[accessibility] Problem: screen reader + ligatures

[Jonathan Fine]

Hi

This arose from a post from Sanchit Ghule, a blind user of LaTeX who's
reported that his screen reader skips ligatures, such as "fi" in
"significant".

My first step is a web search.  I searched for 'screen reader ligatures'.
I've found the following interesting links (followed by my brief comments).

1. https://www.mobileread.com/forums/showthread.php?t=296719
A discussion in 2018 among contributors to the MobileRead library. They
mention Microsoft's TTS (Text To Speech). The participants are well
informed and cooperative. The conclusion (on page 3 of the thread) is that
two separate versions (sighted and blind) would be best.

2. https://miktex-users.narkive.com/t5tuU541/suppressing-ligatures
A discussion in 2002 in MikTeX users forum. Notes that ligatures cause
search to fail, as well as screen readers. Discussion focuses on preventing
ligatures, mainly via active characters and virtual fonts (which I consider
impractical).

3. https://github.com/google/material-design-icons/issues/732
Ligatures causing accessibility issues
Issue raised in 2018. Text in icons is read by screen readers, and a
"ligature-method" is used. "The point is, the default solution with
ligatures, albeit elegant, does come with a whole package of accessibility
issues that needs to be addressed."  No responses, and the issue is still
open.

4. https://paizo.com/threads/rzs2u5ra?The-ff-typographic-ligature
Paizo is a role-play game publisher, eg Pathfinder. This 2017 post is about
the failure of search in Paizo PDFs for words such as "janderhoff". The
problem was reported to the same forum in 2010. The thread mentions tagged
PDF.

5. https://accessibility.oit.ncsu.edu/generating-accessible-pdf-documents/
IT Accessibility page. States "Fonts are mapped into standard Unicode
equivalents, ensuring reliable translation of all text and correct
interpretation of ligatures and hyphens. This allows the screen reader to
correctly read all characters and words." BINGO. An accurate and succinct
statement of the problem.

I've also searched for 'screen reader ligatures latex'. This gives
additional interesting results. Mostly, I've not had time to add comments.

6.
https://tex.stackexchange.com/questions/262009/historic-font-and-missing-ligatures

7.
https://subscription.packtpub.com/book/hardware_and_creative/9781784395148/3/ch03lvl1sec37/enabling-the-searching-and-copying-of-ligatures

8. https://tug.org/pipermail/pdftex/2018-September/009143.html

9.
https://www.homepages.ucl.ac.uk/~ucahmto/elearning/latex/2019/05/06/accessibility-regulations.html
Interesting page, but doesn't contain "ligatures".

10. https://latex.org/forum/viewtopic.php?t=21808
2012 post: Searchable ligatures in PDF docs from XeTeX

11.
https://ctan.math.washington.edu/tex-archive/macros/latex/contrib/tagpdf/tagpdf.pdf
2021: This package is not meant for normal document production. It is
mainly a tool to research tagging
It's interesting that in this PDF document "difficult" has the "fi"
ligature AND "difficult" works for search AND for copy-and-paste.

That's all for now.
--
Jonathan
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