Hearing aids are technical instruments which compensate for congenital or acquired hearing impairments which are not amenable to causal therapy. Hearing aids amplify and modulate the sound, i.e. the acoustic signal, upstream of the ear's actual sense organ, the inner ear. Various types of device are available, comprising a microphone, signal processor (e.g. amplifier), energy source and receiver.
Already known for some time are hearing aids having radio reception units which receive modulated and/or coded audio signals from a transmitter, demodulate and/or decode them and output them suitably processed (mainly amplified) to the hearing aid wearer as sound waves. Such systems are used, for example, in public buildings such as churches, or also in the hearing aid wearer's living area, in order to feed certain types of sound information to the hearing aid not only via sound waves but directly into the hearing system via radio.
Some of these systems use a coding which, in the event of transmission errors, produce unpleasant sounding noises, so-called artifacts, e.g. loud bleeping or clicking noises, before sufficient information for correct decoding is available to the decoder again after the transmission error. A frequent cause of transmission errors is an excessively weak signal reaching the receiver, e.g. because the hearing aid wearer has moved too far away from the transmitter.