The Australian experience: global system for mobile communications wireless telephones and hearing aids

A digital, wireless telephone system, the Global System for Mobile Communications (GSM), was introduced in Australia in 1993. Studies were conducted at the National Acoustic Laboratories to determine how the use of GSM mobile telephones (i.e., wireless telephones) causes interference in hearing aids and how hearing aids could be made more immune to such interference. A measurement system was developed, and measurements are presented for a variety of standard and treated hearing aids. Effective treatments include the addition of shunt capacitors to the hearing aid circuit and shielding by applying a conductive coating to the hearing aid case. Some recently produced microphones also increase immunity. High immunity levels can be achieved in future hearing aids, sufficient to prevent interference from other people's use of a wireless telephone and that often permit use of digital mobile telephones by hearing aid users. Audiologists will have an increasing role in advising hearing aid wearers on the use of wireless telephones or other communications equipment.