The MP, who was born blind, said deaf people were struggling with subtitles such as "the Arsenal player has been fouled by a zebra" (instead of referring to footballer Patrice Evra) and "looking for the prince of chemical and bionicle weapons" (principally chemical and biological weapons).
He complained that blind people were left frustrated when foreign dramas and documentaries were not dubbed.
Mr Blunkett said broadcasters were failing to deal with a "growing problem" of an ageing population, suffering from blindness and deafness.
He said: "Broadcasters talk a good deal about equality, but preaching is not enough. In an ageing population, people with hearing and sight impairments are becoming part of the mainstream. It's no longer about a minority: we are a major sector of the viewing public, and we have the same rights as everyone else who pays the licence fee.
"Today, the way TV executives worship the cult of youth seems to be an unstoppable fetish. It is the trendy, the metropolitan and ... the under-40s who determine what we view and what we listen to. But much of the spending power reflects an older age group. The ageing population wields a very powerful incentive: our financial muscle."
He added: "There is an increasing tendency for overseas material to be broadcast without being dubbed. I appreciate many people don't like dubbed dialogue, but if you're blind it's invaluable - you can piece together the storylines simply by listening to what is said."
In May, new director-general Tony Hall said the BBC could look at how to stop actors "muttering" in its TV dramas, and that the corporation was trying to address the problem of background music making it difficult for some, particularly older viewers, to hear what is being said on programmes.