Zawinal writes:
I've never heard of talking broad, I'll have to look it up.
You must've, surely. Saying someone has a broad accent just means they have a strong one, really.
For example:
"He spoke with a broad Somerset accent."
The opposite might be "soft", meaning the accent is less pronounced.
There are people who speak "broad Glasgwegian" and then there are people from Glasgow who can actually be understood by non-Scottish English speakers.