[pdftex] making pdf document accessible using LaTeX

[Sauro Cesaretti]

Hello everyone,

I'd like to ask some information to create accessibile pdf documents using
LaTeX.
I have known that there are some guidelines to create as such, how can I use
these guidelines in LaTeX?
In particular, I'd like to make mathematical expressions accessible and
readable with screen readers.
I'd like to do giving one alternate output using LaTeX notation.
Example, reading a pdf document and will encounter 
a formula that for screen readers tools  is a graphical element,  I'd like
to read it driving the information with LaTeX notation.

Could you help me with some information to do these things?
are there some LaTeX packages for this?

thank you in advance
best regards, Sauro