ABSTRACT
A highly audible interfering sound may be created in hearing aid outputs by the pulsatile electromagnetic signals generated by some digital cellular telephones (DCT). At its worst, this undesirable signal totally dominates the audio processing of the hearing aid and makes it unusable. The degree of interference generated is a function of the type of DCT technology, the type or style of hearing aid, and how many precautionary measures have been taken in the hearing aid design to reduce interference. Engineers from telephone companies and hearing aid engineers have worked together with the encouragement of hearing aid consumers and the Federal Communications Commission to reduce this interference problem. As a result, considerable strides have been made, particularly by hearing aid companies, toward improving the immunity of hearing aids to DCT interference. Many of these same engineers have participated in national and international standards committees to develop viable methods for assessing the amount of immunity to DCT interference provided by hearing aids and the emission levels from DCTs. The process of harmonizing these standard assessment techniques is ongoing.
KEYWORDS
Interference - immunity - emission - digital - cellular - telephone
