Speech Quality Improvement of TV-Sets for Hearing-Impaired Older Adults

Flat TV-sets sacrifice space for built-in loudspeakers and this implies a degradation of the speech quality, especially for hearing-impaired older adults. Many elderly people report having difficulty understanding speech on TV, even with hearing aids. In the study, a Transfer Function (TF) that improves the listening experience for the above categories of listeners is validated for Rai, the Italian TV broadcasting company. A Digital Audio Optimizer dynamically equalizes the sound level, in real-time, before the transmission to the broadcasting tower. It implements a TF that amplifies the frequency range between 1 kHz to 4 kHz, which is more important for speech intelligibility, with a particular boosting of the one-third octave band of 4 kHz. Subjective tests of the proposed TF have been carried out in a laboratory in compliance with the standard ITU-R BS.1116-3 with 31 hearing-impaired older adults and a commercial flat-screen TV-set. Results showed a statistically significant slight improvement in the perceived audio quality of 24.3%, over three genres, i.e., “Speech”, “Singing and Music” and “Sport”. This work follows a previous study on 72 normal-hearing subjects where the same methodology was applied, which involved three commercial flat-screen TV-sets and the same genres. The perceived audio quality was judged improved by the 25.3% on average.