EVALUATION OF NOISE IN HEARING INSTRUMENTS CAUSED BY GSM AND DECT MOBILE TELEPHONES

The annoyance of noise in hearing instruments caused by electromagneti c interference from Global Systems for Mobile Communication (GSM) and Digital European Cordless Telecommunication (DECT) mobile telephones h as been subjectively evaluated by test subjects. The influence on spee ch recognition from the GSM and DECT noises was also determined. The m easurements involved 17 hearing-impaired subjects. The annoyance was t ested with GSM and DECT noise, each one mixed with continuous speech, a mall environment noise, or an office environment noise. Speech recog nition was tested with the DANTALE word material mixed with GSM and DE CT noise. The listening test showed that if noise level is acceptable so also is speech recognition. The results agree well with an investig ation carried out on normal-hearing subjects. If a hearing instrument user is to be able to use a telephone without annoyance, the input-rel ated noise level must not exceed 47 dB SPL for GSM and 46 dB SPL for D ECT.