You need digital TV to get audio description (AD), which allows you to hear a verbal description of what is happening on screen in between the dialogue. The service was developed particularly for viewers with sight problems.
AD is available on Freeview, Freesat, Sky and Virgin Media. The range of channels and programmes covered varies between the platforms and between different broadcasters. The BBC currently has AD on 10% of the content on its main channels.
AD is built into Freesat, Sky and Virgin Media set-top boxes, but not all Freeview boxes or digital TVs offer it. AD is also available on BBC iPlayer.