What was Charles Bronson's accent?

Misidentities on this thread prompt me to ask about something I’ve always wondered: What accent did the actor Charles Bronson have?

I understand he was of Slavic descent, and grew up in a Polish-Slavic neighborhood near Pittsburgh. But I’ve known plenty of people of that background and locale (I grew up 75 miles south of Pittsburgh) and don’t remember any of them sounding like Bronson.

The Simpsons DVD boxsets contain commentary from Groening, et al, where they refer to the ‘wiseguy’ voice evident in some of the incidental characters, which they acknowledge is similar to Bronson’s – could it be an affectation to enhance Bronson’s ‘tough guy’ personna?

Other than “intimidating,” I can’t think of an adjective. I do think it’s cool that he was in “The House Of Wax,” with Vincent Price, though. Of course, he didn’t have an accent in that because he was mute.

FUS, please drop me an email if you would - I think we share some interests that I’d like to talk with you about.