<s>
A	O
voice	B-Application
font	I-Application
is	O
a	O
computer-generated	B-Application
voice	I-Application
that	O
can	O
be	O
controlled	O
by	O
specifying	O
parameters	O
such	O
as	O
speed	O
and	O
pitch	O
and	O
made	O
to	O
pronounce	O
text	O
input	O
.	O
</s>
<s>
In	O
spite	O
of	O
current	O
shortcomings	O
in	O
the	O
underlying	O
technology	O
for	O
voice	B-Application
fonts	I-Application
,	O
screen	O
readers	O
and	O
other	O
devices	O
used	O
to	O
enhance	O
accessibility	O
of	O
text	O
to	O
persons	O
with	O
disabilities	O
,	O
can	O
benefit	O
from	O
having	O
more	O
than	O
one	O
default	O
voice	B-Application
font	I-Application
.	O
</s>
<s>
This	O
happens	O
in	O
the	O
same	O
way	O
that	O
users	O
of	O
a	O
traditional	O
computer	O
word	B-General_Concept
processor	I-General_Concept
benefit	O
from	O
having	O
more	O
than	O
one	O
text	O
font	O
.	O
</s>
<s>
The	O
synthesized	O
voice	O
created	O
by	O
using	O
a	O
voice	B-Application
font	I-Application
tends	O
to	O
have	O
a	O
slightly	O
unnatural	O
tone	O
.	O
</s>
<s>
Voice	B-Application
font	I-Application
software	O
on	O
the	O
Macintosh	B-Device
system	O
tries	O
to	O
get	O
around	O
this	O
by	O
providing	O
tags	O
to	O
change	O
some	O
components	O
of	O
the	O
voice	O
,	O
such	O
as	O
pitch	O
.	O
</s>
<s>
Even	O
though	O
speech	B-Application
synthesis	I-Application
has	O
existed	O
since	O
around	O
1930	O
,	O
according	O
to	O
that	O
source	O
,	O
and	O
the	O
Speech	B-Application
synthesis	I-Application
article	O
,	O
it	O
is	O
difficult	O
to	O
fool	O
experienced	O
listeners	O
into	O
believing	O
that	O
the	O
voice	O
is	O
indeed	O
human	O
.	O
</s>
<s>
This	O
may	O
be	O
similar	O
to	O
the	O
difficulty	O
in	O
achieving	O
true	O
Artificial	B-Application
Intelligence	I-Application
that	O
can	O
actually	O
pass	O
a	O
Turing	O
Test	O
by	O
presenting	O
spectators	O
with	O
something	O
indistinguishable	O
from	O
what	O
it	O
is	O
trying	O
to	O
simulate	O
.	O
</s>
<s>
Like	O
its	O
text	O
counterpart	O
,	O
each	O
voice	B-Application
font	I-Application
can	O
supply	O
a	O
different	O
experience	O
and	O
provide	O
a	O
selection	O
for	O
different	O
purposes	O
.	O
</s>
<s>
The	O
simplest	O
one	O
is	O
to	O
select	O
a	O
voice	B-Application
font	I-Application
from	O
a	O
group	O
in	O
order	O
to	O
get	O
the	O
clearest	O
one	O
,	O
or	O
to	O
choose	O
the	O
one	O
with	O
a	O
speed	O
that	O
is	O
appropriate	O
for	O
different	O
settings	O
.	O
</s>
<s>
Another	O
use	O
for	O
voice	B-Application
fonts	I-Application
is	O
in	O
electronic	O
music	O
.	O
</s>
<s>
A	O
commonly	O
available	O
set	O
of	O
synthetic	B-Application
voices	I-Application
from	O
Macintosh	B-Device
computers	O
can	O
be	O
used	O
to	O
enhance	O
the	O
mood	O
of	O
certain	O
music	O
pieces	O
that	O
need	O
a	O
voice	O
but	O
where	O
the	O
composer	O
feels	O
that	O
providing	O
a	O
human	O
voice	O
is	O
not	O
in	O
their	O
interests	O
.	O
</s>
<s>
Here	O
,	O
male	O
voices	O
can	O
be	O
combined	O
in	O
a	O
choir	O
to	O
provide	O
the	O
tenor	O
and	O
bass	O
for	O
a	O
particular	O
piece	O
,	O
and	O
female	O
voices	O
can	O
be	O
added	O
to	O
fill	O
in	O
other	O
parts	O
of	O
the	O
ensemble	O
—	O
resulting	O
in	O
a	O
choir	O
that	O
consists	O
of	O
speech	B-Application
synthesis	I-Application
rather	O
than	O
human	O
singers	O
,	O
or	O
to	O
utilize	O
a	O
female	O
voice	O
when	O
none	O
are	O
available	O
.	O
</s>
<s>
Certain	O
Macintosh	B-Device
clients	O
of	O
instant	B-Application
messaging	I-Application
services	O
such	O
as	O
AOL	B-Protocol
Instant	I-Protocol
Messenger	I-Protocol
had	O
the	O
option	O
of	O
reading	O
incoming	O
messages	O
using	O
the	O
system	O
's	O
voice	B-Application
fonts	I-Application
.	O
</s>
