Hearing supportive algorithm with self-adjustment user interface integrated in the telephone network
Making phone calls is still challenging for hearing-impaired listeners. In this study a hearing-aid algorithm is presented which was integrated in the telephone network and which allowed listeners to adjust the algorithm settings to their individual preferences using the DTMF tones of the keypad. The algorithm was evaluated in a field trial by 41 hearing-impaired listeners. First, listeners filled out a questionnaire concerning the technical equipment and the user behaviour using the phone. Second, they rated the self-adjusted processed signal compared to the original recordings. The results show that phone calls are still challenging for hearing-impaired listeners and coupling problems between receiver and hearing aids are still present. Only about one third of the subjects aligned their mobile phone to the microphones of the hearing aid. The remaining participants directly held their mobile phones to the ear or remove the hearing aid for making a call. The direct comparison of unprocessed and processed signals showed that the proposed self-adjustable signal processing algorithm could significantly improve speech intelligibility, sound quality, and listening effort. Amplification settings are partly contrary to what was expected from the audiometric threshold indicating that explicit user feedback is required for individual sound optimization.