IEEE C63.19-2007 Historical

The purpose of this standard is to establish categories for hearing aids and for WDs that can indicate to healthcare practitioners and hearing aid users which hearing aids are compatible with which WDs and to provide tests that can be used to assess the electromagnetic characteristics of hearing aids and WDs and assign them to these categories. The various parameters required, in order to demonstrate compatibility and accessibility are measured. The design of the standard is such that when a hearing aid and WD achieve one of the categories specified, as measured by the methodology of this standard, the indicated performance is realized. In order to provide for the usability of a hearing aid with a WD, several factors must be coordinated as follows: ⎯ RF measurements of the near-field electric (E) and magnetic (H) fields emitted by a WD to categorize these emissions for correlation with the RF immunity of a hearing aid ⎯ H-field measurements of a WD emitted via the audio transducer associated with the T-Coil mode of the hearing aid, for assessment of hearing aid performance ⎯ Measurements with the hearing aid and a simulation of the categorized WD T-Coil emissions to assess the hearing aid RF immunity in the T-Coil mode The WD's RF and audio band emissions are measured. Hence, the following are measurements made for the WDs: 1) RF E-field emissions 2) RF H-field emissions 3) T-Coil mode, magnetic signal strength in the audio band 4) T-Coil mode, magnetic signal and noise articulation index 5) T-Coil mode, magnetic signal frequency response through the audio band Corresponding to these quantities, the hearing aid is measured for the following: a) RF immunity in microphone mode b) RF immunity in T-Coil mode The hearing aid T-Coil reception characteristics are also important when assuring the usability of the T-Coil mode. When these characteristics are coordinated, the goals of compatibility and accessibility are accomplished. Two principal conditions expose hearing aid equipped users to undesired RF electromagnetic disturbances. The far-field condition corresponds to the type of field a hearing aid equipped bystander would experience when adjacent to a WD user. The near-field condition corresponds to the more intense fields that a hearing aid equipped user of a WD would experience. This standard assesses the near-field or user condition. This standard describes preferred test methods and test facilities and, in some cases, alternative test methods and 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 set forth in this standard, shall be fully described in the test report. Wherever the word shall is used in this standard, it indicates something mandatory. The word should indicates something that is advisory. The word may indicates an option, which is at the discretion of the test engineer.