Here are some excerpts from the "One flew over the cuckoo's nest" by Ken Kesey
I’m the one been here on the ward the longest, since the Second World War. I been here on the ward longer’n anybody. Longer’n any of the other patients. The Big Nurse has been here longer’n me.

I was born dead an’ life was hard. I’m tired. I’m tired out talking and standing up. I been dead fifty-five years.

All this morning I been waiting for them to fog us in again. The last few days they been doing it more and more. It’s my idea they’re doing it on account of McMurphy.

Won’t they figure I been hearing all these years, listening to secrets meant only for their ears?
According to the English tenses table I was taught in a school I would expect here either "was/were" or "have/has been" for the colored entries. Is there any implicit usage of such constructions or what is implied in the sense of grammatical tense with such a usage of "been"?