This part of IEC 60118 in principle covers all relevant EMC phenomena for hearing aids. EMC phenomena, such as RF emission and electrostatic discharge, are not currently known to be a significant problem in connection with hearing aids and are therefore not dealt with. Based on new knowledge, they could be considered in connection with future revisions or extensions of this standard. Hearing aid immunity to high frequency electromagnetic fields originating from digital wireless devices operating in the frequency ranges 0,8 GHz to 0,96 GHz and 1,4 GHz to 2,48 GHz is currently identified as the only relevant EMC phenomenon regarding hearing aids. Future editions of this part of IEC 60118 may add tests for other frequency bands, as they come into more common use. IEC 61000-4-3 is the basis for relevant EMC tests to be conducted on hearing aids. Measurement methods and acceptance levels are described in this part of IEC 60118. For the purpose of this part of IEC 60118, two immunity classes of hearing aids are defined (see 3.1) related to their use. "Bystander compatible" ensures that a hearing aid is usable in environments where digital wireless devices are in operation in the proximity of the hearing aid wearer. "User compatible" hearing aids ensures that a hearing aid is usable when the wearer is using a digital wireless device at the wearer’s own aided ear. Measurement methods for hearing aids with non-acoustic outputs and for hearing aids connected to other equipment by cables are not given in this standard.