Hearing Instrument (HI) No current consumption Transmitter = Loop Amplifier and Loop World Wide Standard Receiver = T-coil in Hearing Instrument (HI) No current consumption Transmitter = Loop Amplifier and Loop World Wide Standard

3. www.univ ox.eu InputInput Acoustic Output switchswitch M M T T HearingInstrumentHearingInstrument Loop Level: Fixed @ 400mA/m for all signals Loop Level: Fixed @ 400mA/m for all signals Speech level=70dB @1m distance Speech level=70dB @1m distance 130dB130dB Gain +60dB Coil Sensitivity 130dB130dB Same output level for M and T-position

4. www.univ ox.eu Switching between M and T will give approximately the same output level It could be stated differently: 0dB difference between M and T-position Related to acoustic level: The acoustic output is the same for T and M-position with a 70dB acoustical input signal Switching between M and T will give approximately the same output level It could be stated differently: 0dB difference between M and T-position Related to acoustic level: The acoustic output is the same for T and M-position with a 70dB acoustical input signal

5. www.univ ox.eu Hearing Instrument (HI) Hearing Instrument (HI) Many parameters are fitted for the individual. Can not be standardized Many parameters are fitted for the individual. Can not be standardized Hearing Loop system Hearing Loop system All parameters are standardized All parameters are standardized Hearing Instrument (HI) Hearing Instrument (HI) Many parameters are fitted for the individual. Can not be standardized Many parameters are fitted for the individual. Can not be standardized Hearing Loop system Hearing Loop system All parameters are standardized All parameters are standardized International Electrotechnical Commission

6. www.univ ox.eu American National Standard Institute has many abbreviations for T-coil functions 3.4 Terms relating to measurements with inductive inputs 3.4.1 high frequency average SPL for an inductive telephone simulator (HFA-SPLITS). The high frequency average of the SPLITS levels (see Clause 3.4.5). The abbreviation for this term is HFASPLITS. 3.4.2 high frequency average SPL in a vertical magnetic field (HFA-SPLIV). The high- frequency average of the SPLIV levels (see Clause 3.4.6). The abbreviation for this term is HFA-SPLIV. 3.4.3 relative simulated equivalent telephone sensitivity (RSETS). Difference in decibels obtained by subtracting the RTG + 60 dB SPL from the HFA-SPLITS. The abbreviation for this term is RSETS. 3.4.4 relative test loop sensitivity (RTLS). Difference in decibels obtained by subtracting the RTG + 60 dB SPL from the HFA-SPLIV. The abbreviation for this term is RTLS. 3.4.5 sound pressure level for an inductive telephone simulator (SPLITS). Sound pressure level developed in the coupler by a hearing aid with the gain control at the RTS when the input is the magnetic field generated by a Telephone Magnetic Field Simulator (refer to Clause 3.2.5). The abbreviation for this term is SPLITS. 3.4.6 sound pressure level in a vertical magnetic field (SPLIV). Sound pressure level developed in the coupler by a hearing aid with the gain control at the RTS when the input is a 31.6 mA/m sinusoidal alternating magnetic field parallel to the vertical reference and the input selector of the hearing aid set to T-position. The abbreviation for this term is SPLIV. Good News, ANSI S3.22 committee has decided to make T-coil specification mandatory for quality test inspection

7. www.univ ox.eu Magnetic Field Strength, 400mA/m Coverage area/space (sitting and standing), Should have minimum variations (+-3dB) Magnetic Field Strength, 400mA/m Coverage area/space (sitting and standing), Should have minimum variations (+-3dB)

8. www.univ ox.eu Variation less than +-3dB

9. www.univ ox.eu Magnetic field strength from electrical appliances Magnetic field strength from electrical appliances Received directly by the T-coil NOT by the hearing loop system Received directly by the T-coil NOT by the hearing loop system Less problematic due to stronger regulations of electrical environment Less problematic due to stronger regulations of electrical environment Magnetic field strength from electrical appliances Magnetic field strength from electrical appliances Received directly by the T-coil NOT by the hearing loop system Received directly by the T-coil NOT by the hearing loop system Less problematic due to stronger regulations of electrical environment Less problematic due to stronger regulations of electrical environment

