Actor

I see some actors that are from America that can speak both American and British accents. Same thing with British or Australian actors.

Most if not all of them are required to use a speech dialect coach if their accent is really thick, and can’t hide it naturally. Some are just naturally able to do it, but not all. The serious actors use a dialect coach. I know when British actors come over to the U.S and do American movies, they must sound more American so they use a dialect coach to hide their accent or are able to do it naturally from good listening skills and they just wing it. For Example Christian Bale in "American Psycho", "Batman trilogy". Heath LEdger is another one. He was able to hide his too, but in his earlier work his accent tended to come out when saying certain words thats how I knew. Even actors like Robert Pattionson. The serious actors hide their accents. Most of the UK actors are serious actors anyway.

I work at a publisher and they are planning to publish listening comprehension exercises (English is not a first language in my country). How do you find people suitable for recording the conversations? Are there companies that specialize in this? The speakers have to speak clearly and be good actors as the scripts and the questions are quite complicated.

The same way that you find ordinary actors, through "Spotlight"

I am not asking who you think are the best character actors. Kevin Spacey and Edward Norton are fantastic actors but are fairly limited insofar as charisma. Arnold and Bruce Willis aren’t especially gifted actors but undeniably charming and magnetic.

Who are your choices?

James Dean is the ultimate actor with charisma and screen presence. In only three films he changed how acting is done, affected a generation of teens in the 50s, and became a legend.