Audio Deja Vu: Audio Formatted Math On The Emacspeak Desktop
1 Overview
This article previews a new feature in the next Emacspeak release —
audio-formatted Mathematics using Aural CSS. Volker Sorge worked
at Google as a Visiting Scientist from Sep 2012 to August 2013, when
we implemented math
access in ChromeVox — see this brief overview. Since leaving
Google, Volker has refactored and extended his work to create an Open
Source Speech-Rule-Engine implemented using NodeJS. This
speech-rule-engine can be used in many different environments;
Emacspeak leverages that work to enable audio-formatting and
interactive browsing of math content.
2 Overview Of Functionality
Math access on the Emacspeak desktop is implemented via module
emacspeak-maths.el — see js/node/Readme.org in the Emacspeak GitHub
repository for setup instructions.
Once loaded, module emacspeak-maths provides a Math Navigator that
implements the user interface for sending Math expressions to the
Speech-Rule-Engine, and for interactively browsing the resulting
structure. At each step of the interaction, Emacspeak receives math
expressions that have been annotated with Aural CSS and produces
audio-formatted output. The audio-formatted text can itself be
navigated in a special Spoken Math emacs buffer.
Module emacspeak-maths.el implements various affordances for
dispatching mathematical content to the Speech-Rule-Engine — see
usage examples in the next section.
3 Usage Examples
3.1 The Emacspeak Maths Navigator
- The maths navigator can be invoked by pressing S-SPC (hold
down Windows key and press SPC) — this runs the command emacspeak-maths-navigator/body. - Once invoked, the /Maths Navigator can be used to enter an
_expression_ to read. - Pressing SPC again prompts for the LaTeX math _expression_.
- Pressing RET guesses the _expression_ to read from the current context.
- The arrow keys navigate the _expression_ being read.
- Pressing o switches to the Spoken Math buffer and exits the
navigator.
See the relevant chapter in the online Emacspeak manual for details.
3.2 Math Content In LaTeX Documents
- Open a LaTeX document containing math content.
- Move point to a line containing mathematical markup.
- Press S-SPC RET to have that _expression_ audio-formatted.
- Use arrow keys to navigate the resulting structure.
- Press any other key to exit the navigator.
3.3 Math Content On Wikipedia
- Open a Wikipedia page in the Emacs Web Wowser (EWW) that has
mathematical content. - Wikipedia displays math as images, with the alt-text giving the
LaTeX representation. - Navigate to some math content on the page, then press S-SPC
a to speak that content — a is for alt. - As an example, navigate to Wikipedia Math Example, locate math expressions on that page, then
press S-SPC a.
3.4 Math Content From The Emacs Calculator
- The built-in Emacs Calculator (
calc) provides many complex
math functions including symbolic algebra. - For my personal
calcsetup, see tvr/calc-prepare.el in the
Emacspeak GitHub repo. - This setting below sets up the Emacs Calculator to output results
as LaTeX: (setq calc-language 'tex) - With the above setting in effect, launch the emacs Calculator by
pressing M-##. - Press ' — to use algebraic mode — and enter
sin(x). - Press a t to get the Taylor series expansion of the above
_expression_, and press x when prompted for the variable. - This displays the Taylor Series expansion up to the desired
number of terms — try 7 terms. - Now, with Calc having shown the results as TeX, press S-SPC
RET to browse this _expression_ using the Maths Navigator.
4 And The Best Is Yet To Come
This is intentionally called an early preview because there is still
much that can be improved:
- Enhance the rule engine to infer and convey more semantics.
- Improved audio formatting rules to better present the available information.
- Update/tune the use of Aural CSS properties to best leverage
today's TTS engines. - Integrate math-reading functionality into more usage contexts in
addition to the ones enumerated in this article.
5 References
- Youtube Video from early 2013 demonstrating Math Access in Chrome
- AllThings Digital outlining math access — published June 2013.
- Assets 2016 publication describing this work.
- js/node/aster-math-examples.tex Collection of math examples in
LaTeX from AsTeR. Used to progressively improve speech-rules and
the resulting audio-formatted output - Speech-Rule-Engine on github.
- Speech-Rule-Engine in action: Accessible Maths in all browsers