ITU-R - International Telecommunication Union/ITU Radiocommunication Sector
Scope
Introduction Many forms of hearing impairment cannot be satisfactorily improved by the provision of amplification only. Difficulties such as distortion in the residual hearing@ loss of binaural directivity@ emphasis of environmental noise and room reverberation lead to the use of systems incorporating the placement of the microphone near to the speaker rather than to the listener.