[MUSIC PLAYING]
PRESENTER: I'd like
now to introduce to you
Professor Stephen Hawking.
In your handouts, you'll find
a very elaborate introduction.
And you will find very
interesting elements in it.
As a distinguished
educator, researcher,
and public communicator,
Stephen Hawking
has had a transforming effect
in his area, and indeed,
in all of science.
We are deeply appreciative of
his commitment to be with us
and to share his views of
the importance of applying
technology to disabled persons.
Professor Stephen Hawking.
[APPLAUSE]
HAWKING: Can you hear me?
AUDIENCE: Yes.
HAWKING: Technology
has transformed
the outlook for the disabled.
People like me can now
move around independently,
and they can communicate.
The fact that you
are listening to me
now shows what
technology can do even
if it does give me a
Scandinavian or American
accent.
[LAUGHTER]
The main problem
of communicating
for people like
me who can't speak
is what is called
the baud rate, that
is the rate at which
information can be conveyed.
Normal speed is between
120 and 180 words a minute.
By contrast, a reasonable typist
can do 40 to 60 words a minute.
Thus, if one were to equip
normal people with keyboards,
they could communicate
at between half
and a quarter of
the speech rate.
However, many people
who can't speak
also have other
disabilities, like me,
and can't use a keyboard.
Instead, they have to use
one or more switches operated
by a head or hand movement.
This is where the information
flow problem really
confronts one.
One might be able to operate
a switch two or three times
a second.
This would mean that one
could send information
at a rate of two or
three bits a second.
One bit of information is the
answer to a yes/no question.
By contrast, if you
take an average work
to be about five
characters, and you
assume that any character can
follow any other character,
normal speech has an information
flow rate of between 50 and 75
bits a second.
However, the real information
flow in human speech
is much less than this.
In the case of
political speeches,
it has practically zero.
[LAUGHTER]
This is because spelling out
a sentence letter by letter
is inefficient.
Most sequences of letters
don't make recognizable words,
let alone meaningful sentences.
So there's a lot of redundancy
in specifying every letter.
It is much more
efficient to pick
words, or even whole phrases,
from a list of likely ones.
In the occasional cases that the
words or phrases don't appear
on the list, one can always
resort to spelling them
out letter by letter.
To translate the
presses of a switch
into letters, words, or
sentences requires computers.
The development of
microprocessors in the last 15
years has meant that virtually
unlimited computing power is
available at a reasonable cost.
What one needs is
sufficient software
to translate the input from
the switch into sentences.
I can manage about
15 words a minute
with the equalizer
program that I use.
That is not too bad, since an
information flow rate of three
bits a second corresponds
to 25 to 30 words a minute.
But obviously, there's
scope for improvement.
Having decoded the signals
from some input device,
such as a switch, one
then has to broadcast it
in a form people can understand.
This could be visually, with
text or diagrams on a screen.
But if you want to
communicate like others,
which is what people in
my position would like,
you need to speak.
Computerized speech
synthesizers have improved
a great deal in recent years.
And this is important.
Not only does one
want to be understood,
but also one doesn't
want to sound
like Mickey Mouse or a Dalek.
This voice of mine may
be a bit tinny and Irish,
but it is almost human.
There are other ways
in which technology
can assist the disabled.
For instance, I have infrared
and radio environment control
with which I can open
doors, turn on lights,
and operate the television.
I also have a mobile phone that
I can use to call for help.
If one is unfortunate
enough to be disabled,
this is the age
in which to be so.
I probably wouldn't
have survived,
and I certainly
wouldn't have been
able to write a
best-selling book,
I had been born any earlier.
The disabled have a lot
to thank technology for.
That is all I have to
say for the moment.
Thank you for listening.
[APPLAUSE]
