Off-Topic: Computing for the Blind

Polytropon freebsd at
Mon Mar 26 22:13:04 UTC 2012

On Mon, 26 Mar 2012 14:21:08 -0500, Martin McCormick wrote:
> 	The easiest and most economical interface for computer
> users who are blind is spoken speach.

That's correct. However, unlike a Braille readout which
gives tactile information (through the reader's hands),
synthetic voice cannot easily accomodate to the reader's
habits and reading speed. "Scanning text" is not possible
as the generated voiced text is played in "linear time",
which means you cannot easily skip forward and backward,
re-read a certain passage, and you basically do not come
down to the "letter level", you only have a "word level".
While this has benefits in "unconcentrated reading" (e. g.
reading an article or literature", it can be problematic
with scientific or technical text where a (healthy) reader
would let his eyes "jump" within the text stream.

> 	One can learn to type and touch-typing was tought in
> schools for the blind for scores of years before computers ever
> even came on the scene.

I also learned typewriting (mandatory!) in school, and
believe it or not, it comes handy every time I have to
deal with a computer. :-)

> We pounded on typewriters and our
> poor suffering typing teachers were the feedback mechanisms that
> told us how we were doing. So, a person who is blind needs to
> know how to type.

A good keyboard can help here. Keep in mind that a keyboard,
being a means of input, provides tactile feedback as output.
So without any visual confirmation you can detect when you
made a typing error, activating a "motor program" to correct
it on the fly.

At this point, I typically recommend using an IBM Model M
keyboard. But the Sun USB Type 7 is also good, as it provides
programmable keys for volume control, application interaction
and Braille readout control. (I use those keys primarily for
dealing with the window manager - no need to use the eyes!)

> 	None of these screen readers are perfect, but most
> computer users who are blind end up being reasonably happy with
> one of them.

Especially in combination with web browsers, they are prone
to fail. Where there's no text (as content) in a web page,
there's nothing to read to the user. The use of the HTML
tags alt= and longdesc= is a long forgotten art, and when
"Flash" enters the scene to replace few lines of HTML (as
for links or simple text), there's no easy way to determine
_what_ currently is on the screen.

> 	There are also Braille displays which some people use
> but they are extremely costly.

Sadly, that is correct. In my opinion this is because they
are a niche market. When purchasing one, you have to pay
attention to if it can capture "normal text screen" content.
How is it attached to the computer? Does it require proprietary
drivers? How long can it be used before an OS revision breaks
the drivers?

Those Braille readouts can be placed infront of the keyboard,
the primary means of input. Reading and writing isn't far
away from each other (finger travelling distance).

Classic Braille readouts didn't seem to require any driver.
I've seen such devices in the past. A slider on the side
simply defined the row of text which was then displayed on
the readout - one out of 25. I think it was plugged into
the VGA chain (PC -> readout -> screen), but I'm not that
familiar with this technology; I've seen it on a DOS PC.
However, as FreeBSD's default screen mode is 80x25 text
mode, it should be possible to use such a device. Maybe
it's possible to get a used one for cheap...

> 	I mentioned the speech recognition systems. Many of
> those actually present problems for those who are blind because
> you need to train them on your speech and the feedback is
> graphical so a good old keyboard is still the best input device.

Speech recognition requires training. Both the user and the
system have to learn from each other. But you have a learning
curve everywhere, be it typing, talking, or reading from a
Braille output.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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