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I was asked a question during a LaTeX how-to session which I did not have a good answer for. The person asking is interested in accessibility software which is able to read LaTeX formatted equations in a meaningful way.

Example:

\documentclass{minimal}
\begin{document}
    \begin{equation}
        x^2 + y^2 = z^2
    \end{equation}
\end{document}

When the document is read by the Okular screenreader, it sounds like:

x two plus y two equals z two

but what we really are showing should sound like:

x squared plus y squared equals z squared

Such accessibility options are available for other equation editors, such as MathJax. This question was asked before, but closed due to unclear questioning. So allow me to produce specific questions:

Is there:

  1. A PDF reader which interprets mathematical conventions such as superscripts and symbols in a mathematically meaningful way?
  2. An external tool which reads equations out loud directly from the LaTeX style?
  3. A tool within LaTeX which can add comments to a PDF versions of the document which are invisible, yet listenable? (similar to alt text in images)
6
  • 1
    In the core pdf is not accessible. The pdf contains only symbols without mathematical meaning so only rather simple equations are read in a sensible way. It is possible (with tagpdf or Accsup and other packages) to add more info but it unclear if and how screen readers makes use of them and which mark-up they want. My questions to NVDA about this wasn't answered. Oct 12, 2018 at 18:47
  • I've been playing with the pdfcomment package. I can add an alternate version but not turn off the original. Oct 13, 2018 at 13:47
  • 1
    A number of projects have faltered due to poor funding some still standing are MathPlayer and lambdaproject.org both mentioned here researchgate.net/post/…
    – user170109
    Oct 13, 2018 at 19:09
  • 1
    Documentation for the axessibility package which adds LaTeX code as hidden comments to pdf files suggests that it works with the NVDA and JAWS screen readers. Apr 29, 2019 at 13:11
  • 1
    Blind academics in my field typically request the source code.
    – JPi
    Aug 23, 2019 at 18:17

1 Answer 1

5

Using my new tokcycle package (https://www.ctan.org/pkg/tokcycle )...I find the result pleasingly legible, when read audibly via the Adobe Reader.

This MWE relies on you having a new enough LaTeX installation to support the new \expanded primitive. If not, you can, for the time being, change the \tcremap[x] in the \speakifytext definition to \tcremap[1] and also change the \noexpand\pauseafter (2 instances) to \pauseafter. The net effect of this change is that the token register \cytoks that holds the transformed text, will contain things like \tcmapto^ rather than , raised to the power. That is to say, the transformation occurs when the token register is typeset, rather than before being placed into the token register.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[margin=1in]{geometry}
\usepackage{tokcycle,amsmath}
\tokcycleenvironment\speakifytext
  {\tcremap[x]{##1}}
  {\processtoks{##1}}
  {\tcremap[1]{##1}}
  {\addcytoks{##1}}
\newcommand*\tcmapto[3][\noexpand\pauseafter]{%
  \expandafter\def\csname tcmapto\string#2\endcsname{\text{#3 }#1}}
\newcommand*\tcmaptomacro[3][\noexpand\pauseafter]{%
  \expandafter\def\csname tcmapto\string#2\endcsname{#3#1}}
\newcommand*\tcremap[2][1]{\ifcsname tcmapto\string#2\endcsname
  \addcytoks[#1]{\csname tcmapto\string#2\endcsname}\else\addcytoks{#2}\fi}
\newcommand\pauseafter[1]{\tctestifcatnx#1\relax{#1}{#1,}}
\tcmapto[] ({, left paren,}
\tcmapto[] ){, right paren ,}
\tcmapto   ^{, raised to the power}
\tcmapto   _{, sub}
\tcmaptomacro[] \frac\readfrac
\newcommand\readfrac[2]{\text{, the fraction, } #1 \text{, divided by, }#2%
  \text{, end fraction, }}
\begin{document}
\speakifytext
\section{Making \LaTeX{} Math Audibly Legible}
We use the new tokcycle package to transform math symbols into spoken text.
See if you agree.
    \begin{equation}
       x_i^2 + y^2 = (z^2 + 1)
    \end{equation}
Or this one:
    \begin{equation}
       Z = \frac{x+1}{2}
    \end{equation}
\endspeakifytext
\end{document}

enter image description here

Just remove the two lines, \speakifytext and \endspeakifytext, and recover the original output.

enter image description here

See also this question, which I find related: In which way have fake spaces made it to actual use?

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  • This answer has good prospects, but I am having trouble verifying your solution independently. It looks like \speakifytext is not defined in the CTAN version of your package. Is this correct or have I missed something?
    – WesH
    Aug 23, 2019 at 18:55
  • @WesH \speakifytext is defined in the MWE via \tokcycleenvironment\speakifytext {\tcremap[x]{##1}} {\processtoks{##1}} {\tcremap[1]{##1}} {\addcytoks{##1}} Aug 23, 2019 at 19:00
  • so it is, yet it may be doing something funny to the equation environment. I'm getting multiple undefined control sequences for the math at each -eme so the error text, in order, is: "x_", "x_i^", "x_i^2 + y^", and so on.
    – WesH
    Aug 23, 2019 at 19:06
  • @WesH Let me download the CTAN version and see if it matches my local version. Aug 23, 2019 at 19:07
  • 1
    The discussion in chat resulted in discovering an error which arises in pdftex versions lower than v1.50. This is an excellent solution to the problem posed by the original question. Please do not be offended if I do not mark the question as "solved" so we invite more potential solutions to be reported.
    – WesH
    Aug 23, 2019 at 21:02

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