Accents and communications...interesting topic.
My grandparents lived with us from the time from about when I was 2. They were wonderful people, as were my parents. My GF on my mother's side was born in Ireland, and I used to hang around with him an awful lot, from this time on.
Back then (early '50's) there were quite a few older men in the neighborhood, my grandfather's age and pretty well all of them had been born in either England, Ireland, Scotland or Germany. They were all retired and would invariably gather around in each other's backyard...in the gardens...to shoot the breeze. As often as not, there I would be, part of the conversation circle, ( albeit being seen and not heard
), listening intently to all these men...jabbering away in heavy Irish, Scottish, English and German accents. I recall that I found the discussion of the day fascinating...even if some of it was not readily understandable by me, at the time.
Fast forward about 20 + years and I was in the UK, traveling by overnight rail, one Bank Holiday from Edinburgh to London in a compartment (not sure what they call it in GB) within a train car. There were four of us, me, wife and two Brits, one fellow from Glasgow, the other man from Liverpool. We were all within about 5 years of each other and thus shared many interests.
It was a long, but pleasant journey and we had almost a continual discussion. My wife and I have Canadian accents and the Glaswegian and Liverpudlian could readily understand everything that we North Americans said. But when it came to the two British men understanding each other...it was very difficult for them to understand each other....due to each other's thick accent.
There were many times ...when the Glaswegian would say something to the Liverpudlian and the Liverpool man would look completely confused. Generally, I would step in then and 'interpret' as it were...by saying...no...what he is saying is . ...etc. etc., and of course vice versa where the fellow from Glasgow would not be able to completely understand what the guy from Liverpool was saying.
It got to the point where one Brit said to the other...isn't it amazing...we live about 400 miles from each other, have difficulty understanding what each other is saying, but can readily understand what the Canadian is saying...even though he lives about 6000 miles away from us...and on top of that, he has to interpret for each of us.
My assessment at the time and still current, was here we had a tale of two Brits.
One lived in Scotland, the other England, one country known as the United Kingdom, but they were separated by language....one language...English..due to what was to them, an almost impenetrable accent barrier.
The two men asked me if I had any theories as to why I could understand them , but they couldn't understand each other. I replied and told my story about hanging around my grandfather when I was young and always listening to a variety of English, Scottish, Irish...and German...heavily accented conversations. All that very early experience developed an 'ear' for British accents....which came in handy when I was an adult.