Radio microphone hearing aids: Issues surrounding the use of an environmental microphone

Journal/Book: Deaf Educ. 1997; 21: C/O G F E Clark, 2 Gaters Gardens, Sandford, Crediton, England EX17 4LU. British Assoc Teachers Deaf. 3-18.

Abstract: This paper examines some of the theoretical and practical issues surrounding the choice of mode (radio only or radio and environmental microphone) and setting the gain of radio microphone heaving aids. The radio only mode should never be used with young children, even when this mode can be obtained by a voice priority switch that is only active when the teacher is speaking. The combined mode does nor give as good a signal-to-noise (S/N) ratio as the radio only mode but it still gives a consistent output level and therefore minimises the adverse effects of the child being some distance from the teacher. In the combined mode the S/N ratio can be increased by increasing the gain of the radio channel. The difference between the gain of the radio channel and that of the conventional aid should be 10 dB or less unless the listener has a small dynamic range.

Note: Article Rowson VJ, Univ Manchester, Ctr Audiol Educ Deaf & Speech Pathol, Oxford Rd, Manchester M13 9PL, Lancs, ENGLAND

Keyword(s): FM SYSTEMS

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