Why didn't Sirius escape? Can Dementors talk?

[jessewilliams44 at yahoo.com]

No: HPFGUIDX 24338

Sirius did not escape because the dementors affected him even when he 
was in his animargas form.  "Harry and Hermione heard a distant 
yelping, Sirius is in trouble"  The dementors could effect Sirius in 
either form, although it was harder when he was in animal form 
because his emotions were less complex.   Which brings us to my other 
questions how do the dementors communicate?  In POA early chapters 
(sorry do not have book with me, I'm at work)  Mr. Weasley tells Mrs. 
Weasley that Fudge went to Azkaban, and Black was sane he even asked 
Fudge for his newspaper.  He also says that the guards told Fudge 
that Black had been talking in his sleep always the same words. "He's 
at Hogwarts."  Do the dementors speak?  Or perhaps if they are human 
spirits of some sort can they convey their thoughts in writing?  Or 
could their be other guards that are more humanlike and that still 
talk?  Maybe even human guards, IMO not likely they would be drained 
of all of their happy thoughts.

Jesse