[Tfug] Text-to-speach conversion - straight from plain text to an audio file?

[Jim March]

Folks,

I have a book currently in a big .PDF file.  I have a friend who, due
to severe dyslexia, can't read anything that long.  But he listens to
audiobooks and often "reads" big text-heavy websites via software
speech synth.

Is there an app under Linux, or even a website somewhere, that can
"read" a big chunk of text in at once and output an .MP3 or .OGG or
whatever audio file?  That would allow him to "read" it even when away
from his computer.

Jim