What are the technology issues involved in making math accessible?
Learning Points:
 Although some educators have ignored the importance of accessible
math in the past,
these attitudes are now changing due to the availability of new technologies.
 By using universally designed math technologies like MathML to create
accessible math equations, the resulting content will also
provide for alternative access
to meet a student's special access needs.
 Most math equations currently used in digital environments like the
Web are simply static bitmaps (digital drawings) of equation images, and are
inherently inaccessible.
 Using MathML provides a number of
accessibility benefits and produces math equations that can be both
rendered visually on the screen and also available through alternative
access means.
 Turning math expressions
into audio form can be a very effective form of alternative access for
people who have visual or learning disabilities. Images of equations do not
by themselves supply information to support any form of audio rendering, but
coherent and consistent audio rendering of math expressions is available
when using MathML.
 Since there are many users who can see but who have some form of
visual impairment, the need to enlarge
mathematical equations on a computer screen is very common. Using MathML
provides for user flexibility to change visual aspects such as the size and
color of the font as well as the background of the display.

Synchronous highlighting of math equations with audio can be beneficial
for students with learning disabilities or attention deficit disorders, as
well as for students with low vision. Math equations which have been encoded
in MathML can permit a range of highlighting reinforcement options.
 The ability to provide math access through refreshable braille
displays and hard copy braille output is important for both blind and
deafblind users. Math images cannot be accessed by braille, but
braille access to math
encoded in MathML can be provided.
 The ability to better comprehend longer or more complex mathematical
equations in audio form is aided by
user navigation within a math
equation. This is not feasible with prerecorded audio files or text
equivalents, but can be made possible when using math content encoded in
MathML.

In the past, it is sad to say that math accessibility was not considered a
viable concern among many educators. It was not unusual to hear people express
the opinion that math was not a primary subject needing much focus, that
providing access to math content was too difficult, or that most students with
disabilities would simply find math too complex anyway and therefore not worth
the trouble. At Design Science, we reject these notions as regressive and
insulting to people with disabilities. Such old attitudes are now changing, and
greater levels of effective access to mathematical information has been made
available thanks to continuing improvements in math accessibility. Although there are many technical
issues involved in making math accessible, Design Science wants you to know
that we have found solutions for many of these issues, and are actively involved
in research projects with an aim to design even better math accessibility
technologies in the near future.
For users with special needs, having access to math
information in something other than just ink on paper is essential. In
educational settings many students with
print disabilities
must rely upon alternative format materials in place of standard print in order
to access textbooks, tests, classroom handouts or other types of instructional
content. Having math displayed on a computer screen begins to remedy some
accessibility issues by providing an environment where the content can be
enlarged for people with low vision, or by allowing someone with no use of their
hands to virtually "turn pages." But the common current practice of using graphical images to represent mathematical
equations in computer applications, such as using GIF or JPG image files to
display math in Web pages, does nothing to make those equations accessible to many people
with disabilities who depend upon assistive technologies like synthetic speech
or refreshable braille displays.
By using MathML to create universally designed accessible math equations, the resulting content
can be translated into any other imaginable output format needed, which ensures
that alternative formats that meet a student's access needs will be available
for use with their assistive technology. Math with accessible equations can be
rendered with synthetic speech, can be utilized with synchronized highlighting,
and can be also converted into braille math code for blind students.
Synchronized highlighting of math equations on a computer screen with synthetic
speech helps those with low vision, and can be a significant aid to students
with learning disabilities.
Accessible equations, unlike images, will format and
display correctly on PDAs and on highresolution output devices not yet
invented. They can use larger fonts and match a user's preferred color schemes.
Accessible equations will form the basis of universally designed math
instructional content, as well as fully accessible math assessments for use by
all students. By having accessible math content available in instructional
software, ebooks, and assessments, all students will have equal access to the
same content and the same learning supports, regardless of whether or not they
have a disability. This eliminates the need to have a totally separate process
to create an alternative format at a later date, and virtually guarantees that
students with disabilities will be able to access the same content at the same
time as students without disabilities.
Most of the math equations one currently finds in digital environments like
the Web are simply static bitmaps (digital drawings) of equation images in GIF, PNG,
or JPEG formats. These images can be seen with the human eye, but they are
devoid of nonvisual information that can be utilized by assistive technologies.
Such image formats are, by themselves, inherently inaccessible. They do not
provide for alternative output modalities, such as braille or synthetic speech
and cannot be easily altered for people with low vision (for example, font
enlargement or color and contrast changes). Furthermore, such image formats are
plagued by other usability and aesthetic problems such as ease of alignment,
sizing, and color conformity with the text, require the author to spend much
more editing time to make visually appealing web content, and require authors to
keep a large inventory of static equation images which are not easily editable, requiring the author to
redraw images when even small changes are made. Finally, images take up
relatively large amounts of bandwidth, which is a hindrance for lowspeed
Internet connections.
The typical method of providing accessibility to common images in digital
environments is by including a written description of the graphic referred to as
a "text equivalent," generally either an
"alt" tag
or a "long
description." For most images this will be sufficient to
comply to minimum accessibility standards, such as those required under
Federal Section 508
Electronic and Information Technology Accessibility Standards or the W3C's
Web Content Accessibility
Guidelines. However, providing alt tags to graphical images of math
equations can only provide a very limited form of accessibility for the simplest
types of equations.
