Big pictures and small screens; how television sound research can work with, and for, hard of hearing viewers

Hearing loss affects one in six people in the United Kingdom and, given an ageing population, this figure is increasing.1 Numerous studies highlight that improvements in the intelligibility of television sound are required to increase television’s accessibility to individuals with hearing loss.2–4 Recent developments in broadcast technology, in particular the advent of object-based broadcasting, show the potential to deliver real improvements in television accessibility.4–7 Effective strategies to improve the intelligibility of television sound are predicated on intelligibility evaluation methods which are ecologically valid, repeatable and representative of the varied characteristics of hearing loss. This paper presents a review of such evaluation methods in the context of their use in, or applicability to, television sound research. The paper first outlines the prevalence and characterisation of hearing loss, as well as definitions of intelligibility. Current problems with television accessibility for hard of hearing viewers and how object-based broadcasting may offer solutions are summarised. Intelligibility evaluation methods for hearing impaired individuals and objective metrics of intelligibility are then described. The use of such methods previously in television sound research, in addition to the use of related subjective methods, is reviewed. The repeatability, ecological validity and how these methods may be sensitive, or insensitive, to the characteristics of hearing loss are then examined. Finally, the importance of including end-users in the research and evaluation process is discussed