The purpose of this standard is to provide tests and establish requirements for hearing aids and for WDs that allow a hearing aid user to effectively use a WD when both the hearing aid and WD meet the requirements of this standard. The various parameters required in order to demonstrate compatibility are measured. The design of the standard is such that when a hearing aid and a WD achieve the specified requirements, as measured by the methodology of this standard, the user of a hearing aid can effectively use a WD. In order to provide for the usability of a hearing aid with a WD, several factors are coordinated, as follows: The field strength emitted by a WD must not exceed the RF immunity of the hearing aid. The T-Coil baseband H-field transmission of the WD must be compatible with the T-Coil mode of the hearing aid. The magnetic noise from the WD in the T-Coil band must not degrade the reception quality to unacceptable levels. Both the WD's RF and audio-band emissions are measured. Hence, the following measurements are made for the WDs: a) RF amplitude modulation characteristics and power level or, optionally, near-field E-field emissions b) T-Coil mode, magnetic signal strength in the audio band c) T-Coil mode, magnetic noise in the audio band d) T-Coil mode, magnetic signal frequency response in the audio band Corresponding to these quantities, the hearing aid is measured for the following: 1) RF immunity in microphone mode 2) RF immunity in T-Coil mode This standard describes preferred test methods and test facilities. If alternative test methods or facilities are employed, every effort shall be made to establish correlation with the preferred ones. Any deviation from the preferred test methods, as specified in this standard, shall be fully described in the test report.