Alt tags are limited to a narrative description of math
equations, and must be laboriously hand coded by someone who can fully
understand the context of the expression and unambiguously describe it with
complete consistency. Even if this could be guaranteed, there would still be no
way to intelligently navigate though a math equation, and still doesn't fix some
of the previously mentioned issues like support for brailled math output. So
although the use of properly authored alt tags may supply minimum access to math
content, it is still a far cry from the maxim that individuals with disabilities
should "have access to and use of information and data that is comparable to
that provided to the public who are not individuals with disabilities" as
mandated by the provisions of the
1998
Amendment to Section 508 of the Rehabilitation Act.
As we just discussed, math images (with or without a text equivalent) cannot provide a
level of access that is comparable to, or as effective as, the level of access
that individuals without disabilities are being provided. Instead, the preferred
(and vastly more effective) technique is to use a
standardized markup language that can be accessed by the assistive technologies
that people with disabilities use. Using such a technique means that the author
has to encode information only once because there is no need to go back through
a second time and add an alternative (alt tag) description. The same coding
supplies, at the same time, the needs of both those who use and those who do not
use assistive technologies, and hence is a much more effective authoring method.
MathML (Mathematical Markup Language)
has been adopted by the W3C as the standard way of expressing math on the Web,
and provides the basis for math equations that can be both rendered visually on
the screen and also available through alternative access means. MathML contains
sufficient information and structure to provide support for both visual display
and alternative access means such as synthetic speech and braille. Equations
which are encoded in MathML will increase in size as users change font size to
increase readability, unlike images. When using synthetic speech, MathML will
allow the user to set different verbosity levels and can automatically adjust
for the user's native language. For braille users, using MathML will allow for
the choice of various braille math formats, depending upon braille translation
software support.
Turning math expressions into audio form can be a very effective form of
alternative access for people who have visual or learning disabilities. Images
of equations do not by themselves supply information to support any form of
audio rendering, although text equivalents can be audibly rendered by synthetic
speech applications as mentioned previously. Producers of alternative format
materials can also provide previously recorded audio files (either from human
readers or synthetic speech used at the producer end) that can supply an audio
rendering of math equations in digital environments even without the presence of
a screen or text reader on the end user system, as is commonly done in currently
available Digital Talking Books. This approach does provide access for users
with visual or learning disabilities, but would be of no benefit for deafblind
users. Just as in the case of text equivalents, this type of audio rendering can
only supply a very limited level of accessibility and only for the most simple
equations.
However, much more coherent and consistent audio rendering of math
expressions is available when using MathML. Synthetic speech engines used by
students who are blind, such as JAWS, WindowEyes, HAL, Supernova, MAGic, and Serotek
System Access, and text readers
used by students who have learning disabilities, like TextHelp's Read & Write Gold
and BrowseAloud, can
already seamlessly interface the reading of MathML math expressions by using
MathPlayer. Further development of math speech technologies will allow user customization of speech
generation rules and control of prosodic cues such as the pitch and rhythm of
the math speech, which will help to increase the
comprehension rate of users for both the structure the content of
the expression.
Since, in comparison to the number of people who are blind, there are many
more users who can see but who have some form of visual impairment (commonly
referred to as having "low vision") the need to enlarge mathematical equations
on a computer screen is much more common. Such users may also need to change
the color of the font as well as the background of the display. Math images
(graphical formats) do not enlarge well, and cannot be enlarged by simply
changing browser settings. There is also no simple user defined method available
to change image colors. When math equations are encoded in MathML, however,
visual definition does not degrade with size increase, and users have control
over the size, color, and contrast of math font display just as they do for
literary text. MathML also provides for consistent linebreaking when math
equations are enlarged, which
is important for all users but particularly important for people
with low vision.
Most of the text reader applications currently on the market make use of
synchronized highlighting
of literary text as the words are being spoken. This technique is also available
with Digital Talking Books when they are used with visual display environments.
Synchronous highlighting is beneficial for students with learning disabilities
or attention deficit disorders, as well as for students with low vision.
Although significant research has been conducted demonstrating the value of
synchronous highlighting toward increasing reading comprehension of literary
materials, the fact that synchronous highlighting of math has only recently
become possible has limited the availability of research supporting increased
comprehension of math expressions through synchronous highlighting to this
point. However, the implication that synchronous highlighting of math
expressions as they are spoken increases comprehension seems very likely.
Math equations which have been encoded in MathML can permit a range of
highlighting reinforcement options. Equations can be broken down into various
subcomponent sections as they are being spoken depending upon the flexibility
provided within the reading application. The degree of highlighting granularity
desired will likely depend upon the individual student's instructional need or
user preference.
The ability to provide math access through refreshable braille
displays and hard copy braille output is important for both blind and deafblind
users. Most good braille readers
find audioonly access to
mathematics considerably inferior to braille or combined braille and audio
access. Math images cannot be accessed by braille, but braille access to math
encoded in MathML can be provided. However, there are a number of competing math
braille codes in use around the world, which complicates the ability to support
braille output for MathML. A relatively new type of two dimensional math braille
called
DotsPlus is simple to produce with MathML content. Support for other
commonly used math braille, like Nemeth code, is dependent upon MathML support
by makers of braille translation software.
The ability to better comprehend longer or more complex mathematical
equations in audio form is aided by user navigation within the equation to hear
different expression elements separately. This is not feasible with prerecorded
audio files or text equivalents, but can be made possible when using math
content encoded in MathML.
Allowing navigation of math expressions using keyboard commands will allow
the user to explore the structure of an equation at the user's own pace.
Although it may be difficult to comprehend especially long equations through
audio access only, the ability to audibly walk through an unambiguous vocalization of the
expression and subdivide lengthy equations at natural "chunking" spots greatly
enhances intelligibility of accessible math expressions.
Further Information and Resources
