[Accessibility-handlers] Speech Use Cases -- Draft 1

Janina Sajka janina at a11y.org
Mon Aug 6 10:06:56 PDT 2007

Herewith my first rough cut of use cases for the speech user

Computer users who are blind or severly visually impaired often use
assistive technology (AT) built around synthetic text to speech (TTS).
These AT applications are commonly called "screen readers." Screen
reader users listen to a synthetic voice rendering of on screen content
because they are physically unable to see this content on a computer
display monitor.

Because synthetic voice rendering is intrinsicallyh temporal, whereas on
screen displays are (or can easily be made) static, various strategies
are provided by screen readers to allow users to tightly control the
alternative TTS rendering. Screen reader users often find it useful, for instance,  to skim through
content until a particular portion is located and then examine that
portion in a more controlled manner, perhaps word by word or even
character by rendered character. It is almost never useful to waith for
a synthetic voice rendering that begins at the upper left of the screen
and proceeds left to right, row by row, until it reaches the bottom
because such a procedure is temporally inefficient, requiring the user to strain to hear just the portion
desired in the midst of unsought content. Thus, screen readers provide
mechanisms that allow the user to focus anywhere in the content and
examine only that content which is of interest.

Screen readers have proven highly effective at providing their users
access to content which is intrinsically textual and linear in nature.
It is not hard to provide mechanisms to focus synthetic voice rendering
paragraph by paragraph, sentence by sentence, word by word, or character
by character.

Access to on screen widgets have also proven effective by rendering that
static content in list form, where the user can pick from a menu of
options using up and down arrow plus the enter key to indicate a
selection, in liue of picking an icon on screen using a mouse.

Access to content arrayed in a table can also succeed by allowing the AT
to simulate the process a sighted user employs to consider tables. In
other words, mechanisms are provided to hear the contents of a cell and
also the row and column labels for that cell (which define the cell's

Similar "smart" content rendering and navigation strategies are required
by screen reader users in more complex, nonlinear content such as
mathematical (chemical, biological, etc) expressions, music, and
graphical renderings. Because such content is generally the province of
knowledge domain experts and students, and not the domain of most
computer users, screen readers do not invest the significant resources
necessary to serve only a small portion of their customer base with
specialized routines for such content. Furthermore, the general
rendering and navigation strategies provided for linear (textual), menu,
and tabular content are woefully insufficient to allow users to examine
specific portions of such domain specific expressions effectively.  On
the other hand domain specific markup often does provide sufficient
specificity so that the focus and rendering needs of the screen reader
can be welkl supported.

In order to gain effective access to such domain specific content screen
reader users require technology that can:

*	Synthetically voice the expression in a logical order

*	Allow the user to focus on particular, logical portions of
*	expressions possibly at several layers of granularity

*	Appropriately voice specialized symbols and symbolic expressions


Janina Sajka,	Phone:	+1.202.595.7777;	sip:janina at a11y.org
Partner, Capital Accessibility LLC	http://CapitalAccessibility.Com

Marketing the Owasys 22C talking screenless cell phone in the U.S. and Canada
Learn more at http://ScreenlessPhone.Com

Chair, Open Accessibility	janina at a11y.org	
Linux Foundation		http://a11y.org

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