Community Research and Development Information Service - CORDIS


The electromagnetic compatibility with high-frequency electromagnetic fields was measured on 20 different types of hearing aids. It could be proved that the sound pressure generated in the hearing aid increases quadratically with the amount of the field strength. The interference behaviour of the hearing aids can, therefore, be calculated for any field strength using the measurement results obtained at one specific field strength.

At carrier frequencies of 910 MHz and 1705 MHz, which are of special importance in Germany, output-related noise levels between 37 dB and 121 dB were produced at the ear by the 20 hearing aids. These levels correspond to sound pressure levels at the entrance of the hearing aid (input-related interference levels IRIL) between -10 dB and +72 dB. It turned out that no hearing aids are so far available which are immune at all common carrier frequencies of mobile telephones. However, there are some few hearing aids which can be used up to a field strength of 80 V/m at particular carrier frequencies. Such a field strength can occur, for example, at the ear of a mobile telephone user. .

Additional information

Authors: RICHTER U, Physikalisch Technische Bundesanstalt, Braunschweig (DE);SCHÄDLER M, Physikalisch Technische Bundesanstalt, Braunschweig (DE)
Bibliographic Reference: Report: DE(1996) 46pp.
Availability: Available from Physikalisch Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (DE)
ISBN: ISBN 3-89429-810-3
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