10. www.univ ox.eu Mic T-coil Hearing instrument, microphone/telecoil response

11. www.univ ox.eu Mic Tele-coil Reduced low frequenc y sensitivit y 25dB Hearing instrument, microphone/telecoil response

12. www.univ ox.eu Mic Tele-coil Hearing intrument, microphone/telecoil response Hearing instrument, microphone/telecoil response

13. www.univ ox.eu Mic Tele-coil Hearing instrument, microphone/telecoil response Within +-3dB +-3dBWithin +-3dB

14. www.univ ox.eu It is therefore impossible to judge the full quality of a loop system by using a Hearing Instrument Measurements are mandatory It is therefore impossible to judge the full quality of a loop system by using a Hearing Instrument Measurements are mandatory

15. www.univ ox.eu The specifications for most of the parameters for loops are for vertical directions This corresponds to HI manufacturers placing the T-coil in vertical position The specifications for most of the parameters for loops are for vertical directions This corresponds to HI manufacturers placing the T-coil in vertical position

16. www.univ ox.eu -3dB (@45°) ‏ 0dB=full level Silence! Vertical field Silence!

17. www.univ ox.eu full level Vertical AND Horizontal Field 0dB=full level -3dB (@45°) ‏

18. www.univ ox.eu Increased low frequency response Increased low frequency response Hum harmonics remover Hum harmonics remover Default sensitivity should follow the standard of 400mA/m (125ms, RMS) Default sensitivity should follow the standard of 400mA/m (125ms, RMS) If the sensitivity is set higher in the Hearing Instrument there is a strong risk for high distortion, clipping/saturation when entering a correct installed Loop System. A weak loop must not be compensated by increasing the T-coil sensitivity with a decreased Signal to Noise ratio. Increased low frequency response Increased low frequency response Hum harmonics remover Hum harmonics remover Default sensitivity should follow the standard of 400mA/m (125ms, RMS) Default sensitivity should follow the standard of 400mA/m (125ms, RMS) If the sensitivity is set higher in the Hearing Instrument there is a strong risk for high distortion, clipping/saturation when entering a correct installed Loop System. A weak loop must not be compensated by increasing the T-coil sensitivity with a decreased Signal to Noise ratio.

19. www.univ ox.eu Several channels and modulated/coded loop system. Several channels and modulated/coded loop system. One “standard loop system for world wide use in theatres etc One “standard loop system for world wide use in theatres etc Other channels for school and domestic use. Decreased Signal to Noise ratio. Other channels for school and domestic use. Decreased Signal to Noise ratio. Several channels and modulated/coded loop system. Several channels and modulated/coded loop system. One “standard loop system for world wide use in theatres etc One “standard loop system for world wide use in theatres etc Other channels for school and domestic use. Decreased Signal to Noise ratio. Other channels for school and domestic use. Decreased Signal to Noise ratio.

20. www.univ ox.eu

22. InputInput Acoustic Output switchswitch M M T T HearingInstrumentHearingInstrument Loop Level: Fixed @ 400mA/m for all signals Loop Level: Fixed @ 400mA/m for all signals Speech level=70dB @1m distance Speech level=70dB @1m distance 130dB130dB Gain +60dB Coil Sensitivity 130dB130dB Same output level for M and T-position

23. www.univ ox.eu InputInput Acoustic Output switchswitch M M T T HearingInstrumentHearingInstrument Loop Level: Fixed @ 100mA/m for all signals Loop Level: Fixed @ 100mA/m for all signals Speech level=70dB @1m distance Speech level=70dB @1m distance 130dB130dB Gain +60dB Coil Sensitivity 130dB130dB Same output level for M and T-position Long-term signals:

24. www.univ ox.eu InputInput Acoustic Output switchswitch M M T T HearingInstrumentHearingInstrument Loop Level: Fixed @ 31.6 mA/m for all signals Loop Level: Fixed @ 31.6 mA/m for all signals Speech level=60dB @1m distance Speech level=60dB @1m distance 120dB120dB Gain +60dB Coil Sensitivity 120dB120dB Same output level for M and T-position Long-term signals: