Playing .m4b Files?

[Hart Larry]

While on mutella, I grabbed a 21mb .m4b file of the 3rd Presidential debate. 
So far I tried playing it with ogg123, mpg321, mytrplayer, and mplayer.  None 
of them liked it.  Then I looked in google--and it claims they are the same as 
.m4a, so I renamed it but no luck.  The file command tells me it is data.  So 
can some1 please tell me how to play .m4b files in Fedora 1 with a DecPc and 
speakup.  Thanks so much in advance
Hart